forked from Minki/linux
pull handling of one pathname component into a helper
new helper: walk_component(). Handles everything except symlinks; returns negative on error, 0 on success and 1 on symlinks we decided to follow. Drops out of RCU mode on such symlinks. link_path_walk() and do_last() switched to using that. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro
parent
11a7b371b6
commit
ce57dfc179
123
fs/namei.c
123
fs/namei.c
@ -785,16 +785,11 @@ __do_follow_link(const struct path *link, struct nameidata *nd, void **p)
|
||||
* Without that kind of total limit, nasty chains of consecutive
|
||||
* symlinks can cause almost arbitrarily long lookups.
|
||||
*/
|
||||
static inline int do_follow_link(struct inode *inode, struct path *path, struct nameidata *nd)
|
||||
static inline int do_follow_link(struct path *path, struct nameidata *nd)
|
||||
{
|
||||
void *cookie;
|
||||
int err = -ELOOP;
|
||||
|
||||
/* We drop rcu-walk here */
|
||||
if (nameidata_dentry_drop_rcu_maybe(nd, path->dentry))
|
||||
return -ECHILD;
|
||||
BUG_ON(inode != path->dentry->d_inode);
|
||||
|
||||
if (current->link_count >= MAX_NESTED_LINKS)
|
||||
goto loop;
|
||||
if (current->total_link_count >= 40)
|
||||
@ -1337,6 +1332,39 @@ static void terminate_walk(struct nameidata *nd)
|
||||
}
|
||||
}
|
||||
|
||||
static inline int walk_component(struct nameidata *nd, struct path *path,
|
||||
struct qstr *name, int type, int follow)
|
||||
{
|
||||
struct inode *inode;
|
||||
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(type != LAST_NORM))
|
||||
return handle_dots(nd, type);
|
||||
err = do_lookup(nd, name, path, &inode);
|
||||
if (unlikely(err)) {
|
||||
terminate_walk(nd);
|
||||
return err;
|
||||
}
|
||||
if (!inode) {
|
||||
path_to_nameidata(path, nd);
|
||||
terminate_walk(nd);
|
||||
return -ENOENT;
|
||||
}
|
||||
if (unlikely(inode->i_op->follow_link) && follow) {
|
||||
if (nameidata_dentry_drop_rcu_maybe(nd, path->dentry))
|
||||
return -ECHILD;
|
||||
BUG_ON(inode != path->dentry->d_inode);
|
||||
return 1;
|
||||
}
|
||||
path_to_nameidata(path, nd);
|
||||
nd->inode = inode;
|
||||
return 0;
|
||||
}
|
||||
|
||||
/*
|
||||
* Name resolution.
|
||||
* This is the basic name resolution function, turning a pathname into
|
||||
@ -1361,7 +1389,6 @@ static int link_path_walk(const char *name, struct nameidata *nd)
|
||||
|
||||
/* At this point we know we have a real path component. */
|
||||
for(;;) {
|
||||
struct inode *inode;
|
||||
unsigned long hash;
|
||||
struct qstr this;
|
||||
unsigned int c;
|
||||
@ -1414,34 +1441,16 @@ static int link_path_walk(const char *name, struct nameidata *nd)
|
||||
if (!*name)
|
||||
goto last_with_slashes;
|
||||
|
||||
/*
|
||||
* "." and ".." are special - ".." especially so because it has
|
||||
* to be able to know about the current root directory and
|
||||
* parent relationships.
|
||||
*/
|
||||
if (unlikely(type != LAST_NORM)) {
|
||||
if (handle_dots(nd, type))
|
||||
return -ECHILD;
|
||||
continue;
|
||||
}
|
||||
err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW);
|
||||
if (err < 0)
|
||||
return err;
|
||||
|
||||
/* This does the actual lookups.. */
|
||||
err = do_lookup(nd, &this, &next, &inode);
|
||||
if (err)
|
||||
break;
|
||||
|
||||
if (inode && inode->i_op->follow_link) {
|
||||
err = do_follow_link(inode, &next, nd);
|
||||
if (err) {
|
||||
err = do_follow_link(&next, nd);
|
||||
if (err)
|
||||
return err;
|
||||
nd->inode = nd->path.dentry->d_inode;
|
||||
} else {
|
||||
path_to_nameidata(&next, nd);
|
||||
nd->inode = inode;
|
||||
}
|
||||
err = -ENOENT;
|
||||
if (!nd->inode)
|
||||
break;
|
||||
err = -ENOTDIR;
|
||||
if (!nd->inode->i_op->lookup)
|
||||
break;
|
||||
@ -1453,36 +1462,27 @@ last_with_slashes:
|
||||
last_component:
|
||||
/* Clear LOOKUP_CONTINUE iff it was previously unset */
|
||||
nd->flags &= lookup_flags | ~LOOKUP_CONTINUE;
|
||||
if (lookup_flags & LOOKUP_PARENT)
|
||||
goto lookup_parent;
|
||||
if (unlikely(type != LAST_NORM))
|
||||
return handle_dots(nd, type);
|
||||
err = do_lookup(nd, &this, &next, &inode);
|
||||
if (err)
|
||||
break;
|
||||
if (inode && unlikely(inode->i_op->follow_link) &&
|
||||
(lookup_flags & LOOKUP_FOLLOW)) {
|
||||
err = do_follow_link(inode, &next, nd);
|
||||
if (lookup_flags & LOOKUP_PARENT) {
|
||||
nd->last = this;
|
||||
nd->last_type = type;
|
||||
return 0;
|
||||
}
|
||||
err = walk_component(nd, &next, &this, type,
|
||||
lookup_flags & LOOKUP_FOLLOW);
|
||||
if (err < 0)
|
||||
return err;
|
||||
if (err) {
|
||||
err = do_follow_link(&next, nd);
|
||||
if (err)
|
||||
return err;
|
||||
nd->inode = nd->path.dentry->d_inode;
|
||||
} else {
|
||||
path_to_nameidata(&next, nd);
|
||||
nd->inode = inode;
|
||||
}
|
||||
err = -ENOENT;
|
||||
if (!nd->inode)
|
||||
break;
|
||||
if (lookup_flags & LOOKUP_DIRECTORY) {
|
||||
err = -ENOTDIR;
|
||||
if (!nd->inode->i_op->lookup)
|
||||
break;
|
||||
}
|
||||
return 0;
|
||||
lookup_parent:
|
||||
nd->last = this;
|
||||
nd->last_type = type;
|
||||
return 0;
|
||||
}
|
||||
terminate_walk(nd);
|
||||
return err;
|
||||
@ -2068,7 +2068,6 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
|
||||
int want_write = 0;
|
||||
int acc_mode = op->acc_mode;
|
||||
struct file *filp;
|
||||
struct inode *inode;
|
||||
int error;
|
||||
|
||||
nd->flags &= ~LOOKUP_PARENT;
|
||||
@ -2111,24 +2110,12 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
|
||||
if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW))
|
||||
symlink_ok = 1;
|
||||
/* we _can_ be in RCU mode here */
|
||||
error = do_lookup(nd, &nd->last, path, &inode);
|
||||
if (error) {
|
||||
terminate_walk(nd);
|
||||
error = walk_component(nd, path, &nd->last, LAST_NORM,
|
||||
!symlink_ok);
|
||||
if (error < 0)
|
||||
return ERR_PTR(error);
|
||||
}
|
||||
if (!inode) {
|
||||
path_to_nameidata(path, nd);
|
||||
terminate_walk(nd);
|
||||
return ERR_PTR(-ENOENT);
|
||||
}
|
||||
if (unlikely(inode->i_op->follow_link && !symlink_ok)) {
|
||||
/* We drop rcu-walk here */
|
||||
if (nameidata_dentry_drop_rcu_maybe(nd, path->dentry))
|
||||
return ERR_PTR(-ECHILD);
|
||||
if (error) /* symlink */
|
||||
return NULL;
|
||||
}
|
||||
path_to_nameidata(path, nd);
|
||||
nd->inode = inode;
|
||||
/* sayonara */
|
||||
if (nd->flags & LOOKUP_RCU) {
|
||||
if (nameidata_drop_rcu_last(nd))
|
||||
@ -2137,7 +2124,7 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
|
||||
|
||||
error = -ENOTDIR;
|
||||
if (nd->flags & LOOKUP_DIRECTORY) {
|
||||
if (!inode->i_op->lookup)
|
||||
if (!nd->inode->i_op->lookup)
|
||||
goto exit;
|
||||
}
|
||||
audit_inode(pathname, nd->path.dentry);
|
||||
|
||||
Loading…
Reference in New Issue
Block a user