[PATCH 5.13 516/800] skmsg: Teach sk_psock_verdict_apply() to return errors

From: Greg Kroah-Hartman
Date: Mon Jul 12 2021 - 04:39:22 EST


From: Cong Wang <cong.wang@xxxxxxxxxxxxx>

[ Upstream commit 1581a6c1c3291a8320b080f4411345f60229976d ]

Currently sk_psock_verdict_apply() is void, but it handles some
error conditions too. Its caller is impossible to learn whether
it succeeds or fails, especially sk_psock_verdict_recv().

Make it return int to indicate error cases and propagate errors
to callers properly.

Fixes: ef5659280eb1 ("bpf, sockmap: Allow skipping sk_skb parser program")
Signed-off-by: Cong Wang <cong.wang@xxxxxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Acked-by: John Fastabend <john.fastabend@xxxxxxxxx>
Acked-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20210615021342.7416-7-xiyou.wangcong@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/core/skmsg.c | 23 ++++++++++++++---------
1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/net/core/skmsg.c b/net/core/skmsg.c
index dd22ca838754..539c83a45665 100644
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c
@@ -847,7 +847,7 @@ out:
}
EXPORT_SYMBOL_GPL(sk_psock_msg_verdict);

-static void sk_psock_skb_redirect(struct sk_buff *skb)
+static int sk_psock_skb_redirect(struct sk_buff *skb)
{
struct sk_psock *psock_other;
struct sock *sk_other;
@@ -858,7 +858,7 @@ static void sk_psock_skb_redirect(struct sk_buff *skb)
*/
if (unlikely(!sk_other)) {
kfree_skb(skb);
- return;
+ return -EIO;
}
psock_other = sk_psock(sk_other);
/* This error indicates the socket is being torn down or had another
@@ -868,19 +868,20 @@ static void sk_psock_skb_redirect(struct sk_buff *skb)
if (!psock_other || sock_flag(sk_other, SOCK_DEAD)) {
skb_bpf_redirect_clear(skb);
kfree_skb(skb);
- return;
+ return -EIO;
}
spin_lock_bh(&psock_other->ingress_lock);
if (!sk_psock_test_state(psock_other, SK_PSOCK_TX_ENABLED)) {
spin_unlock_bh(&psock_other->ingress_lock);
skb_bpf_redirect_clear(skb);
kfree_skb(skb);
- return;
+ return -EIO;
}

skb_queue_tail(&psock_other->ingress_skb, skb);
schedule_work(&psock_other->work);
spin_unlock_bh(&psock_other->ingress_lock);
+ return 0;
}

static void sk_psock_tls_verdict_apply(struct sk_buff *skb, struct sock *sk, int verdict)
@@ -917,14 +918,15 @@ int sk_psock_tls_strp_read(struct sk_psock *psock, struct sk_buff *skb)
}
EXPORT_SYMBOL_GPL(sk_psock_tls_strp_read);

-static void sk_psock_verdict_apply(struct sk_psock *psock,
- struct sk_buff *skb, int verdict)
+static int sk_psock_verdict_apply(struct sk_psock *psock, struct sk_buff *skb,
+ int verdict)
{
struct sock *sk_other;
- int err = -EIO;
+ int err = 0;

switch (verdict) {
case __SK_PASS:
+ err = -EIO;
sk_other = psock->sk;
if (sock_flag(sk_other, SOCK_DEAD) ||
!sk_psock_test_state(psock, SK_PSOCK_TX_ENABLED)) {
@@ -957,13 +959,15 @@ static void sk_psock_verdict_apply(struct sk_psock *psock,
}
break;
case __SK_REDIRECT:
- sk_psock_skb_redirect(skb);
+ err = sk_psock_skb_redirect(skb);
break;
case __SK_DROP:
default:
out_free:
kfree_skb(skb);
}
+
+ return err;
}

static void sk_psock_write_space(struct sock *sk)
@@ -1130,7 +1134,8 @@ static int sk_psock_verdict_recv(read_descriptor_t *desc, struct sk_buff *skb,
ret = sk_psock_map_verd(ret, skb_bpf_redirect_fetch(skb));
skb->sk = NULL;
}
- sk_psock_verdict_apply(psock, skb, ret);
+ if (sk_psock_verdict_apply(psock, skb, ret) < 0)
+ len = 0;
out:
rcu_read_unlock();
return len;
--
2.30.2