diff options
| -rw-r--r-- | fs/overlayfs/copy_up.c | 15 | ||||
| -rw-r--r-- | include/linux/lsm_hooks.h | 11 | ||||
| -rw-r--r-- | include/linux/security.h | 6 | ||||
| -rw-r--r-- | security/security.c | 8 |
4 files changed, 40 insertions, 0 deletions
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index 54e5d6681786..c297b1f5a05e 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -246,6 +246,8 @@ static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir, struct dentry *upper = NULL; umode_t mode = stat->mode; int err; + const struct cred *old_creds = NULL; + struct cred *new_creds = NULL; newdentry = ovl_lookup_temp(workdir, dentry); err = PTR_ERR(newdentry); @@ -258,10 +260,23 @@ static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir, if (IS_ERR(upper)) goto out1; + err = security_inode_copy_up(dentry, &new_creds); + if (err < 0) + goto out2; + + if (new_creds) + old_creds = override_creds(new_creds); + /* Can't properly set mode on creation because of the umask */ stat->mode &= S_IFMT; err = ovl_create_real(wdir, newdentry, stat, link, NULL, true); stat->mode = mode; + + if (new_creds) { + revert_creds(old_creds); + put_cred(new_creds); + } + if (err) goto out2; diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index 101bf19c0f41..cb69fc829053 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -401,6 +401,15 @@ * @inode contains a pointer to the inode. * @secid contains a pointer to the location where result will be saved. * In case of failure, @secid will be set to zero. + * @inode_copy_up: + * A file is about to be copied up from lower layer to upper layer of + * overlay filesystem. Security module can prepare a set of new creds + * and modify as need be and return new creds. Caller will switch to + * new creds temporarily to create new file and release newly allocated + * creds. + * @src indicates the union dentry of file that is being copied up. + * @new pointer to pointer to return newly allocated creds. + * Returns 0 on success or a negative error code on error. * * Security hooks for file operations * @@ -1425,6 +1434,7 @@ union security_list_options { int (*inode_listsecurity)(struct inode *inode, char *buffer, size_t buffer_size); void (*inode_getsecid)(struct inode *inode, u32 *secid); + int (*inode_copy_up)(struct dentry *src, struct cred **new); int (*file_permission)(struct file *file, int mask); int (*file_alloc_security)(struct file *file); @@ -1696,6 +1706,7 @@ struct security_hook_heads { struct list_head inode_setsecurity; struct list_head inode_listsecurity; struct list_head inode_getsecid; + struct list_head inode_copy_up; struct list_head file_permission; struct list_head file_alloc_security; struct list_head file_free_security; diff --git a/include/linux/security.h b/include/linux/security.h index 7831cd57bcf7..c5b0ccd6c8b6 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -282,6 +282,7 @@ int security_inode_getsecurity(struct inode *inode, const char *name, void **buf int security_inode_setsecurity(struct inode *inode, const char *name, const void *value, size_t size, int flags); int security_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer_size); void security_inode_getsecid(struct inode *inode, u32 *secid); +int security_inode_copy_up(struct dentry *src, struct cred **new); int security_file_permission(struct file *file, int mask); int security_file_alloc(struct file *file); void security_file_free(struct file *file); @@ -758,6 +759,11 @@ static inline void security_inode_getsecid(struct inode *inode, u32 *secid) *secid = 0; } +static inline int security_inode_copy_up(struct dentry *src, struct cred **new) +{ + return 0; +} + static inline int security_file_permission(struct file *file, int mask) { return 0; diff --git a/security/security.c b/security/security.c index 4838e7fefa1f..f2a7f27bd3e9 100644 --- a/security/security.c +++ b/security/security.c @@ -748,6 +748,12 @@ void security_inode_getsecid(struct inode *inode, u32 *secid) call_void_hook(inode_getsecid, inode, secid); } +int security_inode_copy_up(struct dentry *src, struct cred **new) +{ + return call_int_hook(inode_copy_up, 0, src, new); +} +EXPORT_SYMBOL(security_inode_copy_up); + int security_file_permission(struct file *file, int mask) { int ret; @@ -1684,6 +1690,8 @@ struct security_hook_heads security_hook_heads = { LIST_HEAD_INIT(security_hook_heads.inode_listsecurity), .inode_getsecid = LIST_HEAD_INIT(security_hook_heads.inode_getsecid), + .inode_copy_up = + LIST_HEAD_INIT(security_hook_heads.inode_copy_up), .file_permission = LIST_HEAD_INIT(security_hook_heads.file_permission), .file_alloc_security = |