Merge branch 'bpf-sk-lookup'

Joe Stringer says:

====================
This series proposes a new helper for the BPF API which allows BPF programs to
perform lookups for sockets in a network namespace. This would allow programs
to determine early on in processing whether the stack is expecting to receive
the packet, and perform some action (eg drop, forward somewhere) based on this
information.

The series is structured roughly into:
* Misc refactor
* Add the socket pointer type
* Add reference tracking to ensure that socket references are freed
* Extend the BPF API to add sk_lookup_xxx() / sk_release() functions
* Add tests/documentation

The helper proposed in this series includes a parameter for a tuple which must
be filled in by the caller to determine the socket to look up. The simplest
case would be filling with the contents of the packet, ie mapping the packet's
5-tuple into the parameter. In common cases, it may alternatively be useful to
reverse the direction of the tuple and perform a lookup, to find the socket
that initiates this connection; and if the BPF program ever performs a form of
IP address translation, it may further be useful to be able to look up
arbitrary tuples that are not based upon the packet, but instead based on state
held in BPF maps or hardcoded in the BPF program.

Currently, access into the socket's fields are limited to those which are
otherwise already accessible, and are restricted to read-only access.

Changes since v3:
* New patch: "bpf: Reuse canonical string formatter for ctx errs"
* Add PTR_TO_SOCKET to is_ctx_reg().
* Add a few new checks to prevent mixing of socket/non-socket pointers.
* Swap order of checks in sock_filter_is_valid_access().
* Prefix register spill macros with "bpf_".
* Add acks from previous round
* Rebase

Changes since v2:
* New patch: "selftests/bpf: Generalize dummy program types".
  This enables adding verifier tests for socket lookup with tail calls.
* Define the semantics of the new helpers more clearly in uAPI header.
* Fix release of caller_net when netns is not specified.
* Use skb->sk to find caller net when skb->dev is unavailable.
* Fix build with !CONFIG_NET.
* Replace ptr_id defensive coding when releasing reference state with an
  internal error (-EFAULT).
* Remove flags argument to sk_release().
* Add several new assembly tests suggested by Daniel.
* Add a few new C tests.
* Fix typo in verifier error message.

Changes since v1:
* Limit netns_id field to 32 bits
* Reuse reg_type_mismatch() in more places
* Reduce the number of passes at convert_ctx_access()
* Replace ptr_id defensive coding when releasing reference state with an
  internal error (-EFAULT)
* Rework 'struct bpf_sock_tuple' to allow passing a packet pointer
* Allow direct packet access from helper
* Fix compile error with CONFIG_IPV6 enabled
* Improve commit messages

Changes since RFC:
* Split up sk_lookup() into sk_lookup_tcp(), sk_lookup_udp().
* Only take references on the socket when necessary.
  * Make sk_release() only free the socket reference in this case.
* Fix some runtime reference leaks:
  * Disallow BPF_LD_[ABS|IND] instructions while holding a reference.
  * Disallow bpf_tail_call() while holding a reference.
* Prevent the same instruction being used for reference and other
  pointer type.
* Simplify locating copies of a reference during helper calls by caching
  the pointer id from the caller.
* Fix kbuild compilation warnings with particular configs.
* Improve code comments describing the new verifier pieces.
* Tested by Nitin
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Documentation/networking/filter.txt

@@ -1125,6 +1125,14 @@ pointer type.  The types of pointers describe their base, as follows:
     PTR_TO_STACK        Frame pointer.
     PTR_TO_PACKET       skb->data.
     PTR_TO_PACKET_END   skb->data + headlen; arithmetic forbidden.
+    PTR_TO_SOCKET       Pointer to struct bpf_sock_ops, implicitly refcounted.
+    PTR_TO_SOCKET_OR_NULL
+                        Either a pointer to a socket, or NULL; socket lookup
+                        returns this type, which becomes a PTR_TO_SOCKET when
+                        checked != NULL. PTR_TO_SOCKET is reference-counted,
+                        so programs must release the reference through the
+                        socket release function before the end of the program.
+                        Arithmetic on these pointers is forbidden.
 However, a pointer may be offset from this base (as a result of pointer
 arithmetic), and this is tracked in two parts: the 'fixed offset' and 'variable
 offset'.  The former is used when an exactly-known value (e.g. an immediate
@@ -1171,6 +1179,13 @@ over the Ethernet header, then reads IHL and addes (IHL * 4), the resulting
 pointer will have a variable offset known to be 4n+2 for some n, so adding the 2
 bytes (NET_IP_ALIGN) gives a 4-byte alignment and so word-sized accesses through
 that pointer are safe.
+The 'id' field is also used on PTR_TO_SOCKET and PTR_TO_SOCKET_OR_NULL, common
+to all copies of the pointer returned from a socket lookup. This has similar
+behaviour to the handling for PTR_TO_MAP_VALUE_OR_NULL->PTR_TO_MAP_VALUE, but
+it also handles reference tracking for the pointer. PTR_TO_SOCKET implicitly
+represents a reference to the corresponding 'struct sock'. To ensure that the
+reference is not leaked, it is imperative to NULL-check the reference and in
+the non-NULL case, and pass the valid reference to the socket release function.
 
 Direct packet access
 --------------------
@@ -1444,6 +1459,55 @@ Error:
   8: (7a) *(u64 *)(r0 +0) = 1
   R0 invalid mem access 'imm'
 
+Program that performs a socket lookup then sets the pointer to NULL without
+checking it:
+value:
+  BPF_MOV64_IMM(BPF_REG_2, 0),
+  BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_2, -8),
+  BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+  BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+  BPF_MOV64_IMM(BPF_REG_3, 4),
+  BPF_MOV64_IMM(BPF_REG_4, 0),
+  BPF_MOV64_IMM(BPF_REG_5, 0),
+  BPF_EMIT_CALL(BPF_FUNC_sk_lookup_tcp),
+  BPF_MOV64_IMM(BPF_REG_0, 0),
+  BPF_EXIT_INSN(),
+Error:
+  0: (b7) r2 = 0
+  1: (63) *(u32 *)(r10 -8) = r2
+  2: (bf) r2 = r10
+  3: (07) r2 += -8
+  4: (b7) r3 = 4
+  5: (b7) r4 = 0
+  6: (b7) r5 = 0
+  7: (85) call bpf_sk_lookup_tcp#65
+  8: (b7) r0 = 0
+  9: (95) exit
+  Unreleased reference id=1, alloc_insn=7
+
+Program that performs a socket lookup but does not NULL-check the returned
+value:
+  BPF_MOV64_IMM(BPF_REG_2, 0),
+  BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_2, -8),
+  BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+  BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+  BPF_MOV64_IMM(BPF_REG_3, 4),
+  BPF_MOV64_IMM(BPF_REG_4, 0),
+  BPF_MOV64_IMM(BPF_REG_5, 0),
+  BPF_EMIT_CALL(BPF_FUNC_sk_lookup_tcp),
+  BPF_EXIT_INSN(),
+Error:
+  0: (b7) r2 = 0
+  1: (63) *(u32 *)(r10 -8) = r2
+  2: (bf) r2 = r10
+  3: (07) r2 += -8
+  4: (b7) r3 = 4
+  5: (b7) r4 = 0
+  6: (b7) r5 = 0
+  7: (85) call bpf_sk_lookup_tcp#65
+  8: (95) exit
+  Unreleased reference id=1, alloc_insn=7
+
 Testing
 -------
 

include/linux/bpf.h

@@ -154,6 +154,7 @@ enum bpf_arg_type {
 
 	ARG_PTR_TO_CTX,		/* pointer to context */
 	ARG_ANYTHING,		/* any (initialized) argument is ok */
+	ARG_PTR_TO_SOCKET,	/* pointer to bpf_sock */
 };
 
 /* type of values returned from helper functions */
@@ -162,6 +163,7 @@ enum bpf_return_type {
 	RET_VOID,			/* function doesn't return anything */
 	RET_PTR_TO_MAP_VALUE,		/* returns a pointer to map elem value */
 	RET_PTR_TO_MAP_VALUE_OR_NULL,	/* returns a pointer to map elem value or NULL */
+	RET_PTR_TO_SOCKET_OR_NULL,	/* returns a pointer to a socket or NULL */
 };
 
 /* eBPF function prototype used by verifier to allow BPF_CALLs from eBPF programs
@@ -213,6 +215,8 @@ enum bpf_reg_type {
 	PTR_TO_PACKET,		 /* reg points to skb->data */
 	PTR_TO_PACKET_END,	 /* skb->data + headlen */
 	PTR_TO_FLOW_KEYS,	 /* reg points to bpf_flow_keys */
+	PTR_TO_SOCKET,		 /* reg points to struct bpf_sock */
+	PTR_TO_SOCKET_OR_NULL,	 /* reg points to struct bpf_sock or NULL */
 };
 
 /* The information passed from prog-specific *_is_valid_access
@@ -343,6 +347,11 @@ const struct bpf_func_proto *bpf_get_trace_printk_proto(void);
 
 typedef unsigned long (*bpf_ctx_copy_t)(void *dst, const void *src,
 					unsigned long off, unsigned long len);
+typedef u32 (*bpf_convert_ctx_access_t)(enum bpf_access_type type,
+					const struct bpf_insn *src,
+					struct bpf_insn *dst,
+					struct bpf_prog *prog,
+					u32 *target_size);
 
 u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size,
 		     void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy);
@@ -836,4 +845,29 @@ extern const struct bpf_func_proto bpf_get_local_storage_proto;
 void bpf_user_rnd_init_once(void);
 u64 bpf_user_rnd_u32(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
 
+#if defined(CONFIG_NET)
+bool bpf_sock_is_valid_access(int off, int size, enum bpf_access_type type,
+			      struct bpf_insn_access_aux *info);
+u32 bpf_sock_convert_ctx_access(enum bpf_access_type type,
+				const struct bpf_insn *si,
+				struct bpf_insn *insn_buf,
+				struct bpf_prog *prog,
+				u32 *target_size);
+#else
+static inline bool bpf_sock_is_valid_access(int off, int size,
+					    enum bpf_access_type type,
+					    struct bpf_insn_access_aux *info)
+{
+	return false;
+}
+static inline u32 bpf_sock_convert_ctx_access(enum bpf_access_type type,
+					      const struct bpf_insn *si,
+					      struct bpf_insn *insn_buf,
+					      struct bpf_prog *prog,
+					      u32 *target_size)
+{
+	return 0;
+}
+#endif
+
 #endif /* _LINUX_BPF_H */

include/linux/bpf_verifier.h

@@ -58,6 +58,8 @@ struct bpf_reg_state {
 	 * offset, so they can share range knowledge.
 	 * For PTR_TO_MAP_VALUE_OR_NULL this is used to share which map value we
 	 * came from, when one is tested for != NULL.
+	 * For PTR_TO_SOCKET this is used to share which pointers retain the
+	 * same reference to the socket, to determine proper reference freeing.
 	 */
 	u32 id;
 	/* For scalar types (SCALAR_VALUE), this represents our knowledge of
@@ -102,6 +104,17 @@ struct bpf_stack_state {
 	u8 slot_type[BPF_REG_SIZE];
 };
 
+struct bpf_reference_state {
+	/* Track each reference created with a unique id, even if the same
+	 * instruction creates the reference multiple times (eg, via CALL).
+	 */
+	int id;
+	/* Instruction where the allocation of this reference occurred. This
+	 * is used purely to inform the user of a reference leak.
+	 */
+	int insn_idx;
+};
+
 /* state of the program:
  * type of all registers and stack info
  */
@@ -119,7 +132,9 @@ struct bpf_func_state {
 	 */
 	u32 subprogno;
 
-	/* should be second to last. See copy_func_state() */
+	/* The following fields should be last. See copy_func_state() */
+	int acquired_refs;
+	struct bpf_reference_state *refs;
 	int allocated_stack;
 	struct bpf_stack_state *stack;
 };
@@ -131,6 +146,17 @@ struct bpf_verifier_state {
 	u32 curframe;
 };
 
+#define bpf_get_spilled_reg(slot, frame)				\
+	(((slot < frame->allocated_stack / BPF_REG_SIZE) &&		\
+	  (frame->stack[slot].slot_type[0] == STACK_SPILL))		\
+	 ? &frame->stack[slot].spilled_ptr : NULL)
+
+/* Iterate over 'frame', setting 'reg' to either NULL or a spilled register. */
+#define bpf_for_each_spilled_reg(iter, frame, reg)			\
+	for (iter = 0, reg = bpf_get_spilled_reg(iter, frame);		\
+	     iter < frame->allocated_stack / BPF_REG_SIZE;		\
+	     iter++, reg = bpf_get_spilled_reg(iter, frame))
+
 /* linked list of verifier states used to prune search */
 struct bpf_verifier_state_list {
 	struct bpf_verifier_state state;
@@ -204,11 +230,16 @@ __printf(2, 0) void bpf_verifier_vlog(struct bpf_verifier_log *log,
 __printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env,
 					   const char *fmt, ...);
 
-static inline struct bpf_reg_state *cur_regs(struct bpf_verifier_env *env)
+static inline struct bpf_func_state *cur_func(struct bpf_verifier_env *env)
 {
 	struct bpf_verifier_state *cur = env->cur_state;
 
-	return cur->frame[cur->curframe]->regs;
+	return cur->frame[cur->curframe];
+}
+
+static inline struct bpf_reg_state *cur_regs(struct bpf_verifier_env *env)
+{
+	return cur_func(env)->regs;
 }
 
 int bpf_prog_offload_verifier_prep(struct bpf_verifier_env *env);

include/uapi/linux/bpf.h

@@ -2144,6 +2144,77 @@ union bpf_attr {
  *		request in the skb.
  *	Return
  *		0 on success, or a negative error in case of failure.
+ *
+ * struct bpf_sock *bpf_sk_lookup_tcp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u32 netns, u64 flags)
+ *	Description
+ *		Look for TCP socket matching *tuple*, optionally in a child
+ *		network namespace *netns*. The return value must be checked,
+ *		and if non-NULL, released via **bpf_sk_release**\ ().
+ *
+ *		The *ctx* should point to the context of the program, such as
+ *		the skb or socket (depending on the hook in use). This is used
+ *		to determine the base network namespace for the lookup.
+ *
+ *		*tuple_size* must be one of:
+ *
+ *		**sizeof**\ (*tuple*\ **->ipv4**)
+ *			Look for an IPv4 socket.
+ *		**sizeof**\ (*tuple*\ **->ipv6**)
+ *			Look for an IPv6 socket.
+ *
+ *		If the *netns* is zero, then the socket lookup table in the
+ *		netns associated with the *ctx* will be used. For the TC hooks,
+ *		this in the netns of the device in the skb. For socket hooks,
+ *		this in the netns of the socket. If *netns* is non-zero, then
+ *		it specifies the ID of the netns relative to the netns
+ *		associated with the *ctx*.
+ *
+ *		All values for *flags* are reserved for future usage, and must
+ *		be left at zero.
+ *
+ *		This helper is available only if the kernel was compiled with
+ *		**CONFIG_NET** configuration option.
+ *	Return
+ *		Pointer to *struct bpf_sock*, or NULL in case of failure.
+ *
+ * struct bpf_sock *bpf_sk_lookup_udp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u32 netns, u64 flags)
+ *	Description
+ *		Look for UDP socket matching *tuple*, optionally in a child
+ *		network namespace *netns*. The return value must be checked,
+ *		and if non-NULL, released via **bpf_sk_release**\ ().
+ *
+ *		The *ctx* should point to the context of the program, such as
+ *		the skb or socket (depending on the hook in use). This is used
+ *		to determine the base network namespace for the lookup.
+ *
+ *		*tuple_size* must be one of:
+ *
+ *		**sizeof**\ (*tuple*\ **->ipv4**)
+ *			Look for an IPv4 socket.
+ *		**sizeof**\ (*tuple*\ **->ipv6**)
+ *			Look for an IPv6 socket.
+ *
+ *		If the *netns* is zero, then the socket lookup table in the
+ *		netns associated with the *ctx* will be used. For the TC hooks,
+ *		this in the netns of the device in the skb. For socket hooks,
+ *		this in the netns of the socket. If *netns* is non-zero, then
+ *		it specifies the ID of the netns relative to the netns
+ *		associated with the *ctx*.
+ *
+ *		All values for *flags* are reserved for future usage, and must
+ *		be left at zero.
+ *
+ *		This helper is available only if the kernel was compiled with
+ *		**CONFIG_NET** configuration option.
+ *	Return
+ *		Pointer to *struct bpf_sock*, or NULL in case of failure.
+ *
+ * int bpf_sk_release(struct bpf_sock *sk)
+ *	Description
+ *		Release the reference held by *sock*. *sock* must be a non-NULL
+ *		pointer that was returned from bpf_sk_lookup_xxx\ ().
+ *	Return
+ *		0 on success, or a negative error in case of failure.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -2229,7 +2300,10 @@ union bpf_attr {
 	FN(get_current_cgroup_id),	\
 	FN(get_local_storage),		\
 	FN(sk_select_reuseport),	\
-	FN(skb_ancestor_cgroup_id),
+	FN(skb_ancestor_cgroup_id),	\
+	FN(sk_lookup_tcp),		\
+	FN(sk_lookup_udp),		\
+	FN(sk_release),
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
  * function eBPF program intends to call
@@ -2399,6 +2473,23 @@ struct bpf_sock {
 				 */
 };
 
+struct bpf_sock_tuple {
+	union {
+		struct {
+			__be32 saddr;
+			__be32 daddr;
+			__be16 sport;
+			__be16 dport;
+		} ipv4;
+		struct {
+			__be32 saddr[4];
+			__be32 daddr[4];
+			__be16 sport;
+			__be16 dport;
+		} ipv6;
+	};
+};
+
 #define XDP_PACKET_HEADROOM 256
 
 /* User return codes for XDP prog type.

kernel/bpf/verifier.c

@@ -1,5 +1,6 @@
 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
  * Copyright (c) 2016 Facebook
+ * Copyright (c) 2018 Covalent IO, Inc. http://covalent.io
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of version 2 of the GNU General Public
@@ -80,8 +81,8 @@ static const struct bpf_verifier_ops * const bpf_verifier_ops[] = {
  * (like pointer plus pointer becomes SCALAR_VALUE type)
  *
  * When verifier sees load or store instructions the type of base register
- * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, PTR_TO_STACK. These are three pointer
- * types recognized by check_mem_access() function.
+ * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, PTR_TO_STACK, PTR_TO_SOCKET. These are
+ * four pointer types recognized by check_mem_access() function.
  *
  * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value'
  * and the range of [ptr, ptr + map's value_size) is accessible.
@@ -140,6 +141,24 @@ static const struct bpf_verifier_ops * const bpf_verifier_ops[] = {
  *
  * After the call R0 is set to return type of the function and registers R1-R5
  * are set to NOT_INIT to indicate that they are no longer readable.
+ *
+ * The following reference types represent a potential reference to a kernel
+ * resource which, after first being allocated, must be checked and freed by
+ * the BPF program:
+ * - PTR_TO_SOCKET_OR_NULL, PTR_TO_SOCKET
+ *
+ * When the verifier sees a helper call return a reference type, it allocates a
+ * pointer id for the reference and stores it in the current function state.
+ * Similar to the way that PTR_TO_MAP_VALUE_OR_NULL is converted into
+ * PTR_TO_MAP_VALUE, PTR_TO_SOCKET_OR_NULL becomes PTR_TO_SOCKET when the type
+ * passes through a NULL-check conditional. For the branch wherein the state is
+ * changed to CONST_IMM, the verifier releases the reference.
+ *
+ * For each helper function that allocates a reference, such as
+ * bpf_sk_lookup_tcp(), there is a corresponding release function, such as
+ * bpf_sk_release(). When a reference type passes into the release function,
+ * the verifier also releases the reference. If any unchecked or unreleased
+ * reference remains at the end of the program, the verifier rejects it.
  */
 
 /* verifier_state + insn_idx are pushed to stack when branch is encountered */
@@ -189,6 +208,7 @@ struct bpf_call_arg_meta {
 	int access_size;
 	s64 msize_smax_value;
 	u64 msize_umax_value;
+	int ptr_id;
 };
 
 static DEFINE_MUTEX(bpf_verifier_lock);
@@ -249,6 +269,46 @@ static bool type_is_pkt_pointer(enum bpf_reg_type type)
 	       type == PTR_TO_PACKET_META;
 }
 
+static bool reg_type_may_be_null(enum bpf_reg_type type)
+{
+	return type == PTR_TO_MAP_VALUE_OR_NULL ||
+	       type == PTR_TO_SOCKET_OR_NULL;
+}
+
+static bool type_is_refcounted(enum bpf_reg_type type)
+{
+	return type == PTR_TO_SOCKET;
+}
+
+static bool type_is_refcounted_or_null(enum bpf_reg_type type)
+{
+	return type == PTR_TO_SOCKET || type == PTR_TO_SOCKET_OR_NULL;
+}
+
+static bool reg_is_refcounted(const struct bpf_reg_state *reg)
+{
+	return type_is_refcounted(reg->type);
+}
+
+static bool reg_is_refcounted_or_null(const struct bpf_reg_state *reg)
+{
+	return type_is_refcounted_or_null(reg->type);
+}
+
+static bool arg_type_is_refcounted(enum bpf_arg_type type)
+{
+	return type == ARG_PTR_TO_SOCKET;
+}
+
+/* Determine whether the function releases some resources allocated by another
+ * function call. The first reference type argument will be assumed to be
+ * released by release_reference().
+ */
+static bool is_release_function(enum bpf_func_id func_id)
+{
+	return func_id == BPF_FUNC_sk_release;
+}
+
 /* string representation of 'enum bpf_reg_type' */
 static const char * const reg_type_str[] = {
 	[NOT_INIT]		= "?",
@@ -262,6 +322,8 @@ static const char * const reg_type_str[] = {
 	[PTR_TO_PACKET_META]	= "pkt_meta",
 	[PTR_TO_PACKET_END]	= "pkt_end",
 	[PTR_TO_FLOW_KEYS]	= "flow_keys",
+	[PTR_TO_SOCKET]		= "sock",
+	[PTR_TO_SOCKET_OR_NULL] = "sock_or_null",
 };
 
 static char slot_type_char[] = {
@@ -378,62 +440,158 @@ static void print_verifier_state(struct bpf_verifier_env *env,
 		else
 			verbose(env, "=%s", types_buf);
 	}
+	if (state->acquired_refs && state->refs[0].id) {
+		verbose(env, " refs=%d", state->refs[0].id);
+		for (i = 1; i < state->acquired_refs; i++)
+			if (state->refs[i].id)
+				verbose(env, ",%d", state->refs[i].id);
+	}
 	verbose(env, "\n");
 }
 
-static int copy_stack_state(struct bpf_func_state *dst,
-			    const struct bpf_func_state *src)
-{
-	if (!src->stack)
-		return 0;
-	if (WARN_ON_ONCE(dst->allocated_stack < src->allocated_stack)) {
-		/* internal bug, make state invalid to reject the program */
-		memset(dst, 0, sizeof(*dst));
-		return -EFAULT;
-	}
-	memcpy(dst->stack, src->stack,
-	       sizeof(*src->stack) * (src->allocated_stack / BPF_REG_SIZE));
-	return 0;
-}
+#define COPY_STATE_FN(NAME, COUNT, FIELD, SIZE)				\
+static int copy_##NAME##_state(struct bpf_func_state *dst,		\
+			       const struct bpf_func_state *src)	\
+{									\
+	if (!src->FIELD)						\
+		return 0;						\
+	if (WARN_ON_ONCE(dst->COUNT < src->COUNT)) {			\
+		/* internal bug, make state invalid to reject the program */ \
+		memset(dst, 0, sizeof(*dst));				\
+		return -EFAULT;						\
+	}								\
+	memcpy(dst->FIELD, src->FIELD,					\
+	       sizeof(*src->FIELD) * (src->COUNT / SIZE));		\
+	return 0;							\
+}
+/* copy_reference_state() */
+COPY_STATE_FN(reference, acquired_refs, refs, 1)
+/* copy_stack_state() */
+COPY_STATE_FN(stack, allocated_stack, stack, BPF_REG_SIZE)
+#undef COPY_STATE_FN
+
+#define REALLOC_STATE_FN(NAME, COUNT, FIELD, SIZE)			\
+static int realloc_##NAME##_state(struct bpf_func_state *state, int size, \
+				  bool copy_old)			\
+{									\
+	u32 old_size = state->COUNT;					\
+	struct bpf_##NAME##_state *new_##FIELD;				\
+	int slot = size / SIZE;						\
+									\
+	if (size <= old_size || !size) {				\
+		if (copy_old)						\
+			return 0;					\
+		state->COUNT = slot * SIZE;				\
+		if (!size && old_size) {				\
+			kfree(state->FIELD);				\
+			state->FIELD = NULL;				\
+		}							\
+		return 0;						\
+	}								\
+	new_##FIELD = kmalloc_array(slot, sizeof(struct bpf_##NAME##_state), \
+				    GFP_KERNEL);			\
+	if (!new_##FIELD)						\
+		return -ENOMEM;						\
+	if (copy_old) {							\
+		if (state->FIELD)					\
+			memcpy(new_##FIELD, state->FIELD,		\
+			       sizeof(*new_##FIELD) * (old_size / SIZE)); \
+		memset(new_##FIELD + old_size / SIZE, 0,		\
+		       sizeof(*new_##FIELD) * (size - old_size) / SIZE); \
+	}								\
+	state->COUNT = slot * SIZE;					\
+	kfree(state->FIELD);						\
+	state->FIELD = new_##FIELD;					\
+	return 0;							\
+}
+/* realloc_reference_state() */
+REALLOC_STATE_FN(reference, acquired_refs, refs, 1)
+/* realloc_stack_state() */
+REALLOC_STATE_FN(stack, allocated_stack, stack, BPF_REG_SIZE)
+#undef REALLOC_STATE_FN
 
 /* do_check() starts with zero-sized stack in struct bpf_verifier_state to
  * make it consume minimal amount of memory. check_stack_write() access from
  * the program calls into realloc_func_state() to grow the stack size.
- * Note there is a non-zero parent pointer inside each reg of bpf_verifier_state
- * which this function copies over. It points to corresponding reg in previous
- * bpf_verifier_state which is never reallocated
+ * Note there is a non-zero 'parent' pointer inside bpf_verifier_state
+ * which realloc_stack_state() copies over. It points to previous
+ * bpf_verifier_state which is never reallocated.
  */
-static int realloc_func_state(struct bpf_func_state *state, int size,
-			      bool copy_old)
+static int realloc_func_state(struct bpf_func_state *state, int stack_size,
+			      int refs_size, bool copy_old)
 {
-	u32 old_size = state->allocated_stack;
-	struct bpf_stack_state *new_stack;
-	int slot = size / BPF_REG_SIZE;
+	int err = realloc_reference_state(state, refs_size, copy_old);
+	if (err)
+		return err;
+	return realloc_stack_state(state, stack_size, copy_old);
+}
+
+/* Acquire a pointer id from the env and update the state->refs to include
+ * this new pointer reference.
+ * On success, returns a valid pointer id to associate with the register
+ * On failure, returns a negative errno.
+ */
+static int acquire_reference_state(struct bpf_verifier_env *env, int insn_idx)
+{
+	struct bpf_func_state *state = cur_func(env);
+	int new_ofs = state->acquired_refs;
+	int id, err;
 
-	if (size <= old_size || !size) {
-		if (copy_old)
+	err = realloc_reference_state(state, state->acquired_refs + 1, true);
+	if (err)
+		return err;
+	id = ++env->id_gen;
+	state->refs[new_ofs].id = id;
+	state->refs[new_ofs].insn_idx = insn_idx;
+
+	return id;
+}
+
+/* release function corresponding to acquire_reference_state(). Idempotent. */
+static int __release_reference_state(struct bpf_func_state *state, int ptr_id)
+{
+	int i, last_idx;
+
+	if (!ptr_id)
+		return -EFAULT;
+
+	last_idx = state->acquired_refs - 1;
+	for (i = 0; i < state->acquired_refs; i++) {
+		if (state->refs[i].id == ptr_id) {
+			if (last_idx && i != last_idx)
+				memcpy(&state->refs[i], &state->refs[last_idx],
+				       sizeof(*state->refs));
+			memset(&state->refs[last_idx], 0, sizeof(*state->refs));
+			state->acquired_refs--;
 			return 0;
-		state->allocated_stack = slot * BPF_REG_SIZE;
-		if (!size && old_size) {
-			kfree(state->stack);
-			state->stack = NULL;
 		}
-		return 0;
 	}
-	new_stack = kmalloc_array(slot, sizeof(struct bpf_stack_state),
-				  GFP_KERNEL);
-	if (!new_stack)
-		return -ENOMEM;
-	if (copy_old) {
-		if (state->stack)
-			memcpy(new_stack, state->stack,
-			       sizeof(*new_stack) * (old_size / BPF_REG_SIZE));
-		memset(new_stack + old_size / BPF_REG_SIZE, 0,
-		       sizeof(*new_stack) * (size - old_size) / BPF_REG_SIZE);
-	}
-	state->allocated_stack = slot * BPF_REG_SIZE;
-	kfree(state->stack);
-	state->stack = new_stack;
+	return -EFAULT;
+}
+
+/* variation on the above for cases where we expect that there must be an
+ * outstanding reference for the specified ptr_id.
+ */
+static int release_reference_state(struct bpf_verifier_env *env, int ptr_id)
+{
+	struct bpf_func_state *state = cur_func(env);
+	int err;
+
+	err = __release_reference_state(state, ptr_id);
+	if (WARN_ON_ONCE(err != 0))
+		verbose(env, "verifier internal error: can't release reference\n");
+	return err;
+}
+
+static int transfer_reference_state(struct bpf_func_state *dst,
+				    struct bpf_func_state *src)
+{
+	int err = realloc_reference_state(dst, src->acquired_refs, false);
+	if (err)
+		return err;
+	err = copy_reference_state(dst, src);
+	if (err)
+		return err;
 	return 0;
 }
 
@@ -441,6 +599,7 @@ static void free_func_state(struct bpf_func_state *state)
 {
 	if (!state)
 		return;
+	kfree(state->refs);
 	kfree(state->stack);
 	kfree(state);
 }
@@ -466,10 +625,14 @@ static int copy_func_state(struct bpf_func_state *dst,
 {
 	int err;
 
-	err = realloc_func_state(dst, src->allocated_stack, false);
+	err = realloc_func_state(dst, src->allocated_stack, src->acquired_refs,
+				 false);
+	if (err)
+		return err;
+	memcpy(dst, src, offsetof(struct bpf_func_state, acquired_refs));
+	err = copy_reference_state(dst, src);
 	if (err)
 		return err;
-	memcpy(dst, src, offsetof(struct bpf_func_state, allocated_stack));
 	return copy_stack_state(dst, src);
 }
 
@@ -968,6 +1131,8 @@ static bool is_spillable_regtype(enum bpf_reg_type type)
 	case PTR_TO_PACKET_END:
 	case PTR_TO_FLOW_KEYS:
 	case CONST_PTR_TO_MAP:
+	case PTR_TO_SOCKET:
+	case PTR_TO_SOCKET_OR_NULL:
 		return true;
 	default:
 		return false;
@@ -992,7 +1157,7 @@ static int check_stack_write(struct bpf_verifier_env *env,
 	enum bpf_reg_type type;
 
 	err = realloc_func_state(state, round_up(slot + 1, BPF_REG_SIZE),
-				 true);
+				 state->acquired_refs, true);
 	if (err)
 		return err;
 	/* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
@@ -1336,6 +1501,28 @@ static int check_flow_keys_access(struct bpf_verifier_env *env, int off,
 	return 0;
 }
 
+static int check_sock_access(struct bpf_verifier_env *env, u32 regno, int off,
+			     int size, enum bpf_access_type t)
+{
+	struct bpf_reg_state *regs = cur_regs(env);
+	struct bpf_reg_state *reg = &regs[regno];
+	struct bpf_insn_access_aux info;
+
+	if (reg->smin_value < 0) {
+		verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
+			regno);
+		return -EACCES;
+	}
+
+	if (!bpf_sock_is_valid_access(off, size, t, &info)) {
+		verbose(env, "invalid bpf_sock access off=%d size=%d\n",
+			off, size);
+		return -EACCES;
+	}
+
+	return 0;
+}
+
 static bool __is_pointer_value(bool allow_ptr_leaks,
 			       const struct bpf_reg_state *reg)
 {
@@ -1354,7 +1541,8 @@ static bool is_ctx_reg(struct bpf_verifier_env *env, int regno)
 {
 	const struct bpf_reg_state *reg = cur_regs(env) + regno;
 
-	return reg->type == PTR_TO_CTX;
+	return reg->type == PTR_TO_CTX ||
+	       reg->type == PTR_TO_SOCKET;
 }
 
 static bool is_pkt_reg(struct bpf_verifier_env *env, int regno)
@@ -1454,6 +1642,9 @@ static int check_ptr_alignment(struct bpf_verifier_env *env,
 		 */
 		strict = true;
 		break;
+	case PTR_TO_SOCKET:
+		pointer_desc = "sock ";
+		break;
 	default:
 		break;
 	}
@@ -1721,6 +1912,14 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
 		err = check_flow_keys_access(env, off, size);
 		if (!err && t == BPF_READ && value_regno >= 0)
 			mark_reg_unknown(env, regs, value_regno);
+	} else if (reg->type == PTR_TO_SOCKET) {
+		if (t == BPF_WRITE) {
+			verbose(env, "cannot write into socket\n");
+			return -EACCES;
+		}
+		err = check_sock_access(env, regno, off, size, t);
+		if (!err && value_regno >= 0)
+			mark_reg_unknown(env, regs, value_regno);
 	} else {
 		verbose(env, "R%d invalid mem access '%s'\n", regno,
 			reg_type_str[reg->type]);
@@ -1763,8 +1962,7 @@ static int check_xadd(struct bpf_verifier_env *env, int insn_idx, struct bpf_ins
 	if (is_ctx_reg(env, insn->dst_reg) ||
 	    is_pkt_reg(env, insn->dst_reg)) {
 		verbose(env, "BPF_XADD stores into R%d %s is not allowed\n",
-			insn->dst_reg, is_ctx_reg(env, insn->dst_reg) ?
-			"context" : "packet");
+			insn->dst_reg, reg_type_str[insn->dst_reg]);
 		return -EACCES;
 	}
 
@@ -1944,6 +2142,16 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 regno,
 		err = check_ctx_reg(env, reg, regno);
 		if (err < 0)
 			return err;
+	} else if (arg_type == ARG_PTR_TO_SOCKET) {
+		expected_type = PTR_TO_SOCKET;
+		if (type != expected_type)
+			goto err_type;
+		if (meta->ptr_id || !reg->id) {
+			verbose(env, "verifier internal error: mismatched references meta=%d, reg=%d\n",
+				meta->ptr_id, reg->id);
+			return -EFAULT;
+		}
+		meta->ptr_id = reg->id;
 	} else if (arg_type_is_mem_ptr(arg_type)) {
 		expected_type = PTR_TO_STACK;
 		/* One exception here. In case function allows for NULL to be
@@ -2233,10 +2441,32 @@ static bool check_arg_pair_ok(const struct bpf_func_proto *fn)
 	return true;
 }
 
+static bool check_refcount_ok(const struct bpf_func_proto *fn)
+{
+	int count = 0;
+
+	if (arg_type_is_refcounted(fn->arg1_type))
+		count++;
+	if (arg_type_is_refcounted(fn->arg2_type))
+		count++;
+	if (arg_type_is_refcounted(fn->arg3_type))
+		count++;
+	if (arg_type_is_refcounted(fn->arg4_type))
+		count++;
+	if (arg_type_is_refcounted(fn->arg5_type))
+		count++;
+
+	/* We only support one arg being unreferenced at the moment,
+	 * which is sufficient for the helper functions we have right now.
+	 */
+	return count <= 1;
+}
+
 static int check_func_proto(const struct bpf_func_proto *fn)
 {
 	return check_raw_mode_ok(fn) &&
-	       check_arg_pair_ok(fn) ? 0 : -EINVAL;
+	       check_arg_pair_ok(fn) &&
+	       check_refcount_ok(fn) ? 0 : -EINVAL;
 }
 
 /* Packet data might have moved, any old PTR_TO_PACKET[_META,_END]
@@ -2252,10 +2482,9 @@ static void __clear_all_pkt_pointers(struct bpf_verifier_env *env,
 		if (reg_is_pkt_pointer_any(&regs[i]))
 			mark_reg_unknown(env, regs, i);
 
-	for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
-		if (state->stack[i].slot_type[0] != STACK_SPILL)
+	bpf_for_each_spilled_reg(i, state, reg) {
+		if (!reg)
 			continue;
-		reg = &state->stack[i].spilled_ptr;
 		if (reg_is_pkt_pointer_any(reg))
 			__mark_reg_unknown(reg);
 	}
@@ -2270,12 +2499,45 @@ static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
 		__clear_all_pkt_pointers(env, vstate->frame[i]);
 }
 
+static void release_reg_references(struct bpf_verifier_env *env,
+				   struct bpf_func_state *state, int id)
+{
+	struct bpf_reg_state *regs = state->regs, *reg;
+	int i;
+
+	for (i = 0; i < MAX_BPF_REG; i++)
+		if (regs[i].id == id)
+			mark_reg_unknown(env, regs, i);
+
+	bpf_for_each_spilled_reg(i, state, reg) {
+		if (!reg)
+			continue;
+		if (reg_is_refcounted(reg) && reg->id == id)
+			__mark_reg_unknown(reg);
+	}
+}
+
+/* The pointer with the specified id has released its reference to kernel
+ * resources. Identify all copies of the same pointer and clear the reference.
+ */
+static int release_reference(struct bpf_verifier_env *env,
+			     struct bpf_call_arg_meta *meta)
+{
+	struct bpf_verifier_state *vstate = env->cur_state;
+	int i;
+
+	for (i = 0; i <= vstate->curframe; i++)
+		release_reg_references(env, vstate->frame[i], meta->ptr_id);
+
+	return release_reference_state(env, meta->ptr_id);
+}
+
 static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
 			   int *insn_idx)
 {
 	struct bpf_verifier_state *state = env->cur_state;
 	struct bpf_func_state *caller, *callee;
-	int i, subprog, target_insn;
+	int i, err, subprog, target_insn;
 
 	if (state->curframe + 1 >= MAX_CALL_FRAMES) {
 		verbose(env, "the call stack of %d frames is too deep\n",
@@ -2313,6 +2575,11 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
 			state->curframe + 1 /* frameno within this callchain */,
 			subprog /* subprog number within this prog */);
 
+	/* Transfer references to the callee */
+	err = transfer_reference_state(callee, caller);
+	if (err)
+		return err;
+
 	/* copy r1 - r5 args that callee can access.  The copy includes parent
 	 * pointers, which connects us up to the liveness chain
 	 */
@@ -2345,6 +2612,7 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx)
 	struct bpf_verifier_state *state = env->cur_state;
 	struct bpf_func_state *caller, *callee;
 	struct bpf_reg_state *r0;
+	int err;
 
 	callee = state->frame[state->curframe];
 	r0 = &callee->regs[BPF_REG_0];
@@ -2364,6 +2632,11 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx)
 	/* return to the caller whatever r0 had in the callee */
 	caller->regs[BPF_REG_0] = *r0;
 
+	/* Transfer references to the caller */
+	err = transfer_reference_state(caller, callee);
+	if (err)
+		return err;
+
 	*insn_idx = callee->callsite + 1;
 	if (env->log.level) {
 		verbose(env, "returning from callee:\n");
@@ -2420,6 +2693,18 @@ record_func_map(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta,
 	return 0;
 }
 
+static int check_reference_leak(struct bpf_verifier_env *env)
+{
+	struct bpf_func_state *state = cur_func(env);
+	int i;
+
+	for (i = 0; i < state->acquired_refs; i++) {
+		verbose(env, "Unreleased reference id=%d alloc_insn=%d\n",
+			state->refs[i].id, state->refs[i].insn_idx);
+	}
+	return state->acquired_refs ? -EINVAL : 0;
+}
+
 static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn_idx)
 {
 	const struct bpf_func_proto *fn = NULL;
@@ -2498,6 +2783,18 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn
 			return err;
 	}
 
+	if (func_id == BPF_FUNC_tail_call) {
+		err = check_reference_leak(env);
+		if (err) {
+			verbose(env, "tail_call would lead to reference leak\n");
+			return err;
+		}
+	} else if (is_release_function(func_id)) {
+		err = release_reference(env, &meta);
+		if (err)
+			return err;
+	}
+
 	regs = cur_regs(env);
 
 	/* check that flags argument in get_local_storage(map, flags) is 0,
@@ -2540,6 +2837,13 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn
 		}
 		regs[BPF_REG_0].map_ptr = meta.map_ptr;
 		regs[BPF_REG_0].id = ++env->id_gen;
+	} else if (fn->ret_type == RET_PTR_TO_SOCKET_OR_NULL) {
+		int id = acquire_reference_state(env, insn_idx);
+		if (id < 0)
+			return id;
+		mark_reg_known_zero(env, regs, BPF_REG_0);
+		regs[BPF_REG_0].type = PTR_TO_SOCKET_OR_NULL;
+		regs[BPF_REG_0].id = id;
 	} else {
 		verbose(env, "unknown return type %d of func %s#%d\n",
 			fn->ret_type, func_id_name(func_id), func_id);
@@ -2670,20 +2974,20 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
 		return -EACCES;
 	}
 
-	if (ptr_reg->type == PTR_TO_MAP_VALUE_OR_NULL) {
-		verbose(env, "R%d pointer arithmetic on PTR_TO_MAP_VALUE_OR_NULL prohibited, null-check it first\n",
-			dst);
-		return -EACCES;
-	}
-	if (ptr_reg->type == CONST_PTR_TO_MAP) {
-		verbose(env, "R%d pointer arithmetic on CONST_PTR_TO_MAP prohibited\n",
-			dst);
+	switch (ptr_reg->type) {
+	case PTR_TO_MAP_VALUE_OR_NULL:
+		verbose(env, "R%d pointer arithmetic on %s prohibited, null-check it first\n",
+			dst, reg_type_str[ptr_reg->type]);
 		return -EACCES;
-	}
-	if (ptr_reg->type == PTR_TO_PACKET_END) {
-		verbose(env, "R%d pointer arithmetic on PTR_TO_PACKET_END prohibited\n",
-			dst);
+	case CONST_PTR_TO_MAP:
+	case PTR_TO_PACKET_END:
+	case PTR_TO_SOCKET:
+	case PTR_TO_SOCKET_OR_NULL:
+		verbose(env, "R%d pointer arithmetic on %s prohibited\n",
+			dst, reg_type_str[ptr_reg->type]);
 		return -EACCES;
+	default:
+		break;
 	}
 
 	/* In case of 'scalar += pointer', dst_reg inherits pointer type and id.
@@ -3395,10 +3699,9 @@ static void find_good_pkt_pointers(struct bpf_verifier_state *vstate,
 
 	for (j = 0; j <= vstate->curframe; j++) {
 		state = vstate->frame[j];
-		for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
-			if (state->stack[i].slot_type[0] != STACK_SPILL)
+		bpf_for_each_spilled_reg(i, state, reg) {
+			if (!reg)
 				continue;
-			reg = &state->stack[i].spilled_ptr;
 			if (reg->type == type && reg->id == dst_reg->id)
 				reg->range = max(reg->range, new_range);
 		}
@@ -3604,12 +3907,11 @@ static void reg_combine_min_max(struct bpf_reg_state *true_src,
 	}
 }
 
-static void mark_map_reg(struct bpf_reg_state *regs, u32 regno, u32 id,
-			 bool is_null)
+static void mark_ptr_or_null_reg(struct bpf_func_state *state,
+				 struct bpf_reg_state *reg, u32 id,
+				 bool is_null)
 {
-	struct bpf_reg_state *reg = &regs[regno];
-
-	if (reg->type == PTR_TO_MAP_VALUE_OR_NULL && reg->id == id) {
+	if (reg_type_may_be_null(reg->type) && reg->id == id) {
 		/* Old offset (both fixed and variable parts) should
 		 * have been known-zero, because we don't allow pointer
 		 * arithmetic on pointers that might be NULL.
@@ -3622,40 +3924,49 @@ static void mark_map_reg(struct bpf_reg_state *regs, u32 regno, u32 id,
 		}
 		if (is_null) {
 			reg->type = SCALAR_VALUE;
-		} else if (reg->map_ptr->inner_map_meta) {
-			reg->type = CONST_PTR_TO_MAP;
-			reg->map_ptr = reg->map_ptr->inner_map_meta;
-		} else {
-			reg->type = PTR_TO_MAP_VALUE;
+		} else if (reg->type == PTR_TO_MAP_VALUE_OR_NULL) {
+			if (reg->map_ptr->inner_map_meta) {
+				reg->type = CONST_PTR_TO_MAP;
+				reg->map_ptr = reg->map_ptr->inner_map_meta;
+			} else {
+				reg->type = PTR_TO_MAP_VALUE;
+			}
+		} else if (reg->type == PTR_TO_SOCKET_OR_NULL) {
+			reg->type = PTR_TO_SOCKET;
+		}
+		if (is_null || !reg_is_refcounted(reg)) {
+			/* We don't need id from this point onwards anymore,
+			 * thus we should better reset it, so that state
+			 * pruning has chances to take effect.
+			 */
+			reg->id = 0;
 		}
-		/* We don't need id from this point onwards anymore, thus we
-		 * should better reset it, so that state pruning has chances
-		 * to take effect.
-		 */
-		reg->id = 0;
 	}
 }
 
 /* The logic is similar to find_good_pkt_pointers(), both could eventually
  * be folded together at some point.
  */
-static void mark_map_regs(struct bpf_verifier_state *vstate, u32 regno,
-			  bool is_null)
+static void mark_ptr_or_null_regs(struct bpf_verifier_state *vstate, u32 regno,
+				  bool is_null)
 {
 	struct bpf_func_state *state = vstate->frame[vstate->curframe];
-	struct bpf_reg_state *regs = state->regs;
+	struct bpf_reg_state *reg, *regs = state->regs;
 	u32 id = regs[regno].id;
 	int i, j;
 
+	if (reg_is_refcounted_or_null(&regs[regno]) && is_null)
+		__release_reference_state(state, id);
+
 	for (i = 0; i < MAX_BPF_REG; i++)
-		mark_map_reg(regs, i, id, is_null);
+		mark_ptr_or_null_reg(state, &regs[i], id, is_null);
 
 	for (j = 0; j <= vstate->curframe; j++) {
 		state = vstate->frame[j];
-		for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
-			if (state->stack[i].slot_type[0] != STACK_SPILL)
+		bpf_for_each_spilled_reg(i, state, reg) {
+			if (!reg)
 				continue;
-			mark_map_reg(&state->stack[i].spilled_ptr, 0, id, is_null);
+			mark_ptr_or_null_reg(state, reg, id, is_null);
 		}
 	}
 }
@@ -3857,12 +4168,14 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env,
 	/* detect if R == 0 where R is returned from bpf_map_lookup_elem() */
 	if (BPF_SRC(insn->code) == BPF_K &&
 	    insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) &&
-	    dst_reg->type == PTR_TO_MAP_VALUE_OR_NULL) {
-		/* Mark all identical map registers in each branch as either
+	    reg_type_may_be_null(dst_reg->type)) {
+		/* Mark all identical registers in each branch as either
 		 * safe or unknown depending R == 0 or R != 0 conditional.
 		 */
-		mark_map_regs(this_branch, insn->dst_reg, opcode == BPF_JNE);
-		mark_map_regs(other_branch, insn->dst_reg, opcode == BPF_JEQ);
+		mark_ptr_or_null_regs(this_branch, insn->dst_reg,
+				      opcode == BPF_JNE);
+		mark_ptr_or_null_regs(other_branch, insn->dst_reg,
+				      opcode == BPF_JEQ);
 	} else if (!try_match_pkt_pointers(insn, dst_reg, &regs[insn->src_reg],
 					   this_branch, other_branch) &&
 		   is_pointer_value(env, insn->dst_reg)) {
@@ -3985,6 +4298,16 @@ static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
 	if (err)
 		return err;
 
+	/* Disallow usage of BPF_LD_[ABS|IND] with reference tracking, as
+	 * gen_ld_abs() may terminate the program at runtime, leading to
+	 * reference leak.
+	 */
+	err = check_reference_leak(env);
+	if (err) {
+		verbose(env, "BPF_LD_[ABS|IND] cannot be mixed with socket references\n");
+		return err;
+	}
+
 	if (regs[BPF_REG_6].type != PTR_TO_CTX) {
 		verbose(env,
 			"at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
@@ -4400,6 +4723,8 @@ static bool regsafe(struct bpf_reg_state *rold, struct bpf_reg_state *rcur,
 	case CONST_PTR_TO_MAP:
 	case PTR_TO_PACKET_END:
 	case PTR_TO_FLOW_KEYS:
+	case PTR_TO_SOCKET:
+	case PTR_TO_SOCKET_OR_NULL:
 		/* Only valid matches are exact, which memcmp() above
 		 * would have accepted
 		 */
@@ -4475,6 +4800,14 @@ static bool stacksafe(struct bpf_func_state *old,
 	return true;
 }
 
+static bool refsafe(struct bpf_func_state *old, struct bpf_func_state *cur)
+{
+	if (old->acquired_refs != cur->acquired_refs)
+		return false;
+	return !memcmp(old->refs, cur->refs,
+		       sizeof(*old->refs) * old->acquired_refs);
+}
+
 /* compare two verifier states
  *
  * all states stored in state_list are known to be valid, since
@@ -4520,6 +4853,9 @@ static bool func_states_equal(struct bpf_func_state *old,
 
 	if (!stacksafe(old, cur, idmap))
 		goto out_free;
+
+	if (!refsafe(old, cur))
+		goto out_free;
 	ret = true;
 out_free:
 	kfree(idmap);
@@ -4677,6 +5013,37 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
 	return 0;
 }
 
+/* Return true if it's OK to have the same insn return a different type. */
+static bool reg_type_mismatch_ok(enum bpf_reg_type type)
+{
+	switch (type) {
+	case PTR_TO_CTX:
+	case PTR_TO_SOCKET:
+	case PTR_TO_SOCKET_OR_NULL:
+		return false;
+	default:
+		return true;
+	}
+}
+
+/* If an instruction was previously used with particular pointer types, then we
+ * need to be careful to avoid cases such as the below, where it may be ok
+ * for one branch accessing the pointer, but not ok for the other branch:
+ *
+ * R1 = sock_ptr
+ * goto X;
+ * ...
+ * R1 = some_other_valid_ptr;
+ * goto X;
+ * ...
+ * R2 = *(u32 *)(R1 + 0);
+ */
+static bool reg_type_mismatch(enum bpf_reg_type src, enum bpf_reg_type prev)
+{
+	return src != prev && (!reg_type_mismatch_ok(src) ||
+			       !reg_type_mismatch_ok(prev));
+}
+
 static int do_check(struct bpf_verifier_env *env)
 {
 	struct bpf_verifier_state *state;
@@ -4770,6 +5137,7 @@ static int do_check(struct bpf_verifier_env *env)
 
 		regs = cur_regs(env);
 		env->insn_aux_data[insn_idx].seen = true;
+
 		if (class == BPF_ALU || class == BPF_ALU64) {
 			err = check_alu_op(env, insn);
 			if (err)
@@ -4809,9 +5177,7 @@ static int do_check(struct bpf_verifier_env *env)
 				 */
 				*prev_src_type = src_reg_type;
 
-			} else if (src_reg_type != *prev_src_type &&
-				   (src_reg_type == PTR_TO_CTX ||
-				    *prev_src_type == PTR_TO_CTX)) {
+			} else if (reg_type_mismatch(src_reg_type, *prev_src_type)) {
 				/* ABuser program is trying to use the same insn
 				 * dst_reg = *(u32*) (src_reg + off)
 				 * with different pointer types:
@@ -4856,9 +5222,7 @@ static int do_check(struct bpf_verifier_env *env)
 
 			if (*prev_dst_type == NOT_INIT) {
 				*prev_dst_type = dst_reg_type;
-			} else if (dst_reg_type != *prev_dst_type &&
-				   (dst_reg_type == PTR_TO_CTX ||
-				    *prev_dst_type == PTR_TO_CTX)) {
+			} else if (reg_type_mismatch(dst_reg_type, *prev_dst_type)) {
 				verbose(env, "same insn cannot be used with different pointers\n");
 				return -EINVAL;
 			}
@@ -4875,8 +5239,8 @@ static int do_check(struct bpf_verifier_env *env)
 				return err;
 
 			if (is_ctx_reg(env, insn->dst_reg)) {
-				verbose(env, "BPF_ST stores into R%d context is not allowed\n",
-					insn->dst_reg);
+				verbose(env, "BPF_ST stores into R%d %s is not allowed\n",
+					insn->dst_reg, reg_type_str[insn->dst_reg]);
 				return -EACCES;
 			}
 
@@ -4938,6 +5302,10 @@ static int do_check(struct bpf_verifier_env *env)
 					continue;
 				}
 
+				err = check_reference_leak(env);
+				if (err)
+					return err;
+
 				/* eBPF calling convetion is such that R0 is used
 				 * to return the value from eBPF program.
 				 * Make sure that it's readable at this time
@@ -5284,8 +5652,10 @@ static void sanitize_dead_code(struct bpf_verifier_env *env)
 	}
 }
 
-/* convert load instructions that access fields of 'struct __sk_buff'
- * into sequence of instructions that access fields of 'struct sk_buff'
+/* convert load instructions that access fields of a context type into a
+ * sequence of instructions that access fields of the underlying structure:
+ *     struct __sk_buff    -> struct sk_buff
+ *     struct bpf_sock_ops -> struct sock
  */
 static int convert_ctx_accesses(struct bpf_verifier_env *env)
 {
@@ -5314,12 +5684,14 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
 		}
 	}
 
-	if (!ops->convert_ctx_access || bpf_prog_is_dev_bound(env->prog->aux))
+	if (bpf_prog_is_dev_bound(env->prog->aux))
 		return 0;
 
 	insn = env->prog->insnsi + delta;
 
 	for (i = 0; i < insn_cnt; i++, insn++) {
+		bpf_convert_ctx_access_t convert_ctx_access;
+
 		if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) ||
 		    insn->code == (BPF_LDX | BPF_MEM | BPF_H) ||
 		    insn->code == (BPF_LDX | BPF_MEM | BPF_W) ||
@@ -5361,8 +5733,18 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
 			continue;
 		}
 
-		if (env->insn_aux_data[i + delta].ptr_type != PTR_TO_CTX)
+		switch (env->insn_aux_data[i + delta].ptr_type) {
+		case PTR_TO_CTX:
+			if (!ops->convert_ctx_access)
+				continue;
+			convert_ctx_access = ops->convert_ctx_access;
+			break;
+		case PTR_TO_SOCKET:
+			convert_ctx_access = bpf_sock_convert_ctx_access;
+			break;
+		default:
 			continue;
+		}
 
 		ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size;
 		size = BPF_LDST_BYTES(insn);
@@ -5394,8 +5776,8 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
 		}
 
 		target_size = 0;
-		cnt = ops->convert_ctx_access(type, insn, insn_buf, env->prog,
-					      &target_size);
+		cnt = convert_ctx_access(type, insn, insn_buf, env->prog,
+					 &target_size);
 		if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf) ||
 		    (ctx_field_size && !target_size)) {
 			verbose(env, "bpf verifier is misconfigured\n");

net/core/filter.c

@@ -58,13 +58,17 @@
 #include <net/busy_poll.h>
 #include <net/tcp.h>
 #include <net/xfrm.h>
+#include <net/udp.h>
 #include <linux/bpf_trace.h>
 #include <net/xdp_sock.h>
 #include <linux/inetdevice.h>
+#include <net/inet_hashtables.h>
+#include <net/inet6_hashtables.h>
 #include <net/ip_fib.h>
 #include <net/flow.h>
 #include <net/arp.h>
 #include <net/ipv6.h>
+#include <net/net_namespace.h>
 #include <linux/seg6_local.h>
 #include <net/seg6.h>
 #include <net/seg6_local.h>
@@ -4813,6 +4817,141 @@ static const struct bpf_func_proto bpf_lwt_seg6_adjust_srh_proto = {
 };
 #endif /* CONFIG_IPV6_SEG6_BPF */
 
+struct sock *sk_lookup(struct net *net, struct bpf_sock_tuple *tuple,
+		       struct sk_buff *skb, u8 family, u8 proto)
+{
+	int dif = skb->dev->ifindex;
+	bool refcounted = false;
+	struct sock *sk = NULL;
+
+	if (family == AF_INET) {
+		__be32 src4 = tuple->ipv4.saddr;
+		__be32 dst4 = tuple->ipv4.daddr;
+		int sdif = inet_sdif(skb);
+
+		if (proto == IPPROTO_TCP)
+			sk = __inet_lookup(net, &tcp_hashinfo, skb, 0,
+					   src4, tuple->ipv4.sport,
+					   dst4, tuple->ipv4.dport,
+					   dif, sdif, &refcounted);
+		else
+			sk = __udp4_lib_lookup(net, src4, tuple->ipv4.sport,
+					       dst4, tuple->ipv4.dport,
+					       dif, sdif, &udp_table, skb);
+#if IS_ENABLED(CONFIG_IPV6)
+	} else {
+		struct in6_addr *src6 = (struct in6_addr *)&tuple->ipv6.saddr;
+		struct in6_addr *dst6 = (struct in6_addr *)&tuple->ipv6.daddr;
+		int sdif = inet6_sdif(skb);
+
+		if (proto == IPPROTO_TCP)
+			sk = __inet6_lookup(net, &tcp_hashinfo, skb, 0,
+					    src6, tuple->ipv6.sport,
+					    dst6, tuple->ipv6.dport,
+					    dif, sdif, &refcounted);
+		else
+			sk = __udp6_lib_lookup(net, src6, tuple->ipv6.sport,
+					       dst6, tuple->ipv6.dport,
+					       dif, sdif, &udp_table, skb);
+#endif
+	}
+
+	if (unlikely(sk && !refcounted && !sock_flag(sk, SOCK_RCU_FREE))) {
+		WARN_ONCE(1, "Found non-RCU, unreferenced socket!");
+		sk = NULL;
+	}
+	return sk;
+}
+
+/* bpf_sk_lookup performs the core lookup for different types of sockets,
+ * taking a reference on the socket if it doesn't have the flag SOCK_RCU_FREE.
+ * Returns the socket as an 'unsigned long' to simplify the casting in the
+ * callers to satisfy BPF_CALL declarations.
+ */
+static unsigned long
+bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
+	      u8 proto, u64 netns_id, u64 flags)
+{
+	struct net *caller_net;
+	struct sock *sk = NULL;
+	u8 family = AF_UNSPEC;
+	struct net *net;
+
+	family = len == sizeof(tuple->ipv4) ? AF_INET : AF_INET6;
+	if (unlikely(family == AF_UNSPEC || netns_id > U32_MAX || flags))
+		goto out;
+
+	if (skb->dev)
+		caller_net = dev_net(skb->dev);
+	else
+		caller_net = sock_net(skb->sk);
+	if (netns_id) {
+		net = get_net_ns_by_id(caller_net, netns_id);
+		if (unlikely(!net))
+			goto out;
+		sk = sk_lookup(net, tuple, skb, family, proto);
+		put_net(net);
+	} else {
+		net = caller_net;
+		sk = sk_lookup(net, tuple, skb, family, proto);
+	}
+
+	if (sk)
+		sk = sk_to_full_sk(sk);
+out:
+	return (unsigned long) sk;
+}
+
+BPF_CALL_5(bpf_sk_lookup_tcp, struct sk_buff *, skb,
+	   struct bpf_sock_tuple *, tuple, u32, len, u64, netns_id, u64, flags)
+{
+	return bpf_sk_lookup(skb, tuple, len, IPPROTO_TCP, netns_id, flags);
+}
+
+static const struct bpf_func_proto bpf_sk_lookup_tcp_proto = {
+	.func		= bpf_sk_lookup_tcp,
+	.gpl_only	= false,
+	.pkt_access	= true,
+	.ret_type	= RET_PTR_TO_SOCKET_OR_NULL,
+	.arg1_type	= ARG_PTR_TO_CTX,
+	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg3_type	= ARG_CONST_SIZE,
+	.arg4_type	= ARG_ANYTHING,
+	.arg5_type	= ARG_ANYTHING,
+};
+
+BPF_CALL_5(bpf_sk_lookup_udp, struct sk_buff *, skb,
+	   struct bpf_sock_tuple *, tuple, u32, len, u64, netns_id, u64, flags)
+{
+	return bpf_sk_lookup(skb, tuple, len, IPPROTO_UDP, netns_id, flags);
+}
+
+static const struct bpf_func_proto bpf_sk_lookup_udp_proto = {
+	.func		= bpf_sk_lookup_udp,
+	.gpl_only	= false,
+	.pkt_access	= true,
+	.ret_type	= RET_PTR_TO_SOCKET_OR_NULL,
+	.arg1_type	= ARG_PTR_TO_CTX,
+	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg3_type	= ARG_CONST_SIZE,
+	.arg4_type	= ARG_ANYTHING,
+	.arg5_type	= ARG_ANYTHING,
+};
+
+BPF_CALL_1(bpf_sk_release, struct sock *, sk)
+{
+	if (!sock_flag(sk, SOCK_RCU_FREE))
+		sock_gen_put(sk);
+	return 0;
+}
+
+static const struct bpf_func_proto bpf_sk_release_proto = {
+	.func		= bpf_sk_release,
+	.gpl_only	= false,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_SOCKET,
+};
+
 bool bpf_helper_changes_pkt_data(void *func)
 {
 	if (func == bpf_skb_vlan_push ||
@@ -5019,6 +5158,12 @@ tc_cls_act_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 	case BPF_FUNC_skb_ancestor_cgroup_id:
 		return &bpf_skb_ancestor_cgroup_id_proto;
 #endif
+	case BPF_FUNC_sk_lookup_tcp:
+		return &bpf_sk_lookup_tcp_proto;
+	case BPF_FUNC_sk_lookup_udp:
+		return &bpf_sk_lookup_udp_proto;
+	case BPF_FUNC_sk_release:
+		return &bpf_sk_release_proto;
 	default:
 		return bpf_base_func_proto(func_id);
 	}
@@ -5119,6 +5264,12 @@ sk_skb_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_sk_redirect_hash_proto;
 	case BPF_FUNC_get_local_storage:
 		return &bpf_get_local_storage_proto;
+	case BPF_FUNC_sk_lookup_tcp:
+		return &bpf_sk_lookup_tcp_proto;
+	case BPF_FUNC_sk_lookup_udp:
+		return &bpf_sk_lookup_udp_proto;
+	case BPF_FUNC_sk_release:
+		return &bpf_sk_release_proto;
 	default:
 		return bpf_base_func_proto(func_id);
 	}
@@ -5394,23 +5545,29 @@ static bool __sock_filter_check_size(int off, int size,
 	return size == size_default;
 }
 
-static bool sock_filter_is_valid_access(int off, int size,
-					enum bpf_access_type type,
-					const struct bpf_prog *prog,
-					struct bpf_insn_access_aux *info)
+bool bpf_sock_is_valid_access(int off, int size, enum bpf_access_type type,
+			      struct bpf_insn_access_aux *info)
 {
 	if (off < 0 || off >= sizeof(struct bpf_sock))
 		return false;
 	if (off % size != 0)
 		return false;
-	if (!__sock_filter_check_attach_type(off, type,
-					     prog->expected_attach_type))
-		return false;
 	if (!__sock_filter_check_size(off, size, info))
 		return false;
 	return true;
 }
 
+static bool sock_filter_is_valid_access(int off, int size,
+					enum bpf_access_type type,
+					const struct bpf_prog *prog,
+					struct bpf_insn_access_aux *info)
+{
+	if (!bpf_sock_is_valid_access(off, size, type, info))
+		return false;
+	return __sock_filter_check_attach_type(off, type,
+					       prog->expected_attach_type);
+}
+
 static int bpf_unclone_prologue(struct bpf_insn *insn_buf, bool direct_write,
 				const struct bpf_prog *prog, int drop_verdict)
 {
@@ -6122,10 +6279,10 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type,
 	return insn - insn_buf;
 }
 
-static u32 sock_filter_convert_ctx_access(enum bpf_access_type type,
-					  const struct bpf_insn *si,
-					  struct bpf_insn *insn_buf,
-					  struct bpf_prog *prog, u32 *target_size)
+u32 bpf_sock_convert_ctx_access(enum bpf_access_type type,
+				const struct bpf_insn *si,
+				struct bpf_insn *insn_buf,
+				struct bpf_prog *prog, u32 *target_size)
 {
 	struct bpf_insn *insn = insn_buf;
 	int off;
@@ -7037,7 +7194,7 @@ const struct bpf_prog_ops lwt_seg6local_prog_ops = {
 const struct bpf_verifier_ops cg_sock_verifier_ops = {
 	.get_func_proto		= sock_filter_func_proto,
 	.is_valid_access	= sock_filter_is_valid_access,
-	.convert_ctx_access	= sock_filter_convert_ctx_access,
+	.convert_ctx_access	= bpf_sock_convert_ctx_access,
 };
 
 const struct bpf_prog_ops cg_sock_prog_ops = {

tools/include/uapi/linux/bpf.h

@@ -2144,6 +2144,77 @@ union bpf_attr {
  *		request in the skb.
  *	Return
  *		0 on success, or a negative error in case of failure.
+ *
+ * struct bpf_sock *bpf_sk_lookup_tcp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u32 netns, u64 flags)
+ *	Description
+ *		Look for TCP socket matching *tuple*, optionally in a child
+ *		network namespace *netns*. The return value must be checked,
+ *		and if non-NULL, released via **bpf_sk_release**\ ().
+ *
+ *		The *ctx* should point to the context of the program, such as
+ *		the skb or socket (depending on the hook in use). This is used
+ *		to determine the base network namespace for the lookup.
+ *
+ *		*tuple_size* must be one of:
+ *
+ *		**sizeof**\ (*tuple*\ **->ipv4**)
+ *			Look for an IPv4 socket.
+ *		**sizeof**\ (*tuple*\ **->ipv6**)
+ *			Look for an IPv6 socket.
+ *
+ *		If the *netns* is zero, then the socket lookup table in the
+ *		netns associated with the *ctx* will be used. For the TC hooks,
+ *		this in the netns of the device in the skb. For socket hooks,
+ *		this in the netns of the socket. If *netns* is non-zero, then
+ *		it specifies the ID of the netns relative to the netns
+ *		associated with the *ctx*.
+ *
+ *		All values for *flags* are reserved for future usage, and must
+ *		be left at zero.
+ *
+ *		This helper is available only if the kernel was compiled with
+ *		**CONFIG_NET** configuration option.
+ *	Return
+ *		Pointer to *struct bpf_sock*, or NULL in case of failure.
+ *
+ * struct bpf_sock *bpf_sk_lookup_udp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u32 netns, u64 flags)
+ *	Description
+ *		Look for UDP socket matching *tuple*, optionally in a child
+ *		network namespace *netns*. The return value must be checked,
+ *		and if non-NULL, released via **bpf_sk_release**\ ().
+ *
+ *		The *ctx* should point to the context of the program, such as
+ *		the skb or socket (depending on the hook in use). This is used
+ *		to determine the base network namespace for the lookup.
+ *
+ *		*tuple_size* must be one of:
+ *
+ *		**sizeof**\ (*tuple*\ **->ipv4**)
+ *			Look for an IPv4 socket.
+ *		**sizeof**\ (*tuple*\ **->ipv6**)
+ *			Look for an IPv6 socket.
+ *
+ *		If the *netns* is zero, then the socket lookup table in the
+ *		netns associated with the *ctx* will be used. For the TC hooks,
+ *		this in the netns of the device in the skb. For socket hooks,
+ *		this in the netns of the socket. If *netns* is non-zero, then
+ *		it specifies the ID of the netns relative to the netns
+ *		associated with the *ctx*.
+ *
+ *		All values for *flags* are reserved for future usage, and must
+ *		be left at zero.
+ *
+ *		This helper is available only if the kernel was compiled with
+ *		**CONFIG_NET** configuration option.
+ *	Return
+ *		Pointer to *struct bpf_sock*, or NULL in case of failure.
+ *
+ * int bpf_sk_release(struct bpf_sock *sk)
+ *	Description
+ *		Release the reference held by *sock*. *sock* must be a non-NULL
+ *		pointer that was returned from bpf_sk_lookup_xxx\ ().
+ *	Return
+ *		0 on success, or a negative error in case of failure.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -2229,7 +2300,10 @@ union bpf_attr {
 	FN(get_current_cgroup_id),	\
 	FN(get_local_storage),		\
 	FN(sk_select_reuseport),	\
-	FN(skb_ancestor_cgroup_id),
+	FN(skb_ancestor_cgroup_id),	\
+	FN(sk_lookup_tcp),		\
+	FN(sk_lookup_udp),		\
+	FN(sk_release),
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
  * function eBPF program intends to call
@@ -2399,6 +2473,23 @@ struct bpf_sock {
 				 */
 };
 
+struct bpf_sock_tuple {
+	union {
+		struct {
+			__be32 saddr;
+			__be32 daddr;
+			__be16 sport;
+			__be16 dport;
+		} ipv4;
+		struct {
+			__be32 saddr[4];
+			__be32 daddr[4];
+			__be16 sport;
+			__be16 dport;
+		} ipv6;
+	};
+};
+
 #define XDP_PACKET_HEADROOM 256
 
 /* User return codes for XDP prog type.

tools/lib/bpf/libbpf.c

@@ -228,7 +228,7 @@ struct bpf_object {
 };
 #define obj_elf_valid(o)	((o)->efile.elf)
 
-static void bpf_program__unload(struct bpf_program *prog)
+void bpf_program__unload(struct bpf_program *prog)
 {
 	int i;
 
@@ -1375,7 +1375,7 @@ out:
 	return ret;
 }
 
-static int
+int
 bpf_program__load(struct bpf_program *prog,
 		  char *license, u32 kern_version)
 {

tools/lib/bpf/libbpf.h

@@ -128,10 +128,13 @@ void bpf_program__set_ifindex(struct bpf_program *prog, __u32 ifindex);
 
 const char *bpf_program__title(struct bpf_program *prog, bool needs_copy);
 
+int bpf_program__load(struct bpf_program *prog, char *license,
+		      u32 kern_version);
 int bpf_program__fd(struct bpf_program *prog);
 int bpf_program__pin_instance(struct bpf_program *prog, const char *path,
 			      int instance);
 int bpf_program__pin(struct bpf_program *prog, const char *path);
+void bpf_program__unload(struct bpf_program *prog);
 
 struct bpf_insn;
 

tools/testing/selftests/bpf/Makefile

@@ -36,7 +36,7 @@ TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test
 	test_get_stack_rawtp.o test_sockmap_kern.o test_sockhash_kern.o \
 	test_lwt_seg6local.o sendmsg4_prog.o sendmsg6_prog.o test_lirc_mode2_kern.o \
 	get_cgroup_id_kern.o socket_cookie_prog.o test_select_reuseport_kern.o \
-	test_skb_cgroup_id_kern.o bpf_flow.o netcnt_prog.o
+	test_skb_cgroup_id_kern.o bpf_flow.o netcnt_prog.o test_sk_lookup_kern.o
 
 # Order correspond to 'make run_tests' order
 TEST_PROGS := test_kmod.sh \

tools/testing/selftests/bpf/bpf_helpers.h

@@ -143,6 +143,18 @@ static unsigned long long (*bpf_skb_cgroup_id)(void *ctx) =
 	(void *) BPF_FUNC_skb_cgroup_id;
 static unsigned long long (*bpf_skb_ancestor_cgroup_id)(void *ctx, int level) =
 	(void *) BPF_FUNC_skb_ancestor_cgroup_id;
+static struct bpf_sock *(*bpf_sk_lookup_tcp)(void *ctx,
+					     struct bpf_sock_tuple *tuple,
+					     int size, unsigned int netns_id,
+					     unsigned long long flags) =
+	(void *) BPF_FUNC_sk_lookup_tcp;
+static struct bpf_sock *(*bpf_sk_lookup_udp)(void *ctx,
+					     struct bpf_sock_tuple *tuple,
+					     int size, unsigned int netns_id,
+					     unsigned long long flags) =
+	(void *) BPF_FUNC_sk_lookup_udp;
+static int (*bpf_sk_release)(struct bpf_sock *sk) =
+	(void *) BPF_FUNC_sk_release;
 
 /* llvm builtin functions that eBPF C program may use to
  * emit BPF_LD_ABS and BPF_LD_IND instructions

tools/testing/selftests/bpf/test_progs.c

@@ -1698,6 +1698,43 @@ static void test_task_fd_query_tp(void)
 				   "sys_enter_read");
 }
 
+static void test_reference_tracking()
+{
+	const char *file = "./test_sk_lookup_kern.o";
+	struct bpf_object *obj;
+	struct bpf_program *prog;
+	__u32 duration;
+	int err = 0;
+
+	obj = bpf_object__open(file);
+	if (IS_ERR(obj)) {
+		error_cnt++;
+		return;
+	}
+
+	bpf_object__for_each_program(prog, obj) {
+		const char *title;
+
+		/* Ignore .text sections */
+		title = bpf_program__title(prog, false);
+		if (strstr(title, ".text") != NULL)
+			continue;
+
+		bpf_program__set_type(prog, BPF_PROG_TYPE_SCHED_CLS);
+
+		/* Expect verifier failure if test name has 'fail' */
+		if (strstr(title, "fail") != NULL) {
+			libbpf_set_print(NULL, NULL, NULL);
+			err = !bpf_program__load(prog, "GPL", 0);
+			libbpf_set_print(printf, printf, NULL);
+		} else {
+			err = bpf_program__load(prog, "GPL", 0);
+		}
+		CHECK(err, title, "\n");
+	}
+	bpf_object__close(obj);
+}
+
 int main(void)
 {
 	jit_enabled = is_jit_enabled();
@@ -1719,6 +1756,7 @@ int main(void)
 	test_get_stack_raw_tp();
 	test_task_fd_query_rawtp();
 	test_task_fd_query_tp();
+	test_reference_tracking();
 
 	printf("Summary: %d PASSED, %d FAILED\n", pass_cnt, error_cnt);
 	return error_cnt ? EXIT_FAILURE : EXIT_SUCCESS;

tools/testing/selftests/bpf/test_sk_lookup_kern.c

@@ -0,0 +1,180 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+// Copyright (c) 2018 Covalent IO, Inc. http://covalent.io
+
+#include <stddef.h>
+#include <stdbool.h>
+#include <string.h>
+#include <linux/bpf.h>
+#include <linux/if_ether.h>
+#include <linux/in.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <linux/pkt_cls.h>
+#include <linux/tcp.h>
+#include <sys/socket.h>
+#include "bpf_helpers.h"
+#include "bpf_endian.h"
+
+int _version SEC("version") = 1;
+char _license[] SEC("license") = "GPL";
+
+/* Fill 'tuple' with L3 info, and attempt to find L4. On fail, return NULL. */
+static struct bpf_sock_tuple *get_tuple(void *data, __u64 nh_off,
+					void *data_end, __u16 eth_proto,
+					bool *ipv4)
+{
+	struct bpf_sock_tuple *result;
+	__u8 proto = 0;
+	__u64 ihl_len;
+
+	if (eth_proto == bpf_htons(ETH_P_IP)) {
+		struct iphdr *iph = (struct iphdr *)(data + nh_off);
+
+		if (iph + 1 > data_end)
+			return NULL;
+		ihl_len = iph->ihl * 4;
+		proto = iph->protocol;
+		*ipv4 = true;
+		result = (struct bpf_sock_tuple *)&iph->saddr;
+	} else if (eth_proto == bpf_htons(ETH_P_IPV6)) {
+		struct ipv6hdr *ip6h = (struct ipv6hdr *)(data + nh_off);
+
+		if (ip6h + 1 > data_end)
+			return NULL;
+		ihl_len = sizeof(*ip6h);
+		proto = ip6h->nexthdr;
+		*ipv4 = true;
+		result = (struct bpf_sock_tuple *)&ip6h->saddr;
+	}
+
+	if (data + nh_off + ihl_len > data_end || proto != IPPROTO_TCP)
+		return NULL;
+
+	return result;
+}
+
+SEC("sk_lookup_success")
+int bpf_sk_lookup_test0(struct __sk_buff *skb)
+{
+	void *data_end = (void *)(long)skb->data_end;
+	void *data = (void *)(long)skb->data;
+	struct ethhdr *eth = (struct ethhdr *)(data);
+	struct bpf_sock_tuple *tuple;
+	struct bpf_sock *sk;
+	size_t tuple_len;
+	bool ipv4;
+
+	if (eth + 1 > data_end)
+		return TC_ACT_SHOT;
+
+	tuple = get_tuple(data, sizeof(*eth), data_end, eth->h_proto, &ipv4);
+	if (!tuple || tuple + sizeof *tuple > data_end)
+		return TC_ACT_SHOT;
+
+	tuple_len = ipv4 ? sizeof(tuple->ipv4) : sizeof(tuple->ipv6);
+	sk = bpf_sk_lookup_tcp(skb, tuple, tuple_len, 0, 0);
+	if (sk)
+		bpf_sk_release(sk);
+	return sk ? TC_ACT_OK : TC_ACT_UNSPEC;
+}
+
+SEC("sk_lookup_success_simple")
+int bpf_sk_lookup_test1(struct __sk_buff *skb)
+{
+	struct bpf_sock_tuple tuple = {};
+	struct bpf_sock *sk;
+
+	sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), 0, 0);
+	if (sk)
+		bpf_sk_release(sk);
+	return 0;
+}
+
+SEC("fail_use_after_free")
+int bpf_sk_lookup_uaf(struct __sk_buff *skb)
+{
+	struct bpf_sock_tuple tuple = {};
+	struct bpf_sock *sk;
+	__u32 family = 0;
+
+	sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), 0, 0);
+	if (sk) {
+		bpf_sk_release(sk);
+		family = sk->family;
+	}
+	return family;
+}
+
+SEC("fail_modify_sk_pointer")
+int bpf_sk_lookup_modptr(struct __sk_buff *skb)
+{
+	struct bpf_sock_tuple tuple = {};
+	struct bpf_sock *sk;
+	__u32 family;
+
+	sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), 0, 0);
+	if (sk) {
+		sk += 1;
+		bpf_sk_release(sk);
+	}
+	return 0;
+}
+
+SEC("fail_modify_sk_or_null_pointer")
+int bpf_sk_lookup_modptr_or_null(struct __sk_buff *skb)
+{
+	struct bpf_sock_tuple tuple = {};
+	struct bpf_sock *sk;
+	__u32 family;
+
+	sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), 0, 0);
+	sk += 1;
+	if (sk)
+		bpf_sk_release(sk);
+	return 0;
+}
+
+SEC("fail_no_release")
+int bpf_sk_lookup_test2(struct __sk_buff *skb)
+{
+	struct bpf_sock_tuple tuple = {};
+
+	bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), 0, 0);
+	return 0;
+}
+
+SEC("fail_release_twice")
+int bpf_sk_lookup_test3(struct __sk_buff *skb)
+{
+	struct bpf_sock_tuple tuple = {};
+	struct bpf_sock *sk;
+
+	sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), 0, 0);
+	bpf_sk_release(sk);
+	bpf_sk_release(sk);
+	return 0;
+}
+
+SEC("fail_release_unchecked")
+int bpf_sk_lookup_test4(struct __sk_buff *skb)
+{
+	struct bpf_sock_tuple tuple = {};
+	struct bpf_sock *sk;
+
+	sk = bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), 0, 0);
+	bpf_sk_release(sk);
+	return 0;
+}
+
+void lookup_no_release(struct __sk_buff *skb)
+{
+	struct bpf_sock_tuple tuple = {};
+	bpf_sk_lookup_tcp(skb, &tuple, sizeof(tuple), 0, 0);
+}
+
+SEC("fail_no_release_subcall")
+int bpf_sk_lookup_test5(struct __sk_buff *skb)
+{
+	lookup_no_release(skb);
+	return 0;
+}

tools/testing/selftests/bpf/test_verifier.c

@@ -3,6 +3,7 @@
  *
  * Copyright (c) 2014 PLUMgrid, http://plumgrid.com
  * Copyright (c) 2017 Facebook
+ * Copyright (c) 2018 Covalent IO, Inc. http://covalent.io
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of version 2 of the GNU General Public
@@ -178,6 +179,24 @@ static void bpf_fill_rand_ld_dw(struct bpf_test *self)
 	self->retval = (uint32_t)res;
 }
 
+/* BPF_SK_LOOKUP contains 13 instructions, if you need to fix up maps */
+#define BPF_SK_LOOKUP							\
+	/* struct bpf_sock_tuple tuple = {} */				\
+	BPF_MOV64_IMM(BPF_REG_2, 0),					\
+	BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_2, -8),			\
+	BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_2, -16),		\
+	BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_2, -24),		\
+	BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_2, -32),		\
+	BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_2, -40),		\
+	BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_2, -48),		\
+	/* sk = sk_lookup_tcp(ctx, &tuple, sizeof tuple, 0, 0) */	\
+	BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),				\
+	BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -48),				\
+	BPF_MOV64_IMM(BPF_REG_3, sizeof(struct bpf_sock_tuple)),	\
+	BPF_MOV64_IMM(BPF_REG_4, 0),					\
+	BPF_MOV64_IMM(BPF_REG_5, 0),					\
+	BPF_EMIT_CALL(BPF_FUNC_sk_lookup_tcp)
+
 static struct bpf_test tests[] = {
 	{
 		"add+sub+mul",
@@ -2707,6 +2726,137 @@ static struct bpf_test tests[] = {
 		.errstr = "same insn cannot be used with different pointers",
 		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
 	},
+	{
+		"unpriv: spill/fill of different pointers stx - ctx and sock",
+		.insns = {
+			BPF_MOV64_REG(BPF_REG_8, BPF_REG_1),
+			/* struct bpf_sock *sock = bpf_sock_lookup(...); */
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_2, BPF_REG_0),
+			/* u64 foo; */
+			/* void *target = &foo; */
+			BPF_ALU64_REG(BPF_MOV, BPF_REG_6, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_6, -8),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_8),
+			/* if (skb == NULL) *target = sock; */
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 1),
+				BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_2, 0),
+			/* else *target = skb; */
+			BPF_JMP_IMM(BPF_JNE, BPF_REG_1, 0, 1),
+				BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, 0),
+			/* struct __sk_buff *skb = *target; */
+			BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_6, 0),
+			/* skb->mark = 42; */
+			BPF_MOV64_IMM(BPF_REG_3, 42),
+			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_3,
+				    offsetof(struct __sk_buff, mark)),
+			/* if (sk) bpf_sk_release(sk) */
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 1),
+				BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+		},
+		.result = REJECT,
+		.errstr = "type=ctx expected=sock",
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+	},
+	{
+		"unpriv: spill/fill of different pointers stx - leak sock",
+		.insns = {
+			BPF_MOV64_REG(BPF_REG_8, BPF_REG_1),
+			/* struct bpf_sock *sock = bpf_sock_lookup(...); */
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_2, BPF_REG_0),
+			/* u64 foo; */
+			/* void *target = &foo; */
+			BPF_ALU64_REG(BPF_MOV, BPF_REG_6, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_6, -8),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_8),
+			/* if (skb == NULL) *target = sock; */
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 1),
+				BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_2, 0),
+			/* else *target = skb; */
+			BPF_JMP_IMM(BPF_JNE, BPF_REG_1, 0, 1),
+				BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, 0),
+			/* struct __sk_buff *skb = *target; */
+			BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_6, 0),
+			/* skb->mark = 42; */
+			BPF_MOV64_IMM(BPF_REG_3, 42),
+			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_3,
+				    offsetof(struct __sk_buff, mark)),
+			BPF_EXIT_INSN(),
+		},
+		.result = REJECT,
+		//.errstr = "same insn cannot be used with different pointers",
+		.errstr = "Unreleased reference",
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+	},
+	{
+		"unpriv: spill/fill of different pointers stx - sock and ctx (read)",
+		.insns = {
+			BPF_MOV64_REG(BPF_REG_8, BPF_REG_1),
+			/* struct bpf_sock *sock = bpf_sock_lookup(...); */
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_2, BPF_REG_0),
+			/* u64 foo; */
+			/* void *target = &foo; */
+			BPF_ALU64_REG(BPF_MOV, BPF_REG_6, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_6, -8),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_8),
+			/* if (skb) *target = skb */
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 1),
+				BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, 0),
+			/* else *target = sock */
+			BPF_JMP_IMM(BPF_JNE, BPF_REG_1, 0, 1),
+				BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_2, 0),
+			/* struct bpf_sock *sk = *target; */
+			BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_6, 0),
+			/* if (sk) u32 foo = sk->mark; bpf_sk_release(sk); */
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 2),
+				BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+					    offsetof(struct bpf_sock, mark)),
+				BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+		},
+		.result = REJECT,
+		.errstr = "same insn cannot be used with different pointers",
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+	},
+	{
+		"unpriv: spill/fill of different pointers stx - sock and ctx (write)",
+		.insns = {
+			BPF_MOV64_REG(BPF_REG_8, BPF_REG_1),
+			/* struct bpf_sock *sock = bpf_sock_lookup(...); */
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_2, BPF_REG_0),
+			/* u64 foo; */
+			/* void *target = &foo; */
+			BPF_ALU64_REG(BPF_MOV, BPF_REG_6, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_6, -8),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_8),
+			/* if (skb) *target = skb */
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 1),
+				BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, 0),
+			/* else *target = sock */
+			BPF_JMP_IMM(BPF_JNE, BPF_REG_1, 0, 1),
+				BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_2, 0),
+			/* struct bpf_sock *sk = *target; */
+			BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_6, 0),
+			/* if (sk) sk->mark = 42; bpf_sk_release(sk); */
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 3),
+				BPF_MOV64_IMM(BPF_REG_3, 42),
+				BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_3,
+					    offsetof(struct bpf_sock, mark)),
+				BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+		},
+		.result = REJECT,
+		//.errstr = "same insn cannot be used with different pointers",
+		.errstr = "cannot write into socket",
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+	},
 	{
 		"unpriv: spill/fill of different pointers ldx",
 		.insns = {
@@ -3276,7 +3426,7 @@ static struct bpf_test tests[] = {
 			BPF_ST_MEM(BPF_DW, BPF_REG_1, offsetof(struct __sk_buff, mark), 0),
 			BPF_EXIT_INSN(),
 		},
-		.errstr = "BPF_ST stores into R1 context is not allowed",
+		.errstr = "BPF_ST stores into R1 inv is not allowed",
 		.result = REJECT,
 		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
 	},
@@ -3288,7 +3438,7 @@ static struct bpf_test tests[] = {
 				     BPF_REG_0, offsetof(struct __sk_buff, mark), 0),
 			BPF_EXIT_INSN(),
 		},
-		.errstr = "BPF_XADD stores into R1 context is not allowed",
+		.errstr = "BPF_XADD stores into R1 inv is not allowed",
 		.result = REJECT,
 		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
 	},
@@ -3638,7 +3788,7 @@ static struct bpf_test tests[] = {
 			BPF_MOV64_IMM(BPF_REG_0, 0),
 			BPF_EXIT_INSN(),
 		},
-		.errstr = "R3 pointer arithmetic on PTR_TO_PACKET_END",
+		.errstr = "R3 pointer arithmetic on pkt_end",
 		.result = REJECT,
 		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
 	},
@@ -4896,7 +5046,7 @@ static struct bpf_test tests[] = {
 			BPF_EXIT_INSN(),
 		},
 		.fixup_map1 = { 4 },
-		.errstr = "R4 pointer arithmetic on PTR_TO_MAP_VALUE_OR_NULL",
+		.errstr = "R4 pointer arithmetic on map_value_or_null",
 		.result = REJECT,
 		.prog_type = BPF_PROG_TYPE_SCHED_CLS
 	},
@@ -4917,7 +5067,7 @@ static struct bpf_test tests[] = {
 			BPF_EXIT_INSN(),
 		},
 		.fixup_map1 = { 4 },
-		.errstr = "R4 pointer arithmetic on PTR_TO_MAP_VALUE_OR_NULL",
+		.errstr = "R4 pointer arithmetic on map_value_or_null",
 		.result = REJECT,
 		.prog_type = BPF_PROG_TYPE_SCHED_CLS
 	},
@@ -4938,7 +5088,7 @@ static struct bpf_test tests[] = {
 			BPF_EXIT_INSN(),
 		},
 		.fixup_map1 = { 4 },
-		.errstr = "R4 pointer arithmetic on PTR_TO_MAP_VALUE_OR_NULL",
+		.errstr = "R4 pointer arithmetic on map_value_or_null",
 		.result = REJECT,
 		.prog_type = BPF_PROG_TYPE_SCHED_CLS
 	},
@@ -5266,7 +5416,7 @@ static struct bpf_test tests[] = {
 		.errstr_unpriv = "R2 leaks addr into mem",
 		.result_unpriv = REJECT,
 		.result = REJECT,
-		.errstr = "BPF_XADD stores into R1 context is not allowed",
+		.errstr = "BPF_XADD stores into R1 inv is not allowed",
 	},
 	{
 		"leak pointer into ctx 2",
@@ -5281,7 +5431,7 @@ static struct bpf_test tests[] = {
 		.errstr_unpriv = "R10 leaks addr into mem",
 		.result_unpriv = REJECT,
 		.result = REJECT,
-		.errstr = "BPF_XADD stores into R1 context is not allowed",
+		.errstr = "BPF_XADD stores into R1 inv is not allowed",
 	},
 	{
 		"leak pointer into ctx 3",
@@ -7253,7 +7403,7 @@ static struct bpf_test tests[] = {
 			BPF_EXIT_INSN(),
 		},
 		.fixup_map_in_map = { 3 },
-		.errstr = "R1 pointer arithmetic on CONST_PTR_TO_MAP prohibited",
+		.errstr = "R1 pointer arithmetic on map_ptr prohibited",
 		.result = REJECT,
 	},
 	{
@@ -8927,7 +9077,7 @@ static struct bpf_test tests[] = {
 			BPF_MOV64_IMM(BPF_REG_0, 0),
 			BPF_EXIT_INSN(),
 		},
-		.errstr = "R3 pointer arithmetic on PTR_TO_PACKET_END",
+		.errstr = "R3 pointer arithmetic on pkt_end",
 		.result = REJECT,
 		.prog_type = BPF_PROG_TYPE_XDP,
 	},
@@ -8946,7 +9096,7 @@ static struct bpf_test tests[] = {
 			BPF_MOV64_IMM(BPF_REG_0, 0),
 			BPF_EXIT_INSN(),
 		},
-		.errstr = "R3 pointer arithmetic on PTR_TO_PACKET_END",
+		.errstr = "R3 pointer arithmetic on pkt_end",
 		.result = REJECT,
 		.prog_type = BPF_PROG_TYPE_XDP,
 	},
@@ -12230,7 +12380,7 @@ static struct bpf_test tests[] = {
 			BPF_EXIT_INSN(),
 		},
 		.result = REJECT,
-		.errstr = "BPF_XADD stores into R2 packet",
+		.errstr = "BPF_XADD stores into R2 ctx",
 		.prog_type = BPF_PROG_TYPE_XDP,
 	},
 	{
@@ -12557,6 +12707,214 @@ static struct bpf_test tests[] = {
 		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
 		.result = ACCEPT,
 	},
+	{
+		"reference tracking: leak potential reference",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_6, BPF_REG_0), /* leak reference */
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "Unreleased reference",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: leak potential reference on stack",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_4, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, -8),
+			BPF_STX_MEM(BPF_DW, BPF_REG_4, BPF_REG_0, 0),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "Unreleased reference",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: leak potential reference on stack 2",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_4, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, -8),
+			BPF_STX_MEM(BPF_DW, BPF_REG_4, BPF_REG_0, 0),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_ST_MEM(BPF_DW, BPF_REG_4, 0, 0),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "Unreleased reference",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: zero potential reference",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_IMM(BPF_REG_0, 0), /* leak reference */
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "Unreleased reference",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: copy and zero potential references",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_7, BPF_REG_0),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_MOV64_IMM(BPF_REG_7, 0), /* leak reference */
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "Unreleased reference",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: release reference without check",
+		.insns = {
+			BPF_SK_LOOKUP,
+			/* reference in r0 may be NULL */
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_MOV64_IMM(BPF_REG_2, 0),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "type=sock_or_null expected=sock",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: release reference",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.result = ACCEPT,
+	},
+	{
+		"reference tracking: release reference 2",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
+			BPF_EXIT_INSN(),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.result = ACCEPT,
+	},
+	{
+		"reference tracking: release reference twice",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "type=inv expected=sock",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: release reference twice inside branch",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 3), /* goto end */
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "type=inv expected=sock",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: alloc, check, free in one subbranch",
+		.insns = {
+			BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+				    offsetof(struct __sk_buff, data)),
+			BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+				    offsetof(struct __sk_buff, data_end)),
+			BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 16),
+			/* if (offsetof(skb, mark) > data_len) exit; */
+			BPF_JMP_REG(BPF_JLE, BPF_REG_0, BPF_REG_3, 1),
+			BPF_EXIT_INSN(),
+			BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_2,
+				    offsetof(struct __sk_buff, mark)),
+			BPF_SK_LOOKUP,
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 0, 1), /* mark == 0? */
+			/* Leak reference in R0 */
+			BPF_EXIT_INSN(),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2), /* sk NULL? */
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "Unreleased reference",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: alloc, check, free in both subbranches",
+		.insns = {
+			BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+				    offsetof(struct __sk_buff, data)),
+			BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+				    offsetof(struct __sk_buff, data_end)),
+			BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 16),
+			/* if (offsetof(skb, mark) > data_len) exit; */
+			BPF_JMP_REG(BPF_JLE, BPF_REG_0, BPF_REG_3, 1),
+			BPF_EXIT_INSN(),
+			BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_2,
+				    offsetof(struct __sk_buff, mark)),
+			BPF_SK_LOOKUP,
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 0, 4), /* mark == 0? */
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2), /* sk NULL? */
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2), /* sk NULL? */
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.result = ACCEPT,
+	},
+	{
+		"reference tracking in call: free reference in subprog",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0), /* unchecked reference */
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 2),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+
+			/* subprog 1 */
+			BPF_MOV64_REG(BPF_REG_2, BPF_REG_1),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_2, 0, 1),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.result = ACCEPT,
+	},
 	{
 		"pass modified ctx pointer to helper, 1",
 		.insns = {
@@ -12627,6 +12985,407 @@ static struct bpf_test tests[] = {
 		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
 		.result = ACCEPT,
 	},
+	{
+		"reference tracking in call: free reference in subprog and outside",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0), /* unchecked reference */
+			BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 3),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+
+			/* subprog 1 */
+			BPF_MOV64_REG(BPF_REG_2, BPF_REG_1),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_2, 0, 1),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "type=inv expected=sock",
+		.result = REJECT,
+	},
+	{
+		"reference tracking in call: alloc & leak reference in subprog",
+		.insns = {
+			BPF_MOV64_REG(BPF_REG_4, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, -8),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 3),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+
+			/* subprog 1 */
+			BPF_MOV64_REG(BPF_REG_6, BPF_REG_4),
+			BPF_SK_LOOKUP,
+			/* spill unchecked sk_ptr into stack of caller */
+			BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_0, 0),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "Unreleased reference",
+		.result = REJECT,
+	},
+	{
+		"reference tracking in call: alloc in subprog, release outside",
+		.insns = {
+			BPF_MOV64_REG(BPF_REG_4, BPF_REG_10),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 4),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+
+			/* subprog 1 */
+			BPF_SK_LOOKUP,
+			BPF_EXIT_INSN(), /* return sk */
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.retval = POINTER_VALUE,
+		.result = ACCEPT,
+	},
+	{
+		"reference tracking in call: sk_ptr leak into caller stack",
+		.insns = {
+			BPF_MOV64_REG(BPF_REG_4, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, -8),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 2),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+
+			/* subprog 1 */
+			BPF_MOV64_REG(BPF_REG_5, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_5, -8),
+			BPF_STX_MEM(BPF_DW, BPF_REG_5, BPF_REG_4, 0),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 5),
+			/* spill unchecked sk_ptr into stack of caller */
+			BPF_MOV64_REG(BPF_REG_5, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_5, -8),
+			BPF_LDX_MEM(BPF_DW, BPF_REG_4, BPF_REG_5, 0),
+			BPF_STX_MEM(BPF_DW, BPF_REG_4, BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+
+			/* subprog 2 */
+			BPF_SK_LOOKUP,
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "Unreleased reference",
+		.result = REJECT,
+	},
+	{
+		"reference tracking in call: sk_ptr spill into caller stack",
+		.insns = {
+			BPF_MOV64_REG(BPF_REG_4, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, -8),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 2),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+
+			/* subprog 1 */
+			BPF_MOV64_REG(BPF_REG_5, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_5, -8),
+			BPF_STX_MEM(BPF_DW, BPF_REG_5, BPF_REG_4, 0),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 8),
+			/* spill unchecked sk_ptr into stack of caller */
+			BPF_MOV64_REG(BPF_REG_5, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_5, -8),
+			BPF_LDX_MEM(BPF_DW, BPF_REG_4, BPF_REG_5, 0),
+			BPF_STX_MEM(BPF_DW, BPF_REG_4, BPF_REG_0, 0),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
+			/* now the sk_ptr is verified, free the reference */
+			BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_4, 0),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+
+			/* subprog 2 */
+			BPF_SK_LOOKUP,
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.result = ACCEPT,
+	},
+	{
+		"reference tracking: allow LD_ABS",
+		.insns = {
+			BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_LD_ABS(BPF_B, 0),
+			BPF_LD_ABS(BPF_H, 0),
+			BPF_LD_ABS(BPF_W, 0),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.result = ACCEPT,
+	},
+	{
+		"reference tracking: forbid LD_ABS while holding reference",
+		.insns = {
+			BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
+			BPF_SK_LOOKUP,
+			BPF_LD_ABS(BPF_B, 0),
+			BPF_LD_ABS(BPF_H, 0),
+			BPF_LD_ABS(BPF_W, 0),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "BPF_LD_[ABS|IND] cannot be mixed with socket references",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: allow LD_IND",
+		.insns = {
+			BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_MOV64_IMM(BPF_REG_7, 1),
+			BPF_LD_IND(BPF_W, BPF_REG_7, -0x200000),
+			BPF_MOV64_REG(BPF_REG_0, BPF_REG_7),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.result = ACCEPT,
+		.retval = 1,
+	},
+	{
+		"reference tracking: forbid LD_IND while holding reference",
+		.insns = {
+			BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_4, BPF_REG_0),
+			BPF_MOV64_IMM(BPF_REG_7, 1),
+			BPF_LD_IND(BPF_W, BPF_REG_7, -0x200000),
+			BPF_MOV64_REG(BPF_REG_0, BPF_REG_7),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_4),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 1),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "BPF_LD_[ABS|IND] cannot be mixed with socket references",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: check reference or tail call",
+		.insns = {
+			BPF_MOV64_REG(BPF_REG_7, BPF_REG_1),
+			BPF_SK_LOOKUP,
+			/* if (sk) bpf_sk_release() */
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_JMP_IMM(BPF_JNE, BPF_REG_1, 0, 7),
+			/* bpf_tail_call() */
+			BPF_MOV64_IMM(BPF_REG_3, 2),
+			BPF_LD_MAP_FD(BPF_REG_2, 0),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+				     BPF_FUNC_tail_call),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.fixup_prog1 = { 17 },
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.result = ACCEPT,
+	},
+	{
+		"reference tracking: release reference then tail call",
+		.insns = {
+			BPF_MOV64_REG(BPF_REG_7, BPF_REG_1),
+			BPF_SK_LOOKUP,
+			/* if (sk) bpf_sk_release() */
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 1),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			/* bpf_tail_call() */
+			BPF_MOV64_IMM(BPF_REG_3, 2),
+			BPF_LD_MAP_FD(BPF_REG_2, 0),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+				     BPF_FUNC_tail_call),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+		},
+		.fixup_prog1 = { 18 },
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.result = ACCEPT,
+	},
+	{
+		"reference tracking: leak possible reference over tail call",
+		.insns = {
+			BPF_MOV64_REG(BPF_REG_7, BPF_REG_1),
+			/* Look up socket and store in REG_6 */
+			BPF_SK_LOOKUP,
+			/* bpf_tail_call() */
+			BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
+			BPF_MOV64_IMM(BPF_REG_3, 2),
+			BPF_LD_MAP_FD(BPF_REG_2, 0),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+				     BPF_FUNC_tail_call),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			/* if (sk) bpf_sk_release() */
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 1),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.fixup_prog1 = { 16 },
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "tail_call would lead to reference leak",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: leak checked reference over tail call",
+		.insns = {
+			BPF_MOV64_REG(BPF_REG_7, BPF_REG_1),
+			/* Look up socket and store in REG_6 */
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
+			/* if (!sk) goto end */
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 7),
+			/* bpf_tail_call() */
+			BPF_MOV64_IMM(BPF_REG_3, 0),
+			BPF_LD_MAP_FD(BPF_REG_2, 0),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+				     BPF_FUNC_tail_call),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.fixup_prog1 = { 17 },
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "tail_call would lead to reference leak",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: mangle and release sock_or_null",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, 5),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "R1 pointer arithmetic on sock_or_null prohibited",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: mangle and release sock",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, 5),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "R1 pointer arithmetic on sock prohibited",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: access member",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 3),
+			BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_0, 4),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.result = ACCEPT,
+	},
+	{
+		"reference tracking: write to member",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 5),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+			BPF_LD_IMM64(BPF_REG_2, 42),
+			BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_2,
+				    offsetof(struct bpf_sock, mark)),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_LD_IMM64(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "cannot write into socket",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: invalid 64-bit access of member",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 3),
+			BPF_LDX_MEM(BPF_DW, BPF_REG_2, BPF_REG_0, 0),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "invalid bpf_sock access off=0 size=8",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: access after release",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "!read_ok",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: direct access for lookup",
+		.insns = {
+			/* Check that the packet is at least 64B long */
+			BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+				    offsetof(struct __sk_buff, data)),
+			BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+				    offsetof(struct __sk_buff, data_end)),
+			BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 64),
+			BPF_JMP_REG(BPF_JGT, BPF_REG_0, BPF_REG_3, 9),
+			/* sk = sk_lookup_tcp(ctx, skb->data, ...) */
+			BPF_MOV64_IMM(BPF_REG_3, sizeof(struct bpf_sock_tuple)),
+			BPF_MOV64_IMM(BPF_REG_4, 0),
+			BPF_MOV64_IMM(BPF_REG_5, 0),
+			BPF_EMIT_CALL(BPF_FUNC_sk_lookup_tcp),
+			BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 3),
+			BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_0, 4),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.result = ACCEPT,
+	},
 };
 
 static int probe_filter_length(const struct bpf_insn *fp)
@@ -12652,18 +13411,18 @@ static int create_map(uint32_t type, uint32_t size_key,
 	return fd;
 }
 
-static int create_prog_dummy1(void)
+static int create_prog_dummy1(enum bpf_map_type prog_type)
 {
 	struct bpf_insn prog[] = {
 		BPF_MOV64_IMM(BPF_REG_0, 42),
 		BPF_EXIT_INSN(),
 	};
 
-	return bpf_load_program(BPF_PROG_TYPE_SOCKET_FILTER, prog,
+	return bpf_load_program(prog_type, prog,
 				ARRAY_SIZE(prog), "GPL", 0, NULL, 0);
 }
 
-static int create_prog_dummy2(int mfd, int idx)
+static int create_prog_dummy2(enum bpf_map_type prog_type, int mfd, int idx)
 {
 	struct bpf_insn prog[] = {
 		BPF_MOV64_IMM(BPF_REG_3, idx),
@@ -12674,11 +13433,12 @@ static int create_prog_dummy2(int mfd, int idx)
 		BPF_EXIT_INSN(),
 	};
 
-	return bpf_load_program(BPF_PROG_TYPE_SOCKET_FILTER, prog,
+	return bpf_load_program(prog_type, prog,
 				ARRAY_SIZE(prog), "GPL", 0, NULL, 0);
 }
 
-static int create_prog_array(uint32_t max_elem, int p1key)
+static int create_prog_array(enum bpf_map_type prog_type, uint32_t max_elem,
+			     int p1key)
 {
 	int p2key = 1;
 	int mfd, p1fd, p2fd;
@@ -12690,8 +13450,8 @@ static int create_prog_array(uint32_t max_elem, int p1key)
 		return -1;
 	}
 
-	p1fd = create_prog_dummy1();
-	p2fd = create_prog_dummy2(mfd, p2key);
+	p1fd = create_prog_dummy1(prog_type);
+	p2fd = create_prog_dummy2(prog_type, mfd, p2key);
 	if (p1fd < 0 || p2fd < 0)
 		goto out;
 	if (bpf_map_update_elem(mfd, &p1key, &p1fd, BPF_ANY) < 0)
@@ -12748,8 +13508,8 @@ static int create_cgroup_storage(bool percpu)
 
 static char bpf_vlog[UINT_MAX >> 8];
 
-static void do_test_fixup(struct bpf_test *test, struct bpf_insn *prog,
-			  int *map_fds)
+static void do_test_fixup(struct bpf_test *test, enum bpf_map_type prog_type,
+			  struct bpf_insn *prog, int *map_fds)
 {
 	int *fixup_map1 = test->fixup_map1;
 	int *fixup_map2 = test->fixup_map2;
@@ -12805,7 +13565,7 @@ static void do_test_fixup(struct bpf_test *test, struct bpf_insn *prog,
 	}
 
 	if (*fixup_prog1) {
-		map_fds[4] = create_prog_array(4, 0);
+		map_fds[4] = create_prog_array(prog_type, 4, 0);
 		do {
 			prog[*fixup_prog1].imm = map_fds[4];
 			fixup_prog1++;
@@ -12813,7 +13573,7 @@ static void do_test_fixup(struct bpf_test *test, struct bpf_insn *prog,
 	}
 
 	if (*fixup_prog2) {
-		map_fds[5] = create_prog_array(8, 7);
+		map_fds[5] = create_prog_array(prog_type, 8, 7);
 		do {
 			prog[*fixup_prog2].imm = map_fds[5];
 			fixup_prog2++;
@@ -12859,11 +13619,13 @@ static void do_test_single(struct bpf_test *test, bool unpriv,
 	for (i = 0; i < MAX_NR_MAPS; i++)
 		map_fds[i] = -1;
 
-	do_test_fixup(test, prog, map_fds);
+	if (!prog_type)
+		prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
+	do_test_fixup(test, prog_type, prog, map_fds);
 	prog_len = probe_filter_length(prog);
 
-	fd_prog = bpf_verify_program(prog_type ? : BPF_PROG_TYPE_SOCKET_FILTER,
-				     prog, prog_len, test->flags & F_LOAD_WITH_STRICT_ALIGNMENT,
+	fd_prog = bpf_verify_program(prog_type, prog, prog_len,
+				     test->flags & F_LOAD_WITH_STRICT_ALIGNMENT,
 				     "GPL", 0, bpf_vlog, sizeof(bpf_vlog), 1);
 
 	expected_ret = unpriv && test->result_unpriv != UNDEF ?