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[109.81.17.58]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43796abc9b2sm25631899f8f.21.2026.02.16.07.06.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 Feb 2026 07:06:30 -0800 (PST) From: Ondrej Mosnacek To: Jan Kara Cc: Amir Goldstein , Matthew Bobrowski , linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/2] fanotify: call fanotify_events_supported() before path_permission() and security_path_notify() Date: Mon, 16 Feb 2026 16:06:25 +0100 Message-ID: <20260216150625.793013-3-omosnace@redhat.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260216150625.793013-1-omosnace@redhat.com> References: <20260216150625.793013-1-omosnace@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The latter trigger LSM (e.g. SELinux) checks, which will log a denial when permission is denied, so it's better to do them after validity checks to avoid logging a denial when the operation would fail anyway. Fixes: 0b3b094ac9a7 ("fanotify: Disallow permission events for proc filesystem") Signed-off-by: Ondrej Mosnacek --- fs/notify/fanotify/fanotify_user.c | 25 ++++++++++--------------- 1 file changed, 10 insertions(+), 15 deletions(-) diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index 9c9fca2976d2b..bfc4d09e6964a 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -1210,6 +1210,7 @@ static int fanotify_find_path(int dfd, const char __user *filename, *path = fd_file(f)->f_path; path_get(path); + ret = 0; } else { unsigned int lookup_flags = 0; @@ -1219,22 +1220,7 @@ static int fanotify_find_path(int dfd, const char __user *filename, lookup_flags |= LOOKUP_DIRECTORY; ret = user_path_at(dfd, filename, lookup_flags, path); - if (ret) - goto out; } - - /* you can only watch an inode if you have read permissions on it */ - ret = path_permission(path, MAY_READ); - if (ret) { - path_put(path); - goto out; - } - - ret = security_path_notify(path, mask, obj_type); - if (ret) - path_put(path); - -out: return ret; } @@ -2058,6 +2044,15 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask, goto path_put_and_out; } + /* you can only watch an inode if you have read permissions on it */ + ret = path_permission(&path, MAY_READ); + if (ret) + goto path_put_and_out; + + ret = security_path_notify(&path, mask, obj_type); + if (ret) + goto path_put_and_out; + if (fid_mode) { ret = fanotify_test_fsid(path.dentry, flags, &__fsid); if (ret) -- 2.53.0