/**
* unlazy_walk - try to switch to ref-walk mode.
* @nd: nameidata pathwalk data
- * @dentry: child of nd->path.dentry or NULL
- * @seq: seq number to check dentry against
* Returns: 0 on success, -ECHILD on failure
*
- * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry
- * for ref-walk mode. @dentry must be a path found by a do_lookup call on
- * @nd or NULL. Must be called from rcu-walk context.
+ * unlazy_walk attempts to legitimize the current nd->path and nd->root
+ * for ref-walk mode.
+ * Must be called from rcu-walk context.
* Nothing should touch nameidata between unlazy_walk() failure and
* terminate_walk().
*/
-static int unlazy_walk(struct nameidata *nd, struct dentry *dentry, unsigned seq)
+static int unlazy_walk(struct nameidata *nd)
{
struct dentry *parent = nd->path.dentry;
BUG_ON(!(nd->flags & LOOKUP_RCU));
+ nd->flags &= ~LOOKUP_RCU;
+ if (unlikely(!legitimize_links(nd)))
+ goto out2;
+ if (unlikely(!legitimize_path(nd, &nd->path, nd->seq)))
+ goto out1;
+ if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
+ if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq)))
+ goto out;
+ }
+ rcu_read_unlock();
+ BUG_ON(nd->inode != parent->d_inode);
+ return 0;
+
+out2:
+ nd->path.mnt = NULL;
+ nd->path.dentry = NULL;
+out1:
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
+out:
+ rcu_read_unlock();
+ return -ECHILD;
+}
+
+/**
+ * unlazy_child - try to switch to ref-walk mode.
+ * @nd: nameidata pathwalk data
+ * @dentry: child of nd->path.dentry
+ * @seq: seq number to check dentry against
+ * Returns: 0 on success, -ECHILD on failure
+ *
+ * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry
+ * for ref-walk mode. @dentry must be a path found by a do_lookup call on
+ * @nd. Must be called from rcu-walk context.
+ * Nothing should touch nameidata between unlazy_child() failure and
+ * terminate_walk().
+ */
+static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq)
+{
+ BUG_ON(!(nd->flags & LOOKUP_RCU));
+
nd->flags &= ~LOOKUP_RCU;
if (unlikely(!legitimize_links(nd)))
goto out2;
if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq)))
goto out2;
- if (unlikely(!lockref_get_not_dead(&parent->d_lockref)))
+ if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref)))
goto out1;
/*
- * For a negative lookup, the lookup sequence point is the parents
- * sequence point, and it only needs to revalidate the parent dentry.
- *
- * For a positive lookup, we need to move both the parent and the
- * dentry from the RCU domain to be properly refcounted. And the
- * sequence number in the dentry validates *both* dentry counters,
- * since we checked the sequence number of the parent after we got
- * the child sequence number. So we know the parent must still
- * be valid if the child sequence number is still valid.
+ * We need to move both the parent and the dentry from the RCU domain
+ * to be properly refcounted. And the sequence number in the dentry
+ * validates *both* dentry counters, since we checked the sequence
+ * number of the parent after we got the child sequence number. So we
+ * know the parent must still be valid if the child sequence number is
*/
- if (!dentry) {
- if (read_seqcount_retry(&parent->d_seq, nd->seq))
- goto out;
- BUG_ON(nd->inode != parent->d_inode);
- } else {
- if (!lockref_get_not_dead(&dentry->d_lockref))
- goto out;
- if (read_seqcount_retry(&dentry->d_seq, seq))
- goto drop_dentry;
+ if (unlikely(!lockref_get_not_dead(&dentry->d_lockref)))
+ goto out;
+ if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) {
+ rcu_read_unlock();
+ dput(dentry);
+ goto drop_root_mnt;
}
-
/*
* Sequence counts matched. Now make sure that the root is
* still valid and get it if required.
rcu_read_unlock();
return 0;
-drop_dentry:
- rcu_read_unlock();
- dput(dentry);
- goto drop_root_mnt;
out2:
nd->path.mnt = NULL;
out1:
return -ECHILD;
}
-static int unlazy_link(struct nameidata *nd, struct path *link, unsigned seq)
-{
- 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;
- if (!(nd->flags & LOOKUP_ROOT))
- nd->root.mnt = NULL;
- rcu_read_unlock();
- } else if (likely(unlazy_walk(nd, NULL, 0)) == 0) {
- return 0;
- }
- path_put(link);
- return -ECHILD;
-}
-
static inline int d_revalidate(struct dentry *dentry, unsigned int flags)
{
- return dentry->d_op->d_revalidate(dentry, flags);
+ if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE))
+ return dentry->d_op->d_revalidate(dentry, flags);
+ else
+ return 1;
}
/**
if (nd->flags & LOOKUP_RCU) {
if (!(nd->flags & LOOKUP_ROOT))
nd->root.mnt = NULL;
- if (unlikely(unlazy_walk(nd, NULL, 0)))
+ if (unlikely(unlazy_walk(nd)))
return -ECHILD;
}
touch_atime(&last->link);
cond_resched();
} else if (atime_needs_update_rcu(&last->link, inode)) {
- if (unlikely(unlazy_walk(nd, NULL, 0)))
+ if (unlikely(unlazy_walk(nd)))
return ERR_PTR(-ECHILD);
touch_atime(&last->link);
}
if (nd->flags & LOOKUP_RCU) {
res = get(NULL, inode, &last->done);
if (res == ERR_PTR(-ECHILD)) {
- if (unlikely(unlazy_walk(nd, NULL, 0)))
+ if (unlikely(unlazy_walk(nd)))
return ERR_PTR(-ECHILD);
res = get(dentry, inode, &last->done);
}
bool *need_mntput)
{
struct vfsmount *mnt;
- const struct cred *old_cred;
int err;
if (!path->dentry->d_op || !path->dentry->d_op->d_automount)
if (nd->total_link_count >= 40)
return -ELOOP;
- old_cred = override_creds(&init_cred);
mnt = path->dentry->d_op->d_automount(path);
- revert_creds(old_cred);
if (IS_ERR(mnt)) {
/*
* The filesystem is allowed to return -EISDIR here to indicate
struct dentry *dir,
unsigned int flags)
{
- struct dentry *dentry;
- int error;
-
- dentry = d_lookup(dir, name);
+ struct dentry *dentry = d_lookup(dir, name);
if (dentry) {
- if (dentry->d_flags & DCACHE_OP_REVALIDATE) {
- error = d_revalidate(dentry, flags);
- if (unlikely(error <= 0)) {
- if (!error)
- d_invalidate(dentry);
- dput(dentry);
- return ERR_PTR(error);
- }
+ int error = d_revalidate(dentry, flags);
+ if (unlikely(error <= 0)) {
+ if (!error)
+ d_invalidate(dentry);
+ dput(dentry);
+ return ERR_PTR(error);
}
}
return dentry;
bool negative;
dentry = __d_lookup_rcu(parent, &nd->last, &seq);
if (unlikely(!dentry)) {
- if (unlazy_walk(nd, NULL, 0))
+ if (unlazy_walk(nd))
return -ECHILD;
return 0;
}
return -ECHILD;
*seqp = seq;
- if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE))
- status = d_revalidate(dentry, nd->flags);
- if (unlikely(status <= 0)) {
- if (unlazy_walk(nd, dentry, seq))
- return -ECHILD;
- if (status == -ECHILD)
- status = d_revalidate(dentry, nd->flags);
- } else {
+ status = d_revalidate(dentry, nd->flags);
+ if (likely(status > 0)) {
/*
* Note: do negative dentry check after revalidation in
* case that drops it.
path->dentry = dentry;
if (likely(__follow_mount_rcu(nd, path, inode, seqp)))
return 1;
- if (unlazy_walk(nd, dentry, seq))
- return -ECHILD;
}
+ if (unlazy_child(nd, dentry, seq))
+ return -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;
- if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE))
- status = d_revalidate(dentry, nd->flags);
+ status = d_revalidate(dentry, nd->flags);
}
if (unlikely(status <= 0)) {
if (!status)
if (IS_ERR(dentry))
goto out;
if (unlikely(!d_in_lookup(dentry))) {
- if ((dentry->d_flags & DCACHE_OP_REVALIDATE) &&
- !(flags & LOOKUP_NO_REVAL)) {
+ if (!(flags & LOOKUP_NO_REVAL)) {
int error = d_revalidate(dentry, flags);
if (unlikely(error <= 0)) {
if (!error) {
int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK);
if (err != -ECHILD)
return err;
- if (unlazy_walk(nd, NULL, 0))
+ if (unlazy_walk(nd))
return -ECHILD;
}
return inode_permission(nd->inode, MAY_EXEC);
error = nd_alloc_stack(nd);
if (unlikely(error)) {
if (error == -ECHILD) {
- if (unlikely(unlazy_link(nd, link, seq)))
- return -ECHILD;
- error = nd_alloc_stack(nd);
+ 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;
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
+ rcu_read_unlock();
+ } else if (likely(unlazy_walk(nd)) == 0)
+ error = nd_alloc_stack(nd);
}
if (error) {
path_put(link);
}
if (unlikely(!d_can_lookup(nd->path.dentry))) {
if (nd->flags & LOOKUP_RCU) {
- if (unlazy_walk(nd, NULL, 0))
+ if (unlazy_walk(nd))
return -ECHILD;
}
return -ENOTDIR;
/* If we're in rcuwalk, drop out of it to handle last component */
if (nd->flags & LOOKUP_RCU) {
- if (unlazy_walk(nd, NULL, 0))
+ if (unlazy_walk(nd))
return -ECHILD;
}
static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode)
{
+ struct user_namespace *s_user_ns;
int error = security_path_mknod(dir, dentry, mode, 0);
if (error)
return error;
+ s_user_ns = dir->dentry->d_sb->s_user_ns;
+ if (!kuid_has_mapping(s_user_ns, current_fsuid()) ||
+ !kgid_has_mapping(s_user_ns, current_fsgid()))
+ return -EOVERFLOW;
+
error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC);
if (error)
return error;
if (d_in_lookup(dentry))
break;
- if (!(dentry->d_flags & DCACHE_OP_REVALIDATE))
- break;
-
error = d_revalidate(dentry, nd->flags);
if (likely(error > 0))
break;
projects / mirror_ubuntu-bionic-kernel.git / blobdiff