[PATCH 5.15 262/731] bpf, sockmap: Fix missing BPF_F_INGRESS flag when using apply_bytes

Greg Kroah-Hartman
2022-12-28T15:02:05Z

From: Pengcheng Yang <yangpc@wangsu.com>

[ Upstream commit a351d6087bf7d3d8440d58d3bf244ec64b89394a ]

When redirecting, we use sk_msg_to_ingress() to get the BPF_F_INGRESS
flag from the msg->flags. If apply_bytes is used and it is larger than
the current data being processed, sk_psock_msg_verdict() will not be
called when sendmsg() is called again. At this time, the msg->flags is 0,
and we lost the BPF_F_INGRESS flag.

So we need to save the BPF_F_INGRESS flag in sk_psock and use it when
redirection.

Fixes: 8934ce2fd081 ("bpf: sockmap redirect ingress support")
Signed-off-by: Pengcheng Yang <yangpc@wangsu.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/1669718441-2654-3-git-send-email-yangpc@wangsu.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/skmsg.h | 1 +
include/net/tcp.h | 4 ++--
net/core/skmsg.c | 9 ++++++---
net/ipv4/tcp_bpf.c | 11 ++++++-----
net/tls/tls_sw.c | 6 ++++--
5 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h
index ba015a77238a..6e18ca234f81 100644
--- a/include/linux/skmsg.h
+++ b/include/linux/skmsg.h
@@ -83,6 +83,7 @@ struct sk_psock {
u32 apply_bytes;
u32 cork_bytes;
u32 eval;
+ bool redir_ingress; /* undefined if sk_redir is null */
struct sk_msg *cork;
struct sk_psock_progs progs;
#if IS_ENABLED(CONFIG_BPF_STREAM_PARSER)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 81ef95dc27ba..fdac6913b6c8 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2243,8 +2243,8 @@ int tcp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore);
void tcp_bpf_clone(const struct sock *sk, struct sock *newsk);
#endif /* CONFIG_BPF_SYSCALL */

-int tcp_bpf_sendmsg_redir(struct sock *sk, struct sk_msg *msg, u32 bytes,
- int flags);
+int tcp_bpf_sendmsg_redir(struct sock *sk, bool ingress,
+ struct sk_msg *msg, u32 bytes, int flags);
#endif /* CONFIG_NET_SOCK_MSG */

#if !defined(CONFIG_BPF_SYSCALL) || !defined(CONFIG_NET_SOCK_MSG)
diff --git a/net/core/skmsg.c b/net/core/skmsg.c
index f562f7e2bdc7..dc9b93d8f0d3 100644
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c
@@ -880,13 +880,16 @@ int sk_psock_msg_verdict(struct sock *sk, struct sk_psock *psock,
ret = sk_psock_map_verd(ret, msg->sk_redir);
psock->apply_bytes = msg->apply_bytes;
if (ret == __SK_REDIRECT) {
- if (psock->sk_redir)
+ if (psock->sk_redir) {
sock_put(psock->sk_redir);
- psock->sk_redir = msg->sk_redir;
- if (!psock->sk_redir) {
+ psock->sk_redir = NULL;
+ }
+ if (!msg->sk_redir) {
ret = __SK_DROP;
goto out;
}
+ psock->redir_ingress = sk_msg_to_ingress(msg);
+ psock->sk_redir = msg->sk_redir;
sock_hold(psock->sk_redir);
}
out:
diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index a38db402994d..2db868ca32af 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -131,10 +131,9 @@ static int tcp_bpf_push_locked(struct sock *sk, struct sk_msg *msg,
return ret;
}

-int tcp_bpf_sendmsg_redir(struct sock *sk, struct sk_msg *msg,
- u32 bytes, int flags)
+int tcp_bpf_sendmsg_redir(struct sock *sk, bool ingress,
+ struct sk_msg *msg, u32 bytes, int flags)
{
- bool ingress = sk_msg_to_ingress(msg);
struct sk_psock *psock = sk_psock_get(sk);
int ret;

@@ -277,7 +276,7 @@ static int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock,
struct sk_msg *msg, int *copied, int flags)
{
- bool cork = false, enospc = sk_msg_full(msg);
+ bool cork = false, enospc = sk_msg_full(msg), redir_ingress;
struct sock *sk_redir;
u32 tosend, origsize, sent, delta = 0;
u32 eval;
@@ -323,6 +322,7 @@ static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock,
sk_msg_apply_bytes(psock, tosend);
break;
case __SK_REDIRECT:
+ redir_ingress = psock->redir_ingress;
sk_redir = psock->sk_redir;
sk_msg_apply_bytes(psock, tosend);
if (!psock->apply_bytes) {
@@ -339,7 +339,8 @@ static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock,
release_sock(sk);

origsize = msg->sg.size;
- ret = tcp_bpf_sendmsg_redir(sk_redir, msg, tosend, flags);
+ ret = tcp_bpf_sendmsg_redir(sk_redir, redir_ingress,
+ msg, tosend, flags);
sent = origsize - msg->sg.size;

if (eval == __SK_REDIRECT)
diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index 794ef3b3d7d4..c0fea678abb1 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -801,7 +801,7 @@ static int bpf_exec_tx_verdict(struct sk_msg *msg, struct sock *sk,
struct sk_psock *psock;
struct sock *sk_redir;
struct tls_rec *rec;
- bool enospc, policy;
+ bool enospc, policy, redir_ingress;
int err = 0, send;
u32 delta = 0;

@@ -846,6 +846,7 @@ static int bpf_exec_tx_verdict(struct sk_msg *msg, struct sock *sk,
}
break;
case __SK_REDIRECT:
+ redir_ingress = psock->redir_ingress;
sk_redir = psock->sk_redir;
memcpy(&msg_redir, msg, sizeof(*msg));
if (msg->apply_bytes < send)
@@ -855,7 +856,8 @@ static int bpf_exec_tx_verdict(struct sk_msg *msg, struct sock *sk,
sk_msg_return_zero(sk, msg, send);
msg->sg.size -= send;
release_sock(sk);
- err = tcp_bpf_sendmsg_redir(sk_redir, &msg_redir, send, flags);
+ err = tcp_bpf_sendmsg_redir(sk_redir, redir_ingress,
+ &msg_redir, send, flags);
lock_sock(sk);
if (err < 0) {
*copied -= sk_msg_free_nocharge(sk, &msg_redir);
--
2.35.1