On Mon, Jun 28, 2021 at 9:25 AM Thomas Weißschuh <linux@xxxxxxxxxxxxxx> wrote: > > Hi everyone, > > there does not seem to be a way to access the AUDIT_ARCH_ constant that matches > the currently visible syscall numbers (__NR_...) from the kernel uapi headers. Looking at Linus' current tree I see the AUDIT_ARCH_* defines in include/uapi/linux/audit.h; looking on my system right now I see the defines in /usr/include/linux/audit.h. What kernel repository and distribution are you using? > Questions: > > Is it really necessary to validate the arch value when syscall numbers are > already target-specific? > (If not, should this be added to the docs?) Checking the arch/ABI value is important so that you can ensure that you are using the syscall number in the proper context. For example, look at the access(2) syscall: it is undefined on some ABIs and can take either a value of 20, 21, or 33 depending on the arch/ABI. Unfortunately this is rather common. Checking the arch/ABI value is also handy if you want to quickly disallow certain ABIs on a system that supports multiple ABI, e.g. disabling 32-bit x86 on a 64-bit x86_64 system. > Would it make sense to expose the audit arch matching the syscall numbers in > the uapi headers? Yes, which is why the existing headers do so ;) If you don't see the header files I mentioned above, it may be worth checking your kernel source repository and your distribution's installed kernel header files. -- paul moore www.paul-moore.com
