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tracehook: tracehook_expect_breakpoints

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This adds tracehook_expect_breakpoints() as a formal hook for the nommu
code to use for its, "Is text-poking likely?" check at mmap time.  This
names the actual semantics the code means to test, and documents it.

Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Reviewed-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Roland McGrath 2008-07-25 19:45:50 -07:00 committed by Linus Torvalds
parent 0d094efeb1
commit fa8e26ccd4
2 changed files with 17 additions and 2 deletions
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15
include/linux/tracehook.h
View file

@ -51,6 +51,21 @@
#include <linux/security.h>
struct linux_binprm;
/**
* tracehook_expect_breakpoints - guess if task memory might be touched
* @task: current task, making a new mapping
*
* Return nonzero if @task is expected to want breakpoint insertion in
* its memory at some point. A zero return is no guarantee it won't
* be done, but this is a hint that it's known to be likely.
*
* May be called with @task->mm->mmap_sem held for writing.
*/
static inline int tracehook_expect_breakpoints(struct task_struct *task)
{
return (task_ptrace(task) & PT_PTRACED) != 0;
}
/**
* tracehook_unsafe_exec - check for exec declared unsafe due to tracing
* @task: current task doing exec

4
mm/nommu.c
View file

@ -22,7 +22,7 @@
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/ptrace.h>
#include <linux/tracehook.h>
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include <linux/mount.h>
@ -745,7 +745,7 @@ static unsigned long determine_vm_flags(struct file *file,
* it's being traced - otherwise breakpoints set in it may interfere
* with another untraced process
*/
if ((flags & MAP_PRIVATE) && (current->ptrace & PT_PTRACED))
if ((flags & MAP_PRIVATE) && tracehook_expect_breakpoints(current))
vm_flags &= ~VM_MAYSHARE;
return vm_flags;