[PATCH] eal/linux: enhance ASLR verification

[Stephen Hemminger]

On Wed, 12 Mar 2025 11:13:27 +0800
Yang Ming <ming.1.yang at nokia-sbell.com> wrote:

> On 2025/3/11 05:43, Stephen Hemminger wrote:
> > Caution: This is an external email. Please be very careful when clicking links or opening attachments. See http://nok.it/nsb for additional information.
> >
> > On Fri, 28 Feb 2025 17:44:04 +0800
> > Yang Ming <ming.1.yang at nokia-sbell.com> wrote:
> >  
> >> This change ensures that the current process is checked for
> >> being run with 'setarch' before verifying the value of
> >> '/proc/sys/kernel/randomize_va_space'. The '-R' or
> >> '--addr-no-randomize' parameter of the 'setarch' command is used
> >> to disable the randomization of the virtual address space.
> >>
> >> Fixes: af75078fece3 ("first public release")
> >> Cc: stable at dpdk.org
> >>
> >> Signed-off-by: Yang Ming <ming.1.yang at nokia-sbell.com>  
> > Looks good, I wonder if the personality() check can supersede the need
> > to reference sysfs here?
> >  
> Hi Stephen,
> 
> Thank you for your feedback. The personality() check is indeed a useful 
> addition to determine if the current process is executed with the 
> ADDR_NO_RANDOMIZE flag set, which can disable ASLR (Address Space Layout 
> Randomization).
> 
> However, relying solely on the personality() check may not be sufficient 
> in all scenarios. The personality() function checks the attributes of 
> the current process, but it does not provide information about the 
> system-wide ASLR settings, which are typically controlled via sysfs 
> (/proc/sys/kernel/randomize_va_space). The sysfs file 
> RANDOMIZE_VA_SPACE_FILE indicates the global ASLR setting for the entire 
> system, which can affect all processes.
> 
> By including both checks, we ensure comprehensive coverage:
> 1. The personality() check verifies if the current process has ASLR 
> disabled.
> 2. The sysfs reference checks the global ASLR setting, which affects all 
> processes.
> 
> Therefore, while the personality() check is valuable, it does not 
> entirely supersede the need to reference sysfs. Both checks together 
> provide a more robust determination of ASLR status.
> 
> 
> Brs,
> Yang Ming

I wonder if EAL should have --no-aslr flag and call personality itself?
Maybe not since it would have to happen early before other areas are mapped.