Re: [PATCH v2 3/3] audit: Use syscall_get_return_value to get syscall return code in audit_syscall_exit

On 5/11/21 10:51 PM, Paul Moore wrote: > On Mon, May 10, 2021 at 11:19 PM He Zhe <zhe.he(a)windriver.com&gt; wrote: >> On 5/11/21 6:38 AM, Paul Moore wrote: >>> On Fri, Apr 23, 2021 at 6:36 AM He Zhe <zhe.he(a)windriver.com&gt; 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(a)windriver.com&gt; >>>> --- >>>> 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/i... [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.