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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>
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Al Viro committed May 21, 2017
1 parent 7e95a22 commit ce72a16
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Showing 3 changed files with 59 additions and 48 deletions.
2 changes: 1 addition & 1 deletion include/linux/resource.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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);

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89 changes: 52 additions & 37 deletions kernel/exit.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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)
Expand Down Expand Up @@ -1316,8 +1319,9 @@ static int wait_task_stopped(struct wait_opts *wo,
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);

Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -1618,8 +1623,8 @@ static long do_wait(struct wait_opts *wo)
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;
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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

/*
Expand All @@ -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,
Expand All @@ -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))
Expand Down
16 changes: 6 additions & 10 deletions kernel/sys.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -1626,20 +1626,16 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
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
Expand All @@ -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
Expand Down

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