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

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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>
This commit is contained in:
Al Viro 2017-05-14 20:25:02 -04:00
parent 7e95a22590
commit ce72a16fa7
3 changed files with 59 additions and 48 deletions
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2
include/linux/resource.h
View File

@ -6,7 +6,7 @@
struct task_struct; 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, int do_prlimit(struct task_struct *tsk, unsigned int resource,
struct rlimit *new_rlim, struct rlimit *old_rlim); struct rlimit *new_rlim, struct rlimit *old_rlim);

89
kernel/exit.c
View File

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

16
kernel/sys.c
View File

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