[PATCH v2 02/25] ima: Align ima_post_path_mknod() definition with LSM infrastructure
From: Roberto Sassu <hidden>
Date: 2023-08-31 10:43:25
Also in:
keyrings, linux-fsdevel, linux-integrity, linux-nfs, lkml, selinux
Subsystem:
extended verification module (evm), filesystems (vfs and infrastructure), integrity measurement architecture (ima), security subsystem, the rest · Maintainers:
Mimi Zohar, Roberto Sassu, Alexander Viro, Christian Brauner, Dmitry Kasatkin, Paul Moore, James Morris, "Serge E. Hallyn", Linus Torvalds
From: Roberto Sassu <roberto.sassu@huawei.com> 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(). 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 <roberto.sassu@huawei.com> --- 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; + if (!ima_policy_flag || !S_ISREG(inode->i_mode)) return;
--
2.34.1