namei: prepare for idmapped mounts
The various vfs_*() helpers are called by filesystems or by the vfs
itself to perform core operations such as create, link, mkdir, mknod, rename,
rmdir, tmpfile and unlink. Enable them to handle idmapped mounts. If the
inode is accessed through an idmapped mount map it into the
mount's user namespace and pass it down. Afterwards the checks and
operations are identical to non-idmapped mounts. If the initial user
namespace is passed nothing changes so non-idmapped mounts will see
identical behavior as before.
Link: https://lore.kernel.org/r/20210121131959.646623-15-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
index 2e0c3cd..653c8c6 100644
--- a/drivers/base/devtmpfs.c
+++ b/drivers/base/devtmpfs.c
@@ -162,7 +162,7 @@ static int dev_mkdir(const char *name, umode_t mode)
if (IS_ERR(dentry))
return PTR_ERR(dentry);
- err = vfs_mkdir(d_inode(path.dentry), dentry, mode);
+ err = vfs_mkdir(&init_user_ns, d_inode(path.dentry), dentry, mode);
if (!err)
/* mark as kernel-created inode */
d_inode(dentry)->i_private = &thread;
@@ -212,7 +212,8 @@ static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
if (IS_ERR(dentry))
return PTR_ERR(dentry);
- err = vfs_mknod(d_inode(path.dentry), dentry, mode, dev->devt);
+ err = vfs_mknod(&init_user_ns, d_inode(path.dentry), dentry, mode,
+ dev->devt);
if (!err) {
struct iattr newattrs;
@@ -242,7 +243,8 @@ static int dev_rmdir(const char *name)
return PTR_ERR(dentry);
if (d_really_is_positive(dentry)) {
if (d_inode(dentry)->i_private == &thread)
- err = vfs_rmdir(d_inode(parent.dentry), dentry);
+ err = vfs_rmdir(&init_user_ns, d_inode(parent.dentry),
+ dentry);
else
err = -EPERM;
} else {
@@ -330,7 +332,8 @@ static int handle_remove(const char *nodename, struct device *dev)
inode_lock(d_inode(dentry));
notify_change(&init_user_ns, dentry, &newattrs, NULL);
inode_unlock(d_inode(dentry));
- err = vfs_unlink(d_inode(parent.dentry), dentry, NULL);
+ err = vfs_unlink(&init_user_ns, d_inode(parent.dentry),
+ dentry, NULL);
if (!err || err == -ENOENT)
deleted = 1;
}