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Date: Wed, 6 May 2009 00:47:27 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Chris Wright <chrisw@...s-sol.org>,
Roland McGrath <roland@...hat.com>,
linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] ptrace: cleanup check/set of PT_PTRACED during attach
ptrace_attach() and ptrace_traceme() are the last functions which look as
if the untraced task can have task->ptrace != 0, this must not be possible.
Change the code to just check ->ptrace != 0 and s/|=/=/ to set PT_PTRACED.
Also, a couple of trivial whitespace cleanups in ptrace_attach().
And move ptrace_traceme() up near ptrace_attach() to keep them close to each
other.
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
kernel/ptrace.c | 102 ++++++++++++++++++++++++++++----------------------------
1 file changed, 51 insertions(+), 51 deletions(-)
--- PTRACE/kernel/ptrace.c~2_PTRACE 2009-05-05 23:17:53.000000000 +0200
+++ PTRACE/kernel/ptrace.c 2009-05-05 23:49:15.000000000 +0200
@@ -186,12 +186,12 @@ int ptrace_attach(struct task_struct *ta
goto out;
if (same_thread_group(task, current))
goto out;
-
- /* Protect exec's credential calculations against our interference;
+ /*
+ * Protect exec's credential calculations against our interference;
* SUID, SGID and LSM creds get determined differently under ptrace.
*/
retval = mutex_lock_interruptible(&task->cred_exec_mutex);
- if (retval < 0)
+ if (retval < 0)
goto out;
repeat:
/*
@@ -219,10 +219,10 @@ repeat:
retval = -EPERM;
if (unlikely(task->exit_state))
goto bad;
- if (task->ptrace & PT_PTRACED)
+ if (task->ptrace)
goto bad;
- task->ptrace |= PT_PTRACED;
+ task->ptrace = PT_PTRACED;
if (capable(CAP_SYS_PTRACE))
task->ptrace |= PT_PTRACE_CAP;
@@ -238,6 +238,52 @@ out:
return retval;
}
+/**
+ * ptrace_traceme -- helper for PTRACE_TRACEME
+ *
+ * Performs checks and sets PT_PTRACED.
+ * Should be used by all ptrace implementations for PTRACE_TRACEME.
+ */
+int ptrace_traceme(void)
+{
+ int ret = -EPERM;
+
+ /*
+ * Are we already being traced?
+ */
+repeat:
+ task_lock(current);
+ if (!current->ptrace) {
+ /*
+ * See ptrace_attach() comments about the locking here.
+ */
+ unsigned long flags;
+ if (!write_trylock_irqsave(&tasklist_lock, flags)) {
+ task_unlock(current);
+ do {
+ cpu_relax();
+ } while (!write_can_lock(&tasklist_lock));
+ goto repeat;
+ }
+
+ ret = security_ptrace_traceme(current->parent);
+
+ /*
+ * Check PF_EXITING to ensure ->real_parent has not passed
+ * exit_ptrace(). Otherwise we don't report the error but
+ * pretend ->real_parent untraces us right after return.
+ */
+ if (!ret && !(current->real_parent->flags & PF_EXITING)) {
+ current->ptrace = PT_PTRACED;
+ __ptrace_link(current, current->real_parent);
+ }
+
+ write_unlock_irqrestore(&tasklist_lock, flags);
+ }
+ task_unlock(current);
+ return ret;
+}
+
/*
* Called with irqs disabled, returns true if childs should reap themselves.
*/
@@ -575,52 +621,6 @@ int ptrace_request(struct task_struct *c
}
/**
- * ptrace_traceme -- helper for PTRACE_TRACEME
- *
- * Performs checks and sets PT_PTRACED.
- * Should be used by all ptrace implementations for PTRACE_TRACEME.
- */
-int ptrace_traceme(void)
-{
- int ret = -EPERM;
-
- /*
- * Are we already being traced?
- */
-repeat:
- task_lock(current);
- if (!(current->ptrace & PT_PTRACED)) {
- /*
- * See ptrace_attach() comments about the locking here.
- */
- unsigned long flags;
- if (!write_trylock_irqsave(&tasklist_lock, flags)) {
- task_unlock(current);
- do {
- cpu_relax();
- } while (!write_can_lock(&tasklist_lock));
- goto repeat;
- }
-
- ret = security_ptrace_traceme(current->parent);
-
- /*
- * Check PF_EXITING to ensure ->real_parent has not passed
- * exit_ptrace(). Otherwise we don't report the error but
- * pretend ->real_parent untraces us right after return.
- */
- if (!ret && !(current->real_parent->flags & PF_EXITING)) {
- current->ptrace |= PT_PTRACED;
- __ptrace_link(current, current->real_parent);
- }
-
- write_unlock_irqrestore(&tasklist_lock, flags);
- }
- task_unlock(current);
- return ret;
-}
-
-/**
* ptrace_get_task_struct -- grab a task struct reference for ptrace
* @pid: process id to grab a task_struct reference of
*
--
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