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-rw-r--r--Documentation/filesystems/path-lookup.rst7
-rw-r--r--fs/autofs/dev-ioctl.c6
-rw-r--r--fs/internal.h1
-rw-r--r--fs/namei.c1474
-rw-r--r--fs/namespace.c96
-rw-r--r--fs/open.c4
-rw-r--r--include/linux/namei.h4
7 files changed, 680 insertions, 912 deletions
diff --git a/Documentation/filesystems/path-lookup.rst b/Documentation/filesystems/path-lookup.rst
index a3216979298b..f46b05e9b96c 100644
--- a/Documentation/filesystems/path-lookup.rst
+++ b/Documentation/filesystems/path-lookup.rst
@@ -404,11 +404,8 @@ that is the "next" component in the pathname.
``int last_type``
~~~~~~~~~~~~~~~~~
-This is one of ``LAST_NORM``, ``LAST_ROOT``, ``LAST_DOT``, ``LAST_DOTDOT``, or
-``LAST_BIND``. The ``last`` field is only valid if the type is
-``LAST_NORM``. ``LAST_BIND`` is used when following a symlink and no
-components of the symlink have been processed yet. Others should be
-fairly self-explanatory.
+This is one of ``LAST_NORM``, ``LAST_ROOT``, ``LAST_DOT`` or ``LAST_DOTDOT``.
+The ``last`` field is only valid if the type is ``LAST_NORM``.
``struct path root``
~~~~~~~~~~~~~~~~~~~~
diff --git a/fs/autofs/dev-ioctl.c b/fs/autofs/dev-ioctl.c
index a3cdb0036c5d..f3a0f412b43b 100644
--- a/fs/autofs/dev-ioctl.c
+++ b/fs/autofs/dev-ioctl.c
@@ -186,7 +186,7 @@ static int find_autofs_mount(const char *pathname,
struct path path;
int err;
- err = kern_path_mountpoint(AT_FDCWD, pathname, &path, 0);
+ err = kern_path(pathname, LOOKUP_MOUNTPOINT, &path);
if (err)
return err;
err = -ENOENT;
@@ -519,8 +519,8 @@ static int autofs_dev_ioctl_ismountpoint(struct file *fp,
if (!fp || param->ioctlfd == -1) {
if (autofs_type_any(type))
- err = kern_path_mountpoint(AT_FDCWD,
- name, &path, LOOKUP_FOLLOW);
+ err = kern_path(name, LOOKUP_FOLLOW | LOOKUP_MOUNTPOINT,
+ &path);
else
err = find_autofs_mount(name, &path,
test_by_type, &type);
diff --git a/fs/internal.h b/fs/internal.h
index 4d37912a5587..aa5d45524e87 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -60,7 +60,6 @@ extern int finish_clean_context(struct fs_context *fc);
*/
extern int filename_lookup(int dfd, struct filename *name, unsigned flags,
struct path *path, struct path *root);
-extern int user_path_mountpoint_at(int, const char __user *, unsigned int, struct path *);
extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
const char *, unsigned int, struct path *);
long do_mknodat(int dfd, const char __user *filename, umode_t mode,
diff --git a/fs/namei.c b/fs/namei.c
index db6565c99825..61fdb77a7d58 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -503,9 +503,10 @@ struct nameidata {
} *stack, internal[EMBEDDED_LEVELS];
struct filename *name;
struct nameidata *saved;
- struct inode *link_inode;
unsigned root_seq;
int dfd;
+ kuid_t dir_uid;
+ umode_t dir_mode;
} __randomize_layout;
static void set_nameidata(struct nameidata *p, int dfd, struct filename *name)
@@ -530,52 +531,34 @@ static void restore_nameidata(void)
kfree(now->stack);
}
-static int __nd_alloc_stack(struct nameidata *nd)
+static bool nd_alloc_stack(struct nameidata *nd)
{
struct saved *p;
- if (nd->flags & LOOKUP_RCU) {
- p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved),
- GFP_ATOMIC);
- if (unlikely(!p))
- return -ECHILD;
- } else {
- p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved),
- GFP_KERNEL);
- if (unlikely(!p))
- return -ENOMEM;
- }
+ p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved),
+ nd->flags & LOOKUP_RCU ? GFP_ATOMIC : GFP_KERNEL);
+ if (unlikely(!p))
+ return false;
memcpy(p, nd->internal, sizeof(nd->internal));
nd->stack = p;
- return 0;
+ return true;
}
/**
- * 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);
-}
-
-static inline int nd_alloc_stack(struct nameidata *nd)
-{
- if (likely(nd->depth != EMBEDDED_LEVELS))
- return 0;
- if (likely(nd->stack != nd->internal))
- return 0;
- return __nd_alloc_stack(nd);
+ return is_subdir(dentry, mnt->mnt_root);
}
static void drop_links(struct nameidata *nd)
@@ -608,10 +591,9 @@ static void terminate_walk(struct nameidata *nd)
}
/* path_put is needed afterwards regardless of success or failure */
-static bool legitimize_path(struct nameidata *nd,
- struct path *path, unsigned seq)
+static bool __legitimize_path(struct path *path, unsigned seq, unsigned mseq)
{
- int res = __legitimize_mnt(path->mnt, nd->m_seq);
+ int res = __legitimize_mnt(path->mnt, mseq);
if (unlikely(res)) {
if (res > 0)
path->mnt = NULL;
@@ -625,6 +607,12 @@ static bool legitimize_path(struct nameidata *nd,
return !read_seqcount_retry(&path->dentry->d_seq, seq);
}
+static inline bool legitimize_path(struct nameidata *nd,
+ struct path *path, unsigned seq)
+{
+ return __legitimize_path(path, nd->m_seq, seq);
+}
+
static bool legitimize_links(struct nameidata *nd)
{
int i;
@@ -858,25 +846,6 @@ static int set_root(struct nameidata *nd)
return 0;
}
-static void path_put_conditional(struct path *path, struct nameidata *nd)
-{
- dput(path->dentry);
- if (path->mnt != nd->path.mnt)
- mntput(path->mnt);
-}
-
-static inline void path_to_nameidata(const struct path *path,
- struct nameidata *nd)
-{
- if (!(nd->flags & LOOKUP_RCU)) {
- dput(nd->path.dentry);
- if (nd->path.mnt != path->mnt)
- mntput(nd->path.mnt);
- }
- nd->path.mnt = path->mnt;
- nd->path.dentry = path->dentry;
-}
-
static int nd_jump_root(struct nameidata *nd)
{
if (unlikely(nd->flags & LOOKUP_BENEATH))
@@ -969,28 +938,21 @@ int sysctl_protected_regular __read_mostly;
*
* Returns 0 if following the symlink is allowed, -ve on error.
*/
-static inline int may_follow_link(struct nameidata *nd)
+static inline int may_follow_link(struct nameidata *nd, const struct inode *inode)
{
- const struct inode *inode;
- const struct inode *parent;
- kuid_t puid;
-
if (!sysctl_protected_symlinks)
return 0;
/* Allowed if owner and follower match. */
- inode = nd->link_inode;
if (uid_eq(current_cred()->fsuid, inode->i_uid))
return 0;
/* Allowed if parent directory not sticky and world-writable. */
- parent = nd->inode;
- if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH))
+ if ((nd->dir_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH))
return 0;
/* Allowed if parent directory and link owner match. */
- puid = parent->i_uid;
- if (uid_valid(puid) && uid_eq(puid, inode->i_uid))
+ if (uid_valid(nd->dir_uid) && uid_eq(nd->dir_uid, inode->i_uid))
return 0;
if (nd->flags & LOOKUP_RCU)
@@ -1113,63 +1075,6 @@ static int may_create_in_sticky(umode_t dir_mode, kuid_t dir_uid,
return 0;
}
-static __always_inline
-const char *get_link(struct nameidata *nd)
-{
- struct saved *last = nd->stack + nd->depth - 1;
- struct dentry *dentry = last->link.dentry;
- struct inode *inode = nd->link_inode;
- int error;
- const char *res;
-
- if (unlikely(nd->flags & LOOKUP_NO_SYMLINKS))
- return ERR_PTR(-ELOOP);
-
- if (!(nd->flags & LOOKUP_RCU)) {
- touch_atime(&last->link);
- cond_resched();
- } else if (atime_needs_update(&last->link, inode)) {
- if (unlikely(unlazy_walk(nd)))
- return ERR_PTR(-ECHILD);
- touch_atime(&last->link);
- }
-
- error = security_inode_follow_link(dentry, inode,
- nd->flags & LOOKUP_RCU);
- if (unlikely(error))
- return ERR_PTR(error);
-
- nd->last_type = LAST_BIND;
- res = READ_ONCE(inode->i_link);
- if (!res) {
- const char * (*get)(struct dentry *, struct inode *,
- struct delayed_call *);
- get = inode->i_op->get_link;
- if (nd->flags & LOOKUP_RCU) {
- res = get(NULL, inode, &last->done);
- if (res == ERR_PTR(-ECHILD)) {
- if (unlikely(unlazy_walk(nd)))
- return ERR_PTR(-ECHILD);
- res = get(dentry, inode, &last->done);
- }
- } else {
- res = get(dentry, inode, &last->done);
- }
- if (IS_ERR_OR_NULL(res))
- return res;
- }
- if (*res == '/') {
- error = nd_jump_root(nd);
- if (unlikely(error))
- return ERR_PTR(error);
- while (unlikely(*++res == '/'))
- ;
- }
- if (!*res)
- res = NULL;
- return res;
-}
-
/*
* follow_up - Find the mountpoint of path's vfsmount
*
@@ -1203,19 +1108,59 @@ int follow_up(struct path *path)
}
EXPORT_SYMBOL(follow_up);
+static bool choose_mountpoint_rcu(struct mount *m, const struct path *root,
+ struct path *path, unsigned *seqp)
+{
+ while (mnt_has_parent(m)) {
+ struct dentry *mountpoint = m->mnt_mountpoint;
+
+ m = m->mnt_parent;
+ if (unlikely(root->dentry == mountpoint &&
+ root->mnt == &m->mnt))
+ break;
+ if (mountpoint != m->mnt.mnt_root) {
+ path->mnt = &m->mnt;
+ path->dentry = mountpoint;
+ *seqp = read_seqcount_begin(&mountpoint->d_seq);
+ return true;
+ }
+ }
+ return false;
+}
+
+static bool choose_mountpoint(struct mount *m, const struct path *root,
+ struct path *path)
+{
+ bool found;
+
+ rcu_read_lock();
+ while (1) {
+ unsigned seq, mseq = read_seqbegin(&mount_lock);
+
+ found = choose_mountpoint_rcu(m, root, path, &seq);
+ if (unlikely(!found)) {
+ if (!read_seqretry(&mount_lock, mseq))
+ break;
+ } else {
+ if (likely(__legitimize_path(path, seq, mseq)))
+ break;
+ rcu_read_unlock();
+ path_put(path);
+ rcu_read_lock();
+ }
+ }
+ rcu_read_unlock();
+ return found;
+}
+
/*
* Perform an automount
* - return -EISDIR to tell follow_managed() to stop and return the path we
* were called with.
*/
-static int follow_automount(struct path *path, struct nameidata *nd,
- bool *need_mntput)
+static int follow_automount(struct path *path, int *count, unsigned lookup_flags)
{
- struct vfsmount *mnt;
- int err;
-
- if (!path->dentry->d_op || !path->dentry->d_op->d_automount)
- return -EREMOTE;
+ struct dentry *dentry = path->dentry;
/* We don't want to mount if someone's just doing a stat -
* unless they're stat'ing a directory and appended a '/' to
@@ -1228,138 +1173,91 @@ static int follow_automount(struct path *path, struct nameidata *nd,
* as being automount points. These will need the attentions
* of the daemon to instantiate them before they can be used.
*/
- if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY |
+ if (!(lookup_flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY |
LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) &&
- path->dentry->d_inode)
+ dentry->d_inode)
return -EISDIR;
- nd->total_link_count++;
- if (nd->total_link_count >= 40)
+ if (count && (*count)++ >= MAXSYMLINKS)
return -ELOOP;
- mnt = path->dentry->d_op->d_automount(path);
- if (IS_ERR(mnt)) {
- /*
- * The filesystem is allowed to return -EISDIR here to indicate
- * it doesn't want to automount. For instance, autofs would do
- * this so that its userspace daemon can mount on this dentry.
- *
- * However, we can only permit this if it's a terminal point in
- * the path being looked up; if it wasn't then the remainder of
- * the path is inaccessible and we should say so.
- */
- if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT))
- return -EREMOTE;
- return PTR_ERR(mnt);
- }
-
- if (!mnt) /* mount collision */
- return 0;
-
- if (!*need_mntput) {
- /* lock_mount() may release path->mnt on error */
- mntget(path->mnt);
- *need_mntput = true;
- }
- err = finish_automount(mnt, path);
-
- switch (err) {
- case -EBUSY:
- /* Someone else made a mount here whilst we were busy */
- return 0;
- case 0:
- path_put(path);
- path->mnt = mnt;
- path->dentry = dget(mnt->mnt_root);
- return 0;
- default:
- return err;
- }
-
+ return finish_automount(dentry->d_op->d_automount(path), path);
}
/*
- * Handle a dentry that is managed in some way.
- * - Flagged for transit management (autofs)
- * - Flagged as mountpoint
- * - Flagged as automount point
- *
- * This may only be called in refwalk mode.
- * On success path->dentry is known positive.
- *
- * Serialization is taken care of in namespace.c
+ * mount traversal - out-of-line part. One note on ->d_flags accesses -
+ * dentries are pinned but not locked here, so negative dentry can go
+ * positive right under us. Use of smp_load_acquire() provides a barrier
+ * sufficient for ->d_inode and ->d_flags consistency.
*/
-static int follow_managed(struct path *path, struct nameidata *nd)
+static int __traverse_mounts(struct path *path, unsigned flags, bool *jumped,
+ int *count, unsigned lookup_flags)
{
- struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */
- unsigned flags;
+ struct vfsmount *mnt = path->mnt;
bool need_mntput = false;
int ret = 0;
- /* Given that we're not holding a lock here, we retain the value in a
- * local variable for each dentry as we look at it so that we don't see
- * the components of that value change under us */
- while (flags = smp_load_acquire(&path->dentry->d_flags),
- unlikely(flags & DCACHE_MANAGED_DENTRY)) {
+ while (flags & DCACHE_MANAGED_DENTRY) {
/* Allow the filesystem to manage the transit without i_mutex
* being held. */
if (flags & DCACHE_MANAGE_TRANSIT) {
- BUG_ON(!path->dentry->d_op);
- BUG_ON(!path->dentry->d_op->d_manage);
ret = path->dentry->d_op->d_manage(path, false);
flags = smp_load_acquire(&path->dentry->d_flags);
if (ret < 0)
break;
}
- /* Transit to a mounted filesystem. */
- if (flags & DCACHE_MOUNTED) {
+ if (flags & DCACHE_MOUNTED) { // something's mounted on it..
struct vfsmount *mounted = lookup_mnt(path);
- if (mounted) {
+ if (mounted) { // ... in our namespace
dput(path->dentry);
if (need_mntput)
mntput(path->mnt);
path->mnt = mounted;
path->dentry = dget(mounted->mnt_root);
+ // here we know it's positive
+ flags = path->dentry->d_flags;
need_mntput = true;
continue;
}
-
- /* Something is mounted on this dentry in another
- * namespace and/or whatever was mounted there in this
- * namespace got unmounted before lookup_mnt() could
- * get it */
}
- /* Handle an automount point */
- if (flags & DCACHE_NEED_AUTOMOUNT) {
- ret = follow_automount(path, nd, &need_mntput);
- if (ret < 0)
- break;
- continue;
- }
+ if (!(flags & DCACHE_NEED_AUTOMOUNT))
+ break;
- /* We didn't change the current path point */
- break;
+ // uncovered automount point
+ ret = follow_automount(path, count, lookup_flags);
+ flags = smp_load_acquire(&path->dentry->d_flags);
+ if (ret < 0)
+ break;
}
- if (need_mntput) {
- if (path->mnt == mnt)
- mntput(path->mnt);
- if (unlikely(nd->flags & LOOKUP_NO_XDEV))
- ret = -EXDEV;
- else
- nd->flags |= LOOKUP_JUMPED;
- }
- if (ret == -EISDIR || !ret)
- ret = 1;
- if (ret > 0 && unlikely(d_flags_negative(flags)))
+ if (ret == -EISDIR)
+ ret = 0;
+ // possible if you race with several mount --move
+ if (need_mntput && path->mnt == mnt)
+ mntput(path->mnt);
+ if (!ret && unlikely(d_flags_negative(flags)))
ret = -ENOENT;
- if (unlikely(ret < 0))
- path_put_conditional(path, nd);
+ *jumped = need_mntput;
return ret;
}
+static inline int traverse_mounts(struct path *path, bool *jumped,
+ int *count, unsigned lookup_flags)
+{
+ unsigned flags = smp_load_acquire(&path->dentry->d_flags);
+
+ /* fastpath */
+ if (likely(!(flags & DCACHE_MANAGED_DENTRY))) {
+ *jumped = false;
+ if (unlikely(d_flags_negative(flags)))
+ return -ENOENT;
+ return 0;
+ }
+ return __traverse_mounts(path, flags, jumped, count, lookup_flags);
+}
+
int follow_down_one(struct path *path)
{
struct vfsmount *mounted;
@@ -1376,11 +1274,22 @@ int follow_down_one(struct path *path)
}
EXPORT_SYMBOL(follow_down_one);
-static inline int managed_dentry_rcu(const struct path *path)
+/*
+ * Follow down to the covering mount currently visible to userspace. At each
+ * point, the filesystem owning that dentry may be queried as to whether the
+ * caller is permitted to proceed or not.
+ */
+int follow_down(struct path *path)
{
- return (path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) ?
- path->dentry->d_op->d_manage(path, true) : 0;
+ struct vfsmount *mnt = path->mnt;
+ bool jumped;
+ int ret = traverse_mounts(path, &jumped, NULL, 0);
+
+ if (path->mnt != mnt)
+ mntput(mnt);
+ return ret;
}
+EXPORT_SYMBOL(follow_down);
/*
* Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
@@ -1389,204 +1298,88 @@ static inline int managed_dentry_rcu(const struct path *path)
static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
struct inode **inode, unsigned *seqp)
{
+ struct dentry *dentry = path->dentry;
+ unsigned int flags = dentry->d_flags;
+
+ if (likely(!(flags & DCACHE_MANAGED_DENTRY)))
+ return true;
+
+ if (unlikely(nd->flags & LOOKUP_NO_XDEV))
+ return false;
+
for (;;) {
- struct mount *mounted;
/*
* Don't forget we might have a non-mountpoint managed dentry
* that wants to block transit.
*/
- switch (managed_dentry_rcu(path)) {
- case -ECHILD:
- default:
- return false;
- case -EISDIR:
- return true;
- case 0:
- break;
- }
-
- if (!d_mountpoint(path->dentry))
- return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT);
-
- mounted = __lookup_mnt(path->mnt, path->dentry);
- if (!mounted)
- break;
- if (unlikely(nd->flags & LOOKUP_NO_XDEV))
- return false;
- path->mnt = &mounted->mnt;
- path->dentry = mounted->mnt.mnt_root;
- nd->flags |= LOOKUP_JUMPED;
- *seqp = read_seqcount_begin(&path->dentry->d_seq);
- /*
- * Update the inode too. We don't need to re-check the
- * dentry sequence number here after this d_inode read,
- * because a mount-point is always pinned.
- */
- *inode = path->dentry->d_inode;
- }
- return !read_seqretry(&mount_lock, nd->m_seq) &&
- !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT);
-}
-
-static int follow_dotdot_rcu(struct nameidata *nd)
-{
- struct inode *inode = nd->inode;
-
- while (1) {
- if (path_equal(&nd->path, &nd->root)) {
- if (unlikely(nd->flags & LOOKUP_BENEATH))
- return -ECHILD;
- break;
+ if (unlikely(flags & DCACHE_MANAGE_TRANSIT)) {
+ int res = dentry->d_op->d_manage(path, true);
+ if (res)
+ return res == -EISDIR;
+ flags = dentry->d_flags;
}
- if (nd->path.dentry != nd->path.mnt->mnt_root) {
- struct dentry *old = nd->path.dentry;
- struct dentry *parent = old->d_parent;
- unsigned seq;
- inode = parent->d_inode;
- seq = read_seqcount_begin(&parent->d_seq);
- if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq)))
- return -ECHILD;
- nd->path.dentry = parent;
- nd->seq = seq;
- if (unlikely(!path_connected(&nd->path)))
- return -ECHILD;
- break;
- } else {
- struct mount *mnt = real_mount(nd->path.mnt);
- struct mount *mparent = mnt->mnt_parent;
- struct dentry *mountpoint = mnt->mnt_mountpoint;
- struct inode *inode2 = mountpoint->d_inode;
- unsigned seq = read_seqcount_begin(&mountpoint->d_seq);
- if (unlikely(read_seqretry(&mount_lock, nd->m_seq)))
- return -ECHILD;
- if (&mparent->mnt == nd->path.mnt)
- break;
- if (unlikely(nd->flags & LOOKUP_NO_XDEV))
- return -ECHILD;
- /* we know that mountpoint was pinned */
- nd->path.dentry = mountpoint;
- nd->path.mnt = &mparent->mnt;
- inode = inode2;
- nd->seq = seq;
+ if (flags & DCACHE_MOUNTED) {
+ struct mount *mounted = __lookup_mnt(path->mnt, dentry);
+ if (mounted) {
+ path->mnt = &mounted->mnt;
+ dentry = path->dentry = mounted->mnt.mnt_root;
+ nd->flags |= LOOKUP_JUMPED;
+ *seqp = read_seqcount_begin(&dentry->d_seq);
+ *inode = dentry->d_inode;
+ /*
+ * We don't need to re-check ->d_seq after this
+ * ->d_inode read - there will be an RCU delay
+ * between mount hash removal and ->mnt_root
+ * becoming unpinned.
+ */
+ flags = dentry->d_flags;
+ continue;
+ }
+ if (read_seqretry(&mount_lock, nd->m_seq))
+ return false;
}
+ return !(flags & DCACHE_NEED_AUTOMOUNT);
}
- while (unlikely(d_mountpoint(nd->path.dentry))) {
- struct mount *mounted;
- mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry);
- if (unlikely(read_seqretry(&mount_lock, nd->m_seq)))
- return -ECHILD;
- if (!mounted)
- break;
- if (unlikely(nd->flags & LOOKUP_NO_XDEV))
- return -ECHILD;
- nd->path.mnt = &mounted->mnt;
- nd->path.dentry = mounted->mnt.mnt_root;
- inode = nd->path.dentry->d_inode;
- nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
- }
- nd->inode = inode;
- return 0;
}
-/*
- * Follow down to the covering mount currently visible to userspace. At each
- * point, the filesystem owning that dentry may be queried as to whether the
- * caller is permitted to proceed or not.
- */
-int follow_down(struct path *path)
+static inline int handle_mounts(struct nameidata *nd, struct dentry *dentry,
+ struct path *path, struct inode **inode,
+ unsigned int *seqp)
{
- unsigned managed;
+ bool jumped;
int ret;
- while (managed = READ_ONCE(path->dentry->d_flags),
- unlikely(managed & DCACHE_MANAGED_DENTRY)) {
- /* Allow the filesystem to manage the transit without i_mutex
- * being held.
- *
- * We indicate to the filesystem if someone is trying to mount
- * something here. This gives autofs the chance to deny anyone
- * other than its daemon the right to mount on its
- * superstructure.
- *
- * The filesystem may sleep at this point.
- */
- if (managed & DCACHE_MANAGE_TRANSIT) {
- BUG_ON(!path->dentry->d_op);
- BUG_ON(!path->dentry->d_op->d_manage);
- ret = path->dentry->d_op->d_manage(path, false);
- if (ret < 0)
- return ret == -EISDIR ? 0 : ret;
- }
-
- /* Transit to a mounted filesystem. */
- if (managed & DCACHE_MOUNTED) {
- struct vfsmount *mounted = lookup_mnt(path);
- if (!mounted)
- break;
- dput(path->dentry);
- mntput(path->mnt);
- path->mnt = mounted;
- path->dentry = dget(mounted->mnt_root);
- continue;
- }
-
- /* Don't handle automount points here */
- break;
- }
- return 0;
-}
-EXPORT_SYMBOL(follow_down);
-
-/*
- * Skip to top of mountpoint pile in refwalk mode for follow_dotdot()
- */
-static void follow_mount(struct path *path)
-{
- while (d_mountpoint(path->dentry)) {
- struct vfsmount *mounted = lookup_mnt(path);
- if (!mounted)
- break;
- dput(path->dentry);
- mntput(path->mnt);
- path->mnt = mounted;
- path->dentry = dget(mounted->mnt_root);
+ path->mnt = nd->path.mnt;
+ path->dentry = dentry;
+ if (nd->flags & LOOKUP_RCU) {
+ unsigned int seq = *seqp;
+ if (unlikely(!*inode))
+ return -ENOENT;
+ if (likely(__follow_mount_rcu(nd, path, inode, seqp)))
+ return 0;
+ if (unlazy_child(nd, dentry, seq))
+ return -ECHILD;
+ // *path might've been clobbered by __follow_mount_rcu()
+ path->mnt = nd->path.mnt;
+ path->dentry = dentry;
}
-}
-
-static int path_parent_directory(struct path *path)
-{
- struct dentry *old = path->dentry;
- /* rare case of legitimate dget_parent()... */
- path->dentry = dget_parent(path->dentry);
- dput(old);
- if (unlikely(!path_connected(path)))
- return -ENOENT;
- return 0;
-}
-
-static int follow_dotdot(struct nameidata *nd)
-{
- while (1) {
- if (path_equal(&nd->path, &nd->root)) {
- if (unlikely(nd->flags & LOOKUP_BENEATH))
- return -EXDEV;
- break;
- }
- if (nd->path.dentry != nd->path.mnt->mnt_root) {
- int ret = path_parent_directory(&nd->path);
- if (ret)
- return ret;
- break;
- }
- if (!follow_up(&nd->path))
- break;
+ ret = traverse_mounts(path, &jumped, &nd->total_link_count, nd->flags);
+ if (jumped) {
if (unlikely(nd->flags & LOOKUP_NO_XDEV))
- return -EXDEV;
+ ret = -EXDEV;
+ else
+ nd->flags |= LOOKUP_JUMPED;
}
- follow_mount(&nd->path);
- nd->inode = nd->path.dentry->d_inode;
- return 0;
+ if (unlikely(ret)) {
+ dput(path->dentry);
+ if (path->mnt != nd->path.mnt)
+ mntput(path->mnt);
+ } else {
+ *inode = d_backing_inode(path->dentry);
+ *seqp = 0; /* out of RCU mode, so the value doesn't matter */
+ }
+ return ret;
}
/*
@@ -1643,14 +1436,12 @@ static struct dentry *__lookup_hash(const struct qstr *name,
return dentry;
}
-static int lookup_fast(struct nameidata *nd,
- struct path *path, struct inode **inode,
- unsigned *seqp)
+static struct dentry *lookup_fast(struct nameidata *nd,
+ struct inode **inode,
+ unsigned *seqp)
{
- struct vfsmount *mnt = nd->path.mnt;
struct dentry *dentry, *parent = nd->path.dentry;
int status = 1;
- int err;
/*
* Rename seqlock is not required here because in the off chance
@@ -1659,12 +1450,11 @@ static int lookup_fast(struct nameidata *nd,
*/
if (nd->flags & LOOKUP_RCU) {
unsigned seq;
- bool negative;
dentry = __d_lookup_rcu(parent, &nd->last, &seq);
if (unlikely(!dentry)) {
if (unlazy_walk(nd))
- return -ECHILD;
- return 0;
+ return ERR_PTR(-ECHILD);
+ return NULL;
}
/*
@@ -1672,9 +1462,8 @@ static int lookup_fast(struct nameidata *nd,
* the dentry name information from lookup.
*/
*inode = d_backing_inode(dentry);
- negative = d_is_negative(dentry);
if (unlikely(read_seqcount_retry(&dentry->d_seq, seq)))
- return -ECHILD;
+ return ERR_PTR(-ECHILD);
/*
* This sequence count validates that the parent had no
@@ -1684,46 +1473,30 @@ static int lookup_fast(struct nameidata *nd,
* enough, we can use __read_seqcount_retry here.
*/
if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq)))
- return -ECHILD;
+ return ERR_PTR(-ECHILD);
*seqp = seq;
status = d_revalidate(dentry, nd->flags);
- if (likely(status > 0)) {
- /*
- * Note: do negative dentry check after revalidation in
- * case that drops it.
- */
- if (unlikely(negative))
- return -ENOENT;
- path->mnt = mnt;
- path->dentry = dentry;
- if (likely(__follow_mount_rcu(nd, path, inode, seqp)))
- return 1;
- }
+ if (likely(status > 0))
+ return dentry;
if (unlazy_child(nd, dentry, seq))
- return -ECHILD;
+ return ERR_PTR(-ECHILD);
if (unlikely(status == -ECHILD))
/* we'd been told to redo it in non-rcu mode */
status = d_revalidate(dentry, nd->flags);
} else {
dentry = __d_lookup(parent, &nd->last);
if (unlikely(!dentry))
- return 0;
+ return NULL;
status = d_revalidate(dentry, nd->flags);
}
if (unlikely(status <= 0)) {
if (!status)
d_invalidate(dentry);
dput(dentry);
- return status;
+ return ERR_PTR(status);
}
-
- path->mnt = mnt;
- path->dentry = dentry;
- err = follow_managed(path, nd);
- if (likely(err > 0))
- *inode = d_backing_inode(path->dentry);
- return err;
+ return dentry;
}
/* Fast lookup failed, do it the slow way */
@@ -1788,81 +1561,107 @@ static inline int may_lookup(struct nameidata *nd)
return inode_permission(nd->inode, MAY_EXEC);
}
-static inline int handle_dots(struct nameidata *nd, int type)
+static int reserve_stack(struct nameidata *nd, struct path *link, unsigned seq)
{
- if (type == LAST_DOTDOT) {
- int error = 0;
+ if (unlikely(nd->total_link_count++ >= MAXSYMLINKS))
+ return -ELOOP;
- if (!nd->root.mnt) {
- error = set_root(nd);
- if (error)
- return error;
- }
- if (nd->flags & LOOKUP_RCU)
- error = follow_dotdot_rcu(nd);
- else
- error = follow_dotdot(nd);
- if (error)
- return error;
+ if (likely(nd->depth != EMBEDDED_LEVELS))
+ return 0;
+ if (likely(nd->stack != nd->internal))
+ return 0;
+ if (likely(nd_alloc_stack(nd)))
+ return 0;
- if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) {
- /*
- * If there was a racing rename or mount along our
- * path, then we can't be sure that ".." hasn't jumped
- * above nd->root (and so userspace should retry or use
- * some fallback).
- */
- smp_rmb();
- if (unlikely(__read_seqcount_retry(&mount_lock.seqcount, nd->m_seq)))
- return -EAGAIN;
- if (unlikely(__read_seqcount_retry(&rename_lock.seqcount, nd->r_seq)))
- return -EAGAIN;
- }
+ if (nd->flags & LOOKUP_RCU) {
+ // we need to grab link before we do unlazy. And we can't skip
+ // unlazy even if we fail to grab the link - cleanup needs it
+ bool grabbed_link = legitimize_path(nd, link, seq);
+
+ if (unlazy_walk(nd) != 0 || !grabbed_link)
+ return -ECHILD;
+
+ if (nd_alloc_stack(nd))
+ return 0;
}
- return 0;
+ return -ENOMEM;
}
-static int pick_link(struct nameidata *nd, struct path *link,
- struct inode *inode, unsigned seq)
+enum {WALK_TRAILING = 1, WALK_MORE = 2, WALK_NOFOLLOW = 4};
+
+static const char *pick_link(struct nameidata *nd, struct path *link,
+ struct inode *inode, unsigned seq, int flags)
{
- int error;
struct saved *last;
- if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) {
- path_to_nameidata(link, nd);
- return -ELOOP;
- }
- if (!(nd->flags & LOOKUP_RCU)) {
- if (link->mnt == nd->path.mnt)
- mntget(link->mnt);
- }
- error = nd_alloc_stack(nd);
+ const char *res;
+ int error = reserve_stack(nd, link, seq);
+
if (unlikely(error)) {
- if (error == -ECHILD) {
- if (unlikely(!legitimize_path(nd, link, seq))) {
- drop_links(nd);
- nd->depth = 0;
- nd->flags &= ~LOOKUP_RCU;
- nd->path.mnt = NULL;
- nd->path.dentry = NULL;
- rcu_read_unlock();
- } else if (likely(unlazy_walk(nd)) == 0)
- error = nd_alloc_stack(nd);
- }
- if (error) {
+ if (!(nd->flags & LOOKUP_RCU))
path_put(link);
- return error;
- }
+ return ERR_PTR(error);
}
-
last = nd->stack + nd->depth++;
last->link = *link;
clear_delayed_call(&last->done);
- nd->link_inode = inode;
last->seq = seq;
- return 1;
-}
-enum {WALK_FOLLOW = 1, WALK_MORE = 2};
+ if (flags & WALK_TRAILING) {
+ error = may_follow_link(nd, inode);
+ if (unlikely(error))
+ return ERR_PTR(error);
+ }
+
+ if (unlikely(nd->flags & LOOKUP_NO_SYMLINKS))
+ return ERR_PTR(-ELOOP);
+
+ if (!(nd->flags & LOOKUP_RCU)) {
+ touch_atime(&last->link);
+ cond_resched();
+ } else if (atime_needs_update(&last->link, inode)) {
+ if (unlikely(unlazy_walk(nd)))
+ return ERR_PTR(-ECHILD);
+ touch_atime(&last->link);
+ }
+
+ error = security_inode_follow_link(link->dentry, inode,
+ nd->flags & LOOKUP_RCU);
+ if (unlikely(error))
+ return ERR_PTR(error);
+
+ res = READ_ONCE(inode->i_link);
+ if (!res) {
+ const char * (*get)(struct dentry *, struct inode *,
+ struct delayed_call *);
+ get = inode->i_op->get_link;
+ if (nd->flags & LOOKUP_RCU) {
+ res = get(NULL, inode, &last->done);
+ if (res == ERR_PTR(-ECHILD)) {
+ if (unlikely(unlazy_walk(nd)))
+ return ERR_PTR(-ECHILD);
+ res = get(link->dentry, inode, &last->done);
+ }
+ } else {
+ res = get(link->dentry, inode, &last->done);
+ }
+ if (!res)
+ goto all_done;
+ if (IS_ERR(res))
+ return res;
+ }
+ if (*res == '/') {
+ error = nd_jump_root(nd);
+ if (unlikely(error))
+ return ERR_PTR(error);
+ while (unlikely(*++res == '/'))
+ ;
+ }
+ if (*res)
+ return res;
+all_done: // pure jump
+ put_link(nd);
+ return NULL;
+}
/*
* Do we need to follow links? We _really_ want to be able
@@ -1870,63 +1669,187 @@ enum {WALK_FOLLOW = 1, WALK_MORE = 2};
* so we keep a cache of "no, this doesn't need follow_link"
* for the common case.
*/
-static inline int step_into(struct nameidata *nd, struct path *path,
- int flags, struct inode *inode, unsigned seq)
+static const char *step_into(struct nameidata *nd, int flags,
+ struct dentry *dentry, struct inode *inode, unsigned seq)
{
- if (!(flags & WALK_MORE) && nd->depth)
- put_link(nd);
- if (likely(!d_is_symlink(path->dentry)) ||
- !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW)) {
+ struct path path;
+ int err = handle_mounts(nd, dentry, &path, &inode, &seq);
+
+ if (err < 0)
+ return ERR_PTR(err);
+ if (likely(!d_is_symlink(path.dentry)) ||
+ ((flags & WALK_TRAILING) && !(nd->flags & LOOKUP_FOLLOW)) ||
+ (flags & WALK_NOFOLLOW)) {
/* not a symlink or should not follow */
- path_to_nameidata(path, nd);
+ if (!(nd->flags & LOOKUP_RCU)) {
+ dput(nd->path.dentry);
+ if (nd->path.mnt != path.mnt)
+ mntput(nd->path.mnt);
+ }
+ nd->path = path;
nd->inode = inode;
nd->seq = seq;
- return 0;
+ return NULL;
}
- /* make sure that d_is_symlink above matches inode */
if (nd->flags & LOOKUP_RCU) {
- if (read_seqcount_retry(&path->dentry->d_seq, seq))
- return -ECHILD;
+ /* make sure that d_is_symlink above matches inode */
+ if (read_seqcount_retry(&path.dentry->d_seq, seq))
+ return ERR_PTR(-ECHILD);
+ } else {
+ if (path.mnt == nd->path.mnt)
+ mntget(path.mnt);
}
- return pick_link(nd, path, inode, seq);
+ return pick_link(nd, &path, inode, seq, flags);
}
-static int walk_component(struct nameidata *nd, int flags)
+static struct dentry *follow_dotdot_rcu(struct nameidata *nd,
+ struct inode **inodep,
+ unsigned *seqp)
{
- struct path path;
+ struct dentry *parent, *old;
+
+ if (path_equal(&nd->path, &nd->root))
+ goto in_root;
+ if (unlikely(nd->path.dentry == nd->path.mnt->mnt_root)) {
+ struct path path;
+ unsigned seq;
+ if (!choose_mountpoint_rcu(real_mount(nd->path.mnt),
+ &nd->root, &path, &seq))
+ goto in_root;
+ if (unlikely(nd->flags & LOOKUP_NO_XDEV))
+ return ERR_PTR(-ECHILD);
+ nd->path = path;
+ nd->inode = path.dentry->d_inode;
+ nd->seq = seq;
+ if (unlikely(read_seqretry(&mount_lock, nd->m_seq)))
+ return ERR_PTR(-ECHILD);
+ /* we know that mountpoint was pinned */
+ }
+ old = nd->path.dentry;
+ parent = old->d_parent;
+ *inodep = parent->d_inode;
+ *seqp = read_seqcount_begin(&parent->d_seq);
+ if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq)))
+ return ERR_PTR(-ECHILD);
+ if (unlikely(!path_connected(nd->path.mnt, parent)))
+ return ERR_PTR(-ECHILD);
+ return parent;
+in_root:
+ if (unlikely(read_seqretry(&mount_lock, nd->m_seq)))
+ return ERR_PTR(-ECHILD);
+ if (unlikely(nd->flags & LOOKUP_BENEATH))
+ return ERR_PTR(-ECHILD);
+ return NULL;
+}
+
+static struct dentry *follow_dotdot(struct nameidata *nd,
+ struct inode **inodep,
+ unsigned *seqp)
+{
+ struct dentry *parent;
+
+ if (path_equal(&nd->path, &nd->root))
+ goto in_root;
+ if (unlikely(nd->path.dentry == nd->path.mnt->mnt_root)) {
+ struct path path;
+
+ if (!choose_mountpoint(real_mount(nd->path.mnt),
+ &nd->root, &path))
+ goto in_root;
+ path_put(&nd->path);
+ nd->path = path;
+ nd->inode = path.dentry->d_inode;
+ if (unlikely(nd->flags & LOOKUP_NO_XDEV))
+ return ERR_PTR(-EXDEV);
+ }
+ /* rare case of legitimate dget_parent()... */
+ parent = dget_parent(nd->path.dentry);
+ if (unlikely(!path_connected(nd->path.mnt, parent))) {
+ dput(parent);
+ return ERR_PTR(-ENOENT);
+ }
+ *seqp = 0;
+ *inodep = parent->d_inode;
+ return parent;
+
+in_root:
+ if (unlikely(nd->flags & LOOKUP_BENEATH))
+ return ERR_PTR(-EXDEV);
+ dget(nd->path.dentry);
+ return NULL;
+}
+
+static const char *handle_dots(struct nameidata *nd, int type)
+{
+ if (type == LAST_DOTDOT) {
+ const char *error = NULL;
+ struct dentry *parent;
+ struct inode *inode;
+ unsigned seq;
+
+ if (!nd->root.mnt) {
+ error = ERR_PTR(set_root(nd));
+ if (error)
+ return error;
+ }
+ if (nd->flags & LOOKUP_RCU)
+ parent = follow_dotdot_rcu(nd, &inode, &seq);
+ else
+ parent = follow_dotdot(nd, &inode, &seq);
+ if (IS_ERR(parent))
+ return ERR_CAST(parent);
+ if (unlikely(!parent))
+ error = step_into(nd, WALK_NOFOLLOW,
+ nd->path.dentry, nd->inode, nd->seq);
+ else
+ error = step_into(nd, WALK_NOFOLLOW,
+ parent, inode, seq);
+ if (unlikely(error))
+ return error;
+
+ if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) {
+ /*
+ * If there was a racing rename or mount along our
+ * path, then we can't be sure that ".." hasn't jumped
+ * above nd->root (and so userspace should retry or use
+ * some fallback).
+ */
+ smp_rmb();
+ if (unlikely(__read_seqcount_retry(&mount_lock.seqcount, nd->m_seq)))
+ return ERR_PTR(-EAGAIN);
+ if (unlikely(__read_seqcount_retry(&rename_lock.seqcount, nd->r_seq)))
+ return ERR_PTR(-EAGAIN);
+ }
+ }
+ return NULL;
+}
+
+static const char *walk_component(struct nameidata *nd, int flags)
+{
+ struct dentry *dentry;
struct inode *inode;
unsigned seq;
- int err;
/*
* "." and ".." are special - ".." especially so because it has
* to be able to know about the current root directory and
* parent relationships.
*/
if (unlikely(nd->last_type != LAST_NORM)) {
- err = handle_dots(nd, nd->last_type);
if (!(flags & WALK_MORE) && nd->depth)
put_link(nd);
- return err;
+ return handle_dots(nd, nd->last_type);
}
- err = lookup_fast(nd, &path, &inode, &seq);
- if (unlikely(err <= 0)) {
- if (err < 0)
- return err;
- path.dentry = lookup_slow(&nd->last, nd->path.dentry,
- nd->flags);
- if (IS_ERR(path.dentry))
- return PTR_ERR(path.dentry);
-
- path.mnt = nd->path.mnt;
- err = follow_managed(&path, nd);
- if (unlikely(err < 0))
- return err;
-
- seq = 0; /* we are already out of RCU mode */
- inode = d_backing_inode(path.dentry);
+ dentry = lookup_fast(nd, &inode, &seq);
+ if (IS_ERR(dentry))
+ return ERR_CAST(dentry);
+ if (unlikely(!dentry)) {
+ dentry = lookup_slow(&nd->last, nd->path.dentry, nd->flags);
+ if (IS_ERR(dentry))
+ return ERR_CAST(dentry);
}
-
- return step_into(nd, &path, flags, inode, seq);
+ if (!(flags & WALK_MORE) && nd->depth)
+ put_link(nd);
+ return step_into(nd, flags, dentry, inode, seq);
}
/*
@@ -2167,8 +2090,11 @@ static inline u64 hash_name(const void *salt, const char *name)
*/
static int link_path_walk(const char *name, struct nameidata *nd)
{
+ int depth = 0; // depth <= nd->depth
int err;
+ nd->last_type = LAST_ROOT;
+ nd->flags |= LOOKUP_PARENT;
if (IS_ERR(name))
return PTR_ERR(name);
while (*name=='/')
@@ -2178,6 +2104,7 @@ static int link_path_walk(const char *name, struct nameidata *nd)
/* At this point we know we have a real path component. */
for(;;) {
+ const char *link;
u64 hash_len;
int type;
@@ -2227,36 +2154,27 @@ static int link_path_walk(const char *name, struct nameidata *nd)
} while (unlikely(*name == '/'));
if (unlikely(!*name)) {
OK:
- /* pathname body, done */
- if (!nd->depth)
- return 0;
- name = nd->stack[nd->depth - 1].name;
- /* trailing symlink, done */
- if (!name)
+ /* pathname or trailing symlink, done */
+ if (!depth) {
+ nd->dir_uid = nd->inode->i_uid;
+ nd->dir_mode = nd->inode->i_mode;
+ nd->flags &= ~LOOKUP_PARENT;
return 0;
+ }
/* last component of nested symlink */
- err = walk_component(nd, WALK_FOLLOW);
+ name = nd->stack[--depth].name;
+ link = walk_component(nd, 0);
} else {
/* not the last component */
- err = walk_component(nd, WALK_FOLLOW | WALK_MORE);
+ link = walk_component(nd, WALK_MORE);
}
- if (err < 0)
- return err;
-
- if (err) {
- const char *s = get_link(nd);
-
- if (IS_ERR(s))
- return PTR_ERR(s);
- err = 0;
- if (unlikely(!s)) {
- /* jumped */
- put_link(nd);
- } else {
- nd->stack[nd->depth - 1].name = name;
- name = s;
- continue;
- }
+ if (unlikely(link)) {
+ if (IS_ERR(link))
+ return PTR_ERR(link);
+ /* a symlink to follow */
+ nd->stack[depth++].name = name;
+ name = link;
+ continue;
}
if (unlikely(!d_can_lookup(nd->path.dentry))) {
if (nd->flags & LOOKUP_RCU) {
@@ -2279,8 +2197,7 @@ static const char *path_init(struct nameidata *nd, unsigned flags)
if (flags & LOOKUP_RCU)
rcu_read_lock();
- nd->last_type = LAST_ROOT; /* if there are only slashes... */
- nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT;
+ nd->flags = flags | LOOKUP_JUMPED;
nd->depth = 0;
nd->m_seq = __read_seqcount_begin(&mount_lock.seqcount);
@@ -2370,54 +2287,20 @@ static const char *path_init(struct nameidata *nd, unsigned flags)
return s;
}
-static const char *trailing_symlink(struct nameidata *nd)
-{
- const char *s;
- int error = may_follow_link(nd);
- if (unlikely(error))
- return ERR_PTR(error);
- nd->flags |= LOOKUP_PARENT;
- nd->stack[0].name = NULL;
- s = get_link(nd);
- return s ? s : "";
-}
-
-static inline int lookup_last(struct nameidata *nd)
+static inline const char *lookup_last(struct nameidata *nd)
{
if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len])
nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
- nd->flags &= ~LOOKUP_PARENT;
- return walk_component(nd, 0);
+ return walk_component(nd, WALK_TRAILING);
}
static int handle_lookup_down(struct nameidata *nd)
{
- struct path path = nd->path;
- struct inode *inode = nd->inode;
- unsigned seq = nd->seq;
- int err;
-
- if (nd->flags & LOOKUP_RCU) {
- /*
- * don't bother with unlazy_walk on failure - we are
- * at the very beginning of walk, so we lose nothing
- * if we simply redo everything in non-RCU mode
- */
- if (unlikely(!__follow_mount_rcu(nd, &path, &inode, &seq)))
- return -ECHILD;
- } else {
- dget(path.dentry);
- err = follow_managed(&path, nd);
- if (unlikely(err < 0))
- return err;
- inode = d_backing_inode(path.dentry);
- seq = 0;
- }
- path_to_nameidata(&path, nd);
- nd->inode = inode;
- nd->seq = seq;
- return 0;
+ if (!(nd->flags & LOOKUP_RCU))
+ dget(nd->path.dentry);
+ return PTR_ERR(step_into(nd, WALK_NOFOLLOW,
+ nd->path.dentry, nd->inode, nd->seq));
}
/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
@@ -2432,16 +2315,19 @@ static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path
s = ERR_PTR(err);
}
- while (!(err = link_path_walk(s, nd))
- && ((err = lookup_last(nd)) > 0)) {
- s = trailing_symlink(nd);
- }
+ while (!(err = link_path_walk(s, nd)) &&
+ (s = lookup_last(nd)) != NULL)
+ ;
if (!err)
err = complete_walk(nd);
if (!err && nd->flags & LOOKUP_DIRECTORY)
if (!d_can_lookup(nd->path.dentry))
err = -ENOTDIR;
+ if (!err && unlikely(nd->flags & LOOKUP_MOUNTPOINT)) {
+ err = handle_lookup_down(nd);
+ nd->flags &= ~LOOKUP_JUMPED; // no d_weak_revalidate(), please...
+ }
if (!err) {
*path = nd->path;
nd->path.mnt = NULL;
@@ -2470,7 +2356,8 @@ int filename_lookup(int dfd, struct filename *name, unsigned flags,
retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path);
if (likely(!retval))
- audit_inode(name, path->dentry, 0);
+ audit_inode(name, path->dentry,
+ flags & LOOKUP_MOUNTPOINT ? AUDIT_INODE_NOEVAL : 0);
restore_nameidata();
putname(name);
return retval;
@@ -2718,24 +2605,23 @@ int path_pts(struct path *path)
/* Find something mounted on "pts" in the same directory as
* the input path.
*/
- struct dentry *child, *parent;
- struct qstr this;
- int ret;
-
- ret = path_parent_directory(path);
- if (ret)
- return ret;
+ struct dentry *parent = dget_parent(path->dentry);
+ struct dentry *child;
+ struct qstr this = QSTR_INIT("pts", 3);
- parent = path->dentry;
- this.name = "pts";
- this.len = 3;
+ if (unlikely(!path_connected(path->mnt, parent))) {
+ dput(parent);
+ return -ENOENT;
+ }
+ dput(path->dentry);
+ path->dentry = parent;
child = d_hash_and_lookup(parent, &this);
if (!child)
return -ENOENT;
path->dentry = child;
dput(parent);
- follow_mount(path);
+ follow_down(path);
return 0;
}
#endif
@@ -2748,88 +2634,6 @@ int user_path_at_empty(int dfd, const char __user *name, unsigned flags,
}
EXPORT_SYMBOL(user_path_at_empty);
-/**
- * path_mountpoint - look up a path to be umounted
- * @nd: lookup context
- * @flags: lookup flags
- * @path: pointer to container for result
- *
- * Look up the given name, but don't attempt to revalidate the last component.
- * Returns 0 and "path" will be valid on success; Returns error otherwise.
- */
-static int
-path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path)
-{
- const char *s = path_init(nd, flags);
- int err;
-
- while (!(err = link_path_walk(s, nd)) &&
- (err = lookup_last(nd)) > 0) {
- s = trailing_symlink(nd);
- }
- if (!err && (nd->flags & LOOKUP_RCU))
- err = unlazy_walk(nd);
- if (!err)
- err = handle_lookup_down(nd);
- if (!err) {
- *path = nd->path;
- nd->path.mnt = NULL;
- nd->path.dentry = NULL;
- }
- terminate_walk(nd);
- return err;
-}
-
-static int
-filename_mountpoint(int dfd, struct filename *name, struct path *path,
- unsigned int flags)
-{
- struct nameidata nd;
- int error;
- if (IS_ERR(name))
- return PTR_ERR(name);
- set_nameidata(&nd, dfd, name);
- error = path_mountpoint(&nd, flags | LOOKUP_RCU, path);
- if (unlikely(error == -ECHILD))
- error = path_mountpoint(&nd, flags, path);
- if (unlikely(error == -ESTALE))
- error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path);
- if (likely(!error))
- audit_inode(name, path->dentry, AUDIT_INODE_NOEVAL);
- restore_nameidata();
- putname(name);
- return error;
-}
-
-/**
- * user_path_mountpoint_at - lookup a path from userland in order to umount it
- * @dfd: directory file descriptor
- * @name: pathname from userland
- * @flags: lookup flags
- * @path: pointer to container to hold result
- *
- * A umount is a special case for path walking. We're not actually interested
- * in the inode in this situation, and ESTALE errors can be a problem. We
- * simply want track down the dentry and vfsmount attached at the mountpoint
- * and avoid revalidating the last component.
- *
- * Returns 0 and populates "path" on success.
- */
-int
-user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags,
- struct path *path)
-{
- return filename_mountpoint(dfd, getname(name), path, flags);
-}
-
-int
-kern_path_mountpoint(int dfd, const char *name, struct path *path,
- unsigned int flags)
-{
- return filename_mountpoint(dfd, getname_kernel(name), path, flags);
-}
-EXPORT_SYMBOL(kern_path_mountpoint);
-
int __check_sticky(struct inode *dir, struct inode *inode)
{
kuid_t fsuid = current_fsuid();
@@ -3127,18 +2931,14 @@ static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t m
*
* Returns an error code otherwise.
*/
-static int atomic_open(struct nameidata *nd, struct dentry *dentry,
- struct path *path, struct file *file,
- const struct open_flags *op,
- int open_flag, umode_t mode)
+static struct dentry *atomic_open(struct nameidata *nd, struct dentry *dentry,
+ struct file *file,
+ int open_flag, umode_t mode)
{
struct dentry *const DENTRY_NOT_SET = (void *) -1UL;
struct inode *dir = nd->path.dentry->d_inode;
int error;
- if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */
- open_flag &= ~O_TRUNC;
-
if (nd->flags & LOOKUP_DIRECTORY)
open_flag |= O_DIRECTORY;
@@ -3149,19 +2949,10 @@ static int atomic_open(struct nameidata *nd, struct dentry *dentry,
d_lookup_done(dentry);
if (!error) {
if (file->f_mode & FMODE_OPENED) {
- /*
- * We didn't have the inode before the open, so check open
- * permission here.
- */
- int acc_mode = op->acc_mode;
- if (file->f_mode & FMODE_CREATED) {
- WARN_ON(!(open_flag & O_CREAT));
- fsnotify_create(dir, dentry);
- acc_mode = 0;
+ if (unlikely(dentry != file->f_path.dentry)) {
+ dput(dentry);
+ dentry = dget(file->f_path.dentry);
}
- error = may_open(&file->f_path, acc_mode, open_flag);
- if (WARN_ON(error > 0))
- error = -EINVAL;
} else if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) {
error = -EIO;
} else {
@@ -3169,19 +2960,15 @@ static int atomic_open(struct nameidata *nd, struct dentry *dentry,
dput(dentry);
dentry = file->f_path.dentry;
}
- if (file->f_mode & FMODE_CREATED)
- fsnotify_create(dir, dentry);
- if (unlikely(d_is_negative(dentry))) {
+ if (unlikely(d_is_negative(dentry)))
error = -ENOENT;
- } else {
- path->dentry = dentry;
- path->mnt = nd->path.mnt;
- return 0;
- }
}
}
- dput(dentry);
- return error;
+ if (error) {
+ dput(dentry);
+ dentry = ERR_PTR(error);
+ }
+ return dentry;
}
/*
@@ -3199,10 +2986,9 @@ static int atomic_open(struct nameidata *nd, struct dentry *dentry,
*
* An error code is returned on failure.
*/
-static int lookup_open(struct nameidata *nd, struct path *path,
- struct file *file,
- const struct open_flags *op,
- bool got_write)
+static struct dentry *lookup_open(struct nameidata *nd, struct file *file,
+ const struct open_flags *op,
+ bool got_write)
{
struct dentry *dir = nd->path.dentry;
struct inode *dir_inode = dir->d_inode;
@@ -3213,7 +2999,7 @@ static int lookup_open(struct nameidata *nd, struct path *path,
DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
if (unlikely(IS_DEADDIR(dir_inode)))
- return -ENOENT;
+ return ERR_PTR(-ENOENT);
file->f_mode &= ~FMODE_CREATED;
dentry = d_lookup(dir, &nd->last);
@@ -3221,7 +3007,7 @@ static int lookup_open(struct nameidata *nd, struct path *path,
if (!dentry) {
dentry = d_alloc_parallel(dir, &nd->last, &wq);
if (IS_ERR(dentry))
- return PTR_ERR(dentry);
+ return dentry;
}
if (d_in_lookup(dentry))
break;
@@ -3237,7 +3023,7 @@ static int lookup_open(struct nameidata *nd, struct path *path,
}
if (dentry->d_inode) {
/* Cached positive dentry: will open in f_op->open */
- goto out_no_open;
+ return dentry;
}
/*
@@ -3249,41 +3035,27 @@ static int lookup_open(struct nameidata *nd, struct path *path,
* Another problem is returing the "right" error value (e.g. for an
* O_EXCL open we want to return EEXIST not EROFS).
*/
+ if (unlikely(!got_write))
+ open_flag &= ~O_TRUNC;
if (open_flag & O_CREAT) {
+ if (open_flag & O_EXCL)
+ open_flag &= ~O_TRUNC;
if (!IS_POSIXACL(dir->d_inode))
mode &= ~current_umask();
- if (unlikely(!got_write)) {
- create_error = -EROFS;
- open_flag &= ~O_CREAT;
- if (open_flag & (O_EXCL | O_TRUNC))
- goto no_open;
- /* No side effects, safe to clear O_CREAT */
- } else {
+ if (likely(got_write))
create_error = may_o_create(&nd->path, dentry, mode);
- if (create_error) {
- open_flag &= ~O_CREAT;
- if (open_flag & O_EXCL)
- goto no_open;
- }
- }
- } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) &&
- unlikely(!got_write)) {
- /*
- * No O_CREATE -> atomicity not a requirement -> fall
- * back to lookup + open
- */
- goto no_open;
+ else
+ create_error = -EROFS;
}
-
+ if (create_error)
+ open_flag &= ~O_CREAT;
if (dir_inode->i_op->atomic_open) {
- error = atomic_open(nd, dentry, path, file, op, open_flag,
- mode);
- if (unlikely(error == -ENOENT) && create_error)
- error = create_error;
- return error;
+ dentry = atomic_open(nd, dentry, file, open_flag, mode);
+ if (unlikely(create_error) && dentry == ERR_PTR(-ENOENT))
+ dentry = ERR_PTR(create_error);
+ return dentry;
}
-no_open:
if (d_in_lookup(dentry)) {
struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry,
nd->flags);
@@ -3310,78 +3082,60 @@ no_open:
open_flag & O_EXCL);
if (error)
goto out_dput;
- fsnotify_create(dir_inode, dentry);
}
if (unlikely(create_error) && !dentry->d_inode) {
error = create_error;
goto out_dput;
}
-out_no_open:
- path->dentry = dentry;
- path->mnt = nd->path.mnt;
- return 0;
+ return dentry;
out_dput:
dput(dentry);
- return error;
+ return ERR_PTR(error);
}
-/*
- * Handle the last step of open()
- */
-static int do_last(struct nameidata *nd,
+static const char *open_last_lookups(struct nameidata *nd,
struct file *file, const struct open_flags *op)
{
struct dentry *dir = nd->path.dentry;
- kuid_t dir_uid = nd->inode->i_uid;
- umode_t dir_mode = nd->inode->i_mode;
int open_flag = op->open_flag;
- bool will_truncate = (open_flag & O_TRUNC) != 0;
bool got_write = false;
- int acc_mode = op->acc_mode;
unsigned seq;
struct inode *inode;
- struct path path;
+ struct dentry *dentry;
+ const char *res;
int error;
- nd->flags &= ~LOOKUP_PARENT;
nd->flags |= op->intent;
if (nd->last_type != LAST_NORM) {
- error = handle_dots(nd, nd->last_type);
- if (unlikely(error))
- return error;
- goto finish_open;
+ if (nd->depth)
+ put_link(nd);
+ return handle_dots(nd, nd->last_type);
}
if (!(open_flag & O_CREAT)) {
if (nd->last.name[nd->last.len])
nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
/* we _can_ be in RCU mode here */
- error = lookup_fast(nd, &path, &inode, &seq);
- if (likely(error > 0))
+ dentry = lookup_fast(nd, &inode, &seq);
+ if (IS_ERR(dentry))
+ return ERR_CAST(dentry);
+ if (likely(dentry))
goto finish_lookup;
- if (error < 0)
- return error;
-
- BUG_ON(nd->inode != dir->d_inode);
BUG_ON(nd->flags & LOOKUP_RCU);
} else {
/* create side of things */
- /*
- * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED
- * has been cleared when we got to the last component we are
- * about to look up
- */
- error = complete_walk(nd);
- if (error)
- return error;
-
+ if (nd->flags & LOOKUP_RCU) {
+ error = unlazy_walk(nd);
+ if (unlikely(error))
+ return ERR_PTR(error);
+ }
audit_inode(nd->name, dir, AUDIT_INODE_PARENT);
/* trailing slashes? */
if (unlikely(nd->last.name[nd->last.len]))
- return -EISDIR;
+ return ERR_PTR(-EISDIR);
}
if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) {
@@ -3398,108 +3152,90 @@ static int do_last(struct nameidata *nd,
inode_lock(dir->d_inode);
else
inode_lock_shared(dir->d_inode);
- error = lookup_open(nd, &path, file, op, got_write);
+ dentry = lookup_open(nd, file, op, got_write);
+ if (!IS_ERR(dentry) && (file->f_mode & FMODE_CREATED))
+ fsnotify_create(dir->d_inode, dentry);
if (open_flag & O_CREAT)
inode_unlock(dir->d_inode);
else
inode_unlock_shared(dir->d_inode);
- if (error)
- goto out;
-
- if (file->f_mode & FMODE_OPENED) {
- if ((file->f_mode & FMODE_CREATED) ||
- !S_ISREG(file_inode(file)->i_mode))
- will_truncate = false;
-
- audit_inode(nd->name, file->f_path.dentry, 0);
- goto opened;
- }
+ if (got_write)
+ mnt_drop_write(nd->path.mnt);
- if (file->f_mode & FMODE_CREATED) {
- /* Don't check for write permission, don't truncate */
- open_flag &= ~O_TRUNC;
- will_truncate = false;
- acc_mode = 0;
- path_to_nameidata(&path, nd);
- goto finish_open_created;
- }
+ if (IS_ERR(dentry))
+ return ERR_CAST(dentry);
- /*
- * If atomic_open() acquired write access it is dropped now due to
- * possible mount and symlink following (this might be optimized away if
- * necessary...)
- */
- if (got_write) {
- mnt_drop_write(nd->path.mnt);
- got_write = false;
+ if (file->f_mode & (FMODE_OPENED | FMODE_CREATED)) {
+ dput(nd->path.dentry);
+ nd->path.dentry = dentry;
+ return NULL;
}
- error = follow_managed(&path, nd);
- if (unlikely(error < 0))
- return error;
+finish_lookup:
+ if (nd->depth)
+ put_link(nd);
+ res = step_into(nd, WALK_TRAILING, dentry, inode, seq);
+ if (unlikely(res))
+ nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);
+ return res;
+}
- /*
- * create/update audit record if it already exists.
- */
- audit_inode(nd->name, path.dentry, 0);
+/*
+ * Handle the last step of open()
+ */
+static int do_open(struct nameidata *nd,
+ struct file *file, const struct open_flags *op)
+{
+ int open_flag = op->open_flag;
+ bool do_truncate;
+ int acc_mode;
+ int error;
- if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) {
- path_to_nameidata(&path, nd);
- return -EEXIST;
+ if (!(file->f_mode & (FMODE_OPENED | FMODE_CREATED))) {
+ error = complete_walk(nd);
+ if (error)
+ return error;
}
-
- seq = 0; /* out of RCU mode, so the value doesn't matter */
- inode = d_backing_inode(path.dentry);
-finish_lookup:
- error = step_into(nd, &path, 0, inode, seq);
- if (unlikely(error))
- return error;
-finish_open:
- /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */
- error = complete_walk(nd);
- if (error)
- return error;
- audit_inode(nd->name, nd->path.dentry, 0);
+ if (!(file->f_mode & FMODE_CREATED))
+ audit_inode(nd->name, nd->path.dentry, 0);
if (open_flag & O_CREAT) {
- error = -EISDIR;
+ if ((open_flag & O_EXCL) && !(file->f_mode & FMODE_CREATED))
+ return -EEXIST;
if (d_is_dir(nd->path.dentry))
- goto out;
- error = may_create_in_sticky(dir_mode, dir_uid,
+ return -EISDIR;
+ error = may_create_in_sticky(nd->dir_mode, nd->dir_uid,
d_backing_inode(nd->path.dentry));
if (unlikely(error))
- goto out;
+ return error;
}
- error = -ENOTDIR;
if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry))
- goto out;
- if (!d_is_reg(nd->path.dentry))
- will_truncate = false;
+ return -ENOTDIR;
- if (will_truncate) {
+ do_truncate = false;
+ acc_mode = op->acc_mode;
+ if (file->f_mode & FMODE_CREATED) {
+ /* Don't check for write permission, don't truncate */
+ open_flag &= ~O_TRUNC;
+ acc_mode = 0;
+ } else if (d_is_reg(nd->path.dentry) && open_flag & O_TRUNC) {
error = mnt_want_write(nd->path.mnt);
if (error)
- goto out;
- got_write = true;
+ return error;
+ do_truncate = true;
}
-finish_open_created:
error = may_open(&nd->path, acc_mode, open_flag);
- if (error)
- goto out;
- BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */
- error = vfs_open(&nd->path, file);
- if (error)
- goto out;
-opened:
- error = ima_file_check(file, op->acc_mode);
- if (!error && will_truncate)
+ if (!error && !(file->f_mode & FMODE_OPENED))
+ error = vfs_open(&nd->path, file);
+ if (!error)
+ error = ima_file_check(file, op->acc_mode);
+ if (!error && do_truncate)
error = handle_truncate(file);
-out:
if (unlikely(error > 0)) {
WARN_ON(1);
error = -EINVAL;
}
- if (got_write)
+ if (do_truncate)
mnt_drop_write(nd->path.mnt);
return error;
}
@@ -3604,10 +3340,10 @@ static struct file *path_openat(struct nameidata *nd,
} else {
const char *s = path_init(nd, flags);
while (!(error = link_path_walk(s, nd)) &&
- (error = do_last(nd, file, op)) > 0) {
- nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);
- s = trailing_symlink(nd);
- }
+ (s = open_last_lookups(nd, file, op)) != NULL)
+ ;
+ if (!error)
+ error = do_open(nd, file, op);
terminate_walk(nd);
}
if (likely(!error)) {
diff --git a/fs/namespace.c b/fs/namespace.c
index 85b5f7bea82e..a28e4db075ed 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1669,7 +1669,7 @@ int ksys_umount(char __user *name, int flags)
struct path path;
struct mount *mnt;
int retval;
- int lookup_flags = 0;
+ int lookup_flags = LOOKUP_MOUNTPOINT;
if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW))
return -EINVAL;
@@ -1680,7 +1680,7 @@ int ksys_umount(char __user *name, int flags)
if (!(flags & UMOUNT_NOFOLLOW))
lookup_flags |= LOOKUP_FOLLOW;
- retval = user_path_mountpoint_at(AT_FDCWD, name, lookup_flags, &path);
+ retval = user_path_at(AT_FDCWD, name, lookup_flags, &path);
if (retval)
goto out;
mnt = real_mount(path.mnt);
@@ -2697,45 +2697,32 @@ static int do_move_mount_old(struct path *path, const char *old_name)
/*
* add a mount into a namespace's mount tree
*/
-static int do_add_mount(struct mount *newmnt, struct path *path, int mnt_flags)
+static int do_add_mount(struct mount *newmnt, struct mountpoint *mp,
+ struct path *path, int mnt_flags)
{
- struct mountpoint *mp;
- struct mount *parent;
- int err;
+ struct mount *parent = real_mount(path->mnt);
mnt_flags &= ~MNT_INTERNAL_FLAGS;
- mp = lock_mount(path);
- if (IS_ERR(mp))
- return PTR_ERR(mp);
-
- parent = real_mount(path->mnt);
- err = -EINVAL;
if (unlikely(!check_mnt(parent))) {
/* that's acceptable only for automounts done in private ns */
if (!(mnt_flags & MNT_SHRINKABLE))
- goto unlock;
+ return -EINVAL;
/* ... and for those we'd better have mountpoint still alive */
if (!parent->mnt_ns)
- goto unlock;
+ return -EINVAL;
}
/* Refuse the same filesystem on the same mount point */
- err = -EBUSY;
if (path->mnt->mnt_sb == newmnt->mnt.mnt_sb &&
path->mnt->mnt_root == path->dentry)
- goto unlock;
+ return -EBUSY;
- err = -EINVAL;
if (d_is_symlink(newmnt->mnt.mnt_root))
- goto unlock;
+ return -EINVAL;
newmnt->mnt.mnt_flags = mnt_flags;
- err = graft_tree(newmnt, parent, mp);
-
-unlock:
- unlock_mount(mp);
- return err;
+ return graft_tree(newmnt, parent, mp);
}
static bool mount_too_revealing(const struct super_block *sb, int *new_mnt_flags);
@@ -2748,6 +2735,7 @@ static int do_new_mount_fc(struct fs_context *fc, struct path *mountpoint,
unsigned int mnt_flags)
{
struct vfsmount *mnt;
+ struct mountpoint *mp;
struct super_block *sb = fc->root->d_sb;
int error;
@@ -2768,7 +2756,13 @@ static int do_new_mount_fc(struct fs_context *fc, struct path *mountpoint,
mnt_warn_timestamp_expiry(mountpoint, mnt);
- error = do_add_mount(real_mount(mnt), mountpoint, mnt_flags);
+ mp = lock_mount(mountpoint);
+ if (IS_ERR(mp)) {
+ mntput(mnt);
+ return PTR_ERR(mp);
+ }
+ error = do_add_mount(real_mount(mnt), mp, mountpoint, mnt_flags);
+ unlock_mount(mp);
if (error < 0)
mntput(mnt);
return error;
@@ -2829,23 +2823,63 @@ static int do_new_mount(struct path *path, const char *fstype, int sb_flags,
int finish_automount(struct vfsmount *m, struct path *path)
{
- struct mount *mnt = real_mount(m);
+ struct dentry *dentry = path->dentry;
+ struct mountpoint *mp;
+ struct mount *mnt;
int err;
+
+ if (!m)
+ return 0;
+ if (IS_ERR(m))
+ return PTR_ERR(m);
+
+ mnt = real_mount(m);
/* 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(mnt) < 2);
if (m->mnt_sb == path->mnt->mnt_sb &&
- m->mnt_root == path->dentry) {
+ m->mnt_root == dentry) {
err = -ELOOP;
- goto fail;
+ goto discard;
}
- err = do_add_mount(mnt, path, path->mnt->mnt_flags | MNT_SHRINKABLE);
- if (!err)
- return 0;
-fail:
+ /*
+ * we don't want to use lock_mount() - in this case finding something
+ * that overmounts our mountpoint to be means "quitely drop what we've
+ * got", not "try to mount it on top".
+ */
+ inode_lock(dentry->d_inode);
+ namespace_lock();
+ if (unlikely(cant_mount(dentry))) {
+ err = -ENOENT;
+ goto discard_locked;
+ }
+ rcu_read_lock();
+ if (unlikely(__lookup_mnt(path->mnt, dentry))) {
+ rcu_read_unlock();
+ err = 0;
+ goto discard_locked;
+ }
+ rcu_read_unlock();
+ mp = get_mountpoint(dentry);
+ if (IS_ERR(mp)) {
+ err = PTR_ERR(mp);
+ goto discard_locked;
+ }
+
+ err = do_add_mount(mnt, mp, path, path->mnt->mnt_flags | MNT_SHRINKABLE);
+ unlock_mount(mp);
+ if (unlikely(err))
+ goto discard;
+ mntput(m);
+ return 0;
+
+discard_locked:
+ namespace_unlock();
+ inode_unlock(dentry->d_inode);
+discard:
/* remove m from any expiration list it may be on */
if (!list_empty(&mnt->mnt_expire)) {
namespace_lock();
diff --git a/fs/open.c b/fs/open.c
index b69d6eed67e6..719b320ede52 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -1046,8 +1046,10 @@ inline int build_open_flags(const struct open_how *how, struct open_flags *op)
if (flags & O_CREAT) {
op->intent |= LOOKUP_CREATE;
- if (flags & O_EXCL)
+ if (flags & O_EXCL) {
op->intent |= LOOKUP_EXCL;
+ flags |= O_NOFOLLOW;
+ }
}
if (flags & O_DIRECTORY)
diff --git a/include/linux/namei.h b/include/linux/namei.h
index 0dd980d7318f..a4bb992623c4 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -15,7 +15,7 @@ enum { MAX_NESTED_LINKS = 8 };
/*
* Type of the last component on LOOKUP_PARENT
*/
-enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND};
+enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT};
/* pathwalk mode */
#define LOOKUP_FOLLOW 0x0001 /* follow links at the end */
@@ -23,6 +23,7 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND};
#define LOOKUP_AUTOMOUNT 0x0004 /* force terminal automount */
#define LOOKUP_EMPTY 0x4000 /* accept empty path [user_... only] */
#define LOOKUP_DOWN 0x8000 /* follow mounts in the starting point */
+#define LOOKUP_MOUNTPOINT 0x0080 /* follow mounts in the end */
#define LOOKUP_REVAL 0x0020 /* tell ->d_revalidate() to trust no cache */
#define LOOKUP_RCU 0x0040 /* RCU pathwalk mode; semi-internal */
@@ -64,7 +65,6 @@ extern struct dentry *kern_path_create(int, const char *, struct path *, unsigne
extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int);
extern void done_path_create(struct path *, struct dentry *);
extern struct dentry *kern_path_locked(const char *, struct path *);
-extern int kern_path_mountpoint(int, const char *, struct path *, unsigned int);
extern struct dentry *try_lookup_one_len(const char *, struct dentry *, int);
extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-10 23:50:17 +0000