Current File : //proc/self/root/usr/share/systemtap/runtime/procfs.c
/* -*- linux-c -*-
*
* /proc command channels
* Copyright (C) 2007-2009 Red Hat Inc.
*
* This file is part of systemtap, and is free software. You can
* redistribute it and/or modify it under the terms of the GNU General
* Public License (GPL); either version 2, or (at your option) any
* later version.
*/
#ifndef _STP_PROCFS_C_
#define _STP_PROCFS_C_
#if (!defined(STAPCONF_PATH_LOOKUP) && !defined(STAPCONF_KERN_PATH_PARENT) \
&& !defined(STAPCONF_VFS_PATH_LOOKUP) && !defined(STAPCONF_KERN_PATH))
#error "Either path_lookup(), kern_path_parent(), vfs_path_lookup(), or kern_path() must be exported by the kernel."
#endif
#ifdef STAPCONF_KERN_PATH
#include <linux/namei.h>
#endif
#ifdef STAPCONF_VFS_PATH_LOOKUP
#include <linux/mount.h>
#include <linux/pid_namespace.h>
#endif
#include "proc_fs_compatibility.h"
#include "uidgid_compatibility.h"
#if defined(STAPCONF_PATH_LOOKUP) && !defined(STAPCONF_KERN_PATH_PARENT)
#define kern_path_parent(name, nameidata) \
path_lookup(name, LOOKUP_PARENT, nameidata)
#endif
/* If STAPCONF_PDE_DATA isn't defined, we're using the original /proc
* interface (where 'struct proc_dir_entry' isn't opaque). In this
* case allow the (undocumented) feature of slashes
* (i.e. subdirectories) in paths. */
#ifndef STAPCONF_PDE_DATA
#define _STP_ALLOW_PROCFS_PATH_SUBDIRS
#endif
/* The maximum number of files AND directories that can be opened.
* It would be great if the translator would emit this based on the actual
* number of needed files.
*/
#ifndef STP_MAX_PROCFS_FILES
#define STP_MAX_PROCFS_FILES 16
#endif
static int _stp_num_pde = 0;
static struct proc_dir_entry *_stp_pde[STP_MAX_PROCFS_FILES];
/* _stp_proc_root is the '/proc/systemtap/{module_name}' directory. */
static struct proc_dir_entry *_stp_proc_root = NULL;
static void _stp_close_procfs(void);
/*
* Removes '/proc/systemtap/{module_name}'. Notice we're leaving
* '/proc/systemtap' behind. There is no way on newer kernels to know
* if a procfs directory is empty.
*
* NB: this is suitable to call late in the module cleanup function,
* and does not rely on any other facilities in the runtime. PR19833.
* See also PR15408.
*/
static void _stp_rmdir_proc_module(void)
{
if (_stp_proc_root) {
proc_remove(_stp_proc_root);
_stp_proc_root = NULL;
}
}
/*
* Safely creates '/proc/systemtap' (if necessary) and
* '/proc/systemtap/{module_name}'.
*
* NB: this function is suitable to call from early in the the
* module-init function, and doesn't rely on any other facilities
* in our runtime. PR19833. See also PR15408.
*/
static int _stp_mkdir_proc_module(void)
{
int found = 0;
static char proc_root_name[STP_MODULE_NAME_LEN + sizeof("systemtap/")];
#if defined(STAPCONF_PATH_LOOKUP) || defined(STAPCONF_KERN_PATH_PARENT)
struct nameidata nd;
#else /* STAPCONF_VFS_PATH_LOOKUP or STAPCONF_KERN_PATH */
struct path path;
#if defined(STAPCONF_VFS_PATH_LOOKUP)
struct vfsmount *mnt;
#endif
int rc;
#endif /* STAPCONF_VFS_PATH_LOOKUP or STAPCONF_KERN_PATH */
if (_stp_proc_root != NULL)
return 0;
#if defined(STAPCONF_PATH_LOOKUP) || defined(STAPCONF_KERN_PATH_PARENT)
/* Why "/proc/systemtap/foo"? kern_path_parent() is basically
* the same thing as calling the old path_lookup() with flags
* set to LOOKUP_PARENT, which means to look up the parent of
* the path, which in this case is "/proc/systemtap". */
if (! kern_path_parent("/proc/systemtap/foo", &nd)) {
found = 1;
#ifdef STAPCONF_NAMEIDATA_CLEANUP
path_put(&nd.path);
#else /* !STAPCONF_NAMEIDATA_CLEANUP */
path_release(&nd);
#endif /* !STAPCONF_NAMEIDATA_CLEANUP */
}
#elif defined(STAPCONF_KERN_PATH)
/* Prefer kern_path() over vfs_path_lookup(), since on some
* kernels the declaration for vfs_path_lookup() was moved to
* a private header. */
/* See if '/proc/systemtap' exists. */
rc = kern_path("/proc/systemtap", 0, &path);
if (rc == 0) {
found = 1;
path_put (&path);
}
#else /* STAPCONF_VFS_PATH_LOOKUP */
/* See if '/proc/systemtap' exists. */
if (! init_pid_ns.proc_mnt) {
errk("Unable to create '/proc/systemap':"
" '/proc' doesn't exist.\n");
goto done;
}
mnt = init_pid_ns.proc_mnt;
rc = vfs_path_lookup(mnt->mnt_root, mnt, "systemtap", 0, &path);
if (rc == 0) {
found = 1;
path_put (&path);
}
#endif /* STAPCONF_VFS_PATH_LOOKUP */
/* If we couldn't find "/proc/systemtap", create it. */
if (!found) {
struct proc_dir_entry *de;
de = proc_mkdir ("systemtap", NULL);
if (de == NULL) {
errk("Unable to create '/proc/systemap':"
" proc_mkdir failed.\n");
goto done;
}
}
/* Create the "systemtap/{module_name} directory in procfs. */
strlcpy(proc_root_name, "systemtap/", sizeof(proc_root_name));
strlcat(proc_root_name, THIS_MODULE->name, sizeof(proc_root_name));
_stp_proc_root = proc_mkdir(proc_root_name, NULL);
#ifdef STAPCONF_PROCFS_OWNER
if (_stp_proc_root != NULL)
_stp_proc_root->owner = THIS_MODULE;
#endif
if (_stp_proc_root == NULL)
errk("Unable to create '/proc/systemap/%s':"
" proc_mkdir failed.\n", THIS_MODULE->name);
done:
return (_stp_proc_root) ? 0 : -EINVAL;
}
#ifdef _STP_ALLOW_PROCFS_PATH_SUBDIRS
/*
* This checks our local cache to see if we already made the dir.
*/
static struct proc_dir_entry *_stp_procfs_lookup(const char *dir, struct proc_dir_entry *parent)
{
int i;
for (i = 0; i <_stp_num_pde; i++) {
struct proc_dir_entry *pde = _stp_pde[i];
if (pde->parent == parent && !strcmp(dir, pde->name))
return pde;
}
return NULL;
}
#endif /* _STP_ALLOW_PROCFS_PATH_SUBDIRS */
static int _stp_create_procfs(const char *path,
const struct file_operations *fops, int perm,
void *data)
{
const char *p; char *next;
struct proc_dir_entry *last_dir, *de;
if (_stp_num_pde >= STP_MAX_PROCFS_FILES)
goto too_many;
last_dir = _stp_proc_root;
/* if no path, use default one */
if (strlen(path) == 0)
p = "command";
else
p = path;
#ifdef _STP_ALLOW_PROCFS_PATH_SUBDIRS
while ((next = strchr(p, '/'))) {
if (_stp_num_pde == STP_MAX_PROCFS_FILES)
goto too_many;
*next = 0;
de = _stp_procfs_lookup(p, last_dir);
if (de == NULL) {
last_dir = proc_mkdir(p, last_dir);
if (!last_dir) {
_stp_error("Could not create directory \"%s\"\n", p);
goto err;
}
_stp_pde[_stp_num_pde++] = last_dir;
#ifdef STAPCONF_PROCFS_OWNER
last_dir->owner = THIS_MODULE;
#endif
proc_set_user(last_dir, KUIDT_INIT(_stp_uid),
KGIDT_INIT(_stp_gid));
}
else {
last_dir = de;
}
p = next + 1;
}
#else /* !_STP_ALLOW_PROCFS_PATH_SUBDIRS */
if (strchr(p, '/') != NULL) {
_stp_error("Could not create path \"%s\","
" contains subdirectories\n", p);
goto err;
}
#endif /* !_STP_ALLOW_PROCFS_PATH_SUBDIRS */
if (_stp_num_pde == STP_MAX_PROCFS_FILES)
goto too_many;
de = proc_create_data(p, perm, last_dir, fops, data);
if (de == NULL)
return 0; // already created
#ifdef STAPCONF_PROCFS_OWNER
de->owner = THIS_MODULE;
#endif
proc_set_user(de, KUIDT_INIT(_stp_uid), KGIDT_INIT(_stp_gid));
_stp_pde[_stp_num_pde++] = de;
return 0;
too_many:
_stp_error("Attempted to open too many procfs files. Maximum is %d\n",
STP_MAX_PROCFS_FILES);
err:
_stp_close_procfs();
return -1;
}
static void _stp_close_procfs(void)
{
int i;
for (i = _stp_num_pde-1; i >= 0; i--) {
struct proc_dir_entry *pde = _stp_pde[i];
proc_remove(pde);
}
_stp_num_pde = 0;
}
#endif /* _STP_PROCFS_C_ */
Mini Shell