Commit c290649e authored by Rusty Russell's avatar Rusty Russell Committed by Linus Torvalds

[PATCH] get rid of exec_usermodehelper, replace with call_usermodehelper

Urban Widmark points out that modprobe calls system() in many
configurations, which drops privs since request_module() doesn't
set ruid and rguid.

This gets rid of exec_usermodehelper and makes everyone use
call_usermodehelper, which has a new "wait" flag.
parent 817f3eee
......@@ -57,7 +57,7 @@ voyager_thread_start(void)
}
static int
execute_helper(void *string)
execute(const char *string)
{
int ret;
......@@ -74,22 +74,13 @@ execute_helper(void *string)
NULL,
};
if((ret = exec_usermodehelper(argv[0], argv, envp)) < 0) {
printk(KERN_ERR "Voyager failed to execute \"%s\"\n",
(char *)string);
if ((ret = call_usermodehelper(argv[0], argv, envp, 1)) != 0) {
printk(KERN_ERR "Voyager failed to run \"%s\": %i\n",
string, ret);
}
return ret;
}
static void
execute(char *string)
{
if(kernel_thread(execute_helper, (void *)string, CLONE_VFORK | SIGCHLD) < 0) {
printk(KERN_ERR "Voyager failed to fork before exec of \"%s\"\n",
string);
}
}
static void
check_from_kernel(void)
{
......
......@@ -436,7 +436,7 @@ acpi_thermal_call_usermode (
envp[0] = "HOME=/";
envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
call_usermodehelper(argv[0], argv, envp);
call_usermodehelper(argv[0], argv, envp, 0);
return_VALUE(0);
}
......
......@@ -114,7 +114,7 @@ static int do_hotplug (struct device *dev, char *argv1, const char *action,
pr_debug ("%s: %s %s %s %s %s %s\n", __FUNCTION__, argv [0], argv[1],
envp[0], envp[1], envp[2], envp[3]);
retval = call_usermodehelper (argv [0], argv, envp);
retval = call_usermodehelper (argv [0], argv, envp, 0);
if (retval)
pr_debug ("%s - call_usermodehelper returned %d\n",
__FUNCTION__, retval);
......
......@@ -24,18 +24,14 @@
#include <linux/config.h>
#include <linux/module.h>
#define __KERNEL_SYSCALLS__
#include <linux/kernel.h>
#include <linux/kmod.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/timer.h>
#include <linux/errno.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/ioport.h>
#include <linux/spinlock.h>
......@@ -405,7 +401,6 @@ void bt3c_interrupt(int irq, void *dev_inst, struct pt_regs *regs)
/* ======================== HCI interface ======================== */
......@@ -489,65 +484,23 @@ static int bt3c_hci_ioctl(struct hci_dev *hdev, unsigned int cmd, unsigned long
#define FW_LOADER "/sbin/bluefw"
static int errno;
static int bt3c_fw_loader_exec(void *dev)
{
char *argv[] = { FW_LOADER, "pccard", dev, NULL };
char *envp[] = { "HOME=/", "TERM=linux", "PATH=/sbin:/usr/sbin:/bin:/usr/bin", NULL };
int err;
err = exec_usermodehelper(FW_LOADER, argv, envp);
if (err)
printk(KERN_WARNING "bt3c_cs: Failed to exec \"%s pccard %s\".\n", FW_LOADER, (char *)dev);
return err;
}
static int bt3c_firmware_load(bt3c_info_t *info)
{
sigset_t tmpsig;
char dev[16];
pid_t pid;
int result;
int err;
/* Check if root fs is mounted */
if (!current->fs->root) {
printk(KERN_WARNING "bt3c_cs: Root filesystem is not mounted.\n");
return -EPERM;
}
char *argv[] = { FW_LOADER, "pccard", dev, NULL };
char *envp[] = { "HOME=/", "TERM=linux", "PATH=/sbin:/usr/sbin:/bin:/usr/bin", NULL };
sprintf(dev, "%04x", info->link.io.BasePort1);
pid = kernel_thread(bt3c_fw_loader_exec, (void *)dev, 0);
if (pid < 0) {
printk(KERN_WARNING "bt3c_cs: Forking of kernel thread failed (errno=%d).\n", -pid);
return pid;
}
/* Block signals, everything but SIGKILL/SIGSTOP */
spin_lock_irq(&current->sighand->siglock);
tmpsig = current->blocked;
siginitsetinv(&current->blocked, sigmask(SIGKILL) | sigmask(SIGSTOP));
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
result = waitpid(pid, NULL, __WCLONE);
/* Allow signals again */
spin_lock_irq(&current->sighand->siglock);
current->blocked = tmpsig;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
if (result != pid) {
printk(KERN_WARNING "bt3c_cs: Waiting for pid %d failed (errno=%d).\n", pid, -result);
return -result;
}
err = call_usermodehelper(FW_LOADER, argv, envp, 1);
if (err)
printk(KERN_WARNING "bt3c_cs: Failed to run \"%s pccard %s\" (errno=%d).\n", FW_LOADER, dev, err);
return 0;
return err;
}
......
......@@ -786,7 +786,7 @@ static void nodemgr_call_policy(char *verb, struct unit_directory *ud)
#ifdef CONFIG_IEEE1394_VERBOSEDEBUG
HPSB_DEBUG("NodeMgr: %s %s %016Lx", argv[0], verb, (long long unsigned)ud->ne->guid);
#endif
value = call_usermodehelper(argv[0], argv, envp);
value = call_usermodehelper(argv[0], argv, envp, 0);
kfree(buf);
kfree(envp);
if (value != 0)
......
......@@ -383,7 +383,7 @@ static void input_call_hotplug(char *verb, struct input_dev *dev)
argv[0], argv[1], envp[0], envp[1], envp[2], envp[3], envp[4]);
#endif
value = call_usermodehelper(argv [0], argv, envp);
value = call_usermodehelper(argv [0], argv, envp, 0);
kfree(buf);
kfree(envp);
......
......@@ -263,7 +263,7 @@ static void diva_adapter_trapped(void *context)
pdpc->card_failed = 0;
argv[2] = &adapter[0];
ret = call_usermodehelper(argv[0], argv, envp);
ret = call_usermodehelper(argv[0], argv, envp, 0);
if (ret) {
printk(KERN_ERR
......
......@@ -369,15 +369,14 @@ static char eppconfig_path[256] = "/usr/sbin/eppfpga";
static char *envp[] = { "HOME=/", "TERM=linux", "PATH=/usr/bin:/bin", NULL };
static int errno;
static int exec_eppfpga(void *b)
/* eppconfig: called during ifconfig up to configure the modem */
static int eppconfig(struct baycom_state *bc)
{
struct baycom_state *bc = (struct baycom_state *)b;
char modearg[256];
char portarg[16];
char *argv[] = { eppconfig_path, "-s", "-p", portarg, "-m", modearg, NULL};
int i;
char *argv[] = { eppconfig_path, "-s", "-p", portarg, "-m", modearg,
NULL };
int ret;
/* set up arguments */
sprintf(modearg, "%sclk,%smodem,fclk=%d,bps=%d,divider=%d%s,extstat",
......@@ -388,39 +387,7 @@ static int exec_eppfpga(void *b)
sprintf(portarg, "%ld", bc->pdev->port->base);
printk(KERN_DEBUG "%s: %s -s -p %s -m %s\n", bc_drvname, eppconfig_path, portarg, modearg);
i = exec_usermodehelper(eppconfig_path, argv, envp);
if (i < 0) {
printk(KERN_ERR "%s: failed to exec %s -s -p %s -m %s, errno = %d\n",
bc_drvname, eppconfig_path, portarg, modearg, i);
return i;
}
return 0;
}
/* eppconfig: called during ifconfig up to configure the modem */
static int eppconfig(struct baycom_state *bc)
{
int i, pid, r;
mm_segment_t fs;
pid = kernel_thread(exec_eppfpga, bc, CLONE_FS);
if (pid < 0) {
printk(KERN_ERR "%s: fork failed, errno %d\n", bc_drvname, -pid);
return pid;
}
fs = get_fs();
set_fs(KERNEL_DS); /* Allow i to be in kernel space. */
r = waitpid(pid, &i, __WCLONE);
set_fs(fs);
if (r != pid) {
printk(KERN_ERR "%s: waitpid(%d) failed, returning %d\n",
bc_drvname, pid, r);
return -1;
}
printk(KERN_DEBUG "%s: eppfpga returned %d\n", bc_drvname, i);
return i;
return call_usermodehelper(eppconfig_path, argv, envp, 1);
}
/* ---------------------------------------------------------------------- */
......
......@@ -602,7 +602,7 @@ static int pnp_dock_event(int dock, struct pnp_docking_station_info *info)
info->location_id, info->serial, info->capabilities);
envp[i] = 0;
value = call_usermodehelper (argv [0], argv, envp);
value = call_usermodehelper (argv [0], argv, envp, 0);
kfree (buf);
kfree (envp);
return 0;
......
......@@ -21,6 +21,7 @@
#include <linux/config.h>
#include <linux/errno.h>
#include <linux/compiler.h>
#ifdef CONFIG_KMOD
extern int request_module(const char * name);
......@@ -29,8 +30,7 @@ static inline int request_module(const char * name) { return -ENOSYS; }
#endif
#define try_then_request_module(x, mod) ((x) ?: request_module(mod), (x))
extern int exec_usermodehelper(char *program_path, char *argv[], char *envp[]);
extern int call_usermodehelper(char *path, char *argv[], char *envp[]);
extern int call_usermodehelper(char *path, char *argv[], char *envp[], int wait);
#ifdef CONFIG_HOTPLUG
extern char hotplug_path [];
......
......@@ -14,8 +14,10 @@
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
*/
#define __KERNEL_SYSCALLS__
#include <linux/config.h>
......@@ -31,112 +33,11 @@
#include <linux/workqueue.h>
#include <linux/security.h>
#include <linux/mount.h>
#include <linux/kernel.h>
#include <asm/uaccess.h>
extern int max_threads, system_running;
static inline void
use_init_fs_context(void)
{
struct fs_struct *our_fs, *init_fs;
struct dentry *root, *pwd;
struct vfsmount *rootmnt, *pwdmnt;
struct namespace *our_ns, *init_ns;
/*
* Make modprobe's fs context be a copy of init's.
*
* We cannot use the user's fs context, because it
* may have a different root than init.
* Since init was created with CLONE_FS, we can grab
* its fs context from "init_task".
*
* The fs context has to be a copy. If it is shared
* with init, then any chdir() call in modprobe will
* also affect init and the other threads sharing
* init_task's fs context.
*
* We created the exec_modprobe thread without CLONE_FS,
* so we can update the fields in our fs context freely.
*/
init_fs = init_task.fs;
init_ns = init_task.namespace;
get_namespace(init_ns);
our_ns = current->namespace;
current->namespace = init_ns;
put_namespace(our_ns);
read_lock(&init_fs->lock);
rootmnt = mntget(init_fs->rootmnt);
root = dget(init_fs->root);
pwdmnt = mntget(init_fs->pwdmnt);
pwd = dget(init_fs->pwd);
read_unlock(&init_fs->lock);
/* FIXME - unsafe ->fs access */
our_fs = current->fs;
our_fs->umask = init_fs->umask;
set_fs_root(our_fs, rootmnt, root);
set_fs_pwd(our_fs, pwdmnt, pwd);
write_lock(&our_fs->lock);
if (our_fs->altroot) {
struct vfsmount *mnt = our_fs->altrootmnt;
struct dentry *dentry = our_fs->altroot;
our_fs->altrootmnt = NULL;
our_fs->altroot = NULL;
write_unlock(&our_fs->lock);
dput(dentry);
mntput(mnt);
} else
write_unlock(&our_fs->lock);
dput(root);
mntput(rootmnt);
dput(pwd);
mntput(pwdmnt);
}
int exec_usermodehelper(char *program_path, char *argv[], char *envp[])
{
int i;
struct task_struct *curtask = current;
set_special_pids(1, 1);
use_init_fs_context();
/* Prevent parent user process from sending signals to child.
Otherwise, if the modprobe program does not exist, it might
be possible to get a user defined signal handler to execute
as the super user right after the execve fails if you time
the signal just right.
*/
flush_signals(curtask);
flush_signal_handlers(curtask);
spin_lock_irq(&curtask->sighand->siglock);
sigemptyset(&curtask->blocked);
recalc_sigpending();
spin_unlock_irq(&curtask->sighand->siglock);
for (i = 0; i < curtask->files->max_fds; i++ ) {
if (curtask->files->fd[i]) close(i);
}
switch_uid(INIT_USER);
/* Give kmod all effective privileges.. */
curtask->euid = curtask->fsuid = 0;
curtask->egid = curtask->fsgid = 0;
security_task_kmod_set_label();
/* Allow execve args to be in kernel space. */
set_fs(KERNEL_DS);
/* Go, go, go... */
if (execve(program_path, argv, envp) < 0)
return -errno;
return 0;
}
#ifdef CONFIG_KMOD
/*
......@@ -144,29 +45,6 @@ int exec_usermodehelper(char *program_path, char *argv[], char *envp[])
*/
char modprobe_path[256] = "/sbin/modprobe";
static int exec_modprobe(void * module_name)
{
static char * envp[] = { "HOME=/", "TERM=linux", "PATH=/sbin:/usr/sbin:/bin:/usr/bin", NULL };
char *argv[] = { modprobe_path, "--", (char*)module_name, NULL };
int ret;
if (!system_running)
return -EBUSY;
ret = exec_usermodehelper(modprobe_path, argv, envp);
if (ret) {
static unsigned long last;
unsigned long now = jiffies;
if (now - last > HZ) {
last = now;
printk(KERN_DEBUG
"kmod: failed to exec %s -s -k %s, errno = %d\n",
modprobe_path, (char*) module_name, errno);
}
}
return ret;
}
/**
* request_module - try to load a kernel module
* @module_name: Name of module
......@@ -180,24 +58,18 @@ static int exec_modprobe(void * module_name)
* If module auto-loading support is disabled then this function
* becomes a no-operation.
*/
int request_module(const char * module_name)
int request_module(const char *module_name)
{
pid_t pid;
int waitpid_result;
sigset_t tmpsig;
int i, ret;
unsigned int max_modprobes;
int ret;
char *argv[] = { modprobe_path, "--", (char*)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;
unsigned long saved_policy = current->policy;
current->policy = SCHED_NORMAL;
/* Don't allow request_module() when the system isn't set up */
if ( ! system_running ) {
printk(KERN_ERR "request_module[%s]: not ready\n", module_name);
ret = -EPERM;
goto out;
}
/* 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
......@@ -207,61 +79,44 @@ int request_module(const char * module_name)
* 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
*/
i = max_threads/2;
if (i > MAX_KMOD_CONCURRENT)
i = MAX_KMOD_CONCURRENT;
max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT);
atomic_inc(&kmod_concurrent);
if (atomic_read(&kmod_concurrent) > i) {
if (atomic_read(&kmod_concurrent) > max_modprobes) {
/* We may be blaming an innocent here, but unlikely */
if (kmod_loop_msg++ < 5)
printk(KERN_ERR
"kmod: runaway modprobe loop assumed and stopped\n");
"request_module: runaway loop modprobe %s\n",
module_name);
atomic_dec(&kmod_concurrent);
ret = -ENOMEM;
goto out;
return -ENOMEM;
}
pid = kernel_thread(exec_modprobe, (void*) module_name, 0);
if (pid < 0) {
printk(KERN_ERR "request_module[%s]: fork failed, errno %d\n", module_name, -pid);
atomic_dec(&kmod_concurrent);
ret = pid;
goto out;
ret = call_usermodehelper(modprobe_path, argv, envp, 1);
if (ret != 0) {
static unsigned long last;
unsigned long now = jiffies;
if (now - last > HZ) {
last = now;
printk(KERN_DEBUG
"request_module: failed %s -- %s. error = %d\n",
modprobe_path, module_name, ret);
}
}
/* Block everything but SIGKILL/SIGSTOP */
spin_lock_irq(&current->sighand->siglock);
tmpsig = current->blocked;
siginitsetinv(&current->blocked, sigmask(SIGKILL) | sigmask(SIGSTOP));
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
waitpid_result = waitpid(pid, NULL, __WCLONE);
atomic_dec(&kmod_concurrent);
/* Allow signals again.. */
spin_lock_irq(&current->sighand->siglock);
current->blocked = tmpsig;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
if (waitpid_result != pid) {
printk(KERN_ERR "request_module[%s]: waitpid(%d,...) failed, errno %d\n",
module_name, pid, -waitpid_result);
}
ret = 0;
out:
current->policy = saved_policy;
return ret;
}
#endif /* CONFIG_KMOD */
#ifdef CONFIG_HOTPLUG
/*
hotplug path is set via /proc/sys
invoked by hotplug-aware bus drivers,
with exec_usermodehelper and some thread-spawner
with call_usermodehelper
argv [0] = hotplug_path;
argv [1] = "usb", "scsi", "pci", "network", etc;
......@@ -285,7 +140,8 @@ struct subprocess_info {
char *path;
char **argv;
char **envp;
pid_t retval;
int wait;
int retval;
};
/*
......@@ -298,13 +154,30 @@ static int ____call_usermodehelper(void *data)
retval = -EPERM;
if (current->fs->root)
retval = exec_usermodehelper(sub_info->path, sub_info->argv, sub_info->envp);
retval = execve(sub_info->path, sub_info->argv,sub_info->envp);
/* Exec failed? */
sub_info->retval = (pid_t)retval;
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;
pid = kernel_thread(____call_usermodehelper, sub_info,
CLONE_VFORK | SIGCHLD);
if (pid < 0)
sub_info->retval = pid;
else
sys_wait4(pid, (unsigned int *)&sub_info->retval, 0, NULL);
complete(sub_info->complete);
return 0;
}
/*
* This is run by keventd.
*/
......@@ -313,14 +186,21 @@ static void __call_usermodehelper(void *data)
struct subprocess_info *sub_info = data;
pid_t pid;
/*
* CLONE_VFORK: wait until the usermode helper has execve'd successfully
* We need the data structures to stay around until that is done.
*/
pid = kernel_thread(____call_usermodehelper, sub_info, CLONE_VFORK | SIGCHLD);
if (pid < 0)
/* 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)
pid = kernel_thread(wait_for_helper, sub_info,
CLONE_KERNEL | SIGCHLD);
else
pid = kernel_thread(____call_usermodehelper, sub_info,
CLONE_VFORK | SIGCHLD);
if (pid < 0) {
sub_info->retval = pid;
complete(sub_info->complete);
complete(sub_info->complete);
} else if (!sub_info->wait)
complete(sub_info->complete);
}
/**
......@@ -328,15 +208,17 @@ static void __call_usermodehelper(void *data)
* @path: pathname for the application
* @argv: null-terminated argument list
* @envp: null-terminated environment list
* @wait: wait for the application to finish and return status.
*
* Runs a user-space application. The application is started asynchronously. It
* runs as a child of keventd. It runs with full root capabilities. keventd silently
* reaps the child when it exits.
* 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 zero on success, else a negative
* error code.
* Must be called from process context. Returns a negative error code
* if program was not execed successfully, or (exitcode << 8 + signal)
* of the application (0 if wait is not set).
*/
int call_usermodehelper(char *path, char **argv, char **envp)
int call_usermodehelper(char *path, char **argv, char **envp, int wait)
{
DECLARE_COMPLETION(done);
struct subprocess_info sub_info = {
......@@ -344,6 +226,7 @@ int call_usermodehelper(char *path, char **argv, char **envp)
.path = path,
.argv = argv,
.envp = envp,
.wait = wait,
.retval = 0,
};
DECLARE_WORK(work, __call_usermodehelper, &sub_info);
......@@ -381,7 +264,6 @@ void dev_probe_unlock(void)
up(&dev_probe_sem);
}
EXPORT_SYMBOL(exec_usermodehelper);
EXPORT_SYMBOL(call_usermodehelper);
#ifdef CONFIG_KMOD
......
......@@ -114,7 +114,7 @@ static int hci_run_hotplug(char *dev, char *action)
envp[3] = astr;
envp[4] = NULL;
return call_usermodehelper(argv[0], argv, envp);
return call_usermodehelper(argv[0], argv, envp, 0);
}
#else
#define hci_run_hotplug(A...)
......
......@@ -2942,6 +2942,6 @@ static int net_run_sbin_hotplug(struct net_device *dev, char *action)
envp [i++] = action_str;
envp [i] = 0;
return call_usermodehelper(argv [0], argv, envp);
return call_usermodehelper(argv [0], argv, envp, 0);
}
#endif
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