coredump: add VM_NODUMP, MADV_NODUMP, MADV_CLEAR_NODUMP

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>

diff --git a/arch/alpha/include/asm/mman.h b/arch/alpha/include/asm/mman.h
index 72db984f8781391e1b1775f6c50a5699651e41db..cbeb3616a28edf22de663c7fc84c4fc11e13cf05 100644 (file)
--- a/arch/alpha/include/asm/mman.h
+++ b/arch/alpha/include/asm/mman.h
@@ -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
 

diff --git a/arch/mips/include/asm/mman.h b/arch/mips/include/asm/mman.h
index 785b4ea4ec3f5b3e39bbbc88dd7d3191e76abee2..46d3da0d4b92fb7af7c90c4912398b54e8907e69 100644 (file)
--- a/arch/mips/include/asm/mman.h
+++ b/arch/mips/include/asm/mman.h
@@ -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
 

diff --git a/arch/parisc/include/asm/mman.h b/arch/parisc/include/asm/mman.h
index f5b7bf5fba6837fb053a05f5394684b9421fe537..12219ebce8695d24bd651dad6a42cedee9e390ec 100644 (file)
--- a/arch/parisc/include/asm/mman.h
+++ b/arch/parisc/include/asm/mman.h
@@ -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

diff --git a/arch/xtensa/include/asm/mman.h b/arch/xtensa/include/asm/mman.h
index 30789010733d6dc045b352b63ea3363879c0503e..25bc6c1309c331a7c9328a7097018873832ac13d 100644 (file)
--- a/arch/xtensa/include/asm/mman.h
+++ b/arch/xtensa/include/asm/mman.h
@@ -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
 

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index b64be5b5ac218f03714f9c3813698975333a480a..504b6eee50a9ca47fc4aa3a4e9f691eb3095ad8c 100644 (file)
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -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))

diff --git a/include/asm-generic/mman-common.h b/include/asm-generic/mman-common.h
index 787abbb6d8676b942c4dd1b6b36f554ded8a4eb5..d030d2c2647ae513854d9795f2e84e1793811602 100644 (file)
--- a/include/asm-generic/mman-common.h
+++ b/include/asm-generic/mman-common.h
@@ -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
 

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 2de2ddba51d4c318738031f41254aeb4ac755af0..a6fabdfd34c56700205a16b31aa9982cbbad68af 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -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 */

diff --git a/mm/madvise.c b/mm/madvise.c
index f5ab745672b77fb2870d4c180b339b97dc0aec01..1ccbba5b667414e717db987b85da9e0f1691268f 100644 (file)
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -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: