On Wed, Sep 23, 2020 at 04:18:26PM -0400, Gabriel Krisman Bertazi wrote:
Kees Cook keescook@chromium.org writes:
On Fri, Sep 04, 2020 at 04:31:39PM -0400, Gabriel Krisman Bertazi wrote:
Convert TIF_SECCOMP into a generic TI flag for any syscall interception work being done by the kernel. The actual type of work is exposed by a new flag field outside of thread_info. This ensures that the syscall_intercept field is only accessed if struct seccomp has to be accessed already, such that it doesn't incur in a much higher cost to the seccomp path.
In order to avoid modifying every architecture at once, this patch has a transition mechanism, such that architectures that define TIF_SECCOMP continue to work by ignoring the syscall_intercept flag, as long as they don't support other syscall interception mechanisms like the future syscall user dispatch. When migrating TIF_SECCOMP to TIF_SYSCALL_INTERCEPT, they should adopt the semantics of checking the syscall_intercept flag, like it is done in the common entry syscall code, or even better, migrate to the common syscall entry code.
Can we "eat" all the other flags like ptrace, audit, etc, too? Doing this only for seccomp seems strange.
Hi Kees, Thanks again for the review.
Yes, we can, and I'm happy to follow up with that as part of my TIF clean up work, but can we not block the current patchset to be merged waiting for that, as this already grew a lot from the original feature submission?
In that case, I'd say just add the new TIF flag. The consolidation can come later.