Messages in this thread | | | From | Paul Moore <> | Date | Fri, 14 May 2021 16:33:43 -0400 | Subject | Re: [PATCH v2 3/3] audit: Use syscall_get_return_value to get syscall return code in audit_syscall_exit |
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On Wed, May 12, 2021 at 4:43 AM He Zhe <zhe.he@windriver.com> wrote: > On 5/11/21 10:51 PM, Paul Moore wrote: > > On Mon, May 10, 2021 at 11:19 PM He Zhe <zhe.he@windriver.com> wrote: > >> On 5/11/21 6:38 AM, Paul Moore wrote: > >>> On Fri, Apr 23, 2021 at 6:36 AM He Zhe <zhe.he@windriver.com> wrote: > >>>> regs_return_value for some architectures like arm64 simply retrieve > >>>> register value from pt_regs without sign extension in 32-bit compatible > >>>> case and cause audit to have false syscall return code. For example, > >>>> 32-bit -13 would be treated as 4294967283 below. > >>>> > >>>> type=SYSCALL msg=audit(1611110715.887:582): arch=40000028 syscall=322 > >>>> success=yes exit=4294967283 > >>>> > >>>> We just added proper sign extension in syscall_get_return_value which > >>>> should be used instead. > >>>> > >>>> Signed-off-by: He Zhe <zhe.he@windriver.com> > >>>> --- > >>>> v1 to v2: No change > >>>> > >>>> include/linux/audit.h | 2 +- > >>>> 1 file changed, 1 insertion(+), 1 deletion(-) > >>> Perhaps I missed it but did you address the compile error that was > >>> found by the kernel test robot? > >> I sent a patch adding syscall_get_return_value for alpha to fix this bot warning. > >> https://lore.kernel.org/lkml/20210426091629.45020-1-zhe.he@windriver.com/ > >> which can be found in this mail thread. > > At the very least you should respin the patchset with the alpha fix > > included in the patchset; it's a bit messy otherwise. > > > >>>> diff --git a/include/linux/audit.h b/include/linux/audit.h > >>>> index 82b7c1116a85..135adbe22c19 100644 > >>>> --- a/include/linux/audit.h > >>>> +++ b/include/linux/audit.h > >>>> @@ -334,7 +334,7 @@ static inline void audit_syscall_exit(void *pt_regs) > >>>> { > >>>> if (unlikely(audit_context())) { > >>>> int success = is_syscall_success(pt_regs); > >>> Since we are shifting to use syscall_get_return_value() below, would > >>> it also make sense to shift to using syscall_get_error() here instead > >>> of is_syscall_success()? > >> In [PATCH v2 1/3], is_syscall_success calls syscall_get_return_value to take > >> care of the sign extension issue. Keeping using is_syscall_success is to not > >> potentially changing other architectures' behavior. > > That was only for aarch64, right? What about all the other > > architectures? The comment block for syscall_get_return_value() > > advises that syscall_get_error() should be used and that appears to be > > what is done in the ptrace code. > > Yes, it was only for aarch64. No similar issue hasn't observed for other > architectures on my side, so I was trying to minimize the impact. > > The "comment block" you mentioned is the following line, right? > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/asm-generic/syscall.h#n77 > [PATCH v2 2/3] was used to cover this concern. But as we can see in > Mark Rutland's last reply, there'are more things to be considered and we are > still trying to find a proper solution.
It sounds like you are going to be submitting another patchset at some point in the future - that's good - when you do please use syscall_get_error() in conjunction with syscall_get_return_value() or explain why doing so is wrong. The explanation should be in a code comment, not just an email and/or commit description.
-- paul moore www.paul-moore.com
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