wait4(2)/waitid(2): separate copying rusage to userland

New helpers: kernel_waitid() and kernel_wait4().  sys_waitid(),
sys_wait4() and their compat variants switched to those.  Copying
struct rusage to userland is left to syscall itself.  For
compat_sys_wait4() that eliminates the use of set_fs() completely.
For compat_sys_waitid() it's still needed (for siginfo handling);
that will change shortly.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/include/linux/resource.h b/include/linux/resource.h
index 5bc3116..277afda 100644 (file)
--- a/include/linux/resource.h
+++ b/include/linux/resource.h
@@ -6,7 +6,7 @@
 
 struct task_struct;
 
-int getrusage(struct task_struct *p, int who, struct rusage __user *ru);
+void getrusage(struct task_struct *p, int who, struct rusage *ru);
 int do_prlimit(struct task_struct *tsk, unsigned int resource,
                struct rlimit *new_rlim, struct rlimit *old_rlim);
 

diff --git a/kernel/exit.c b/kernel/exit.c
index f98782b..d44f129 100644 (file)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1003,7 +1003,7 @@ struct wait_opts {
 
        struct siginfo __user   *wo_info;
        int __user              *wo_stat;
-       struct rusage __user    *wo_rusage;
+       struct rusage           *wo_rusage;
 
        wait_queue_t            child_wait;
        int                     notask_error;
@@ -1054,8 +1054,10 @@ static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
                                pid_t pid, uid_t uid, int why, int status)
 {
        struct siginfo __user *infop;
-       int retval = wo->wo_rusage
-               ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
+       int retval = 0;
+
+       if (wo->wo_rusage)
+               getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
 
        put_task_struct(p);
        infop = wo->wo_info;
@@ -1182,8 +1184,9 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
                spin_unlock_irq(&current->sighand->siglock);
        }
 
-       retval = wo->wo_rusage
-               ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
+       if (wo->wo_rusage)
+               getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
+       retval = 0;
        status = (p->signal->flags & SIGNAL_GROUP_EXIT)
                ? p->signal->group_exit_code : p->exit_code;
        if (!retval && wo->wo_stat)
@@ -1316,8 +1319,9 @@ unlock_sig:
        if (unlikely(wo->wo_flags & WNOWAIT))
                return wait_noreap_copyout(wo, p, pid, uid, why, exit_code);
 
-       retval = wo->wo_rusage
-               ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
+       if (wo->wo_rusage)
+               getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
+       retval = 0;
        if (!retval && wo->wo_stat)
                retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat);
 
@@ -1377,8 +1381,9 @@ static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
        sched_annotate_sleep();
 
        if (!wo->wo_info) {
-               retval = wo->wo_rusage
-                       ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
+               if (wo->wo_rusage)
+                       getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
+               retval = 0;
                put_task_struct(p);
                if (!retval && wo->wo_stat)
                        retval = put_user(0xffff, wo->wo_stat);
@@ -1618,8 +1623,8 @@ end:
        return retval;
 }
 
-SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
-               infop, int, options, struct rusage __user *, ru)
+static long kernel_waitid(int which, pid_t upid, struct siginfo __user *infop,
+                         int options, struct rusage *ru)
 {
        struct wait_opts wo;
        struct pid *pid = NULL;
@@ -1687,8 +1692,21 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
        return ret;
 }
 
-SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
-               int, options, struct rusage __user *, ru)
+SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
+               infop, int, options, struct rusage __user *, ru)
+{
+       struct rusage r;
+       long err = kernel_waitid(which, upid, infop, options, ru ? &r : NULL);
+
+       if (!err) {
+               if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
+                       return -EFAULT;
+       }
+       return err;
+}
+
+static long kernel_wait4(pid_t upid, int __user *stat_addr,
+                       int options, struct rusage *ru)
 {
        struct wait_opts wo;
        struct pid *pid = NULL;
@@ -1724,6 +1742,19 @@ SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
        return ret;
 }
 
+SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
+               int, options, struct rusage __user *, ru)
+{
+       struct rusage r;
+       long err = kernel_wait4(upid, stat_addr, options, ru ? &r : NULL);
+
+       if (err > 0) {
+               if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
+                       return -EFAULT;
+       }
+       return err;
+}
+
 #ifdef __ARCH_WANT_SYS_WAITPID
 
 /*
@@ -1744,29 +1775,13 @@ COMPAT_SYSCALL_DEFINE4(wait4,
        int, options,
        struct compat_rusage __user *, ru)
 {
-       if (!ru) {
-               return sys_wait4(pid, stat_addr, options, NULL);
-       } else {
-               struct rusage r;
-               int ret;
-               unsigned int status;
-               mm_segment_t old_fs = get_fs();
-
-               set_fs (KERNEL_DS);
-               ret = sys_wait4(pid,
-                               (stat_addr ?
-                                (unsigned int __user *) &status : NULL),
-                               options, (struct rusage __user *) &r);
-               set_fs (old_fs);
-
-               if (ret > 0) {
-                       if (put_compat_rusage(&r, ru))
-                               return -EFAULT;
-                       if (stat_addr && put_user(status, stat_addr))
-                               return -EFAULT;
-               }
-               return ret;
+       struct rusage r;
+       long err = kernel_wait4(pid, stat_addr, options, ru ? &r : NULL);
+       if (err > 0) {
+               if (ru && put_compat_rusage(&r, ru))
+                       return -EFAULT;
        }
+       return err;
 }
 
 COMPAT_SYSCALL_DEFINE5(waitid,
@@ -1782,8 +1797,8 @@ COMPAT_SYSCALL_DEFINE5(waitid,
        memset(&info, 0, sizeof(info));
 
        set_fs(KERNEL_DS);
-       ret = sys_waitid(which, pid, (siginfo_t __user *)&info, options,
-                        uru ? (struct rusage __user *)&ru : NULL);
+       ret = kernel_waitid(which, pid, (siginfo_t __user *)&info, options,
+                        uru ? &ru : NULL);
        set_fs(old_fs);
 
        if ((ret < 0) || (info.si_signo == 0))

diff --git a/kernel/sys.c b/kernel/sys.c
index 8a94b4e..dab1a06 100644 (file)
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1552,7 +1552,7 @@ static void accumulate_thread_rusage(struct task_struct *t, struct rusage *r)
        r->ru_oublock += task_io_get_oublock(t);
 }
 
-static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
+void getrusage(struct task_struct *p, int who, struct rusage *r)
 {
        struct task_struct *t;
        unsigned long flags;
@@ -1626,20 +1626,16 @@ out:
        r->ru_maxrss = maxrss * (PAGE_SIZE / 1024); /* convert pages to KBs */
 }
 
-int getrusage(struct task_struct *p, int who, struct rusage __user *ru)
+SYSCALL_DEFINE2(getrusage, int, who, struct rusage __user *, ru)
 {
        struct rusage r;
 
-       k_getrusage(p, who, &r);
-       return copy_to_user(ru, &r, sizeof(r)) ? -EFAULT : 0;
-}
-
-SYSCALL_DEFINE2(getrusage, int, who, struct rusage __user *, ru)
-{
        if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN &&
            who != RUSAGE_THREAD)
                return -EINVAL;
-       return getrusage(current, who, ru);
+
+       getrusage(current, who, &r);
+       return copy_to_user(ru, &r, sizeof(r)) ? -EFAULT : 0;
 }
 
 #ifdef CONFIG_COMPAT
@@ -1651,7 +1647,7 @@ COMPAT_SYSCALL_DEFINE2(getrusage, int, who, struct compat_rusage __user *, ru)
            who != RUSAGE_THREAD)
                return -EINVAL;
 
-       k_getrusage(current, who, &r);
+       getrusage(current, who, &r);
        return put_compat_rusage(&r, ru);
 }
 #endif