netdev - [PATCH bpf 1/3] bpf, sockmap: Fix update element with same

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 for Android: free password hash cracker in your pocket

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

Message-Id: <20241202-sockmap-replace-v1-1-1e88579e7bd5@rbox.co>
Date: Mon, 02 Dec 2024 12:29:23 +0100
From: Michal Luczaj <mhal@...x.co>
To: Andrii Nakryiko <andrii@...nel.org>, 
 Eduard Zingerman <eddyz87@...il.com>, Mykola Lysenko <mykolal@...com>, 
 Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, 
 Martin KaFai Lau <martin.lau@...ux.dev>, Song Liu <song@...nel.org>, 
 Yonghong Song <yonghong.song@...ux.dev>, 
 John Fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>, 
 Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, 
 Jiri Olsa <jolsa@...nel.org>, Shuah Khan <shuah@...nel.org>, 
 Jakub Sitnicki <jakub@...udflare.com>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Simon Horman <horms@...nel.org>
Cc: bpf@...r.kernel.org, linux-kselftest@...r.kernel.org, 
 netdev@...r.kernel.org, Michal Luczaj <mhal@...x.co>
Subject: [PATCH bpf 1/3] bpf, sockmap: Fix update element with same

Consider a sockmap entry being updated with the same socket:

	osk = stab->sks[idx];
	sock_map_add_link(psock, link, map, &stab->sks[idx]);
	stab->sks[idx] = sk;
	if (osk)
		sock_map_unref(osk, &stab->sks[idx]);

Due to sock_map_unref(), which invokes sock_map_del_link(), all the psock's
links for stab->sks[idx] are torn:

	list_for_each_entry_safe(link, tmp, &psock->link, list) {
		if (link->link_raw == link_raw) {
			...
			list_del(&link->list);
			sk_psock_free_link(link);
		}
	}

And that includes the new link sock_map_add_link() added just before the
unref.

This results in a sockmap holding a socket, but without the respective
link. This in turn means that close(sock) won't trigger the cleanup, i.e. a
closed socket will not be automatically removed from the sockmap.

Stop tearing the links when a matching link_raw is found.

Signed-off-by: Michal Luczaj <mhal@...x.co>
---
 net/core/sock_map.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index 78347d7d25ef31525f8ec0a755a18e5793ad92c0..20b348b1964a10a1b0bfbe1a90a4a4cd99715b81 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -159,6 +159,7 @@ static void sock_map_del_link(struct sock *sk,
 				verdict_stop = true;
 			list_del(&link->list);
 			sk_psock_free_link(link);
+			break;
 		}
 	}
 	spin_unlock_bh(&psock->link_lock);

-- 
2.46.2