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, 14 insertions, 0 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 8dbd08366400..94f624aef017 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -349,8 +349,22 @@ extern void set_dumpable(struct mm_struct *mm, int value);
 extern int get_dumpable(struct mm_struct *mm);
 
 /* mm flags */
+/* dumpable bits */
 #define MMF_DUMPABLE      0  /* core dump is permitted */
 #define MMF_DUMP_SECURELY 1  /* core file is readable only by root */
+#define MMF_DUMPABLE_BITS 2
+
+/* coredump filter bits */
+#define MMF_DUMP_ANON_PRIVATE   2
+#define MMF_DUMP_ANON_SHARED    3
+#define MMF_DUMP_MAPPED_PRIVATE 4
+#define MMF_DUMP_MAPPED_SHARED  5
+#define MMF_DUMP_FILTER_SHIFT   MMF_DUMPABLE_BITS
+#define MMF_DUMP_FILTER_BITS    4
+#define MMF_DUMP_FILTER_MASK \
+        (((1 << MMF_DUMP_FILTER_BITS) - 1) << MMF_DUMP_FILTER_SHIFT)
+#define MMF_DUMP_FILTER_DEFAULT \
+        ((1 << MMF_DUMP_ANON_PRIVATE) | (1 << MMF_DUMP_ANON_SHARED))
 
 struct mm_struct {
         struct vm_area_struct * mmap;           /* list of VMAs */