current->nameidata = old;
if (old)
old->total_link_count = now->total_link_count;
- if (now->stack != now->internal) {
+ if (now->stack != now->internal)
kfree(now->stack);
- now->stack = now->internal;
- }
}
static int __nd_alloc_stack(struct nameidata *nd)
* Path walking has 2 modes, rcu-walk and ref-walk (see
* Documentation/filesystems/path-lookup.txt). In situations when we can't
* continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
- * normal reference counts on dentries and vfsmounts to transition to rcu-walk
+ * normal reference counts on dentries and vfsmounts to transition to ref-walk
* mode. Refcounts are grabbed at the last known good point before rcu-walk
* got stuck, so ref-walk may continue from there. If this is not successful
* (eg. a seqcount has changed), then failure is returned and it's up to caller
}
static void set_root(struct nameidata *nd)
-{
- get_fs_root(current->fs, &nd->root);
-}
-
-static void set_root_rcu(struct nameidata *nd)
{
struct fs_struct *fs = current->fs;
- unsigned seq;
- do {
- seq = read_seqcount_begin(&fs->seq);
- nd->root = fs->root;
- nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq);
- } while (read_seqcount_retry(&fs->seq, seq));
+ if (nd->flags & LOOKUP_RCU) {
+ unsigned seq;
+
+ do {
+ seq = read_seqcount_begin(&fs->seq);
+ nd->root = fs->root;
+ nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq);
+ } while (read_seqcount_retry(&fs->seq, seq));
+ } else {
+ get_fs_root(fs, &nd->root);
+ }
}
static void path_put_conditional(struct path *path, struct nameidata *nd)
nd->path.dentry = path->dentry;
}
+static int nd_jump_root(struct nameidata *nd)
+{
+ if (nd->flags & LOOKUP_RCU) {
+ struct dentry *d;
+ 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 -ECHILD;
+ } else {
+ path_put(&nd->path);
+ nd->path = nd->root;
+ path_get(&nd->path);
+ nd->inode = nd->path.dentry->d_inode;
+ }
+ nd->flags |= LOOKUP_JUMPED;
+ return 0;
+}
+
/*
* Helper to directly jump to a known parsed path from ->get_link,
* caller must have taken a reference to path beforehand.
return res;
}
if (*res == '/') {
- 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;
+ if (!nd->root.mnt)
+ set_root(nd);
+ if (unlikely(nd_jump_root(nd)))
+ return ERR_PTR(-ECHILD);
while (unlikely(*++res == '/'))
;
}
static int follow_dotdot_rcu(struct nameidata *nd)
{
struct inode *inode = nd->inode;
- if (!nd->root.mnt)
- set_root_rcu(nd);
while (1) {
if (path_equal(&nd->path, &nd->root))
static int follow_dotdot(struct nameidata *nd)
{
- if (!nd->root.mnt)
- set_root(nd);
-
while(1) {
struct dentry *old = nd->path.dentry;
static inline int handle_dots(struct nameidata *nd, int type)
{
if (type == LAST_DOTDOT) {
+ if (!nd->root.mnt)
+ set_root(nd);
if (nd->flags & LOOKUP_RCU) {
return follow_dotdot_rcu(nd);
} else
}
nd->root.mnt = NULL;
+ nd->path.mnt = NULL;
+ nd->path.dentry = NULL;
nd->m_seq = read_seqbegin(&mount_lock);
if (*s == '/') {
- if (flags & LOOKUP_RCU) {
+ if (flags & LOOKUP_RCU)
rcu_read_lock();
- set_root_rcu(nd);
- nd->seq = nd->root_seq;
- } else {
- set_root(nd);
- path_get(&nd->root);
- }
- nd->path = nd->root;
+ set_root(nd);
+ if (likely(!nd_jump_root(nd)))
+ return s;
+ nd->root.mnt = NULL;
+ rcu_read_unlock();
+ return ERR_PTR(-ECHILD);
} else if (nd->dfd == AT_FDCWD) {
if (flags & LOOKUP_RCU) {
struct fs_struct *fs = current->fs;
do {
seq = read_seqcount_begin(&fs->seq);
nd->path = fs->pwd;
+ nd->inode = nd->path.dentry->d_inode;
nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
} while (read_seqcount_retry(&fs->seq, seq));
} else {
get_fs_pwd(current->fs, &nd->path);
+ nd->inode = nd->path.dentry->d_inode;
}
+ return s;
} else {
/* Caller must check execute permissions on the starting path component */
struct fd f = fdget_raw(nd->dfd);
fdput(f);
return s;
}
-
- nd->inode = nd->path.dentry->d_inode;
- if (!(flags & LOOKUP_RCU))
- return s;
- if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq)))
- return s;
- if (!(nd->flags & LOOKUP_ROOT))
- nd->root.mnt = NULL;
- rcu_read_unlock();
- return ERR_PTR(-ECHILD);
}
static const char *trailing_symlink(struct nameidata *nd)
*
* Note that this routine is purely a helper for filesystem usage and should
* not be called by generic code.
+ *
+ * The caller must hold base->i_mutex.
*/
struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
{
}
EXPORT_SYMBOL(lookup_one_len);
+/**
+ * lookup_one_len_unlocked - filesystem helper to lookup single pathname component
+ * @name: pathname component to lookup
+ * @base: base directory to lookup from
+ * @len: maximum length @len should be interpreted to
+ *
+ * Note that this routine is purely a helper for filesystem usage and should
+ * not be called by generic code.
+ *
+ * Unlike lookup_one_len, it should be called without the parent
+ * i_mutex held, and will take the i_mutex itself if necessary.
+ */
+struct dentry *lookup_one_len_unlocked(const char *name,
+ struct dentry *base, int len)
+{
+ struct qstr this;
+ unsigned int c;
+ int err;
+ struct dentry *ret;
+
+ this.name = name;
+ this.len = len;
+ this.hash = full_name_hash(name, len);
+ if (!len)
+ return ERR_PTR(-EACCES);
+
+ if (unlikely(name[0] == '.')) {
+ if (len < 2 || (len == 2 && name[1] == '.'))
+ return ERR_PTR(-EACCES);
+ }
+
+ while (len--) {
+ c = *(const unsigned char *)name++;
+ if (c == '/' || c == '\0')
+ return ERR_PTR(-EACCES);
+ }
+ /*
+ * See if the low-level filesystem might want
+ * to use its own hash..
+ */
+ if (base->d_flags & DCACHE_OP_HASH) {
+ int err = base->d_op->d_hash(base, &this);
+ if (err < 0)
+ return ERR_PTR(err);
+ }
+
+ err = inode_permission(base->d_inode, MAY_EXEC);
+ if (err)
+ return ERR_PTR(err);
+
+ /*
+ * __d_lookup() is used to try to get a quick answer and avoid the
+ * mutex. A false-negative does no harm.
+ */
+ ret = __d_lookup(base, &this);
+ if (ret && unlikely(ret->d_flags & DCACHE_OP_REVALIDATE)) {
+ dput(ret);
+ ret = NULL;
+ }
+ if (ret)
+ return ret;
+
+ mutex_lock(&base->d_inode->i_mutex);
+ ret = __lookup_hash(&this, base, 0);
+ mutex_unlock(&base->d_inode->i_mutex);
+ return ret;
+}
+EXPORT_SYMBOL(lookup_one_len_unlocked);
+
int user_path_at_empty(int dfd, const char __user *name, unsigned flags,
struct path *path, int *empty)
{
struct inode *inode = dentry->d_inode;
int error;
- /* O_PATH? */
- if (!acc_mode)
- return 0;
-
if (!inode)
return -ENOENT;
break;
}
- error = inode_permission(inode, acc_mode);
+ error = inode_permission(inode, MAY_OPEN | acc_mode);
if (error)
return error;
if (*opened & FILE_CREATED) {
WARN_ON(!(open_flag & O_CREAT));
fsnotify_create(dir, dentry);
- acc_mode = MAY_OPEN;
+ acc_mode = 0;
}
error = may_open(&file->f_path, acc_mode, open_flag);
if (error)
/* Don't check for write permission, don't truncate */
open_flag &= ~O_TRUNC;
will_truncate = false;
- acc_mode = MAY_OPEN;
+ acc_mode = 0;
path_to_nameidata(&path, nd);
goto finish_open_created;
}
got_write = true;
}
finish_open_created:
- error = may_open(&nd->path, acc_mode, open_flag);
- if (error)
- goto out;
-
+ if (likely(!(open_flag & O_PATH))) {
+ error = may_open(&nd->path, acc_mode, open_flag);
+ if (error)
+ goto out;
+ }
BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */
error = vfs_open(&nd->path, file, current_cred());
if (!error) {
goto out2;
audit_inode(nd->name, child, 0);
/* Don't check for other permissions, the inode was just created */
- error = may_open(&path, MAY_OPEN, op->open_flag);
+ error = may_open(&path, 0, op->open_flag);
if (error)
goto out2;
file->f_path.mnt = path.mnt;
projects / linux-2.6-microblaze.git / blobdiff