netdev - [PATCH bpf-next 2/5] bpf: Move the "cdg" tcp-cc check to the common sol_tcp

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20220922225629.3056949-1-kafai@fb.com>
Date:   Thu, 22 Sep 2022 15:56:29 -0700
From:   Martin KaFai Lau <kafai@...com>
To:     <bpf@...r.kernel.org>
CC:     Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andrii@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>, <kernel-team@...com>,
        <netdev@...r.kernel.org>, Martin KaFai Lau <martin.lau@...nel.org>
Subject: [PATCH bpf-next 2/5] bpf: Move the "cdg" tcp-cc check to the common sol_tcp_sockopt()

From: Martin KaFai Lau <martin.lau@...nel.org>

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 need
to expose _bpf_setsockopt() for the bpf_tcp_ca to use and it
requires the "cdg" check.

Signed-off-by: Martin KaFai Lau <martin.lau@...nel.org>
---
 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