Merge branch 'bpf-event-output-helper-improvements'

Daniel Borkmann says:

====================
BPF event output helper improvements

This set adds improvements to the BPF event output helper to
support non-linear data sampling, here specifically, for skb
context. For details please see individual patches. The set
is based against net-next tree.

v1 -> v2:
  - Integrated and adapted Peter's diff into patch 1, updated
    the remaining ones accordingly. Thanks Peter!
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

arch/s390/kernel/perf_cpum_sf.c

@@ -979,12 +979,15 @@ static int perf_push_sample(struct perf_event *event, struct sf_raw_sample *sfr)
 	struct pt_regs regs;
 	struct perf_sf_sde_regs *sde_regs;
 	struct perf_sample_data data;
-	struct perf_raw_record raw;
+	struct perf_raw_record raw = {
+		.frag = {
+			.size = sfr->size,
+			.data = sfr,
+		},
+	};
 
 	/* Setup perf sample */
 	perf_sample_data_init(&data, 0, event->hw.last_period);
-	raw.size = sfr->size;
-	raw.data = sfr;
 	data.raw = &raw;
 
 	/* Setup pt_regs to look like an CPU-measurement external interrupt

arch/x86/events/amd/ibs.c

@@ -655,8 +655,12 @@ fail:
 	}
 
 	if (event->attr.sample_type & PERF_SAMPLE_RAW) {
-		raw.size = sizeof(u32) + ibs_data.size;
-		raw.data = ibs_data.data;
+		raw = (struct perf_raw_record){
+			.frag = {
+				.size = sizeof(u32) + ibs_data.size,
+				.data = ibs_data.data,
+			},
+		};
 		data.raw = &raw;
 	}
 

include/linux/bpf.h

@@ -209,7 +209,12 @@ u64 bpf_get_stackid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
 bool bpf_prog_array_compatible(struct bpf_array *array, const struct bpf_prog *fp);
 
 const struct bpf_func_proto *bpf_get_trace_printk_proto(void);
-const struct bpf_func_proto *bpf_get_event_output_proto(void);
+
+typedef unsigned long (*bpf_ctx_copy_t)(void *dst, const void *src,
+					unsigned long len);
+
+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);
 
 #ifdef CONFIG_BPF_SYSCALL
 DECLARE_PER_CPU(int, bpf_prog_active);

include/linux/perf_event.h

@@ -69,9 +69,22 @@ struct perf_callchain_entry_ctx {
 	bool			    contexts_maxed;
 };
 
+typedef unsigned long (*perf_copy_f)(void *dst, const void *src,
+				     unsigned long len);
+
+struct perf_raw_frag {
+	union {
+		struct perf_raw_frag	*next;
+		unsigned long		pad;
+	};
+	perf_copy_f			copy;
+	void				*data;
+	u32				size;
+} __packed;
+
 struct perf_raw_record {
+	struct perf_raw_frag		frag;
 	u32				size;
-	void				*data;
 };
 
 /*
@@ -1283,6 +1296,11 @@ extern void perf_restore_debug_store(void);
 static inline void perf_restore_debug_store(void)			{ }
 #endif
 
+static __always_inline bool perf_raw_frag_last(const struct perf_raw_frag *frag)
+{
+	return frag->pad < sizeof(u64);
+}
+
 #define perf_output_put(handle, x) perf_output_copy((handle), &(x), sizeof(x))
 
 /*

include/uapi/linux/bpf.h

@@ -401,6 +401,8 @@ enum bpf_func_id {
 /* BPF_FUNC_perf_event_output and BPF_FUNC_perf_event_read flags. */
 #define BPF_F_INDEX_MASK		0xffffffffULL
 #define BPF_F_CURRENT_CPU		BPF_F_INDEX_MASK
+/* BPF_FUNC_perf_event_output for sk_buff input context. */
+#define BPF_F_CTXLEN_MASK		(0xfffffULL << 32)
 
 /* user accessible mirror of in-kernel sk_buff.
  * new fields can only be added to the end of this structure

kernel/bpf/core.c

@@ -1054,9 +1054,11 @@ const struct bpf_func_proto * __weak bpf_get_trace_printk_proto(void)
 	return NULL;
 }
 
-const struct bpf_func_proto * __weak bpf_get_event_output_proto(void)
+u64 __weak
+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)
 {
-	return NULL;
+	return -ENOTSUPP;
 }
 
 /* Always built-in helper functions. */

kernel/events/core.c

@@ -5553,16 +5553,26 @@ void perf_output_sample(struct perf_output_handle *handle,
 	}
 
 	if (sample_type & PERF_SAMPLE_RAW) {
-		if (data->raw) {
-			u32 raw_size = data->raw->size;
-			u32 real_size = round_up(raw_size + sizeof(u32),
-						 sizeof(u64)) - sizeof(u32);
-			u64 zero = 0;
-
-			perf_output_put(handle, real_size);
-			__output_copy(handle, data->raw->data, raw_size);
-			if (real_size - raw_size)
-				__output_copy(handle, &zero, real_size - raw_size);
+		struct perf_raw_record *raw = data->raw;
+
+		if (raw) {
+			struct perf_raw_frag *frag = &raw->frag;
+
+			perf_output_put(handle, raw->size);
+			do {
+				if (frag->copy) {
+					__output_custom(handle, frag->copy,
+							frag->data, frag->size);
+				} else {
+					__output_copy(handle, frag->data,
+						      frag->size);
+				}
+				if (perf_raw_frag_last(frag))
+					break;
+				frag = frag->next;
+			} while (1);
+			if (frag->pad)
+				__output_skip(handle, NULL, frag->pad);
 		} else {
 			struct {
 				u32	size;
@@ -5687,14 +5697,28 @@ void perf_prepare_sample(struct perf_event_header *header,
 	}
 
 	if (sample_type & PERF_SAMPLE_RAW) {
-		int size = sizeof(u32);
-
-		if (data->raw)
-			size += data->raw->size;
-		else
-			size += sizeof(u32);
+		struct perf_raw_record *raw = data->raw;
+		int size;
+
+		if (raw) {
+			struct perf_raw_frag *frag = &raw->frag;
+			u32 sum = 0;
+
+			do {
+				sum += frag->size;
+				if (perf_raw_frag_last(frag))
+					break;
+				frag = frag->next;
+			} while (1);
+
+			size = round_up(sum + sizeof(u32), sizeof(u64));
+			raw->size = size - sizeof(u32);
+			frag->pad = raw->size - sum;
+		} else {
+			size = sizeof(u64);
+		}
 
-		header->size += round_up(size, sizeof(u64));
+		header->size += size;
 	}
 
 	if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
@@ -7331,7 +7355,7 @@ static struct pmu perf_swevent = {
 static int perf_tp_filter_match(struct perf_event *event,
 				struct perf_sample_data *data)
 {
-	void *record = data->raw->data;
+	void *record = data->raw->frag.data;
 
 	/* only top level events have filters set */
 	if (event->parent)
@@ -7387,8 +7411,10 @@ void perf_tp_event(u16 event_type, u64 count, void *record, int entry_size,
 	struct perf_event *event;
 
 	struct perf_raw_record raw = {
-		.size = entry_size,
-		.data = record,
+		.frag = {
+			.size = entry_size,
+			.data = record,
+		},
 	};
 
 	perf_sample_data_init(&data, 0, 0);

kernel/events/internal.h

@@ -123,10 +123,7 @@ static inline unsigned long perf_aux_size(struct ring_buffer *rb)
 	return rb->aux_nr_pages << PAGE_SHIFT;
 }
 
-#define DEFINE_OUTPUT_COPY(func_name, memcpy_func)			\
-static inline unsigned long						\
-func_name(struct perf_output_handle *handle,				\
-	  const void *buf, unsigned long len)				\
+#define __DEFINE_OUTPUT_COPY_BODY(memcpy_func)				\
 {									\
 	unsigned long size, written;					\
 									\
@@ -152,6 +149,17 @@ func_name(struct perf_output_handle *handle,				\
 	return len;							\
 }
 
+#define DEFINE_OUTPUT_COPY(func_name, memcpy_func)			\
+static inline unsigned long						\
+func_name(struct perf_output_handle *handle,				\
+	  const void *buf, unsigned long len)				\
+__DEFINE_OUTPUT_COPY_BODY(memcpy_func)
+
+static inline unsigned long
+__output_custom(struct perf_output_handle *handle, perf_copy_f copy_func,
+		const void *buf, unsigned long len)
+__DEFINE_OUTPUT_COPY_BODY(copy_func)
+
 static inline unsigned long
 memcpy_common(void *dst, const void *src, unsigned long n)
 {

kernel/trace/bpf_trace.c

@@ -233,24 +233,17 @@ static const struct bpf_func_proto bpf_perf_event_read_proto = {
 	.arg2_type	= ARG_ANYTHING,
 };
 
-static u64 bpf_perf_event_output(u64 r1, u64 r2, u64 flags, u64 r4, u64 size)
+static __always_inline u64
+__bpf_perf_event_output(struct pt_regs *regs, struct bpf_map *map,
+			u64 flags, struct perf_raw_record *raw)
 {
-	struct pt_regs *regs = (struct pt_regs *) (long) r1;
-	struct bpf_map *map = (struct bpf_map *) (long) r2;
 	struct bpf_array *array = container_of(map, struct bpf_array, map);
 	unsigned int cpu = smp_processor_id();
 	u64 index = flags & BPF_F_INDEX_MASK;
-	void *data = (void *) (long) r4;
 	struct perf_sample_data sample_data;
 	struct bpf_event_entry *ee;
 	struct perf_event *event;
-	struct perf_raw_record raw = {
-		.size = size,
-		.data = data,
-	};
 
-	if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
-		return -EINVAL;
 	if (index == BPF_F_CURRENT_CPU)
 		index = cpu;
 	if (unlikely(index >= array->map.max_entries))
@@ -269,11 +262,29 @@ static u64 bpf_perf_event_output(u64 r1, u64 r2, u64 flags, u64 r4, u64 size)
 		return -EOPNOTSUPP;
 
 	perf_sample_data_init(&sample_data, 0, 0);
-	sample_data.raw = &raw;
+	sample_data.raw = raw;
 	perf_event_output(event, &sample_data, regs);
 	return 0;
 }
 
+static u64 bpf_perf_event_output(u64 r1, u64 r2, u64 flags, u64 r4, u64 size)
+{
+	struct pt_regs *regs = (struct pt_regs *)(long) r1;
+	struct bpf_map *map  = (struct bpf_map *)(long) r2;
+	void *data = (void *)(long) r4;
+	struct perf_raw_record raw = {
+		.frag = {
+			.size = size,
+			.data = data,
+		},
+	};
+
+	if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
+		return -EINVAL;
+
+	return __bpf_perf_event_output(regs, map, flags, &raw);
+}
+
 static const struct bpf_func_proto bpf_perf_event_output_proto = {
 	.func		= bpf_perf_event_output,
 	.gpl_only	= true,
@@ -287,29 +298,26 @@ static const struct bpf_func_proto bpf_perf_event_output_proto = {
 
 static DEFINE_PER_CPU(struct pt_regs, bpf_pt_regs);
 
-static u64 bpf_event_output(u64 r1, u64 r2, u64 flags, u64 r4, u64 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)
 {
 	struct pt_regs *regs = this_cpu_ptr(&bpf_pt_regs);
+	struct perf_raw_frag frag = {
+		.copy		= ctx_copy,
+		.size		= ctx_size,
+		.data		= ctx,
+	};
+	struct perf_raw_record raw = {
+		.frag = {
+			.next	= ctx_size ? &frag : NULL,
+			.size	= meta_size,
+			.data	= meta,
+		},
+	};
 
 	perf_fetch_caller_regs(regs);
 
-	return bpf_perf_event_output((long)regs, r2, flags, r4, size);
-}
-
-static const struct bpf_func_proto bpf_event_output_proto = {
-	.func		= bpf_event_output,
-	.gpl_only	= true,
-	.ret_type	= RET_INTEGER,
-	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_CONST_MAP_PTR,
-	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_STACK,
-	.arg5_type	= ARG_CONST_STACK_SIZE,
-};
-
-const struct bpf_func_proto *bpf_get_event_output_proto(void)
-{
-	return &bpf_event_output_proto;
+	return __bpf_perf_event_output(regs, map, flags, &raw);
 }
 
 static u64 bpf_get_current_task(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)

net/core/filter.c

@@ -2025,6 +2025,47 @@ bool bpf_helper_changes_skb_data(void *func)
 	return false;
 }
 
+static unsigned long bpf_skb_copy(void *dst_buff, const void *skb,
+				  unsigned long len)
+{
+	void *ptr = skb_header_pointer(skb, 0, len, dst_buff);
+
+	if (unlikely(!ptr))
+		return len;
+	if (ptr != dst_buff)
+		memcpy(dst_buff, ptr, len);
+
+	return 0;
+}
+
+static u64 bpf_skb_event_output(u64 r1, u64 r2, u64 flags, u64 r4,
+				u64 meta_size)
+{
+	struct sk_buff *skb = (struct sk_buff *)(long) r1;
+	struct bpf_map *map = (struct bpf_map *)(long) r2;
+	u64 skb_size = (flags & BPF_F_CTXLEN_MASK) >> 32;
+	void *meta = (void *)(long) r4;
+
+	if (unlikely(flags & ~(BPF_F_CTXLEN_MASK | BPF_F_INDEX_MASK)))
+		return -EINVAL;
+	if (unlikely(skb_size > skb->len))
+		return -EFAULT;
+
+	return bpf_event_output(map, flags, meta, meta_size, skb, skb_size,
+				bpf_skb_copy);
+}
+
+static const struct bpf_func_proto bpf_skb_event_output_proto = {
+	.func		= bpf_skb_event_output,
+	.gpl_only	= true,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_CTX,
+	.arg2_type	= ARG_CONST_MAP_PTR,
+	.arg3_type	= ARG_ANYTHING,
+	.arg4_type	= ARG_PTR_TO_STACK,
+	.arg5_type	= ARG_CONST_STACK_SIZE,
+};
+
 static unsigned short bpf_tunnel_key_af(u64 flags)
 {
 	return flags & BPF_F_TUNINFO_IPV6 ? AF_INET6 : AF_INET;
@@ -2357,7 +2398,7 @@ tc_cls_act_func_proto(enum bpf_func_id func_id)
 	case BPF_FUNC_get_hash_recalc:
 		return &bpf_get_hash_recalc_proto;
 	case BPF_FUNC_perf_event_output:
-		return bpf_get_event_output_proto();
+		return &bpf_skb_event_output_proto;
 	case BPF_FUNC_get_smp_processor_id:
 		return &bpf_get_smp_processor_id_proto;
 #ifdef CONFIG_SOCK_CGROUP_DATA