linux/fs/tracefs/inode.c
Linus Torvalds 4d66020dce Tracing updates for 5.17:
New:
 
 - The Real Time Linux Analysis (RTLA) tool is added to the tools directory.
 
 - Can safely filter on user space pointers with: field.ustring ~ "match-string"
 
 - eprobes can now be filtered like any other event.
 
 - trace_marker(_raw) now uses stream_open() to allow multiple threads to safely
   write to it. Note, this could possibly break existing user space, but we will
   not know until we hear about it, and then can revert the change if need be.
 
 - New field in events to display when bottom halfs are disabled.
 
 - Sorting of the ftrace functions are now done at compile time instead of
   at bootup.
 
 Infrastructure changes to support future efforts:
 
 - Added __rel_loc type for trace events. Similar to __data_loc but the offset
   to the dynamic data is based off of the location of the descriptor and not
   the beginning of the event. Needed for user defined events.
 
 - Some simplification of event trigger code.
 
 - Make synthetic events process its callback better to not hinder other
   event callbacks that are registered. Needed for user defined events.
 
 And other small fixes and clean ups.
 -
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Merge tag 'trace-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:
 "New:

   - The Real Time Linux Analysis (RTLA) tool is added to the tools
     directory.

   - Can safely filter on user space pointers with: field.ustring ~
     "match-string"

   - eprobes can now be filtered like any other event.

   - trace_marker(_raw) now uses stream_open() to allow multiple threads
     to safely write to it. Note, this could possibly break existing
     user space, but we will not know until we hear about it, and then
     can revert the change if need be.

   - New field in events to display when bottom halfs are disabled.

   - Sorting of the ftrace functions are now done at compile time
     instead of at bootup.

  Infrastructure changes to support future efforts:

   - Added __rel_loc type for trace events. Similar to __data_loc but
     the offset to the dynamic data is based off of the location of the
     descriptor and not the beginning of the event. Needed for user
     defined events.

   - Some simplification of event trigger code.

   - Make synthetic events process its callback better to not hinder
     other event callbacks that are registered. Needed for user defined
     events.

  And other small fixes and cleanups"

* tag 'trace-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (50 commits)
  tracing: Add ustring operation to filtering string pointers
  rtla: Add rtla timerlat hist documentation
  rtla: Add rtla timerlat top documentation
  rtla: Add rtla timerlat documentation
  rtla: Add rtla osnoise hist documentation
  rtla: Add rtla osnoise top documentation
  rtla: Add rtla osnoise man page
  rtla: Add Documentation
  rtla/timerlat: Add timerlat hist mode
  rtla: Add timerlat tool and timelart top mode
  rtla/osnoise: Add the hist mode
  rtla/osnoise: Add osnoise top mode
  rtla: Add osnoise tool
  rtla: Helper functions for rtla
  rtla: Real-Time Linux Analysis tool
  tracing/osnoise: Properly unhook events if start_per_cpu_kthreads() fails
  tracing: Remove duplicate warnings when calling trace_create_file()
  tracing/kprobes: 'nmissed' not showed correctly for kretprobe
  tracing: Add test for user space strings when filtering on string pointers
  tracing: Have syscall trace events use trace_event_buffer_lock_reserve()
  ...
2022-01-16 10:15:32 +02:00

630 lines
16 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* inode.c - part of tracefs, a pseudo file system for activating tracing
*
* Based on debugfs by: Greg Kroah-Hartman <greg@kroah.com>
*
* Copyright (C) 2014 Red Hat Inc, author: Steven Rostedt <srostedt@redhat.com>
*
* tracefs is the file system that is used by the tracing infrastructure.
*/
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/kobject.h>
#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>
#include <linux/slab.h>
#define TRACEFS_DEFAULT_MODE 0700
static struct vfsmount *tracefs_mount;
static int tracefs_mount_count;
static bool tracefs_registered;
static ssize_t default_read_file(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
return 0;
}
static ssize_t default_write_file(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
return count;
}
static const struct file_operations tracefs_file_operations = {
.read = default_read_file,
.write = default_write_file,
.open = simple_open,
.llseek = noop_llseek,
};
static struct tracefs_dir_ops {
int (*mkdir)(const char *name);
int (*rmdir)(const char *name);
} tracefs_ops __ro_after_init;
static char *get_dname(struct dentry *dentry)
{
const char *dname;
char *name;
int len = dentry->d_name.len;
dname = dentry->d_name.name;
name = kmalloc(len + 1, GFP_KERNEL);
if (!name)
return NULL;
memcpy(name, dname, len);
name[len] = 0;
return name;
}
static int tracefs_syscall_mkdir(struct user_namespace *mnt_userns,
struct inode *inode, struct dentry *dentry,
umode_t mode)
{
char *name;
int ret;
name = get_dname(dentry);
if (!name)
return -ENOMEM;
/*
* The mkdir call can call the generic functions that create
* the files within the tracefs system. It is up to the individual
* mkdir routine to handle races.
*/
inode_unlock(inode);
ret = tracefs_ops.mkdir(name);
inode_lock(inode);
kfree(name);
return ret;
}
static int tracefs_syscall_rmdir(struct inode *inode, struct dentry *dentry)
{
char *name;
int ret;
name = get_dname(dentry);
if (!name)
return -ENOMEM;
/*
* The rmdir call can call the generic functions that create
* the files within the tracefs system. It is up to the individual
* rmdir routine to handle races.
* This time we need to unlock not only the parent (inode) but
* also the directory that is being deleted.
*/
inode_unlock(inode);
inode_unlock(d_inode(dentry));
ret = tracefs_ops.rmdir(name);
inode_lock_nested(inode, I_MUTEX_PARENT);
inode_lock(d_inode(dentry));
kfree(name);
return ret;
}
static const struct inode_operations tracefs_dir_inode_operations = {
.lookup = simple_lookup,
.mkdir = tracefs_syscall_mkdir,
.rmdir = tracefs_syscall_rmdir,
};
static struct inode *tracefs_get_inode(struct super_block *sb)
{
struct inode *inode = new_inode(sb);
if (inode) {
inode->i_ino = get_next_ino();
inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
}
return inode;
}
struct tracefs_mount_opts {
kuid_t uid;
kgid_t gid;
umode_t mode;
};
enum {
Opt_uid,
Opt_gid,
Opt_mode,
Opt_err
};
static const match_table_t tokens = {
{Opt_uid, "uid=%u"},
{Opt_gid, "gid=%u"},
{Opt_mode, "mode=%o"},
{Opt_err, NULL}
};
struct tracefs_fs_info {
struct tracefs_mount_opts mount_opts;
};
static void change_gid(struct dentry *dentry, kgid_t gid)
{
if (!dentry->d_inode)
return;
dentry->d_inode->i_gid = gid;
}
/*
* Taken from d_walk, but without he need for handling renames.
* Nothing can be renamed while walking the list, as tracefs
* does not support renames. This is only called when mounting
* or remounting the file system, to set all the files to
* the given gid.
*/
static void set_gid(struct dentry *parent, kgid_t gid)
{
struct dentry *this_parent;
struct list_head *next;
this_parent = parent;
spin_lock(&this_parent->d_lock);
change_gid(this_parent, gid);
repeat:
next = this_parent->d_subdirs.next;
resume:
while (next != &this_parent->d_subdirs) {
struct list_head *tmp = next;
struct dentry *dentry = list_entry(tmp, struct dentry, d_child);
next = tmp->next;
spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
change_gid(dentry, gid);
if (!list_empty(&dentry->d_subdirs)) {
spin_unlock(&this_parent->d_lock);
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;
}
spin_unlock(&dentry->d_lock);
}
/*
* All done at this level ... ascend and resume the search.
*/
rcu_read_lock();
ascend:
if (this_parent != parent) {
struct dentry *child = this_parent;
this_parent = child->d_parent;
spin_unlock(&child->d_lock);
spin_lock(&this_parent->d_lock);
/* go into the first sibling still alive */
do {
next = child->d_child.next;
if (next == &this_parent->d_subdirs)
goto ascend;
child = list_entry(next, struct dentry, d_child);
} while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED));
rcu_read_unlock();
goto resume;
}
rcu_read_unlock();
spin_unlock(&this_parent->d_lock);
return;
}
static int tracefs_parse_options(char *data, struct tracefs_mount_opts *opts)
{
substring_t args[MAX_OPT_ARGS];
int option;
int token;
kuid_t uid;
kgid_t gid;
char *p;
opts->mode = TRACEFS_DEFAULT_MODE;
while ((p = strsep(&data, ",")) != NULL) {
if (!*p)
continue;
token = match_token(p, tokens, args);
switch (token) {
case Opt_uid:
if (match_int(&args[0], &option))
return -EINVAL;
uid = make_kuid(current_user_ns(), option);
if (!uid_valid(uid))
return -EINVAL;
opts->uid = uid;
break;
case Opt_gid:
if (match_int(&args[0], &option))
return -EINVAL;
gid = make_kgid(current_user_ns(), option);
if (!gid_valid(gid))
return -EINVAL;
opts->gid = gid;
set_gid(tracefs_mount->mnt_root, gid);
break;
case Opt_mode:
if (match_octal(&args[0], &option))
return -EINVAL;
opts->mode = option & S_IALLUGO;
break;
/*
* We might like to report bad mount options here;
* but traditionally tracefs has ignored all mount options
*/
}
}
return 0;
}
static int tracefs_apply_options(struct super_block *sb)
{
struct tracefs_fs_info *fsi = sb->s_fs_info;
struct inode *inode = d_inode(sb->s_root);
struct tracefs_mount_opts *opts = &fsi->mount_opts;
inode->i_mode &= ~S_IALLUGO;
inode->i_mode |= opts->mode;
inode->i_uid = opts->uid;
inode->i_gid = opts->gid;
return 0;
}
static int tracefs_remount(struct super_block *sb, int *flags, char *data)
{
int err;
struct tracefs_fs_info *fsi = sb->s_fs_info;
sync_filesystem(sb);
err = tracefs_parse_options(data, &fsi->mount_opts);
if (err)
goto fail;
tracefs_apply_options(sb);
fail:
return err;
}
static int tracefs_show_options(struct seq_file *m, struct dentry *root)
{
struct tracefs_fs_info *fsi = root->d_sb->s_fs_info;
struct tracefs_mount_opts *opts = &fsi->mount_opts;
if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
seq_printf(m, ",uid=%u",
from_kuid_munged(&init_user_ns, opts->uid));
if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
seq_printf(m, ",gid=%u",
from_kgid_munged(&init_user_ns, opts->gid));
if (opts->mode != TRACEFS_DEFAULT_MODE)
seq_printf(m, ",mode=%o", opts->mode);
return 0;
}
static const struct super_operations tracefs_super_operations = {
.statfs = simple_statfs,
.remount_fs = tracefs_remount,
.show_options = tracefs_show_options,
};
static int trace_fill_super(struct super_block *sb, void *data, int silent)
{
static const struct tree_descr trace_files[] = {{""}};
struct tracefs_fs_info *fsi;
int err;
fsi = kzalloc(sizeof(struct tracefs_fs_info), GFP_KERNEL);
sb->s_fs_info = fsi;
if (!fsi) {
err = -ENOMEM;
goto fail;
}
err = tracefs_parse_options(data, &fsi->mount_opts);
if (err)
goto fail;
err = simple_fill_super(sb, TRACEFS_MAGIC, trace_files);
if (err)
goto fail;
sb->s_op = &tracefs_super_operations;
tracefs_apply_options(sb);
return 0;
fail:
kfree(fsi);
sb->s_fs_info = NULL;
return err;
}
static struct dentry *trace_mount(struct file_system_type *fs_type,
int flags, const char *dev_name,
void *data)
{
return mount_single(fs_type, flags, data, trace_fill_super);
}
static struct file_system_type trace_fs_type = {
.owner = THIS_MODULE,
.name = "tracefs",
.mount = trace_mount,
.kill_sb = kill_litter_super,
};
MODULE_ALIAS_FS("tracefs");
static struct dentry *start_creating(const char *name, struct dentry *parent)
{
struct dentry *dentry;
int error;
pr_debug("tracefs: creating file '%s'\n",name);
error = simple_pin_fs(&trace_fs_type, &tracefs_mount,
&tracefs_mount_count);
if (error)
return ERR_PTR(error);
/* If the parent is not specified, we create it in the root.
* We need the root dentry to do this, which is in the super
* block. A pointer to that is in the struct vfsmount that we
* have around.
*/
if (!parent)
parent = tracefs_mount->mnt_root;
inode_lock(d_inode(parent));
if (unlikely(IS_DEADDIR(d_inode(parent))))
dentry = ERR_PTR(-ENOENT);
else
dentry = lookup_one_len(name, parent, strlen(name));
if (!IS_ERR(dentry) && d_inode(dentry)) {
dput(dentry);
dentry = ERR_PTR(-EEXIST);
}
if (IS_ERR(dentry)) {
inode_unlock(d_inode(parent));
simple_release_fs(&tracefs_mount, &tracefs_mount_count);
}
return dentry;
}
static struct dentry *failed_creating(struct dentry *dentry)
{
inode_unlock(d_inode(dentry->d_parent));
dput(dentry);
simple_release_fs(&tracefs_mount, &tracefs_mount_count);
return NULL;
}
static struct dentry *end_creating(struct dentry *dentry)
{
inode_unlock(d_inode(dentry->d_parent));
return dentry;
}
/**
* tracefs_create_file - create a file in the tracefs filesystem
* @name: a pointer to a string containing the name of the file to create.
* @mode: the permission that the file should have.
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is NULL, then the
* file will be created in the root of the tracefs filesystem.
* @data: a pointer to something that the caller will want to get to later
* on. The inode.i_private pointer will point to this value on
* the open() call.
* @fops: a pointer to a struct file_operations that should be used for
* this file.
*
* This is the basic "create a file" function for tracefs. It allows for a
* wide range of flexibility in creating a file, or a directory (if you want
* to create a directory, the tracefs_create_dir() function is
* recommended to be used instead.)
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the tracefs_remove() function when the file is
* to be removed (no automatic cleanup happens if your module is unloaded,
* you are responsible here.) If an error occurs, %NULL will be returned.
*
* If tracefs is not enabled in the kernel, the value -%ENODEV will be
* returned.
*/
struct dentry *tracefs_create_file(const char *name, umode_t mode,
struct dentry *parent, void *data,
const struct file_operations *fops)
{
struct dentry *dentry;
struct inode *inode;
if (security_locked_down(LOCKDOWN_TRACEFS))
return NULL;
if (!(mode & S_IFMT))
mode |= S_IFREG;
BUG_ON(!S_ISREG(mode));
dentry = start_creating(name, parent);
if (IS_ERR(dentry))
return NULL;
inode = tracefs_get_inode(dentry->d_sb);
if (unlikely(!inode))
return failed_creating(dentry);
inode->i_mode = mode;
inode->i_fop = fops ? fops : &tracefs_file_operations;
inode->i_private = data;
inode->i_uid = d_inode(dentry->d_parent)->i_uid;
inode->i_gid = d_inode(dentry->d_parent)->i_gid;
d_instantiate(dentry, inode);
fsnotify_create(d_inode(dentry->d_parent), dentry);
return end_creating(dentry);
}
static struct dentry *__create_dir(const char *name, struct dentry *parent,
const struct inode_operations *ops)
{
struct dentry *dentry = start_creating(name, parent);
struct inode *inode;
if (IS_ERR(dentry))
return NULL;
inode = tracefs_get_inode(dentry->d_sb);
if (unlikely(!inode))
return failed_creating(dentry);
/* Do not set bits for OTH */
inode->i_mode = S_IFDIR | S_IRWXU | S_IRUSR| S_IRGRP | S_IXUSR | S_IXGRP;
inode->i_op = ops;
inode->i_fop = &simple_dir_operations;
inode->i_uid = d_inode(dentry->d_parent)->i_uid;
inode->i_gid = d_inode(dentry->d_parent)->i_gid;
/* directory inodes start off with i_nlink == 2 (for "." entry) */
inc_nlink(inode);
d_instantiate(dentry, inode);
inc_nlink(d_inode(dentry->d_parent));
fsnotify_mkdir(d_inode(dentry->d_parent), dentry);
return end_creating(dentry);
}
/**
* tracefs_create_dir - create a directory in the tracefs filesystem
* @name: a pointer to a string containing the name of the directory to
* create.
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is NULL, then the
* directory will be created in the root of the tracefs filesystem.
*
* This function creates a directory in tracefs with the given name.
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the tracefs_remove() function when the file is
* to be removed. If an error occurs, %NULL will be returned.
*
* If tracing is not enabled in the kernel, the value -%ENODEV will be
* returned.
*/
struct dentry *tracefs_create_dir(const char *name, struct dentry *parent)
{
return __create_dir(name, parent, &simple_dir_inode_operations);
}
/**
* tracefs_create_instance_dir - create the tracing instances directory
* @name: The name of the instances directory to create
* @parent: The parent directory that the instances directory will exist
* @mkdir: The function to call when a mkdir is performed.
* @rmdir: The function to call when a rmdir is performed.
*
* Only one instances directory is allowed.
*
* The instances directory is special as it allows for mkdir and rmdir to
* to be done by userspace. When a mkdir or rmdir is performed, the inode
* locks are released and the methods passed in (@mkdir and @rmdir) are
* called without locks and with the name of the directory being created
* within the instances directory.
*
* Returns the dentry of the instances directory.
*/
__init struct dentry *tracefs_create_instance_dir(const char *name,
struct dentry *parent,
int (*mkdir)(const char *name),
int (*rmdir)(const char *name))
{
struct dentry *dentry;
/* Only allow one instance of the instances directory. */
if (WARN_ON(tracefs_ops.mkdir || tracefs_ops.rmdir))
return NULL;
dentry = __create_dir(name, parent, &tracefs_dir_inode_operations);
if (!dentry)
return NULL;
tracefs_ops.mkdir = mkdir;
tracefs_ops.rmdir = rmdir;
return dentry;
}
static void remove_one(struct dentry *victim)
{
simple_release_fs(&tracefs_mount, &tracefs_mount_count);
}
/**
* 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(struct dentry *dentry)
{
if (IS_ERR_OR_NULL(dentry))
return;
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);
}
/**
* tracefs_initialized - Tells whether tracefs has been registered
*/
bool tracefs_initialized(void)
{
return tracefs_registered;
}
static int __init tracefs_init(void)
{
int retval;
retval = sysfs_create_mount_point(kernel_kobj, "tracing");
if (retval)
return -EINVAL;
retval = register_filesystem(&trace_fs_type);
if (!retval)
tracefs_registered = true;
return retval;
}
core_initcall(tracefs_init);