From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 75C2448A2CC; Sat, 3 Oct 2026 16:35:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791045330; cv=none; b=hEBIhCsYG079BzyNd+rVKdIde1yj2i7lnIn9Dx1hiIpP+Purj0DbZSPr0HM+dT8muqMt9GDCToUE3KQhp0PL5kwpYnDvheMSTqLMJ/FLOEofyg7ZsyLeNLLIsKKT0dYT009HJX22RdNn/0/XWYIG54HwDuOvMGV7kVA8WKX9IDo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791045330; c=relaxed/simple; bh=cmvBgE8j7lEIwIHYRjNnf+zUr9OvcTqLonRqpWRcCZk=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=mzr+DAIH9n62EGxdAPEFUPCVeHBty2xk+hZTymnQZjpvzjWCEGSOztZIGRWbmJjjfkPQRGskZfuSycbVnS+19z+wINcZGnKDTXsQ56EId2NpcRWYHbUbbG/rnqEFcjBS5sdK4XV8yGQz0hgyZgxxiM0r/EP0f2Wq3D4G0kTkt6k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HJ5Hmyyu; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="HJ5Hmyyu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DF2341F0089E; Sat, 3 Oct 2026 16:35:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791045328; bh=kNAw/tP0Vwe7FDz0wtyVCYXyzGO5WEZw0f/DZkidmHw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=HJ5HmyyuYUI7mHR68tvifLIMJNUYVOqTvHHekJ/GRVUA06PTntm6PCvaWsk+GtcL/ zvj9l0bolIHMgX1XKLWHGnDE4ZutlBFjInFl3thlODchR0JzWLdGqUUpHhS/FjB7X3 xsZIKXqVAGCwzRmoHu/caqW7f8TUPNCQfuJJLmdId24ncw8iUCpACkrbpigIBrylv7 osz1369aDtL82JbRaHmsJEZrOx4PfR3ZONlWQvcWpmqw/9HJAkTubJOnNSdE4GPd/8 ZA2dQTiiO/kkEoGYYCd9xz3W9N+lC7HjklisA0XsueTtlFBNJxqRlh2QIfYsC025y9 thX7L5v4QtlEw== From: Allison Henderson To: netdev@vger.kernel.org, linux-rdma@vger.kernel.org, pabeni@redhat.com, edumazet@google.com, kuba@kernel.org, horms@kernel.org Cc: achender@kernel.org Subject: [PATCH net v3 2/2] net/rds: include the scope id in the sendmsg connection cache check Date: Sat, 3 Oct 2026 09:35:26 -0700 Message-Id: <20261003163526.250805-3-achender@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20261003163526.250805-1-achender@kernel.org> References: <20261003163526.250805-1-achender@kernel.org> Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit rds_sendmsg() reuses the connection cached in rs->rs_conn when its peer address and ToS match the request. The interface index is part of a connection's identity as well: rds_conn_create_outgoing() passes the request's scope_id down as dev_if, and rds_conn_lookup() compares c_dev_if, so sends to the same link-local address through two interfaces are two different connections. The cache-hit test never looked at it. A socket bound to a non-link-local address has rs_bound_scope_id 0, and the scope check at the top of rds_sendmsg() accepts any non-zero destination scope for such a socket. So after a send to fe80::x%ifA, a send to fe80::x%ifB hits the cached ifA connection and the datagram leaves through ifA, to whichever peer answers to that address there. Compare c_dev_if with the request's scope_id in the cache test, so that such a send takes the lookup path and finds, or creates, the ifB connection - the same key the lookup uses. With the previous patch a send without a destination carries the connected peer's scope, so the comparison is exact for it too. Fixes: 1e2b44e78eea ("rds: Enable RDS IPv6 support") Assisted-by: Claude-Code:claude-fable-5 Signed-off-by: Allison Henderson --- net/rds/send.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/rds/send.c b/net/rds/send.c index 9380b67675bd..26a937a9df6a 100644 --- a/net/rds/send.c +++ b/net/rds/send.c @@ -1342,7 +1342,8 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len) /* rds_conn_create has a spinlock that runs with IRQ off. * Caching the conn in the socket helps a lot. */ if (rs->rs_conn && ipv6_addr_equal(&rs->rs_conn->c_faddr, &daddr) && - rs->rs_tos == rs->rs_conn->c_tos) { + rs->rs_tos == rs->rs_conn->c_tos && + rs->rs_conn->c_dev_if == scope_id) { conn = rs->rs_conn; } else { conn = rds_conn_create_outgoing(sock_net(sock->sk), -- 2.25.1