Commit f14c234b authored by Aleksa Sarai's avatar Aleksa Sarai Committed by Christian Brauner
Browse files

clone3: switch to copy_struct_from_user() 



Switch clone3() syscall from it's own copying struct clone_args from
userspace to the new dedicated copy_struct_from_user() helper.

The change is very straightforward, and helps unify the syscall
interface for struct-from-userspace syscalls. Additionally, explicitly
define CLONE_ARGS_SIZE_VER0 to match the other users of the
struct-extension pattern.

Signed-off-by: default avatarAleksa Sarai <cyphar@cyphar.com>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarChristian Brauner <christian.brauner@ubuntu.com>
[christian.brauner@ubuntu.com: improve commit message]
Link: https://lore.kernel.org/r/20191001011055.19283-3-cyphar@cyphar.com


Signed-off-by: default avatarChristian Brauner <christian.brauner@ubuntu.com>
parent f5a1a536

include/uapi/linux/sched.h

+2 −0
Original line number Diff line number Diff line
@@ -47,6 +47,8 @@ struct clone_args { 
	__aligned_u64 tls;

};



#define CLONE_ARGS_SIZE_VER0 64 /* sizeof first published struct */



/*

 * Scheduling policies

 */

kernel/fork.c

+7 −27
Original line number Diff line number Diff line
@@ -2525,39 +2525,19 @@ SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, 
#ifdef __ARCH_WANT_SYS_CLONE3

noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,

					      struct clone_args __user *uargs,

					      size_t size)

					      size_t usize)

{

	int err;

	struct clone_args args;



	if (unlikely(size > PAGE_SIZE))

	if (unlikely(usize > PAGE_SIZE))

		return -E2BIG;



	if (unlikely(size < sizeof(struct clone_args)))

	if (unlikely(usize < CLONE_ARGS_SIZE_VER0))

		return -EINVAL;



	if (unlikely(!access_ok(uargs, size)))

		return -EFAULT;



	if (size > sizeof(struct clone_args)) {

		unsigned char __user *addr;

		unsigned char __user *end;

		unsigned char val;



		addr = (void __user *)uargs + sizeof(struct clone_args);

		end = (void __user *)uargs + size;



		for (; addr < end; addr++) {

			if (get_user(val, addr))

				return -EFAULT;

			if (val)

				return -E2BIG;

		}



		size = sizeof(struct clone_args);

	}



	if (copy_from_user(&args, uargs, size))

		return -EFAULT;

	err = copy_struct_from_user(&args, sizeof(args), uargs, usize);

	if (err)

		return err;



	/*

	 * Verify that higher 32bits of exit_signal are unset and that

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