linux-kernel - [patch 2/2] ptrace: turn ptrace_access

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Date:	Thu, 7 May 2009 11:50:54 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Chris Wright <chrisw@...s-sol.org>
Cc:	Oleg Nesterov <oleg@...hat.com>,
	Roland McGrath <roland@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Al Viro <viro@...IV.linux.org.uk>
Subject: [patch 2/2] ptrace: turn ptrace_access_check() into a retval
	function

ptrace_access_check() returns a bool, while most of the ptrace 
access check machinery works with Linux retvals (where 0 indicates 
success, negative indicates an error).

So eliminate the bool and invert the usage at the call sites.

( Note: "< 0" checks are used instead of !0 checks, because that's
  the convention for retval checks and it results in similarly fast
  assembly code. )

[ Impact: cleanup ]

Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 fs/proc/array.c        |    2 +-
 fs/proc/base.c         |    8 ++++----
 fs/proc/task_mmu.c     |    2 +-
 include/linux/ptrace.h |    2 +-
 kernel/ptrace.c        |    6 ++++--
 5 files changed, 11 insertions(+), 9 deletions(-)

Index: linux/fs/proc/array.c
===================================================================
--- linux.orig/fs/proc/array.c
+++ linux/fs/proc/array.c
@@ -366,7 +366,7 @@ static int do_task_stat(struct seq_file 
 
 	state = *get_task_state(task);
 	vsize = eip = esp = 0;
-	permitted = ptrace_access_check(task, PTRACE_MODE_READ);
+	permitted = !ptrace_access_check(task, PTRACE_MODE_READ);
 	mm = get_task_mm(task);
 	if (mm) {
 		vsize = task_vsize(mm);
Index: linux/fs/proc/base.c
===================================================================
--- linux.orig/fs/proc/base.c
+++ linux/fs/proc/base.c
@@ -222,7 +222,7 @@ static int check_mem_permission(struct t
 		rcu_read_lock();
 		match = (tracehook_tracer_task(task) == current);
 		rcu_read_unlock();
-		if (match && ptrace_access_check(task, PTRACE_MODE_ATTACH))
+		if (match && !ptrace_access_check(task, PTRACE_MODE_ATTACH))
 			return 0;
 	}
 
@@ -322,7 +322,7 @@ static int proc_pid_wchan(struct task_st
 	wchan = get_wchan(task);
 
 	if (lookup_symbol_name(wchan, symname) < 0)
-		if (!ptrace_access_check(task, PTRACE_MODE_READ))
+		if (ptrace_access_check(task, PTRACE_MODE_READ) < 0)
 			return 0;
 		else
 			return sprintf(buffer, "%lu", wchan);
@@ -559,7 +559,7 @@ static int proc_fd_access_allowed(struct
 	 */
 	task = get_proc_task(inode);
 	if (task) {
-		allowed = ptrace_access_check(task, PTRACE_MODE_READ);
+		allowed = !ptrace_access_check(task, PTRACE_MODE_READ);
 		put_task_struct(task);
 	}
 	return allowed;
@@ -938,7 +938,7 @@ static ssize_t environ_read(struct file 
 	if (!task)
 		goto out_no_task;
 
-	if (!ptrace_access_check(task, PTRACE_MODE_READ))
+	if (ptrace_access_check(task, PTRACE_MODE_READ) < 0)
 		goto out;
 
 	ret = -ENOMEM;
Index: linux/fs/proc/task_mmu.c
===================================================================
--- linux.orig/fs/proc/task_mmu.c
+++ linux/fs/proc/task_mmu.c
@@ -656,7 +656,7 @@ static ssize_t pagemap_read(struct file 
 		goto out;
 
 	ret = -EACCES;
-	if (!ptrace_access_check(task, PTRACE_MODE_READ))
+	if (ptrace_access_check(task, PTRACE_MODE_READ) < 0)
 		goto out_task;
 
 	ret = -EINVAL;
Index: linux/include/linux/ptrace.h
===================================================================
--- linux.orig/include/linux/ptrace.h
+++ linux/include/linux/ptrace.h
@@ -101,7 +101,7 @@ extern void ptrace_fork(struct task_stru
 /* Returns 0 on success, -errno on denial. */
 extern int __ptrace_access_check(struct task_struct *task, unsigned int mode);
 /* Returns true on success, false on denial. */
-extern bool ptrace_access_check(struct task_struct *task, unsigned int mode);
+extern int ptrace_access_check(struct task_struct *task, unsigned int mode);
 
 static inline int ptrace_reparented(struct task_struct *child)
 {
Index: linux/kernel/ptrace.c
===================================================================
--- linux.orig/kernel/ptrace.c
+++ linux/kernel/ptrace.c
@@ -165,13 +165,15 @@ int __ptrace_access_check(struct task_st
 	return security_ptrace_access_check(task, mode);
 }
 
-bool ptrace_access_check(struct task_struct *task, unsigned int mode)
+int ptrace_access_check(struct task_struct *task, unsigned int mode)
 {
 	int err;
+
 	task_lock(task);
 	err = __ptrace_access_check(task, mode);
 	task_unlock(task);
-	return !err;
+
+	return err;
 }
 
 int ptrace_attach(struct task_struct *task)
--
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