From 046d662f481830e652ac34cd112249adde16452a Mon Sep 17 00:00:00 2001 From: Alex Kelly Date: Thu, 4 Oct 2012 17:15:23 -0700 Subject: [PATCH] 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 Reviewed-by: Josh Triplett Acked-by: Serge Hallyn Acked-by: Kees Cook Cc: Randy Dunlap Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/Kconfig.binfmt | 8 +++++++ fs/Makefile | 3 ++- fs/binfmt_aout.c | 52 +++++++++++++++++++++-------------------- include/linux/binfmts.h | 4 ++++ init/Kconfig | 1 + kernel/sysctl.c | 12 +++++++++- 6 files changed, 53 insertions(+), 27 deletions(-) diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt index 022574202749..0efd1524b977 100644 --- 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 8938f8250320..1d7af79288a0 100644 --- 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 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 diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h index 366422bc1633..00e2e8908953 100644 --- 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 e82f289290fa..ed6334dd5e71 100644 --- 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 84c76a34e41c..c2a2f8084bad 100644 --- 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, -- 2.20.1