[PATCH v2 bpf-next 0/5] bpf: Hooks for sys_sendmsg

[PATCH v2 bpf-next 0/5] bpf: Hooks for sys_sendmsg

[Andrey Ignatov]

v1 -> v2:
* return ENOTSUPP if bpf_prog rewrote IPv6-only with IPv4-mapped IPv6;
* add test for IPv4-mapped IPv6 use-case;
* fix build for CONFIG_CGROUP_BPF=n;
* rebase.

This path set adds BPF hooks for sys_sendmsg similar to existing hooks for
sys_bind and sys_connect.

Hooks allow to override source IP (including the case when it's set via
cmsg(3)) and destination IP:port for unconnected UDP (slow path). TCP and
connected UDP (fast path) are not affected. This makes UDP support
complete: connected UDP is handled by sys_connect hooks, unconnected by
sys_sendmsg ones.

Similar to sys_connect hooks, sys_sendmsg ones can be used to make system
calls such as sendmsg(2) and sendto(2) return EPERM.

Please see patch 0001 for more details.

Andrey Ignatov (5):
  bpf: Hooks for sys_sendmsg
  bpf: Sync bpf.h to tools/
  libbpf: Support guessing sendmsg{4,6} progs
  selftests/bpf: Prepare test_sock_addr for extension
  selftests/bpf: Selftest for sys_sendmsg hooks

 include/linux/bpf-cgroup.h                   |   23 +-
 include/linux/filter.h                       |    1 +
 include/uapi/linux/bpf.h                     |    8 +
 kernel/bpf/cgroup.c                          |   11 +-
 kernel/bpf/syscall.c                         |    8 +
 net/core/filter.c                            |   39 +
 net/ipv4/udp.c                               |   20 +-
 net/ipv6/udp.c                               |   24 +
 tools/include/uapi/linux/bpf.h               |    8 +
 tools/lib/bpf/libbpf.c                       |    2 +
 tools/testing/selftests/bpf/Makefile         |    3 +-
 tools/testing/selftests/bpf/sendmsg4_prog.c  |   49 ++
 tools/testing/selftests/bpf/sendmsg6_prog.c  |   60 ++
 tools/testing/selftests/bpf/test_sock_addr.c | 1155 +++++++++++++++++++++-----
 14 files changed, 1215 insertions(+), 196 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/sendmsg4_prog.c
 create mode 100644 tools/testing/selftests/bpf/sendmsg6_prog.c

-- 
2.9.5

[PATCH v2 bpf-next 1/5] bpf: Hooks for sys_sendmsg

[Andrey Ignatov]

In addition to already existing BPF hooks for sys_bind and sys_connect,
the patch provides new hooks for sys_sendmsg.

It leverages existing BPF program type `BPF_PROG_TYPE_CGROUP_SOCK_ADDR`
that provides access to socket itlself (properties like family, type,
protocol) and user-passed `struct sockaddr *` so that BPF program can
override destination IP and port for system calls such as sendto(2) or
sendmsg(2) and/or assign source IP to the socket.

The hooks are implemented as two new attach types:
`BPF_CGROUP_UDP4_SENDMSG` and `BPF_CGROUP_UDP6_SENDMSG` for UDPv4 and
UDPv6 correspondingly.

UDPv4 and UDPv6 separate attach types for same reason as sys_bind and
sys_connect hooks, i.e. to prevent reading from / writing to e.g.
user_ip6 fields when user passes sockaddr_in since it'd be out-of-bound.

The difference with already existing hooks is sys_sendmsg are
implemented only for unconnected UDP.

For TCP it doesn't make sense to change user-provided `struct sockaddr *`
at sendto(2)/sendmsg(2) time since socket either was already connected
and has source/destination set or wasn't connected and call to
sendto(2)/sendmsg(2) would lead to ENOTCONN anyway.

Connected UDP is already handled by sys_connect hooks that can override
source/destination at connect time and use fast-path later, i.e. these
hooks don't affect UDP fast-path.

Rewriting source IP is implemented differently than that in sys_connect
hooks. When sys_sendmsg is used with unconnected UDP it doesn't work to
just bind socket to desired local IP address since source IP can be set
on per-packet basis by using ancillary data (cmsg(3)). So no matter if
socket is bound or not, source IP has to be rewritten on every call to
sys_sendmsg.

To do so two new fields are added to UAPI `struct bpf_sock_addr`;
* `msg_src_ip4` to set source IPv4 for UDPv4;
* `msg_src_ip6` to set source IPv6 for UDPv6.

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
---
 include/linux/bpf-cgroup.h | 23 +++++++++++++++++------
 include/linux/filter.h     |  1 +
 include/uapi/linux/bpf.h   |  8 ++++++++
 kernel/bpf/cgroup.c        | 11 ++++++++++-
 kernel/bpf/syscall.c       |  8 ++++++++
 net/core/filter.c          | 39 +++++++++++++++++++++++++++++++++++++++
 net/ipv4/udp.c             | 20 ++++++++++++++++++--
 net/ipv6/udp.c             | 24 ++++++++++++++++++++++++
 8 files changed, 125 insertions(+), 9 deletions(-)

diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index 30d15e6..29f8085 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -66,7 +66,8 @@ int __cgroup_bpf_run_filter_sk(struct sock *sk,
 
 int __cgroup_bpf_run_filter_sock_addr(struct sock *sk,
 				      struct sockaddr *uaddr,
-				      enum bpf_attach_type type);
+				      enum bpf_attach_type type,
+				      void *t_ctx);
 
 int __cgroup_bpf_run_filter_sock_ops(struct sock *sk,
 				     struct bpf_sock_ops_kern *sock_ops,
@@ -120,16 +121,18 @@ int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor,
 ({									       \
 	int __ret = 0;							       \
 	if (cgroup_bpf_enabled)						       \
-		__ret = __cgroup_bpf_run_filter_sock_addr(sk, uaddr, type);    \
+		__ret = __cgroup_bpf_run_filter_sock_addr(sk, uaddr, type,     \
+							  NULL);	       \
 	__ret;								       \
 })
 
-#define BPF_CGROUP_RUN_SA_PROG_LOCK(sk, uaddr, type)			       \
+#define BPF_CGROUP_RUN_SA_PROG_LOCK(sk, uaddr, type, t_ctx)		       \
 ({									       \
 	int __ret = 0;							       \
 	if (cgroup_bpf_enabled)	{					       \
 		lock_sock(sk);						       \
-		__ret = __cgroup_bpf_run_filter_sock_addr(sk, uaddr, type);    \
+		__ret = __cgroup_bpf_run_filter_sock_addr(sk, uaddr, type,     \
+							  t_ctx);	       \
 		release_sock(sk);					       \
 	}								       \
 	__ret;								       \
@@ -151,10 +154,16 @@ int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor,
 	BPF_CGROUP_RUN_SA_PROG(sk, uaddr, BPF_CGROUP_INET6_CONNECT)
 
 #define BPF_CGROUP_RUN_PROG_INET4_CONNECT_LOCK(sk, uaddr)		       \
-	BPF_CGROUP_RUN_SA_PROG_LOCK(sk, uaddr, BPF_CGROUP_INET4_CONNECT)
+	BPF_CGROUP_RUN_SA_PROG_LOCK(sk, uaddr, BPF_CGROUP_INET4_CONNECT, NULL)
 
 #define BPF_CGROUP_RUN_PROG_INET6_CONNECT_LOCK(sk, uaddr)		       \
-	BPF_CGROUP_RUN_SA_PROG_LOCK(sk, uaddr, BPF_CGROUP_INET6_CONNECT)
+	BPF_CGROUP_RUN_SA_PROG_LOCK(sk, uaddr, BPF_CGROUP_INET6_CONNECT, NULL)
+
+#define BPF_CGROUP_RUN_PROG_UDP4_SENDMSG_LOCK(sk, uaddr, t_ctx)		       \
+	BPF_CGROUP_RUN_SA_PROG_LOCK(sk, uaddr, BPF_CGROUP_UDP4_SENDMSG, t_ctx)
+
+#define BPF_CGROUP_RUN_PROG_UDP6_SENDMSG_LOCK(sk, uaddr, t_ctx)		       \
+	BPF_CGROUP_RUN_SA_PROG_LOCK(sk, uaddr, BPF_CGROUP_UDP6_SENDMSG, t_ctx)
 
 #define BPF_CGROUP_RUN_PROG_SOCK_OPS(sock_ops)				       \
 ({									       \
@@ -197,6 +206,8 @@ static inline int cgroup_bpf_inherit(struct cgroup *cgrp) { return 0; }
 #define BPF_CGROUP_RUN_PROG_INET4_CONNECT_LOCK(sk, uaddr) ({ 0; })
 #define BPF_CGROUP_RUN_PROG_INET6_CONNECT(sk, uaddr) ({ 0; })
 #define BPF_CGROUP_RUN_PROG_INET6_CONNECT_LOCK(sk, uaddr) ({ 0; })
+#define BPF_CGROUP_RUN_PROG_UDP4_SENDMSG_LOCK(sk, uaddr, t_ctx) ({ 0; })
+#define BPF_CGROUP_RUN_PROG_UDP6_SENDMSG_LOCK(sk, uaddr, t_ctx) ({ 0; })
 #define BPF_CGROUP_RUN_PROG_SOCK_OPS(sock_ops) ({ 0; })
 #define BPF_CGROUP_RUN_PROG_DEVICE_CGROUP(type,major,minor,access) ({ 0; })
 
diff --git a/include/linux/filter.h b/include/linux/filter.h
index d358d18..d90abda 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -1010,6 +1010,7 @@ struct bpf_sock_addr_kern {
 	 * only two (src and dst) are available at convert_ctx_access time
 	 */
 	u64 tmp_reg;
+	void *t_ctx;	/* Attach type specific context. */
 };
 
 struct bpf_sock_ops_kern {
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 97446bb..b70ad2c 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -158,6 +158,8 @@ enum bpf_attach_type {
 	BPF_CGROUP_INET6_CONNECT,
 	BPF_CGROUP_INET4_POST_BIND,
 	BPF_CGROUP_INET6_POST_BIND,
+	BPF_CGROUP_UDP4_SENDMSG,
+	BPF_CGROUP_UDP6_SENDMSG,
 	__MAX_BPF_ATTACH_TYPE
 };
 
@@ -2247,6 +2249,12 @@ struct bpf_sock_addr {
 	__u32 family;		/* Allows 4-byte read, but no write */
 	__u32 type;		/* Allows 4-byte read, but no write */
 	__u32 protocol;		/* Allows 4-byte read, but no write */
+	__u32 msg_src_ip4;	/* Allows 1,2,4-byte read an 4-byte write.
+				 * Stored in network byte order.
+				 */
+	__u32 msg_src_ip6[4];	/* Allows 1,2,4-byte read an 4-byte write.
+				 * Stored in network byte order.
+				 */
 };
 
 /* User bpf_sock_ops struct to access socket values and specify request ops
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 43171a0..f7c00bd 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -500,6 +500,7 @@ EXPORT_SYMBOL(__cgroup_bpf_run_filter_sk);
  * @sk: sock struct that will use sockaddr
  * @uaddr: sockaddr struct provided by user
  * @type: The type of program to be exectuted
+ * @t_ctx: Pointer to attach type specific context
  *
  * socket is expected to be of type INET or INET6.
  *
@@ -508,12 +509,15 @@ EXPORT_SYMBOL(__cgroup_bpf_run_filter_sk);
  */
 int __cgroup_bpf_run_filter_sock_addr(struct sock *sk,
 				      struct sockaddr *uaddr,
-				      enum bpf_attach_type type)
+				      enum bpf_attach_type type,
+				      void *t_ctx)
 {
 	struct bpf_sock_addr_kern ctx = {
 		.sk = sk,
 		.uaddr = uaddr,
+		.t_ctx = t_ctx,
 	};
+	struct sockaddr_storage unspec;
 	struct cgroup *cgrp;
 	int ret;
 
@@ -523,6 +527,11 @@ int __cgroup_bpf_run_filter_sock_addr(struct sock *sk,
 	if (sk->sk_family != AF_INET && sk->sk_family != AF_INET6)
 		return 0;
 
+	if (!ctx.uaddr) {
+		memset(&unspec, 0, sizeof(unspec));
+		ctx.uaddr = (struct sockaddr *)&unspec;
+	}
+
 	cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
 	ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], &ctx, BPF_PROG_RUN);
 
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index bfcde94..11a5a95 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1247,6 +1247,8 @@ bpf_prog_load_check_attach_type(enum bpf_prog_type prog_type,
 		case BPF_CGROUP_INET6_BIND:
 		case BPF_CGROUP_INET4_CONNECT:
 		case BPF_CGROUP_INET6_CONNECT:
+		case BPF_CGROUP_UDP4_SENDMSG:
+		case BPF_CGROUP_UDP6_SENDMSG:
 			return 0;
 		default:
 			return -EINVAL;
@@ -1563,6 +1565,8 @@ static int bpf_prog_attach(const union bpf_attr *attr)
 	case BPF_CGROUP_INET6_BIND:
 	case BPF_CGROUP_INET4_CONNECT:
 	case BPF_CGROUP_INET6_CONNECT:
+	case BPF_CGROUP_UDP4_SENDMSG:
+	case BPF_CGROUP_UDP6_SENDMSG:
 		ptype = BPF_PROG_TYPE_CGROUP_SOCK_ADDR;
 		break;
 	case BPF_CGROUP_SOCK_OPS:
@@ -1633,6 +1637,8 @@ static int bpf_prog_detach(const union bpf_attr *attr)
 	case BPF_CGROUP_INET6_BIND:
 	case BPF_CGROUP_INET4_CONNECT:
 	case BPF_CGROUP_INET6_CONNECT:
+	case BPF_CGROUP_UDP4_SENDMSG:
+	case BPF_CGROUP_UDP6_SENDMSG:
 		ptype = BPF_PROG_TYPE_CGROUP_SOCK_ADDR;
 		break;
 	case BPF_CGROUP_SOCK_OPS:
@@ -1690,6 +1696,8 @@ static int bpf_prog_query(const union bpf_attr *attr,
 	case BPF_CGROUP_INET6_POST_BIND:
 	case BPF_CGROUP_INET4_CONNECT:
 	case BPF_CGROUP_INET6_CONNECT:
+	case BPF_CGROUP_UDP4_SENDMSG:
+	case BPF_CGROUP_UDP6_SENDMSG:
 	case BPF_CGROUP_SOCK_OPS:
 	case BPF_CGROUP_DEVICE:
 		break;
diff --git a/net/core/filter.c b/net/core/filter.c
index ba3ff5a..0e54ac1 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5038,6 +5038,7 @@ static bool sock_addr_is_valid_access(int off, int size,
 		switch (prog->expected_attach_type) {
 		case BPF_CGROUP_INET4_BIND:
 		case BPF_CGROUP_INET4_CONNECT:
+		case BPF_CGROUP_UDP4_SENDMSG:
 			break;
 		default:
 			return false;
@@ -5047,6 +5048,24 @@ static bool sock_addr_is_valid_access(int off, int size,
 		switch (prog->expected_attach_type) {
 		case BPF_CGROUP_INET6_BIND:
 		case BPF_CGROUP_INET6_CONNECT:
+		case BPF_CGROUP_UDP6_SENDMSG:
+			break;
+		default:
+			return false;
+		}
+		break;
+	case bpf_ctx_range(struct bpf_sock_addr, msg_src_ip4):
+		switch (prog->expected_attach_type) {
+		case BPF_CGROUP_UDP4_SENDMSG:
+			break;
+		default:
+			return false;
+		}
+		break;
+	case bpf_ctx_range_till(struct bpf_sock_addr, msg_src_ip6[0],
+				msg_src_ip6[3]):
+		switch (prog->expected_attach_type) {
+		case BPF_CGROUP_UDP6_SENDMSG:
 			break;
 		default:
 			return false;
@@ -5057,6 +5076,9 @@ static bool sock_addr_is_valid_access(int off, int size,
 	switch (off) {
 	case bpf_ctx_range(struct bpf_sock_addr, user_ip4):
 	case bpf_ctx_range_till(struct bpf_sock_addr, user_ip6[0], user_ip6[3]):
+	case bpf_ctx_range(struct bpf_sock_addr, msg_src_ip4):
+	case bpf_ctx_range_till(struct bpf_sock_addr, msg_src_ip6[0],
+				msg_src_ip6[3]):
 		/* Only narrow read access allowed for now. */
 		if (type == BPF_READ) {
 			bpf_ctx_record_field_size(info, size_default);
@@ -5811,6 +5833,23 @@ static u32 sock_addr_convert_ctx_access(enum bpf_access_type type,
 		*insn++ = BPF_ALU32_IMM(BPF_RSH, si->dst_reg,
 					SK_FL_PROTO_SHIFT);
 		break;
+
+	case offsetof(struct bpf_sock_addr, msg_src_ip4):
+		/* Treat t_ctx as struct in_addr for msg_src_ip4. */
+		SOCK_ADDR_LOAD_OR_STORE_NESTED_FIELD_SIZE_OFF(
+			struct bpf_sock_addr_kern, struct in_addr, t_ctx,
+			s_addr, BPF_SIZE(si->code), 0, tmp_reg);
+		break;
+
+	case bpf_ctx_range_till(struct bpf_sock_addr, msg_src_ip6[0],
+				msg_src_ip6[3]):
+		off = si->off;
+		off -= offsetof(struct bpf_sock_addr, msg_src_ip6[0]);
+		/* Treat t_ctx as struct in6_addr for msg_src_ip6. */
+		SOCK_ADDR_LOAD_OR_STORE_NESTED_FIELD_SIZE_OFF(
+			struct bpf_sock_addr_kern, struct in6_addr, t_ctx,
+			s6_addr32[0], BPF_SIZE(si->code), off, tmp_reg);
+		break;
 	}
 
 	return insn - insn_buf;
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index ff4d4ba..a1f9ba2 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -900,6 +900,7 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 {
 	struct inet_sock *inet = inet_sk(sk);
 	struct udp_sock *up = udp_sk(sk);
+	DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name);
 	struct flowi4 fl4_stack;
 	struct flowi4 *fl4;
 	int ulen = len;
@@ -954,8 +955,7 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	/*
 	 *	Get and verify the address.
 	 */
-	if (msg->msg_name) {
-		DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name);
+	if (usin) {
 		if (msg->msg_namelen < sizeof(*usin))
 			return -EINVAL;
 		if (usin->sin_family != AF_INET) {
@@ -1009,6 +1009,22 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 		rcu_read_unlock();
 	}
 
+	if (!connected) {
+		err = BPF_CGROUP_RUN_PROG_UDP4_SENDMSG_LOCK(sk,
+					    (struct sockaddr *)usin, &ipc.addr);
+		if (err)
+			goto out_free;
+		if (usin) {
+			if (usin->sin_port == 0) {
+				/* BPF program set invalid port. Reject it. */
+				err = -EINVAL;
+				goto out_free;
+			}
+			daddr = usin->sin_addr.s_addr;
+			dport = usin->sin_port;
+		}
+	}
+
 	saddr = ipc.addr;
 	ipc.addr = faddr = daddr;
 
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 2839c1b..67c44b5 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1315,6 +1315,29 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 		fl6.saddr = np->saddr;
 	fl6.fl6_sport = inet->inet_sport;
 
+	if (!connected) {
+		err = BPF_CGROUP_RUN_PROG_UDP6_SENDMSG_LOCK(sk,
+					   (struct sockaddr *)sin6, &fl6.saddr);
+		if (err)
+			goto out_no_dst;
+		if (sin6) {
+			if (ipv6_addr_v4mapped(&sin6->sin6_addr)) {
+				/* BPF program rewrote IPv6-only by IPv4-mapped
+				 * IPv6. It's currently unsupported.
+				 */
+				err = -ENOTSUPP;
+				goto out_no_dst;
+			}
+			if (sin6->sin6_port == 0) {
+				/* BPF program set invalid port. Reject it. */
+				err = -EINVAL;
+				goto out_no_dst;
+			}
+			fl6.fl6_dport = sin6->sin6_port;
+			fl6.daddr = sin6->sin6_addr;
+		}
+	}
+
 	final_p = fl6_update_dst(&fl6, opt, &final);
 	if (final_p)
 		connected = false;
@@ -1394,6 +1417,7 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 
 out:
 	dst_release(dst);
+out_no_dst:
 	fl6_sock_release(flowlabel);
 	txopt_put(opt_to_free);
 	if (!err)
-- 
2.9.5

[PATCH v2 bpf-next 2/5] bpf: Sync bpf.h to tools/

[Andrey Ignatov]

Sync new `BPF_CGROUP_UDP4_SENDMSG` and `BPF_CGROUP_UDP6_SENDMSG`
attach types to tools/.

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
---
 tools/include/uapi/linux/bpf.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 97446bb..b70ad2c 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -158,6 +158,8 @@ enum bpf_attach_type {
 	BPF_CGROUP_INET6_CONNECT,
 	BPF_CGROUP_INET4_POST_BIND,
 	BPF_CGROUP_INET6_POST_BIND,
+	BPF_CGROUP_UDP4_SENDMSG,
+	BPF_CGROUP_UDP6_SENDMSG,
 	__MAX_BPF_ATTACH_TYPE
 };
 
@@ -2247,6 +2249,12 @@ struct bpf_sock_addr {
 	__u32 family;		/* Allows 4-byte read, but no write */
 	__u32 type;		/* Allows 4-byte read, but no write */
 	__u32 protocol;		/* Allows 4-byte read, but no write */
+	__u32 msg_src_ip4;	/* Allows 1,2,4-byte read an 4-byte write.
+				 * Stored in network byte order.
+				 */
+	__u32 msg_src_ip6[4];	/* Allows 1,2,4-byte read an 4-byte write.
+				 * Stored in network byte order.
+				 */
 };
 
 /* User bpf_sock_ops struct to access socket values and specify request ops
-- 
2.9.5

[PATCH v2 bpf-next 3/5] libbpf: Support guessing sendmsg{4,6} progs

[Andrey Ignatov]

libbpf can guess prog type and expected attach type based on section
name. Add hints for "cgroup/sendmsg4" and "cgroup/sendmsg6" section
names.

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
---
 tools/lib/bpf/libbpf.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 3dbe217..f5238c5 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2042,6 +2042,8 @@ static const struct {
 	BPF_SA_PROG_SEC("cgroup/bind6",	BPF_CGROUP_INET6_BIND),
 	BPF_SA_PROG_SEC("cgroup/connect4", BPF_CGROUP_INET4_CONNECT),
 	BPF_SA_PROG_SEC("cgroup/connect6", BPF_CGROUP_INET6_CONNECT),
+	BPF_SA_PROG_SEC("cgroup/sendmsg4", BPF_CGROUP_UDP4_SENDMSG),
+	BPF_SA_PROG_SEC("cgroup/sendmsg6", BPF_CGROUP_UDP6_SENDMSG),
 	BPF_S_PROG_SEC("cgroup/post_bind4", BPF_CGROUP_INET4_POST_BIND),
 	BPF_S_PROG_SEC("cgroup/post_bind6", BPF_CGROUP_INET6_POST_BIND),
 };
-- 
2.9.5

[PATCH v2 bpf-next 4/5] selftests/bpf: Prepare test_sock_addr for extension

[Andrey Ignatov]

test_sock_addr was not easy to extend since it was focused on sys_bind
and sys_connect quite a bit.

Reorganized it so that it'll be easier to cover new test-cases for
`BPF_PROG_TYPE_CGROUP_SOCK_ADDR`:

- decouple test-cases so that only one BPF prog is tested at a time;

- check programmatically that local IP:port for sys_bind, source IP and
  destination IP:port for sys_connect are rewritten property by tested
  BPF programs.

The output of new version:
  # test_sock_addr.sh 2>/dev/null
  Wait for testing IPv4/IPv6 to become available ... OK
  Test case: bind4: load prog with wrong expected attach type .. [PASS]
  Test case: bind4: attach prog with wrong attach type .. [PASS]
  Test case: bind4: rewrite IP & TCP port in .. [PASS]
  Test case: bind4: rewrite IP & UDP port in .. [PASS]
  Test case: bind6: load prog with wrong expected attach type .. [PASS]
  Test case: bind6: attach prog with wrong attach type .. [PASS]
  Test case: bind6: rewrite IP & TCP port in .. [PASS]
  Test case: bind6: rewrite IP & UDP port in .. [PASS]
  Test case: connect4: load prog with wrong expected attach type .. [PASS]
  Test case: connect4: attach prog with wrong attach type .. [PASS]
  Test case: connect4: rewrite IP & TCP port .. [PASS]
  Test case: connect4: rewrite IP & UDP port .. [PASS]
  Test case: connect6: load prog with wrong expected attach type .. [PASS]
  Test case: connect6: attach prog with wrong attach type .. [PASS]
  Test case: connect6: rewrite IP & TCP port .. [PASS]
  Test case: connect6: rewrite IP & UDP port .. [PASS]
  Summary: 16 PASSED, 0 FAILED

(stderr contains errors from libbpf when testing load/attach with
invalid arguments)

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
---
 tools/testing/selftests/bpf/test_sock_addr.c | 655 +++++++++++++++++++--------
 1 file changed, 460 insertions(+), 195 deletions(-)

diff --git a/tools/testing/selftests/bpf/test_sock_addr.c b/tools/testing/selftests/bpf/test_sock_addr.c
index 2950f80..ed3e397 100644
--- a/tools/testing/selftests/bpf/test_sock_addr.c
+++ b/tools/testing/selftests/bpf/test_sock_addr.c
@@ -17,34 +17,292 @@
 #include "cgroup_helpers.h"
 #include "bpf_rlimit.h"
 
+#ifndef ARRAY_SIZE
+# define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+#endif
+
 #define CG_PATH	"/foo"
 #define CONNECT4_PROG_PATH	"./connect4_prog.o"
 #define CONNECT6_PROG_PATH	"./connect6_prog.o"
 
 #define SERV4_IP		"192.168.1.254"
 #define SERV4_REWRITE_IP	"127.0.0.1"
+#define SRC4_REWRITE_IP		"127.0.0.4"
 #define SERV4_PORT		4040
 #define SERV4_REWRITE_PORT	4444
 
 #define SERV6_IP		"face:b00c:1234:5678::abcd"
 #define SERV6_REWRITE_IP	"::1"
+#define SRC6_REWRITE_IP		"::6"
 #define SERV6_PORT		6060
 #define SERV6_REWRITE_PORT	6666
 
 #define INET_NTOP_BUF	40
 
-typedef int (*load_fn)(enum bpf_attach_type, const char *comment);
+struct sock_addr_test;
+
+typedef int (*load_fn)(const struct sock_addr_test *test);
 typedef int (*info_fn)(int, struct sockaddr *, socklen_t *);
 
-struct program {
-	enum bpf_attach_type type;
-	load_fn	loadfn;
-	int fd;
-	const char *name;
-	enum bpf_attach_type invalid_type;
+char bpf_log_buf[BPF_LOG_BUF_SIZE];
+
+struct sock_addr_test {
+	const char *descr;
+	/* BPF prog properties */
+	load_fn loadfn;
+	enum bpf_attach_type expected_attach_type;
+	enum bpf_attach_type attach_type;
+	/* Socket properties */
+	int domain;
+	int type;
+	/* IP:port pairs for BPF prog to override */
+	const char *requested_ip;
+	unsigned short requested_port;
+	const char *expected_ip;
+	unsigned short expected_port;
+	const char *expected_src_ip;
+	/* Expected test result */
+	enum {
+		LOAD_REJECT,
+		ATTACH_REJECT,
+		SUCCESS,
+	} expected_result;
 };
 
-char bpf_log_buf[BPF_LOG_BUF_SIZE];
+static int bind4_prog_load(const struct sock_addr_test *test);
+static int bind6_prog_load(const struct sock_addr_test *test);
+static int connect4_prog_load(const struct sock_addr_test *test);
+static int connect6_prog_load(const struct sock_addr_test *test);
+
+static struct sock_addr_test tests[] = {
+	/* bind */
+	{
+		"bind4: load prog with wrong expected attach type",
+		bind4_prog_load,
+		BPF_CGROUP_INET6_BIND,
+		BPF_CGROUP_INET4_BIND,
+		AF_INET,
+		SOCK_STREAM,
+		NULL,
+		0,
+		NULL,
+		0,
+		NULL,
+		LOAD_REJECT,
+	},
+	{
+		"bind4: attach prog with wrong attach type",
+		bind4_prog_load,
+		BPF_CGROUP_INET4_BIND,
+		BPF_CGROUP_INET6_BIND,
+		AF_INET,
+		SOCK_STREAM,
+		NULL,
+		0,
+		NULL,
+		0,
+		NULL,
+		ATTACH_REJECT,
+	},
+	{
+		"bind4: rewrite IP & TCP port in",
+		bind4_prog_load,
+		BPF_CGROUP_INET4_BIND,
+		BPF_CGROUP_INET4_BIND,
+		AF_INET,
+		SOCK_STREAM,
+		SERV4_IP,
+		SERV4_PORT,
+		SERV4_REWRITE_IP,
+		SERV4_REWRITE_PORT,
+		NULL,
+		SUCCESS,
+	},
+	{
+		"bind4: rewrite IP & UDP port in",
+		bind4_prog_load,
+		BPF_CGROUP_INET4_BIND,
+		BPF_CGROUP_INET4_BIND,
+		AF_INET,
+		SOCK_DGRAM,
+		SERV4_IP,
+		SERV4_PORT,
+		SERV4_REWRITE_IP,
+		SERV4_REWRITE_PORT,
+		NULL,
+		SUCCESS,
+	},
+	{
+		"bind6: load prog with wrong expected attach type",
+		bind6_prog_load,
+		BPF_CGROUP_INET4_BIND,
+		BPF_CGROUP_INET6_BIND,
+		AF_INET6,
+		SOCK_STREAM,
+		NULL,
+		0,
+		NULL,
+		0,
+		NULL,
+		LOAD_REJECT,
+	},
+	{
+		"bind6: attach prog with wrong attach type",
+		bind6_prog_load,
+		BPF_CGROUP_INET6_BIND,
+		BPF_CGROUP_INET4_BIND,
+		AF_INET,
+		SOCK_STREAM,
+		NULL,
+		0,
+		NULL,
+		0,
+		NULL,
+		ATTACH_REJECT,
+	},
+	{
+		"bind6: rewrite IP & TCP port in",
+		bind6_prog_load,
+		BPF_CGROUP_INET6_BIND,
+		BPF_CGROUP_INET6_BIND,
+		AF_INET6,
+		SOCK_STREAM,
+		SERV6_IP,
+		SERV6_PORT,
+		SERV6_REWRITE_IP,
+		SERV6_REWRITE_PORT,
+		NULL,
+		SUCCESS,
+	},
+	{
+		"bind6: rewrite IP & UDP port in",
+		bind6_prog_load,
+		BPF_CGROUP_INET6_BIND,
+		BPF_CGROUP_INET6_BIND,
+		AF_INET6,
+		SOCK_DGRAM,
+		SERV6_IP,
+		SERV6_PORT,
+		SERV6_REWRITE_IP,
+		SERV6_REWRITE_PORT,
+		NULL,
+		SUCCESS,
+	},
+
+	/* connect */
+	{
+		"connect4: load prog with wrong expected attach type",
+		connect4_prog_load,
+		BPF_CGROUP_INET6_CONNECT,
+		BPF_CGROUP_INET4_CONNECT,
+		AF_INET,
+		SOCK_STREAM,
+		NULL,
+		0,
+		NULL,
+		0,
+		NULL,
+		LOAD_REJECT,
+	},
+	{
+		"connect4: attach prog with wrong attach type",
+		connect4_prog_load,
+		BPF_CGROUP_INET4_CONNECT,
+		BPF_CGROUP_INET6_CONNECT,
+		AF_INET,
+		SOCK_STREAM,
+		NULL,
+		0,
+		NULL,
+		0,
+		NULL,
+		ATTACH_REJECT,
+	},
+	{
+		"connect4: rewrite IP & TCP port",
+		connect4_prog_load,
+		BPF_CGROUP_INET4_CONNECT,
+		BPF_CGROUP_INET4_CONNECT,
+		AF_INET,
+		SOCK_STREAM,
+		SERV4_IP,
+		SERV4_PORT,
+		SERV4_REWRITE_IP,
+		SERV4_REWRITE_PORT,
+		SRC4_REWRITE_IP,
+		SUCCESS,
+	},
+	{
+		"connect4: rewrite IP & UDP port",
+		connect4_prog_load,
+		BPF_CGROUP_INET4_CONNECT,
+		BPF_CGROUP_INET4_CONNECT,
+		AF_INET,
+		SOCK_DGRAM,
+		SERV4_IP,
+		SERV4_PORT,
+		SERV4_REWRITE_IP,
+		SERV4_REWRITE_PORT,
+		SRC4_REWRITE_IP,
+		SUCCESS,
+	},
+	{
+		"connect6: load prog with wrong expected attach type",
+		connect6_prog_load,
+		BPF_CGROUP_INET4_CONNECT,
+		BPF_CGROUP_INET6_CONNECT,
+		AF_INET6,
+		SOCK_STREAM,
+		NULL,
+		0,
+		NULL,
+		0,
+		NULL,
+		LOAD_REJECT,
+	},
+	{
+		"connect6: attach prog with wrong attach type",
+		connect6_prog_load,
+		BPF_CGROUP_INET6_CONNECT,
+		BPF_CGROUP_INET4_CONNECT,
+		AF_INET,
+		SOCK_STREAM,
+		NULL,
+		0,
+		NULL,
+		0,
+		NULL,
+		ATTACH_REJECT,
+	},
+	{
+		"connect6: rewrite IP & TCP port",
+		connect6_prog_load,
+		BPF_CGROUP_INET6_CONNECT,
+		BPF_CGROUP_INET6_CONNECT,
+		AF_INET6,
+		SOCK_STREAM,
+		SERV6_IP,
+		SERV6_PORT,
+		SERV6_REWRITE_IP,
+		SERV6_REWRITE_PORT,
+		SRC6_REWRITE_IP,
+		SUCCESS,
+	},
+	{
+		"connect6: rewrite IP & UDP port",
+		connect6_prog_load,
+		BPF_CGROUP_INET6_CONNECT,
+		BPF_CGROUP_INET6_CONNECT,
+		AF_INET6,
+		SOCK_DGRAM,
+		SERV6_IP,
+		SERV6_PORT,
+		SERV6_REWRITE_IP,
+		SERV6_REWRITE_PORT,
+		SRC6_REWRITE_IP,
+		SUCCESS,
+	},
+};
 
 static int mk_sockaddr(int domain, const char *ip, unsigned short port,
 		       struct sockaddr *addr, socklen_t addr_len)
@@ -84,25 +342,23 @@ static int mk_sockaddr(int domain, const char *ip, unsigned short port,
 	return 0;
 }
 
-static int load_insns(enum bpf_attach_type attach_type,
-		      const struct bpf_insn *insns, size_t insns_cnt,
-		      const char *comment)
+static int load_insns(const struct sock_addr_test *test,
+		      const struct bpf_insn *insns, size_t insns_cnt)
 {
 	struct bpf_load_program_attr load_attr;
 	int ret;
 
 	memset(&load_attr, 0, sizeof(struct bpf_load_program_attr));
 	load_attr.prog_type = BPF_PROG_TYPE_CGROUP_SOCK_ADDR;
-	load_attr.expected_attach_type = attach_type;
+	load_attr.expected_attach_type = test->expected_attach_type;
 	load_attr.insns = insns;
 	load_attr.insns_cnt = insns_cnt;
 	load_attr.license = "GPL";
 
 	ret = bpf_load_program_xattr(&load_attr, bpf_log_buf, BPF_LOG_BUF_SIZE);
-	if (ret < 0 && comment) {
-		log_err(">>> Loading %s program error.\n"
-			">>> Output from verifier:\n%s\n-------\n",
-			comment, bpf_log_buf);
+	if (ret < 0 && test->expected_result != LOAD_REJECT) {
+		log_err(">>> Loading program error.\n"
+			">>> Verifier output:\n%s\n-------\n", bpf_log_buf);
 	}
 
 	return ret;
@@ -119,8 +375,7 @@ static int load_insns(enum bpf_attach_type attach_type,
  * to count jumps properly.
  */
 
-static int bind4_prog_load(enum bpf_attach_type attach_type,
-			   const char *comment)
+static int bind4_prog_load(const struct sock_addr_test *test)
 {
 	union {
 		uint8_t u4_addr8[4];
@@ -186,12 +441,10 @@ static int bind4_prog_load(enum bpf_attach_type attach_type,
 		BPF_EXIT_INSN(),
 	};
 
-	return load_insns(attach_type, insns,
-			  sizeof(insns) / sizeof(struct bpf_insn), comment);
+	return load_insns(test, insns, sizeof(insns) / sizeof(struct bpf_insn));
 }
 
-static int bind6_prog_load(enum bpf_attach_type attach_type,
-			   const char *comment)
+static int bind6_prog_load(const struct sock_addr_test *test)
 {
 	struct sockaddr_in6 addr6_rw;
 	struct in6_addr ip6;
@@ -254,13 +507,10 @@ static int bind6_prog_load(enum bpf_attach_type attach_type,
 		BPF_EXIT_INSN(),
 	};
 
-	return load_insns(attach_type, insns,
-			  sizeof(insns) / sizeof(struct bpf_insn), comment);
+	return load_insns(test, insns, sizeof(insns) / sizeof(struct bpf_insn));
 }
 
-static int connect_prog_load_path(const char *path,
-				  enum bpf_attach_type attach_type,
-				  const char *comment)
+static int load_path(const struct sock_addr_test *test, const char *path)
 {
 	struct bpf_prog_load_attr attr;
 	struct bpf_object *obj;
@@ -269,75 +519,83 @@ static int connect_prog_load_path(const char *path,
 	memset(&attr, 0, sizeof(struct bpf_prog_load_attr));
 	attr.file = path;
 	attr.prog_type = BPF_PROG_TYPE_CGROUP_SOCK_ADDR;
-	attr.expected_attach_type = attach_type;
+	attr.expected_attach_type = test->expected_attach_type;
 
 	if (bpf_prog_load_xattr(&attr, &obj, &prog_fd)) {
-		if (comment)
-			log_err(">>> Loading %s program at %s error.\n",
-				comment, path);
+		if (test->expected_result != LOAD_REJECT)
+			log_err(">>> Loading program (%s) error.\n", path);
 		return -1;
 	}
 
 	return prog_fd;
 }
 
-static int connect4_prog_load(enum bpf_attach_type attach_type,
-			      const char *comment)
+static int connect4_prog_load(const struct sock_addr_test *test)
 {
-	return connect_prog_load_path(CONNECT4_PROG_PATH, attach_type, comment);
+	return load_path(test, CONNECT4_PROG_PATH);
 }
 
-static int connect6_prog_load(enum bpf_attach_type attach_type,
-			      const char *comment)
+static int connect6_prog_load(const struct sock_addr_test *test)
 {
-	return connect_prog_load_path(CONNECT6_PROG_PATH, attach_type, comment);
+	return load_path(test, CONNECT6_PROG_PATH);
 }
 
-static void print_ip_port(int sockfd, info_fn fn, const char *fmt)
+static int cmp_addr(const struct sockaddr_storage *addr1,
+		    const struct sockaddr_storage *addr2, int cmp_port)
 {
-	char addr_buf[INET_NTOP_BUF];
-	struct sockaddr_storage addr;
-	struct sockaddr_in6 *addr6;
-	struct sockaddr_in *addr4;
-	socklen_t addr_len;
-	unsigned short port;
-	void *nip;
-
-	addr_len = sizeof(struct sockaddr_storage);
-	memset(&addr, 0, addr_len);
-
-	if (fn(sockfd, (struct sockaddr *)&addr, (socklen_t *)&addr_len) == 0) {
-		if (addr.ss_family == AF_INET) {
-			addr4 = (struct sockaddr_in *)&addr;
-			nip = (void *)&addr4->sin_addr;
-			port = ntohs(addr4->sin_port);
-		} else if (addr.ss_family == AF_INET6) {
-			addr6 = (struct sockaddr_in6 *)&addr;
-			nip = (void *)&addr6->sin6_addr;
-			port = ntohs(addr6->sin6_port);
-		} else {
-			return;
-		}
-		const char *addr_str =
-			inet_ntop(addr.ss_family, nip, addr_buf, INET_NTOP_BUF);
-		printf(fmt, addr_str ? addr_str : "??", port);
+	const struct sockaddr_in *four1, *four2;
+	const struct sockaddr_in6 *six1, *six2;
+
+	if (addr1->ss_family != addr2->ss_family)
+		return -1;
+
+	if (addr1->ss_family == AF_INET) {
+		four1 = (const struct sockaddr_in *)addr1;
+		four2 = (const struct sockaddr_in *)addr2;
+		return !((four1->sin_port == four2->sin_port || !cmp_port) &&
+			 four1->sin_addr.s_addr == four2->sin_addr.s_addr);
+	} else if (addr1->ss_family == AF_INET6) {
+		six1 = (const struct sockaddr_in6 *)addr1;
+		six2 = (const struct sockaddr_in6 *)addr2;
+		return !((six1->sin6_port == six2->sin6_port || !cmp_port) &&
+			 !memcmp(&six1->sin6_addr, &six2->sin6_addr,
+				 sizeof(struct in6_addr)));
 	}
+
+	return -1;
+}
+
+static int cmp_sock_addr(info_fn fn, int sock1,
+			 const struct sockaddr_storage *addr2, int cmp_port)
+{
+	struct sockaddr_storage addr1;
+	socklen_t len1 = sizeof(addr1);
+
+	memset(&addr1, 0, len1);
+	if (fn(sock1, (struct sockaddr *)&addr1, (socklen_t *)&len1) != 0)
+		return -1;
+
+	return cmp_addr(&addr1, addr2, cmp_port);
+}
+
+static int cmp_local_ip(int sock1, const struct sockaddr_storage *addr2)
+{
+	return cmp_sock_addr(getsockname, sock1, addr2, /*cmp_port*/ 0);
 }
 
-static void print_local_ip_port(int sockfd, const char *fmt)
+static int cmp_local_addr(int sock1, const struct sockaddr_storage *addr2)
 {
-	print_ip_port(sockfd, getsockname, fmt);
+	return cmp_sock_addr(getsockname, sock1, addr2, /*cmp_port*/ 1);
 }
 
-static void print_remote_ip_port(int sockfd, const char *fmt)
+static int cmp_peer_addr(int sock1, const struct sockaddr_storage *addr2)
 {
-	print_ip_port(sockfd, getpeername, fmt);
+	return cmp_sock_addr(getpeername, sock1, addr2, /*cmp_port*/ 1);
 }
 
 static int start_server(int type, const struct sockaddr_storage *addr,
 			socklen_t addr_len)
 {
-
 	int fd;
 
 	fd = socket(addr->ss_family, type, 0);
@@ -358,8 +616,6 @@ static int start_server(int type, const struct sockaddr_storage *addr,
 		}
 	}
 
-	print_local_ip_port(fd, "\t   Actual: bind(%s, %d)\n");
-
 	goto out;
 close_out:
 	close(fd);
@@ -372,19 +628,19 @@ static int connect_to_server(int type, const struct sockaddr_storage *addr,
 			     socklen_t addr_len)
 {
 	int domain;
-	int fd;
+	int fd = -1;
 
 	domain = addr->ss_family;
 
 	if (domain != AF_INET && domain != AF_INET6) {
 		log_err("Unsupported address family");
-		return -1;
+		goto err;
 	}
 
 	fd = socket(domain, type, 0);
 	if (fd == -1) {
-		log_err("Failed to creating client socket");
-		return -1;
+		log_err("Failed to create client socket");
+		goto err;
 	}
 
 	if (connect(fd, (const struct sockaddr *)addr, addr_len) == -1) {
@@ -392,162 +648,188 @@ static int connect_to_server(int type, const struct sockaddr_storage *addr,
 		goto err;
 	}
 
-	print_remote_ip_port(fd, "\t   Actual: connect(%s, %d)");
-	print_local_ip_port(fd, " from (%s, %d)\n");
-
-	return 0;
+	goto out;
 err:
 	close(fd);
-	return -1;
+	fd = -1;
+out:
+	return fd;
 }
 
-static void print_test_case_num(int domain, int type)
+static int init_addrs(const struct sock_addr_test *test,
+		      struct sockaddr_storage *requested_addr,
+		      struct sockaddr_storage *expected_addr,
+		      struct sockaddr_storage *expected_src_addr)
 {
-	static int test_num;
-
-	printf("Test case #%d (%s/%s):\n", ++test_num,
-	       (domain == AF_INET ? "IPv4" :
-		domain == AF_INET6 ? "IPv6" :
-		"unknown_domain"),
-	       (type == SOCK_STREAM ? "TCP" :
-		type == SOCK_DGRAM ? "UDP" :
-		"unknown_type"));
+	socklen_t addr_len = sizeof(struct sockaddr_storage);
+
+	if (mk_sockaddr(test->domain, test->expected_ip, test->expected_port,
+			(struct sockaddr *)expected_addr, addr_len) == -1)
+		goto err;
+
+	if (mk_sockaddr(test->domain, test->requested_ip, test->requested_port,
+			(struct sockaddr *)requested_addr, addr_len) == -1)
+		goto err;
+
+	if (test->expected_src_ip &&
+	    mk_sockaddr(test->domain, test->expected_src_ip, 0,
+			(struct sockaddr *)expected_src_addr, addr_len) == -1)
+		goto err;
+
+	return 0;
+err:
+	return -1;
 }
 
-static int run_test_case(int domain, int type, const char *ip,
-			 unsigned short port)
+static int run_bind_test_case(const struct sock_addr_test *test)
 {
-	struct sockaddr_storage addr;
-	socklen_t addr_len = sizeof(addr);
+	socklen_t addr_len = sizeof(struct sockaddr_storage);
+	struct sockaddr_storage requested_addr;
+	struct sockaddr_storage expected_addr;
+	int clientfd = -1;
 	int servfd = -1;
 	int err = 0;
 
-	print_test_case_num(domain, type);
-
-	if (mk_sockaddr(domain, ip, port, (struct sockaddr *)&addr,
-			addr_len) == -1)
-		return -1;
+	if (init_addrs(test, &requested_addr, &expected_addr, NULL))
+		goto err;
 
-	printf("\tRequested: bind(%s, %d) ..\n", ip, port);
-	servfd = start_server(type, &addr, addr_len);
+	servfd = start_server(test->type, &requested_addr, addr_len);
 	if (servfd == -1)
 		goto err;
 
-	printf("\tRequested: connect(%s, %d) from (*, *) ..\n", ip, port);
-	if (connect_to_server(type, &addr, addr_len))
+	if (cmp_local_addr(servfd, &expected_addr))
+		goto err;
+
+	/* Try to connect to server just in case */
+	clientfd = connect_to_server(test->type, &expected_addr, addr_len);
+	if (clientfd == -1)
 		goto err;
 
 	goto out;
 err:
 	err = -1;
 out:
+	close(clientfd);
 	close(servfd);
 	return err;
 }
 
-static void close_progs_fds(struct program *progs, size_t prog_cnt)
+static int run_connect_test_case(const struct sock_addr_test *test)
 {
-	size_t i;
+	socklen_t addr_len = sizeof(struct sockaddr_storage);
+	struct sockaddr_storage expected_src_addr;
+	struct sockaddr_storage requested_addr;
+	struct sockaddr_storage expected_addr;
+	int clientfd = -1;
+	int servfd = -1;
+	int err = 0;
 
-	for (i = 0; i < prog_cnt; ++i) {
-		close(progs[i].fd);
-		progs[i].fd = -1;
-	}
-}
+	if (init_addrs(test, &requested_addr, &expected_addr,
+		       &expected_src_addr))
+		goto err;
 
-static int load_and_attach_progs(int cgfd, struct program *progs,
-				 size_t prog_cnt)
-{
-	size_t i;
-
-	for (i = 0; i < prog_cnt; ++i) {
-		printf("Load %s with invalid type (can pollute stderr) ",
-		       progs[i].name);
-		fflush(stdout);
-		progs[i].fd = progs[i].loadfn(progs[i].invalid_type, NULL);
-		if (progs[i].fd != -1) {
-			log_err("Load with invalid type accepted for %s",
-				progs[i].name);
-			goto err;
-		}
-		printf("... REJECTED\n");
+	/* Prepare server to connect to */
+	servfd = start_server(test->type, &expected_addr, addr_len);
+	if (servfd == -1)
+		goto err;
 
-		printf("Load %s with valid type", progs[i].name);
-		progs[i].fd = progs[i].loadfn(progs[i].type, progs[i].name);
-		if (progs[i].fd == -1) {
-			log_err("Failed to load program %s", progs[i].name);
-			goto err;
-		}
-		printf(" ... OK\n");
-
-		printf("Attach %s with invalid type", progs[i].name);
-		if (bpf_prog_attach(progs[i].fd, cgfd, progs[i].invalid_type,
-				    BPF_F_ALLOW_OVERRIDE) != -1) {
-			log_err("Attach with invalid type accepted for %s",
-				progs[i].name);
-			goto err;
-		}
-		printf(" ... REJECTED\n");
+	clientfd = connect_to_server(test->type, &requested_addr, addr_len);
+	if (clientfd == -1)
+		goto err;
 
-		printf("Attach %s with valid type", progs[i].name);
-		if (bpf_prog_attach(progs[i].fd, cgfd, progs[i].type,
-				    BPF_F_ALLOW_OVERRIDE) == -1) {
-			log_err("Failed to attach program %s", progs[i].name);
-			goto err;
-		}
-		printf(" ... OK\n");
-	}
+	/* Make sure src and dst addrs were overridden properly */
+	if (cmp_peer_addr(clientfd, &expected_addr))
+		goto err;
 
-	return 0;
+	if (cmp_local_ip(clientfd, &expected_src_addr))
+		goto err;
+
+	goto out;
 err:
-	close_progs_fds(progs, prog_cnt);
-	return -1;
+	err = -1;
+out:
+	close(clientfd);
+	close(servfd);
+	return err;
 }
 
-static int run_domain_test(int domain, int cgfd, struct program *progs,
-			   size_t prog_cnt, const char *ip, unsigned short port)
+static int run_test_case(int cgfd, const struct sock_addr_test *test)
 {
+	int progfd = -1;
 	int err = 0;
 
-	if (load_and_attach_progs(cgfd, progs, prog_cnt) == -1)
+	printf("Test case: %s .. ", test->descr);
+
+	progfd = test->loadfn(test);
+	if (test->expected_result == LOAD_REJECT && progfd < 0)
+		goto out;
+	else if (test->expected_result == LOAD_REJECT || progfd < 0)
+		goto err;
+
+	err = bpf_prog_attach(progfd, cgfd, test->attach_type,
+			      BPF_F_ALLOW_OVERRIDE);
+	if (test->expected_result == ATTACH_REJECT && err) {
+		err = 0; /* error was expected, reset it */
+		goto out;
+	} else if (test->expected_result == ATTACH_REJECT || err) {
 		goto err;
+	}
 
-	if (run_test_case(domain, SOCK_STREAM, ip, port) == -1)
+	switch (test->attach_type) {
+	case BPF_CGROUP_INET4_BIND:
+	case BPF_CGROUP_INET6_BIND:
+		err = run_bind_test_case(test);
+		break;
+	case BPF_CGROUP_INET4_CONNECT:
+	case BPF_CGROUP_INET6_CONNECT:
+		err = run_connect_test_case(test);
+		break;
+	default:
 		goto err;
+	}
 
-	if (run_test_case(domain, SOCK_DGRAM, ip, port) == -1)
+	if (err || test->expected_result != SUCCESS)
 		goto err;
 
 	goto out;
 err:
 	err = -1;
 out:
-	close_progs_fds(progs, prog_cnt);
+	/* Detaching w/o checking return code: best effort attempt. */
+	if (progfd != -1)
+		bpf_prog_detach(cgfd, test->attach_type);
+	close(progfd);
+	printf("[%s]\n", err ? "FAIL" : "PASS");
 	return err;
 }
 
-static int run_test(void)
+static int run_tests(int cgfd)
+{
+	int passes = 0;
+	int fails = 0;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(tests); ++i) {
+		if (run_test_case(cgfd, &tests[i]))
+			++fails;
+		else
+			++passes;
+	}
+	printf("Summary: %d PASSED, %d FAILED\n", passes, fails);
+	return fails ? -1 : 0;
+}
+
+int main(int argc, char **argv)
 {
-	size_t inet6_prog_cnt;
-	size_t inet_prog_cnt;
 	int cgfd = -1;
 	int err = 0;
 
-	struct program inet6_progs[] = {
-		{BPF_CGROUP_INET6_BIND, bind6_prog_load, -1, "bind6",
-		 BPF_CGROUP_INET4_BIND},
-		{BPF_CGROUP_INET6_CONNECT, connect6_prog_load, -1, "connect6",
-		 BPF_CGROUP_INET4_CONNECT},
-	};
-	inet6_prog_cnt = sizeof(inet6_progs) / sizeof(struct program);
-
-	struct program inet_progs[] = {
-		{BPF_CGROUP_INET4_BIND, bind4_prog_load, -1, "bind4",
-		 BPF_CGROUP_INET6_BIND},
-		{BPF_CGROUP_INET4_CONNECT, connect4_prog_load, -1, "connect4",
-		 BPF_CGROUP_INET6_CONNECT},
-	};
-	inet_prog_cnt = sizeof(inet_progs) / sizeof(struct program);
+	if (argc < 2) {
+		fprintf(stderr,
+			"%s has to be run via %s.sh. Skip direct run.\n",
+			argv[0], argv[0]);
+		exit(err);
+	}
 
 	if (setup_cgroup_environment())
 		goto err;
@@ -559,12 +841,7 @@ static int run_test(void)
 	if (join_cgroup(CG_PATH))
 		goto err;
 
-	if (run_domain_test(AF_INET, cgfd, inet_progs, inet_prog_cnt, SERV4_IP,
-			    SERV4_PORT) == -1)
-		goto err;
-
-	if (run_domain_test(AF_INET6, cgfd, inet6_progs, inet6_prog_cnt,
-			    SERV6_IP, SERV6_PORT) == -1)
+	if (run_tests(cgfd))
 		goto err;
 
 	goto out;
@@ -573,17 +850,5 @@ static int run_test(void)
 out:
 	close(cgfd);
 	cleanup_cgroup_environment();
-	printf(err ? "### FAIL\n" : "### SUCCESS\n");
 	return err;
 }
-
-int main(int argc, char **argv)
-{
-	if (argc < 2) {
-		fprintf(stderr,
-			"%s has to be run via %s.sh. Skip direct run.\n",
-			argv[0], argv[0]);
-		exit(0);
-	}
-	return run_test();
-}
-- 
2.9.5

[PATCH v2 bpf-next 5/5] selftests/bpf: Selftest for sys_sendmsg hooks

[Andrey Ignatov]

Add selftest for BPF_CGROUP_UDP4_SENDMSG and BPF_CGROUP_UDP6_SENDMSG
attach types.

Try to sendmsg(2) to specific IP:port and test that:
* source IP is overridden as expected.
* remote IP:port pair is overridden as expected;

Both UDPv4 and UDPv6 are tested.

Output:
  # test_sock_addr.sh 2>/dev/null
  Wait for testing IPv4/IPv6 to become available ... OK
  ... pre-existing test-cases skipped ...
  Test case: sendmsg4: load prog with wrong expected attach type .. [PASS]
  Test case: sendmsg4: attach prog with wrong attach type .. [PASS]
  Test case: sendmsg4: rewrite IP & port (asm) .. [PASS]
  Test case: sendmsg4: rewrite IP & port (C) .. [PASS]
  Test case: sendmsg4: deny call .. [PASS]
  Test case: sendmsg6: load prog with wrong expected attach type .. [PASS]
  Test case: sendmsg6: attach prog with wrong attach type .. [PASS]
  Test case: sendmsg6: rewrite IP & port (asm) .. [PASS]
  Test case: sendmsg6: rewrite IP & port (C) .. [PASS]
  Test case: sendmsg6: IPv4-mapped IPv6 .. [PASS]
  Test case: sendmsg6: deny call .. [PASS]
  Summary: 27 PASSED, 0 FAILED

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
---
 tools/testing/selftests/bpf/Makefile         |   3 +-
 tools/testing/selftests/bpf/sendmsg4_prog.c  |  49 +++
 tools/testing/selftests/bpf/sendmsg6_prog.c  |  60 ++++
 tools/testing/selftests/bpf/test_sock_addr.c | 518 +++++++++++++++++++++++++++
 4 files changed, 629 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/sendmsg4_prog.c
 create mode 100644 tools/testing/selftests/bpf/sendmsg6_prog.c

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 1eb0fa2..d87277a 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -33,7 +33,8 @@ TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test
 	sample_map_ret0.o test_tcpbpf_kern.o test_stacktrace_build_id.o \
 	sockmap_tcp_msg_prog.o connect4_prog.o connect6_prog.o test_adjust_tail.o \
 	test_btf_haskv.o test_btf_nokv.o test_sockmap_kern.o test_tunnel_kern.o \
-	test_get_stack_rawtp.o test_sockmap_kern.o test_sockhash_kern.o
+	test_get_stack_rawtp.o test_sockmap_kern.o test_sockhash_kern.o \
+	sendmsg4_prog.o sendmsg6_prog.o
 
 # Order correspond to 'make run_tests' order
 TEST_PROGS := test_kmod.sh \
diff --git a/tools/testing/selftests/bpf/sendmsg4_prog.c b/tools/testing/selftests/bpf/sendmsg4_prog.c
new file mode 100644
index 0000000..a91536b
--- /dev/null
+++ b/tools/testing/selftests/bpf/sendmsg4_prog.c
@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018 Facebook
+
+#include <linux/stddef.h>
+#include <linux/bpf.h>
+#include <sys/socket.h>
+
+#include "bpf_helpers.h"
+#include "bpf_endian.h"
+
+#define SRC1_IP4		0xAC100001U /* 172.16.0.1 */
+#define SRC2_IP4		0x00000000U
+#define SRC_REWRITE_IP4		0x7f000004U
+#define DST_IP4			0xC0A801FEU /* 192.168.1.254 */
+#define DST_REWRITE_IP4		0x7f000001U
+#define DST_PORT		4040
+#define DST_REWRITE_PORT4	4444
+
+int _version SEC("version") = 1;
+
+SEC("cgroup/sendmsg4")
+int sendmsg_v4_prog(struct bpf_sock_addr *ctx)
+{
+	if (ctx->type != SOCK_DGRAM)
+		return 0;
+
+	/* Rewrite source. */
+	if (ctx->msg_src_ip4 == bpf_htonl(SRC1_IP4) ||
+	    ctx->msg_src_ip4 == bpf_htonl(SRC2_IP4)) {
+		ctx->msg_src_ip4 = bpf_htonl(SRC_REWRITE_IP4);
+	} else {
+		/* Unexpected source. Reject sendmsg. */
+		return 0;
+	}
+
+	/* Rewrite destination. */
+	if ((ctx->user_ip4 >> 24) == (bpf_htonl(DST_IP4) >> 24) &&
+	     ctx->user_port == bpf_htons(DST_PORT)) {
+		ctx->user_ip4 = bpf_htonl(DST_REWRITE_IP4);
+		ctx->user_port = bpf_htons(DST_REWRITE_PORT4);
+	} else {
+		/* Unexpected source. Reject sendmsg. */
+		return 0;
+	}
+
+	return 1;
+}
+
+char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/sendmsg6_prog.c b/tools/testing/selftests/bpf/sendmsg6_prog.c
new file mode 100644
index 0000000..5aeaa28
--- /dev/null
+++ b/tools/testing/selftests/bpf/sendmsg6_prog.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018 Facebook
+
+#include <linux/stddef.h>
+#include <linux/bpf.h>
+#include <sys/socket.h>
+
+#include "bpf_helpers.h"
+#include "bpf_endian.h"
+
+#define SRC_REWRITE_IP6_0	0
+#define SRC_REWRITE_IP6_1	0
+#define SRC_REWRITE_IP6_2	0
+#define SRC_REWRITE_IP6_3	6
+
+#define DST_REWRITE_IP6_0	0
+#define DST_REWRITE_IP6_1	0
+#define DST_REWRITE_IP6_2	0
+#define DST_REWRITE_IP6_3	1
+
+#define DST_REWRITE_PORT6	6666
+
+int _version SEC("version") = 1;
+
+SEC("cgroup/sendmsg6")
+int sendmsg_v6_prog(struct bpf_sock_addr *ctx)
+{
+	if (ctx->type != SOCK_DGRAM)
+		return 0;
+
+	/* Rewrite source. */
+	if (ctx->msg_src_ip6[3] == bpf_htonl(1) ||
+	    ctx->msg_src_ip6[3] == bpf_htonl(0)) {
+		ctx->msg_src_ip6[0] = bpf_htonl(SRC_REWRITE_IP6_0);
+		ctx->msg_src_ip6[1] = bpf_htonl(SRC_REWRITE_IP6_1);
+		ctx->msg_src_ip6[2] = bpf_htonl(SRC_REWRITE_IP6_2);
+		ctx->msg_src_ip6[3] = bpf_htonl(SRC_REWRITE_IP6_3);
+	} else {
+		/* Unexpected source. Reject sendmsg. */
+		return 0;
+	}
+
+	/* Rewrite destination. */
+	if ((ctx->user_ip6[0] & 0xFFFF) == bpf_htons(0xFACE) &&
+	     ctx->user_ip6[0] >> 16 == bpf_htons(0xB00C)) {
+		ctx->user_ip6[0] = bpf_htonl(DST_REWRITE_IP6_0);
+		ctx->user_ip6[1] = bpf_htonl(DST_REWRITE_IP6_1);
+		ctx->user_ip6[2] = bpf_htonl(DST_REWRITE_IP6_2);
+		ctx->user_ip6[3] = bpf_htonl(DST_REWRITE_IP6_3);
+
+		ctx->user_port = bpf_htons(DST_REWRITE_PORT6);
+	} else {
+		/* Unexpected destination. Reject sendmsg. */
+		return 0;
+	}
+
+	return 1;
+}
+
+char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/test_sock_addr.c b/tools/testing/selftests/bpf/test_sock_addr.c
index ed3e397..a5e76b9 100644
--- a/tools/testing/selftests/bpf/test_sock_addr.c
+++ b/tools/testing/selftests/bpf/test_sock_addr.c
@@ -1,12 +1,16 @@
 // SPDX-License-Identifier: GPL-2.0
 // Copyright (c) 2018 Facebook
 
+#define _GNU_SOURCE
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 
 #include <arpa/inet.h>
+#include <netinet/in.h>
 #include <sys/types.h>
+#include <sys/select.h>
 #include <sys/socket.h>
 
 #include <linux/filter.h>
@@ -17,6 +21,10 @@
 #include "cgroup_helpers.h"
 #include "bpf_rlimit.h"
 
+#ifndef ENOTSUPP
+# define ENOTSUPP 524
+#endif
+
 #ifndef ARRAY_SIZE
 # define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
 #endif
@@ -24,15 +32,20 @@
 #define CG_PATH	"/foo"
 #define CONNECT4_PROG_PATH	"./connect4_prog.o"
 #define CONNECT6_PROG_PATH	"./connect6_prog.o"
+#define SENDMSG4_PROG_PATH	"./sendmsg4_prog.o"
+#define SENDMSG6_PROG_PATH	"./sendmsg6_prog.o"
 
 #define SERV4_IP		"192.168.1.254"
 #define SERV4_REWRITE_IP	"127.0.0.1"
+#define SRC4_IP			"172.16.0.1"
 #define SRC4_REWRITE_IP		"127.0.0.4"
 #define SERV4_PORT		4040
 #define SERV4_REWRITE_PORT	4444
 
 #define SERV6_IP		"face:b00c:1234:5678::abcd"
 #define SERV6_REWRITE_IP	"::1"
+#define SERV6_V4MAPPED_IP	"::ffff:192.168.0.4"
+#define SRC6_IP			"::1"
 #define SRC6_REWRITE_IP		"::6"
 #define SERV6_PORT		6060
 #define SERV6_REWRITE_PORT	6666
@@ -65,6 +78,8 @@ struct sock_addr_test {
 	enum {
 		LOAD_REJECT,
 		ATTACH_REJECT,
+		SYSCALL_EPERM,
+		SYSCALL_ENOTSUPP,
 		SUCCESS,
 	} expected_result;
 };
@@ -73,6 +88,12 @@ static int bind4_prog_load(const struct sock_addr_test *test);
 static int bind6_prog_load(const struct sock_addr_test *test);
 static int connect4_prog_load(const struct sock_addr_test *test);
 static int connect6_prog_load(const struct sock_addr_test *test);
+static int sendmsg_deny_prog_load(const struct sock_addr_test *test);
+static int sendmsg4_rw_asm_prog_load(const struct sock_addr_test *test);
+static int sendmsg4_rw_c_prog_load(const struct sock_addr_test *test);
+static int sendmsg6_rw_asm_prog_load(const struct sock_addr_test *test);
+static int sendmsg6_rw_c_prog_load(const struct sock_addr_test *test);
+static int sendmsg6_rw_v4mapped_prog_load(const struct sock_addr_test *test);
 
 static struct sock_addr_test tests[] = {
 	/* bind */
@@ -302,6 +323,162 @@ static struct sock_addr_test tests[] = {
 		SRC6_REWRITE_IP,
 		SUCCESS,
 	},
+
+	/* sendmsg */
+	{
+		"sendmsg4: load prog with wrong expected attach type",
+		sendmsg4_rw_asm_prog_load,
+		BPF_CGROUP_UDP6_SENDMSG,
+		BPF_CGROUP_UDP4_SENDMSG,
+		AF_INET,
+		SOCK_DGRAM,
+		NULL,
+		0,
+		NULL,
+		0,
+		NULL,
+		LOAD_REJECT,
+	},
+	{
+		"sendmsg4: attach prog with wrong attach type",
+		sendmsg4_rw_asm_prog_load,
+		BPF_CGROUP_UDP4_SENDMSG,
+		BPF_CGROUP_UDP6_SENDMSG,
+		AF_INET,
+		SOCK_DGRAM,
+		NULL,
+		0,
+		NULL,
+		0,
+		NULL,
+		ATTACH_REJECT,
+	},
+	{
+		"sendmsg4: rewrite IP & port (asm)",
+		sendmsg4_rw_asm_prog_load,
+		BPF_CGROUP_UDP4_SENDMSG,
+		BPF_CGROUP_UDP4_SENDMSG,
+		AF_INET,
+		SOCK_DGRAM,
+		SERV4_IP,
+		SERV4_PORT,
+		SERV4_REWRITE_IP,
+		SERV4_REWRITE_PORT,
+		SRC4_REWRITE_IP,
+		SUCCESS,
+	},
+	{
+		"sendmsg4: rewrite IP & port (C)",
+		sendmsg4_rw_c_prog_load,
+		BPF_CGROUP_UDP4_SENDMSG,
+		BPF_CGROUP_UDP4_SENDMSG,
+		AF_INET,
+		SOCK_DGRAM,
+		SERV4_IP,
+		SERV4_PORT,
+		SERV4_REWRITE_IP,
+		SERV4_REWRITE_PORT,
+		SRC4_REWRITE_IP,
+		SUCCESS,
+	},
+	{
+		"sendmsg4: deny call",
+		sendmsg_deny_prog_load,
+		BPF_CGROUP_UDP4_SENDMSG,
+		BPF_CGROUP_UDP4_SENDMSG,
+		AF_INET,
+		SOCK_DGRAM,
+		SERV4_IP,
+		SERV4_PORT,
+		SERV4_REWRITE_IP,
+		SERV4_REWRITE_PORT,
+		SRC4_REWRITE_IP,
+		SYSCALL_EPERM,
+	},
+	{
+		"sendmsg6: load prog with wrong expected attach type",
+		sendmsg6_rw_asm_prog_load,
+		BPF_CGROUP_UDP4_SENDMSG,
+		BPF_CGROUP_UDP6_SENDMSG,
+		AF_INET6,
+		SOCK_DGRAM,
+		NULL,
+		0,
+		NULL,
+		0,
+		NULL,
+		LOAD_REJECT,
+	},
+	{
+		"sendmsg6: attach prog with wrong attach type",
+		sendmsg6_rw_asm_prog_load,
+		BPF_CGROUP_UDP6_SENDMSG,
+		BPF_CGROUP_UDP4_SENDMSG,
+		AF_INET6,
+		SOCK_DGRAM,
+		NULL,
+		0,
+		NULL,
+		0,
+		NULL,
+		ATTACH_REJECT,
+	},
+	{
+		"sendmsg6: rewrite IP & port (asm)",
+		sendmsg6_rw_asm_prog_load,
+		BPF_CGROUP_UDP6_SENDMSG,
+		BPF_CGROUP_UDP6_SENDMSG,
+		AF_INET6,
+		SOCK_DGRAM,
+		SERV6_IP,
+		SERV6_PORT,
+		SERV6_REWRITE_IP,
+		SERV6_REWRITE_PORT,
+		SRC6_REWRITE_IP,
+		SUCCESS,
+	},
+	{
+		"sendmsg6: rewrite IP & port (C)",
+		sendmsg6_rw_c_prog_load,
+		BPF_CGROUP_UDP6_SENDMSG,
+		BPF_CGROUP_UDP6_SENDMSG,
+		AF_INET6,
+		SOCK_DGRAM,
+		SERV6_IP,
+		SERV6_PORT,
+		SERV6_REWRITE_IP,
+		SERV6_REWRITE_PORT,
+		SRC6_REWRITE_IP,
+		SUCCESS,
+	},
+	{
+		"sendmsg6: IPv4-mapped IPv6",
+		sendmsg6_rw_v4mapped_prog_load,
+		BPF_CGROUP_UDP6_SENDMSG,
+		BPF_CGROUP_UDP6_SENDMSG,
+		AF_INET6,
+		SOCK_DGRAM,
+		SERV6_IP,
+		SERV6_PORT,
+		SERV6_REWRITE_IP,
+		SERV6_REWRITE_PORT,
+		SRC6_REWRITE_IP,
+		SYSCALL_ENOTSUPP,
+	},
+	{
+		"sendmsg6: deny call",
+		sendmsg_deny_prog_load,
+		BPF_CGROUP_UDP6_SENDMSG,
+		BPF_CGROUP_UDP6_SENDMSG,
+		AF_INET6,
+		SOCK_DGRAM,
+		SERV6_IP,
+		SERV6_PORT,
+		SERV6_REWRITE_IP,
+		SERV6_REWRITE_PORT,
+		SRC6_REWRITE_IP,
+		SYSCALL_EPERM,
+	},
 };
 
 static int mk_sockaddr(int domain, const char *ip, unsigned short port,
@@ -540,6 +717,141 @@ static int connect6_prog_load(const struct sock_addr_test *test)
 	return load_path(test, CONNECT6_PROG_PATH);
 }
 
+static int sendmsg_deny_prog_load(const struct sock_addr_test *test)
+{
+	struct bpf_insn insns[] = {
+		/* return 0 */
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	return load_insns(test, insns, sizeof(insns) / sizeof(struct bpf_insn));
+}
+
+static int sendmsg4_rw_asm_prog_load(const struct sock_addr_test *test)
+{
+	struct sockaddr_in dst4_rw_addr;
+	struct in_addr src4_rw_ip;
+
+	if (inet_pton(AF_INET, SRC4_REWRITE_IP, (void *)&src4_rw_ip) != 1) {
+		log_err("Invalid IPv4: %s", SRC4_REWRITE_IP);
+		return -1;
+	}
+
+	if (mk_sockaddr(AF_INET, SERV4_REWRITE_IP, SERV4_REWRITE_PORT,
+			(struct sockaddr *)&dst4_rw_addr,
+			sizeof(dst4_rw_addr)) == -1)
+		return -1;
+
+	struct bpf_insn insns[] = {
+		BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
+
+		/* if (sk.family == AF_INET && */
+		BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
+			    offsetof(struct bpf_sock_addr, family)),
+		BPF_JMP_IMM(BPF_JNE, BPF_REG_7, AF_INET, 8),
+
+		/*     sk.type == SOCK_DGRAM)  { */
+		BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
+			    offsetof(struct bpf_sock_addr, type)),
+		BPF_JMP_IMM(BPF_JNE, BPF_REG_7, SOCK_DGRAM, 6),
+
+		/*      msg_src_ip4 = src4_rw_ip */
+		BPF_MOV32_IMM(BPF_REG_7, src4_rw_ip.s_addr),
+		BPF_STX_MEM(BPF_W, BPF_REG_6, BPF_REG_7,
+			    offsetof(struct bpf_sock_addr, msg_src_ip4)),
+
+		/*      user_ip4 = dst4_rw_addr.sin_addr */
+		BPF_MOV32_IMM(BPF_REG_7, dst4_rw_addr.sin_addr.s_addr),
+		BPF_STX_MEM(BPF_W, BPF_REG_6, BPF_REG_7,
+			    offsetof(struct bpf_sock_addr, user_ip4)),
+
+		/*      user_port = dst4_rw_addr.sin_port */
+		BPF_MOV32_IMM(BPF_REG_7, dst4_rw_addr.sin_port),
+		BPF_STX_MEM(BPF_W, BPF_REG_6, BPF_REG_7,
+			    offsetof(struct bpf_sock_addr, user_port)),
+		/* } */
+
+		/* return 1 */
+		BPF_MOV64_IMM(BPF_REG_0, 1),
+		BPF_EXIT_INSN(),
+	};
+
+	return load_insns(test, insns, sizeof(insns) / sizeof(struct bpf_insn));
+}
+
+static int sendmsg4_rw_c_prog_load(const struct sock_addr_test *test)
+{
+	return load_path(test, SENDMSG4_PROG_PATH);
+}
+
+static int sendmsg6_rw_dst_asm_prog_load(const struct sock_addr_test *test,
+					 const char *rw_dst_ip)
+{
+	struct sockaddr_in6 dst6_rw_addr;
+	struct in6_addr src6_rw_ip;
+
+	if (inet_pton(AF_INET6, SRC6_REWRITE_IP, (void *)&src6_rw_ip) != 1) {
+		log_err("Invalid IPv6: %s", SRC6_REWRITE_IP);
+		return -1;
+	}
+
+	if (mk_sockaddr(AF_INET6, rw_dst_ip, SERV6_REWRITE_PORT,
+			(struct sockaddr *)&dst6_rw_addr,
+			sizeof(dst6_rw_addr)) == -1)
+		return -1;
+
+	struct bpf_insn insns[] = {
+		BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
+
+		/* if (sk.family == AF_INET6) { */
+		BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
+			    offsetof(struct bpf_sock_addr, family)),
+		BPF_JMP_IMM(BPF_JNE, BPF_REG_7, AF_INET6, 18),
+
+#define STORE_IPV6_WORD_N(DST, SRC, N)					       \
+		BPF_MOV32_IMM(BPF_REG_7, SRC[N]),			       \
+		BPF_STX_MEM(BPF_W, BPF_REG_6, BPF_REG_7,		       \
+			    offsetof(struct bpf_sock_addr, DST[N]))
+
+#define STORE_IPV6(DST, SRC)						       \
+		STORE_IPV6_WORD_N(DST, SRC, 0),				       \
+		STORE_IPV6_WORD_N(DST, SRC, 1),				       \
+		STORE_IPV6_WORD_N(DST, SRC, 2),				       \
+		STORE_IPV6_WORD_N(DST, SRC, 3)
+
+		STORE_IPV6(msg_src_ip6, src6_rw_ip.s6_addr32),
+		STORE_IPV6(user_ip6, dst6_rw_addr.sin6_addr.s6_addr32),
+
+		/*      user_port = dst6_rw_addr.sin6_port */
+		BPF_MOV32_IMM(BPF_REG_7, dst6_rw_addr.sin6_port),
+		BPF_STX_MEM(BPF_W, BPF_REG_6, BPF_REG_7,
+			    offsetof(struct bpf_sock_addr, user_port)),
+
+		/* } */
+
+		/* return 1 */
+		BPF_MOV64_IMM(BPF_REG_0, 1),
+		BPF_EXIT_INSN(),
+	};
+
+	return load_insns(test, insns, sizeof(insns) / sizeof(struct bpf_insn));
+}
+
+static int sendmsg6_rw_asm_prog_load(const struct sock_addr_test *test)
+{
+	return sendmsg6_rw_dst_asm_prog_load(test, SERV6_REWRITE_IP);
+}
+
+static int sendmsg6_rw_v4mapped_prog_load(const struct sock_addr_test *test)
+{
+	return sendmsg6_rw_dst_asm_prog_load(test, SERV6_V4MAPPED_IP);
+}
+
+static int sendmsg6_rw_c_prog_load(const struct sock_addr_test *test)
+{
+	return load_path(test, SENDMSG6_PROG_PATH);
+}
+
 static int cmp_addr(const struct sockaddr_storage *addr1,
 		    const struct sockaddr_storage *addr2, int cmp_port)
 {
@@ -656,6 +968,135 @@ static int connect_to_server(int type, const struct sockaddr_storage *addr,
 	return fd;
 }
 
+int init_pktinfo(int domain, struct cmsghdr *cmsg)
+{
+	struct in6_pktinfo *pktinfo6;
+	struct in_pktinfo *pktinfo4;
+
+	if (domain == AF_INET) {
+		cmsg->cmsg_level = SOL_IP;
+		cmsg->cmsg_type = IP_PKTINFO;
+		cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
+		pktinfo4 = (struct in_pktinfo *)CMSG_DATA(cmsg);
+		memset(pktinfo4, 0, sizeof(struct in_pktinfo));
+		if (inet_pton(domain, SRC4_IP,
+			      (void *)&pktinfo4->ipi_spec_dst) != 1)
+			return -1;
+	} else if (domain == AF_INET6) {
+		cmsg->cmsg_level = SOL_IPV6;
+		cmsg->cmsg_type = IPV6_PKTINFO;
+		cmsg->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
+		pktinfo6 = (struct in6_pktinfo *)CMSG_DATA(cmsg);
+		memset(pktinfo6, 0, sizeof(struct in6_pktinfo));
+		if (inet_pton(domain, SRC6_IP,
+			      (void *)&pktinfo6->ipi6_addr) != 1)
+			return -1;
+	} else {
+		return -1;
+	}
+
+	return 0;
+}
+
+static int sendmsg_to_server(const struct sockaddr_storage *addr,
+			     socklen_t addr_len, int set_cmsg, int *syscall_err)
+{
+	union {
+		char buf[CMSG_SPACE(sizeof(struct in6_pktinfo))];
+		struct cmsghdr align;
+	} control6;
+	union {
+		char buf[CMSG_SPACE(sizeof(struct in_pktinfo))];
+		struct cmsghdr align;
+	} control4;
+	struct msghdr hdr;
+	struct iovec iov;
+	char data = 'a';
+	int domain;
+	int fd = -1;
+
+	domain = addr->ss_family;
+
+	if (domain != AF_INET && domain != AF_INET6) {
+		log_err("Unsupported address family");
+		goto err;
+	}
+
+	fd = socket(domain, SOCK_DGRAM, 0);
+	if (fd == -1) {
+		log_err("Failed to create client socket");
+		goto err;
+	}
+
+	memset(&iov, 0, sizeof(iov));
+	iov.iov_base = &data;
+	iov.iov_len = sizeof(data);
+
+	memset(&hdr, 0, sizeof(hdr));
+	hdr.msg_name = (void *)addr;
+	hdr.msg_namelen = addr_len;
+	hdr.msg_iov = &iov;
+	hdr.msg_iovlen = 1;
+
+	if (set_cmsg) {
+		if (domain == AF_INET) {
+			hdr.msg_control = &control4;
+			hdr.msg_controllen = sizeof(control4.buf);
+		} else if (domain == AF_INET6) {
+			hdr.msg_control = &control6;
+			hdr.msg_controllen = sizeof(control6.buf);
+		}
+		if (init_pktinfo(domain, CMSG_FIRSTHDR(&hdr))) {
+			log_err("Fail to init pktinfo");
+			goto err;
+		}
+	}
+
+	if (sendmsg(fd, &hdr, 0) != sizeof(data)) {
+		log_err("Fail to send message to server");
+		*syscall_err = errno;
+		goto err;
+	}
+
+	goto out;
+err:
+	close(fd);
+	fd = -1;
+out:
+	return fd;
+}
+
+static int recvmsg_from_client(int sockfd, struct sockaddr_storage *src_addr)
+{
+	struct timeval tv;
+	struct msghdr hdr;
+	struct iovec iov;
+	char data[64];
+	fd_set rfds;
+
+	FD_ZERO(&rfds);
+	FD_SET(sockfd, &rfds);
+
+	tv.tv_sec = 2;
+	tv.tv_usec = 0;
+
+	if (select(sockfd + 1, &rfds, NULL, NULL, &tv) <= 0 ||
+	    !FD_ISSET(sockfd, &rfds))
+		return -1;
+
+	memset(&iov, 0, sizeof(iov));
+	iov.iov_base = data;
+	iov.iov_len = sizeof(data);
+
+	memset(&hdr, 0, sizeof(hdr));
+	hdr.msg_name = src_addr;
+	hdr.msg_namelen = sizeof(struct sockaddr_storage);
+	hdr.msg_iov = &iov;
+	hdr.msg_iovlen = 1;
+
+	return recvmsg(sockfd, &hdr, 0);
+}
+
 static int init_addrs(const struct sock_addr_test *test,
 		      struct sockaddr_storage *requested_addr,
 		      struct sockaddr_storage *expected_addr,
@@ -753,6 +1194,69 @@ static int run_connect_test_case(const struct sock_addr_test *test)
 	return err;
 }
 
+static int run_sendmsg_test_case(const struct sock_addr_test *test)
+{
+	socklen_t addr_len = sizeof(struct sockaddr_storage);
+	struct sockaddr_storage expected_src_addr;
+	struct sockaddr_storage requested_addr;
+	struct sockaddr_storage expected_addr;
+	struct sockaddr_storage real_src_addr;
+	int clientfd = -1;
+	int servfd = -1;
+	int set_cmsg;
+	int err = 0;
+
+	if (test->type != SOCK_DGRAM)
+		goto err;
+
+	if (init_addrs(test, &requested_addr, &expected_addr,
+		       &expected_src_addr))
+		goto err;
+
+	/* Prepare server to sendmsg to */
+	servfd = start_server(test->type, &expected_addr, addr_len);
+	if (servfd == -1)
+		goto err;
+
+	for (set_cmsg = 0; set_cmsg <= 1; ++set_cmsg) {
+		if (clientfd >= 0)
+			close(clientfd);
+
+		clientfd = sendmsg_to_server(&requested_addr, addr_len,
+					     set_cmsg, &err);
+		if (err)
+			goto out;
+		else if (clientfd == -1)
+			goto err;
+
+		/* Try to receive message on server instead of using
+		 * getpeername(2) on client socket, to check that client's
+		 * destination address was rewritten properly, since
+		 * getpeername(2) doesn't work with unconnected datagram
+		 * sockets.
+		 *
+		 * Get source address from recvmsg(2) as well to make sure
+		 * source was rewritten properly: getsockname(2) can't be used
+		 * since socket is unconnected and source defined for one
+		 * specific packet may differ from the one used by default and
+		 * returned by getsockname(2).
+		 */
+		if (recvmsg_from_client(servfd, &real_src_addr) == -1)
+			goto err;
+
+		if (cmp_addr(&real_src_addr, &expected_src_addr, /*cmp_port*/0))
+			goto err;
+	}
+
+	goto out;
+err:
+	err = -1;
+out:
+	close(clientfd);
+	close(servfd);
+	return err;
+}
+
 static int run_test_case(int cgfd, const struct sock_addr_test *test)
 {
 	int progfd = -1;
@@ -784,10 +1288,24 @@ static int run_test_case(int cgfd, const struct sock_addr_test *test)
 	case BPF_CGROUP_INET6_CONNECT:
 		err = run_connect_test_case(test);
 		break;
+	case BPF_CGROUP_UDP4_SENDMSG:
+	case BPF_CGROUP_UDP6_SENDMSG:
+		err = run_sendmsg_test_case(test);
+		break;
 	default:
 		goto err;
 	}
 
+	if (test->expected_result == SYSCALL_EPERM && err == EPERM) {
+		err = 0; /* error was expected, reset it */
+		goto out;
+	}
+
+	if (test->expected_result == SYSCALL_ENOTSUPP && err == ENOTSUPP) {
+		err = 0; /* error was expected, reset it */
+		goto out;
+	}
+
 	if (err || test->expected_result != SUCCESS)
 		goto err;
 
-- 
2.9.5

Re: [PATCH v2 bpf-next 1/5] bpf: Hooks for sys_sendmsg

[Martin KaFai Lau]

On Tue, May 22, 2018 at 04:40:02PM -0700, Andrey Ignatov wrote:
> In addition to already existing BPF hooks for sys_bind and sys_connect,
> the patch provides new hooks for sys_sendmsg.
> 
> It leverages existing BPF program type `BPF_PROG_TYPE_CGROUP_SOCK_ADDR`
> that provides access to socket itlself (properties like family, type,
> protocol) and user-passed `struct sockaddr *` so that BPF program can
> override destination IP and port for system calls such as sendto(2) or
> sendmsg(2) and/or assign source IP to the socket.
> 
> The hooks are implemented as two new attach types:
> `BPF_CGROUP_UDP4_SENDMSG` and `BPF_CGROUP_UDP6_SENDMSG` for UDPv4 and
> UDPv6 correspondingly.
> 
> UDPv4 and UDPv6 separate attach types for same reason as sys_bind and
> sys_connect hooks, i.e. to prevent reading from / writing to e.g.
> user_ip6 fields when user passes sockaddr_in since it'd be out-of-bound.
> 
> The difference with already existing hooks is sys_sendmsg are
> implemented only for unconnected UDP.
> 
> For TCP it doesn't make sense to change user-provided `struct sockaddr *`
> at sendto(2)/sendmsg(2) time since socket either was already connected
> and has source/destination set or wasn't connected and call to
> sendto(2)/sendmsg(2) would lead to ENOTCONN anyway.
> 
> Connected UDP is already handled by sys_connect hooks that can override
> source/destination at connect time and use fast-path later, i.e. these
> hooks don't affect UDP fast-path.
> 
> Rewriting source IP is implemented differently than that in sys_connect
> hooks. When sys_sendmsg is used with unconnected UDP it doesn't work to
> just bind socket to desired local IP address since source IP can be set
> on per-packet basis by using ancillary data (cmsg(3)). So no matter if
> socket is bound or not, source IP has to be rewritten on every call to
> sys_sendmsg.
> 
> To do so two new fields are added to UAPI `struct bpf_sock_addr`;
> * `msg_src_ip4` to set source IPv4 for UDPv4;
> * `msg_src_ip6` to set source IPv6 for UDPv6.
> 
> Signed-off-by: Andrey Ignatov <rdna@fb.com>
> Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>

Re: [PATCH v2 bpf-next 1/5] bpf: Hooks for sys_sendmsg

[Daniel Borkmann]

On 05/23/2018 01:40 AM, Andrey Ignatov wrote:
[...]
> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> index ff4d4ba..a1f9ba2 100644
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -900,6 +900,7 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
>  {
>  	struct inet_sock *inet = inet_sk(sk);
>  	struct udp_sock *up = udp_sk(sk);
> +	DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name);
>  	struct flowi4 fl4_stack;
>  	struct flowi4 *fl4;
>  	int ulen = len;
> @@ -954,8 +955,7 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
>  	/*
>  	 *	Get and verify the address.
>  	 */
> -	if (msg->msg_name) {
> -		DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name);
> +	if (usin) {
>  		if (msg->msg_namelen < sizeof(*usin))
>  			return -EINVAL;
>  		if (usin->sin_family != AF_INET) {
> @@ -1009,6 +1009,22 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
>  		rcu_read_unlock();
>  	}
>  
> +	if (!connected) {
> +		err = BPF_CGROUP_RUN_PROG_UDP4_SENDMSG_LOCK(sk,
> +					    (struct sockaddr *)usin, &ipc.addr);
> +		if (err)
> +			goto out_free;
> +		if (usin) {
> +			if (usin->sin_port == 0) {
> +				/* BPF program set invalid port. Reject it. */
> +				err = -EINVAL;
> +				goto out_free;
> +			}
> +			daddr = usin->sin_addr.s_addr;
> +			dport = usin->sin_port;
> +		}
> +	}
> +
>  	saddr = ipc.addr;
>  	ipc.addr = faddr = daddr;
>  
> diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
> index 2839c1b..67c44b5 100644
> --- a/net/ipv6/udp.c
> +++ b/net/ipv6/udp.c
> @@ -1315,6 +1315,29 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
>  		fl6.saddr = np->saddr;
>  	fl6.fl6_sport = inet->inet_sport;
>  
> +	if (!connected) {
> +		err = BPF_CGROUP_RUN_PROG_UDP6_SENDMSG_LOCK(sk,
> +					   (struct sockaddr *)sin6, &fl6.saddr);
> +		if (err)
> +			goto out_no_dst;
> +		if (sin6) {
> +			if (ipv6_addr_v4mapped(&sin6->sin6_addr)) {
> +				/* BPF program rewrote IPv6-only by IPv4-mapped
> +				 * IPv6. It's currently unsupported.
> +				 */
> +				err = -ENOTSUPP;
> +				goto out_no_dst;
> +			}
> +			if (sin6->sin6_port == 0) {
> +				/* BPF program set invalid port. Reject it. */
> +				err = -EINVAL;
> +				goto out_no_dst;
> +			}
> +			fl6.fl6_dport = sin6->sin6_port;
> +			fl6.daddr = sin6->sin6_addr;
> +		}

Hmm, this extra work here and in v4 case should probably all be done under
the static key? Otherwise we'll do the extra work for checking sin6 and
setting up fl6 twice? Also, when not enabled, couldn't we run into the case
of ipv6_addr_v4mapped() as well? If I'm spotting this right, then we would
bail out though we shouldn't normally?

> +	}
> +
>  	final_p = fl6_update_dst(&fl6, opt, &final);
>  	if (final_p)
>  		connected = false;
> @@ -1394,6 +1417,7 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
>  
>  out:
>  	dst_release(dst);
> +out_no_dst:
>  	fl6_sock_release(flowlabel);
>  	txopt_put(opt_to_free);
>  	if (!err)
> 

Re: [PATCH v2 bpf-next 1/5] bpf: Hooks for sys_sendmsg

[Andrey Ignatov]

Daniel Borkmann <daniel@iogearbox.net> [Thu, 2018-05-24 18:00 -0700]:
> On 05/23/2018 01:40 AM, Andrey Ignatov wrote:
> [...]
> > diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> > index ff4d4ba..a1f9ba2 100644
> > --- a/net/ipv4/udp.c
> > +++ b/net/ipv4/udp.c
> > @@ -900,6 +900,7 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
> >  {
> >  	struct inet_sock *inet = inet_sk(sk);
> >  	struct udp_sock *up = udp_sk(sk);
> > +	DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name);
> >  	struct flowi4 fl4_stack;
> >  	struct flowi4 *fl4;
> >  	int ulen = len;
> > @@ -954,8 +955,7 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
> >  	/*
> >  	 *	Get and verify the address.
> >  	 */
> > -	if (msg->msg_name) {
> > -		DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name);
> > +	if (usin) {
> >  		if (msg->msg_namelen < sizeof(*usin))
> >  			return -EINVAL;
> >  		if (usin->sin_family != AF_INET) {
> > @@ -1009,6 +1009,22 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
> >  		rcu_read_unlock();
> >  	}
> >  
> > +	if (!connected) {
> > +		err = BPF_CGROUP_RUN_PROG_UDP4_SENDMSG_LOCK(sk,
> > +					    (struct sockaddr *)usin, &ipc.addr);
> > +		if (err)
> > +			goto out_free;
> > +		if (usin) {
> > +			if (usin->sin_port == 0) {
> > +				/* BPF program set invalid port. Reject it. */
> > +				err = -EINVAL;
> > +				goto out_free;
> > +			}
> > +			daddr = usin->sin_addr.s_addr;
> > +			dport = usin->sin_port;
> > +		}
> > +	}
> > +
> >  	saddr = ipc.addr;
> >  	ipc.addr = faddr = daddr;
> >  
> > diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
> > index 2839c1b..67c44b5 100644
> > --- a/net/ipv6/udp.c
> > +++ b/net/ipv6/udp.c
> > @@ -1315,6 +1315,29 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
> >  		fl6.saddr = np->saddr;
> >  	fl6.fl6_sport = inet->inet_sport;
> >  
> > +	if (!connected) {
> > +		err = BPF_CGROUP_RUN_PROG_UDP6_SENDMSG_LOCK(sk,
> > +					   (struct sockaddr *)sin6, &fl6.saddr);
> > +		if (err)
> > +			goto out_no_dst;
> > +		if (sin6) {
> > +			if (ipv6_addr_v4mapped(&sin6->sin6_addr)) {
> > +				/* BPF program rewrote IPv6-only by IPv4-mapped
> > +				 * IPv6. It's currently unsupported.
> > +				 */
> > +				err = -ENOTSUPP;
> > +				goto out_no_dst;
> > +			}
> > +			if (sin6->sin6_port == 0) {
> > +				/* BPF program set invalid port. Reject it. */
> > +				err = -EINVAL;
> > +				goto out_no_dst;
> > +			}
> > +			fl6.fl6_dport = sin6->sin6_port;
> > +			fl6.daddr = sin6->sin6_addr;
> > +		}
> 
> Hmm, this extra work here and in v4 case should probably all be done under
> the static key? Otherwise we'll do the extra work for checking sin6 and
> setting up fl6 twice?

Hm .. true, we can put the whole this block under static key (the main
one, since there are no others, but we can follow-up separately):

	if (cgroup_bpf_enabled && !connected) {

I'll send v3 with this change for both ipv6 and ipv4. Thanks.

As for the logic inside the `if`, I'll describe it just in case, since
some things may not be obvious.

There are two cases earlier in this function that can lead to
`connected = false`, either user specifies destination address (the 1st
`if (sin6)`) or/and user specifies ancillary data
(`if (msg->msg_controllen)`). 

Ancillary data can contain option to set source IP. So to simplify: if
user specifies source or destination we're in unconnected mode. 

Now imagine that we have connected socket and then user calls sendmsg
without setting destination (sin6 = NULL), but sets the source IP in
ancillary data at the same time. It will cause `connected = false` and
BPF prog will be run (it can e.g. override that source IP set by user),
but we have no sin6, that's why this `if (sin6)` is second time here.

On the other hand if sin6 is passed by user, it'll cause unconnected
mode as well and BPF prog has a chance to override IP and port in sin6
and in this case we have to update fl6 after BPF prog finishes. That's
why `fl6.daddr = sin6->sin6_addr;` the second time.

But I agree that work should be avoided when cgroup-bpf is disabled.

> Also, when not enabled, couldn't we run into the case
> of ipv6_addr_v4mapped() as well? If I'm spotting this right, then we would
> bail out though we shouldn't normally?

IPv4-mapped IPv6 case is handled earlier in this function and if user
passed IPv4-mapped IPv6, we don't get this far and call IPv4
udp_sendmsg() much earlier.

Same is true for port.

That's why this code wouldn't affect the logic for IPv4-mapped IPv6, but
again, you're right that we shouldn't do this extra work when cgroup-bpf
is disabled and I'll fix it.

> 
> > +	}
> > +
> >  	final_p = fl6_update_dst(&fl6, opt, &final);
> >  	if (final_p)
> >  		connected = false;
> > @@ -1394,6 +1417,7 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
> >  
> >  out:
> >  	dst_release(dst);
> > +out_no_dst:
> >  	fl6_sock_release(flowlabel);
> >  	txopt_put(opt_to_free);
> >  	if (!err)
> > 
> 

-- 
Andrey Ignatov