*/
#include <linux/syscalls.h>
-#include <linux/slab.h>
-#include <linux/sched.h>
-#include <linux/spinlock.h>
-#include <linux/percpu.h>
-#include <linux/init.h>
-#include <linux/kernel.h>
-#include <linux/acct.h>
+#include <linux/export.h>
#include <linux/capability.h>
-#include <linux/cpumask.h>
-#include <linux/module.h>
-#include <linux/sysfs.h>
-#include <linux/seq_file.h>
#include <linux/mnt_namespace.h>
+#include <linux/user_namespace.h>
#include <linux/namei.h>
-#include <linux/nsproxy.h>
#include <linux/security.h>
-#include <linux/mount.h>
-#include <linux/ramfs.h>
-#include <linux/log2.h>
#include <linux/idr.h>
-#include <linux/fs_struct.h>
-#include <linux/fsnotify.h>
-#include <asm/uaccess.h>
-#include <asm/unistd.h>
+#include <linux/acct.h> /* acct_auto_close_mnt */
+#include <linux/ramfs.h> /* init_rootfs */
+#include <linux/fs_struct.h> /* get_fs_root et.al. */
+#include <linux/fsnotify.h> /* fsnotify_vfsmount_delete */
+#include <linux/uaccess.h>
+#include <linux/proc_ns.h>
+#include <linux/magic.h>
#include "pnode.h"
#include "internal.h"
static int mnt_group_start = 1;
static struct list_head *mount_hashtable __read_mostly;
+static struct list_head *mountpoint_hashtable __read_mostly;
static struct kmem_cache *mnt_cache __read_mostly;
static struct rw_semaphore namespace_sem;
retry:
ida_pre_get(&mnt_id_ida, GFP_KERNEL);
spin_lock(&mnt_id_lock);
- res = ida_get_new_above(&mnt_id_ida, mnt_id_start, &mnt->mnt.mnt_id);
+ res = ida_get_new_above(&mnt_id_ida, mnt_id_start, &mnt->mnt_id);
if (!res)
- mnt_id_start = mnt->mnt.mnt_id + 1;
+ mnt_id_start = mnt->mnt_id + 1;
spin_unlock(&mnt_id_lock);
if (res == -EAGAIN)
goto retry;
static void mnt_free_id(struct mount *mnt)
{
- int id = mnt->mnt.mnt_id;
+ int id = mnt->mnt_id;
spin_lock(&mnt_id_lock);
ida_remove(&mnt_id_ida, id);
if (mnt_id_start > id)
res = ida_get_new_above(&mnt_group_ida,
mnt_group_start,
- &mnt->mnt.mnt_group_id);
+ &mnt->mnt_group_id);
if (!res)
- mnt_group_start = mnt->mnt.mnt_group_id + 1;
+ mnt_group_start = mnt->mnt_group_id + 1;
return res;
}
*/
void mnt_release_group_id(struct mount *mnt)
{
- int id = mnt->mnt.mnt_group_id;
+ int id = mnt->mnt_group_id;
ida_remove(&mnt_group_ida, id);
if (mnt_group_start > id)
mnt_group_start = id;
- mnt->mnt.mnt_group_id = 0;
+ mnt->mnt_group_id = 0;
}
/*
* vfsmount lock must be held for read
*/
-static inline void mnt_add_count(struct vfsmount *mnt, int n)
+static inline void mnt_add_count(struct mount *mnt, int n)
{
#ifdef CONFIG_SMP
this_cpu_add(mnt->mnt_pcp->mnt_count, n);
/*
* vfsmount lock must be held for write
*/
-unsigned int mnt_get_count(struct vfsmount *mnt)
+unsigned int mnt_get_count(struct mount *mnt)
{
#ifdef CONFIG_SMP
unsigned int count = 0;
static struct mount *alloc_vfsmnt(const char *name)
{
- struct mount *p = kmem_cache_zalloc(mnt_cache, GFP_KERNEL);
- if (p) {
- struct vfsmount *mnt = &p->mnt;
+ struct mount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL);
+ if (mnt) {
int err;
- err = mnt_alloc_id(p);
+ err = mnt_alloc_id(mnt);
if (err)
goto out_free_cache;
mnt->mnt_writers = 0;
#endif
- INIT_LIST_HEAD(&p->mnt_hash);
+ INIT_LIST_HEAD(&mnt->mnt_hash);
INIT_LIST_HEAD(&mnt->mnt_child);
INIT_LIST_HEAD(&mnt->mnt_mounts);
INIT_LIST_HEAD(&mnt->mnt_list);
INIT_HLIST_HEAD(&mnt->mnt_fsnotify_marks);
#endif
}
- return p;
+ return mnt;
#ifdef CONFIG_SMP
out_free_devname:
- kfree(p->mnt.mnt_devname);
+ kfree(mnt->mnt_devname);
#endif
out_free_id:
- mnt_free_id(p);
+ mnt_free_id(mnt);
out_free_cache:
- kmem_cache_free(mnt_cache, p);
+ kmem_cache_free(mnt_cache, mnt);
return NULL;
}
}
EXPORT_SYMBOL_GPL(__mnt_is_readonly);
-static inline void mnt_inc_writers(struct vfsmount *mnt)
+static inline void mnt_inc_writers(struct mount *mnt)
{
#ifdef CONFIG_SMP
this_cpu_inc(mnt->mnt_pcp->mnt_writers);
#endif
}
-static inline void mnt_dec_writers(struct vfsmount *mnt)
+static inline void mnt_dec_writers(struct mount *mnt)
{
#ifdef CONFIG_SMP
this_cpu_dec(mnt->mnt_pcp->mnt_writers);
#endif
}
-static unsigned int mnt_get_writers(struct vfsmount *mnt)
+static unsigned int mnt_get_writers(struct mount *mnt)
{
#ifdef CONFIG_SMP
unsigned int count = 0;
#endif
}
+static int mnt_is_readonly(struct vfsmount *mnt)
+{
+ if (mnt->mnt_sb->s_readonly_remount)
+ return 1;
+ /* Order wrt setting s_flags/s_readonly_remount in do_remount() */
+ smp_rmb();
+ return __mnt_is_readonly(mnt);
+}
+
/*
- * Most r/o checks on a fs are for operations that take
- * discrete amounts of time, like a write() or unlink().
- * We must keep track of when those operations start
- * (for permission checks) and when they end, so that
- * we can determine when writes are able to occur to
- * a filesystem.
+ * Most r/o & frozen checks on a fs are for operations that take discrete
+ * amounts of time, like a write() or unlink(). We must keep track of when
+ * those operations start (for permission checks) and when they end, so that we
+ * can determine when writes are able to occur to a filesystem.
*/
/**
- * mnt_want_write - get write access to a mount
- * @mnt: the mount on which to take a write
+ * __mnt_want_write - get write access to a mount without freeze protection
+ * @m: the mount on which to take a write
*
- * This tells the low-level filesystem that a write is
- * about to be performed to it, and makes sure that
- * writes are allowed before returning success. When
- * the write operation is finished, mnt_drop_write()
- * must be called. This is effectively a refcount.
+ * This tells the low-level filesystem that a write is about to be performed to
+ * it, and makes sure that writes are allowed (mnt it read-write) before
+ * returning success. This operation does not protect against filesystem being
+ * frozen. When the write operation is finished, __mnt_drop_write() must be
+ * called. This is effectively a refcount.
*/
-int mnt_want_write(struct vfsmount *mnt)
+int __mnt_want_write(struct vfsmount *m)
{
+ struct mount *mnt = real_mount(m);
int ret = 0;
preempt_disable();
* incremented count after it has set MNT_WRITE_HOLD.
*/
smp_mb();
- while (mnt->mnt_flags & MNT_WRITE_HOLD)
+ while (ACCESS_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD)
cpu_relax();
/*
* After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will
* MNT_WRITE_HOLD is cleared.
*/
smp_rmb();
- if (__mnt_is_readonly(mnt)) {
+ if (mnt_is_readonly(m)) {
mnt_dec_writers(mnt);
ret = -EROFS;
- goto out;
}
-out:
preempt_enable();
+
+ return ret;
+}
+
+/**
+ * mnt_want_write - get write access to a mount
+ * @m: the mount on which to take a write
+ *
+ * This tells the low-level filesystem that a write is about to be performed to
+ * it, and makes sure that writes are allowed (mount is read-write, filesystem
+ * is not frozen) before returning success. When the write operation is
+ * finished, mnt_drop_write() must be called. This is effectively a refcount.
+ */
+int mnt_want_write(struct vfsmount *m)
+{
+ int ret;
+
+ sb_start_write(m->mnt_sb);
+ ret = __mnt_want_write(m);
+ if (ret)
+ sb_end_write(m->mnt_sb);
return ret;
}
EXPORT_SYMBOL_GPL(mnt_want_write);
if (__mnt_is_readonly(mnt))
return -EROFS;
preempt_disable();
- mnt_inc_writers(mnt);
+ mnt_inc_writers(real_mount(mnt));
preempt_enable();
return 0;
}
EXPORT_SYMBOL_GPL(mnt_clone_write);
/**
- * mnt_want_write_file - get write access to a file's mount
+ * __mnt_want_write_file - get write access to a file's mount
* @file: the file who's mount on which to take a write
*
- * This is like mnt_want_write, but it takes a file and can
+ * This is like __mnt_want_write, but it takes a file and can
* do some optimisations if the file is open for write already
*/
-int mnt_want_write_file(struct file *file)
+int __mnt_want_write_file(struct file *file)
{
- struct inode *inode = file->f_dentry->d_inode;
+ struct inode *inode = file_inode(file);
+
if (!(file->f_mode & FMODE_WRITE) || special_file(inode->i_mode))
- return mnt_want_write(file->f_path.mnt);
+ return __mnt_want_write(file->f_path.mnt);
else
return mnt_clone_write(file->f_path.mnt);
}
+
+/**
+ * mnt_want_write_file - get write access to a file's mount
+ * @file: the file who's mount on which to take a write
+ *
+ * This is like mnt_want_write, but it takes a file and can
+ * do some optimisations if the file is open for write already
+ */
+int mnt_want_write_file(struct file *file)
+{
+ int ret;
+
+ sb_start_write(file->f_path.mnt->mnt_sb);
+ ret = __mnt_want_write_file(file);
+ if (ret)
+ sb_end_write(file->f_path.mnt->mnt_sb);
+ return ret;
+}
EXPORT_SYMBOL_GPL(mnt_want_write_file);
/**
- * mnt_drop_write - give up write access to a mount
+ * __mnt_drop_write - give up write access to a mount
* @mnt: the mount on which to give up write access
*
* Tells the low-level filesystem that we are done
* performing writes to it. Must be matched with
- * mnt_want_write() call above.
+ * __mnt_want_write() call above.
*/
-void mnt_drop_write(struct vfsmount *mnt)
+void __mnt_drop_write(struct vfsmount *mnt)
{
preempt_disable();
- mnt_dec_writers(mnt);
+ mnt_dec_writers(real_mount(mnt));
preempt_enable();
}
+
+/**
+ * mnt_drop_write - give up write access to a mount
+ * @mnt: the mount on which to give up write access
+ *
+ * Tells the low-level filesystem that we are done performing writes to it and
+ * also allows filesystem to be frozen again. Must be matched with
+ * mnt_want_write() call above.
+ */
+void mnt_drop_write(struct vfsmount *mnt)
+{
+ __mnt_drop_write(mnt);
+ sb_end_write(mnt->mnt_sb);
+}
EXPORT_SYMBOL_GPL(mnt_drop_write);
+void __mnt_drop_write_file(struct file *file)
+{
+ __mnt_drop_write(file->f_path.mnt);
+}
+
void mnt_drop_write_file(struct file *file)
{
mnt_drop_write(file->f_path.mnt);
}
EXPORT_SYMBOL(mnt_drop_write_file);
-static int mnt_make_readonly(struct vfsmount *mnt)
+static int mnt_make_readonly(struct mount *mnt)
{
int ret = 0;
- br_write_lock(vfsmount_lock);
- mnt->mnt_flags |= MNT_WRITE_HOLD;
+ br_write_lock(&vfsmount_lock);
+ mnt->mnt.mnt_flags |= MNT_WRITE_HOLD;
/*
* After storing MNT_WRITE_HOLD, we'll read the counters. This store
* should be visible before we do.
if (mnt_get_writers(mnt) > 0)
ret = -EBUSY;
else
- mnt->mnt_flags |= MNT_READONLY;
+ mnt->mnt.mnt_flags |= MNT_READONLY;
/*
* MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers
* that become unheld will see MNT_READONLY.
*/
smp_wmb();
- mnt->mnt_flags &= ~MNT_WRITE_HOLD;
- br_write_unlock(vfsmount_lock);
+ mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD;
+ br_write_unlock(&vfsmount_lock);
return ret;
}
-static void __mnt_unmake_readonly(struct vfsmount *mnt)
+static void __mnt_unmake_readonly(struct mount *mnt)
{
- br_write_lock(vfsmount_lock);
- mnt->mnt_flags &= ~MNT_READONLY;
- br_write_unlock(vfsmount_lock);
+ br_write_lock(&vfsmount_lock);
+ mnt->mnt.mnt_flags &= ~MNT_READONLY;
+ br_write_unlock(&vfsmount_lock);
+}
+
+int sb_prepare_remount_readonly(struct super_block *sb)
+{
+ struct mount *mnt;
+ int err = 0;
+
+ /* Racy optimization. Recheck the counter under MNT_WRITE_HOLD */
+ if (atomic_long_read(&sb->s_remove_count))
+ return -EBUSY;
+
+ br_write_lock(&vfsmount_lock);
+ list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) {
+ if (!(mnt->mnt.mnt_flags & MNT_READONLY)) {
+ mnt->mnt.mnt_flags |= MNT_WRITE_HOLD;
+ smp_mb();
+ if (mnt_get_writers(mnt) > 0) {
+ err = -EBUSY;
+ break;
+ }
+ }
+ }
+ if (!err && atomic_long_read(&sb->s_remove_count))
+ err = -EBUSY;
+
+ if (!err) {
+ sb->s_readonly_remount = 1;
+ smp_wmb();
+ }
+ list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) {
+ if (mnt->mnt.mnt_flags & MNT_WRITE_HOLD)
+ mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD;
+ }
+ br_write_unlock(&vfsmount_lock);
+
+ return err;
}
static void free_vfsmnt(struct mount *mnt)
{
- kfree(mnt->mnt.mnt_devname);
+ kfree(mnt->mnt_devname);
mnt_free_id(mnt);
#ifdef CONFIG_SMP
- free_percpu(mnt->mnt.mnt_pcp);
+ free_percpu(mnt->mnt_pcp);
#endif
kmem_cache_free(mnt_cache, mnt);
}
if (tmp == head)
break;
p = list_entry(tmp, struct mount, mnt_hash);
- if (p->mnt.mnt_parent == mnt && p->mnt.mnt_mountpoint == dentry) {
+ if (&p->mnt_parent->mnt == mnt && p->mnt_mountpoint == dentry) {
found = p;
break;
}
}
/*
- * lookup_mnt increments the ref count before returning
- * the vfsmount struct.
+ * lookup_mnt - Return the first child mount mounted at path
+ *
+ * "First" means first mounted chronologically. If you create the
+ * following mounts:
+ *
+ * mount /dev/sda1 /mnt
+ * mount /dev/sda2 /mnt
+ * mount /dev/sda3 /mnt
+ *
+ * Then lookup_mnt() on the base /mnt dentry in the root mount will
+ * return successively the root dentry and vfsmount of /dev/sda1, then
+ * /dev/sda2, then /dev/sda3, then NULL.
+ *
+ * lookup_mnt takes a reference to the found vfsmount.
*/
struct vfsmount *lookup_mnt(struct path *path)
{
struct mount *child_mnt;
- br_read_lock(vfsmount_lock);
+ br_read_lock(&vfsmount_lock);
child_mnt = __lookup_mnt(path->mnt, path->dentry, 1);
if (child_mnt) {
mnt_add_count(child_mnt, 1);
- br_read_unlock(vfsmount_lock);
+ br_read_unlock(&vfsmount_lock);
return &child_mnt->mnt;
} else {
- br_read_unlock(vfsmount_lock);
+ br_read_unlock(&vfsmount_lock);
return NULL;
}
}
-static inline int check_mnt(struct vfsmount *mnt)
+static struct mountpoint *new_mountpoint(struct dentry *dentry)
+{
+ struct list_head *chain = mountpoint_hashtable + hash(NULL, dentry);
+ struct mountpoint *mp;
+
+ list_for_each_entry(mp, chain, m_hash) {
+ if (mp->m_dentry == dentry) {
+ /* might be worth a WARN_ON() */
+ if (d_unlinked(dentry))
+ return ERR_PTR(-ENOENT);
+ mp->m_count++;
+ return mp;
+ }
+ }
+
+ mp = kmalloc(sizeof(struct mountpoint), GFP_KERNEL);
+ if (!mp)
+ return ERR_PTR(-ENOMEM);
+
+ spin_lock(&dentry->d_lock);
+ if (d_unlinked(dentry)) {
+ spin_unlock(&dentry->d_lock);
+ kfree(mp);
+ return ERR_PTR(-ENOENT);
+ }
+ dentry->d_flags |= DCACHE_MOUNTED;
+ spin_unlock(&dentry->d_lock);
+ mp->m_dentry = dentry;
+ mp->m_count = 1;
+ list_add(&mp->m_hash, chain);
+ return mp;
+}
+
+static void put_mountpoint(struct mountpoint *mp)
+{
+ if (!--mp->m_count) {
+ struct dentry *dentry = mp->m_dentry;
+ spin_lock(&dentry->d_lock);
+ dentry->d_flags &= ~DCACHE_MOUNTED;
+ spin_unlock(&dentry->d_lock);
+ list_del(&mp->m_hash);
+ kfree(mp);
+ }
+}
+
+static inline int check_mnt(struct mount *mnt)
{
return mnt->mnt_ns == current->nsproxy->mnt_ns;
}
}
/*
- * Clear dentry's mounted state if it has no remaining mounts.
- * vfsmount_lock must be held for write.
- */
-static void dentry_reset_mounted(struct dentry *dentry)
-{
- unsigned u;
-
- for (u = 0; u < HASH_SIZE; u++) {
- struct mount *p;
-
- list_for_each_entry(p, &mount_hashtable[u], mnt_hash) {
- if (p->mnt.mnt_mountpoint == dentry)
- return;
- }
- }
- spin_lock(&dentry->d_lock);
- dentry->d_flags &= ~DCACHE_MOUNTED;
- spin_unlock(&dentry->d_lock);
-}
-
-/*
* vfsmount lock must be held for write
*/
static void detach_mnt(struct mount *mnt, struct path *old_path)
{
- old_path->dentry = mnt->mnt.mnt_mountpoint;
- old_path->mnt = mnt->mnt.mnt_parent;
- mnt->mnt.mnt_parent = &mnt->mnt;
- mnt->mnt.mnt_mountpoint = mnt->mnt.mnt_root;
- list_del_init(&mnt->mnt.mnt_child);
+ old_path->dentry = mnt->mnt_mountpoint;
+ old_path->mnt = &mnt->mnt_parent->mnt;
+ mnt->mnt_parent = mnt;
+ mnt->mnt_mountpoint = mnt->mnt.mnt_root;
+ list_del_init(&mnt->mnt_child);
list_del_init(&mnt->mnt_hash);
- dentry_reset_mounted(old_path->dentry);
+ put_mountpoint(mnt->mnt_mp);
+ mnt->mnt_mp = NULL;
}
/*
* vfsmount lock must be held for write
*/
-void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry,
+void mnt_set_mountpoint(struct mount *mnt,
+ struct mountpoint *mp,
struct mount *child_mnt)
{
- child_mnt->mnt.mnt_parent = mntget(mnt);
- child_mnt->mnt.mnt_mountpoint = dget(dentry);
- spin_lock(&dentry->d_lock);
- dentry->d_flags |= DCACHE_MOUNTED;
- spin_unlock(&dentry->d_lock);
+ mp->m_count++;
+ mnt_add_count(mnt, 1); /* essentially, that's mntget */
+ child_mnt->mnt_mountpoint = dget(mp->m_dentry);
+ child_mnt->mnt_parent = mnt;
+ child_mnt->mnt_mp = mp;
}
/*
* vfsmount lock must be held for write
*/
-static void attach_mnt(struct mount *mnt, struct path *path)
+static void attach_mnt(struct mount *mnt,
+ struct mount *parent,
+ struct mountpoint *mp)
{
- mnt_set_mountpoint(path->mnt, path->dentry, mnt);
+ mnt_set_mountpoint(parent, mp, mnt);
list_add_tail(&mnt->mnt_hash, mount_hashtable +
- hash(path->mnt, path->dentry));
- list_add_tail(&mnt->mnt.mnt_child, &path->mnt->mnt_mounts);
-}
-
-static inline void __mnt_make_longterm(struct vfsmount *mnt)
-{
-#ifdef CONFIG_SMP
- atomic_inc(&mnt->mnt_longterm);
-#endif
-}
-
-/* needs vfsmount lock for write */
-static inline void __mnt_make_shortterm(struct vfsmount *mnt)
-{
-#ifdef CONFIG_SMP
- atomic_dec(&mnt->mnt_longterm);
-#endif
+ hash(&parent->mnt, mp->m_dentry));
+ list_add_tail(&mnt->mnt_child, &parent->mnt_mounts);
}
/*
*/
static void commit_tree(struct mount *mnt)
{
- struct vfsmount *parent = mnt->mnt.mnt_parent;
- struct vfsmount *m;
+ struct mount *parent = mnt->mnt_parent;
+ struct mount *m;
LIST_HEAD(head);
struct mnt_namespace *n = parent->mnt_ns;
- BUG_ON(parent == &mnt->mnt);
+ BUG_ON(parent == mnt);
- list_add_tail(&head, &mnt->mnt.mnt_list);
- list_for_each_entry(m, &head, mnt_list) {
+ list_add_tail(&head, &mnt->mnt_list);
+ list_for_each_entry(m, &head, mnt_list)
m->mnt_ns = n;
- __mnt_make_longterm(m);
- }
list_splice(&head, n->list.prev);
list_add_tail(&mnt->mnt_hash, mount_hashtable +
- hash(parent, mnt->mnt.mnt_mountpoint));
- list_add_tail(&mnt->mnt.mnt_child, &parent->mnt_mounts);
+ hash(&parent->mnt, mnt->mnt_mountpoint));
+ list_add_tail(&mnt->mnt_child, &parent->mnt_mounts);
touch_mnt_namespace(n);
}
-static struct mount *next_mnt(struct mount *p, struct vfsmount *root)
+static struct mount *next_mnt(struct mount *p, struct mount *root)
{
- struct list_head *next = p->mnt.mnt_mounts.next;
- if (next == &p->mnt.mnt_mounts) {
+ struct list_head *next = p->mnt_mounts.next;
+ if (next == &p->mnt_mounts) {
while (1) {
- if (&p->mnt == root)
+ if (p == root)
return NULL;
- next = p->mnt.mnt_child.next;
- if (next != &p->mnt.mnt_parent->mnt_mounts)
+ next = p->mnt_child.next;
+ if (next != &p->mnt_parent->mnt_mounts)
break;
- p = real_mount(p->mnt.mnt_parent);
+ p = p->mnt_parent;
}
}
- return list_entry(next, struct mount, mnt.mnt_child);
+ return list_entry(next, struct mount, mnt_child);
}
static struct mount *skip_mnt_tree(struct mount *p)
{
- struct list_head *prev = p->mnt.mnt_mounts.prev;
- while (prev != &p->mnt.mnt_mounts) {
- p = list_entry(prev, struct mount, mnt.mnt_child);
- prev = p->mnt.mnt_mounts.prev;
+ struct list_head *prev = p->mnt_mounts.prev;
+ while (prev != &p->mnt_mounts) {
+ p = list_entry(prev, struct mount, mnt_child);
+ prev = p->mnt_mounts.prev;
}
return p;
}
mnt->mnt.mnt_root = root;
mnt->mnt.mnt_sb = root->d_sb;
- mnt->mnt.mnt_mountpoint = mnt->mnt.mnt_root;
- mnt->mnt.mnt_parent = &mnt->mnt;
+ mnt->mnt_mountpoint = mnt->mnt.mnt_root;
+ mnt->mnt_parent = mnt;
+ br_write_lock(&vfsmount_lock);
+ list_add_tail(&mnt->mnt_instance, &root->d_sb->s_mounts);
+ br_write_unlock(&vfsmount_lock);
return &mnt->mnt;
}
EXPORT_SYMBOL_GPL(vfs_kern_mount);
int flag)
{
struct super_block *sb = old->mnt.mnt_sb;
- struct mount *mnt = alloc_vfsmnt(old->mnt.mnt_devname);
+ struct mount *mnt;
+ int err;
- if (mnt) {
- if (flag & (CL_SLAVE | CL_PRIVATE))
- mnt->mnt.mnt_group_id = 0; /* not a peer of original */
- else
- mnt->mnt.mnt_group_id = old->mnt.mnt_group_id;
-
- if ((flag & CL_MAKE_SHARED) && !mnt->mnt.mnt_group_id) {
- int err = mnt_alloc_group_id(mnt);
- if (err)
- goto out_free;
- }
+ mnt = alloc_vfsmnt(old->mnt_devname);
+ if (!mnt)
+ return ERR_PTR(-ENOMEM);
- mnt->mnt.mnt_flags = old->mnt.mnt_flags & ~MNT_WRITE_HOLD;
- atomic_inc(&sb->s_active);
- mnt->mnt.mnt_sb = sb;
- mnt->mnt.mnt_root = dget(root);
- mnt->mnt.mnt_mountpoint = mnt->mnt.mnt_root;
- mnt->mnt.mnt_parent = &mnt->mnt;
-
- if (flag & CL_SLAVE) {
- list_add(&mnt->mnt.mnt_slave, &old->mnt.mnt_slave_list);
- mnt->mnt.mnt_master = &old->mnt;
- CLEAR_MNT_SHARED(&mnt->mnt);
- } else if (!(flag & CL_PRIVATE)) {
- if ((flag & CL_MAKE_SHARED) || IS_MNT_SHARED(&old->mnt))
- list_add(&mnt->mnt.mnt_share, &old->mnt.mnt_share);
- if (IS_MNT_SLAVE(&old->mnt))
- list_add(&mnt->mnt.mnt_slave, &old->mnt.mnt_slave);
- mnt->mnt.mnt_master = old->mnt.mnt_master;
- }
- if (flag & CL_MAKE_SHARED)
- set_mnt_shared(mnt);
-
- /* stick the duplicate mount on the same expiry list
- * as the original if that was on one */
- if (flag & CL_EXPIRE) {
- if (!list_empty(&old->mnt.mnt_expire))
- list_add(&mnt->mnt.mnt_expire, &old->mnt.mnt_expire);
- }
+ if (flag & (CL_SLAVE | CL_PRIVATE | CL_SHARED_TO_SLAVE))
+ mnt->mnt_group_id = 0; /* not a peer of original */
+ else
+ mnt->mnt_group_id = old->mnt_group_id;
+
+ if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) {
+ err = mnt_alloc_group_id(mnt);
+ if (err)
+ goto out_free;
}
+
+ mnt->mnt.mnt_flags = old->mnt.mnt_flags & ~MNT_WRITE_HOLD;
+ /* Don't allow unprivileged users to change mount flags */
+ if (flag & CL_UNPRIVILEGED) {
+ mnt->mnt.mnt_flags |= MNT_LOCK_ATIME;
+
+ if (mnt->mnt.mnt_flags & MNT_READONLY)
+ mnt->mnt.mnt_flags |= MNT_LOCK_READONLY;
+
+ if (mnt->mnt.mnt_flags & MNT_NODEV)
+ mnt->mnt.mnt_flags |= MNT_LOCK_NODEV;
+
+ if (mnt->mnt.mnt_flags & MNT_NOSUID)
+ mnt->mnt.mnt_flags |= MNT_LOCK_NOSUID;
+
+ if (mnt->mnt.mnt_flags & MNT_NOEXEC)
+ mnt->mnt.mnt_flags |= MNT_LOCK_NOEXEC;
+ }
+
+ atomic_inc(&sb->s_active);
+ mnt->mnt.mnt_sb = sb;
+ mnt->mnt.mnt_root = dget(root);
+ mnt->mnt_mountpoint = mnt->mnt.mnt_root;
+ mnt->mnt_parent = mnt;
+ br_write_lock(&vfsmount_lock);
+ list_add_tail(&mnt->mnt_instance, &sb->s_mounts);
+ br_write_unlock(&vfsmount_lock);
+
+ if ((flag & CL_SLAVE) ||
+ ((flag & CL_SHARED_TO_SLAVE) && IS_MNT_SHARED(old))) {
+ list_add(&mnt->mnt_slave, &old->mnt_slave_list);
+ mnt->mnt_master = old;
+ CLEAR_MNT_SHARED(mnt);
+ } else if (!(flag & CL_PRIVATE)) {
+ if ((flag & CL_MAKE_SHARED) || IS_MNT_SHARED(old))
+ list_add(&mnt->mnt_share, &old->mnt_share);
+ if (IS_MNT_SLAVE(old))
+ list_add(&mnt->mnt_slave, &old->mnt_slave);
+ mnt->mnt_master = old->mnt_master;
+ }
+ if (flag & CL_MAKE_SHARED)
+ set_mnt_shared(mnt);
+
+ /* stick the duplicate mount on the same expiry list
+ * as the original if that was on one */
+ if (flag & CL_EXPIRE) {
+ if (!list_empty(&old->mnt_expire))
+ list_add(&mnt->mnt_expire, &old->mnt_expire);
+ }
+
return mnt;
out_free:
free_vfsmnt(mnt);
- return NULL;
+ return ERR_PTR(err);
}
-static inline void mntfree(struct vfsmount *mnt)
+static inline void mntfree(struct mount *mnt)
{
- struct super_block *sb = mnt->mnt_sb;
+ struct vfsmount *m = &mnt->mnt;
+ struct super_block *sb = m->mnt_sb;
/*
* This probably indicates that somebody messed
* so mnt_get_writers() below is safe.
*/
WARN_ON(mnt_get_writers(mnt));
- fsnotify_vfsmount_delete(mnt);
- dput(mnt->mnt_root);
- free_vfsmnt(real_mount(mnt));
+ fsnotify_vfsmount_delete(m);
+ dput(m->mnt_root);
+ free_vfsmnt(mnt);
deactivate_super(sb);
}
-static void mntput_no_expire(struct vfsmount *mnt)
+static void mntput_no_expire(struct mount *mnt)
{
put_again:
#ifdef CONFIG_SMP
- br_read_lock(vfsmount_lock);
- if (likely(atomic_read(&mnt->mnt_longterm))) {
+ br_read_lock(&vfsmount_lock);
+ if (likely(mnt->mnt_ns)) {
+ /* shouldn't be the last one */
mnt_add_count(mnt, -1);
- br_read_unlock(vfsmount_lock);
+ br_read_unlock(&vfsmount_lock);
return;
}
- br_read_unlock(vfsmount_lock);
+ br_read_unlock(&vfsmount_lock);
- br_write_lock(vfsmount_lock);
+ br_write_lock(&vfsmount_lock);
mnt_add_count(mnt, -1);
if (mnt_get_count(mnt)) {
- br_write_unlock(vfsmount_lock);
+ br_write_unlock(&vfsmount_lock);
return;
}
#else
mnt_add_count(mnt, -1);
if (likely(mnt_get_count(mnt)))
return;
- br_write_lock(vfsmount_lock);
+ br_write_lock(&vfsmount_lock);
#endif
if (unlikely(mnt->mnt_pinned)) {
mnt_add_count(mnt, mnt->mnt_pinned + 1);
mnt->mnt_pinned = 0;
- br_write_unlock(vfsmount_lock);
- acct_auto_close_mnt(mnt);
+ br_write_unlock(&vfsmount_lock);
+ acct_auto_close_mnt(&mnt->mnt);
goto put_again;
}
- br_write_unlock(vfsmount_lock);
+
+ list_del(&mnt->mnt_instance);
+ br_write_unlock(&vfsmount_lock);
mntfree(mnt);
}
void mntput(struct vfsmount *mnt)
{
if (mnt) {
+ struct mount *m = real_mount(mnt);
/* avoid cacheline pingpong, hope gcc doesn't get "smart" */
- if (unlikely(mnt->mnt_expiry_mark))
- mnt->mnt_expiry_mark = 0;
- mntput_no_expire(mnt);
+ if (unlikely(m->mnt_expiry_mark))
+ m->mnt_expiry_mark = 0;
+ mntput_no_expire(m);
}
}
EXPORT_SYMBOL(mntput);
struct vfsmount *mntget(struct vfsmount *mnt)
{
if (mnt)
- mnt_add_count(mnt, 1);
+ mnt_add_count(real_mount(mnt), 1);
return mnt;
}
EXPORT_SYMBOL(mntget);
void mnt_pin(struct vfsmount *mnt)
{
- br_write_lock(vfsmount_lock);
- mnt->mnt_pinned++;
- br_write_unlock(vfsmount_lock);
+ br_write_lock(&vfsmount_lock);
+ real_mount(mnt)->mnt_pinned++;
+ br_write_unlock(&vfsmount_lock);
}
EXPORT_SYMBOL(mnt_pin);
-void mnt_unpin(struct vfsmount *mnt)
+void mnt_unpin(struct vfsmount *m)
{
- br_write_lock(vfsmount_lock);
+ struct mount *mnt = real_mount(m);
+ br_write_lock(&vfsmount_lock);
if (mnt->mnt_pinned) {
mnt_add_count(mnt, 1);
mnt->mnt_pinned--;
}
- br_write_unlock(vfsmount_lock);
+ br_write_unlock(&vfsmount_lock);
}
EXPORT_SYMBOL(mnt_unpin);
*
* See also save_mount_options().
*/
-int generic_show_options(struct seq_file *m, struct vfsmount *mnt)
+int generic_show_options(struct seq_file *m, struct dentry *root)
{
const char *options;
rcu_read_lock();
- options = rcu_dereference(mnt->mnt_sb->s_options);
+ options = rcu_dereference(root->d_sb->s_options);
if (options != NULL && options[0]) {
seq_putc(m, ',');
EXPORT_SYMBOL(replace_mount_options);
#ifdef CONFIG_PROC_FS
-/* iterator */
+/* iterator; we want it to have access to namespace_sem, thus here... */
static void *m_start(struct seq_file *m, loff_t *pos)
{
- struct proc_mounts *p = m->private;
+ struct proc_mounts *p = proc_mounts(m);
down_read(&namespace_sem);
return seq_list_start(&p->ns->list, *pos);
static void *m_next(struct seq_file *m, void *v, loff_t *pos)
{
- struct proc_mounts *p = m->private;
+ struct proc_mounts *p = proc_mounts(m);
return seq_list_next(v, &p->ns->list, pos);
}
up_read(&namespace_sem);
}
-int mnt_had_events(struct proc_mounts *p)
-{
- struct mnt_namespace *ns = p->ns;
- int res = 0;
-
- br_read_lock(vfsmount_lock);
- if (p->m.poll_event != ns->event) {
- p->m.poll_event = ns->event;
- res = 1;
- }
- br_read_unlock(vfsmount_lock);
-
- return res;
-}
-
-struct proc_fs_info {
- int flag;
- const char *str;
-};
-
-static int show_sb_opts(struct seq_file *m, struct super_block *sb)
-{
- static const struct proc_fs_info fs_info[] = {
- { MS_SYNCHRONOUS, ",sync" },
- { MS_DIRSYNC, ",dirsync" },
- { MS_MANDLOCK, ",mand" },
- { 0, NULL }
- };
- const struct proc_fs_info *fs_infop;
-
- for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
- if (sb->s_flags & fs_infop->flag)
- seq_puts(m, fs_infop->str);
- }
-
- return security_sb_show_options(m, sb);
-}
-
-static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt)
-{
- static const struct proc_fs_info mnt_info[] = {
- { MNT_NOSUID, ",nosuid" },
- { MNT_NODEV, ",nodev" },
- { MNT_NOEXEC, ",noexec" },
- { MNT_NOATIME, ",noatime" },
- { MNT_NODIRATIME, ",nodiratime" },
- { MNT_RELATIME, ",relatime" },
- { 0, NULL }
- };
- const struct proc_fs_info *fs_infop;
-
- for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) {
- if (mnt->mnt_flags & fs_infop->flag)
- seq_puts(m, fs_infop->str);
- }
-}
-
-static void show_type(struct seq_file *m, struct super_block *sb)
+static int m_show(struct seq_file *m, void *v)
{
- mangle(m, sb->s_type->name);
- if (sb->s_subtype && sb->s_subtype[0]) {
- seq_putc(m, '.');
- mangle(m, sb->s_subtype);
- }
-}
-
-static int show_vfsmnt(struct seq_file *m, void *v)
-{
- struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list);
- int err = 0;
- struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
-
- if (mnt->mnt_sb->s_op->show_devname) {
- err = mnt->mnt_sb->s_op->show_devname(m, mnt);
- if (err)
- goto out;
- } else {
- mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
- }
- seq_putc(m, ' ');
- seq_path(m, &mnt_path, " \t\n\\");
- seq_putc(m, ' ');
- show_type(m, mnt->mnt_sb);
- seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
- err = show_sb_opts(m, mnt->mnt_sb);
- if (err)
- goto out;
- show_mnt_opts(m, mnt);
- if (mnt->mnt_sb->s_op->show_options)
- err = mnt->mnt_sb->s_op->show_options(m, mnt);
- seq_puts(m, " 0 0\n");
-out:
- return err;
+ struct proc_mounts *p = proc_mounts(m);
+ struct mount *r = list_entry(v, struct mount, mnt_list);
+ return p->show(m, &r->mnt);
}
const struct seq_operations mounts_op = {
.start = m_start,
.next = m_next,
.stop = m_stop,
- .show = show_vfsmnt
-};
-
-static int show_mountinfo(struct seq_file *m, void *v)
-{
- struct proc_mounts *p = m->private;
- struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list);
- struct super_block *sb = mnt->mnt_sb;
- struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
- struct path root = p->root;
- int err = 0;
-
- seq_printf(m, "%i %i %u:%u ", mnt->mnt_id, mnt->mnt_parent->mnt_id,
- MAJOR(sb->s_dev), MINOR(sb->s_dev));
- if (sb->s_op->show_path)
- err = sb->s_op->show_path(m, mnt);
- else
- seq_dentry(m, mnt->mnt_root, " \t\n\\");
- if (err)
- goto out;
- seq_putc(m, ' ');
-
- /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
- err = seq_path_root(m, &mnt_path, &root, " \t\n\\");
- if (err)
- goto out;
-
- seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
- show_mnt_opts(m, mnt);
-
- /* Tagged fields ("foo:X" or "bar") */
- if (IS_MNT_SHARED(mnt))
- seq_printf(m, " shared:%i", mnt->mnt_group_id);
- if (IS_MNT_SLAVE(mnt)) {
- int master = mnt->mnt_master->mnt_group_id;
- int dom = get_dominating_id(mnt, &p->root);
- seq_printf(m, " master:%i", master);
- if (dom && dom != master)
- seq_printf(m, " propagate_from:%i", dom);
- }
- if (IS_MNT_UNBINDABLE(mnt))
- seq_puts(m, " unbindable");
-
- /* Filesystem specific data */
- seq_puts(m, " - ");
- show_type(m, sb);
- seq_putc(m, ' ');
- if (sb->s_op->show_devname)
- err = sb->s_op->show_devname(m, mnt);
- else
- mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
- if (err)
- goto out;
- seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw");
- err = show_sb_opts(m, sb);
- if (err)
- goto out;
- if (sb->s_op->show_options)
- err = sb->s_op->show_options(m, mnt);
- seq_putc(m, '\n');
-out:
- return err;
-}
-
-const struct seq_operations mountinfo_op = {
- .start = m_start,
- .next = m_next,
- .stop = m_stop,
- .show = show_mountinfo,
-};
-
-static int show_vfsstat(struct seq_file *m, void *v)
-{
- struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list);
- struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
- int err = 0;
-
- /* device */
- if (mnt->mnt_sb->s_op->show_devname) {
- seq_puts(m, "device ");
- err = mnt->mnt_sb->s_op->show_devname(m, mnt);
- } else {
- if (mnt->mnt_devname) {
- seq_puts(m, "device ");
- mangle(m, mnt->mnt_devname);
- } else
- seq_puts(m, "no device");
- }
-
- /* mount point */
- seq_puts(m, " mounted on ");
- seq_path(m, &mnt_path, " \t\n\\");
- seq_putc(m, ' ');
-
- /* file system type */
- seq_puts(m, "with fstype ");
- show_type(m, mnt->mnt_sb);
-
- /* optional statistics */
- if (mnt->mnt_sb->s_op->show_stats) {
- seq_putc(m, ' ');
- if (!err)
- err = mnt->mnt_sb->s_op->show_stats(m, mnt);
- }
-
- seq_putc(m, '\n');
- return err;
-}
-
-const struct seq_operations mountstats_op = {
- .start = m_start,
- .next = m_next,
- .stop = m_stop,
- .show = show_vfsstat,
+ .show = m_show,
};
#endif /* CONFIG_PROC_FS */
* open files, pwds, chroots or sub mounts that are
* busy.
*/
-int may_umount_tree(struct vfsmount *mnt)
+int may_umount_tree(struct vfsmount *m)
{
+ struct mount *mnt = real_mount(m);
int actual_refs = 0;
int minimum_refs = 0;
struct mount *p;
- BUG_ON(!mnt);
+ BUG_ON(!m);
/* write lock needed for mnt_get_count */
- br_write_lock(vfsmount_lock);
- for (p = real_mount(mnt); p; p = next_mnt(p, mnt)) {
- actual_refs += mnt_get_count(&p->mnt);
+ br_write_lock(&vfsmount_lock);
+ for (p = mnt; p; p = next_mnt(p, mnt)) {
+ actual_refs += mnt_get_count(p);
minimum_refs += 2;
}
- br_write_unlock(vfsmount_lock);
+ br_write_unlock(&vfsmount_lock);
if (actual_refs > minimum_refs)
return 0;
{
int ret = 1;
down_read(&namespace_sem);
- br_write_lock(vfsmount_lock);
- if (propagate_mount_busy(mnt, 2))
+ br_write_lock(&vfsmount_lock);
+ if (propagate_mount_busy(real_mount(mnt), 2))
ret = 0;
- br_write_unlock(vfsmount_lock);
+ br_write_unlock(&vfsmount_lock);
up_read(&namespace_sem);
return ret;
}
EXPORT_SYMBOL(may_umount);
-void release_mounts(struct list_head *head)
+static LIST_HEAD(unmounted); /* protected by namespace_sem */
+
+static void namespace_unlock(void)
{
struct mount *mnt;
- while (!list_empty(head)) {
- mnt = list_first_entry(head, struct mount, mnt_hash);
+ LIST_HEAD(head);
+
+ if (likely(list_empty(&unmounted))) {
+ up_write(&namespace_sem);
+ return;
+ }
+
+ list_splice_init(&unmounted, &head);
+ up_write(&namespace_sem);
+
+ while (!list_empty(&head)) {
+ mnt = list_first_entry(&head, struct mount, mnt_hash);
list_del_init(&mnt->mnt_hash);
- if (mnt_has_parent(&mnt->mnt)) {
+ if (mnt_has_parent(mnt)) {
struct dentry *dentry;
- struct vfsmount *m;
+ struct mount *m;
- br_write_lock(vfsmount_lock);
- dentry = mnt->mnt.mnt_mountpoint;
- m = mnt->mnt.mnt_parent;
- mnt->mnt.mnt_mountpoint = mnt->mnt.mnt_root;
- mnt->mnt.mnt_parent = &mnt->mnt;
+ br_write_lock(&vfsmount_lock);
+ dentry = mnt->mnt_mountpoint;
+ m = mnt->mnt_parent;
+ mnt->mnt_mountpoint = mnt->mnt.mnt_root;
+ mnt->mnt_parent = mnt;
m->mnt_ghosts--;
- br_write_unlock(vfsmount_lock);
+ br_write_unlock(&vfsmount_lock);
dput(dentry);
- mntput(m);
+ mntput(&m->mnt);
}
mntput(&mnt->mnt);
}
}
+static inline void namespace_lock(void)
+{
+ down_write(&namespace_sem);
+}
+
/*
* vfsmount lock must be held for write
* namespace_sem must be held for write
*/
-void umount_tree(struct mount *mnt, int propagate, struct list_head *kill)
+void umount_tree(struct mount *mnt, int propagate)
{
LIST_HEAD(tmp_list);
struct mount *p;
- for (p = mnt; p; p = next_mnt(p, &mnt->mnt))
+ for (p = mnt; p; p = next_mnt(p, mnt))
list_move(&p->mnt_hash, &tmp_list);
if (propagate)
propagate_umount(&tmp_list);
list_for_each_entry(p, &tmp_list, mnt_hash) {
- list_del_init(&p->mnt.mnt_expire);
- list_del_init(&p->mnt.mnt_list);
- __touch_mnt_namespace(p->mnt.mnt_ns);
- p->mnt.mnt_ns = NULL;
- __mnt_make_shortterm(&p->mnt);
- list_del_init(&p->mnt.mnt_child);
- if (mnt_has_parent(&p->mnt)) {
- p->mnt.mnt_parent->mnt_ghosts++;
- dentry_reset_mounted(p->mnt.mnt_mountpoint);
+ list_del_init(&p->mnt_expire);
+ list_del_init(&p->mnt_list);
+ __touch_mnt_namespace(p->mnt_ns);
+ p->mnt_ns = NULL;
+ list_del_init(&p->mnt_child);
+ if (mnt_has_parent(p)) {
+ p->mnt_parent->mnt_ghosts++;
+ put_mountpoint(p->mnt_mp);
+ p->mnt_mp = NULL;
}
change_mnt_propagation(p, MS_PRIVATE);
}
- list_splice(&tmp_list, kill);
+ list_splice(&tmp_list, &unmounted);
}
-static void shrink_submounts(struct mount *mnt, struct list_head *umounts);
+static void shrink_submounts(struct mount *mnt);
-static int do_umount(struct vfsmount *mnt, int flags)
+static int do_umount(struct mount *mnt, int flags)
{
- struct super_block *sb = mnt->mnt_sb;
+ struct super_block *sb = mnt->mnt.mnt_sb;
int retval;
- LIST_HEAD(umount_list);
- retval = security_sb_umount(mnt, flags);
+ retval = security_sb_umount(&mnt->mnt, flags);
if (retval)
return retval;
* (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount]
*/
if (flags & MNT_EXPIRE) {
- if (mnt == current->fs->root.mnt ||
+ if (&mnt->mnt == current->fs->root.mnt ||
flags & (MNT_FORCE | MNT_DETACH))
return -EINVAL;
* probably don't strictly need the lock here if we examined
* all race cases, but it's a slowpath.
*/
- br_write_lock(vfsmount_lock);
+ br_write_lock(&vfsmount_lock);
if (mnt_get_count(mnt) != 2) {
- br_write_unlock(vfsmount_lock);
+ br_write_unlock(&vfsmount_lock);
return -EBUSY;
}
- br_write_unlock(vfsmount_lock);
+ br_write_unlock(&vfsmount_lock);
if (!xchg(&mnt->mnt_expiry_mark, 1))
return -EAGAIN;
* /reboot - static binary that would close all descriptors and
* call reboot(9). Then init(8) could umount root and exec /reboot.
*/
- if (mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) {
+ if (&mnt->mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) {
/*
* Special case for "unmounting" root ...
* we just try to remount it readonly.
*/
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
down_write(&sb->s_umount);
if (!(sb->s_flags & MS_RDONLY))
retval = do_remount_sb(sb, MS_RDONLY, NULL, 0);
return retval;
}
- down_write(&namespace_sem);
- br_write_lock(vfsmount_lock);
+ namespace_lock();
+ br_write_lock(&vfsmount_lock);
event++;
if (!(flags & MNT_DETACH))
- shrink_submounts(real_mount(mnt), &umount_list);
+ shrink_submounts(mnt);
retval = -EBUSY;
if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) {
if (!list_empty(&mnt->mnt_list))
- umount_tree(real_mount(mnt), 1, &umount_list);
+ umount_tree(mnt, 1);
retval = 0;
}
- br_write_unlock(vfsmount_lock);
- up_write(&namespace_sem);
- release_mounts(&umount_list);
+ br_write_unlock(&vfsmount_lock);
+ namespace_unlock();
return retval;
}
+/*
+ * Is the caller allowed to modify his namespace?
+ */
+static inline bool may_mount(void)
+{
+ return ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN);
+}
+
/*
* Now umount can handle mount points as well as block devices.
* This is important for filesystems which use unnamed block devices.
SYSCALL_DEFINE2(umount, char __user *, name, int, flags)
{
struct path path;
+ struct mount *mnt;
int retval;
int lookup_flags = 0;
if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW))
return -EINVAL;
+ if (!may_mount())
+ return -EPERM;
+
if (!(flags & UMOUNT_NOFOLLOW))
lookup_flags |= LOOKUP_FOLLOW;
retval = user_path_at(AT_FDCWD, name, lookup_flags, &path);
if (retval)
goto out;
+ mnt = real_mount(path.mnt);
retval = -EINVAL;
if (path.dentry != path.mnt->mnt_root)
goto dput_and_out;
- if (!check_mnt(path.mnt))
+ if (!check_mnt(mnt))
goto dput_and_out;
-
retval = -EPERM;
- if (!capable(CAP_SYS_ADMIN))
+ if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN))
goto dput_and_out;
- retval = do_umount(path.mnt, flags);
+ retval = do_umount(mnt, flags);
dput_and_out:
/* we mustn't call path_put() as that would clear mnt_expiry_mark */
dput(path.dentry);
- mntput_no_expire(path.mnt);
+ mntput_no_expire(mnt);
out:
return retval;
}
#endif
-static int mount_is_safe(struct path *path)
+static bool mnt_ns_loop(struct path *path)
{
- if (capable(CAP_SYS_ADMIN))
- return 0;
- return -EPERM;
-#ifdef notyet
- if (S_ISLNK(path->dentry->d_inode->i_mode))
- return -EPERM;
- if (path->dentry->d_inode->i_mode & S_ISVTX) {
- if (current_uid() != path->dentry->d_inode->i_uid)
- return -EPERM;
- }
- if (inode_permission(path->dentry->d_inode, MAY_WRITE))
- return -EPERM;
- return 0;
-#endif
+ /* Could bind mounting the mount namespace inode cause a
+ * mount namespace loop?
+ */
+ struct inode *inode = path->dentry->d_inode;
+ struct proc_ns *ei;
+ struct mnt_namespace *mnt_ns;
+
+ if (!proc_ns_inode(inode))
+ return false;
+
+ ei = get_proc_ns(inode);
+ if (ei->ns_ops != &mntns_operations)
+ return false;
+
+ mnt_ns = ei->ns;
+ return current->nsproxy->mnt_ns->seq >= mnt_ns->seq;
}
struct mount *copy_tree(struct mount *mnt, struct dentry *dentry,
int flag)
{
- struct mount *res, *p, *q;
- struct vfsmount *r;
- struct path path;
+ struct mount *res, *p, *q, *r, *parent;
- if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(&mnt->mnt))
- return NULL;
+ if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt))
+ return ERR_PTR(-EINVAL);
res = q = clone_mnt(mnt, dentry, flag);
- if (!q)
- goto Enomem;
- q->mnt.mnt_mountpoint = mnt->mnt.mnt_mountpoint;
+ if (IS_ERR(q))
+ return q;
+
+ q->mnt_mountpoint = mnt->mnt_mountpoint;
p = mnt;
- list_for_each_entry(r, &mnt->mnt.mnt_mounts, mnt_child) {
+ list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) {
struct mount *s;
if (!is_subdir(r->mnt_mountpoint, dentry))
continue;
- for (s = real_mount(r); s; s = next_mnt(s, r)) {
- if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(&s->mnt)) {
+ for (s = r; s; s = next_mnt(s, r)) {
+ if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(s)) {
s = skip_mnt_tree(s);
continue;
}
- while (p != real_mount(s->mnt.mnt_parent)) {
- p = real_mount(p->mnt.mnt_parent);
- q = real_mount(q->mnt.mnt_parent);
+ while (p != s->mnt_parent) {
+ p = p->mnt_parent;
+ q = q->mnt_parent;
}
p = s;
- path.mnt = &q->mnt;
- path.dentry = p->mnt.mnt_mountpoint;
+ parent = q;
q = clone_mnt(p, p->mnt.mnt_root, flag);
- if (!q)
- goto Enomem;
- br_write_lock(vfsmount_lock);
- list_add_tail(&q->mnt.mnt_list, &res->mnt.mnt_list);
- attach_mnt(q, &path);
- br_write_unlock(vfsmount_lock);
+ if (IS_ERR(q))
+ goto out;
+ br_write_lock(&vfsmount_lock);
+ list_add_tail(&q->mnt_list, &res->mnt_list);
+ attach_mnt(q, parent, p->mnt_mp);
+ br_write_unlock(&vfsmount_lock);
}
}
return res;
-Enomem:
+out:
if (res) {
- LIST_HEAD(umount_list);
- br_write_lock(vfsmount_lock);
- umount_tree(res, 0, &umount_list);
- br_write_unlock(vfsmount_lock);
- release_mounts(&umount_list);
+ br_write_lock(&vfsmount_lock);
+ umount_tree(res, 0);
+ br_write_unlock(&vfsmount_lock);
}
- return NULL;
+ return q;
}
+/* Caller should check returned pointer for errors */
+
struct vfsmount *collect_mounts(struct path *path)
{
struct mount *tree;
- down_write(&namespace_sem);
+ namespace_lock();
tree = copy_tree(real_mount(path->mnt), path->dentry,
CL_COPY_ALL | CL_PRIVATE);
- up_write(&namespace_sem);
- return tree ? &tree->mnt : NULL;
+ namespace_unlock();
+ if (IS_ERR(tree))
+ return ERR_CAST(tree);
+ return &tree->mnt;
}
void drop_collected_mounts(struct vfsmount *mnt)
{
- LIST_HEAD(umount_list);
- down_write(&namespace_sem);
- br_write_lock(vfsmount_lock);
- umount_tree(real_mount(mnt), 0, &umount_list);
- br_write_unlock(vfsmount_lock);
- up_write(&namespace_sem);
- release_mounts(&umount_list);
+ namespace_lock();
+ br_write_lock(&vfsmount_lock);
+ umount_tree(real_mount(mnt), 0);
+ br_write_unlock(&vfsmount_lock);
+ namespace_unlock();
}
int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg,
struct vfsmount *root)
{
- struct vfsmount *mnt;
+ struct mount *mnt;
int res = f(root, arg);
if (res)
return res;
- list_for_each_entry(mnt, &root->mnt_list, mnt_list) {
- res = f(mnt, arg);
+ list_for_each_entry(mnt, &real_mount(root)->mnt_list, mnt_list) {
+ res = f(&mnt->mnt, arg);
if (res)
return res;
}
{
struct mount *p;
- for (p = mnt; p != end; p = next_mnt(p, &mnt->mnt)) {
- if (p->mnt.mnt_group_id && !IS_MNT_SHARED(&p->mnt))
+ for (p = mnt; p != end; p = next_mnt(p, mnt)) {
+ if (p->mnt_group_id && !IS_MNT_SHARED(p))
mnt_release_group_id(p);
}
}
{
struct mount *p;
- for (p = mnt; p; p = recurse ? next_mnt(p, &mnt->mnt) : NULL) {
- if (!p->mnt.mnt_group_id && !IS_MNT_SHARED(&p->mnt)) {
+ for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) {
+ if (!p->mnt_group_id && !IS_MNT_SHARED(p)) {
int err = mnt_alloc_group_id(p);
if (err) {
cleanup_group_ids(mnt, p);
* in allocations.
*/
static int attach_recursive_mnt(struct mount *source_mnt,
- struct path *path, struct path *parent_path)
+ struct mount *dest_mnt,
+ struct mountpoint *dest_mp,
+ struct path *parent_path)
{
LIST_HEAD(tree_list);
- struct vfsmount *dest_mnt = path->mnt;
- struct dentry *dest_dentry = path->dentry;
struct mount *child, *p;
int err;
if (err)
goto out;
}
- err = propagate_mnt(dest_mnt, dest_dentry, &source_mnt->mnt, &tree_list);
+ err = propagate_mnt(dest_mnt, dest_mp, source_mnt, &tree_list);
if (err)
goto out_cleanup_ids;
- br_write_lock(vfsmount_lock);
+ br_write_lock(&vfsmount_lock);
if (IS_MNT_SHARED(dest_mnt)) {
- for (p = source_mnt; p; p = next_mnt(p, &source_mnt->mnt))
+ for (p = source_mnt; p; p = next_mnt(p, source_mnt))
set_mnt_shared(p);
}
if (parent_path) {
detach_mnt(source_mnt, parent_path);
- attach_mnt(source_mnt, path);
- touch_mnt_namespace(parent_path->mnt->mnt_ns);
+ attach_mnt(source_mnt, dest_mnt, dest_mp);
+ touch_mnt_namespace(source_mnt->mnt_ns);
} else {
- mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt);
+ mnt_set_mountpoint(dest_mnt, dest_mp, source_mnt);
commit_tree(source_mnt);
}
list_del_init(&child->mnt_hash);
commit_tree(child);
}
- br_write_unlock(vfsmount_lock);
+ br_write_unlock(&vfsmount_lock);
return 0;
return err;
}
-static int lock_mount(struct path *path)
+static struct mountpoint *lock_mount(struct path *path)
{
struct vfsmount *mnt;
+ struct dentry *dentry = path->dentry;
retry:
- mutex_lock(&path->dentry->d_inode->i_mutex);
- if (unlikely(cant_mount(path->dentry))) {
- mutex_unlock(&path->dentry->d_inode->i_mutex);
- return -ENOENT;
+ mutex_lock(&dentry->d_inode->i_mutex);
+ if (unlikely(cant_mount(dentry))) {
+ mutex_unlock(&dentry->d_inode->i_mutex);
+ return ERR_PTR(-ENOENT);
}
- down_write(&namespace_sem);
+ namespace_lock();
mnt = lookup_mnt(path);
- if (likely(!mnt))
- return 0;
- up_write(&namespace_sem);
+ if (likely(!mnt)) {
+ struct mountpoint *mp = new_mountpoint(dentry);
+ if (IS_ERR(mp)) {
+ namespace_unlock();
+ mutex_unlock(&dentry->d_inode->i_mutex);
+ return mp;
+ }
+ return mp;
+ }
+ namespace_unlock();
mutex_unlock(&path->dentry->d_inode->i_mutex);
path_put(path);
path->mnt = mnt;
- path->dentry = dget(mnt->mnt_root);
+ dentry = path->dentry = dget(mnt->mnt_root);
goto retry;
}
-static void unlock_mount(struct path *path)
+static void unlock_mount(struct mountpoint *where)
{
- up_write(&namespace_sem);
- mutex_unlock(&path->dentry->d_inode->i_mutex);
+ struct dentry *dentry = where->m_dentry;
+ put_mountpoint(where);
+ namespace_unlock();
+ mutex_unlock(&dentry->d_inode->i_mutex);
}
-static int graft_tree(struct vfsmount *mnt, struct path *path)
+static int graft_tree(struct mount *mnt, struct mount *p, struct mountpoint *mp)
{
- if (mnt->mnt_sb->s_flags & MS_NOUSER)
+ if (mnt->mnt.mnt_sb->s_flags & MS_NOUSER)
return -EINVAL;
- if (S_ISDIR(path->dentry->d_inode->i_mode) !=
- S_ISDIR(mnt->mnt_root->d_inode->i_mode))
+ if (S_ISDIR(mp->m_dentry->d_inode->i_mode) !=
+ S_ISDIR(mnt->mnt.mnt_root->d_inode->i_mode))
return -ENOTDIR;
- if (d_unlinked(path->dentry))
- return -ENOENT;
-
- return attach_recursive_mnt(real_mount(mnt), path, NULL);
+ return attach_recursive_mnt(mnt, p, mp, NULL);
}
/*
int type;
int err = 0;
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
-
if (path->dentry != path->mnt->mnt_root)
return -EINVAL;
if (!type)
return -EINVAL;
- down_write(&namespace_sem);
+ namespace_lock();
if (type == MS_SHARED) {
err = invent_group_ids(mnt, recurse);
if (err)
goto out_unlock;
}
- br_write_lock(vfsmount_lock);
- for (m = mnt; m; m = (recurse ? next_mnt(m, &mnt->mnt) : NULL))
+ br_write_lock(&vfsmount_lock);
+ for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL))
change_mnt_propagation(m, type);
- br_write_unlock(vfsmount_lock);
+ br_write_unlock(&vfsmount_lock);
out_unlock:
- up_write(&namespace_sem);
+ namespace_unlock();
return err;
}
/*
* do loopback mount.
*/
-static int do_loopback(struct path *path, char *old_name,
+static int do_loopback(struct path *path, const char *old_name,
int recurse)
{
- LIST_HEAD(umount_list);
struct path old_path;
- struct mount *mnt = NULL, *old;
- int err = mount_is_safe(path);
- if (err)
- return err;
+ struct mount *mnt = NULL, *old, *parent;
+ struct mountpoint *mp;
+ int err;
if (!old_name || !*old_name)
return -EINVAL;
err = kern_path(old_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path);
if (err)
return err;
- err = lock_mount(path);
- if (err)
+ err = -EINVAL;
+ if (mnt_ns_loop(&old_path))
+ goto out;
+
+ mp = lock_mount(path);
+ err = PTR_ERR(mp);
+ if (IS_ERR(mp))
goto out;
old = real_mount(old_path.mnt);
+ parent = real_mount(path->mnt);
err = -EINVAL;
- if (IS_MNT_UNBINDABLE(old_path.mnt))
+ if (IS_MNT_UNBINDABLE(old))
goto out2;
- if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt))
+ if (!check_mnt(parent) || !check_mnt(old))
goto out2;
- err = -ENOMEM;
if (recurse)
mnt = copy_tree(old, old_path.dentry, 0);
else
mnt = clone_mnt(old, old_path.dentry, 0);
- if (!mnt)
+ if (IS_ERR(mnt)) {
+ err = PTR_ERR(mnt);
goto out2;
+ }
- err = graft_tree(&mnt->mnt, path);
+ err = graft_tree(mnt, parent, mp);
if (err) {
- br_write_lock(vfsmount_lock);
- umount_tree(mnt, 0, &umount_list);
- br_write_unlock(vfsmount_lock);
+ br_write_lock(&vfsmount_lock);
+ umount_tree(mnt, 0);
+ br_write_unlock(&vfsmount_lock);
}
out2:
- unlock_mount(path);
- release_mounts(&umount_list);
+ unlock_mount(mp);
out:
path_put(&old_path);
return err;
return 0;
if (readonly_request)
- error = mnt_make_readonly(mnt);
+ error = mnt_make_readonly(real_mount(mnt));
else
- __mnt_unmake_readonly(mnt);
+ __mnt_unmake_readonly(real_mount(mnt));
return error;
}
{
int err;
struct super_block *sb = path->mnt->mnt_sb;
+ struct mount *mnt = real_mount(path->mnt);
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
-
- if (!check_mnt(path->mnt))
+ if (!check_mnt(mnt))
return -EINVAL;
if (path->dentry != path->mnt->mnt_root)
return -EINVAL;
+ /* Don't allow changing of locked mnt flags.
+ *
+ * No locks need to be held here while testing the various
+ * MNT_LOCK flags because those flags can never be cleared
+ * once they are set.
+ */
+ if ((mnt->mnt.mnt_flags & MNT_LOCK_READONLY) &&
+ !(mnt_flags & MNT_READONLY)) {
+ return -EPERM;
+ }
+ if ((mnt->mnt.mnt_flags & MNT_LOCK_NODEV) &&
+ !(mnt_flags & MNT_NODEV)) {
+ /* Was the nodev implicitly added in mount? */
+ if ((mnt->mnt_ns->user_ns != &init_user_ns) &&
+ !(sb->s_type->fs_flags & FS_USERNS_DEV_MOUNT)) {
+ mnt_flags |= MNT_NODEV;
+ } else {
+ return -EPERM;
+ }
+ }
+ if ((mnt->mnt.mnt_flags & MNT_LOCK_NOSUID) &&
+ !(mnt_flags & MNT_NOSUID)) {
+ return -EPERM;
+ }
+ if ((mnt->mnt.mnt_flags & MNT_LOCK_NOEXEC) &&
+ !(mnt_flags & MNT_NOEXEC)) {
+ return -EPERM;
+ }
+ if ((mnt->mnt.mnt_flags & MNT_LOCK_ATIME) &&
+ ((mnt->mnt.mnt_flags & MNT_ATIME_MASK) != (mnt_flags & MNT_ATIME_MASK))) {
+ return -EPERM;
+ }
+
err = security_sb_remount(sb, data);
if (err)
return err;
down_write(&sb->s_umount);
if (flags & MS_BIND)
err = change_mount_flags(path->mnt, flags);
+ else if (!capable(CAP_SYS_ADMIN))
+ err = -EPERM;
else
err = do_remount_sb(sb, flags, data, 0);
if (!err) {
- br_write_lock(vfsmount_lock);
- mnt_flags |= path->mnt->mnt_flags & MNT_PROPAGATION_MASK;
- path->mnt->mnt_flags = mnt_flags;
- br_write_unlock(vfsmount_lock);
+ br_write_lock(&vfsmount_lock);
+ mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK;
+ mnt->mnt.mnt_flags = mnt_flags;
+ br_write_unlock(&vfsmount_lock);
}
up_write(&sb->s_umount);
if (!err) {
- br_write_lock(vfsmount_lock);
- touch_mnt_namespace(path->mnt->mnt_ns);
- br_write_unlock(vfsmount_lock);
+ br_write_lock(&vfsmount_lock);
+ touch_mnt_namespace(mnt->mnt_ns);
+ br_write_unlock(&vfsmount_lock);
}
return err;
}
static inline int tree_contains_unbindable(struct mount *mnt)
{
struct mount *p;
- for (p = mnt; p; p = next_mnt(p, &mnt->mnt)) {
- if (IS_MNT_UNBINDABLE(&p->mnt))
+ for (p = mnt; p; p = next_mnt(p, mnt)) {
+ if (IS_MNT_UNBINDABLE(p))
return 1;
}
return 0;
}
-static int do_move_mount(struct path *path, char *old_name)
+static int do_move_mount(struct path *path, const char *old_name)
{
struct path old_path, parent_path;
- struct vfsmount *p;
+ struct mount *p;
struct mount *old;
- int err = 0;
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
+ struct mountpoint *mp;
+ int err;
if (!old_name || !*old_name)
return -EINVAL;
err = kern_path(old_name, LOOKUP_FOLLOW, &old_path);
if (err)
return err;
- err = lock_mount(path);
- if (err < 0)
+ mp = lock_mount(path);
+ err = PTR_ERR(mp);
+ if (IS_ERR(mp))
goto out;
- err = -EINVAL;
- if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt))
- goto out1;
+ old = real_mount(old_path.mnt);
+ p = real_mount(path->mnt);
- if (d_unlinked(path->dentry))
+ err = -EINVAL;
+ if (!check_mnt(p) || !check_mnt(old))
goto out1;
err = -EINVAL;
if (old_path.dentry != old_path.mnt->mnt_root)
goto out1;
- old = real_mount(old_path.mnt);
-
- if (!mnt_has_parent(old_path.mnt))
+ if (!mnt_has_parent(old))
goto out1;
if (S_ISDIR(path->dentry->d_inode->i_mode) !=
/*
* Don't move a mount residing in a shared parent.
*/
- if (IS_MNT_SHARED(old_path.mnt->mnt_parent))
+ if (IS_MNT_SHARED(old->mnt_parent))
goto out1;
/*
* Don't move a mount tree containing unbindable mounts to a destination
* mount which is shared.
*/
- if (IS_MNT_SHARED(path->mnt) &&
- tree_contains_unbindable(old))
+ if (IS_MNT_SHARED(p) && tree_contains_unbindable(old))
goto out1;
err = -ELOOP;
- for (p = path->mnt; mnt_has_parent(p); p = p->mnt_parent)
- if (p == old_path.mnt)
+ for (; mnt_has_parent(p); p = p->mnt_parent)
+ if (p == old)
goto out1;
- err = attach_recursive_mnt(old, path, &parent_path);
+ err = attach_recursive_mnt(old, real_mount(path->mnt), mp, &parent_path);
if (err)
goto out1;
/* if the mount is moved, it should no longer be expire
* automatically */
- list_del_init(&old_path.mnt->mnt_expire);
+ list_del_init(&old->mnt_expire);
out1:
- unlock_mount(path);
+ unlock_mount(mp);
out:
if (!err)
path_put(&parent_path);
return ERR_PTR(err);
}
-static struct vfsmount *
-do_kern_mount(const char *fstype, int flags, const char *name, void *data)
-{
- struct file_system_type *type = get_fs_type(fstype);
- struct vfsmount *mnt;
- if (!type)
- return ERR_PTR(-ENODEV);
- mnt = vfs_kern_mount(type, flags, name, data);
- if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) &&
- !mnt->mnt_sb->s_subtype)
- mnt = fs_set_subtype(mnt, fstype);
- put_filesystem(type);
- return mnt;
-}
-
/*
* add a mount into a namespace's mount tree
*/
-static int do_add_mount(struct vfsmount *newmnt, struct path *path, int mnt_flags)
+static int do_add_mount(struct mount *newmnt, struct path *path, int mnt_flags)
{
+ struct mountpoint *mp;
+ struct mount *parent;
int err;
mnt_flags &= ~(MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL);
- err = lock_mount(path);
- if (err)
- return err;
+ mp = lock_mount(path);
+ if (IS_ERR(mp))
+ return PTR_ERR(mp);
+ parent = real_mount(path->mnt);
err = -EINVAL;
- if (!(mnt_flags & MNT_SHRINKABLE) && !check_mnt(path->mnt))
- goto unlock;
+ if (unlikely(!check_mnt(parent))) {
+ /* that's acceptable only for automounts done in private ns */
+ if (!(mnt_flags & MNT_SHRINKABLE))
+ goto unlock;
+ /* ... and for those we'd better have mountpoint still alive */
+ if (!parent->mnt_ns)
+ goto unlock;
+ }
/* Refuse the same filesystem on the same mount point */
err = -EBUSY;
- if (path->mnt->mnt_sb == newmnt->mnt_sb &&
+ if (path->mnt->mnt_sb == newmnt->mnt.mnt_sb &&
path->mnt->mnt_root == path->dentry)
goto unlock;
err = -EINVAL;
- if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode))
+ if (S_ISLNK(newmnt->mnt.mnt_root->d_inode->i_mode))
goto unlock;
- newmnt->mnt_flags = mnt_flags;
- err = graft_tree(newmnt, path);
+ newmnt->mnt.mnt_flags = mnt_flags;
+ err = graft_tree(newmnt, parent, mp);
unlock:
- unlock_mount(path);
+ unlock_mount(mp);
return err;
}
* create a new mount for userspace and request it to be added into the
* namespace's tree
*/
-static int do_new_mount(struct path *path, char *type, int flags,
- int mnt_flags, char *name, void *data)
+static int do_new_mount(struct path *path, const char *fstype, int flags,
+ int mnt_flags, const char *name, void *data)
{
+ struct file_system_type *type;
+ struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns;
struct vfsmount *mnt;
int err;
- if (!type)
+ if (!fstype)
return -EINVAL;
- /* we need capabilities... */
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
+ type = get_fs_type(fstype);
+ if (!type)
+ return -ENODEV;
- mnt = do_kern_mount(type, flags, name, data);
+ if (user_ns != &init_user_ns) {
+ if (!(type->fs_flags & FS_USERNS_MOUNT)) {
+ put_filesystem(type);
+ return -EPERM;
+ }
+ /* Only in special cases allow devices from mounts
+ * created outside the initial user namespace.
+ */
+ if (!(type->fs_flags & FS_USERNS_DEV_MOUNT)) {
+ flags |= MS_NODEV;
+ mnt_flags |= MNT_NODEV | MNT_LOCK_NODEV;
+ }
+ }
+
+ mnt = vfs_kern_mount(type, flags, name, data);
+ if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) &&
+ !mnt->mnt_sb->s_subtype)
+ mnt = fs_set_subtype(mnt, fstype);
+
+ put_filesystem(type);
if (IS_ERR(mnt))
return PTR_ERR(mnt);
- err = do_add_mount(mnt, path, mnt_flags);
+ err = do_add_mount(real_mount(mnt), path, mnt_flags);
if (err)
mntput(mnt);
return err;
int finish_automount(struct vfsmount *m, struct path *path)
{
+ struct mount *mnt = real_mount(m);
int err;
/* The new mount record should have at least 2 refs to prevent it being
* expired before we get a chance to add it
*/
- BUG_ON(mnt_get_count(m) < 2);
+ BUG_ON(mnt_get_count(mnt) < 2);
if (m->mnt_sb == path->mnt->mnt_sb &&
m->mnt_root == path->dentry) {
goto fail;
}
- err = do_add_mount(m, path, path->mnt->mnt_flags | MNT_SHRINKABLE);
+ err = do_add_mount(mnt, path, path->mnt->mnt_flags | MNT_SHRINKABLE);
if (!err)
return 0;
fail:
/* remove m from any expiration list it may be on */
- if (!list_empty(&m->mnt_expire)) {
- down_write(&namespace_sem);
- br_write_lock(vfsmount_lock);
- list_del_init(&m->mnt_expire);
- br_write_unlock(vfsmount_lock);
- up_write(&namespace_sem);
+ if (!list_empty(&mnt->mnt_expire)) {
+ namespace_lock();
+ br_write_lock(&vfsmount_lock);
+ list_del_init(&mnt->mnt_expire);
+ br_write_unlock(&vfsmount_lock);
+ namespace_unlock();
}
mntput(m);
mntput(m);
*/
void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list)
{
- down_write(&namespace_sem);
- br_write_lock(vfsmount_lock);
+ namespace_lock();
+ br_write_lock(&vfsmount_lock);
- list_add_tail(&mnt->mnt_expire, expiry_list);
+ list_add_tail(&real_mount(mnt)->mnt_expire, expiry_list);
- br_write_unlock(vfsmount_lock);
- up_write(&namespace_sem);
+ br_write_unlock(&vfsmount_lock);
+ namespace_unlock();
}
EXPORT_SYMBOL(mnt_set_expiry);
{
struct mount *mnt, *next;
LIST_HEAD(graveyard);
- LIST_HEAD(umounts);
if (list_empty(mounts))
return;
- down_write(&namespace_sem);
- br_write_lock(vfsmount_lock);
+ namespace_lock();
+ br_write_lock(&vfsmount_lock);
/* extract from the expiration list every vfsmount that matches the
* following criteria:
* - still marked for expiry (marked on the last call here; marks are
* cleared by mntput())
*/
- list_for_each_entry_safe(mnt, next, mounts, mnt.mnt_expire) {
- if (!xchg(&mnt->mnt.mnt_expiry_mark, 1) ||
- propagate_mount_busy(&mnt->mnt, 1))
+ list_for_each_entry_safe(mnt, next, mounts, mnt_expire) {
+ if (!xchg(&mnt->mnt_expiry_mark, 1) ||
+ propagate_mount_busy(mnt, 1))
continue;
- list_move(&mnt->mnt.mnt_expire, &graveyard);
+ list_move(&mnt->mnt_expire, &graveyard);
}
while (!list_empty(&graveyard)) {
- mnt = list_first_entry(&graveyard, struct mount, mnt.mnt_expire);
- touch_mnt_namespace(mnt->mnt.mnt_ns);
- umount_tree(mnt, 1, &umounts);
+ mnt = list_first_entry(&graveyard, struct mount, mnt_expire);
+ touch_mnt_namespace(mnt->mnt_ns);
+ umount_tree(mnt, 1);
}
- br_write_unlock(vfsmount_lock);
- up_write(&namespace_sem);
-
- release_mounts(&umounts);
+ br_write_unlock(&vfsmount_lock);
+ namespace_unlock();
}
EXPORT_SYMBOL_GPL(mark_mounts_for_expiry);
int found = 0;
repeat:
- next = this_parent->mnt.mnt_mounts.next;
+ next = this_parent->mnt_mounts.next;
resume:
- while (next != &this_parent->mnt.mnt_mounts) {
+ while (next != &this_parent->mnt_mounts) {
struct list_head *tmp = next;
- struct mount *mnt = list_entry(tmp, struct mount, mnt.mnt_child);
+ struct mount *mnt = list_entry(tmp, struct mount, mnt_child);
next = tmp->next;
if (!(mnt->mnt.mnt_flags & MNT_SHRINKABLE))
/*
* Descend a level if the d_mounts list is non-empty.
*/
- if (!list_empty(&mnt->mnt.mnt_mounts)) {
+ if (!list_empty(&mnt->mnt_mounts)) {
this_parent = mnt;
goto repeat;
}
- if (!propagate_mount_busy(&mnt->mnt, 1)) {
- list_move_tail(&mnt->mnt.mnt_expire, graveyard);
+ if (!propagate_mount_busy(mnt, 1)) {
+ list_move_tail(&mnt->mnt_expire, graveyard);
found++;
}
}
* All done at this level ... ascend and resume the search
*/
if (this_parent != parent) {
- next = this_parent->mnt.mnt_child.next;
- this_parent = real_mount(this_parent->mnt.mnt_parent);
+ next = this_parent->mnt_child.next;
+ this_parent = this_parent->mnt_parent;
goto resume;
}
return found;
*
* vfsmount_lock must be held for write
*/
-static void shrink_submounts(struct mount *mnt, struct list_head *umounts)
+static void shrink_submounts(struct mount *mnt)
{
LIST_HEAD(graveyard);
struct mount *m;
while (select_submounts(mnt, &graveyard)) {
while (!list_empty(&graveyard)) {
m = list_first_entry(&graveyard, struct mount,
- mnt.mnt_expire);
- touch_mnt_namespace(m->mnt.mnt_ns);
- umount_tree(m, 1, umounts);
+ mnt_expire);
+ touch_mnt_namespace(m->mnt_ns);
+ umount_tree(m, 1);
}
}
}
* Therefore, if this magic number is present, it carries no information
* and must be discarded.
*/
-long do_mount(char *dev_name, char *dir_name, char *type_page,
- unsigned long flags, void *data_page)
+long do_mount(const char *dev_name, const char *dir_name,
+ const char *type_page, unsigned long flags, void *data_page)
{
struct path path;
int retval = 0;
retval = security_sb_mount(dev_name, &path,
type_page, flags, data_page);
+ if (!retval && !may_mount())
+ retval = -EPERM;
if (retval)
goto dput_out;
if (flags & MS_RDONLY)
mnt_flags |= MNT_READONLY;
+ /* The default atime for remount is preservation */
+ if ((flags & MS_REMOUNT) &&
+ ((flags & (MS_NOATIME | MS_NODIRATIME | MS_RELATIME |
+ MS_STRICTATIME)) == 0)) {
+ mnt_flags &= ~MNT_ATIME_MASK;
+ mnt_flags |= path.mnt->mnt_flags & MNT_ATIME_MASK;
+ }
+
flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | MS_BORN |
MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT |
MS_STRICTATIME);
return retval;
}
-static struct mnt_namespace *alloc_mnt_ns(void)
+static void free_mnt_ns(struct mnt_namespace *ns)
+{
+ proc_free_inum(ns->proc_inum);
+ put_user_ns(ns->user_ns);
+ kfree(ns);
+}
+
+/*
+ * Assign a sequence number so we can detect when we attempt to bind
+ * mount a reference to an older mount namespace into the current
+ * mount namespace, preventing reference counting loops. A 64bit
+ * number incrementing at 10Ghz will take 12,427 years to wrap which
+ * is effectively never, so we can ignore the possibility.
+ */
+static atomic64_t mnt_ns_seq = ATOMIC64_INIT(1);
+
+static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns)
{
struct mnt_namespace *new_ns;
+ int ret;
new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL);
if (!new_ns)
return ERR_PTR(-ENOMEM);
+ ret = proc_alloc_inum(&new_ns->proc_inum);
+ if (ret) {
+ kfree(new_ns);
+ return ERR_PTR(ret);
+ }
+ new_ns->seq = atomic64_add_return(1, &mnt_ns_seq);
atomic_set(&new_ns->count, 1);
new_ns->root = NULL;
INIT_LIST_HEAD(&new_ns->list);
init_waitqueue_head(&new_ns->poll);
new_ns->event = 0;
+ new_ns->user_ns = get_user_ns(user_ns);
return new_ns;
}
-void mnt_make_longterm(struct vfsmount *mnt)
-{
- __mnt_make_longterm(mnt);
-}
-
-void mnt_make_shortterm(struct vfsmount *mnt)
-{
-#ifdef CONFIG_SMP
- if (atomic_add_unless(&mnt->mnt_longterm, -1, 1))
- return;
- br_write_lock(vfsmount_lock);
- atomic_dec(&mnt->mnt_longterm);
- br_write_unlock(vfsmount_lock);
-#endif
-}
-
/*
* Allocate a new namespace structure and populate it with contents
* copied from the namespace of the passed in task structure.
*/
static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
- struct fs_struct *fs)
+ struct user_namespace *user_ns, struct fs_struct *fs)
{
struct mnt_namespace *new_ns;
struct vfsmount *rootmnt = NULL, *pwdmnt = NULL;
struct mount *p, *q;
+ struct mount *old = mnt_ns->root;
struct mount *new;
+ int copy_flags;
- new_ns = alloc_mnt_ns();
+ new_ns = alloc_mnt_ns(user_ns);
if (IS_ERR(new_ns))
return new_ns;
- down_write(&namespace_sem);
+ namespace_lock();
/* First pass: copy the tree topology */
- new = copy_tree(real_mount(mnt_ns->root), mnt_ns->root->mnt_root,
- CL_COPY_ALL | CL_EXPIRE);
- if (!new) {
- up_write(&namespace_sem);
- kfree(new_ns);
- return ERR_PTR(-ENOMEM);
- }
- new_ns->root = &new->mnt;
- br_write_lock(vfsmount_lock);
- list_add_tail(&new_ns->list, &new_ns->root->mnt_list);
- br_write_unlock(vfsmount_lock);
+ copy_flags = CL_COPY_ALL | CL_EXPIRE;
+ if (user_ns != mnt_ns->user_ns)
+ copy_flags |= CL_SHARED_TO_SLAVE | CL_UNPRIVILEGED;
+ new = copy_tree(old, old->mnt.mnt_root, copy_flags);
+ if (IS_ERR(new)) {
+ namespace_unlock();
+ free_mnt_ns(new_ns);
+ return ERR_CAST(new);
+ }
+ new_ns->root = new;
+ br_write_lock(&vfsmount_lock);
+ list_add_tail(&new_ns->list, &new->mnt_list);
+ br_write_unlock(&vfsmount_lock);
/*
* Second pass: switch the tsk->fs->* elements and mark new vfsmounts
* as belonging to new namespace. We have already acquired a private
* fs_struct, so tsk->fs->lock is not needed.
*/
- p = real_mount(mnt_ns->root);
+ p = old;
q = new;
while (p) {
- q->mnt.mnt_ns = new_ns;
- __mnt_make_longterm(&q->mnt);
+ q->mnt_ns = new_ns;
if (fs) {
if (&p->mnt == fs->root.mnt) {
fs->root.mnt = mntget(&q->mnt);
- __mnt_make_longterm(&q->mnt);
- mnt_make_shortterm(&p->mnt);
rootmnt = &p->mnt;
}
if (&p->mnt == fs->pwd.mnt) {
fs->pwd.mnt = mntget(&q->mnt);
- __mnt_make_longterm(&q->mnt);
- mnt_make_shortterm(&p->mnt);
pwdmnt = &p->mnt;
}
}
- p = next_mnt(p, mnt_ns->root);
- q = next_mnt(q, new_ns->root);
+ p = next_mnt(p, old);
+ q = next_mnt(q, new);
}
- up_write(&namespace_sem);
+ namespace_unlock();
if (rootmnt)
mntput(rootmnt);
}
struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,
- struct fs_struct *new_fs)
+ struct user_namespace *user_ns, struct fs_struct *new_fs)
{
struct mnt_namespace *new_ns;
if (!(flags & CLONE_NEWNS))
return ns;
- new_ns = dup_mnt_ns(ns, new_fs);
+ new_ns = dup_mnt_ns(ns, user_ns, new_fs);
put_mnt_ns(ns);
return new_ns;
* create_mnt_ns - creates a private namespace and adds a root filesystem
* @mnt: pointer to the new root filesystem mountpoint
*/
-static struct mnt_namespace *create_mnt_ns(struct vfsmount *mnt)
+static struct mnt_namespace *create_mnt_ns(struct vfsmount *m)
{
- struct mnt_namespace *new_ns;
-
- new_ns = alloc_mnt_ns();
+ struct mnt_namespace *new_ns = alloc_mnt_ns(&init_user_ns);
if (!IS_ERR(new_ns)) {
+ struct mount *mnt = real_mount(m);
mnt->mnt_ns = new_ns;
- __mnt_make_longterm(mnt);
new_ns->root = mnt;
- list_add(&new_ns->list, &new_ns->root->mnt_list);
+ list_add(&mnt->mnt_list, &new_ns->list);
} else {
- mntput(mnt);
+ mntput(m);
}
return new_ns;
}
{
int ret;
char *kernel_type;
- char *kernel_dir;
+ struct filename *kernel_dir;
char *kernel_dev;
unsigned long data_page;
if (ret < 0)
goto out_data;
- ret = do_mount(kernel_dev, kernel_dir, kernel_type, flags,
+ ret = do_mount(kernel_dev, kernel_dir->name, kernel_type, flags,
(void *) data_page);
free_page(data_page);
*
* namespace_sem or vfsmount_lock is held
*/
-bool is_path_reachable(struct vfsmount *mnt, struct dentry *dentry,
+bool is_path_reachable(struct mount *mnt, struct dentry *dentry,
const struct path *root)
{
- while (mnt != root->mnt && mnt_has_parent(mnt)) {
+ while (&mnt->mnt != root->mnt && mnt_has_parent(mnt)) {
dentry = mnt->mnt_mountpoint;
mnt = mnt->mnt_parent;
}
- return mnt == root->mnt && is_subdir(dentry, root->dentry);
+ return &mnt->mnt == root->mnt && is_subdir(dentry, root->dentry);
}
int path_is_under(struct path *path1, struct path *path2)
{
int res;
- br_read_lock(vfsmount_lock);
- res = is_path_reachable(path1->mnt, path1->dentry, path2);
- br_read_unlock(vfsmount_lock);
+ br_read_lock(&vfsmount_lock);
+ res = is_path_reachable(real_mount(path1->mnt), path1->dentry, path2);
+ br_read_unlock(&vfsmount_lock);
return res;
}
EXPORT_SYMBOL(path_is_under);
const char __user *, put_old)
{
struct path new, old, parent_path, root_parent, root;
- struct mount *new_mnt, *root_mnt;
+ struct mount *new_mnt, *root_mnt, *old_mnt;
+ struct mountpoint *old_mp, *root_mp;
int error;
- if (!capable(CAP_SYS_ADMIN))
+ if (!may_mount())
return -EPERM;
error = user_path_dir(new_root, &new);
goto out2;
get_fs_root(current->fs, &root);
- error = lock_mount(&old);
- if (error)
+ old_mp = lock_mount(&old);
+ error = PTR_ERR(old_mp);
+ if (IS_ERR(old_mp))
goto out3;
error = -EINVAL;
new_mnt = real_mount(new.mnt);
root_mnt = real_mount(root.mnt);
- if (IS_MNT_SHARED(old.mnt) ||
- IS_MNT_SHARED(new.mnt->mnt_parent) ||
- IS_MNT_SHARED(root.mnt->mnt_parent))
+ old_mnt = real_mount(old.mnt);
+ if (IS_MNT_SHARED(old_mnt) ||
+ IS_MNT_SHARED(new_mnt->mnt_parent) ||
+ IS_MNT_SHARED(root_mnt->mnt_parent))
goto out4;
- if (!check_mnt(root.mnt) || !check_mnt(new.mnt))
+ if (!check_mnt(root_mnt) || !check_mnt(new_mnt))
goto out4;
error = -ENOENT;
if (d_unlinked(new.dentry))
goto out4;
- if (d_unlinked(old.dentry))
- goto out4;
error = -EBUSY;
- if (new.mnt == root.mnt ||
- old.mnt == root.mnt)
+ if (new_mnt == root_mnt || old_mnt == root_mnt)
goto out4; /* loop, on the same file system */
error = -EINVAL;
if (root.mnt->mnt_root != root.dentry)
goto out4; /* not a mountpoint */
- if (!mnt_has_parent(root.mnt))
+ if (!mnt_has_parent(root_mnt))
goto out4; /* not attached */
+ root_mp = root_mnt->mnt_mp;
if (new.mnt->mnt_root != new.dentry)
goto out4; /* not a mountpoint */
- if (!mnt_has_parent(new.mnt))
+ if (!mnt_has_parent(new_mnt))
goto out4; /* not attached */
/* make sure we can reach put_old from new_root */
- if (!is_path_reachable(old.mnt, old.dentry, &new))
+ if (!is_path_reachable(old_mnt, old.dentry, &new))
+ goto out4;
+ /* make certain new is below the root */
+ if (!is_path_reachable(new_mnt, new.dentry, &root))
goto out4;
- br_write_lock(vfsmount_lock);
+ root_mp->m_count++; /* pin it so it won't go away */
+ br_write_lock(&vfsmount_lock);
detach_mnt(new_mnt, &parent_path);
detach_mnt(root_mnt, &root_parent);
/* mount old root on put_old */
- attach_mnt(root_mnt, &old);
+ attach_mnt(root_mnt, old_mnt, old_mp);
/* mount new_root on / */
- attach_mnt(new_mnt, &root_parent);
+ attach_mnt(new_mnt, real_mount(root_parent.mnt), root_mp);
touch_mnt_namespace(current->nsproxy->mnt_ns);
- br_write_unlock(vfsmount_lock);
+ br_write_unlock(&vfsmount_lock);
chroot_fs_refs(&root, &new);
+ put_mountpoint(root_mp);
error = 0;
out4:
- unlock_mount(&old);
+ unlock_mount(old_mp);
if (!error) {
path_put(&root_parent);
path_put(&parent_path);
struct vfsmount *mnt;
struct mnt_namespace *ns;
struct path root;
+ struct file_system_type *type;
- mnt = do_kern_mount("rootfs", 0, "rootfs", NULL);
+ type = get_fs_type("rootfs");
+ if (!type)
+ panic("Can't find rootfs type");
+ mnt = vfs_kern_mount(type, 0, "rootfs", NULL);
+ put_filesystem(type);
if (IS_ERR(mnt))
panic("Can't create rootfs");
init_task.nsproxy->mnt_ns = ns;
get_mnt_ns(ns);
- root.mnt = ns->root;
- root.dentry = ns->root->mnt_root;
+ root.mnt = mnt;
+ root.dentry = mnt->mnt_root;
set_fs_pwd(current->fs, &root);
set_fs_root(current->fs, &root);
0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC);
+ mountpoint_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC);
- if (!mount_hashtable)
+ if (!mount_hashtable || !mountpoint_hashtable)
panic("Failed to allocate mount hash table\n");
printk(KERN_INFO "Mount-cache hash table entries: %lu\n", HASH_SIZE);
for (u = 0; u < HASH_SIZE; u++)
INIT_LIST_HEAD(&mount_hashtable[u]);
+ for (u = 0; u < HASH_SIZE; u++)
+ INIT_LIST_HEAD(&mountpoint_hashtable[u]);
- br_lock_init(vfsmount_lock);
+ br_lock_init(&vfsmount_lock);
err = sysfs_init();
if (err)
void put_mnt_ns(struct mnt_namespace *ns)
{
- LIST_HEAD(umount_list);
-
if (!atomic_dec_and_test(&ns->count))
return;
- down_write(&namespace_sem);
- br_write_lock(vfsmount_lock);
- umount_tree(real_mount(ns->root), 0, &umount_list);
- br_write_unlock(vfsmount_lock);
- up_write(&namespace_sem);
- release_mounts(&umount_list);
- kfree(ns);
+ namespace_lock();
+ br_write_lock(&vfsmount_lock);
+ umount_tree(ns->root, 0);
+ br_write_unlock(&vfsmount_lock);
+ namespace_unlock();
+ free_mnt_ns(ns);
}
struct vfsmount *kern_mount_data(struct file_system_type *type, void *data)
* it is a longterm mount, don't release mnt until
* we unmount before file sys is unregistered
*/
- mnt_make_longterm(mnt);
+ real_mount(mnt)->mnt_ns = MNT_NS_INTERNAL;
}
return mnt;
}
{
/* release long term mount so mount point can be released */
if (!IS_ERR_OR_NULL(mnt)) {
- mnt_make_shortterm(mnt);
+ br_write_lock(&vfsmount_lock);
+ real_mount(mnt)->mnt_ns = NULL;
+ br_write_unlock(&vfsmount_lock);
mntput(mnt);
}
}
bool our_mnt(struct vfsmount *mnt)
{
- return check_mnt(mnt);
+ return check_mnt(real_mount(mnt));
}
+
+bool current_chrooted(void)
+{
+ /* Does the current process have a non-standard root */
+ struct path ns_root;
+ struct path fs_root;
+ bool chrooted;
+
+ /* Find the namespace root */
+ ns_root.mnt = ¤t->nsproxy->mnt_ns->root->mnt;
+ ns_root.dentry = ns_root.mnt->mnt_root;
+ path_get(&ns_root);
+ while (d_mountpoint(ns_root.dentry) && follow_down_one(&ns_root))
+ ;
+
+ get_fs_root(current->fs, &fs_root);
+
+ chrooted = !path_equal(&fs_root, &ns_root);
+
+ path_put(&fs_root);
+ path_put(&ns_root);
+
+ return chrooted;
+}
+
+void update_mnt_policy(struct user_namespace *userns)
+{
+ struct mnt_namespace *ns = current->nsproxy->mnt_ns;
+ struct mount *mnt;
+
+ down_read(&namespace_sem);
+ list_for_each_entry(mnt, &ns->list, mnt_list) {
+ switch (mnt->mnt.mnt_sb->s_magic) {
+ case SYSFS_MAGIC:
+ userns->may_mount_sysfs = true;
+ break;
+ case PROC_SUPER_MAGIC:
+ userns->may_mount_proc = true;
+ break;
+ }
+ if (userns->may_mount_sysfs && userns->may_mount_proc)
+ break;
+ }
+ up_read(&namespace_sem);
+}
+
+static void *mntns_get(struct task_struct *task)
+{
+ struct mnt_namespace *ns = NULL;
+ struct nsproxy *nsproxy;
+
+ rcu_read_lock();
+ nsproxy = task_nsproxy(task);
+ if (nsproxy) {
+ ns = nsproxy->mnt_ns;
+ get_mnt_ns(ns);
+ }
+ rcu_read_unlock();
+
+ return ns;
+}
+
+static void mntns_put(void *ns)
+{
+ put_mnt_ns(ns);
+}
+
+static int mntns_install(struct nsproxy *nsproxy, void *ns)
+{
+ struct fs_struct *fs = current->fs;
+ struct mnt_namespace *mnt_ns = ns;
+ struct path root;
+
+ if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) ||
+ !nsown_capable(CAP_SYS_CHROOT) ||
+ !nsown_capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ if (fs->users != 1)
+ return -EINVAL;
+
+ get_mnt_ns(mnt_ns);
+ put_mnt_ns(nsproxy->mnt_ns);
+ nsproxy->mnt_ns = mnt_ns;
+
+ /* Find the root */
+ root.mnt = &mnt_ns->root->mnt;
+ root.dentry = mnt_ns->root->mnt.mnt_root;
+ path_get(&root);
+ while(d_mountpoint(root.dentry) && follow_down_one(&root))
+ ;
+
+ /* Update the pwd and root */
+ set_fs_pwd(fs, &root);
+ set_fs_root(fs, &root);
+
+ path_put(&root);
+ return 0;
+}
+
+static unsigned int mntns_inum(void *ns)
+{
+ struct mnt_namespace *mnt_ns = ns;
+ return mnt_ns->proc_inum;
+}
+
+const struct proc_ns_operations mntns_operations = {
+ .name = "mnt",
+ .type = CLONE_NEWNS,
+ .get = mntns_get,
+ .put = mntns_put,
+ .install = mntns_install,
+ .inum = mntns_inum,
+};
projects / linux-3.10.git / blobdiff