aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
-rw-r--r--fs/internal.h5
-rw-r--r--fs/namei.c66
2 files changed, 54 insertions, 17 deletions
diff --git a/fs/internal.h b/fs/internal.h
index 8a9f5fa840f..a6fd56c68b1 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 c6dcb4c8f86..1b647468769 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
*