From 102a0743326a03cd1a1202ceda21e175b7d3575c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:20:52 +0000
Subject: [PATCH] add new system file
---
kernel/fs/tracefs/inode.c | 157 ++++++++++++++--------------------------------------
1 files changed, 43 insertions(+), 114 deletions(-)
diff --git a/kernel/fs/tracefs/inode.c b/kernel/fs/tracefs/inode.c
index 3001165..c0f288a 100644
--- a/kernel/fs/tracefs/inode.c
+++ b/kernel/fs/tracefs/inode.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
/*
* inode.c - part of tracefs, a pseudo file system for activating tracing
*
@@ -5,12 +6,7 @@
*
* Copyright (C) 2014 Red Hat Inc, author: Steven Rostedt <srostedt@redhat.com>
*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License version
- * 2 as published by the Free Software Foundation.
- *
* tracefs is the file system that is used by the tracing infrastructure.
- *
*/
#include <linux/module.h>
@@ -20,6 +16,7 @@
#include <linux/namei.h>
#include <linux/tracefs.h>
#include <linux/fsnotify.h>
+#include <linux/security.h>
#include <linux/seq_file.h>
#include <linux/parser.h>
#include <linux/magic.h>
@@ -142,6 +139,8 @@
kuid_t uid;
kgid_t gid;
umode_t mode;
+ /* Opt_* bitfield. */
+ unsigned int opts;
};
enum {
@@ -199,7 +198,7 @@
if (!list_empty(&dentry->d_subdirs)) {
spin_unlock(&this_parent->d_lock);
- spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
+ spin_release(&dentry->d_lock.dep_map, _RET_IP_);
this_parent = dentry;
spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
goto repeat;
@@ -242,6 +241,7 @@
kgid_t gid;
char *p;
+ opts->opts = 0;
opts->mode = TRACEFS_DEFAULT_MODE;
while ((p = strsep(&data, ",")) != NULL) {
@@ -276,24 +276,36 @@
* but traditionally tracefs has ignored all mount options
*/
}
+
+ opts->opts |= BIT(token);
}
return 0;
}
-static int tracefs_apply_options(struct super_block *sb)
+static int tracefs_apply_options(struct super_block *sb, bool remount)
{
struct tracefs_fs_info *fsi = sb->s_fs_info;
struct inode *inode = sb->s_root->d_inode;
struct tracefs_mount_opts *opts = &fsi->mount_opts;
- inode->i_mode &= ~S_IALLUGO;
- inode->i_mode |= opts->mode;
+ /*
+ * On remount, only reset mode/uid/gid if they were provided as mount
+ * options.
+ */
- inode->i_uid = opts->uid;
+ if (!remount || opts->opts & BIT(Opt_mode)) {
+ inode->i_mode &= ~S_IALLUGO;
+ inode->i_mode |= opts->mode;
+ }
- /* Set all the group ids to the mount option */
- set_gid(sb->s_root, opts->gid);
+ if (!remount || opts->opts & BIT(Opt_uid))
+ inode->i_uid = opts->uid;
+
+ if (!remount || opts->opts & BIT(Opt_gid)) {
+ /* Set all the group ids to the mount option */
+ set_gid(sb->s_root, opts->gid);
+ }
return 0;
}
@@ -308,7 +320,7 @@
if (err)
goto fail;
- tracefs_apply_options(sb);
+ tracefs_apply_options(sb, true);
fail:
return err;
@@ -360,7 +372,7 @@
sb->s_op = &tracefs_super_operations;
- tracefs_apply_options(sb);
+ tracefs_apply_options(sb, false);
return 0;
@@ -406,7 +418,10 @@
parent = tracefs_mount->mnt_root;
inode_lock(parent->d_inode);
- dentry = lookup_one_len(name, parent, strlen(name));
+ if (unlikely(IS_DEADDIR(parent->d_inode)))
+ dentry = ERR_PTR(-ENOENT);
+ else
+ dentry = lookup_one_len(name, parent, strlen(name));
if (!IS_ERR(dentry) && dentry->d_inode) {
dput(dentry);
dentry = ERR_PTR(-EEXIST);
@@ -466,6 +481,9 @@
{
struct dentry *dentry;
struct inode *inode;
+
+ if (security_locked_down(LOCKDOWN_TRACEFS))
+ return NULL;
if (!(mode & S_IFMT))
mode |= S_IFREG;
@@ -535,6 +553,9 @@
*/
struct dentry *tracefs_create_dir(const char *name, struct dentry *parent)
{
+ if (security_locked_down(LOCKDOWN_TRACEFS))
+ return NULL;
+
return __create_dir(name, parent, &simple_dir_inode_operations);
}
@@ -576,119 +597,27 @@
return dentry;
}
-static int __tracefs_remove(struct dentry *dentry, struct dentry *parent)
+static void remove_one(struct dentry *victim)
{
- int ret = 0;
-
- if (simple_positive(dentry)) {
- if (dentry->d_inode) {
- dget(dentry);
- switch (dentry->d_inode->i_mode & S_IFMT) {
- case S_IFDIR:
- ret = simple_rmdir(parent->d_inode, dentry);
- break;
- default:
- simple_unlink(parent->d_inode, dentry);
- break;
- }
- if (!ret)
- d_delete(dentry);
- dput(dentry);
- }
- }
- return ret;
+ simple_release_fs(&tracefs_mount, &tracefs_mount_count);
}
/**
- * tracefs_remove - removes a file or directory from the tracefs filesystem
- * @dentry: a pointer to a the dentry of the file or directory to be
- * removed.
- *
- * This function removes a file or directory in tracefs that was previously
- * created with a call to another tracefs function (like
- * tracefs_create_file() or variants thereof.)
- */
-void tracefs_remove(struct dentry *dentry)
-{
- struct dentry *parent;
- int ret;
-
- if (IS_ERR_OR_NULL(dentry))
- return;
-
- parent = dentry->d_parent;
- inode_lock(parent->d_inode);
- ret = __tracefs_remove(dentry, parent);
- inode_unlock(parent->d_inode);
- if (!ret)
- simple_release_fs(&tracefs_mount, &tracefs_mount_count);
-}
-
-/**
- * tracefs_remove_recursive - recursively removes a directory
+ * tracefs_remove - recursively removes a directory
* @dentry: a pointer to a the dentry of the directory to be removed.
*
* This function recursively removes a directory tree in tracefs that
* was previously created with a call to another tracefs function
* (like tracefs_create_file() or variants thereof.)
*/
-void tracefs_remove_recursive(struct dentry *dentry)
+void tracefs_remove(struct dentry *dentry)
{
- struct dentry *child, *parent;
-
if (IS_ERR_OR_NULL(dentry))
return;
- parent = dentry;
- down:
- inode_lock(parent->d_inode);
- loop:
- /*
- * The parent->d_subdirs is protected by the d_lock. Outside that
- * lock, the child can be unlinked and set to be freed which can
- * use the d_u.d_child as the rcu head and corrupt this list.
- */
- spin_lock(&parent->d_lock);
- list_for_each_entry(child, &parent->d_subdirs, d_child) {
- if (!simple_positive(child))
- continue;
-
- /* perhaps simple_empty(child) makes more sense */
- if (!list_empty(&child->d_subdirs)) {
- spin_unlock(&parent->d_lock);
- inode_unlock(parent->d_inode);
- parent = child;
- goto down;
- }
-
- spin_unlock(&parent->d_lock);
-
- if (!__tracefs_remove(child, parent))
- simple_release_fs(&tracefs_mount, &tracefs_mount_count);
-
- /*
- * The parent->d_lock protects agaist child from unlinking
- * from d_subdirs. When releasing the parent->d_lock we can
- * no longer trust that the next pointer is valid.
- * Restart the loop. We'll skip this one with the
- * simple_positive() check.
- */
- goto loop;
- }
- spin_unlock(&parent->d_lock);
-
- inode_unlock(parent->d_inode);
- child = parent;
- parent = parent->d_parent;
- inode_lock(parent->d_inode);
-
- if (child != dentry)
- /* go up */
- goto loop;
-
- if (!__tracefs_remove(child, parent))
- simple_release_fs(&tracefs_mount, &tracefs_mount_count);
- inode_unlock(parent->d_inode);
+ simple_pin_fs(&trace_fs_type, &tracefs_mount, &tracefs_mount_count);
+ simple_recursive_removal(dentry, remove_one);
+ simple_release_fs(&tracefs_mount, &tracefs_mount_count);
}
/**
--
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