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>

diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt
index 02257420274966b6f0085f20b148e1fe582bc865..0efd1524b9770844cf74899f067686073a1c730d 100644 (file)
--- a/fs/Kconfig.binfmt
+++ b/fs/Kconfig.binfmt
@@ -164,3 +164,11 @@ config BINFMT_MISC
          You may say M here for module support and later load the module when
          you have use for it; the module is called binfmt_misc. If you
          don't know what to answer at this point, say Y.
+
+config COREDUMP
+       bool "Enable core dump support" if EXPERT
+       default y
+       help
+         This option enables support for performing core dumps. You almost
+         certainly want to say Y here. Not necessary on systems that never
+         need debugging or only ever run flawless code.

diff --git a/fs/Makefile b/fs/Makefile
index 8938f8250320ecbde9ab3502141178ddd7492ad3..1d7af79288a04915ca0d1788bc84f32bd03793a0 100644 (file)
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -11,7 +11,7 @@ obj-y :=      open.o read_write.o file_table.o super.o \
                attr.o bad_inode.o file.o filesystems.o namespace.o \
                seq_file.o xattr.o libfs.o fs-writeback.o \
                pnode.o drop_caches.o splice.o sync.o utimes.o \
-               stack.o fs_struct.o statfs.o coredump.o
+               stack.o fs_struct.o statfs.o
 
 ifeq ($(CONFIG_BLOCK),y)
 obj-y +=       buffer.o bio.o block_dev.o direct-io.o mpage.o ioprio.o
@@ -48,6 +48,7 @@ obj-$(CONFIG_FS_MBCACHE)      += mbcache.o
 obj-$(CONFIG_FS_POSIX_ACL)     += posix_acl.o xattr_acl.o
 obj-$(CONFIG_NFS_COMMON)       += nfs_common/
 obj-$(CONFIG_GENERIC_ACL)      += generic_acl.o
+obj-$(CONFIG_COREDUMP)         += coredump.o
 
 obj-$(CONFIG_FHANDLE)          += fhandle.o
 

diff --git a/fs/binfmt_aout.c b/fs/binfmt_aout.c
index d146e181d10df8611050c16745195b9efca62c93..4b5b5117f00aff7a7ad707bc3c50ecce4e9c92ca 100644 (file)
--- 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

diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h
index 366422bc1633cecda39235276569f283faf0bf46..00e2e8908953d4eb314f4f91e720903ec309a45b 100644 (file)
--- a/include/linux/binfmts.h
+++ b/include/linux/binfmts.h
@@ -132,7 +132,11 @@ extern int copy_strings_kernel(int argc, const char *const *argv,
                               struct linux_binprm *bprm);
 extern int prepare_bprm_creds(struct linux_binprm *bprm);
 extern void install_exec_creds(struct linux_binprm *bprm);
+#ifdef CONFIG_COREDUMP
 extern void do_coredump(long signr, int exit_code, struct pt_regs *regs);
+#else
+static inline void do_coredump(long signr, int exit_code, struct pt_regs *regs) {}
+#endif
 extern void set_binfmt(struct linux_binfmt *new);
 extern void free_bprm(struct linux_binprm *);
 

diff --git a/init/Kconfig b/init/Kconfig
index e82f289290fa99fdd760e065f7169cb1575c8d03..ed6334dd5e718cb874e4b4d272b652fadb101a8d 100644 (file)
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1199,6 +1199,7 @@ config BUG
           Just say Y.
 
 config ELF_CORE
+       depends on COREDUMP
        default y
        bool "Enable ELF core dumps" if EXPERT
        help

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 84c76a34e41c7a01f3464506c5352cf00cf1f8ca..c2a2f8084bad0c95fbfc77ec08b2ee806d338097 100644 (file)
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -97,10 +97,12 @@
 extern int sysctl_overcommit_memory;
 extern int sysctl_overcommit_ratio;
 extern int max_threads;
-extern int core_uses_pid;
 extern int suid_dumpable;
+#ifdef CONFIG_COREDUMP
+extern int core_uses_pid;
 extern char core_pattern[];
 extern unsigned int core_pipe_limit;
+#endif
 extern int pid_max;
 extern int min_free_kbytes;
 extern int pid_max_min, pid_max_max;
@@ -177,8 +179,10 @@ static int proc_dointvec_minmax_sysadmin(struct ctl_table *table, int write,
 
 static int proc_dointvec_minmax_coredump(struct ctl_table *table, int write,
                void __user *buffer, size_t *lenp, loff_t *ppos);
+#ifdef CONFIG_COREDUMP
 static int proc_dostring_coredump(struct ctl_table *table, int write,
                void __user *buffer, size_t *lenp, loff_t *ppos);
+#endif
 
 #ifdef CONFIG_MAGIC_SYSRQ
 /* Note: sysrq code uses it's own private copy */
@@ -404,6 +408,7 @@ static struct ctl_table kern_table[] = {
                .mode           = 0644,
                .proc_handler   = proc_dointvec,
        },
+#ifdef CONFIG_COREDUMP
        {
                .procname       = "core_uses_pid",
                .data           = &core_uses_pid,
@@ -425,6 +430,7 @@ static struct ctl_table kern_table[] = {
                .mode           = 0644,
                .proc_handler   = proc_dointvec,
        },
+#endif
 #ifdef CONFIG_PROC_SYSCTL
        {
                .procname       = "tainted",
@@ -2036,12 +2042,14 @@ int proc_dointvec_minmax(struct ctl_table *table, int write,
 
 static void validate_coredump_safety(void)
 {
+#ifdef CONFIG_COREDUMP
        if (suid_dumpable == SUID_DUMPABLE_SAFE &&
            core_pattern[0] != '/' && core_pattern[0] != '|') {
                printk(KERN_WARNING "Unsafe core_pattern used with "\
                        "suid_dumpable=2. Pipe handler or fully qualified "\
                        "core dump path required.\n");
        }
+#endif
 }
 
 static int proc_dointvec_minmax_coredump(struct ctl_table *table, int write,
@@ -2053,6 +2061,7 @@ static int proc_dointvec_minmax_coredump(struct ctl_table *table, int write,
        return error;
 }
 
+#ifdef CONFIG_COREDUMP
 static int proc_dostring_coredump(struct ctl_table *table, int write,
                  void __user *buffer, size_t *lenp, loff_t *ppos)
 {
@@ -2061,6 +2070,7 @@ static int proc_dostring_coredump(struct ctl_table *table, int write,
                validate_coredump_safety();
        return error;
 }
+#endif
 
 static int __do_proc_doulongvec_minmax(void *data, struct ctl_table *table, int write,
                                     void __user *buffer,