call_usermodehelper wait flag, and remove exec_usermodehelper.
Rusty Russell <rusty@rustcorp.com.au> Jan 2003
*/
-#define __KERNEL_SYSCALLS__
-
#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/fdtable.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 <linux/notifier.h>
+#include <linux/suspend.h>
#include <asm/uaccess.h>
+#include <trace/events/module.h>
+
extern int max_threads;
static struct workqueue_struct *khelper_wq;
-#ifdef CONFIG_KMOD
+#ifdef CONFIG_MODULES
/*
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
+ * __request_module - try to load a kernel module
+ * @wait: wait (or not) for the operation to complete
+ * @fmt: printf style format string for the name of the module
+ * @...: arguments 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
* If module auto-loading support is disabled then this function
* becomes a no-operation.
*/
-int request_module(const char *fmt, ...)
+int __request_module(bool wait, const char *fmt, ...)
{
va_list args;
char module_name[MODULE_NAME_LEN];
if (ret >= MODULE_NAME_LEN)
return -ENAMETOOLONG;
+ ret = security_kernel_module_request(module_name);
+ if (ret)
+ return ret;
+
/* 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
return -ENOMEM;
}
- ret = call_usermodehelper(modprobe_path, argv, envp, 1);
+ trace_module_request(module_name, wait, _RET_IP_);
+
+ ret = call_usermodehelper(modprobe_path, argv, envp,
+ wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
atomic_dec(&kmod_concurrent);
return ret;
}
-EXPORT_SYMBOL(request_module);
-#endif /* CONFIG_KMOD */
+EXPORT_SYMBOL(__request_module);
+#endif /* CONFIG_MODULES */
struct subprocess_info {
+ struct work_struct work;
struct completion *complete;
+ struct cred *cred;
char *path;
char **argv;
char **envp;
- struct key *ring;
- int wait;
+ enum umh_wait wait;
int retval;
+ struct file *stdin;
+ void (*cleanup)(char **argv, char **envp);
};
/*
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);
+ BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
+
+ /* Unblock all signals */
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 the credentials */
+ commit_creds(sub_info->cred);
+ sub_info->cred = NULL;
+
+ /* 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);
+ set_cpus_allowed_ptr(current, cpu_all_mask);
+
+ /*
+ * Our parent is keventd, which runs with elevated scheduling priority.
+ * Avoid propagating that into the userspace child.
+ */
+ set_user_nice(current, 0);
- retval = -EPERM;
- if (current->fs->root)
- retval = execve(sub_info->path, sub_info->argv,sub_info->envp);
+ retval = kernel_execve(sub_info->path, sub_info->argv, sub_info->envp);
/* Exec failed? */
sub_info->retval = retval;
do_exit(0);
}
+void call_usermodehelper_freeinfo(struct subprocess_info *info)
+{
+ if (info->cleanup)
+ (*info->cleanup)(info->argv, info->envp);
+ if (info->cred)
+ put_cred(info->cred);
+ kfree(info);
+}
+EXPORT_SYMBOL(call_usermodehelper_freeinfo);
+
/* 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.
*
* Thus the __user pointer cast is valid here.
*/
- sys_wait4(pid, (int __user *) &sub_info->retval, 0, NULL);
+ 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);
+ if (sub_info->wait == UMH_NO_WAIT)
+ call_usermodehelper_freeinfo(sub_info);
+ else
+ complete(sub_info->complete);
return 0;
}
/* This is run by khelper thread */
-static void __call_usermodehelper(void *data)
+static void __call_usermodehelper(struct work_struct *work)
{
- struct subprocess_info *sub_info = data;
+ struct subprocess_info *sub_info =
+ container_of(work, struct subprocess_info, work);
pid_t pid;
+ enum umh_wait wait = sub_info->wait;
+
+ BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
/* CLONE_VFORK: wait until the usermode helper has execve'd
* successfully We need the data structures to stay around
* until that is done. */
- if (sub_info->wait)
+ if (wait == UMH_WAIT_PROC || wait == UMH_NO_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) {
+ switch (wait) {
+ case UMH_NO_WAIT:
+ break;
+
+ case UMH_WAIT_PROC:
+ if (pid > 0)
+ break;
sub_info->retval = pid;
+ /* FALLTHROUGH */
+
+ case UMH_WAIT_EXEC:
complete(sub_info->complete);
- } else if (!sub_info->wait)
- complete(sub_info->complete);
+ }
+}
+
+#ifdef CONFIG_PM_SLEEP
+/*
+ * 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).
+ */
+static int usermodehelper_disabled;
+
+/* Number of helpers running */
+static atomic_t running_helpers = ATOMIC_INIT(0);
+
+/*
+ * Wait queue head used by usermodehelper_pm_callback() to wait for all running
+ * helpers to finish.
+ */
+static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq);
+
+/*
+ * Time to wait for running_helpers to become zero before the setting of
+ * usermodehelper_disabled in usermodehelper_pm_callback() fails
+ */
+#define RUNNING_HELPERS_TIMEOUT (5 * HZ)
+
+/**
+ * usermodehelper_disable - prevent new helpers from being started
+ */
+int usermodehelper_disable(void)
+{
+ long retval;
+
+ usermodehelper_disabled = 1;
+ smp_mb();
+ /*
+ * 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_disabled = 0;
+ return -EAGAIN;
+}
+
+/**
+ * usermodehelper_enable - allow new helpers to be started again
+ */
+void usermodehelper_enable(void)
+{
+ usermodehelper_disabled = 0;
+}
+
+static void helper_lock(void)
+{
+ atomic_inc(&running_helpers);
+ smp_mb__after_atomic_inc();
+}
+
+static void helper_unlock(void)
+{
+ if (atomic_dec_and_test(&running_helpers))
+ wake_up(&running_helpers_waitq);
}
+#else /* CONFIG_PM_SLEEP */
+#define usermodehelper_disabled 0
+
+static inline void helper_lock(void) {}
+static inline void helper_unlock(void) {}
+#endif /* CONFIG_PM_SLEEP */
+
+/**
+ * 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
+ *
+ * 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.
+ */
+struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
+ char **envp, gfp_t gfp_mask)
+{
+ 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);
+ sub_info->path = path;
+ sub_info->argv = argv;
+ sub_info->envp = envp;
+ sub_info->cred = prepare_usermodehelper_creds();
+ if (!sub_info->cred) {
+ kfree(sub_info);
+ return NULL;
+ }
+
+ out:
+ return sub_info;
+}
+EXPORT_SYMBOL(call_usermodehelper_setup);
+
+/**
+ * call_usermodehelper_setkeys - set the session keys for usermode helper
+ * @info: a subprocess_info returned by call_usermodehelper_setup
+ * @session_keyring: the session keyring for the process
+ */
+void call_usermodehelper_setkeys(struct subprocess_info *info,
+ struct key *session_keyring)
+{
+#ifdef CONFIG_KEYS
+ struct thread_group_cred *tgcred = info->cred->tgcred;
+ key_put(tgcred->session_keyring);
+ tgcred->session_keyring = key_get(session_keyring);
+#else
+ BUG();
+#endif
+}
+EXPORT_SYMBOL(call_usermodehelper_setkeys);
/**
- * 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)
+ * call_usermodehelper_setcleanup - set a cleanup function
+ * @info: a subprocess_info returned by call_usermodehelper_setup
+ * @cleanup: a cleanup function
+ *
+ * The cleanup function is just befor 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.
+ */
+void call_usermodehelper_setcleanup(struct subprocess_info *info,
+ void (*cleanup)(char **argv, char **envp))
+{
+ info->cleanup = cleanup;
+}
+EXPORT_SYMBOL(call_usermodehelper_setcleanup);
+
+/**
+ * call_usermodehelper_stdinpipe - set up a pipe to be used for stdin
+ * @sub_info: a subprocess_info returned by call_usermodehelper_setup
+ * @filp: set to the write-end of a pipe
+ *
+ * This constructs a pipe, and sets the read end to be the stdin of the
+ * subprocess, and returns the write-end in *@filp.
+ */
+int call_usermodehelper_stdinpipe(struct subprocess_info *sub_info,
+ struct file **filp)
+{
+ struct file *f;
+
+ f = create_write_pipe(0);
+ if (IS_ERR(f))
+ return PTR_ERR(f);
+ *filp = f;
+
+ f = create_read_pipe(f, 0);
+ if (IS_ERR(f)) {
+ free_write_pipe(*filp);
+ return PTR_ERR(f);
+ }
+ sub_info->stdin = f;
+
+ return 0;
+}
+EXPORT_SYMBOL(call_usermodehelper_stdinpipe);
+
+/**
+ * call_usermodehelper_exec - start a usermode application
+ * @sub_info: information about the subprocessa
* @wait: wait for the application to finish and return status.
+ * when -1 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 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)
+int call_usermodehelper_exec(struct subprocess_info *sub_info,
+ enum umh_wait wait)
{
- DECLARE_COMPLETION(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;
+ DECLARE_COMPLETION_ONSTACK(done);
+ int retval = 0;
+
+ BUG_ON(atomic_read(&sub_info->cred->usage) != 1);
+ validate_creds(sub_info->cred);
- queue_work(khelper_wq, &work);
+ helper_lock();
+ if (sub_info->path[0] == '\0')
+ goto out;
+
+ if (!khelper_wq || usermodehelper_disabled) {
+ retval = -EBUSY;
+ goto out;
+ }
+
+ sub_info->complete = &done;
+ sub_info->wait = wait;
+
+ queue_work(khelper_wq, &sub_info->work);
+ if (wait == UMH_NO_WAIT) /* task has freed sub_info */
+ goto unlock;
wait_for_completion(&done);
- return sub_info.retval;
+ retval = sub_info->retval;
+
+out:
+ call_usermodehelper_freeinfo(sub_info);
+unlock:
+ helper_unlock();
+ return retval;
+}
+EXPORT_SYMBOL(call_usermodehelper_exec);
+
+/**
+ * call_usermodehelper_pipe - call a usermode helper process with a pipe stdin
+ * @path: path to usermode executable
+ * @argv: arg vector for process
+ * @envp: environment for process
+ * @filp: set to the write-end of a pipe
+ *
+ * This is a simple wrapper which executes a usermode-helper function
+ * with a pipe as stdin. It is implemented entirely in terms of
+ * lower-level call_usermodehelper_* functions.
+ */
+int call_usermodehelper_pipe(char *path, char **argv, char **envp,
+ struct file **filp)
+{
+ struct subprocess_info *sub_info;
+ int ret;
+
+ sub_info = call_usermodehelper_setup(path, argv, envp, GFP_KERNEL);
+ if (sub_info == NULL)
+ return -ENOMEM;
+
+ ret = call_usermodehelper_stdinpipe(sub_info, filp);
+ if (ret < 0) {
+ call_usermodehelper_freeinfo(sub_info);
+ return ret;
+ }
+
+ ret = call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC);
+ if (ret < 0) /* Failed to execute helper, close pipe */
+ filp_close(*filp, NULL);
+
+ return ret;
}
-EXPORT_SYMBOL(call_usermodehelper_keys);
+EXPORT_SYMBOL(call_usermodehelper_pipe);
void __init usermodehelper_init(void)
{
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff