coredump: make core dump functionality optional

Adds an expert Kconfig option, CONFIG_COREDUMP, which allows disabling of
core dump.  This saves approximately 2.6k in the compiled kernel, and
complements CONFIG_ELF_CORE, which now depends on it.

CONFIG_COREDUMP also disables coredump-related sysctls, except for
suid_dumpable and related functions, which are necessary for ptrace.

[akpm@linux-foundation.org: fix binfmt_aout.c build]
Signed-off-by: Alex Kelly <alex.page.kelly@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 27 insertions, 25 deletions

diff --git a/fs/binfmt_aout.c b/fs/binfmt_aout.c
index d146e181d10d..4b5b5117f00a 100644
--- a/fs/binfmt_aout.c
+++ b/fs/binfmt_aout.c
@@ -32,31 +32,8 @@
 
 static int load_aout_binary(struct linux_binprm *, struct pt_regs * regs);
 static int load_aout_library(struct file*);
-static int aout_core_dump(struct coredump_params *cprm);
-
-static struct linux_binfmt aout_format = {
-        .module         = THIS_MODULE,
-        .load_binary    = load_aout_binary,
-        .load_shlib     = load_aout_library,
-        .core_dump      = aout_core_dump,
-        .min_coredump   = PAGE_SIZE
-};
-
-#define BAD_ADDR(x)     ((unsigned long)(x) >= TASK_SIZE)
-
-static int set_brk(unsigned long start, unsigned long end)
-{
-        start = PAGE_ALIGN(start);
-        end = PAGE_ALIGN(end);
-        if (end > start) {
-                unsigned long addr;
-                addr = vm_brk(start, end - start);
-                if (BAD_ADDR(addr))
-                        return addr;
-        }
-        return 0;
-}
 
+#ifdef CONFIG_COREDUMP
 /*
  * Routine writes a core dump image in the current directory.
  * Currently only a stub-function.
@@ -66,7 +43,6 @@ static int set_brk(unsigned long start, unsigned long end)
  * field, which also makes sure the core-dumps won't be recursive if the
  * dumping of the process results in another error..
  */
-
 static int aout_core_dump(struct coredump_params *cprm)
 {
         struct file *file = cprm->file;
@@ -135,6 +111,32 @@ end_coredump:
         set_fs(fs);
         return has_dumped;
 }
+#else
+#define aout_core_dump NULL
+#endif
+
+static struct linux_binfmt aout_format = {
+        .module         = THIS_MODULE,
+        .load_binary    = load_aout_binary,
+        .load_shlib     = load_aout_library,
+        .core_dump      = aout_core_dump,
+        .min_coredump   = PAGE_SIZE
+};
+
+#define BAD_ADDR(x)     ((unsigned long)(x) >= TASK_SIZE)
+
+static int set_brk(unsigned long start, unsigned long end)
+{
+        start = PAGE_ALIGN(start);
+        end = PAGE_ALIGN(end);
+        if (end > start) {
+                unsigned long addr;
+                addr = vm_brk(start, end - start);
+                if (BAD_ADDR(addr))
+                        return addr;
+        }
+        return 0;
+}
 
 /*
  * create_aout_tables() parses the env- and arg-strings in new user