coredump masking: add an interface for core dump filter

This patch adds an interface to set/reset flags which determines each memory
segment should be dumped or not when a core file is generated.

/proc/<pid>/coredump_filter file is provided to access the flags.  You can
change the flag status for a particular process by writing to or reading from
the file.

The flag status is inherited to the child process when it is created.

Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: David Howells <dhowells@redhat.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index ba39bdb2a7b8..469838998220 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -334,6 +334,8 @@ static struct mm_struct * mm_init(struct mm_struct * mm)
         atomic_set(&mm->mm_count, 1);
         init_rwsem(&mm->mmap_sem);
         INIT_LIST_HEAD(&mm->mmlist);
+        mm->flags = (current->mm) ? current->mm->flags
+                                  : MMF_DUMP_FILTER_DEFAULT;
         mm->core_waiters = 0;
         mm->nr_ptes = 0;
         set_mm_counter(mm, file_rss, 0);