Merge branch 'bpf-sk-msg-fields'

John Fastabend says:

====================
In this series we add the ability for sk msg programs to read basic
sock information about the sock they are attached to. The second
patch adds the tests to the selftest test_verifier.

One observation that I had from writing this seriess is lots of the
./net/core/filter.c code is almost duplicated across program types.
I thought about building a template/macro that we could use as a
single block of code to read sock data out for multiple programs,
but I wasn't convinced it was worth it yet. The result was using a
macro saved a couple lines of code per block but made the code
a bit harder to read IMO. We can probably revisit the idea later
if we get more duplication.

v2: add errstr field to negative test_verifier test cases to ensure
    we get the expected err string back from the verifier.
====================

Signed-off-by: Daniel Borkmann <[email protected]>

6 files changed, 244 insertions, 3 deletions

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 9dbcb9d55921..d358d1815c16 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -517,6 +517,7 @@ struct sk_msg_buff {
 	bool sg_copy[MAX_SKB_FRAGS];
 	__u32 flags;
 	struct sock *sk_redir;
+	struct sock *sk;
 	struct sk_buff *skb;
 	struct list_head list;
 };
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index d94d333a8225..97446bbe2ca5 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -2176,6 +2176,14 @@ enum sk_action {
 struct sk_msg_md {
 	void *data;
 	void *data_end;
+
+	__u32 family;
+	__u32 remote_ip4;	/* Stored in network byte order */
+	__u32 local_ip4;	/* Stored in network byte order */
+	__u32 remote_ip6[4];	/* Stored in network byte order */
+	__u32 local_ip6[4];	/* Stored in network byte order */
+	__u32 remote_port;	/* Stored in network byte order */
+	__u32 local_port;	/* stored in host byte order */
 };
 
 #define BPF_TAG_SIZE	8
diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c
index c682669570dc..3b28955a6383 100644
--- a/kernel/bpf/sockmap.c
+++ b/kernel/bpf/sockmap.c
@@ -523,6 +523,7 @@ static unsigned int smap_do_tx_msg(struct sock *sk,
 	}
 
 	bpf_compute_data_pointers_sg(md);
+	md->sk = sk;
 	rc = (*prog->bpf_func)(md, prog->insnsi);
 	psock->apply_bytes = md->apply_bytes;
 
diff --git a/net/core/filter.c b/net/core/filter.c
index 6d0d1560bd70..aec5ebafb262 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5148,18 +5148,23 @@ static bool sk_msg_is_valid_access(int off, int size,
 	switch (off) {
 	case offsetof(struct sk_msg_md, data):
 		info->reg_type = PTR_TO_PACKET;
+		if (size != sizeof(__u64))
+			return false;
 		break;
 	case offsetof(struct sk_msg_md, data_end):
 		info->reg_type = PTR_TO_PACKET_END;
+		if (size != sizeof(__u64))
+			return false;
 		break;
+	default:
+		if (size != sizeof(__u32))
+			return false;
 	}
 
 	if (off < 0 || off >= sizeof(struct sk_msg_md))
 		return false;
 	if (off % size != 0)
 		return false;
-	if (size != sizeof(__u64))
-		return false;
 
 	return true;
 }
@@ -5835,7 +5840,8 @@ static u32 sock_ops_convert_ctx_access(enum bpf_access_type type,
 		break;
 
 	case offsetof(struct bpf_sock_ops, local_ip4):
-		BUILD_BUG_ON(FIELD_SIZEOF(struct sock_common, skc_rcv_saddr) != 4);
+		BUILD_BUG_ON(FIELD_SIZEOF(struct sock_common,
+					  skc_rcv_saddr) != 4);
 
 		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(
 					      struct bpf_sock_ops_kern, sk),
@@ -6152,6 +6158,7 @@ static u32 sk_msg_convert_ctx_access(enum bpf_access_type type,
 				     struct bpf_prog *prog, u32 *target_size)
 {
 	struct bpf_insn *insn = insn_buf;
+	int off;
 
 	switch (si->off) {
 	case offsetof(struct sk_msg_md, data):
@@ -6164,6 +6171,107 @@ static u32 sk_msg_convert_ctx_access(enum bpf_access_type type,
 				      si->dst_reg, si->src_reg,
 				      offsetof(struct sk_msg_buff, data_end));
 		break;
+	case offsetof(struct sk_msg_md, family):
+		BUILD_BUG_ON(FIELD_SIZEOF(struct sock_common, skc_family) != 2);
+
+		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(
+					      struct sk_msg_buff, sk),
+				      si->dst_reg, si->src_reg,
+				      offsetof(struct sk_msg_buff, sk));
+		*insn++ = BPF_LDX_MEM(BPF_H, si->dst_reg, si->dst_reg,
+				      offsetof(struct sock_common, skc_family));
+		break;
+
+	case offsetof(struct sk_msg_md, remote_ip4):
+		BUILD_BUG_ON(FIELD_SIZEOF(struct sock_common, skc_daddr) != 4);
+
+		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(
+						struct sk_msg_buff, sk),
+				      si->dst_reg, si->src_reg,
+				      offsetof(struct sk_msg_buff, sk));
+		*insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->dst_reg,
+				      offsetof(struct sock_common, skc_daddr));
+		break;
+
+	case offsetof(struct sk_msg_md, local_ip4):
+		BUILD_BUG_ON(FIELD_SIZEOF(struct sock_common,
+					  skc_rcv_saddr) != 4);
+
+		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(
+					      struct sk_msg_buff, sk),
+				      si->dst_reg, si->src_reg,
+				      offsetof(struct sk_msg_buff, sk));
+		*insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->dst_reg,
+				      offsetof(struct sock_common,
+					       skc_rcv_saddr));
+		break;
+
+	case offsetof(struct sk_msg_md, remote_ip6[0]) ...
+	     offsetof(struct sk_msg_md, remote_ip6[3]):
+#if IS_ENABLED(CONFIG_IPV6)
+		BUILD_BUG_ON(FIELD_SIZEOF(struct sock_common,
+					  skc_v6_daddr.s6_addr32[0]) != 4);
+
+		off = si->off;
+		off -= offsetof(struct sk_msg_md, remote_ip6[0]);
+		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(
+						struct sk_msg_buff, sk),
+				      si->dst_reg, si->src_reg,
+				      offsetof(struct sk_msg_buff, sk));
+		*insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->dst_reg,
+				      offsetof(struct sock_common,
+					       skc_v6_daddr.s6_addr32[0]) +
+				      off);
+#else
+		*insn++ = BPF_MOV32_IMM(si->dst_reg, 0);
+#endif
+		break;
+
+	case offsetof(struct sk_msg_md, local_ip6[0]) ...
+	     offsetof(struct sk_msg_md, local_ip6[3]):
+#if IS_ENABLED(CONFIG_IPV6)
+		BUILD_BUG_ON(FIELD_SIZEOF(struct sock_common,
+					  skc_v6_rcv_saddr.s6_addr32[0]) != 4);
+
+		off = si->off;
+		off -= offsetof(struct sk_msg_md, local_ip6[0]);
+		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(
+						struct sk_msg_buff, sk),
+				      si->dst_reg, si->src_reg,
+				      offsetof(struct sk_msg_buff, sk));
+		*insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->dst_reg,
+				      offsetof(struct sock_common,
+					       skc_v6_rcv_saddr.s6_addr32[0]) +
+				      off);
+#else
+		*insn++ = BPF_MOV32_IMM(si->dst_reg, 0);
+#endif
+		break;
+
+	case offsetof(struct sk_msg_md, remote_port):
+		BUILD_BUG_ON(FIELD_SIZEOF(struct sock_common, skc_dport) != 2);
+
+		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(
+						struct sk_msg_buff, sk),
+				      si->dst_reg, si->src_reg,
+				      offsetof(struct sk_msg_buff, sk));
+		*insn++ = BPF_LDX_MEM(BPF_H, si->dst_reg, si->dst_reg,
+				      offsetof(struct sock_common, skc_dport));
+#ifndef __BIG_ENDIAN_BITFIELD
+		*insn++ = BPF_ALU32_IMM(BPF_LSH, si->dst_reg, 16);
+#endif
+		break;
+
+	case offsetof(struct sk_msg_md, local_port):
+		BUILD_BUG_ON(FIELD_SIZEOF(struct sock_common, skc_num) != 2);
+
+		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(
+						struct sk_msg_buff, sk),
+				      si->dst_reg, si->src_reg,
+				      offsetof(struct sk_msg_buff, sk));
+		*insn++ = BPF_LDX_MEM(BPF_H, si->dst_reg, si->dst_reg,
+				      offsetof(struct sock_common, skc_num));
+		break;
 	}
 
 	return insn - insn_buf;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index d94d333a8225..97446bbe2ca5 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -2176,6 +2176,14 @@ enum sk_action {
 struct sk_msg_md {
 	void *data;
 	void *data_end;
+
+	__u32 family;
+	__u32 remote_ip4;	/* Stored in network byte order */
+	__u32 local_ip4;	/* Stored in network byte order */
+	__u32 remote_ip6[4];	/* Stored in network byte order */
+	__u32 local_ip6[4];	/* Stored in network byte order */
+	__u32 remote_port;	/* Stored in network byte order */
+	__u32 local_port;	/* stored in host byte order */
 };
 
 #define BPF_TAG_SIZE	8
diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index a877af00605d..6ec4d9def877 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -1686,6 +1686,121 @@ static struct bpf_test tests[] = {
 		.prog_type = BPF_PROG_TYPE_SK_SKB,
 	},
 	{
+		"valid access family in SK_MSG",
+		.insns = {
+			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+				    offsetof(struct sk_msg_md, family)),
+			BPF_EXIT_INSN(),
+		},
+		.result = ACCEPT,
+		.prog_type = BPF_PROG_TYPE_SK_MSG,
+	},
+	{
+		"valid access remote_ip4 in SK_MSG",
+		.insns = {
+			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+				    offsetof(struct sk_msg_md, remote_ip4)),
+			BPF_EXIT_INSN(),
+		},
+		.result = ACCEPT,
+		.prog_type = BPF_PROG_TYPE_SK_MSG,
+	},
+	{
+		"valid access local_ip4 in SK_MSG",
+		.insns = {
+			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+				    offsetof(struct sk_msg_md, local_ip4)),
+			BPF_EXIT_INSN(),
+		},
+		.result = ACCEPT,
+		.prog_type = BPF_PROG_TYPE_SK_MSG,
+	},
+	{
+		"valid access remote_port in SK_MSG",
+		.insns = {
+			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+				    offsetof(struct sk_msg_md, remote_port)),
+			BPF_EXIT_INSN(),
+		},
+		.result = ACCEPT,
+		.prog_type = BPF_PROG_TYPE_SK_MSG,
+	},
+	{
+		"valid access local_port in SK_MSG",
+		.insns = {
+			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+				    offsetof(struct sk_msg_md, local_port)),
+			BPF_EXIT_INSN(),
+		},
+		.result = ACCEPT,
+		.prog_type = BPF_PROG_TYPE_SK_MSG,
+	},
+	{
+		"valid access remote_ip6 in SK_MSG",
+		.insns = {
+			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+				    offsetof(struct sk_msg_md, remote_ip6[0])),
+			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+				    offsetof(struct sk_msg_md, remote_ip6[1])),
+			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+				    offsetof(struct sk_msg_md, remote_ip6[2])),
+			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+				    offsetof(struct sk_msg_md, remote_ip6[3])),
+			BPF_EXIT_INSN(),
+		},
+		.result = ACCEPT,
+		.prog_type = BPF_PROG_TYPE_SK_SKB,
+	},
+	{
+		"valid access local_ip6 in SK_MSG",
+		.insns = {
+			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+				    offsetof(struct sk_msg_md, local_ip6[0])),
+			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+				    offsetof(struct sk_msg_md, local_ip6[1])),
+			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+				    offsetof(struct sk_msg_md, local_ip6[2])),
+			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+				    offsetof(struct sk_msg_md, local_ip6[3])),
+			BPF_EXIT_INSN(),
+		},
+		.result = ACCEPT,
+		.prog_type = BPF_PROG_TYPE_SK_SKB,
+	},
+	{
+		"invalid 64B read of family in SK_MSG",
+		.insns = {
+			BPF_LDX_MEM(BPF_DW, BPF_REG_2, BPF_REG_1,
+				    offsetof(struct sk_msg_md, family)),
+			BPF_EXIT_INSN(),
+		},
+		.errstr = "invalid bpf_context access",
+		.result = REJECT,
+		.prog_type = BPF_PROG_TYPE_SK_MSG,
+	},
+	{
+		"invalid read past end of SK_MSG",
+		.insns = {
+			BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+				    offsetof(struct sk_msg_md, local_port) + 4),
+			BPF_EXIT_INSN(),
+		},
+		.errstr = "R0 !read_ok",
+		.result = REJECT,
+		.prog_type = BPF_PROG_TYPE_SK_MSG,
+	},
+	{
+		"invalid read offset in SK_MSG",
+		.insns = {
+			BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+				    offsetof(struct sk_msg_md, family) + 1),
+			BPF_EXIT_INSN(),
+		},
+		.errstr = "invalid bpf_context access",
+		.result = REJECT,
+		.prog_type = BPF_PROG_TYPE_SK_MSG,
+	},
+	{
 		"direct packet read for SK_MSG",
 		.insns = {
 			BPF_LDX_MEM(BPF_DW, BPF_REG_2, BPF_REG_1,