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 DA29A236431; Fri, 16 May 2025 11:26:22 +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=1747394783; cv=none; b=K5jQ0vg7F2qbXjWJOmAuCz3gIxYCYXN/pqQB1KTkDAa0oJ4kOF5UL1Ubno1k47h5PrmB9hUucw9dbsp6isjk9wCrYM3FckWRImsbWYy/xFzfMa4GgOH4AX++1HuT45gnVHlJ7l7oaSv+HO4KncRTBQ/LQdc0cTLyg/iL55tuu3s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747394783; c=relaxed/simple; bh=cdHC8XIcBNIdLFjlHlwiRrtkhnKb7FpbkKLOq0IziuI=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=LSgJhsHmelYMTgViN2o20iAujlUgrgoRhBUS+d305esUpcAXEv+RJOm3uXEa1QU6vOAIoWBd96qp/J9ZqBfcwqKrfRHHld+lo7l7+5acYGD1AqIOpL4Epa/TZ5yP+G+5jqUT5eJyVsdMSuQOxb6DmDuR7+hHiQHV9rRFzcNLCSg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=kyQJhYJI; 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="kyQJhYJI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3EB1AC4CEE4; Fri, 16 May 2025 11:26:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747394782; bh=cdHC8XIcBNIdLFjlHlwiRrtkhnKb7FpbkKLOq0IziuI=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=kyQJhYJI9pGnMPXVFWedYdnvczVPVcbPy74MhDh7FnQeSybufq49b8RL4d2dGKH+n HxdvUlyi4fHZZRoUOB1Vgq451o2pttbclrDkLZgb9P0W5drdepSPnJ9DRBzPiW+1PH XNHRJNuqm9aVHuyq1p/cE/5BbM5xHD0uYeXt97GjvAx0sQS7VmrB0+k0BuOAMXDjxj LXH2+NoK2BfrKwbpv+VhcWBaK4nUPLftgu7Md7/sKpMcG/VdVy+Z2hxiyqtNTurD1b UW0gA6b4tjMIIfwbzkWwYIez3lYFnswtIkS78EKuKlE9W0qWS3+5WDxkG6XOJiHlFM Tah9xrmBty54Q== From: Christian Brauner Date: Fri, 16 May 2025 13:25:34 +0200 Subject: [PATCH v8 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: <20250516-work-coredump-socket-v8-7-664f3caf2516@kernel.org> References: <20250516-work-coredump-socket-v8-0-664f3caf2516@kernel.org> In-Reply-To: <20250516-work-coredump-socket-v8-0-664f3caf2516@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-6f78e X-Developer-Signature: v=1; a=openpgp-sha256; l=1893; i=brauner@kernel.org; h=from:subject:message-id; bh=cdHC8XIcBNIdLFjlHlwiRrtkhnKb7FpbkKLOq0IziuI=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWSoK2zdde9lejNPSz732qlnNYUq0+MXLnj25NSkP7umO zUd+GR/r6OUhUGMi0FWTJHFod0kXG45T8Vmo0wNmDmsTCBDGLg4BWAi5QqMDJ0bH3EfnXi663Px +292Lpp7Vhw0PSpT1j6//U5JWMrlvxoM/51Sn9/oz/Hvv1JW8HypjWjwibrLHMueW55IuM1SGf2 2kx0A 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. Acked-by: Luca Boccassi Reviewed-by: Jann Horn Reviewed-by: Alexander Mikhalitsyn Signed-off-by: Christian Brauner --- fs/coredump.c | 37 ++++++++++++++++++++++++++++++++++--- 1 file changed, 34 insertions(+), 3 deletions(-) diff --git a/fs/coredump.c b/fs/coredump.c index 7b9a659683fc..c5c57e8e496f 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -1215,13 +1215,44 @@ void validate_coredump_safety(void) } } +static inline bool check_coredump_socket(void) +{ + if (core_pattern[0] != '@') + return true; + + /* + * Coredump socket must be located in the initial mount + * namespace. Don't give the impression that anything else is + * supported right now. + */ + if (current->nsproxy->mnt_ns != init_task.nsproxy->mnt_ns) + return false; + + /* Must be an absolute path. */ + if (*(core_pattern + 1) != '/') + 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()) { + strscpy(core_pattern, old_core_pattern, retval + 1); + return -EINVAL; + } - if (!error) - validate_coredump_safety(); + validate_coredump_safety(); return error; } -- 2.47.2