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Wed, 11 Oct 2023 14:38:08 +0000 (GMT) Message-ID: Subject: Re: [PATCH v3 02/25] ima: Align ima_post_path_mknod() definition with LSM infrastructure From: Mimi Zohar To: Roberto Sassu , viro@zeniv.linux.org.uk, brauner@kernel.org, chuck.lever@oracle.com, jlayton@kernel.org, neilb@suse.de, kolga@netapp.com, Dai.Ngo@oracle.com, tom@talpey.com, dmitry.kasatkin@gmail.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, dhowells@redhat.com, jarkko@kernel.org, stephen.smalley.work@gmail.com, eparis@parisplace.org, casey@schaufler-ca.com Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, keyrings@vger.kernel.org, selinux@vger.kernel.org, Roberto Sassu Date: Wed, 11 Oct 2023 10:38:08 -0400 In-Reply-To: <20230904133415.1799503-3-roberto.sassu@huaweicloud.com> References: <20230904133415.1799503-1-roberto.sassu@huaweicloud.com> <20230904133415.1799503-3-roberto.sassu@huaweicloud.com> Content-Type: text/plain; charset="ISO-8859-15" X-Mailer: Evolution 3.28.5 (3.28.5-22.el8) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: QVsVQlDn-wAz8Uyi9OSmRgCBMpneIJFI X-Proofpoint-ORIG-GUID: 56WOXHa1T-ZiyjPUwv0xHI5wq_xiNMpW X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.267,Aquarius:18.0.980,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-10-11_09,2023-10-11_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 lowpriorityscore=0 suspectscore=0 clxscore=1015 malwarescore=0 priorityscore=1501 mlxscore=0 phishscore=0 mlxlogscore=982 adultscore=0 spamscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2309180000 definitions=main-2310110129 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On Mon, 2023-09-04 at 15:33 +0200, Roberto Sassu wrote: > From: Roberto Sassu > > Change ima_post_path_mknod() definition, so that it can be registered as > implementation of the path_post_mknod hook. Since LSMs see a umask-stripped > mode from security_path_mknod(), pass the same to ima_post_path_mknod() as > well. > Also, make sure that ima_post_path_mknod() is executed only if > (mode & S_IFMT) is equal to zero or S_IFREG. > > Add this check to take into account the different placement of the > path_post_mknod hook (to be introduced) in do_mknodat(). Move "(to be introduced)" to when it is first mentioned. > Since the new hook > will be placed after the switch(), the check ensures that > ima_post_path_mknod() is invoked as originally intended when it is > registered as implementation of path_post_mknod. > > Signed-off-by: Roberto Sassu > --- > fs/namei.c | 9 ++++++--- > include/linux/ima.h | 7 +++++-- > security/integrity/ima/ima_main.c | 10 +++++++++- > 3 files changed, 20 insertions(+), 6 deletions(-) > > diff --git a/fs/namei.c b/fs/namei.c > index e56ff39a79bc..c5e96f716f98 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -4024,6 +4024,7 @@ static int do_mknodat(int dfd, struct filename *name, umode_t mode, > struct path path; > int error; > unsigned int lookup_flags = 0; > + umode_t mode_stripped; > > error = may_mknod(mode); > if (error) > @@ -4034,8 +4035,9 @@ static int do_mknodat(int dfd, struct filename *name, umode_t mode, > if (IS_ERR(dentry)) > goto out1; > > - error = security_path_mknod(&path, dentry, > - mode_strip_umask(path.dentry->d_inode, mode), dev); > + mode_stripped = mode_strip_umask(path.dentry->d_inode, mode); > + > + error = security_path_mknod(&path, dentry, mode_stripped, dev); > if (error) > goto out2; > > @@ -4045,7 +4047,8 @@ static int do_mknodat(int dfd, struct filename *name, umode_t mode, > error = vfs_create(idmap, path.dentry->d_inode, > dentry, mode, true); > if (!error) > - ima_post_path_mknod(idmap, dentry); > + ima_post_path_mknod(idmap, &path, dentry, > + mode_stripped, dev); > break; > case S_IFCHR: case S_IFBLK: > error = vfs_mknod(idmap, path.dentry->d_inode, > diff --git a/include/linux/ima.h b/include/linux/ima.h > index 910a2f11a906..179ce52013b2 100644 > --- a/include/linux/ima.h > +++ b/include/linux/ima.h > @@ -32,7 +32,8 @@ extern int ima_read_file(struct file *file, enum kernel_read_file_id id, > extern int ima_post_read_file(struct file *file, void *buf, loff_t size, > enum kernel_read_file_id id); > extern void ima_post_path_mknod(struct mnt_idmap *idmap, > - struct dentry *dentry); > + const struct path *dir, struct dentry *dentry, > + umode_t mode, unsigned int dev); > extern int ima_file_hash(struct file *file, char *buf, size_t buf_size); > extern int ima_inode_hash(struct inode *inode, char *buf, size_t buf_size); > extern void ima_kexec_cmdline(int kernel_fd, const void *buf, int size); > @@ -114,7 +115,9 @@ static inline int ima_post_read_file(struct file *file, void *buf, loff_t size, > } > > static inline void ima_post_path_mknod(struct mnt_idmap *idmap, > - struct dentry *dentry) > + const struct path *dir, > + struct dentry *dentry, > + umode_t mode, unsigned int dev) > { > return; > } > diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c > index 365db0e43d7c..76eba92d7f10 100644 > --- a/security/integrity/ima/ima_main.c > +++ b/security/integrity/ima/ima_main.c > @@ -696,18 +696,26 @@ void ima_post_create_tmpfile(struct mnt_idmap *idmap, > /** > * ima_post_path_mknod - mark as a new inode > * @idmap: idmap of the mount the inode was found from > + * @dir: path structure of parent of the new file > * @dentry: newly created dentry > + * @mode: mode of the new file > + * @dev: undecoded device number > * > * Mark files created via the mknodat syscall as new, so that the > * file data can be written later. > */ > void ima_post_path_mknod(struct mnt_idmap *idmap, > - struct dentry *dentry) > + const struct path *dir, struct dentry *dentry, > + umode_t mode, unsigned int dev) > { > struct integrity_iint_cache *iint; > struct inode *inode = dentry->d_inode; > int must_appraise; > > + /* See do_mknodat(), IMA is executed for case 0: and case S_IFREG: */ > + if ((mode & S_IFMT) != 0 && (mode & S_IFMT) != S_IFREG) > + return; > + There's already a check below to make sure that this is a regular file. Are both needed? > if (!ima_policy_flag || !S_ISREG(inode->i_mode)) > return; >