struct path root;
struct inode *inode; /* path.dentry.d_inode */
unsigned int flags;
- unsigned seq, m_seq;
+ unsigned seq, m_seq, root_seq;
int last_type;
unsigned depth;
int total_link_count;
void *cookie;
const char *name;
struct inode *inode;
+ unsigned seq;
} *stack, internal[EMBEDDED_LEVELS];
};
static int __nd_alloc_stack(struct nameidata *nd)
{
- struct saved *p = kmalloc(MAXSYMLINKS * sizeof(struct saved),
+ struct saved *p;
+
+ if (nd->flags & LOOKUP_RCU) {
+ p= kmalloc(MAXSYMLINKS * sizeof(struct saved),
+ GFP_ATOMIC);
+ if (unlikely(!p))
+ return -ECHILD;
+ } else {
+ p= kmalloc(MAXSYMLINKS * sizeof(struct saved),
GFP_KERNEL);
- if (unlikely(!p))
- return -ENOMEM;
+ if (unlikely(!p))
+ return -ENOMEM;
+ }
memcpy(p, nd->internal, sizeof(nd->internal));
nd->stack = p;
return 0;
return __nd_alloc_stack(nd);
}
+static void drop_links(struct nameidata *nd)
+{
+ int i = nd->depth;
+ while (i--) {
+ struct saved *last = nd->stack + i;
+ struct inode *inode = last->inode;
+ if (last->cookie && inode->i_op->put_link) {
+ inode->i_op->put_link(inode, last->cookie);
+ last->cookie = NULL;
+ }
+ }
+}
+
+static void terminate_walk(struct nameidata *nd)
+{
+ drop_links(nd);
+ if (!(nd->flags & LOOKUP_RCU)) {
+ int i;
+ path_put(&nd->path);
+ for (i = 0; i < nd->depth; i++)
+ path_put(&nd->stack[i].link);
+ } else {
+ nd->flags &= ~LOOKUP_RCU;
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
+ rcu_read_unlock();
+ }
+ nd->depth = 0;
+}
+
+/* path_put is needed afterwards regardless of success or failure */
+static bool legitimize_path(struct nameidata *nd,
+ struct path *path, unsigned seq)
+{
+ int res = __legitimize_mnt(path->mnt, nd->m_seq);
+ if (unlikely(res)) {
+ if (res > 0)
+ path->mnt = NULL;
+ path->dentry = NULL;
+ return false;
+ }
+ if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) {
+ path->dentry = NULL;
+ return false;
+ }
+ return !read_seqcount_retry(&path->dentry->d_seq, seq);
+}
+
+static bool legitimize_links(struct nameidata *nd)
+{
+ int i;
+ for (i = 0; i < nd->depth; i++) {
+ struct saved *last = nd->stack + i;
+ if (unlikely(!legitimize_path(nd, &last->link, last->seq))) {
+ drop_links(nd);
+ nd->depth = i + 1;
+ return false;
+ }
+ }
+ return true;
+}
+
/*
* Path walking has 2 modes, rcu-walk and ref-walk (see
* Documentation/filesystems/path-lookup.txt). In situations when we can't
* 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.
+ * Nothing should touch nameidata between unlazy_walk() failure and
+ * terminate_walk().
*/
static int unlazy_walk(struct nameidata *nd, struct dentry *dentry, unsigned seq)
{
- struct fs_struct *fs = current->fs;
struct dentry *parent = nd->path.dentry;
BUG_ON(!(nd->flags & LOOKUP_RCU));
- /*
- * After legitimizing the bastards, terminate_walk()
- * will do the right thing for non-RCU mode, and all our
- * subsequent exit cases should rcu_read_unlock()
- * before returning. Do vfsmount first; if dentry
- * can't be legitimized, just set nd->path.dentry to NULL
- * and rely on dput(NULL) being a no-op.
- */
- if (!legitimize_mnt(nd->path.mnt, nd->m_seq))
- return -ECHILD;
nd->flags &= ~LOOKUP_RCU;
-
- if (!lockref_get_not_dead(&parent->d_lockref)) {
- nd->path.dentry = NULL;
- goto out;
- }
+ 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)))
+ goto out1;
/*
* For a negative lookup, the lookup sequence point is the parents
* still valid and get it if required.
*/
if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
- spin_lock(&fs->lock);
- if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry)
- goto unlock_and_drop_dentry;
- path_get(&nd->root);
- spin_unlock(&fs->lock);
+ if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) {
+ rcu_read_unlock();
+ dput(dentry);
+ return -ECHILD;
+ }
}
rcu_read_unlock();
return 0;
-unlock_and_drop_dentry:
- spin_unlock(&fs->lock);
drop_dentry:
rcu_read_unlock();
dput(dentry);
goto drop_root_mnt;
+out2:
+ nd->path.mnt = NULL;
+out1:
+ nd->path.dentry = NULL;
out:
rcu_read_unlock();
drop_root_mnt:
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);
return status;
}
-static __always_inline void set_root(struct nameidata *nd)
+static void set_root(struct nameidata *nd)
{
get_fs_root(current->fs, &nd->root);
}
-static __always_inline unsigned set_root_rcu(struct nameidata *nd)
+static unsigned set_root_rcu(struct nameidata *nd)
{
struct fs_struct *fs = current->fs;
- unsigned seq, res;
+ unsigned seq;
do {
seq = read_seqcount_begin(&fs->seq);
nd->root = fs->root;
- res = __read_seqcount_begin(&nd->root.dentry->d_seq);
+ nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq);
} while (read_seqcount_retry(&fs->seq, seq));
- return res;
+ return nd->root_seq;
}
static void path_put_conditional(struct path *path, struct nameidata *nd)
struct saved *last = nd->stack + --nd->depth;
struct inode *inode = last->inode;
if (last->cookie && inode->i_op->put_link)
- inode->i_op->put_link(last->link.dentry, last->cookie);
- path_put(&last->link);
+ inode->i_op->put_link(inode, last->cookie);
+ if (!(nd->flags & LOOKUP_RCU))
+ path_put(&last->link);
}
int sysctl_protected_symlinks __read_mostly = 0;
if (uid_eq(parent->i_uid, inode->i_uid))
return 0;
+ if (nd->flags & LOOKUP_RCU)
+ return -ECHILD;
+
audit_log_link_denied("follow_link", &nd->stack[0].link);
return -EACCES;
}
int error;
const char *res;
- BUG_ON(nd->flags & LOOKUP_RCU);
-
- cond_resched();
-
- touch_atime(&last->link);
+ if (!(nd->flags & LOOKUP_RCU)) {
+ touch_atime(&last->link);
+ cond_resched();
+ } else if (atime_needs_update(&last->link, inode)) {
+ if (unlikely(unlazy_walk(nd, NULL, 0)))
+ return ERR_PTR(-ECHILD);
+ touch_atime(&last->link);
+ }
error = security_inode_follow_link(dentry, inode,
nd->flags & LOOKUP_RCU);
nd->last_type = LAST_BIND;
res = inode->i_link;
if (!res) {
+ if (nd->flags & LOOKUP_RCU) {
+ if (unlikely(unlazy_walk(nd, NULL, 0)))
+ return ERR_PTR(-ECHILD);
+ }
res = inode->i_op->follow_link(dentry, &last->cookie);
if (IS_ERR_OR_NULL(res)) {
last->cookie = NULL;
}
}
if (*res == '/') {
- if (!nd->root.mnt)
- set_root(nd);
- path_put(&nd->path);
- nd->path = nd->root;
- path_get(&nd->root);
- nd->inode = nd->path.dentry->d_inode;
+ if (nd->flags & LOOKUP_RCU) {
+ struct dentry *d;
+ if (!nd->root.mnt)
+ set_root_rcu(nd);
+ nd->path = nd->root;
+ d = nd->path.dentry;
+ nd->inode = d->d_inode;
+ nd->seq = nd->root_seq;
+ if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq)))
+ return ERR_PTR(-ECHILD);
+ } else {
+ if (!nd->root.mnt)
+ set_root(nd);
+ path_put(&nd->path);
+ nd->path = nd->root;
+ path_get(&nd->root);
+ nd->inode = nd->path.dentry->d_inode;
+ }
nd->flags |= LOOKUP_JUMPED;
while (unlikely(*++res == '/'))
;
return res;
}
-static int follow_up_rcu(struct path *path)
-{
- struct mount *mnt = real_mount(path->mnt);
- struct mount *parent;
- struct dentry *mountpoint;
-
- parent = mnt->mnt_parent;
- if (&parent->mnt == path->mnt)
- return 0;
- mountpoint = mnt->mnt_mountpoint;
- path->dentry = mountpoint;
- path->mnt = &parent->mnt;
- return 1;
-}
-
/*
* follow_up - Find the mountpoint of path's vfsmount
*
set_root_rcu(nd);
while (1) {
- if (nd->path.dentry == nd->root.dentry &&
- nd->path.mnt == nd->root.mnt) {
+ if (path_equal(&nd->path, &nd->root))
break;
- }
if (nd->path.dentry != nd->path.mnt->mnt_root) {
struct dentry *old = nd->path.dentry;
struct dentry *parent = old->d_parent;
inode = parent->d_inode;
seq = read_seqcount_begin(&parent->d_seq);
- if (read_seqcount_retry(&old->d_seq, nd->seq))
- goto failed;
+ if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq)))
+ return -ECHILD;
nd->path.dentry = parent;
nd->seq = seq;
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;
+ /* we know that mountpoint was pinned */
+ nd->path.dentry = mountpoint;
+ nd->path.mnt = &mparent->mnt;
+ inode = inode2;
+ nd->seq = seq;
}
- if (!follow_up_rcu(&nd->path))
- break;
- inode = nd->path.dentry->d_inode;
- nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
}
- while (d_mountpoint(nd->path.dentry)) {
+ 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;
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);
- if (read_seqretry(&mount_lock, nd->m_seq))
- goto failed;
}
nd->inode = inode;
return 0;
-
-failed:
- return -ECHILD;
}
/*
return 0;
}
-static void terminate_walk(struct nameidata *nd)
-{
- if (!(nd->flags & LOOKUP_RCU)) {
- path_put(&nd->path);
- } else {
- nd->flags &= ~LOOKUP_RCU;
- if (!(nd->flags & LOOKUP_ROOT))
- nd->root.mnt = NULL;
- rcu_read_unlock();
- }
- while (unlikely(nd->depth))
- put_link(nd);
-}
-
static int pick_link(struct nameidata *nd, struct path *link,
struct inode *inode, unsigned seq)
{
path_to_nameidata(link, nd);
return -ELOOP;
}
- if (nd->flags & LOOKUP_RCU) {
- if (unlikely(nd->path.mnt != link->mnt ||
- unlazy_walk(nd, link->dentry, seq))) {
- return -ECHILD;
- }
+ if (!(nd->flags & LOOKUP_RCU)) {
+ if (link->mnt == nd->path.mnt)
+ mntget(link->mnt);
}
- if (link->mnt == nd->path.mnt)
- mntget(link->mnt);
error = nd_alloc_stack(nd);
if (unlikely(error)) {
- path_put(link);
- return error;
+ if (error == -ECHILD) {
+ if (unlikely(unlazy_link(nd, link, seq)))
+ return -ECHILD;
+ error = nd_alloc_stack(nd);
+ }
+ if (error) {
+ path_put(link);
+ return error;
+ }
}
last = nd->stack + nd->depth++;
last->link = *link;
last->cookie = NULL;
last->inode = inode;
+ last->seq = seq;
return 1;
}
if (flags & LOOKUP_RCU) {
rcu_read_lock();
nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
+ nd->root_seq = nd->seq;
nd->m_seq = read_seqbegin(&mount_lock);
} else {
path_get(&nd->path);
int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
{
void *cookie;
- const char *link = dentry->d_inode->i_link;
+ struct inode *inode = d_inode(dentry);
+ const char *link = inode->i_link;
int res;
if (!link) {
- link = dentry->d_inode->i_op->follow_link(dentry, &cookie);
+ link = inode->i_op->follow_link(dentry, &cookie);
if (IS_ERR(link))
return PTR_ERR(link);
}
res = readlink_copy(buffer, buflen, link);
- if (dentry->d_inode->i_op->put_link)
- dentry->d_inode->i_op->put_link(dentry, cookie);
+ if (inode->i_op->put_link)
+ inode->i_op->put_link(inode, cookie);
return res;
}
EXPORT_SYMBOL(generic_readlink);
}
EXPORT_SYMBOL(page_follow_link_light);
-void page_put_link(struct dentry *dentry, void *cookie)
+void page_put_link(struct inode *unused, void *cookie)
{
struct page *page = cookie;
kunmap(page);
projects / karo-tx-linux.git / blobdiff