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path_connected(): pass mount and dentry separately 

eventually we'll want to do that check *before* mangling
nd->path.dentry...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2020-02-24 15:53:19 -05:00
parent c981a48281
commit 6b03f7edf4
1 changed files with 5 additions and 7 deletions
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12
fs/namei.c
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@ -550,22 +550,20 @@ static int __nd_alloc_stack(struct nameidata *nd)
}
/**
* path_connected - Verify that a path->dentry is below path->mnt.mnt_root
* @path: nameidate to verify
* path_connected - Verify that a dentry is below mnt.mnt_root
*
* Rename can sometimes move a file or directory outside of a bind
* mount, path_connected allows those cases to be detected.
*/
static bool path_connected(const struct path *path)
static bool path_connected(struct vfsmount *mnt, struct dentry *dentry)
{
struct vfsmount *mnt = path->mnt;
struct super_block *sb = mnt->mnt_sb;
/* Bind mounts and multi-root filesystems can have disconnected paths */
if (!(sb->s_iflags & SB_I_MULTIROOT) && (mnt->mnt_root == sb->s_root))
return true;
return is_subdir(path->dentry, mnt->mnt_root);
return is_subdir(dentry, mnt->mnt_root);
}
static inline int nd_alloc_stack(struct nameidata *nd)
@ -1386,7 +1384,7 @@ static int follow_dotdot_rcu(struct nameidata *nd)
return -ECHILD;
nd->path.dentry = parent;
nd->seq = seq;
if (unlikely(!path_connected(&nd->path)))
if (unlikely(!path_connected(nd->path.mnt, parent)))
return -ECHILD;
break;
} else {
@ -1448,7 +1446,7 @@ static int path_parent_directory(struct path *path)
/* rare case of legitimate dget_parent()... */
path->dentry = dget_parent(path->dentry);
dput(old);
if (unlikely(!path_connected(path)))
if (unlikely(!path_connected(path->mnt, path->dentry)))
return -ENOENT;
return 0;
}