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(c-76-103-38-92.hsd1.ca.comcast.net. [76.103.38.92]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-301190b98b7sm2353887a91.32.2025.03.12.14.22.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 Mar 2025 14:22:43 -0700 (PDT) From: Ryan Lee To: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, apparmor@lists.ubuntu.com, linux-security-module@vger.kernel.org, selinux@vger.kernel.org Cc: Ryan Lee , Alexander Viro , Christian Brauner , Jan Kara , John Johansen , Paul Moore , James Morris , "Serge E. Hallyn" , =?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?= , =?UTF-8?q?G=C3=BCnther=20Noack?= , Stephen Smalley , Ondrej Mosnacek , Casey Schaufler , Kentaro Takeda , Tetsuo Handa Subject: [RFC PATCH 1/6] fs: invoke LSM file_open hook in do_dentry_open for O_PATH fds as well Date: Wed, 12 Mar 2025 14:21:41 -0700 Message-ID: <20250312212148.274205-2-ryan.lee@canonical.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250312212148.274205-1-ryan.lee@canonical.com> References: <20250312212148.274205-1-ryan.lee@canonical.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Currently, opening O_PATH file descriptors completely bypasses the LSM infrastructure. Invoking the LSM file_open hook for O_PATH fds will be necessary for e.g. mediating the fsmount() syscall. Signed-off-by: Ryan Lee --- fs/open.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/fs/open.c b/fs/open.c index 30bfcddd505d..0f8542bf6cd4 100644 --- a/fs/open.c +++ b/fs/open.c @@ -921,8 +921,13 @@ static int do_dentry_open(struct file *f, if (unlikely(f->f_flags & O_PATH)) { f->f_mode =3D FMODE_PATH | FMODE_OPENED; file_set_fsnotify_mode(f, FMODE_NONOTIFY); f->f_op =3D &empty_fops; - return 0; + /* + * do_o_path in fs/namei.c unconditionally invokes path_put + * after this function returns, so don't path_put the path + * upon LSM rejection of O_PATH opening + */ + return security_file_open(f); } =20 if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) =3D=3D FMODE_READ) { --=20 2.43.0 base-kernel: v6.14-rc6