Le mercredi 29 mai 2019 à 17:22 +0200, Christian Brauner a écrit :
> This adds the clone3 system call.
>
>
> diff --git a/kernel/fork.c b/kernel/fork.c
> index b4cba953040a..6bc3e3d17150 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -2472,7 +2475,96 @@ SYSCALL_DEFINE5(clone, unsigned long, clone_flags,
> unsigned long, newsp,
> unsigned long, tls)
> #endif
> {
> - return _do_fork(clone_flags, newsp, 0, parent_tidptr, child_tidptr,
> tls);
> + struct kernel_clone_args args = {
> + .flags = clone_flags,
> + .stack = newsp,
> + .pidfd = parent_tidptr,
> + .parent_tidptr = parent_tidptr,
> + .tls = tls,
> + .child_tidptr = child_tidptr,
> + };
> +
> + /* clone(CLONE_PIDFD) uses parent_tidptr to return a pidfd */
> + if ((clone_flags & CLONE_PIDFD) && (clone_flags & CLONE_PARENT_SETTID))
> + return -EINVAL;
> +
> + return _do_fork(&args);
> +}
> +
> +static bool clone3_flags_valid(u64 flags)
> +{
> + if (flags & CLONE_DETACHED)
> + return false;
> +
> + if (flags & ~CLONE_MAX)
> + return false;
> +
> + return true;
> +}
> +
> +static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
> + struct clone_args __user *uargs,
> + size_t size)
> +{
> + struct clone_args args;
> +
> + if (unlikely(size > PAGE_SIZE))
> + return -E2BIG;
> +
> + if (unlikely(size < sizeof(struct clone_args)))
> + 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;
Should be -EINVAL: having something after the structure should be
handled just like an invalid flags, while still allowing future
userspace program to probe for support for newer feature.
> + }
> +
> + size = sizeof(struct clone_args);
> + }
> +
> + if (copy_from_user(&args, uargs, size))
> + return -EFAULT;
> +
> + if (!clone3_flags_valid(args.flags))
> + return -EINVAL;
> +
> + memset(kargs, 0, sizeof(*kargs));
> +
> + kargs->flags = args.flags;
> + kargs->child_tidptr = u64_to_user_ptr(args.child_tidptr);
> + kargs->parent_tidptr = u64_to_user_ptr(args.parent_tidptr);
> + kargs->pidfd = u64_to_user_ptr(args.pidfd);
> + kargs->stack = args.stack;
> + kargs->stack_size = args.stack_size;
> + kargs->tls = args.tls;
> +
> + return 0;
> +}
> +
> +SYSCALL_DEFINE2(clone3, struct clone_args __user *, uargs, size_t, size)
> +{
> + int err;
> +
> + struct kernel_clone_args kargs;
> +
> + err = copy_clone_args_from_user(&kargs, uargs, size);
> + if (err)
> + return err;
> +
> + return _do_fork(&kargs);
> }
> #endif
>
Regards.
--
Yann Droneaud
OPTEYA
