From: John Fastabend <john.fastabend@gmail.com>
To: jakub@cloudflare.com, daniel@iogearbox.net
Cc: john.fastabend@gmail.com, bpf@vger.kernel.org,
netdev@vger.kernel.org, edumazet@google.com, ast@kernel.org,
andrii@kernel.org, will@isovalent.com
Subject: [PATCH bpf v10 01/14] bpf: sockmap, pass skb ownership through read_skb
Date: Mon, 22 May 2023 19:56:05 -0700 [thread overview]
Message-ID: <20230523025618.113937-2-john.fastabend@gmail.com> (raw)
In-Reply-To: <20230523025618.113937-1-john.fastabend@gmail.com>
The read_skb hook calls consume_skb() now, but this means that if the
recv_actor program wants to use the skb it needs to inc the ref cnt
so that the consume_skb() doesn't kfree the sk_buff.
This is problematic because in some error cases under memory pressure
we may need to linearize the sk_buff from sk_psock_skb_ingress_enqueue().
Then we get this,
skb_linearize()
__pskb_pull_tail()
pskb_expand_head()
BUG_ON(skb_shared(skb))
Because we incremented users refcnt from sk_psock_verdict_recv() we
hit the bug on with refcnt > 1 and trip it.
To fix lets simply pass ownership of the sk_buff through the skb_read
call. Then we can drop the consume from read_skb handlers and assume
the verdict recv does any required kfree.
Bug found while testing in our CI which runs in VMs that hit memory
constraints rather regularly. William tested TCP read_skb handlers.
[ 106.536188] ------------[ cut here ]------------
[ 106.536197] kernel BUG at net/core/skbuff.c:1693!
[ 106.536479] invalid opcode: 0000 [#1] PREEMPT SMP PTI
[ 106.536726] CPU: 3 PID: 1495 Comm: curl Not tainted 5.19.0-rc5 #1
[ 106.537023] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ArchLinux 1.16.0-1 04/01/2014
[ 106.537467] RIP: 0010:pskb_expand_head+0x269/0x330
[ 106.538585] RSP: 0018:ffffc90000138b68 EFLAGS: 00010202
[ 106.538839] RAX: 000000000000003f RBX: ffff8881048940e8 RCX: 0000000000000a20
[ 106.539186] RDX: 0000000000000002 RSI: 0000000000000000 RDI: ffff8881048940e8
[ 106.539529] RBP: ffffc90000138be8 R08: 00000000e161fd1a R09: 0000000000000000
[ 106.539877] R10: 0000000000000018 R11: 0000000000000000 R12: ffff8881048940e8
[ 106.540222] R13: 0000000000000003 R14: 0000000000000000 R15: ffff8881048940e8
[ 106.540568] FS: 00007f277dde9f00(0000) GS:ffff88813bd80000(0000) knlGS:0000000000000000
[ 106.540954] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 106.541227] CR2: 00007f277eeede64 CR3: 000000000ad3e000 CR4: 00000000000006e0
[ 106.541569] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 106.541915] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 106.542255] Call Trace:
[ 106.542383] <IRQ>
[ 106.542487] __pskb_pull_tail+0x4b/0x3e0
[ 106.542681] skb_ensure_writable+0x85/0xa0
[ 106.542882] sk_skb_pull_data+0x18/0x20
[ 106.543084] bpf_prog_b517a65a242018b0_bpf_skskb_http_verdict+0x3a9/0x4aa9
[ 106.543536] ? migrate_disable+0x66/0x80
[ 106.543871] sk_psock_verdict_recv+0xe2/0x310
[ 106.544258] ? sk_psock_write_space+0x1f0/0x1f0
[ 106.544561] tcp_read_skb+0x7b/0x120
[ 106.544740] tcp_data_queue+0x904/0xee0
[ 106.544931] tcp_rcv_established+0x212/0x7c0
[ 106.545142] tcp_v4_do_rcv+0x174/0x2a0
[ 106.545326] tcp_v4_rcv+0xe70/0xf60
[ 106.545500] ip_protocol_deliver_rcu+0x48/0x290
[ 106.545744] ip_local_deliver_finish+0xa7/0x150
Fixes: 04919bed948dc ("tcp: Introduce tcp_read_skb()")
Reported-by: William Findlay <will@isovalent.com>
Tested-by: William Findlay <will@isovalent.com>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
---
net/core/skmsg.c | 2 --
net/ipv4/tcp.c | 1 -
net/ipv4/udp.c | 7 ++-----
net/unix/af_unix.c | 7 ++-----
net/vmw_vsock/virtio_transport_common.c | 5 +----
5 files changed, 5 insertions(+), 17 deletions(-)
diff --git a/net/core/skmsg.c b/net/core/skmsg.c
index f81883759d38..4a3dc8d27295 100644
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c
@@ -1183,8 +1183,6 @@ static int sk_psock_verdict_recv(struct sock *sk, struct sk_buff *skb)
int ret = __SK_DROP;
int len = skb->len;
- skb_get(skb);
-
rcu_read_lock();
psock = sk_psock(sk);
if (unlikely(!psock)) {
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 4d6392c16b7a..e914e3446377 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1773,7 +1773,6 @@ int tcp_read_skb(struct sock *sk, skb_read_actor_t recv_actor)
WARN_ON_ONCE(!skb_set_owner_sk_safe(skb, sk));
tcp_flags = TCP_SKB_CB(skb)->tcp_flags;
used = recv_actor(sk, skb);
- consume_skb(skb);
if (used < 0) {
if (!copied)
copied = used;
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index aa32afd871ee..9482def1f310 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1818,7 +1818,7 @@ EXPORT_SYMBOL(__skb_recv_udp);
int udp_read_skb(struct sock *sk, skb_read_actor_t recv_actor)
{
struct sk_buff *skb;
- int err, copied;
+ int err;
try_again:
skb = skb_recv_udp(sk, MSG_DONTWAIT, &err);
@@ -1837,10 +1837,7 @@ int udp_read_skb(struct sock *sk, skb_read_actor_t recv_actor)
}
WARN_ON_ONCE(!skb_set_owner_sk_safe(skb, sk));
- copied = recv_actor(sk, skb);
- kfree_skb(skb);
-
- return copied;
+ return recv_actor(sk, skb);
}
EXPORT_SYMBOL(udp_read_skb);
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index cc695c9f09ec..e7728b57a8c7 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2553,7 +2553,7 @@ static int unix_read_skb(struct sock *sk, skb_read_actor_t recv_actor)
{
struct unix_sock *u = unix_sk(sk);
struct sk_buff *skb;
- int err, copied;
+ int err;
mutex_lock(&u->iolock);
skb = skb_recv_datagram(sk, MSG_DONTWAIT, &err);
@@ -2561,10 +2561,7 @@ static int unix_read_skb(struct sock *sk, skb_read_actor_t recv_actor)
if (!skb)
return err;
- copied = recv_actor(sk, skb);
- kfree_skb(skb);
-
- return copied;
+ return recv_actor(sk, skb);
}
/*
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index e4878551f140..b769fc258931 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -1441,7 +1441,6 @@ int virtio_transport_read_skb(struct vsock_sock *vsk, skb_read_actor_t recv_acto
struct sock *sk = sk_vsock(vsk);
struct sk_buff *skb;
int off = 0;
- int copied;
int err;
spin_lock_bh(&vvs->rx_lock);
@@ -1454,9 +1453,7 @@ int virtio_transport_read_skb(struct vsock_sock *vsk, skb_read_actor_t recv_acto
if (!skb)
return err;
- copied = recv_actor(sk, skb);
- kfree_skb(skb);
- return copied;
+ return recv_actor(sk, skb);
}
EXPORT_SYMBOL_GPL(virtio_transport_read_skb);
--
2.33.0
next prev parent reply other threads:[~2023-05-23 2:56 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-23 2:56 [PATCH bpf v10 00/14] bpf sockmap fixes John Fastabend
2023-05-23 2:56 ` John Fastabend [this message]
2023-05-23 2:56 ` [PATCH bpf v10 02/14] bpf: sockmap, convert schedule_work into delayed_work John Fastabend
2023-05-23 2:56 ` [PATCH bpf v10 03/14] bpf: sockmap, reschedule is now done through backlog John Fastabend
2023-05-23 2:56 ` [PATCH bpf v10 04/14] bpf: sockmap, improved check for empty queue John Fastabend
2023-05-23 7:35 ` Jakub Sitnicki
2023-05-23 2:56 ` [PATCH bpf v10 05/14] bpf: sockmap, handle fin correctly John Fastabend
2023-05-23 2:56 ` [PATCH bpf v10 06/14] bpf: sockmap, TCP data stall on recv before accept John Fastabend
2023-05-23 2:56 ` [PATCH bpf v10 07/14] bpf: sockmap, wake up polling after data copy John Fastabend
2023-05-30 6:30 ` Eric Dumazet
2023-05-30 18:34 ` John Fastabend
2023-05-30 18:43 ` John Fastabend
2023-05-30 18:51 ` Eric Dumazet
2023-05-23 2:56 ` [PATCH bpf v10 08/14] bpf: sockmap, incorrectly handling copied_seq John Fastabend
2023-05-23 9:09 ` Jakub Sitnicki
2023-05-23 2:56 ` [PATCH bpf v10 09/14] bpf: sockmap, pull socket helpers out of listen test for general use John Fastabend
2023-05-23 2:56 ` [PATCH bpf v10 10/14] bpf: sockmap, build helper to create connected socket pair John Fastabend
2023-05-23 9:23 ` Jakub Sitnicki
2023-05-23 2:56 ` [PATCH bpf v10 11/14] bpf: sockmap, test shutdown() correctly exits epoll and recv()=0 John Fastabend
2023-05-23 9:41 ` Jakub Sitnicki
2023-05-23 2:56 ` [PATCH bpf v10 12/14] bpf: sockmap, test FIONREAD returns correct bytes in rx buffer John Fastabend
2023-05-23 2:56 ` [PATCH bpf v10 13/14] bpf: sockmap, test FIONREAD returns correct bytes in rx buffer with drops John Fastabend
2023-05-23 2:56 ` [PATCH bpf v10 14/14] bpf: sockmap, test progs verifier error with latest clang John Fastabend
2023-05-23 10:00 ` Jakub Sitnicki
2023-05-23 14:31 ` [PATCH bpf v10 00/14] bpf sockmap fixes Daniel Borkmann
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20230523025618.113937-2-john.fastabend@gmail.com \
--to=john.fastabend@gmail.com \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=edumazet@google.com \
--cc=jakub@cloudflare.com \
--cc=netdev@vger.kernel.org \
--cc=will@isovalent.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.