Merge branch 'work.sys_wait' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull wait syscall updates from Al Viro:
 "Consolidating sys_wait* and compat counterparts.

  Gets rid of set_fs()/double-copy mess, simplifies the whole thing
  (lifting the copyouts to the syscalls means less headache in the part
  that does actual work - fewer failure exits, to start with), gets rid
  of the overhead of field-by-field __put_user()"

* 'work.sys_wait' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  osf_wait4: switch to kernel_wait4()
  waitid(): switch copyout of siginfo to unsafe_put_user()
  wait_task_zombie: consolidate info logics
  kill wait_noreap_copyout()
  lift getrusage() from wait_noreap_copyout()
  waitid(2): leave copyout of siginfo to syscall itself
  kernel_wait4()/kernel_waitid(): delay copying status to userland
  wait4(2)/waitid(2): separate copying rusage to userland
  move compat wait4 and waitid next to native variants

3 files changed, 170 insertions, 219 deletions

diff --git a/kernel/compat.c b/kernel/compat.c
index ebd8bdc3fd68..9ce1d4876e60 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -396,72 +396,6 @@ int put_compat_rusage(const struct rusage *r, struct compat_rusage __user *ru)
         return 0;
 }
 
-COMPAT_SYSCALL_DEFINE4(wait4,
-        compat_pid_t, pid,
-        compat_uint_t __user *, stat_addr,
-        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;
-        }
-}
-
-COMPAT_SYSCALL_DEFINE5(waitid,
-                int, which, compat_pid_t, pid,
-                struct compat_siginfo __user *, uinfo, int, options,
-                struct compat_rusage __user *, uru)
-{
-        siginfo_t info;
-        struct rusage ru;
-        long ret;
-        mm_segment_t old_fs = get_fs();
-
-        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);
-        set_fs(old_fs);
-
-        if ((ret < 0) || (info.si_signo == 0))
-                return ret;
-
-        if (uru) {
-                /* sys_waitid() overwrites everything in ru */
-                if (COMPAT_USE_64BIT_TIME)
-                        ret = copy_to_user(uru, &ru, sizeof(ru));
-                else
-                        ret = put_compat_rusage(&ru, uru);
-                if (ret)
-                        return -EFAULT;
-        }
-
-        BUG_ON(info.si_code & __SI_MASK);
-        info.si_code |= __SI_CHLD;
-        return copy_siginfo_to_user32(uinfo, &info);
-}
-
 static int compat_get_user_cpu_mask(compat_ulong_t __user *user_mask_ptr,
                                     unsigned len, struct cpumask *new_mask)
 {
diff --git a/kernel/exit.c b/kernel/exit.c
index c63226283aef..b0cc86a2d00b 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -62,6 +62,7 @@
 #include <linux/kcov.h>
 #include <linux/random.h>
 #include <linux/rcuwait.h>
+#include <linux/compat.h>
 
 #include <linux/uaccess.h>
 #include <asm/unistd.h>
@@ -982,14 +983,21 @@ SYSCALL_DEFINE1(exit_group, int, error_code)
         return 0;
 }
 
+struct waitid_info {
+        pid_t pid;
+        uid_t uid;
+        int status;
+        int cause;
+};
+
 struct wait_opts {
         enum pid_type           wo_type;
         int                     wo_flags;
         struct pid              *wo_pid;
 
-        struct siginfo __user   *wo_info;
-        int __user              *wo_stat;
-        struct rusage __user    *wo_rusage;
+        struct waitid_info      *wo_info;
+        int                     wo_stat;
+        struct rusage           *wo_rusage;
 
         wait_queue_entry_t              child_wait;
         int                     notask_error;
@@ -1036,34 +1044,6 @@ eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p)
         return 1;
 }
 
-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;
-
-        put_task_struct(p);
-        infop = wo->wo_info;
-        if (infop) {
-                if (!retval)
-                        retval = put_user(SIGCHLD, &infop->si_signo);
-                if (!retval)
-                        retval = put_user(0, &infop->si_errno);
-                if (!retval)
-                        retval = put_user((short)why, &infop->si_code);
-                if (!retval)
-                        retval = put_user(pid, &infop->si_pid);
-                if (!retval)
-                        retval = put_user(uid, &infop->si_uid);
-                if (!retval)
-                        retval = put_user(status, &infop->si_status);
-        }
-        if (!retval)
-                retval = pid;
-        return retval;
-}
-
 /*
  * Handle sys_wait4 work for one task in state EXIT_ZOMBIE.  We hold
  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
@@ -1072,30 +1052,23 @@ static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
  */
 static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
 {
-        int state, retval, status;
+        int state, status;
         pid_t pid = task_pid_vnr(p);
         uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p));
-        struct siginfo __user *infop;
+        struct waitid_info *infop;
 
         if (!likely(wo->wo_flags & WEXITED))
                 return 0;
 
         if (unlikely(wo->wo_flags & WNOWAIT)) {
-                int exit_code = p->exit_code;
-                int why;
-
+                status = p->exit_code;
                 get_task_struct(p);
                 read_unlock(&tasklist_lock);
                 sched_annotate_sleep();
-
-                if ((exit_code & 0x7f) == 0) {
-                        why = CLD_EXITED;
-                        status = exit_code >> 8;
-                } else {
-                        why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
-                        status = exit_code & 0x7f;
-                }
-                return wait_noreap_copyout(wo, p, pid, uid, why, status);
+                if (wo->wo_rusage)
+                        getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
+                put_task_struct(p);
+                goto out_info;
         }
         /*
          * Move the task's state to DEAD/TRACE, only one thread can do this.
@@ -1168,38 +1141,11 @@ 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);
         status = (p->signal->flags & SIGNAL_GROUP_EXIT)
                 ? p->signal->group_exit_code : p->exit_code;
-        if (!retval && wo->wo_stat)
-                retval = put_user(status, wo->wo_stat);
-
-        infop = wo->wo_info;
-        if (!retval && infop)
-                retval = put_user(SIGCHLD, &infop->si_signo);
-        if (!retval && infop)
-                retval = put_user(0, &infop->si_errno);
-        if (!retval && infop) {
-                int why;
-
-                if ((status & 0x7f) == 0) {
-                        why = CLD_EXITED;
-                        status >>= 8;
-                } else {
-                        why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
-                        status &= 0x7f;
-                }
-                retval = put_user((short)why, &infop->si_code);
-                if (!retval)
-                        retval = put_user(status, &infop->si_status);
-        }
-        if (!retval && infop)
-                retval = put_user(pid, &infop->si_pid);
-        if (!retval && infop)
-                retval = put_user(uid, &infop->si_uid);
-        if (!retval)
-                retval = pid;
+        wo->wo_stat = status;
 
         if (state == EXIT_TRACE) {
                 write_lock_irq(&tasklist_lock);
@@ -1216,7 +1162,21 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
         if (state == EXIT_DEAD)
                 release_task(p);
 
-        return retval;
+out_info:
+        infop = wo->wo_info;
+        if (infop) {
+                if ((status & 0x7f) == 0) {
+                        infop->cause = CLD_EXITED;
+                        infop->status = status >> 8;
+                } else {
+                        infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
+                        infop->status = status & 0x7f;
+                }
+                infop->pid = pid;
+                infop->uid = uid;
+        }
+
+        return pid;
 }
 
 static int *task_stopped_code(struct task_struct *p, bool ptrace)
@@ -1252,8 +1212,8 @@ static int *task_stopped_code(struct task_struct *p, bool ptrace)
 static int wait_task_stopped(struct wait_opts *wo,
                                 int ptrace, struct task_struct *p)
 {
-        struct siginfo __user *infop;
-        int retval, exit_code, *p_code, why;
+        struct waitid_info *infop;
+        int exit_code, *p_code, why;
         uid_t uid = 0; /* unneeded, required by compiler */
         pid_t pid;
 
@@ -1298,34 +1258,21 @@ unlock_sig:
         why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
         read_unlock(&tasklist_lock);
         sched_annotate_sleep();
+        if (wo->wo_rusage)
+                getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
+        put_task_struct(p);
 
-        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 (!retval && wo->wo_stat)
-                retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat);
+        if (likely(!(wo->wo_flags & WNOWAIT)))
+                wo->wo_stat = (exit_code << 8) | 0x7f;
 
         infop = wo->wo_info;
-        if (!retval && infop)
-                retval = put_user(SIGCHLD, &infop->si_signo);
-        if (!retval && infop)
-                retval = put_user(0, &infop->si_errno);
-        if (!retval && infop)
-                retval = put_user((short)why, &infop->si_code);
-        if (!retval && infop)
-                retval = put_user(exit_code, &infop->si_status);
-        if (!retval && infop)
-                retval = put_user(pid, &infop->si_pid);
-        if (!retval && infop)
-                retval = put_user(uid, &infop->si_uid);
-        if (!retval)
-                retval = pid;
-        put_task_struct(p);
-
-        BUG_ON(!retval);
-        return retval;
+        if (infop) {
+                infop->cause = why;
+                infop->status = exit_code;
+                infop->pid = pid;
+                infop->uid = uid;
+        }
+        return pid;
 }
 
 /*
@@ -1336,7 +1283,7 @@ unlock_sig:
  */
 static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
 {
-        int retval;
+        struct waitid_info *infop;
         pid_t pid;
         uid_t uid;
 
@@ -1361,22 +1308,20 @@ static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
         get_task_struct(p);
         read_unlock(&tasklist_lock);
         sched_annotate_sleep();
+        if (wo->wo_rusage)
+                getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
+        put_task_struct(p);
 
-        if (!wo->wo_info) {
-                retval = wo->wo_rusage
-                        ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
-                put_task_struct(p);
-                if (!retval && wo->wo_stat)
-                        retval = put_user(0xffff, wo->wo_stat);
-                if (!retval)
-                        retval = pid;
+        infop = wo->wo_info;
+        if (!infop) {
+                wo->wo_stat = 0xffff;
         } else {
-                retval = wait_noreap_copyout(wo, p, pid, uid,
-                                             CLD_CONTINUED, SIGCONT);
-                BUG_ON(retval == 0);
+                infop->cause = CLD_CONTINUED;
+                infop->pid = pid;
+                infop->uid = uid;
+                infop->status = SIGCONT;
         }
-
-        return retval;
+        return pid;
 }
 
 /*
@@ -1604,8 +1549,8 @@ 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 waitid_info *infop,
+                          int options, struct rusage *ru)
 {
         struct wait_opts wo;
         struct pid *pid = NULL;
@@ -1643,38 +1588,46 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
         wo.wo_pid       = pid;
         wo.wo_flags     = options;
         wo.wo_info      = infop;
-        wo.wo_stat      = NULL;
         wo.wo_rusage    = ru;
         ret = do_wait(&wo);
 
-        if (ret > 0) {
+        if (ret > 0)
                 ret = 0;
-        } else if (infop) {
-                /*
-                 * For a WNOHANG return, clear out all the fields
-                 * we would set so the user can easily tell the
-                 * difference.
-                 */
-                if (!ret)
-                        ret = put_user(0, &infop->si_signo);
-                if (!ret)
-                        ret = put_user(0, &infop->si_errno);
-                if (!ret)
-                        ret = put_user(0, &infop->si_code);
-                if (!ret)
-                        ret = put_user(0, &infop->si_pid);
-                if (!ret)
-                        ret = put_user(0, &infop->si_uid);
-                if (!ret)
-                        ret = put_user(0, &infop->si_status);
-        }
 
         put_pid(pid);
         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;
+        struct waitid_info info = {.status = 0};
+        long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL);
+
+        if (!err) {
+                if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
+                        return -EFAULT;
+        }
+        if (!infop)
+                return err;
+
+        user_access_begin();
+        unsafe_put_user(err ? 0 : SIGCHLD, &infop->si_signo, Efault);
+        unsafe_put_user(0, &infop->si_errno, Efault);
+        unsafe_put_user((short)info.cause, &infop->si_code, Efault);
+        unsafe_put_user(info.pid, &infop->si_pid, Efault);
+        unsafe_put_user(info.uid, &infop->si_uid, Efault);
+        unsafe_put_user(info.status, &infop->si_status, Efault);
+        user_access_end();
+        return err;
+Efault:
+        user_access_end();
+        return -EFAULT;
+}
+
+long kernel_wait4(pid_t upid, int __user *stat_addr, int options,
+                  struct rusage *ru)
 {
         struct wait_opts wo;
         struct pid *pid = NULL;
@@ -1702,14 +1655,29 @@ SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
         wo.wo_pid       = pid;
         wo.wo_flags     = options | WEXITED;
         wo.wo_info      = NULL;
-        wo.wo_stat      = stat_addr;
+        wo.wo_stat      = 0;
         wo.wo_rusage    = ru;
         ret = do_wait(&wo);
         put_pid(pid);
+        if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr))
+                ret = -EFAULT;
 
         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
 
 /*
@@ -1722,3 +1690,56 @@ SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
 }
 
 #endif
+
+#ifdef CONFIG_COMPAT
+COMPAT_SYSCALL_DEFINE4(wait4,
+        compat_pid_t, pid,
+        compat_uint_t __user *, stat_addr,
+        int, options,
+        struct compat_rusage __user *, ru)
+{
+        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,
+                int, which, compat_pid_t, pid,
+                struct compat_siginfo __user *, infop, int, options,
+                struct compat_rusage __user *, uru)
+{
+        struct rusage ru;
+        struct waitid_info info = {.status = 0};
+        long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL);
+
+        if (!err && uru) {
+                /* kernel_waitid() overwrites everything in ru */
+                if (COMPAT_USE_64BIT_TIME)
+                        err = copy_to_user(uru, &ru, sizeof(ru));
+                else
+                        err = put_compat_rusage(&ru, uru);
+                if (err)
+                        return -EFAULT;
+        }
+
+        if (!infop)
+                return err;
+
+        user_access_begin();
+        unsafe_put_user(err ? 0 : SIGCHLD, &infop->si_signo, Efault);
+        unsafe_put_user(0, &infop->si_errno, Efault);
+        unsafe_put_user((short)info.cause, &infop->si_code, Efault);
+        unsafe_put_user(info.pid, &infop->si_pid, Efault);
+        unsafe_put_user(info.uid, &infop->si_uid, Efault);
+        unsafe_put_user(info.status, &infop->si_status, Efault);
+        user_access_end();
+        return err;
+Efault:
+        user_access_end();
+        return -EFAULT;
+}
+#endif
diff --git a/kernel/sys.c b/kernel/sys.c
index 8a94b4eabcaa..dab1a0658a92 100644
--- 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