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Commit 63bb0045 authored by Tycho Andersen's avatar Tycho Andersen Committed by Kees Cook
Browse files

ptrace, seccomp: tweak get_metadata behavior slightly 



Previously if users passed a small size for the input structure size, they
would get get odd behavior. It doesn't make sense to pass a structure
smaller than at least filter_off size, so let's just give -EINVAL in this
case.

This changes userspace visible behavior, but was only introduced in commit
26500475 ("ptrace, seccomp: add support for retrieving seccomp
metadata") in 4.16-rc2, so should be safe to change if merged before then.

Reported-by: default avatarEugene Syromiatnikov <esyr@redhat.com>
Signed-off-by: default avatarTycho Andersen <tycho@tycho.ws>
CC: Kees Cook <keescook@chromium.org>
CC: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
parent 2a040f9f

kernel/seccomp.c

+4 −2
Original line number Diff line number Diff line
@@ -1076,14 +1076,16 @@ long seccomp_get_metadata(struct task_struct *task, 


	size = min_t(unsigned long, size, sizeof(kmd));



	if (copy_from_user(&kmd, data, size))

	if (size < sizeof(kmd.filter_off))

		return -EINVAL;



	if (copy_from_user(&kmd.filter_off, data, sizeof(kmd.filter_off)))

		return -EFAULT;



	filter = get_nth_filter(task, kmd.filter_off);

	if (IS_ERR(filter))

		return PTR_ERR(filter);



	memset(&kmd, 0, sizeof(kmd));

	if (filter->log)

		kmd.flags |= SECCOMP_FILTER_FLAG_LOG;