332 lines
9.0 KiB
C
332 lines
9.0 KiB
C
/*
|
|
kmod, the new module loader (replaces kerneld)
|
|
Kirk Petersen
|
|
|
|
Reorganized not to be a daemon by Adam Richter, with guidance
|
|
from Greg Zornetzer.
|
|
|
|
Modified to avoid chroot and file sharing problems.
|
|
Mikael Pettersson
|
|
|
|
Limit the concurrent number of kmod modprobes to catch loops from
|
|
"modprobe needs a service that is in a module".
|
|
Keith Owens <kaos@ocs.com.au> December 1999
|
|
|
|
Unblock all signals when we exec a usermode process.
|
|
Shuu Yamaguchi <shuu@wondernetworkresources.com> December 2000
|
|
|
|
call_usermodehelper wait flag, and remove exec_usermodehelper.
|
|
Rusty Russell <rusty@rustcorp.com.au> Jan 2003
|
|
*/
|
|
#include <linux/module.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/syscalls.h>
|
|
#include <linux/unistd.h>
|
|
#include <linux/kmod.h>
|
|
#include <linux/smp_lock.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/namespace.h>
|
|
#include <linux/completion.h>
|
|
#include <linux/file.h>
|
|
#include <linux/workqueue.h>
|
|
#include <linux/security.h>
|
|
#include <linux/mount.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/init.h>
|
|
#include <linux/resource.h>
|
|
#include <asm/uaccess.h>
|
|
|
|
extern int max_threads;
|
|
|
|
static struct workqueue_struct *khelper_wq;
|
|
|
|
#ifdef CONFIG_KMOD
|
|
|
|
/*
|
|
modprobe_path is set via /proc/sys.
|
|
*/
|
|
char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
|
|
|
|
/**
|
|
* request_module - try to load a kernel module
|
|
* @fmt: printf style format string for the name of the module
|
|
* @varargs: arguements as specified in the format string
|
|
*
|
|
* Load a module using the user mode module loader. The function returns
|
|
* zero on success or a negative errno code on failure. Note that a
|
|
* successful module load does not mean the module did not then unload
|
|
* and exit on an error of its own. Callers must check that the service
|
|
* they requested is now available not blindly invoke it.
|
|
*
|
|
* If module auto-loading support is disabled then this function
|
|
* becomes a no-operation.
|
|
*/
|
|
int request_module(const char *fmt, ...)
|
|
{
|
|
va_list args;
|
|
char module_name[MODULE_NAME_LEN];
|
|
unsigned int max_modprobes;
|
|
int ret;
|
|
char *argv[] = { modprobe_path, "-q", "--", module_name, NULL };
|
|
static char *envp[] = { "HOME=/",
|
|
"TERM=linux",
|
|
"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
|
|
NULL };
|
|
static atomic_t kmod_concurrent = ATOMIC_INIT(0);
|
|
#define MAX_KMOD_CONCURRENT 50 /* Completely arbitrary value - KAO */
|
|
static int kmod_loop_msg;
|
|
|
|
va_start(args, fmt);
|
|
ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
|
|
va_end(args);
|
|
if (ret >= MODULE_NAME_LEN)
|
|
return -ENAMETOOLONG;
|
|
|
|
/* If modprobe needs a service that is in a module, we get a recursive
|
|
* loop. Limit the number of running kmod threads to max_threads/2 or
|
|
* MAX_KMOD_CONCURRENT, whichever is the smaller. A cleaner method
|
|
* would be to run the parents of this process, counting how many times
|
|
* kmod was invoked. That would mean accessing the internals of the
|
|
* process tables to get the command line, proc_pid_cmdline is static
|
|
* and it is not worth changing the proc code just to handle this case.
|
|
* KAO.
|
|
*
|
|
* "trace the ppid" is simple, but will fail if someone's
|
|
* parent exits. I think this is as good as it gets. --RR
|
|
*/
|
|
max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT);
|
|
atomic_inc(&kmod_concurrent);
|
|
if (atomic_read(&kmod_concurrent) > max_modprobes) {
|
|
/* We may be blaming an innocent here, but unlikely */
|
|
if (kmod_loop_msg++ < 5)
|
|
printk(KERN_ERR
|
|
"request_module: runaway loop modprobe %s\n",
|
|
module_name);
|
|
atomic_dec(&kmod_concurrent);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
ret = call_usermodehelper(modprobe_path, argv, envp, 1);
|
|
atomic_dec(&kmod_concurrent);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(request_module);
|
|
#endif /* CONFIG_KMOD */
|
|
|
|
struct subprocess_info {
|
|
struct completion *complete;
|
|
char *path;
|
|
char **argv;
|
|
char **envp;
|
|
struct key *ring;
|
|
int wait;
|
|
int retval;
|
|
struct file *stdin;
|
|
};
|
|
|
|
/*
|
|
* This is the task which runs the usermode application
|
|
*/
|
|
static int ____call_usermodehelper(void *data)
|
|
{
|
|
struct subprocess_info *sub_info = data;
|
|
struct key *new_session, *old_session;
|
|
int retval;
|
|
|
|
/* Unblock all signals and set the session keyring. */
|
|
new_session = key_get(sub_info->ring);
|
|
flush_signals(current);
|
|
spin_lock_irq(¤t->sighand->siglock);
|
|
old_session = __install_session_keyring(current, new_session);
|
|
flush_signal_handlers(current, 1);
|
|
sigemptyset(¤t->blocked);
|
|
recalc_sigpending();
|
|
spin_unlock_irq(¤t->sighand->siglock);
|
|
|
|
key_put(old_session);
|
|
|
|
/* Install input pipe when needed */
|
|
if (sub_info->stdin) {
|
|
struct files_struct *f = current->files;
|
|
struct fdtable *fdt;
|
|
/* no races because files should be private here */
|
|
sys_close(0);
|
|
fd_install(0, sub_info->stdin);
|
|
spin_lock(&f->file_lock);
|
|
fdt = files_fdtable(f);
|
|
FD_SET(0, fdt->open_fds);
|
|
FD_CLR(0, fdt->close_on_exec);
|
|
spin_unlock(&f->file_lock);
|
|
|
|
/* and disallow core files too */
|
|
current->signal->rlim[RLIMIT_CORE] = (struct rlimit){0, 0};
|
|
}
|
|
|
|
/* We can run anywhere, unlike our parent keventd(). */
|
|
set_cpus_allowed(current, CPU_MASK_ALL);
|
|
|
|
retval = -EPERM;
|
|
if (current->fs->root)
|
|
retval = kernel_execve(sub_info->path,
|
|
sub_info->argv, sub_info->envp);
|
|
|
|
/* Exec failed? */
|
|
sub_info->retval = retval;
|
|
do_exit(0);
|
|
}
|
|
|
|
/* Keventd can't block, but this (a child) can. */
|
|
static int wait_for_helper(void *data)
|
|
{
|
|
struct subprocess_info *sub_info = data;
|
|
pid_t pid;
|
|
struct k_sigaction sa;
|
|
|
|
/* Install a handler: if SIGCLD isn't handled sys_wait4 won't
|
|
* populate the status, but will return -ECHILD. */
|
|
sa.sa.sa_handler = SIG_IGN;
|
|
sa.sa.sa_flags = 0;
|
|
siginitset(&sa.sa.sa_mask, sigmask(SIGCHLD));
|
|
do_sigaction(SIGCHLD, &sa, NULL);
|
|
allow_signal(SIGCHLD);
|
|
|
|
pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD);
|
|
if (pid < 0) {
|
|
sub_info->retval = pid;
|
|
} else {
|
|
int ret;
|
|
|
|
/*
|
|
* Normally it is bogus to call wait4() from in-kernel because
|
|
* wait4() wants to write the exit code to a userspace address.
|
|
* But wait_for_helper() always runs as keventd, and put_user()
|
|
* to a kernel address works OK for kernel threads, due to their
|
|
* having an mm_segment_t which spans the entire address space.
|
|
*
|
|
* Thus the __user pointer cast is valid here.
|
|
*/
|
|
sys_wait4(pid, (int __user *)&ret, 0, NULL);
|
|
|
|
/*
|
|
* If ret is 0, either ____call_usermodehelper failed and the
|
|
* real error code is already in sub_info->retval or
|
|
* sub_info->retval is 0 anyway, so don't mess with it then.
|
|
*/
|
|
if (ret)
|
|
sub_info->retval = ret;
|
|
}
|
|
|
|
complete(sub_info->complete);
|
|
return 0;
|
|
}
|
|
|
|
/* This is run by khelper thread */
|
|
static void __call_usermodehelper(void *data)
|
|
{
|
|
struct subprocess_info *sub_info = data;
|
|
pid_t pid;
|
|
int wait = sub_info->wait;
|
|
|
|
/* CLONE_VFORK: wait until the usermode helper has execve'd
|
|
* successfully We need the data structures to stay around
|
|
* until that is done. */
|
|
if (wait)
|
|
pid = kernel_thread(wait_for_helper, sub_info,
|
|
CLONE_FS | CLONE_FILES | SIGCHLD);
|
|
else
|
|
pid = kernel_thread(____call_usermodehelper, sub_info,
|
|
CLONE_VFORK | SIGCHLD);
|
|
|
|
if (pid < 0) {
|
|
sub_info->retval = pid;
|
|
complete(sub_info->complete);
|
|
} else if (!wait)
|
|
complete(sub_info->complete);
|
|
}
|
|
|
|
/**
|
|
* call_usermodehelper_keys - start a usermode application
|
|
* @path: pathname for the application
|
|
* @argv: null-terminated argument list
|
|
* @envp: null-terminated environment list
|
|
* @session_keyring: session keyring for process (NULL for an empty keyring)
|
|
* @wait: wait for the application to finish and return status.
|
|
*
|
|
* Runs a user-space application. The application is started
|
|
* asynchronously if wait is not set, and runs as a child of keventd.
|
|
* (ie. it runs with full root capabilities).
|
|
*
|
|
* Must be called from process context. Returns a negative error code
|
|
* if program was not execed successfully, or 0.
|
|
*/
|
|
int call_usermodehelper_keys(char *path, char **argv, char **envp,
|
|
struct key *session_keyring, int wait)
|
|
{
|
|
DECLARE_COMPLETION_ONSTACK(done);
|
|
struct subprocess_info sub_info = {
|
|
.complete = &done,
|
|
.path = path,
|
|
.argv = argv,
|
|
.envp = envp,
|
|
.ring = session_keyring,
|
|
.wait = wait,
|
|
.retval = 0,
|
|
};
|
|
DECLARE_WORK(work, __call_usermodehelper, &sub_info);
|
|
|
|
if (!khelper_wq)
|
|
return -EBUSY;
|
|
|
|
if (path[0] == '\0')
|
|
return 0;
|
|
|
|
queue_work(khelper_wq, &work);
|
|
wait_for_completion(&done);
|
|
return sub_info.retval;
|
|
}
|
|
EXPORT_SYMBOL(call_usermodehelper_keys);
|
|
|
|
int call_usermodehelper_pipe(char *path, char **argv, char **envp,
|
|
struct file **filp)
|
|
{
|
|
DECLARE_COMPLETION(done);
|
|
struct subprocess_info sub_info = {
|
|
.complete = &done,
|
|
.path = path,
|
|
.argv = argv,
|
|
.envp = envp,
|
|
.retval = 0,
|
|
};
|
|
struct file *f;
|
|
DECLARE_WORK(work, __call_usermodehelper, &sub_info);
|
|
|
|
if (!khelper_wq)
|
|
return -EBUSY;
|
|
|
|
if (path[0] == '\0')
|
|
return 0;
|
|
|
|
f = create_write_pipe();
|
|
if (!f)
|
|
return -ENOMEM;
|
|
*filp = f;
|
|
|
|
f = create_read_pipe(f);
|
|
if (!f) {
|
|
free_write_pipe(*filp);
|
|
return -ENOMEM;
|
|
}
|
|
sub_info.stdin = f;
|
|
|
|
queue_work(khelper_wq, &work);
|
|
wait_for_completion(&done);
|
|
return sub_info.retval;
|
|
}
|
|
EXPORT_SYMBOL(call_usermodehelper_pipe);
|
|
|
|
void __init usermodehelper_init(void)
|
|
{
|
|
khelper_wq = create_singlethread_workqueue("khelper");
|
|
BUG_ON(!khelper_wq);
|
|
}
|