/*
- 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
-*/
+ * kmod - the kernel module loader
+ */
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/sched/task.h>
#include <trace/events/module.h>
-#define CAP_BSET (void *)1
-#define CAP_PI (void *)2
-
-static kernel_cap_t usermodehelper_bset = CAP_FULL_SET;
-static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET;
-static DEFINE_SPINLOCK(umh_sysctl_lock);
-static DECLARE_RWSEM(umhelper_sem);
-
#ifdef CONFIG_MODULES
/*
* Assuming:
EXPORT_SYMBOL(__request_module);
#endif /* CONFIG_MODULES */
-
-static void call_usermodehelper_freeinfo(struct subprocess_info *info)
-{
- if (info->cleanup)
- (*info->cleanup)(info);
- kfree(info);
-}
-
-static void umh_complete(struct subprocess_info *sub_info)
-{
- struct completion *comp = xchg(&sub_info->complete, NULL);
- /*
- * See call_usermodehelper_exec(). If xchg() returns NULL
- * we own sub_info, the UMH_KILLABLE caller has gone away
- * or the caller used UMH_NO_WAIT.
- */
- if (comp)
- complete(comp);
- else
- call_usermodehelper_freeinfo(sub_info);
-}
-
-/*
- * This is the task which runs the usermode application
- */
-static int call_usermodehelper_exec_async(void *data)
-{
- struct subprocess_info *sub_info = data;
- struct cred *new;
- int retval;
-
- spin_lock_irq(¤t->sighand->siglock);
- flush_signal_handlers(current, 1);
- spin_unlock_irq(¤t->sighand->siglock);
-
- /*
- * Our parent (unbound workqueue) runs with elevated scheduling
- * priority. Avoid propagating that into the userspace child.
- */
- set_user_nice(current, 0);
-
- retval = -ENOMEM;
- new = prepare_kernel_cred(current);
- if (!new)
- goto out;
-
- spin_lock(&umh_sysctl_lock);
- new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset);
- new->cap_inheritable = cap_intersect(usermodehelper_inheritable,
- new->cap_inheritable);
- spin_unlock(&umh_sysctl_lock);
-
- if (sub_info->init) {
- retval = sub_info->init(sub_info, new);
- if (retval) {
- abort_creds(new);
- goto out;
- }
- }
-
- commit_creds(new);
-
- retval = do_execve(getname_kernel(sub_info->path),
- (const char __user *const __user *)sub_info->argv,
- (const char __user *const __user *)sub_info->envp);
-out:
- sub_info->retval = retval;
- /*
- * call_usermodehelper_exec_sync() will call umh_complete
- * if UHM_WAIT_PROC.
- */
- if (!(sub_info->wait & UMH_WAIT_PROC))
- umh_complete(sub_info);
- if (!retval)
- return 0;
- do_exit(0);
-}
-
-/* Handles UMH_WAIT_PROC. */
-static void call_usermodehelper_exec_sync(struct subprocess_info *sub_info)
-{
- pid_t pid;
-
- /* If SIGCLD is ignored sys_wait4 won't populate the status. */
- kernel_sigaction(SIGCHLD, SIG_DFL);
- pid = kernel_thread(call_usermodehelper_exec_async, sub_info, SIGCHLD);
- if (pid < 0) {
- sub_info->retval = pid;
- } else {
- int ret = -ECHILD;
- /*
- * Normally it is bogus to call wait4() from in-kernel because
- * wait4() wants to write the exit code to a userspace address.
- * But call_usermodehelper_exec_sync() always runs as kernel
- * thread (workqueue) 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_exec_async 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;
- }
-
- /* Restore default kernel sig handler */
- kernel_sigaction(SIGCHLD, SIG_IGN);
-
- umh_complete(sub_info);
-}
-
-/*
- * We need to create the usermodehelper kernel thread from a task that is affine
- * to an optimized set of CPUs (or nohz housekeeping ones) such that they
- * inherit a widest affinity irrespective of call_usermodehelper() callers with
- * possibly reduced affinity (eg: per-cpu workqueues). We don't want
- * usermodehelper targets to contend a busy CPU.
- *
- * Unbound workqueues provide such wide affinity and allow to block on
- * UMH_WAIT_PROC requests without blocking pending request (up to some limit).
- *
- * Besides, workqueues provide the privilege level that caller might not have
- * to perform the usermodehelper request.
- *
- */
-static void call_usermodehelper_exec_work(struct work_struct *work)
-{
- struct subprocess_info *sub_info =
- container_of(work, struct subprocess_info, work);
-
- if (sub_info->wait & UMH_WAIT_PROC) {
- call_usermodehelper_exec_sync(sub_info);
- } else {
- pid_t pid;
- /*
- * Use CLONE_PARENT to reparent it to kthreadd; we do not
- * want to pollute current->children, and we need a parent
- * that always ignores SIGCHLD to ensure auto-reaping.
- */
- pid = kernel_thread(call_usermodehelper_exec_async, sub_info,
- CLONE_PARENT | SIGCHLD);
- if (pid < 0) {
- sub_info->retval = pid;
- umh_complete(sub_info);
- }
- }
-}
-
-/*
- * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY
- * (used for preventing user land processes from being created after the user
- * land has been frozen during a system-wide hibernation or suspend operation).
- * Should always be manipulated under umhelper_sem acquired for write.
- */
-static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED;
-
-/* Number of helpers running */
-static atomic_t running_helpers = ATOMIC_INIT(0);
-
-/*
- * Wait queue head used by usermodehelper_disable() to wait for all running
- * helpers to finish.
- */
-static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq);
-
-/*
- * Used by usermodehelper_read_lock_wait() to wait for usermodehelper_disabled
- * to become 'false'.
- */
-static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq);
-
-/*
- * Time to wait for running_helpers to become zero before the setting of
- * usermodehelper_disabled in usermodehelper_disable() fails
- */
-#define RUNNING_HELPERS_TIMEOUT (5 * HZ)
-
-int usermodehelper_read_trylock(void)
-{
- DEFINE_WAIT(wait);
- int ret = 0;
-
- down_read(&umhelper_sem);
- for (;;) {
- prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
- TASK_INTERRUPTIBLE);
- if (!usermodehelper_disabled)
- break;
-
- if (usermodehelper_disabled == UMH_DISABLED)
- ret = -EAGAIN;
-
- up_read(&umhelper_sem);
-
- if (ret)
- break;
-
- schedule();
- try_to_freeze();
-
- down_read(&umhelper_sem);
- }
- finish_wait(&usermodehelper_disabled_waitq, &wait);
- return ret;
-}
-EXPORT_SYMBOL_GPL(usermodehelper_read_trylock);
-
-long usermodehelper_read_lock_wait(long timeout)
-{
- DEFINE_WAIT(wait);
-
- if (timeout < 0)
- return -EINVAL;
-
- down_read(&umhelper_sem);
- for (;;) {
- prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
- TASK_UNINTERRUPTIBLE);
- if (!usermodehelper_disabled)
- break;
-
- up_read(&umhelper_sem);
-
- timeout = schedule_timeout(timeout);
- if (!timeout)
- break;
-
- down_read(&umhelper_sem);
- }
- finish_wait(&usermodehelper_disabled_waitq, &wait);
- return timeout;
-}
-EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait);
-
-void usermodehelper_read_unlock(void)
-{
- up_read(&umhelper_sem);
-}
-EXPORT_SYMBOL_GPL(usermodehelper_read_unlock);
-
-/**
- * __usermodehelper_set_disable_depth - Modify usermodehelper_disabled.
- * @depth: New value to assign to usermodehelper_disabled.
- *
- * Change the value of usermodehelper_disabled (under umhelper_sem locked for
- * writing) and wakeup tasks waiting for it to change.
- */
-void __usermodehelper_set_disable_depth(enum umh_disable_depth depth)
-{
- down_write(&umhelper_sem);
- usermodehelper_disabled = depth;
- wake_up(&usermodehelper_disabled_waitq);
- up_write(&umhelper_sem);
-}
-
-/**
- * __usermodehelper_disable - Prevent new helpers from being started.
- * @depth: New value to assign to usermodehelper_disabled.
- *
- * Set usermodehelper_disabled to @depth and wait for running helpers to exit.
- */
-int __usermodehelper_disable(enum umh_disable_depth depth)
-{
- long retval;
-
- if (!depth)
- return -EINVAL;
-
- down_write(&umhelper_sem);
- usermodehelper_disabled = depth;
- up_write(&umhelper_sem);
-
- /*
- * From now on call_usermodehelper_exec() won't start any new
- * helpers, so it is sufficient if running_helpers turns out to
- * be zero at one point (it may be increased later, but that
- * doesn't matter).
- */
- retval = wait_event_timeout(running_helpers_waitq,
- atomic_read(&running_helpers) == 0,
- RUNNING_HELPERS_TIMEOUT);
- if (retval)
- return 0;
-
- __usermodehelper_set_disable_depth(UMH_ENABLED);
- return -EAGAIN;
-}
-
-static void helper_lock(void)
-{
- atomic_inc(&running_helpers);
- smp_mb__after_atomic();
-}
-
-static void helper_unlock(void)
-{
- if (atomic_dec_and_test(&running_helpers))
- wake_up(&running_helpers_waitq);
-}
-
-/**
- * call_usermodehelper_setup - prepare to call a usermode helper
- * @path: path to usermode executable
- * @argv: arg vector for process
- * @envp: environment for process
- * @gfp_mask: gfp mask for memory allocation
- * @cleanup: a cleanup function
- * @init: an init function
- * @data: arbitrary context sensitive data
- *
- * Returns either %NULL on allocation failure, or a subprocess_info
- * structure. This should be passed to call_usermodehelper_exec to
- * exec the process and free the structure.
- *
- * The init function is used to customize the helper process prior to
- * exec. A non-zero return code causes the process to error out, exit,
- * and return the failure to the calling process
- *
- * The cleanup function is just before ethe subprocess_info is about to
- * be freed. This can be used for freeing the argv and envp. The
- * Function must be runnable in either a process context or the
- * context in which call_usermodehelper_exec is called.
- */
-struct subprocess_info *call_usermodehelper_setup(const char *path, char **argv,
- char **envp, gfp_t gfp_mask,
- int (*init)(struct subprocess_info *info, struct cred *new),
- void (*cleanup)(struct subprocess_info *info),
- void *data)
-{
- struct subprocess_info *sub_info;
- sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask);
- if (!sub_info)
- goto out;
-
- INIT_WORK(&sub_info->work, call_usermodehelper_exec_work);
-
-#ifdef CONFIG_STATIC_USERMODEHELPER
- sub_info->path = CONFIG_STATIC_USERMODEHELPER_PATH;
-#else
- sub_info->path = path;
-#endif
- sub_info->argv = argv;
- sub_info->envp = envp;
-
- sub_info->cleanup = cleanup;
- sub_info->init = init;
- sub_info->data = data;
- out:
- return sub_info;
-}
-EXPORT_SYMBOL(call_usermodehelper_setup);
-
-/**
- * call_usermodehelper_exec - start a usermode application
- * @sub_info: information about the subprocessa
- * @wait: wait for the application to finish and return status.
- * when UMH_NO_WAIT don't wait at all, but you get no useful error back
- * when the program couldn't be exec'ed. This makes it safe to call
- * from interrupt context.
- *
- * Runs a user-space application. The application is started
- * asynchronously if wait is not set, and runs as a child of system workqueues.
- * (ie. it runs with full root capabilities and optimized affinity).
- */
-int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
-{
- DECLARE_COMPLETION_ONSTACK(done);
- int retval = 0;
-
- if (!sub_info->path) {
- call_usermodehelper_freeinfo(sub_info);
- return -EINVAL;
- }
- helper_lock();
- if (usermodehelper_disabled) {
- retval = -EBUSY;
- goto out;
- }
-
- /*
- * If there is no binary for us to call, then just return and get out of
- * here. This allows us to set STATIC_USERMODEHELPER_PATH to "" and
- * disable all call_usermodehelper() calls.
- */
- if (strlen(sub_info->path) == 0)
- goto out;
-
- /*
- * Set the completion pointer only if there is a waiter.
- * This makes it possible to use umh_complete to free
- * the data structure in case of UMH_NO_WAIT.
- */
- sub_info->complete = (wait == UMH_NO_WAIT) ? NULL : &done;
- sub_info->wait = wait;
-
- queue_work(system_unbound_wq, &sub_info->work);
- if (wait == UMH_NO_WAIT) /* task has freed sub_info */
- goto unlock;
-
- if (wait & UMH_KILLABLE) {
- retval = wait_for_completion_killable(&done);
- if (!retval)
- goto wait_done;
-
- /* umh_complete() will see NULL and free sub_info */
- if (xchg(&sub_info->complete, NULL))
- goto unlock;
- /* fallthrough, umh_complete() was already called */
- }
-
- wait_for_completion(&done);
-wait_done:
- retval = sub_info->retval;
-out:
- call_usermodehelper_freeinfo(sub_info);
-unlock:
- helper_unlock();
- return retval;
-}
-EXPORT_SYMBOL(call_usermodehelper_exec);
-
-/**
- * call_usermodehelper() - prepare and start a usermode application
- * @path: path to usermode executable
- * @argv: arg vector for process
- * @envp: environment for process
- * @wait: wait for the application to finish and return status.
- * when UMH_NO_WAIT don't wait at all, but you get no useful error back
- * when the program couldn't be exec'ed. This makes it safe to call
- * from interrupt context.
- *
- * This function is the equivalent to use call_usermodehelper_setup() and
- * call_usermodehelper_exec().
- */
-int call_usermodehelper(const char *path, char **argv, char **envp, int wait)
-{
- struct subprocess_info *info;
- gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
-
- info = call_usermodehelper_setup(path, argv, envp, gfp_mask,
- NULL, NULL, NULL);
- if (info == NULL)
- return -ENOMEM;
-
- return call_usermodehelper_exec(info, wait);
-}
-EXPORT_SYMBOL(call_usermodehelper);
-
-static int proc_cap_handler(struct ctl_table *table, int write,
- void __user *buffer, size_t *lenp, loff_t *ppos)
-{
- struct ctl_table t;
- unsigned long cap_array[_KERNEL_CAPABILITY_U32S];
- kernel_cap_t new_cap;
- int err, i;
-
- if (write && (!capable(CAP_SETPCAP) ||
- !capable(CAP_SYS_MODULE)))
- return -EPERM;
-
- /*
- * convert from the global kernel_cap_t to the ulong array to print to
- * userspace if this is a read.
- */
- spin_lock(&umh_sysctl_lock);
- for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++) {
- if (table->data == CAP_BSET)
- cap_array[i] = usermodehelper_bset.cap[i];
- else if (table->data == CAP_PI)
- cap_array[i] = usermodehelper_inheritable.cap[i];
- else
- BUG();
- }
- spin_unlock(&umh_sysctl_lock);
-
- t = *table;
- t.data = &cap_array;
-
- /*
- * actually read or write and array of ulongs from userspace. Remember
- * these are least significant 32 bits first
- */
- err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos);
- if (err < 0)
- return err;
-
- /*
- * convert from the sysctl array of ulongs to the kernel_cap_t
- * internal representation
- */
- for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++)
- new_cap.cap[i] = cap_array[i];
-
- /*
- * Drop everything not in the new_cap (but don't add things)
- */
- spin_lock(&umh_sysctl_lock);
- if (write) {
- if (table->data == CAP_BSET)
- usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap);
- if (table->data == CAP_PI)
- usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap);
- }
- spin_unlock(&umh_sysctl_lock);
-
- return 0;
-}
-
-struct ctl_table usermodehelper_table[] = {
- {
- .procname = "bset",
- .data = CAP_BSET,
- .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
- .mode = 0600,
- .proc_handler = proc_cap_handler,
- },
- {
- .procname = "inheritable",
- .data = CAP_PI,
- .maxlen = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
- .mode = 0600,
- .proc_handler = proc_cap_handler,
- },
- { }
-};
git.samba.org / sfrench / cifs-2.6.git / blobdiff