[PATCH] r/o bind mounts: elevate write count for do_utimes()
Now includes fix for oops seen by akpm.
"never let a libc developer write your kernel code" - hch
"nor, apparently, a kernel developer" - akpm
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/utimes.c b/fs/utimes.c
index b18da9c..a2bef77 100644
--- a/fs/utimes.c
+++ b/fs/utimes.c
@@ -2,6 +2,7 @@
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/linkage.h>
+#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/sched.h>
#include <linux/stat.h>
@@ -59,6 +60,7 @@
struct inode *inode;
struct iattr newattrs;
struct file *f = NULL;
+ struct vfsmount *mnt;
error = -EINVAL;
if (times && (!nsec_valid(times[0].tv_nsec) ||
@@ -79,18 +81,20 @@
if (!f)
goto out;
dentry = f->f_path.dentry;
+ mnt = f->f_path.mnt;
} else {
error = __user_walk_fd(dfd, filename, (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW, &nd);
if (error)
goto out;
dentry = nd.path.dentry;
+ mnt = nd.path.mnt;
}
inode = dentry->d_inode;
- error = -EROFS;
- if (IS_RDONLY(inode))
+ error = mnt_want_write(mnt);
+ if (error)
goto dput_and_out;
/* Don't worry, the checks are done in inode_change_ok() */
@@ -98,7 +102,7 @@
if (times) {
error = -EPERM;
if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
- goto dput_and_out;
+ goto mnt_drop_write_and_out;
if (times[0].tv_nsec == UTIME_OMIT)
newattrs.ia_valid &= ~ATTR_ATIME;
@@ -118,22 +122,24 @@
} else {
error = -EACCES;
if (IS_IMMUTABLE(inode))
- goto dput_and_out;
+ goto mnt_drop_write_and_out;
if (!is_owner_or_cap(inode)) {
if (f) {
if (!(f->f_mode & FMODE_WRITE))
- goto dput_and_out;
+ goto mnt_drop_write_and_out;
} else {
error = vfs_permission(&nd, MAY_WRITE);
if (error)
- goto dput_and_out;
+ goto mnt_drop_write_and_out;
}
}
}
mutex_lock(&inode->i_mutex);
error = notify_change(dentry, &newattrs);
mutex_unlock(&inode->i_mutex);
+mnt_drop_write_and_out:
+ mnt_drop_write(mnt);
dput_and_out:
if (f)
fput(f);