#include <linux/kmod.h>
#include <linux/slab.h>
#include <linux/completion.h>
+#include <linux/cred.h>
#include <linux/file.h>
#include <linux/fdtable.h>
#include <linux/workqueue.h>
#include <linux/resource.h>
#include <linux/notifier.h>
#include <linux/suspend.h>
+#include <linux/rwsem.h>
#include <asm/uaccess.h>
#include <trace/events/module.h>
static struct workqueue_struct *khelper_wq;
+#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
/*
*/
char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
+static void free_modprobe_argv(struct subprocess_info *info)
+{
+ kfree(info->argv[3]); /* check call_modprobe() */
+ kfree(info->argv);
+}
+
+static int call_modprobe(char *module_name, int wait)
+{
+ static char *envp[] = {
+ "HOME=/",
+ "TERM=linux",
+ "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
+ NULL
+ };
+
+ char **argv = kmalloc(sizeof(char *[5]), GFP_KERNEL);
+ if (!argv)
+ goto out;
+
+ module_name = kstrdup(module_name, GFP_KERNEL);
+ if (!module_name)
+ goto free_argv;
+
+ argv[0] = modprobe_path;
+ argv[1] = "-q";
+ argv[2] = "--";
+ argv[3] = module_name; /* check free_modprobe_argv() */
+ argv[4] = NULL;
+
+ return call_usermodehelper_fns(modprobe_path, argv, envp,
+ wait | UMH_KILLABLE, NULL, free_modprobe_argv, NULL);
+free_argv:
+ kfree(argv);
+out:
+ return -ENOMEM;
+}
+
/**
* __request_module - try to load a kernel module
* @wait: wait (or not) for the operation to complete
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;
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)
+ if (kmod_loop_msg < 5) {
printk(KERN_ERR
"request_module: runaway loop modprobe %s\n",
module_name);
+ kmod_loop_msg++;
+ }
atomic_dec(&kmod_concurrent);
return -ENOMEM;
}
trace_module_request(module_name, wait, _RET_IP_);
- ret = call_usermodehelper_fns(modprobe_path, argv, envp,
- wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC,
- NULL, NULL, NULL);
+ ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
atomic_dec(&kmod_concurrent);
return ret;
static int ____call_usermodehelper(void *data)
{
struct subprocess_info *sub_info = data;
+ struct cred *new;
int retval;
spin_lock_irq(¤t->sighand->siglock);
*/
set_user_nice(current, 0);
+ retval = -ENOMEM;
+ new = prepare_kernel_cred(current);
+ if (!new)
+ goto fail;
+
+ 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);
- if (retval)
+ retval = sub_info->init(sub_info, new);
+ if (retval) {
+ abort_creds(new);
goto fail;
+ }
}
- retval = kernel_execve(sub_info->path, sub_info->argv, sub_info->envp);
+ commit_creds(new);
+
+ retval = kernel_execve(sub_info->path,
+ (const char *const *)sub_info->argv,
+ (const char *const *)sub_info->envp);
/* Exec failed? */
fail:
sub_info->retval = retval;
- do_exit(0);
+ return 0;
}
void call_usermodehelper_freeinfo(struct subprocess_info *info)
}
EXPORT_SYMBOL(call_usermodehelper_freeinfo);
+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.
+ */
+ if (comp)
+ complete(comp);
+ else
+ call_usermodehelper_freeinfo(sub_info);
+}
+
/* 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;
- /* Install a handler: if SIGCLD isn't handled sys_wait4 won't
- * populate the status, but will return -ECHILD. */
- allow_signal(SIGCHLD);
+ /* If SIGCLD is ignored sys_wait4 won't populate the status. */
+ spin_lock_irq(¤t->sighand->siglock);
+ current->sighand->action[SIGCHLD-1].sa.sa_handler = SIG_DFL;
+ spin_unlock_irq(¤t->sighand->siglock);
pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD);
if (pid < 0) {
sub_info->retval = pid;
} else {
- int ret;
-
+ 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.
sub_info->retval = ret;
}
- if (sub_info->wait == UMH_NO_WAIT)
- call_usermodehelper_freeinfo(sub_info);
- else
- complete(sub_info->complete);
+ umh_complete(sub_info);
return 0;
}
{
struct subprocess_info *sub_info =
container_of(work, struct subprocess_info, work);
+ int wait = sub_info->wait & ~UMH_KILLABLE;
pid_t pid;
- enum umh_wait 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 == UMH_WAIT_PROC || wait == UMH_NO_WAIT)
+ if (wait == UMH_WAIT_PROC)
pid = kernel_thread(wait_for_helper, sub_info,
CLONE_FS | CLONE_FILES | SIGCHLD);
else
switch (wait) {
case UMH_NO_WAIT:
+ call_usermodehelper_freeinfo(sub_info);
break;
case UMH_WAIT_PROC:
if (pid > 0)
break;
- sub_info->retval = pid;
/* FALLTHROUGH */
-
case UMH_WAIT_EXEC:
- complete(sub_info->complete);
+ if (pid < 0)
+ sub_info->retval = pid;
+ umh_complete(sub_info);
}
}
-#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).
+ * Should always be manipulated under umhelper_sem acquired for write.
*/
-static int usermodehelper_disabled;
+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_pm_callback() to wait for all running
+ * 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_pm_callback() fails
+ * 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
+ * __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(void)
+int __usermodehelper_disable(enum umh_disable_depth depth)
{
long retval;
- usermodehelper_disabled = 1;
- smp_mb();
+ 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
if (retval)
return 0;
- usermodehelper_disabled = 0;
+ __usermodehelper_set_disable_depth(UMH_ENABLED);
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);
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
* context in which call_usermodehelper_exec is called.
*/
void call_usermodehelper_setfns(struct subprocess_info *info,
- int (*init)(struct subprocess_info *info),
+ int (*init)(struct subprocess_info *info, struct cred *new),
void (*cleanup)(struct subprocess_info *info),
void *data)
{
* asynchronously if wait is not set, and runs as a child of keventd.
* (ie. it runs with full root capabilities).
*/
-int call_usermodehelper_exec(struct subprocess_info *sub_info,
- enum umh_wait wait)
+int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
{
DECLARE_COMPLETION_ONSTACK(done);
int retval = 0;
queue_work(khelper_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:
}
EXPORT_SYMBOL(call_usermodehelper_exec);
+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,
+ },
+ { }
+};
+
void __init usermodehelper_init(void)
{
khelper_wq = create_singlethread_workqueue("khelper");
projects / linux-flexiantxendom0-3.2.10.git / blobdiff