[PATCH 1/2] syscall,pid: Extract bodies of sys_get{pid,ppid}() into do_get{pid,ppid}()

Ben Hutchings
2010-09-26T15:09:41Z

Define do_get{pid,ppid}() for all architectures.

Change sys_get{pid,ppid}() to be wrappers for them, except on Alpha.
While we're at it, move them to the more obvious kernel/pid.c.

Change all callers accordingly.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
This is preparation for fixing sys_getxgid() on Alpha.

This applies on top of a previous quick-fix for TOMOYO
<http://article.gmane.org/gmane.linux.kernel.lsm/11708> which I hope to
see applied in 2.6.36.

Ben.

include/linux/pid.h | 4 ++++
kernel/auditsc.c | 4 ++--
kernel/pid.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
kernel/timer.c | 36 ------------------------------------
security/tomoyo/common.c | 6 +-----
5 files changed, 52 insertions(+), 43 deletions(-)

diff --git a/include/linux/pid.h b/include/linux/pid.h
index 49f1c2f..f79d402 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -188,4 +188,8 @@ pid_t pid_vnr(struct pid *pid);
} while_each_thread(tg___, task); \
task = tg___; \
} while_each_pid_task(pid, type, task)
+
+extern pid_t do_getpid(void);
+extern pid_t do_getppid(void);
+
#endif /* _LINUX_PID_H */
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 1b31c13..3c35ace 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -461,7 +461,7 @@ static int audit_filter_rules(struct task_struct *tsk,
case AUDIT_PPID:
if (ctx) {
if (!ctx->ppid)
- ctx->ppid = sys_getppid();
+ ctx->ppid = do_getppid();
result = audit_comparator(ctx->ppid, f->op, f->val);
}
break;
@@ -1320,7 +1320,7 @@ static void audit_log_exit(struct audit_context *context, struct task_struct *ts
/* tsk == current */
context->pid = tsk->pid;
if (!context->ppid)
- context->ppid = sys_getppid();
+ context->ppid = do_getppid();
cred = current_cred();
context->uid = cred->uid;
context->gid = cred->gid;
diff --git a/kernel/pid.c b/kernel/pid.c
index d55c6fb..89eb2c2 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -562,3 +562,48 @@ void __init pidmap_init(void)
init_pid_ns.pid_cachep = KMEM_CACHE(pid,
SLAB_HWCACHE_ALIGN | SLAB_PANIC);
}
+
+/**
+ * do_getpid - return the thread group id of the current process
+ *
+ * Note, despite the name, this returns the tgid not the pid. The tgid and
+ * the pid are identical unless CLONE_THREAD was specified on clone() in
+ * which case the tgid is the same in all threads of the same group.
+ *
+ * This is SMP safe as current->tgid does not change.
+ */
+pid_t do_getpid(void)
+{
+ return task_tgid_vnr(current);
+}
+
+/*
+ * Accessing ->real_parent is not SMP-safe, it could
+ * change from under us. However, we can use a stale
+ * value of ->real_parent under rcu_read_lock(), see
+ * release_task()->call_rcu(delayed_put_task_struct).
+ */
+pid_t do_getppid(void)
+{
+ pid_t pid;
+
+ rcu_read_lock();
+ pid = task_tgid_vnr(current->real_parent);
+ rcu_read_unlock();
+
+ return pid;
+}
+
+#ifndef __alpha__
+
+SYSCALL_DEFINE0(getpid)
+{
+ return do_getpid();
+}
+
+SYSCALL_DEFINE0(getppid)
+{
+ return do_getppid();
+}
+
+#endif
diff --git a/kernel/timer.c b/kernel/timer.c
index 97bf05b..6248883 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -1334,42 +1334,6 @@ SYSCALL_DEFINE1(alarm, unsigned int, seconds)

#ifndef __alpha__

-/*
- * The Alpha uses getxpid, getxuid, and getxgid instead. Maybe this
- * should be moved into arch/i386 instead?
- */
-
-/**
- * sys_getpid - return the thread group id of the current process
- *
- * Note, despite the name, this returns the tgid not the pid. The tgid and
- * the pid are identical unless CLONE_THREAD was specified on clone() in
- * which case the tgid is the same in all threads of the same group.
- *
- * This is SMP safe as current->tgid does not change.
- */
-SYSCALL_DEFINE0(getpid)
-{
- return task_tgid_vnr(current);
-}
-
-/*
- * Accessing ->real_parent is not SMP-safe, it could
- * change from under us. However, we can use a stale
- * value of ->real_parent under rcu_read_lock(), see
- * release_task()->call_rcu(delayed_put_task_struct).
- */
-SYSCALL_DEFINE0(getppid)
-{
- int pid;
-
- rcu_read_lock();
- pid = task_tgid_vnr(current->real_parent);
- rcu_read_unlock();
-
- return pid;
-}
-
SYSCALL_DEFINE0(getuid)
{
/* Only we change this so SMP safe */
diff --git a/security/tomoyo/common.c b/security/tomoyo/common.c
index c668b44..97192e1 100644
--- a/security/tomoyo/common.c
+++ b/security/tomoyo/common.c
@@ -1416,19 +1416,15 @@ static char *tomoyo_print_header(struct tomoyo_request_info *r)
const pid_t gpid = task_pid_nr(current);
static const int tomoyo_buffer_len = 4096;
char *buffer = kmalloc(tomoyo_buffer_len, GFP_NOFS);
- pid_t ppid;
if (!buffer)
return NULL;
do_gettimeofday(&tv);
- rcu_read_lock();
- ppid = task_tgid_vnr(current->real_parent);
- rcu_read_unlock();
snprintf(buffer, tomoyo_buffer_len - 1,
"#timestamp=%lu profile=%u mode=%s (global-pid=%u)"
" task={ pid=%u ppid=%u uid=%u gid=%u euid=%u"
" egid=%u suid=%u sgid=%u fsuid=%u fsgid=%u }",
tv.tv_sec, r->profile, tomoyo_mode[r->mode], gpid,
- task_tgid_vnr(current), ppid,
+ do_getpid(), do_getppid(),
current_uid(), current_gid(), current_euid(),
current_egid(), current_suid(), current_sgid(),
current_fsuid(), current_fsgid());
--
1.7.1