[PATCH] eal/linux: enhance ASLR verification

[PATCH] eal/linux: enhance ASLR verification

[Yang Ming]

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@dpdk.org

Signed-off-by: Yang Ming <ming.1.yang@nokia-sbell.com>
---
 lib/eal/linux/eal_memory.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/lib/eal/linux/eal_memory.c b/lib/eal/linux/eal_memory.c
index 9dda60c0e1..ab1fd83cf2 100644
--- a/lib/eal/linux/eal_memory.c
+++ b/lib/eal/linux/eal_memory.c
@@ -15,6 +15,7 @@
 #include <sys/stat.h>
 #include <sys/file.h>
 #include <sys/resource.h>
+#include <sys/personality.h>
 #include <unistd.h>
 #include <limits.h>
 #include <signal.h>
@@ -26,7 +27,6 @@
 #include <numa.h>
 #include <numaif.h>
 #endif
-
 #include <rte_errno.h>
 #include <rte_log.h>
 #include <rte_memory.h>
@@ -200,6 +200,14 @@ static int
 aslr_enabled(void)
 {
 	char c;
+
+	/*
+	 * check whether the current process is executed with command line
+	 * "setarch ... --addr-no-randomize ...".
+	 */
+	if ((personality(0xffffffff) & ADDR_NO_RANDOMIZE) == ADDR_NO_RANDOMIZE)
+		return 0;
+
 	int retval, fd = open(RANDOMIZE_VA_SPACE_FILE, O_RDONLY);
 	if (fd < 0)
 		return -errno;
-- 
2.34.1

Re: [PATCH] eal/linux: enhance ASLR verification

[Stephen Hemminger]

On Fri, 28 Feb 2025 17:44:04 +0800
Yang Ming <ming.1.yang@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@dpdk.org
> 
> Signed-off-by: Yang Ming <ming.1.yang@nokia-sbell.com>

Looks good, I wonder if the personality() check can supersede the need
to reference sysfs here?

Re: [PATCH] eal/linux: enhance ASLR verification

[Yang Ming]

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@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@dpdk.org
>>
>> Signed-off-by: Yang Ming <ming.1.yang@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

Re: [PATCH] eal/linux: enhance ASLR verification

[Stephen Hemminger]

On Fri, 28 Feb 2025 17:44:04 +0800
Yang Ming <ming.1.yang@nokia-sbell.com> wrote:

> @@ -26,7 +27,6 @@
>  #include <numa.h>
>  #include <numaif.h>
>  #endif
> -
>  #include <rte_errno.h>
>  #include <rte_log.h>
>  #include <rte_memory.h>

Best to keep blank line there

Re: [PATCH] eal/linux: enhance ASLR verification

[Stephen Hemminger]

On Wed, 12 Mar 2025 11:13:27 +0800
Yang Ming <ming.1.yang@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@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@dpdk.org
> >>
> >> Signed-off-by: Yang Ming <ming.1.yang@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.