Allow move_mount() to work with NULL path arguments.
Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
---
fs/namespace.c | 93 +++++++++++++++++++++++++++++++++++-------------------
include/linux/fs.h | 1 +
2 files changed, 61 insertions(+), 33 deletions(-)
diff --git a/fs/namespace.c b/fs/namespace.c
index 66b9cea1cf66..612f73481d35 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2465,6 +2465,7 @@ int count_mounts(struct mnt_namespace *ns, struct mount *mnt)
enum mnt_tree_flags_t {
MNT_TREE_MOVE = BIT(0),
MNT_TREE_BENEATH = BIT(1),
+ MNT_TREE_PROPAGATION = BIT(2),
};
/**
@@ -3434,8 +3435,8 @@ static int can_move_mount_beneath(const struct path *from,
return 0;
}
-static int do_move_mount(struct path *old_path, struct path *new_path,
- bool beneath)
+static int do_move_mount(struct path *old_path,
+ struct path *new_path, enum mnt_tree_flags_t flags)
{
struct mnt_namespace *ns;
struct mount *p;
@@ -3443,8 +3444,7 @@ static int do_move_mount(struct path *old_path, struct path *new_path,
struct mount *parent;
struct mountpoint *mp, *old_mp;
int err;
- bool attached;
- enum mnt_tree_flags_t flags = 0;
+ bool attached, beneath = flags & MNT_TREE_BENEATH;
mp = do_lock_mount(new_path, beneath);
if (IS_ERR(mp))
@@ -3545,7 +3545,7 @@ static int do_move_mount_old(struct path *path, const char *old_name)
if (err)
return err;
- err = do_move_mount(&old_path, path, false);
+ err = do_move_mount(&old_path, path, 0);
path_put(&old_path);
return err;
}
@@ -4386,6 +4386,21 @@ SYSCALL_DEFINE3(fsmount, int, fs_fd, unsigned int, flags,
return ret;
}
+static inline int vfs_move_mount(struct path *from_path, struct path *to_path,
+ enum mnt_tree_flags_t mflags)
+{
+ int ret;
+
+ ret = security_move_mount(from_path, to_path);
+ if (ret)
+ return ret;
+
+ if (mflags & MNT_TREE_PROPAGATION)
+ return do_set_group(from_path, to_path);
+
+ return do_move_mount(from_path, to_path, mflags);
+}
+
/*
* Move a mount from one place to another. In combination with
* fsopen()/fsmount() this is used to install a new mount and in combination
@@ -4399,8 +4414,12 @@ SYSCALL_DEFINE5(move_mount,
int, to_dfd, const char __user *, to_pathname,
unsigned int, flags)
{
- struct path from_path, to_path;
- unsigned int lflags;
+ struct path to_path __free(path_put) = {};
+ struct path from_path __free(path_put) = {};
+ struct filename *to_name __free(putname) = NULL;
+ struct filename *from_name __free(putname) = NULL;
+ unsigned int lflags, uflags;
+ enum mnt_tree_flags_t mflags = 0;
int ret = 0;
if (!may_mount())
@@ -4413,43 +4432,51 @@ SYSCALL_DEFINE5(move_mount,
(MOVE_MOUNT_BENEATH | MOVE_MOUNT_SET_GROUP))
return -EINVAL;
- /* If someone gives a pathname, they aren't permitted to move
- * from an fd that requires unmount as we can't get at the flag
- * to clear it afterwards.
- */
+ if (flags & MOVE_MOUNT_SET_GROUP) mflags |= MNT_TREE_PROPAGATION;
+ if (flags & MOVE_MOUNT_BENEATH) mflags |= MNT_TREE_BENEATH;
+
lflags = 0;
if (flags & MOVE_MOUNT_F_SYMLINKS) lflags |= LOOKUP_FOLLOW;
if (flags & MOVE_MOUNT_F_AUTOMOUNTS) lflags |= LOOKUP_AUTOMOUNT;
- if (flags & MOVE_MOUNT_F_EMPTY_PATH) lflags |= LOOKUP_EMPTY;
-
- ret = user_path_at(from_dfd, from_pathname, lflags, &from_path);
- if (ret < 0)
- return ret;
+ if (flags & MOVE_MOUNT_F_EMPTY_PATH) uflags = AT_EMPTY_PATH;
+ from_name = getname_maybe_null(from_pathname, uflags);
+ if (IS_ERR(from_name))
+ return PTR_ERR(from_name);
lflags = 0;
if (flags & MOVE_MOUNT_T_SYMLINKS) lflags |= LOOKUP_FOLLOW;
if (flags & MOVE_MOUNT_T_AUTOMOUNTS) lflags |= LOOKUP_AUTOMOUNT;
- if (flags & MOVE_MOUNT_T_EMPTY_PATH) lflags |= LOOKUP_EMPTY;
+ if (flags & MOVE_MOUNT_T_EMPTY_PATH) uflags = AT_EMPTY_PATH;
+ to_name = getname_maybe_null(to_pathname, uflags);
+ if (IS_ERR(to_name))
+ return PTR_ERR(to_name);
+
+ if (!to_name && to_dfd >= 0) {
+ CLASS(fd_raw, f_to)(to_dfd);
+ if (fd_empty(f_to))
+ return -EBADF;
+
+ to_path = fd_file(f_to)->f_path;
+ path_get(&to_path);
+ } else {
+ ret = filename_lookup(to_dfd, to_name, lflags, &to_path, NULL);
+ if (ret)
+ return ret;
+ }
- ret = user_path_at(to_dfd, to_pathname, lflags, &to_path);
- if (ret < 0)
- goto out_from;
+ if (!from_name && from_dfd >= 0) {
+ CLASS(fd_raw, f_from)(from_dfd);
+ if (fd_empty(f_from))
+ return -EBADF;
- ret = security_move_mount(&from_path, &to_path);
- if (ret < 0)
- goto out_to;
+ return vfs_move_mount(&fd_file(f_from)->f_path, &to_path, mflags);
+ }
- if (flags & MOVE_MOUNT_SET_GROUP)
- ret = do_set_group(&from_path, &to_path);
- else
- ret = do_move_mount(&from_path, &to_path,
- (flags & MOVE_MOUNT_BENEATH));
+ ret = filename_lookup(from_dfd, from_name, lflags, &from_path, NULL);
+ if (ret)
+ return ret;
-out_to:
- path_put(&to_path);
-out_from:
- path_put(&from_path);
- return ret;
+ return vfs_move_mount(&from_path, &to_path, mflags);
}
/*
diff --git a/include/linux/fs.h b/include/linux/fs.h
index e71d58c7f59c..7e9df867538d 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2855,6 +2855,7 @@ static inline struct filename *getname_maybe_null(const char __user *name, int f
return __getname_maybe_null(name);
}
extern void putname(struct filename *name);
+DEFINE_FREE(putname, struct filename *, if (!IS_ERR_OR_NULL(_T)) putname(_T))
extern int finish_open(struct file *file, struct dentry *dentry,
int (*open)(struct inode *, struct file *));
--
2.47.2
