static HLIST_HEAD(unmounted); /* protected by namespace_sem */
static LIST_HEAD(ex_mountpoints); /* protected by namespace_sem */
-struct mnt_idmap {
- struct user_namespace *owner;
- refcount_t count;
-};
-
-/*
- * Carries the initial idmapping of 0:0:4294967295 which is an identity
- * mapping. This means that {g,u}id 0 is mapped to {g,u}id 0, {g,u}id 1 is
- * mapped to {g,u}id 1, [...], {g,u}id 1000 to {g,u}id 1000, [...].
- */
-struct mnt_idmap nop_mnt_idmap = {
- .owner = &init_user_ns,
- .count = REFCOUNT_INIT(1),
-};
-EXPORT_SYMBOL_GPL(nop_mnt_idmap);
-
struct mount_kattr {
unsigned int attr_set;
unsigned int attr_clr;
#endif
}
-/**
- * mnt_idmap_owner - retrieve owner of the mount's idmapping
- * @idmap: mount idmapping
- *
- * This helper will go away once the conversion to use struct mnt_idmap
- * everywhere has finished at which point the helper will be unexported.
- *
- * Only code that needs to perform permission checks based on the owner of the
- * idmapping will get access to it. All other code will solely rely on
- * idmappings. This will get us type safety so it's impossible to conflate
- * filesystems idmappings with mount idmappings.
- *
- * Return: The owner of the idmapping.
- */
-struct user_namespace *mnt_idmap_owner(const struct mnt_idmap *idmap)
-{
- return idmap->owner;
-}
-EXPORT_SYMBOL_GPL(mnt_idmap_owner);
-
-/**
- * mnt_user_ns - retrieve owner of an idmapped mount
- * @mnt: the relevant vfsmount
- *
- * This helper will go away once the conversion to use struct mnt_idmap
- * everywhere has finished at which point the helper will be unexported.
- *
- * Only code that needs to perform permission checks based on the owner of the
- * idmapping will get access to it. All other code will solely rely on
- * idmappings. This will get us type safety so it's impossible to conflate
- * filesystems idmappings with mount idmappings.
- *
- * Return: The owner of the idmapped.
- */
-struct user_namespace *mnt_user_ns(const struct vfsmount *mnt)
-{
- struct mnt_idmap *idmap = mnt_idmap(mnt);
-
- /* Return the actual owner of the filesystem instead of the nop. */
- if (idmap == &nop_mnt_idmap &&
- !initial_idmapping(mnt->mnt_sb->s_user_ns))
- return mnt->mnt_sb->s_user_ns;
- return mnt_idmap_owner(idmap);
-}
-EXPORT_SYMBOL_GPL(mnt_user_ns);
-
-/**
- * alloc_mnt_idmap - allocate a new idmapping for the mount
- * @mnt_userns: owning userns of the idmapping
- *
- * Allocate a new struct mnt_idmap which carries the idmapping of the mount.
- *
- * Return: On success a new idmap, on error an error pointer is returned.
- */
-static struct mnt_idmap *alloc_mnt_idmap(struct user_namespace *mnt_userns)
-{
- struct mnt_idmap *idmap;
-
- idmap = kzalloc(sizeof(struct mnt_idmap), GFP_KERNEL_ACCOUNT);
- if (!idmap)
- return ERR_PTR(-ENOMEM);
-
- idmap->owner = get_user_ns(mnt_userns);
- refcount_set(&idmap->count, 1);
- return idmap;
-}
-
-/**
- * mnt_idmap_get - get a reference to an idmapping
- * @idmap: the idmap to bump the reference on
- *
- * If @idmap is not the @nop_mnt_idmap bump the reference count.
- *
- * Return: @idmap with reference count bumped if @not_mnt_idmap isn't passed.
- */
-static inline struct mnt_idmap *mnt_idmap_get(struct mnt_idmap *idmap)
-{
- if (idmap != &nop_mnt_idmap)
- refcount_inc(&idmap->count);
-
- return idmap;
-}
-
-/**
- * mnt_idmap_put - put a reference to an idmapping
- * @idmap: the idmap to put the reference on
- *
- * If this is a non-initial idmapping, put the reference count when a mount is
- * released and free it if we're the last user.
- */
-static inline void mnt_idmap_put(struct mnt_idmap *idmap)
-{
- if (idmap != &nop_mnt_idmap && refcount_dec_and_test(&idmap->count)) {
- put_user_ns(idmap->owner);
- kfree(idmap);
- }
-}
-
static struct mount *alloc_vfsmnt(const char *name)
{
struct mount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL);
}
EXPORT_SYMBOL(mntget);
+ /*
+ * Make a mount point inaccessible to new lookups.
+ * Because there may still be current users, the caller MUST WAIT
+ * for an RCU grace period before destroying the mount point.
+ */
+ void mnt_make_shortterm(struct vfsmount *mnt)
+ {
+ if (mnt)
+ real_mount(mnt)->mnt_ns = NULL;
+ }
+
/**
* path_is_mountpoint() - Check if path is a mount in the current namespace.
* @path: path to check
* Creating an idmapped mount with the filesystem wide idmapping
* doesn't make sense so block that. We don't allow mushy semantics.
*/
- if (mnt_idmap_owner(kattr->mnt_idmap) == fs_userns)
+ if (!check_fsmapping(kattr->mnt_idmap, m->mnt_sb))
return -EINVAL;
/*
* result.
*/
mnt_userns = container_of(ns, struct user_namespace, ns);
- if (initial_idmapping(mnt_userns)) {
+ if (mnt_userns == &init_user_ns) {
err = -EPERM;
goto out_fput;
}
void kern_unmount(struct vfsmount *mnt)
{
/* release long term mount so mount point can be released */
- if (!IS_ERR_OR_NULL(mnt)) {
- real_mount(mnt)->mnt_ns = NULL;
+ if (!IS_ERR(mnt)) {
+ mnt_make_shortterm(mnt);
synchronize_rcu(); /* yecchhh... */
mntput(mnt);
}
unsigned int i;
for (i = 0; i < num; i++)
- if (mnt[i])
- real_mount(mnt[i])->mnt_ns = NULL;
+ mnt_make_shortterm(mnt[i]);
synchronize_rcu_expedited();
for (i = 0; i < num; i++)
mntput(mnt[i]);
return error;
}
-static int mqueue_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int mqueue_create(struct mnt_idmap *idmap, struct inode *dir,
struct dentry *dentry, umode_t mode, bool excl)
{
return mqueue_create_attr(dentry, mode, NULL);
if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY))
return -EINVAL;
acc = oflag2acc[oflag & O_ACCMODE];
- return inode_permission(&init_user_ns, d_inode(dentry), acc);
+ return inode_permission(&nop_mnt_idmap, d_inode(dentry), acc);
}
static int do_mq_open(const char __user *u_name, int oflag, umode_t mode,
err = -ENOENT;
} else {
ihold(inode);
- err = vfs_unlink(&init_user_ns, d_inode(dentry->d_parent),
+ err = vfs_unlink(&nop_mnt_idmap, d_inode(dentry->d_parent),
dentry, NULL);
}
dput(dentry);
ns->mq_mnt->mnt_sb->s_fs_info = NULL;
}
- void mq_put_mnt(struct ipc_namespace *ns)
- {
- kern_unmount(ns->mq_mnt);
- }
-
static int __init init_mqueue_fs(void)
{
int error;
projects / linux-block.git / commitdiff