diff options
| -rw-r--r-- | fs/internal.h | 5 | ||||
| -rw-r--r-- | fs/namei.c | 66 |
2 files changed, 54 insertions, 17 deletions
diff --git a/fs/internal.h b/fs/internal.h index 8a9f5fa840f1..a6fd56c68b11 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -42,6 +42,11 @@ static inline int __sync_blockdev(struct block_device *bdev, int wait) extern void __init chrdev_init(void); /* + * namei.c + */ +extern int __inode_permission(struct inode *, int); + +/* * namespace.c */ extern int copy_mount_options(const void __user *, unsigned long *); diff --git a/fs/namei.c b/fs/namei.c index c6dcb4c8f86c..1b6474687698 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -315,31 +315,22 @@ static inline int do_inode_permission(struct inode *inode, int mask) } /** - * inode_permission - check for access rights to a given inode - * @inode: inode to check permission on - * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) + * __inode_permission - Check for access rights to a given inode + * @inode: Inode to check permission on + * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) * - * Used to check for read/write/execute permissions on an inode. - * We use "fsuid" for this, letting us set arbitrary permissions - * for filesystem access without changing the "normal" uids which - * are used for other things. + * Check for read/write/execute permissions on an inode. * * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. + * + * This does not check for a read-only file system. You probably want + * inode_permission(). */ -int inode_permission(struct inode *inode, int mask) +int __inode_permission(struct inode *inode, int mask) { int retval; if (unlikely(mask & MAY_WRITE)) { - umode_t mode = inode->i_mode; - - /* - * Nobody gets write access to a read-only fs. - */ - if (IS_RDONLY(inode) && - (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) - return -EROFS; - /* * Nobody gets write access to an immutable file. */ @@ -359,6 +350,47 @@ int inode_permission(struct inode *inode, int mask) } /** + * sb_permission - Check superblock-level permissions + * @sb: Superblock of inode to check permission on + * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) + * + * Separate out file-system wide checks from inode-specific permission checks. + */ +static int sb_permission(struct super_block *sb, struct inode *inode, int mask) +{ + if (unlikely(mask & MAY_WRITE)) { + umode_t mode = inode->i_mode; + + /* Nobody gets write access to a read-only fs. */ + if ((sb->s_flags & MS_RDONLY) && + (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) + return -EROFS; + } + return 0; +} + +/** + * inode_permission - Check for access rights to a given inode + * @inode: Inode to check permission on + * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) + * + * Check for read/write/execute permissions on an inode. We use fs[ug]id for + * this, letting us set arbitrary permissions for filesystem access without + * changing the "normal" UIDs which are used for other things. + * + * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. + */ +int inode_permission(struct inode *inode, int mask) +{ + int retval; + + retval = sb_permission(inode->i_sb, inode, mask); + if (retval) + return retval; + return __inode_permission(inode, mask); +} + +/** * path_get - get a reference to a path * @path: path to get the reference to * |