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coredump: add VM_NODUMP, MADV_NODUMP, MADV_CLEAR_NODUMP

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Since we no longer need the VM_ALWAYSDUMP flag, let's use the freed bit
for 'VM_NODUMP' flag.  The idea is is to add a new madvise() flag:
MADV_DONTDUMP, which can be set by applications to specifically request
memory regions which should not dump core.

The specific application I have in mind is qemu: we can add a flag there
that wouldn't dump all of guest memory when qemu dumps core.  This flag
might also be useful for security sensitive apps that want to absolutely
make sure that parts of memory are not dumped.  To clear the flag use:
MADV_DODUMP.

[akpm@linux-foundation.org: s/MADV_NODUMP/MADV_DONTDUMP/, s/MADV_CLEAR_NODUMP/MADV_DODUMP/, per Roland]
[akpm@linux-foundation.org: fix up the architectures which broke]
Signed-off-by: Jason Baron <jbaron@redhat.com>
Acked-by: Roland McGrath <roland@hack.frob.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jason Baron 2012-03-23 15:02:51 -07:00 committed by Linus Torvalds
parent 909af768e8
commit accb61fe7b
8 changed files with 32 additions and 0 deletions
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4
arch/alpha/include/asm/mman.h
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@ -56,6 +56,10 @@
#define MADV_HUGEPAGE 14 /* Worth backing with hugepages */
#define MADV_NOHUGEPAGE 15 /* Not worth backing with hugepages */
#define MADV_DONTDUMP 16 /* Explicity exclude from the core dump,
overrides the coredump filter bits */
#define MADV_DODUMP 17 /* Clear the MADV_NODUMP flag */
/* compatibility flags */
#define MAP_FILE 0

4
arch/mips/include/asm/mman.h
View File

@ -80,6 +80,10 @@
#define MADV_HUGEPAGE 14 /* Worth backing with hugepages */
#define MADV_NOHUGEPAGE 15 /* Not worth backing with hugepages */
#define MADV_DONTDUMP 16 /* Explicity exclude from the core dump,
overrides the coredump filter bits */
#define MADV_DODUMP 17 /* Clear the MADV_NODUMP flag */
/* compatibility flags */
#define MAP_FILE 0

4
arch/parisc/include/asm/mman.h
View File

@ -62,6 +62,10 @@
#define MADV_HUGEPAGE 67 /* Worth backing with hugepages */
#define MADV_NOHUGEPAGE 68 /* Not worth backing with hugepages */
#define MADV_DONTDUMP 69 /* Explicity exclude from the core dump,
overrides the coredump filter bits */
#define MADV_DODUMP 70 /* Clear the MADV_NODUMP flag */
/* compatibility flags */
#define MAP_FILE 0
#define MAP_VARIABLE 0

4
arch/xtensa/include/asm/mman.h
View File

@ -86,6 +86,10 @@
#define MADV_HUGEPAGE 14 /* Worth backing with hugepages */
#define MADV_NOHUGEPAGE 15 /* Not worth backing with hugepages */
#define MADV_DONTDUMP 16 /* Explicity exclude from the core dump,
overrides the coredump filter bits */
#define MADV_DODUMP 17 /* Clear the MADV_NODUMP flag */
/* compatibility flags */
#define MAP_FILE 0

3
fs/binfmt_elf.c
View File

@ -1127,6 +1127,9 @@ static unsigned long vma_dump_size(struct vm_area_struct *vma,
if (always_dump_vma(vma))
goto whole;
if (vma->vm_flags & VM_NODUMP)
return 0;
/* Hugetlb memory check */
if (vma->vm_flags & VM_HUGETLB) {
if ((vma->vm_flags & VM_SHARED) && FILTER(HUGETLB_SHARED))

4
include/asm-generic/mman-common.h
View File

@ -48,6 +48,10 @@
#define MADV_HUGEPAGE 14 /* Worth backing with hugepages */
#define MADV_NOHUGEPAGE 15 /* Not worth backing with hugepages */
#define MADV_DONTDUMP 16 /* Explicity exclude from the core dump,
overrides the coredump filter bits */
#define MADV_DODUMP 17 /* Clear the MADV_NODUMP flag */
/* compatibility flags */
#define MAP_FILE 0

1
include/linux/mm.h
View File

@ -111,6 +111,7 @@ extern unsigned int kobjsize(const void *objp);
#define VM_HUGEPAGE 0x01000000 /* MADV_HUGEPAGE marked this vma */
#endif
#define VM_INSERTPAGE 0x02000000 /* The vma has had "vm_insert_page()" done on it */
#define VM_NODUMP 0x04000000 /* Do not include in the core dump */
#define VM_CAN_NONLINEAR 0x08000000 /* Has ->fault & does nonlinear pages */
#define VM_MIXEDMAP 0x10000000 /* Can contain "struct page" and pure PFN pages */

8
mm/madvise.c
View File

@ -65,6 +65,12 @@ static long madvise_behavior(struct vm_area_struct * vma,
}
new_flags &= ~VM_DONTCOPY;
break;
case MADV_DONTDUMP:
new_flags |= VM_NODUMP;
break;
case MADV_DODUMP:
new_flags &= ~VM_NODUMP;
break;
case MADV_MERGEABLE:
case MADV_UNMERGEABLE:
error = ksm_madvise(vma, start, end, behavior, &new_flags);
@ -293,6 +299,8 @@ madvise_behavior_valid(int behavior)
case MADV_HUGEPAGE:
case MADV_NOHUGEPAGE:
#endif
case MADV_DONTDUMP:
case MADV_DODUMP:
return 1;
default: