RFE: add RISC-V 64-bit support

[andreas-schwab]

No description provided.

[coveralls]

Coverage decreased (-0.05%) to 89.763% when pulling ddbc2aa on andreas-schwab:master into ed3b35c on seccomp:master.

[pcmoore]

@drakenclimber I'm thinking this is worth adding to the v2.5 milestone, assuming everything is working and look okay. Thoughts?

[drakenclimber]

@drakenclimber I'm thinking this is worth adding to the v2.5 milestone, assuming everything is working and look okay. Thoughts?

Yes, I agree. This would be a really good addition for v2.5

[carlosedp]

Hi folks, any news on this? Is it scheduled to be included on next version?
Thanks!

[drakenclimber]

Hi folks, any news on this? Is it scheduled to be included on next version?
Thanks!

I'm still planning on trying to get it into v2.5. (Not sure yet on v2.5's release date yet, but pressure is growing to get it out.)

I'll try to review this code this week. Thanks!

[drakenclimber]

The changes look reasonable to me. I had a few nitpick comments that would be good to address but nothing major.

I also ran the changes through arch-syscall-validate and the RISC-V stuff all passed.

Acked-by: Tom Hromatka <tom.hromatka@oracle.com>

[pcmoore]

In keeping with the other tokens in seccomp.h, I would have expected AUDIT_ARCH_RISCV64 to be defined before it was used. However, if that is the only nit in this review we can move that while merging.

[pcmoore]

Merged into master via 5432e15, thanks everyone!

@andreas-schwab please re-test with master just to make sure everything is still working (neither @drakenclimber or myself have RISC-V machines), and please make an attempt to test the libseccomp releases to make sure we don't break anything in the future :)

[carlosedp]

Amazing, thanks everyone!
Cc. @davidlt

[pcmoore]

@carlosedp if you've got a RISC-V system handy, we would appreciate some extra testing help :)

[andreas-schwab]

https://build.opensuse.org/package/live_build_log/home:Andreas_Schwab:Factory/libseccomp/r/riscv64

[carlosedp]

Hey @pcmoore, I've built and tested libseccomp on my RISC-V board. All good:

...
Regression Test Summary
 tests run: 5229
 tests skipped: 114
 tests passed: 5229
 tests failed: 0
 tests errored: 0

[pcmoore]

@andreas-schwab I see a single failure in your test run:

[ 5388s] Test 52-basic-load%%001-00001 result:   FAILURE 52-basic-load rc=22

... is this maybe due to the build/CI tool either not allowing seccomp policies to be loaded, or simply running a kernel that doesn't support seccomp-bpf?

[andreas-schwab]

What is needed to support seccomp-bpf? The same error happens on armv7l, and that runs natively. There are no restrictions on what a kernel can do in OBS.

[pcmoore]

At the very least the kernel needs to be build with support for CONFIG_SECCOMP_FILTER, which is dependent upon HAVE_ARCH_SECCOMP_FILTER that is defined in the arch/ABI specific kernel code.

Are you building your own kernels @andreas-schwab or are you using distro-kernels?

[andreas-schwab]

This is a normal distro build, as you can see from the logfile, and CONFIG_SECCOMP_FILTER is enabled in all kernels.

[pcmoore]

This is a normal distro build, as you can see from the logfile, and CONFIG_SECCOMP_FILTER is enabled in all kernels.

Hmm, any chance you can help us debug why the load test was failing?

[pcmoore]

I'm going to reopen this issue until we can resolve this last problem.

Since @carlosedp got a clean run on a RISC-V board I'm guessing there is just some problem with the OBS build and not a larger problem with libseccomp on RISC-V.

[andreas-schwab]

The riscv64 failure is due to qemu-linux-user rejecting to emulate seccomp.

[andreas-schwab]

For the armv7l failure I see this:

prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) = 0
seccomp(SECCOMP_SET_MODE_STRICT, 1, NULL) = -1 EINVAL (Invalid argument)
seccomp(SECCOMP_SET_MODE_FILTER, 0, {len=4, filter=0x50e400}) = -1 EINVAL (Invalid argument)

[pcmoore]

Looks like I can't reopen this issue, bummer.

[pcmoore]

The riscv64 failure is due to qemu-linux-user rejecting to emulate seccomp.

Okay, I think we can ignore that failure then, thank you.

For the armv7l failure I see this:

prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) = 0
seccomp(SECCOMP_SET_MODE_STRICT, 1, NULL) = -1 EINVAL (Invalid argument)
seccomp(SECCOMP_SET_MODE_FILTER, 0, {len=4, filter=0x50e400}) = -1 EINVAL (Invalid argument)

The fist call prctl(PR_SET_NO_NEW_PRIVS, ...) sets NO_NEW_PRIVS, which is expected (anc configurable via a filter attribute. Regardless, it succeeds so there is nothing to worry about there.

The seccomp(SECCOMP_SET_MODE_STRICT, 1, NULL) is also expected as it is a quick test to see if the system supports the seccomp syscall, see the sys_chk_seccomp_syscall() function for more information. In this case it appears to return EINVAL which indicates that the system does support the seccomp() syscall; this is good and expected.

However, the final syscall, seccomp(SECCOMP_SET_MODE_FILTER, 0, {len=4, filter=0x50e400}) is a bit confusing as it returns EINVAL indicating an error. The len=4 tells us that the BPF filter contains four instructions, which I would expect (load ABI token, compare ABI token and jump to good/bad ABI, return ALLOW, return KILL). Are you 100% that this kernel is build with CONFIG_SECCOMP_FILTER?

[andreas-schwab]

No, it doesn't, because it has OABI_COMPAT enabled.

[pcmoore]

Ah, ha! Mystery solved :)