From: "Christian Göttsche" <cgoettsche@seltendoof.de>
Cc: "Christian Göttsche" <cgzones@googlemail.com>,
"Serge Hallyn" <serge@hallyn.com>, "Jan Kara" <jack@suse.com>,
"Julia Lawall" <Julia.Lawall@inria.fr>,
"Nicolas Palix" <nicolas.palix@imag.fr>,
linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org, cocci@inria.fr,
"Theodore Ts'o" <tytso@mit.edu>,
"Andreas Dilger" <adilger.kernel@dilger.ca>,
linux-ext4@vger.kernel.org
Subject: [cocci] [PATCH v2 03/11] ext4: reorder capability check last
Date: Sun, 2 Mar 2025 17:06:39 +0100 [thread overview]
Message-ID: <20250302160657.127253-2-cgoettsche@seltendoof.de> (raw)
In-Reply-To: <20250302160657.127253-1-cgoettsche@seltendoof.de>
From: Christian Göttsche <cgzones@googlemail.com>
capable() calls refer to enabled LSMs whether to permit or deny the
request. This is relevant in connection with SELinux, where a
capability check results in a policy decision and by default a denial
message on insufficient permission is issued.
It can lead to three undesired cases:
1. A denial message is generated, even in case the operation was an
unprivileged one and thus the syscall succeeded, creating noise.
2. To avoid the noise from 1. the policy writer adds a rule to ignore
those denial messages, hiding future syscalls, where the task
performs an actual privileged operation, leading to hidden limited
functionality of that task.
3. To avoid the noise from 1. the policy writer adds a rule to permit
the task the requested capability, while it does not need it,
violating the principle of least privilege.
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Reviewed-by: Serge Hallyn <serge@hallyn.com>
---
fs/ext4/balloc.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index 8042ad873808..c48fd36b2d74 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -649,8 +649,8 @@ static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
/* Hm, nope. Are (enough) root reserved clusters available? */
if (uid_eq(sbi->s_resuid, current_fsuid()) ||
(!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
- capable(CAP_SYS_RESOURCE) ||
- (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
+ (flags & EXT4_MB_USE_ROOT_BLOCKS) ||
+ capable(CAP_SYS_RESOURCE)) {
if (free_clusters >= (nclusters + dirty_clusters +
resv_clusters))
--
2.47.2
next prev parent reply other threads:[~2025-03-04 9:58 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-02 16:06 [cocci] [PATCH v2 02/11] quota: reorder capability check last Christian Göttsche
2025-03-02 16:06 ` Christian Göttsche [this message]
2025-03-04 10:51 ` [cocci] [PATCH v2 03/11] ext4: " Jan Kara
2025-03-02 16:06 ` [cocci] [PATCH v2 04/11] hugetlbfs: " Christian Göttsche
2025-03-02 16:06 ` [cocci] [PATCH v2 05/11] genwqe: " Christian Göttsche
2025-03-02 16:06 ` [cocci] [PATCH v2 06/11] ubifs: " Christian Göttsche
2025-03-03 13:49 ` Zhihao Cheng
2025-03-02 16:06 ` [cocci] [PATCH v2 07/11] drm/panthor: " Christian Göttsche
2025-03-02 16:06 ` [cocci] [PATCH v2 08/11] ipv4: " Christian Göttsche
2025-03-02 18:24 ` Eric Dumazet
2025-03-02 16:06 ` [cocci] [PATCH v2 09/11] fs: " Christian Göttsche
2025-03-02 16:06 ` [cocci] [PATCH v2 10/11] skbuff: " Christian Göttsche
2025-03-04 14:06 ` Willem de Bruijn
2025-03-02 16:06 ` [cocci] [PATCH v2 11/11] infiniband: " Christian Göttsche
2025-03-03 19:04 ` Leon Romanovsky
2025-03-02 16:06 ` [cocci] [PATCH v2 01/11] coccinelle: Add script to reorder capable() calls Christian Göttsche
2025-03-02 16:53 ` Casey Schaufler
2025-03-02 18:35 ` Christian Göttsche
2025-03-18 3:41 ` Theodore Ts'o
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20250302160657.127253-2-cgoettsche@seltendoof.de \
--to=cgoettsche@seltendoof.de \
--cc=Julia.Lawall@inria.fr \
--cc=adilger.kernel@dilger.ca \
--cc=cgzones@googlemail.com \
--cc=cocci@inria.fr \
--cc=jack@suse.com \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=nicolas.palix@imag.fr \
--cc=serge@hallyn.com \
--cc=tytso@mit.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).