On Fri, Feb 24, 2012 at 7:21 PM, Will Drewry <wad@xxxxxxxxxxxx> wrote: > This change adds the SECCOMP_RET_ERRNO as a valid return value from a > seccomp filter. Additionally, it makes the first use of the lower > 16-bits for storing a filter-supplied errno. 16-bits is more than > enough for the errno-base.h calls. > > Returning errors instead of immediately terminating processes that > violate seccomp policy allow for broader use of this functionality > for kernel attack surface reduction. For example, a linux container > could maintain a whitelist of pre-existing system calls but drop > all new ones with errnos. This would keep a logically static attack > surface while providing errnos that may allow for graceful failure > without the downside of do_exit() on a bad call. > > v11: - check for NULL filter (keescook@xxxxxxxxxxxx) > v10: - change loaders to fn > v9: - n/a > v8: - update Kconfig to note new need for syscall_set_return_value. > - reordered such that TRAP behavior follows on later. > - made the for loop a little less indent-y > v7: - introduced > > Signed-off-by: Will Drewry <wad@xxxxxxxxxxxx> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> > + /* Ensure unexpected behavior doesn't result in failing open. */ > + if (unlikely(current->seccomp.filter == NULL)) > + ret = SECCOMP_RET_KILL; Any reason to not just immediately return in this case? -Kees -- Kees Cook ChromeOS Security -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
