Maksytka/linux
1
1
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2025-12-01 07:26:02 +07:00
Code Issues Packages Projects Releases Wiki Activity

VFS: rename lookup_one_len family to lookup_noperm and remove permission check

Browse Source 
The lookup_one_len family of functions is (now) only used internally by
a filesystem on itself either
- in a context where permission checking is irrelevant such as by a
  virtual filesystem populating itself, or xfs accessing its ORPHANAGE
  or dquota accessing the quota file; or
- in a context where a permission check (MAY_EXEC on the parent) has just
  been performed such as a network filesystem finding in "silly-rename"
  file in the same directory.  This is also the context after the
  _parentat() functions where currently lookup_one_qstr_excl() is used.

So the permission check is pointless.

The name "one_len" is unhelpful in understanding the purpose of these
functions and should be changed.  Most of the callers pass the len as
"strlen()" so using a qstr and QSTR() can simplify the code.

This patch renames these functions (include lookup_positive_unlocked()
which is part of the family despite the name) to have a name based on
"lookup_noperm".  They are changed to receive a 'struct qstr' instead
of separate name and len.  In a few cases the use of QSTR() results in a
new call to strlen().

try_lookup_noperm() takes a pointer to a qstr instead of the whole
qstr.  This is consistent with d_hash_and_lookup() (which is nearly
identical) and useful for lookup_noperm_unlocked().

The new lookup_noperm_common() doesn't take a qstr yet.  That will be
tidied up in a subsequent patch.

Signed-off-by: NeilBrown <neil@brown.name>
Link: https://lore.kernel.org/r/20250319031545.2999807-5-neil@brown.name
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
NeilBrown
2025-03-19 14:01:35 +11:00
committed by Christian Brauner
parent 2011067c64
commit fa6fe07d15
25 changed files with 122 additions and 87 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
ipc/mqueue.c
View File

@@ -913,7 +913,7 @@ static int do_mq_open(const char __user *u_name, int oflag, umode_t mode,
ro = mnt_want_write(mnt); /* we'll drop it in any case */
inode_lock(d_inode(root));
path.dentry = lookup_one_len(name->name, root, strlen(name->name));
path.dentry = lookup_noperm(&QSTR(name->name), root);
if (IS_ERR(path.dentry)) {
error = PTR_ERR(path.dentry);
goto out_putfd;
@@ -969,8 +969,7 @@ SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
if (err)
goto out_name;
inode_lock_nested(d_inode(mnt->mnt_root), I_MUTEX_PARENT);
dentry = lookup_one_len(name->name, mnt->mnt_root,
strlen(name->name));
dentry = lookup_noperm(&QSTR(name->name), mnt->mnt_root);
if (IS_ERR(dentry)) {
err = PTR_ERR(dentry);
goto out_unlock;