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authorMartin KaFai Lau <kafai@fb.com>2020-07-08 23:11:10 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2020-07-09 22:03:31 +0200
commitc9a368f1c0fbe2e3a21ebf231caeae58b18b2681 (patch)
treea447f0db6ed016bd9fe2c64692fcb01f88657102 /include
parentf3dda7a679df183e798b86e7b6ec05ab35476de3 (diff)
bpf: net: Avoid incorrect bpf_sk_reuseport_detach call
bpf_sk_reuseport_detach is currently called when sk->sk_user_data is not NULL. It is incorrect because sk->sk_user_data may not be managed by the bpf's reuseport_array. It has been reported in [1] that, the bpf_sk_reuseport_detach() which is called from udp_lib_unhash() has corrupted the sk_user_data managed by l2tp. This patch solves it by using another bit (defined as SK_USER_DATA_BPF) of the sk_user_data pointer value. It marks that a sk_user_data is managed/owned by BPF. The patch depends on a PTRMASK introduced in commit f1ff5ce2cd5e ("net, sk_msg: Clear sk_user_data pointer on clone if tagged"). [ Note: sk->sk_user_data is used by bpf's reuseport_array only when a sk is added to the bpf's reuseport_array. i.e. doing setsockopt(SO_REUSEPORT) and having "sk->sk_reuseport == 1" alone will not stop sk->sk_user_data being used by other means. ] [1]: https://lore.kernel.org/netdev/20200706121259.GA20199@katalix.com/ Fixes: 5dc4c4b7d4e8 ("bpf: Introduce BPF_MAP_TYPE_REUSEPORT_SOCKARRAY") Reported-by: James Chapman <jchapman@katalix.com> Reported-by: syzbot+9f092552ba9a5efca5df@syzkaller.appspotmail.com Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Tested-by: James Chapman <jchapman@katalix.com> Acked-by: James Chapman <jchapman@katalix.com> Link: https://lore.kernel.org/bpf/20200709061110.4019316-1-kafai@fb.com
Diffstat (limited to 'include')
-rw-r--r--include/net/sock.h3
1 files changed, 2 insertions, 1 deletions
diff --git a/include/net/sock.h b/include/net/sock.h
index 3428619faae4..1183507df95b 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -533,7 +533,8 @@ enum sk_pacing {
* be copied.
*/
#define SK_USER_DATA_NOCOPY 1UL
-#define SK_USER_DATA_PTRMASK ~(SK_USER_DATA_NOCOPY)
+#define SK_USER_DATA_BPF 2UL /* Managed by BPF */
+#define SK_USER_DATA_PTRMASK ~(SK_USER_DATA_NOCOPY | SK_USER_DATA_BPF)
/**
* sk_user_data_is_nocopy - Test if sk_user_data pointer must not be copied