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 E4BB725A2B8; Mon, 12 May 2025 08:56:18 +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=1747040180; cv=none; b=PAmKQiFmKZ6FidXRWagYomZxk5Ptd6Rmi+Tspy6RKPBzX+hxNZTltkieEmvnqVtPh9Xgy9tbKn/BFLqvJ0s62tE46r0qby/Ge++THoSQnHB6JPijhFy+dUb437Hb6t1/tKuW47cFHPEN/EUsSGhJRJmLKymJViBPJ/B0XQTxt3U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747040180; c=relaxed/simple; bh=0BiGaI9QZtmJlstEuxiCKxHauy4PjCyPjPux0hQjYQA=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=docWvxaoiBKN8y8PRo9QGlgCaudBGpDe3uzQxsahN4nSCha5j3y00ImyMJy4OWb3wof3stfXsrIhTYiGtiT37QMrbXR63s1ln9/wT5C518QUunB2LqqQm7Gg8Zx3XIbN8Vt3vbIiHrE4FnbFbDhnVn6P+dh0Wu4hGQO33eEf5sw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EdQtyeyb; 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="EdQtyeyb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 643A8C4CEE9; Mon, 12 May 2025 08:56:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747040178; bh=0BiGaI9QZtmJlstEuxiCKxHauy4PjCyPjPux0hQjYQA=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=EdQtyeybwNHIadd4alM80IN3dI8TfX7rI1MrguNmxaj5Gor+BOXgdcy1FHi/3P9pg rD2tdO+ANB6qHN7uhilP1UwkltKg1W3wAvEfzoDLWLcNFDb1iPrkbyACz5sIW0DhQy 7on/P6ht/CrIzuh0UiU9fNYRTQ+dG9aqj0+tvX7a6c3WFzMzeKLMMEF925wXU09HNc 1wBpmaEnqjsSX2s+AZSJU0JpspMwVh3T92phzQGB2AoVuw6W8/WeJ8BFvy1mZhBouv TX+Y1BBqcA7AKWjGT0GOPfyEu7yfWzLxKZgqbCFhJ0iaZNoxAlgLB7EU8jYyvM433B n7aEnMV9ADBQw== From: Christian Brauner Date: Mon, 12 May 2025 10:55:26 +0200 Subject: [PATCH v6 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: <20250512-work-coredump-socket-v6-7-c51bc3450727@kernel.org> References: <20250512-work-coredump-socket-v6-0-c51bc3450727@kernel.org> In-Reply-To: <20250512-work-coredump-socket-v6-0-c51bc3450727@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=1535; i=brauner@kernel.org; h=from:subject:message-id; bh=0BiGaI9QZtmJlstEuxiCKxHauy4PjCyPjPux0hQjYQA=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWQobm9PlXhpHxhTyMm1S3/G9DfizEfMC01542d+Fytlb GiasfhRRykLgxgXg6yYIotDu0m43HKeis1GmRowc1iZQIYwcHEKwETuHWf4X9s90Y9VMnpyy/nI PgURru8RxzpXByRzLhd1aJVrTXdiY/gr+Env2/IVsw/9jVHIn255fPZCGaEDtbM97h/tXhPLEXC OHQA= 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 | 29 ++++++++++++++++++++++++++--- 1 file changed, 26 insertions(+), 3 deletions(-) diff --git a/fs/coredump.c b/fs/coredump.c index deee52bff6bc..5b9d2e063f8f 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -1242,13 +1242,36 @@ void validate_coredump_safety(void) } } +static inline bool check_coredump_socket_address(void) +{ + if (core_pattern[0] != '@') + return true; + + /* Leave enough space for the socket cookie. */ + if (strcspn(core_pattern, " ") >= (UNIX_PATH_MAX - sizeof(u64))) + return false; + + return true; +} + 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]; + + retval = strscpy(old_core_pattern, core_pattern, CORENAME_MAX_SIZE); + + error = proc_dostring(table, write, buffer, lenp, ppos); + if (error) + return error; + if (!check_coredump_socket_address()) { + strscpy(core_pattern, old_core_pattern, retval + 1); + return -EINVAL; + } - if (!error) - validate_coredump_safety(); + validate_coredump_safety(); return error; } -- 2.47.2