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Diffstat (limited to 'fs/configfs/symlink.c')
-rw-r--r--fs/configfs/symlink.c197
1 files changed, 86 insertions, 111 deletions
diff --git a/fs/configfs/symlink.c b/fs/configfs/symlink.c
index 91eac6c55e07..dc5dbf6a81d7 100644
--- a/fs/configfs/symlink.c
+++ b/fs/configfs/symlink.c
@@ -55,41 +55,63 @@ static void fill_item_path(struct config_item * item, char * buffer, int length)
}
}
+static int configfs_get_target_path(struct config_item *item,
+ struct config_item *target, char *path)
+{
+ int depth, size;
+ char *s;
+
+ depth = item_depth(item);
+ size = item_path_length(target) + depth * 3 - 1;
+ if (size > PATH_MAX)
+ return -ENAMETOOLONG;
+
+ pr_debug("%s: depth = %d, size = %d\n", __func__, depth, size);
+
+ for (s = path; depth--; s += 3)
+ strcpy(s,"../");
+
+ fill_item_path(target, path, size);
+ pr_debug("%s: path = '%s'\n", __func__, path);
+ return 0;
+}
+
static int create_link(struct config_item *parent_item,
struct config_item *item,
struct dentry *dentry)
{
struct configfs_dirent *target_sd = item->ci_dentry->d_fsdata;
- struct configfs_symlink *sl;
+ char *body;
int ret;
- ret = -ENOENT;
if (!configfs_dirent_is_ready(target_sd))
- goto out;
- ret = -ENOMEM;
- sl = kmalloc(sizeof(struct configfs_symlink), GFP_KERNEL);
- if (sl) {
+ return -ENOENT;
+
+ body = kzalloc(PAGE_SIZE, GFP_KERNEL);
+ if (!body)
+ return -ENOMEM;
+
+ configfs_get(target_sd);
+ spin_lock(&configfs_dirent_lock);
+ if (target_sd->s_type & CONFIGFS_USET_DROPPING) {
+ spin_unlock(&configfs_dirent_lock);
+ configfs_put(target_sd);
+ kfree(body);
+ return -ENOENT;
+ }
+ target_sd->s_links++;
+ spin_unlock(&configfs_dirent_lock);
+ ret = configfs_get_target_path(item, item, body);
+ if (!ret)
+ ret = configfs_create_link(target_sd, parent_item->ci_dentry,
+ dentry, body);
+ if (ret) {
spin_lock(&configfs_dirent_lock);
- if (target_sd->s_type & CONFIGFS_USET_DROPPING) {
- spin_unlock(&configfs_dirent_lock);
- kfree(sl);
- return -ENOENT;
- }
- sl->sl_target = config_item_get(item);
- list_add(&sl->sl_list, &target_sd->s_links);
+ target_sd->s_links--;
spin_unlock(&configfs_dirent_lock);
- ret = configfs_create_link(sl, parent_item->ci_dentry,
- dentry);
- if (ret) {
- spin_lock(&configfs_dirent_lock);
- list_del_init(&sl->sl_list);
- spin_unlock(&configfs_dirent_lock);
- config_item_put(item);
- kfree(sl);
- }
+ configfs_put(target_sd);
+ kfree(body);
}
-
-out:
return ret;
}
@@ -131,9 +153,8 @@ int configfs_symlink(struct inode *dir, struct dentry *dentry, const char *symna
* Fake invisibility if dir belongs to a group/default groups hierarchy
* being attached
*/
- ret = -ENOENT;
if (!configfs_dirent_is_ready(sd))
- goto out;
+ return -ENOENT;
parent_item = configfs_get_config_item(dentry->d_parent);
type = parent_item->ci_type;
@@ -143,11 +164,42 @@ int configfs_symlink(struct inode *dir, struct dentry *dentry, const char *symna
!type->ct_item_ops->allow_link)
goto out_put;
+ /*
+ * This is really sick. What they wanted was a hybrid of
+ * link(2) and symlink(2) - they wanted the target resolved
+ * at syscall time (as link(2) would've done), be a directory
+ * (which link(2) would've refused to do) *AND* be a deep
+ * fucking magic, making the target busy from rmdir POV.
+ * symlink(2) is nothing of that sort, and the locking it
+ * gets matches the normal symlink(2) semantics. Without
+ * attempts to resolve the target (which might very well
+ * not even exist yet) done prior to locking the parent
+ * directory. This perversion, OTOH, needs to resolve
+ * the target, which would lead to obvious deadlocks if
+ * attempted with any directories locked.
+ *
+ * Unfortunately, that garbage is userland ABI and we should've
+ * said "no" back in 2005. Too late now, so we get to
+ * play very ugly games with locking.
+ *
+ * Try *ANYTHING* of that sort in new code, and you will
+ * really regret it. Just ask yourself - what could a BOFH
+ * do to me and do I want to find it out first-hand?
+ *
+ * AV, a thoroughly annoyed bastard.
+ */
+ inode_unlock(dir);
ret = get_target(symname, &path, &target_item, dentry->d_sb);
+ inode_lock(dir);
if (ret)
goto out_put;
- ret = type->ct_item_ops->allow_link(parent_item, target_item);
+ if (dentry->d_inode || d_unhashed(dentry))
+ ret = -EEXIST;
+ else
+ ret = inode_permission(dir, MAY_WRITE | MAY_EXEC);
+ if (!ret)
+ ret = type->ct_item_ops->allow_link(parent_item, target_item);
if (!ret) {
mutex_lock(&configfs_symlink_mutex);
ret = create_link(parent_item, target_item, dentry);
@@ -162,15 +214,12 @@ int configfs_symlink(struct inode *dir, struct dentry *dentry, const char *symna
out_put:
config_item_put(parent_item);
-
-out:
return ret;
}
int configfs_unlink(struct inode *dir, struct dentry *dentry)
{
- struct configfs_dirent *sd = dentry->d_fsdata;
- struct configfs_symlink *sl;
+ struct configfs_dirent *sd = dentry->d_fsdata, *target_sd;
struct config_item *parent_item;
const struct config_item_type *type;
int ret;
@@ -179,7 +228,7 @@ int configfs_unlink(struct inode *dir, struct dentry *dentry)
if (!(sd->s_type & CONFIGFS_ITEM_LINK))
goto out;
- sl = sd->s_element;
+ target_sd = sd->s_element;
parent_item = configfs_get_config_item(dentry->d_parent);
type = parent_item->ci_type;
@@ -193,21 +242,18 @@ int configfs_unlink(struct inode *dir, struct dentry *dentry)
/*
* drop_link() must be called before
- * list_del_init(&sl->sl_list), so that the order of
+ * decrementing target's ->s_links, so that the order of
* drop_link(this, target) and drop_item(target) is preserved.
*/
if (type && type->ct_item_ops &&
type->ct_item_ops->drop_link)
type->ct_item_ops->drop_link(parent_item,
- sl->sl_target);
+ target_sd->s_element);
spin_lock(&configfs_dirent_lock);
- list_del_init(&sl->sl_list);
+ target_sd->s_links--;
spin_unlock(&configfs_dirent_lock);
-
- /* Put reference from create_link() */
- config_item_put(sl->sl_target);
- kfree(sl);
+ configfs_put(target_sd);
config_item_put(parent_item);
@@ -217,79 +263,8 @@ out:
return ret;
}
-static int configfs_get_target_path(struct config_item * item, struct config_item * target,
- char *path)
-{
- char * s;
- int depth, size;
-
- depth = item_depth(item);
- size = item_path_length(target) + depth * 3 - 1;
- if (size > PATH_MAX)
- return -ENAMETOOLONG;
-
- pr_debug("%s: depth = %d, size = %d\n", __func__, depth, size);
-
- for (s = path; depth--; s += 3)
- strcpy(s,"../");
-
- fill_item_path(target, path, size);
- pr_debug("%s: path = '%s'\n", __func__, path);
-
- return 0;
-}
-
-static int configfs_getlink(struct dentry *dentry, char * path)
-{
- struct config_item *item, *target_item;
- int error = 0;
-
- item = configfs_get_config_item(dentry->d_parent);
- if (!item)
- return -EINVAL;
-
- target_item = configfs_get_config_item(dentry);
- if (!target_item) {
- config_item_put(item);
- return -EINVAL;
- }
-
- down_read(&configfs_rename_sem);
- error = configfs_get_target_path(item, target_item, path);
- up_read(&configfs_rename_sem);
-
- config_item_put(item);
- config_item_put(target_item);
- return error;
-
-}
-
-static const char *configfs_get_link(struct dentry *dentry,
- struct inode *inode,
- struct delayed_call *done)
-{
- char *body;
- int error;
-
- if (!dentry)
- return ERR_PTR(-ECHILD);
-
- body = kzalloc(PAGE_SIZE, GFP_KERNEL);
- if (!body)
- return ERR_PTR(-ENOMEM);
-
- error = configfs_getlink(dentry, body);
- if (!error) {
- set_delayed_call(done, kfree_link, body);
- return body;
- }
-
- kfree(body);
- return ERR_PTR(error);
-}
-
const struct inode_operations configfs_symlink_inode_operations = {
- .get_link = configfs_get_link,
+ .get_link = simple_get_link,
.setattr = configfs_setattr,
};
generated by cgit v1.2.3 (git 2.39.1) at 2024-04-19 20:13:12 +0000