From nobody Fri Dec 19 20:34:37 2025 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 5D7D6221296; Wed, 14 May 2025 22:04:34 +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=1747260274; cv=none; b=sbpta92qKF7gy4iVab+HwUGrruVdEc+oYhX25BiiOssbavs66YFGqhkUsc9QvgZ2jqN+jgMds/YHeXCnLUPAXvL4RqPAXF3bhwROy8jNV1lEPXVaHMooQn6GKasgEHj972RhD/uUsJVMB+zEiAwabFDTEoTi+s7py9Uw3weZ5pA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747260274; c=relaxed/simple; bh=GofPJKcSMTqtWvKIscS1eZ3G1JH+s1zbLWmsYPBuvtI=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=MTo1F81qPNF5ldPshU3Ur8jOpi9OOVAWWiCr/7xc4WcLyXbHK1iWuyjHvF+hp2uyXu19QABix+i5VsgH6Yb1m41so93apGq3UE7Ka/pXDkXbvJxKDHLMNpYGaSxohwS3hq/SB664UgFxuvikvLpcVhCntLnfj1TvyURK29+aNjU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=b4VW0Ubv; 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="b4VW0Ubv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8F0C0C4CEEF; Wed, 14 May 2025 22:04:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747260274; bh=GofPJKcSMTqtWvKIscS1eZ3G1JH+s1zbLWmsYPBuvtI=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=b4VW0UbvM1foRVLyhSsYkbutkTtNDGp86d3vZb+EscZ4wdISAFS98lQCq3NzaXiay ZhP0tDP5ZmZ2TC/v97vaS1rvTe++YT0MyFwONocFzQClXNc+fP0gIxz6IpKOjMAdfv Q8K2F5B0m0Wzjt4JFqc+BxmDyzJpkGoDoH+TtN8Cv7tbXaPPn9bE6rxA0L1tSlbEg1 jhCCuNLdGg+fX6Qq9OGJyk+95DUiV3EjaKqxqJdZ+5RhVCPAkx+uwSyjGxDrRu5bD7 itPolyZ6dd+7cXX2Dpb0amdwS9g6WqbrcfcKO4pZLDRvXKYi/J2rZk++3gaUrLiC1b tQK9tYAoQ+dGA== From: Christian Brauner Date: Thu, 15 May 2025 00:03:40 +0200 Subject: [PATCH v7 7/9] coredump: validate socket name as it is written Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250515-work-coredump-socket-v7-7-0a1329496c31@kernel.org> References: <20250515-work-coredump-socket-v7-0-0a1329496c31@kernel.org> In-Reply-To: <20250515-work-coredump-socket-v7-0-0a1329496c31@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=1725; i=brauner@kernel.org; h=from:subject:message-id; bh=GofPJKcSMTqtWvKIscS1eZ3G1JH+s1zbLWmsYPBuvtI=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWSoCntci0xSrJ0wQfNh4ZtD9w89yM3Y/Vzq4yu1Zd+Fn ScaLDsa1lHKwiDGxSArpsji0G4SLrecp2KzUaYGzBxWJpAhDFycAjCRC/0M/z0rNt7Jif9xcMfP WRxXnty4Jm2QLnnrxqdXf7et8pe6cXAhw//84jeTOLYqfTnxO3jRbI5pc+aUr2E2WGrwtW+mg1r 8FlduAA== 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 Reviewed-by: Alexander Mikhalitsyn Reviewed-by: Jann Horn --- fs/coredump.c | 37 ++++++++++++++++++++++++++++++++++--- 1 file changed, 34 insertions(+), 3 deletions(-) diff --git a/fs/coredump.c b/fs/coredump.c index 6ee38e3da108..d4ff08ef03e5 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -1228,13 +1228,44 @@ void validate_coredump_safety(void) } } =20 +static inline bool check_coredump_socket(void) +{ + if (core_pattern[0] !=3D '@') + return true; + + /* + * Coredump socket must be located in the initial mount + * namespace. Don't give the that impression anything else is + * supported right now. + */ + if (current->nsproxy->mnt_ns !=3D init_task.nsproxy->mnt_ns) + return false; + + /* Must be an absolute path. */ + if (*(core_pattern + 1) !=3D '/') + 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 =3D proc_dostring(table, write, buffer, lenp, ppos); + int error; + ssize_t retval; + char old_core_pattern[CORENAME_MAX_SIZE]; + + retval =3D strscpy(old_core_pattern, core_pattern, CORENAME_MAX_SIZE); + + error =3D 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; + } =20 - if (!error) - validate_coredump_safety(); + validate_coredump_safety(); return error; } =20 --=20 2.47.2