5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Zijian Zhang zijianzhang@bytedance.com
[ Upstream commit d888b7af7c149c115dd6ac772cc11c375da3e17c ]
When we do sk_psock_verdict_apply->sk_psock_skb_ingress, an sk_msg will be created out of the skb, and the rmem accounting of the sk_msg will be handled by the skb.
For skmsgs in __SK_REDIRECT case of tcp_bpf_send_verdict, when redirecting to the ingress of a socket, although we sk_rmem_schedule and add sk_msg to the ingress_msg of sk_redir, we do not update sk_rmem_alloc. As a result, except for the global memory limit, the rmem of sk_redir is nearly unlimited. Thus, add sk_rmem_alloc related logic to limit the recv buffer.
Since the function sk_msg_recvmsg and __sk_psock_purge_ingress_msg are used in these two paths. We use "msg->skb" to test whether the sk_msg is skb backed up. If it's not, we shall do the memory accounting explicitly.
Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface") Signed-off-by: Zijian Zhang zijianzhang@bytedance.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Reviewed-by: John Fastabend john.fastabend@gmail.com Link: https://lore.kernel.org/bpf/20241210012039.1669389-3-zijianzhang@bytedance.c... Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/skmsg.h | 11 ++++++++--- net/core/skmsg.c | 6 +++++- net/ipv4/tcp_bpf.c | 4 +++- 3 files changed, 16 insertions(+), 5 deletions(-)
diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h index 422b391d931f..5d3e4d4d9438 100644 --- a/include/linux/skmsg.h +++ b/include/linux/skmsg.h @@ -313,17 +313,22 @@ static inline void sock_drop(struct sock *sk, struct sk_buff *skb) kfree_skb(skb); }
-static inline void sk_psock_queue_msg(struct sk_psock *psock, +static inline bool sk_psock_queue_msg(struct sk_psock *psock, struct sk_msg *msg) { + bool ret; + spin_lock_bh(&psock->ingress_lock); - if (sk_psock_test_state(psock, SK_PSOCK_TX_ENABLED)) + if (sk_psock_test_state(psock, SK_PSOCK_TX_ENABLED)) { list_add_tail(&msg->list, &psock->ingress_msg); - else { + ret = true; + } else { sk_msg_free(psock->sk, msg); kfree(msg); + ret = false; } spin_unlock_bh(&psock->ingress_lock); + return ret; }
static inline struct sk_msg *sk_psock_dequeue_msg(struct sk_psock *psock) diff --git a/net/core/skmsg.c b/net/core/skmsg.c index f8563d4da0b1..a5947aa55983 100644 --- a/net/core/skmsg.c +++ b/net/core/skmsg.c @@ -445,8 +445,10 @@ int sk_msg_recvmsg(struct sock *sk, struct sk_psock *psock, struct msghdr *msg, if (likely(!peek)) { sge->offset += copy; sge->length -= copy; - if (!msg_rx->skb) + if (!msg_rx->skb) { sk_mem_uncharge(sk, copy); + atomic_sub(copy, &sk->sk_rmem_alloc); + } msg_rx->sg.size -= copy;
if (!sge->length) { @@ -761,6 +763,8 @@ static void __sk_psock_purge_ingress_msg(struct sk_psock *psock)
list_for_each_entry_safe(msg, tmp, &psock->ingress_msg, list) { list_del(&msg->list); + if (!msg->skb) + atomic_sub(msg->sg.size, &psock->sk->sk_rmem_alloc); sk_msg_free(psock->sk, msg); kfree(msg); } diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c index dc1291827381..9e24542251b1 100644 --- a/net/ipv4/tcp_bpf.c +++ b/net/ipv4/tcp_bpf.c @@ -38,6 +38,7 @@ static int bpf_tcp_ingress(struct sock *sk, struct sk_psock *psock, }
sk_mem_charge(sk, size); + atomic_add(size, &sk->sk_rmem_alloc); sk_msg_xfer(tmp, msg, i, size); copied += size; if (sge->length) @@ -56,7 +57,8 @@ static int bpf_tcp_ingress(struct sock *sk, struct sk_psock *psock,
if (!ret) { msg->sg.start = i; - sk_psock_queue_msg(psock, tmp); + if (!sk_psock_queue_msg(psock, tmp)) + atomic_sub(copied, &sk->sk_rmem_alloc); sk_psock_data_ready(sk, psock); } else { sk_msg_free(sk, tmp);