check ATTR_SIZE contraints in inode_change_ok
Make sure we check the truncate constraints early on in ->setattr by adding
those checks to inode_change_ok. Also clean up and document inode_change_ok
to make this obvious.
As a fallout we don't have to call inode_newsize_ok from simple_setsize and
simplify it down to a truncate_setsize which doesn't return an error. This
simplifies a lot of setattr implementations and means we use truncate_setsize
almost everywhere. Get rid of fat_setsize now that it's trivial and mark
ext2_setsize static to make the calling convention obvious.
Keep the inode_newsize_ok in vmtruncate for now as all callers need an
audit for its removal anyway.
Note: setattr code in ecryptfs doesn't call inode_change_ok at all and
needs a deeper audit, but that is left for later.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/attr.c b/fs/attr.c
index ed44d8a..7ca4181 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -14,35 +14,53 @@
#include <linux/fcntl.h>
#include <linux/security.h>
-/* Taken over from the old code... */
-
-/* POSIX UID/GID verification for setting inode attributes. */
+/**
+ * inode_change_ok - check if attribute changes to an inode are allowed
+ * @inode: inode to check
+ * @attr: attributes to change
+ *
+ * Check if we are allowed to change the attributes contained in @attr
+ * in the given inode. This includes the normal unix access permission
+ * checks, as well as checks for rlimits and others.
+ *
+ * Should be called as the first thing in ->setattr implementations,
+ * possibly after taking additional locks.
+ */
int inode_change_ok(const struct inode *inode, struct iattr *attr)
{
- int retval = -EPERM;
unsigned int ia_valid = attr->ia_valid;
+ /*
+ * First check size constraints. These can't be overriden using
+ * ATTR_FORCE.
+ */
+ if (ia_valid & ATTR_SIZE) {
+ int error = inode_newsize_ok(inode, attr->ia_size);
+ if (error)
+ return error;
+ }
+
/* If force is set do it anyway. */
if (ia_valid & ATTR_FORCE)
- goto fine;
+ return 0;
/* Make sure a caller can chown. */
if ((ia_valid & ATTR_UID) &&
(current_fsuid() != inode->i_uid ||
attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN))
- goto error;
+ return -EPERM;
/* Make sure caller can chgrp. */
if ((ia_valid & ATTR_GID) &&
(current_fsuid() != inode->i_uid ||
(!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid)) &&
!capable(CAP_CHOWN))
- goto error;
+ return -EPERM;
/* Make sure a caller can chmod. */
if (ia_valid & ATTR_MODE) {
if (!is_owner_or_cap(inode))
- goto error;
+ return -EPERM;
/* Also check the setgid bit! */
if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
inode->i_gid) && !capable(CAP_FSETID))
@@ -52,12 +70,10 @@
/* Check for setting the inode time. */
if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) {
if (!is_owner_or_cap(inode))
- goto error;
+ return -EPERM;
}
-fine:
- retval = 0;
-error:
- return retval;
+
+ return 0;
}
EXPORT_SYMBOL(inode_change_ok);
@@ -113,7 +129,7 @@
*
* setattr_copy updates the inode's metadata with that specified
* in attr. Noticably missing is inode size update, which is more complex
- * as it requires pagecache updates. See simple_setsize.
+ * as it requires pagecache updates.
*
* The inode is not marked as dirty after this operation. The rationale is
* that for "simple" filesystems, the struct inode is the inode storage.