From: Martin KaFai Lau <martin.lau@xxxxxxxxxx>
The check on the tcp-cc, "cdg", is done in the bpf_sk_setsockopt which is
used by the bpf_tcp_ca, bpf_lsm, cg_sockopt, and tcp_iter hooks.
However, it is not done for cg sock_ddr, cg sockops, and some of
the bpf_lsm_cgroup hooks.
The tcp-cc "cdg" should have very limited usage. This patch is to
move the "cdg" check to the common sol_tcp_sockopt() so that all
hooks have a consistent behavior. The motivation to make
this check consistent now is because the latter patch will
refactor the bpf_setsockopt(TCP_CONGESTION) into another function,
so it is better to take this chance to refactor this piece
also.
Signed-off-by: Martin KaFai Lau <martin.lau@xxxxxxxxxx>
---
net/core/filter.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index 2fd9449026aa..f4cea3ff994a 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5127,6 +5127,13 @@ static int sol_tcp_sockopt(struct sock *sk, int optname,
case TCP_CONGESTION:
if (*optlen < 2)
return -EINVAL;
+ /* "cdg" is the only cc that alloc a ptr
+ * in inet_csk_ca area. The bpf-tcp-cc may
+ * overwrite this ptr after switching to cdg.
+ */
+ if (!getopt && *optlen >= sizeof("cdg") - 1 &&
+ !strncmp("cdg", optval, *optlen))
+ return -ENOTSUPP;
break;
case TCP_SAVED_SYN:
if (*optlen < 1)
@@ -5285,12 +5292,6 @@ static int _bpf_getsockopt(struct sock *sk, int level, int optname,
BPF_CALL_5(bpf_sk_setsockopt, struct sock *, sk, int, level,
int, optname, char *, optval, int, optlen)
{
- if (level == SOL_TCP && optname == TCP_CONGESTION) {
- if (optlen >= sizeof("cdg") - 1 &&
- !strncmp("cdg", optval, optlen))
- return -ENOTSUPP;
- }
-
return _bpf_setsockopt(sk, level, optname, optval, optlen);
}
--
2.30.2
