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Commit ba2d0162 authored by Oleg Nesterov's avatar Oleg Nesterov
Browse files

exec: introduce struct user_arg_ptr 



No functional changes, preparation.

Introduce struct user_arg_ptr, change do_execve() paths to use it
instead of "char __user * const __user *argv".

This makes the argv/envp arguments opaque, we are ready to handle the
compat case which needs argv pointing to compat_uptr_t.

Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Reviewed-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Tested-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
parent 1d1dbf81

fs/exec.c

+30 −12
Original line number Original line Diff line number Diff line
@@ -398,12 +398,15 @@ err: 
	return err;

	return err;

}

}





static const char __user *

struct user_arg_ptr {

get_user_arg_ptr(const char __user * const __user *argv, int nr)

	const char __user *const __user *native;

};



static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)

{

{

	const char __user *ptr;

	const char __user *ptr;





	if (get_user(ptr, argv + nr))

	if (get_user(ptr, argv.native + nr))

		return ERR_PTR(-EFAULT);

		return ERR_PTR(-EFAULT);





	return ptr;

	return ptr;
@@ -412,11 +415,11 @@ get_user_arg_ptr(const char __user * const __user *argv, int nr) 
/*

/*

 * count() counts the number of strings in array ARGV.

 * count() counts the number of strings in array ARGV.

 */

 */

static int count(const char __user * const __user * argv, int max)

static int count(struct user_arg_ptr argv, int max)

{

{

	int i = 0;

	int i = 0;





	if (argv != NULL) {

	if (argv.native != NULL) {

		for (;;) {

		for (;;) {

			const char __user *p = get_user_arg_ptr(argv, i);

			const char __user *p = get_user_arg_ptr(argv, i);
@@ -442,7 +445,7 @@ static int count(const char __user * const __user * argv, int max) 
 * processes's memory to the new process's stack.  The call to get_user_pages()

 * processes's memory to the new process's stack.  The call to get_user_pages()

 * ensures the destination page is created and not swapped out.

 * ensures the destination page is created and not swapped out.

 */

 */

static int copy_strings(int argc, const char __user *const __user *argv,

static int copy_strings(int argc, struct user_arg_ptr argv,

			struct linux_binprm *bprm)

			struct linux_binprm *bprm)

{

{

	struct page *kmapped_page = NULL;

	struct page *kmapped_page = NULL;
@@ -533,14 +536,19 @@ out: 
/*

/*

 * Like copy_strings, but get argv and its values from kernel memory.

 * Like copy_strings, but get argv and its values from kernel memory.

 */

 */

int copy_strings_kernel(int argc, const char *const *argv,

int copy_strings_kernel(int argc, const char *const *__argv,

			struct linux_binprm *bprm)

			struct linux_binprm *bprm)

{

{

	int r;

	int r;

	mm_segment_t oldfs = get_fs();

	mm_segment_t oldfs = get_fs();

	struct user_arg_ptr argv = {

		.native = (const char __user *const  __user *)__argv,

	};



	set_fs(KERNEL_DS);

	set_fs(KERNEL_DS);

	r = copy_strings(argc, (const char __user *const  __user *)argv, bprm);

	r = copy_strings(argc, argv, bprm);

	set_fs(oldfs);

	set_fs(oldfs);



	return r;

	return r;

}

}

EXPORT_SYMBOL(copy_strings_kernel);

EXPORT_SYMBOL(copy_strings_kernel);
@@ -1393,9 +1401,9 @@ EXPORT_SYMBOL(search_binary_handler); 
/*

/*

 * sys_execve() executes a new program.

 * sys_execve() executes a new program.

 */

 */

int do_execve(const char * filename,

static int do_execve_common(const char *filename,

	const char __user *const __user *argv,

				struct user_arg_ptr argv,

	const char __user *const __user *envp,

				struct user_arg_ptr envp,

				struct pt_regs *regs)

				struct pt_regs *regs)

{

{

	struct linux_binprm *bprm;

	struct linux_binprm *bprm;
@@ -1503,6 +1511,16 @@ out_ret: 
	return retval;

	return retval;

}

}





int do_execve(const char *filename,

	const char __user *const __user *__argv,

	const char __user *const __user *__envp,

	struct pt_regs *regs)

{

	struct user_arg_ptr argv = { .native = __argv };

	struct user_arg_ptr envp = { .native = __envp };

	return do_execve_common(filename, argv, envp, regs);

}



void set_binfmt(struct linux_binfmt *new)

void set_binfmt(struct linux_binfmt *new)

{

{

	struct mm_struct *mm = current->mm;

	struct mm_struct *mm = current->mm;