diff mbox series

[bpf-next,v2,1/2] bpf: allow sk_msg programs to read sock fields

Message ID 20180517211657.14426.15049.stgit@john-Precision-Tower-5810
State Accepted, archived
Delegated to: BPF Maintainers
Headers show
Series SK_MSG programs: read sock fields | expand

Commit Message

John Fastabend May 17, 2018, 9:16 p.m. UTC 
Currently sk_msg programs only have access to the raw data. However,
it is often useful when building policies to have the policies specific
to the socket endpoint. This allows using the socket tuple as input
into filters, etc.

This patch adds ctx access to the sock fields.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
---
 include/linux/filter.h   |    1 
 include/uapi/linux/bpf.h |    8 +++
 kernel/bpf/sockmap.c     |    1 
 net/core/filter.c        |  114 +++++++++++++++++++++++++++++++++++++++++++++-
 4 files changed, 121 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 9dbcb9d..d358d18 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 d94d333..97446bb 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 c6de139..0ebf157 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 6d0d156..aec5eba 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;