Hyperlink of the approach to bypass devmem_is_allowed checks is unavailable about sgx-step

[jovanbulck]

Thanks for reporting the broken link. The URL seems to have changed and is now available here. I'll update the README in a moment. However, you don't need to do anything, see note below.

NOTE: This link is only included to credit the approach and for interesting people to see what's going on beneath the hood. The devmem_is_allowed bypass approach is already implemented in /dev/sgxstep so it should work out of the box and not cause you any problems.

If you're interested, the code to handle this is this line:

https://github.com/jovanbulck/sgx-step/blob/master/kernel/sgxstep.c#L260

[xiaonan-INTC]

Thanks for the reply, jovanbulck. :).
But here is still an error as below, do you have solution for it?

/home/sgx-step/kernel/linux-sgx-driver/sgx_page_cache.c: In function ‘sgx_swap_pages’:
/home/sgx-step/kernel/linux-sgx-driver/sgx_page_cache.c:379:23: error: ‘struct mm_struct’ has no member named ‘mmap_sem’; did you mean ‘mmap_base’?
down_read(&encl->mm->mmap_sem);
^~~~~~~~
mmap_base
/home/sgx-step/kernel/linux-sgx-driver/sgx_page_cache.c:382:21: error: ‘struct mm_struct’ has no member named ‘mmap_sem’; did you mean ‘mmap_base’?
up_read(&encl->mm->mmap_sem);
^~~~~~~~
mmap_base
make[2]: *** [scripts/Makefile.build:271: /home/sgx-step/kernel/linux-sgx-driver/sgx_page_cache.o] Error 1
make[1]: *** [Makefile:1851: /home/sgx-step/kernel/linux-sgx-driver] Error 2
make[1]: Leaving directory '/usr/src/linux-headers-5.14.0-aex'
make: *** [Makefile:16: default] Error 2

BTW, didn't do following steps, are there any effects to this error?
$ sudo vim /etc/default/grub
//Add the following line: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nox2apic iomem=relaxed no_timer_check nosmep nosmap clearcpuid=514 isolcpus=1 nmi_watchdog=0"
$ sudo update-grub && reboot

[jovanbulck]

This seems to be an issue in the linux-sgx-driver. Currently, SGX-Step uses v2.11 that is not compatible with newer Linux kernels. This has been fixed in v2.14 and I pushed commits to SGX-Step to use the latest version v2.14 of the driver (plus also the latest linux-sgx SDK v2.16).

This should fix your issue hopefully. Let me know (by opening a new issue) if problems remain!