samples/bpf: add verifier tests for the helper access to the packet

test various corner cases of the helper function access to the packet
via crafted XDP programs.

Signed-off-by: Aaron Yue <haoxuany@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

samples/bpf/test_verifier.c

@@ -1449,7 +1449,7 @@ static struct bpf_test tests[] = {
 		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
 	},
 	{
-		"pkt: test1",
+		"direct packet access: test1",
 		.insns = {
 			BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
 				    offsetof(struct __sk_buff, data)),
@@ -1466,7 +1466,7 @@ static struct bpf_test tests[] = {
 		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
 	},
 	{
-		"pkt: test2",
+		"direct packet access: test2",
 		.insns = {
 			BPF_MOV64_IMM(BPF_REG_0, 1),
 			BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_1,
@@ -1499,7 +1499,7 @@ static struct bpf_test tests[] = {
 		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
 	},
 	{
-		"pkt: test3",
+		"direct packet access: test3",
 		.insns = {
 			BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
 				    offsetof(struct __sk_buff, data)),
@@ -1511,7 +1511,7 @@ static struct bpf_test tests[] = {
 		.prog_type = BPF_PROG_TYPE_SOCKET_FILTER,
 	},
 	{
-		"pkt: test4",
+		"direct packet access: test4",
 		.insns = {
 			BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
 				    offsetof(struct __sk_buff, data)),
@@ -1528,6 +1528,112 @@ static struct bpf_test tests[] = {
 		.result = REJECT,
 		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
 	},
+	{
+		"helper access to packet: test1, valid packet_ptr range",
+		.insns = {
+			BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+				    offsetof(struct xdp_md, data)),
+			BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+				    offsetof(struct xdp_md, data_end)),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_2),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, 8),
+			BPF_JMP_REG(BPF_JGT, BPF_REG_1, BPF_REG_3, 5),
+			BPF_LD_MAP_FD(BPF_REG_1, 0),
+			BPF_MOV64_REG(BPF_REG_3, BPF_REG_2),
+			BPF_MOV64_IMM(BPF_REG_4, 0),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_update_elem),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+		},
+		.fixup = {5},
+		.result_unpriv = ACCEPT,
+		.result = ACCEPT,
+		.prog_type = BPF_PROG_TYPE_XDP,
+	},
+	{
+		"helper access to packet: test2, unchecked packet_ptr",
+		.insns = {
+			BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+				    offsetof(struct xdp_md, data)),
+			BPF_LD_MAP_FD(BPF_REG_1, 0),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+		},
+		.fixup = {1},
+		.result = REJECT,
+		.errstr = "invalid access to packet",
+		.prog_type = BPF_PROG_TYPE_XDP,
+	},
+	{
+		"helper access to packet: test3, variable add",
+		.insns = {
+			BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+					offsetof(struct xdp_md, data)),
+			BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+					offsetof(struct xdp_md, data_end)),
+			BPF_MOV64_REG(BPF_REG_4, BPF_REG_2),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, 8),
+			BPF_JMP_REG(BPF_JGT, BPF_REG_4, BPF_REG_3, 10),
+			BPF_LDX_MEM(BPF_B, BPF_REG_5, BPF_REG_2, 0),
+			BPF_MOV64_REG(BPF_REG_4, BPF_REG_2),
+			BPF_ALU64_REG(BPF_ADD, BPF_REG_4, BPF_REG_5),
+			BPF_MOV64_REG(BPF_REG_5, BPF_REG_4),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_5, 8),
+			BPF_JMP_REG(BPF_JGT, BPF_REG_5, BPF_REG_3, 4),
+			BPF_LD_MAP_FD(BPF_REG_1, 0),
+			BPF_MOV64_REG(BPF_REG_2, BPF_REG_4),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+		},
+		.fixup = {11},
+		.result = ACCEPT,
+		.prog_type = BPF_PROG_TYPE_XDP,
+	},
+	{
+		"helper access to packet: test4, packet_ptr with bad range",
+		.insns = {
+			BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+				    offsetof(struct xdp_md, data)),
+			BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+				    offsetof(struct xdp_md, data_end)),
+			BPF_MOV64_REG(BPF_REG_4, BPF_REG_2),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, 4),
+			BPF_JMP_REG(BPF_JGT, BPF_REG_4, BPF_REG_3, 2),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+			BPF_LD_MAP_FD(BPF_REG_1, 0),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+		},
+		.fixup = {7},
+		.result = REJECT,
+		.errstr = "invalid access to packet",
+		.prog_type = BPF_PROG_TYPE_XDP,
+	},
+	{
+		"helper access to packet: test5, packet_ptr with too short range",
+		.insns = {
+			BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+				    offsetof(struct xdp_md, data)),
+			BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+				    offsetof(struct xdp_md, data_end)),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, 1),
+			BPF_MOV64_REG(BPF_REG_4, BPF_REG_2),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, 7),
+			BPF_JMP_REG(BPF_JGT, BPF_REG_4, BPF_REG_3, 3),
+			BPF_LD_MAP_FD(BPF_REG_1, 0),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+		},
+		.fixup = {6},
+		.result = REJECT,
+		.errstr = "invalid access to packet",
+		.prog_type = BPF_PROG_TYPE_XDP,
+	},
 };
 
 static int probe_filter_length(struct bpf_insn *fp)