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coredump: make core dump functionality optional

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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>
This commit is contained in:
Alex Kelly 2012-10-04 17:15:23 -07:00 committed by Linus Torvalds
parent db9aeca97a
commit 046d662f48
6 changed files with 53 additions and 27 deletions
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8
fs/Kconfig.binfmt
View file

@ -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.

3
fs/Makefile
View file

@ -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

52
fs/binfmt_aout.c
View file

@ -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 @@ static int aout_core_dump(struct coredump_params *cprm)
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

4
include/linux/binfmts.h
View file

@ -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 *);

1
init/Kconfig
View file

@ -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

12
kernel/sysctl.c
View file

@ -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,