On Fri, 25 Sep 2020 at 22:28, Kees Cook <keescook@xxxxxxxxxxxx> wrote: > > On Fri, Sep 25, 2020 at 08:33:59PM +0530, Pintu Agarwal wrote: > > This is regarding the KASLR feature support on ARM for the kernel > > version 4.9 and 4.14. > > > > Is KASLR supported on ARM-32 Linux 4.9 and above ? > > Sorry, this feature did not yet land in upstream: > https://github.com/KSPP/linux/issues/3 > > Here was the earlier effort: > https://lore.kernel.org/kernel-hardening/20170814125411.22604-1-ard.biesheuvel@xxxxxxxxxx/ > > > Is it dependent on CONFIG_RANDOMIZE_BASE or > > CONFIG_RANDOMIZE_BASE is what is used on other architectures to control > the feature. > > > /proc/sys/kernel/randomize_va_space ? > > Is there any relation between these two? > > No, the latter is about userspace addresses. > > > Is the changing kernel symbols (in every boot), only possible if KASLR > > is enabled, or there is another way it can happen? > > I think you meant kernel symbol addresses (not the symbols themselves). > But yes, I wouldn't expect the addresses to move if you didn't either > rebuild the kernel or had something else moving the kernel at boot (i.e. > the boot loader). > > > I have these queries because, > > In one of the arm-32 devices with Kernel 4.14, I observed that > > CONFIG_RANDOMIZE_BASE is not available. > > But /proc/sys/kernel/randomize_va_space is set to 2. > > However, I also observed that symbol addresses are changing in every boot. > > > > 1st boot cycle: > > [root ~]# cat /proc/kallsyms | grep "sys_open" > > a5b4de92 T sys_open > > [root@sa515m ~]# > > > > 2nd boot cycle: > > [root ~]# cat /proc/kallsyms | grep "sys_open" > > f546ed66 T sys_open > > > > So, I am wondering how this is possible without KASLR > > (CONFIG_RANDOMIZE_BASE) support in Kernel ? > Those addresses were obfuscated by kptr_restrict _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
