On Wed, 2023-10-11 at 10:38 -0400, Mimi Zohar wrote: > On Mon, 2023-09-04 at 15:33 +0200, Roberto Sassu wrote: > > From: Roberto Sassu <[email protected]> > > > > 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 <[email protected]> > > --- > > 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?
You are right, I can remove the first check. Thanks Roberto > > if (!ima_policy_flag || !S_ISREG(inode->i_mode)) > > return; > >
