diff options
| author | Martin KaFai Lau | 2022-09-29 00:04:06 -0700 |
|---|---|---|
| committer | Alexei Starovoitov | 2022-09-29 09:25:47 -0700 |
| commit | 061ff040710e9f6f043d1fa80b1b362d2845b17a (patch) | |
| tree | 44151aaed142402e16a8b6b2d356f02cd720d207 /net/ipv4/tcp_minisocks.c | |
| parent | 1e7d217faa11ac027f622124a3842aafbd0c4a42 (diff) | |
bpf: tcp: Stop bpf_setsockopt(TCP_CONGESTION) in init ops to recur itself
When a bad bpf prog '.init' calls
bpf_setsockopt(TCP_CONGESTION, "itself"), it will trigger this loop:
.init => bpf_setsockopt(tcp_cc) => .init => bpf_setsockopt(tcp_cc) ...
... => .init => bpf_setsockopt(tcp_cc).
It was prevented by the prog->active counter before but the prog->active
detection cannot be used in struct_ops as explained in the earlier
patch of the set.
In this patch, the second bpf_setsockopt(tcp_cc) is not allowed
in order to break the loop. This is done by using a bit of
an existing 1 byte hole in tcp_sock to check if there is
on-going bpf_setsockopt(TCP_CONGESTION) in this tcp_sock.
Note that this essentially limits only the first '.init' can
call bpf_setsockopt(TCP_CONGESTION) to pick a fallback cc (eg. peer
does not support ECN) and the second '.init' cannot fallback to
another cc. This applies even the second
bpf_setsockopt(TCP_CONGESTION) will not cause a loop.
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20220929070407.965581-5-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'net/ipv4/tcp_minisocks.c')
| -rw-r--r-- | net/ipv4/tcp_minisocks.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index cb95d88497ae..ddcdc2bc4c04 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -541,6 +541,7 @@ struct sock *tcp_create_openreq_child(const struct sock *sk, newtp->fastopen_req = NULL; RCU_INIT_POINTER(newtp->fastopen_rsk, NULL); + newtp->bpf_chg_cc_inprogress = 0; tcp_bpf_clone(sk, newsk); __TCP_INC_STATS(sock_net(sk), TCP_MIB_PASSIVEOPENS); |