From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 CF33428F520; Fri, 9 May 2025 10:26:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746786387; cv=none; b=OyGksnzZ8xRZMuyByP26YRAs9GLFl1sn0j6Vo1kPrKT0vnCjnqhDSmPW+VuF3rZw2RUEOXPx8LbS30KGkw7PBnqPpgPQJnzjZdNeM4Lt1LKv6FTqHj7w+9vlQiSE68hjDwDRwzCpzXn+dHJt3G6258ggQFoTUMB/g9QNpLDu0YE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746786387; c=relaxed/simple; bh=XtYAn9qxMv6rK3q0zBvwCKauIZoqUJCYXQhXC/1IcFM=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=RRgl/Q5SfzBF0kOpz5fT4GLfldDjR7WiGyuCvy+jP9Vl2PcaHXcjq2XD1E+sttdJSjInG21mPdHLR4t/hQZJIcrqnLkmlcs3hNe/F2oe1Y8jmKxt/TIWSavAWkcpEXZC5YVIlLu9L9fE098aYsish8KbCP2GWoiAtuWZzO+Gzn0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nS0nppIm; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="nS0nppIm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EE512C4CEE9; Fri, 9 May 2025 10:26:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746786387; bh=XtYAn9qxMv6rK3q0zBvwCKauIZoqUJCYXQhXC/1IcFM=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=nS0nppImxSVITjGKUFHL/HFCSEU2yLsr7sPnSCzwevQeL3IESIxm1XdI3Ra0p7hfG 9cZhKns1Q5Ca4BinkAkD9cPZOMzuPPffkJFTiUN6qvUx+pUA+5NpdHaRN8WbioH0nU OlBUFBahfc6A2n5zF/ZOMSmEH91hqD1bR5gGm/6Thx4cUC+2mShiooJ+4eClKcs3fv zQOlV15CT9xZrDUgL8BL+0L4ArJaxUwprD+JEXyw1no3WG82ovnhpBmzVqEOM3LtZw a9bgqI5sUvTiIJgNQjp0bYEeShxUme32Ux6F7/jnMpX/RTtoEE368IGe8lIc5dCbAC Q56slUqnLfRyg== From: Christian Brauner Date: Fri, 09 May 2025 12:25:39 +0200 Subject: [PATCH v5 7/9] coredump: validate socket name as it is written Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20250509-work-coredump-socket-v5-7-23c5b14df1bc@kernel.org> References: <20250509-work-coredump-socket-v5-0-23c5b14df1bc@kernel.org> In-Reply-To: <20250509-work-coredump-socket-v5-0-23c5b14df1bc@kernel.org> To: linux-fsdevel@vger.kernel.org, Jann Horn , Daniel Borkmann , Kuniyuki Iwashima Cc: Eric Dumazet , Oleg Nesterov , "David S. Miller" , Alexander Viro , Daan De Meyer , David Rheinsberg , Jakub Kicinski , Jan Kara , Lennart Poettering , Luca Boccassi , Mike Yuan , Paolo Abeni , Simon Horman , =?utf-8?q?Zbigniew_J=C4=99drzejewski-Szmek?= , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-security-module@vger.kernel.org, Christian Brauner , Alexander Mikhalitsyn X-Mailer: b4 0.15-dev-c25d1 X-Developer-Signature: v=1; a=openpgp-sha256; l=1280; i=brauner@kernel.org; h=from:subject:message-id; bh=XtYAn9qxMv6rK3q0zBvwCKauIZoqUJCYXQhXC/1IcFM=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWTI3tBqXzpXddNFvjkbaotuaTbIzJm9NOTg4tKVj5jzR JS3ssdv7yhlYRDjYpAVU2RxaDcJl1vOU7HZKFMDZg4rE8gQBi5OAZhI4wJGhsPTFqw8fmJ5Aue3 N71Wov3Op296p13jl14418VXts9Ik4fhn6HAy+TrSnN3WV25+rGY8+nqX6+/+F//YeZXpvlkclr JVkYA X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 In contrast to other parameters written into /proc/sys/kernel/core_pattern that never fail we can validate enabling the new AF_UNIX support. This is obviously racy as hell but it's always been that way. Signed-off-by: Christian Brauner --- fs/coredump.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/fs/coredump.c b/fs/coredump.c index fa50a681b225..19e776769b21 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -1254,10 +1254,21 @@ void validate_coredump_safety(void) static int proc_dostring_coredump(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { - int error = proc_dostring(table, write, buffer, lenp, ppos); + int error; + ssize_t retval; + char old_core_pattern[CORENAME_MAX_SIZE]; - if (!error) - validate_coredump_safety(); + retval = strscpy(old_core_pattern, core_pattern, CORENAME_MAX_SIZE); + + error = proc_dostring(table, write, buffer, lenp, ppos); + if (error) + return error; + if (core_pattern[0] == '@' && strcmp(core_pattern, "@linuxafsk/coredump.socket")) { + strscpy(core_pattern, old_core_pattern, retval + 1); + return -EINVAL; + } + + validate_coredump_safety(); return error; } -- 2.47.2