[PATCH] use ptrace_get_task_struct in various places
The ptrace_get_task_struct() helper that I added as part of the ptrace
consolidation is useful in variety of places that currently opencode it.
Switch them to the common helpers.
Add a ptrace_traceme() helper that needs to be explicitly called, and simplify
the ptrace_get_task_struct() interface. We don't need the request argument
now, and we return the task_struct directly, using ERR_PTR() for error
returns. It's a bit more code in the callers, but we have two sane routines
that do one thing well now.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 656476e..cceaf09 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -408,54 +408,62 @@
return ret;
}
-#ifndef __ARCH_SYS_PTRACE
-static int ptrace_get_task_struct(long request, long pid,
- struct task_struct **childp)
+/**
+ * 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)
{
- struct task_struct *child;
int ret;
/*
- * Callers use child == NULL as an indication to exit early even
- * when the return value is 0, so make sure it is non-NULL here.
+ * Are we already being traced?
*/
- *childp = NULL;
+ if (current->ptrace & PT_PTRACED)
+ return -EPERM;
+ ret = security_ptrace(current->parent, current);
+ if (ret)
+ return -EPERM;
+ /*
+ * Set the ptrace bit in the process ptrace flags.
+ */
+ current->ptrace |= PT_PTRACED;
+ return 0;
+}
- if (request == PTRACE_TRACEME) {
- /*
- * Are we already being traced?
- */
- if (current->ptrace & PT_PTRACED)
- return -EPERM;
- ret = security_ptrace(current->parent, current);
- if (ret)
- return -EPERM;
- /*
- * Set the ptrace bit in the process ptrace flags.
- */
- current->ptrace |= PT_PTRACED;
- return 0;
- }
+/**
+ * ptrace_get_task_struct -- grab a task struct reference for ptrace
+ * @pid: process id to grab a task_struct reference of
+ *
+ * This function is a helper for ptrace implementations. It checks
+ * permissions and then grabs a task struct for use of the actual
+ * ptrace implementation.
+ *
+ * Returns the task_struct for @pid or an ERR_PTR() on failure.
+ */
+struct task_struct *ptrace_get_task_struct(pid_t pid)
+{
+ struct task_struct *child;
/*
- * You may not mess with init
+ * Tracing init is not allowed.
*/
if (pid == 1)
- return -EPERM;
+ return ERR_PTR(-EPERM);
- ret = -ESRCH;
read_lock(&tasklist_lock);
child = find_task_by_pid(pid);
if (child)
get_task_struct(child);
read_unlock(&tasklist_lock);
if (!child)
- return -ESRCH;
-
- *childp = child;
- return 0;
+ return ERR_PTR(-ESRCH);
+ return child;
}
+#ifndef __ARCH_SYS_PTRACE
asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
{
struct task_struct *child;
@@ -465,9 +473,16 @@
* This lock_kernel fixes a subtle race with suid exec
*/
lock_kernel();
- ret = ptrace_get_task_struct(request, pid, &child);
- if (!child)
+ if (request == PTRACE_TRACEME) {
+ ret = ptrace_traceme();
goto out;
+ }
+
+ child = ptrace_get_task_struct(pid);
+ if (IS_ERR(child)) {
+ ret = PTR_ERR(child);
+ goto out;
+ }
if (request == PTRACE_ATTACH) {
ret = ptrace_attach(child);