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Message-Id: <20170515223716.2085-2-viro@ZenIV.linux.org.uk>
Date: Mon, 15 May 2017 23:37:10 +0100
From: Al Viro <viro@...IV.linux.org.uk>
To: linux-kernel@...r.kernel.org
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
Ingo Molnar <mingo@...nel.org>,
Oleg Nesterov <oleg@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Christoph Hellwig <hch@....de>
Subject: [PATCH 2/8] wait4(2)/waitid(2): separate copying rusage to userland
From: Al Viro <viro@...iv.linux.org.uk>
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@...iv.linux.org.uk>
---
include/linux/resource.h | 2 +-
kernel/exit.c | 89 ++++++++++++++++++++++++++++--------------------
kernel/sys.c | 16 ++++-----
3 files changed, 59 insertions(+), 48 deletions(-)
diff --git a/include/linux/resource.h b/include/linux/resource.h
index 5bc3116e649c..277afdad6589 100644
--- 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 197878103b25..b3c141a4432f 100644
--- 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(¤t->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 @@ 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);
@@ -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 @@ 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;
@@ -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 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 @@ 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
@@ -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
--
2.11.0
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