Fwd: how to check the hardware support of XN/XI bit support on ARM/MIPS platform

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* Fwd: how to check the hardware support of XN/XI bit support on ARM/MIPS platform
       [not found] <CALTRzTn_2eaE7vr-tXwGKmO3fGqmif0hdrFEinQjbf6Dx=yHCg@mail.gmail.com>
@ 2013-01-04  6:02 ` Girish garg
  2013-01-08 14:25   ` Russell King - ARM Linux
  0 siblings, 1 reply; 2+ messages in thread
From: Girish garg @ 2013-01-04  6:02 UTC (permalink / raw)
  To: linux-arm-kernel

Dear All,


Please let me know how to check the hardware support of XN/XI bit support
on ARM/MIPS platform.

As there is support of XN bit on ARM v >= 6 (I was using ARM 6), but no
support on MIPS (*MIPS 34Kc)*.

To check the hardware support , I run the paxtest i.e execstack. The
execstack test program must crash on ARM, but not on MIPS.

*But It is crashing on both ARM and MIPS.*

Please let me know how I can prove/check the hardware support of XN bit in
arm platform.



/* *execstack.c* - Tests wether code on the stack can be executed

 *

*/

#include <stdlib.h>

#include <stdio.h>

#include <sys/mman.h>

#include <unistd.h>

#include <errno.h>

#include <limits.h>

#include <signal.h>

#include <sys/types.h>

#include <sys/wait.h>



#ifndef PAGESIZE

#define PAGESIZE        (4096)

#endif /* PAGESIZE */



typedef void (*fptr)(void);

char *testname = "Executable stack                         ";



void itworked( void )

{

        printf( "Vulnerable\n" );

        exit( 1 );

}



void doit( void )

{

        char buf[8192];

        fptr func;



        /* Put a RETN instruction in the buffer */

        buf[0] = '\xc3';



        /* Convert the pointer to a function pointer */

        func = (fptr)buf;



        /* Call the code in the buffer */

        func();



        /* It worked when the function returns */

        itworked();

}



int main( int argc, char *argv[] )

{

        int status;



        printf( "%s: ", testname );

        fflush( stdout );



        if( fork() == 0 ) {

                do_mprotect((unsigned long)argv & ~4095U, 4096,
PROT_READ|PROT_WRITE|PROT_EXEC);

                doit();

        } else {

                wait( &status );

                if( WIFEXITED(status) == 0 ) {

                        printf( "Killed\n" );

                        exit( 0 );

                }

        }



        exit( 0 );

}


void itfailed( void )

{

        printf( "Ok\n" );

        exit( 2 );

}

int do_mprotect( const void *addr, size_t len, int prot )

{

        void *ptr;

        int retval;

        /* Allign to a multiple of PAGESIZE, assumed to be a power of two */

        ptr = (char *)(((unsigned long) addr) & ~(PAGESIZE-1));

         retval = mprotect( ptr, len, prot );

        if( retval != 0 && errno == EINVAL ) {

                perror( "could not mprotect():" );

                exit( 1 );

        }

         return retval;

}



*On MIPS target the execstack testcase giving below coredump although I
assume that XI bit is not supported in MIPS.
*

*To check the XI bit support on MIPS target I read the bit No 12 i.e RXI of
Config 3 register.*

The value of config3 register is *0x2425 *in MIPS kernel (X13).

Followings are the bit wise representation:

* *

Position

31















24















16





13





10









5





2



0

Value

0

* *

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

*1*

0

0

*1*

0

0

0

0

*1*

0

0

*1*

0

*1*

* *


**


****






VDLinux#> ./execstack

Executable stack[   53.272000] do_ri() : sending SIGILL to execstack,
PID:386

                [   53.280000]
================================================================================

[   53.288000]  KERNEL Version : 0045, debug

[   53.292000]
================================================================================

[   53.300000]

[   53.304000]
--------------------------------------------------------------------------------------

[   53.312000] EPC, RA MEMINFO

[   53.316000]
--------------------------------------------------------------------------------------

[   53.324000] epc:7f9c9548, ra:400854

[   53.328000]
--------------------------------------------------------------------------------------

[   53.336000] EPC meminfo (0x7f9c9148 to 0x7f9c9548)

[   53.340000] 9140:                   00000000 00000000 00000000 00000000
00000000 00000000

[   53.348000] 9160: 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000

[   53.360000] 9180: 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000

---- SKIP ---

[   53.616000] 9540: 00000000 00000000 ffffffff


[   53.624000]
--------------------------------------------------------------------------------------

[   53.636000] RA meminfo (0x00400054 to 0x00400854)

[   53.640000] 0040:                                              00000003
00000154 00400154

[   53.648000] 0060: 00400154 0000000d 0000000d 00000004 00000001 70000000
00000184 00400184

[   53.656000] 0080: 00400184 00000018 00000018 00000004 00000004 00000001
00000000 00400000

 [   53.692000] 0100: 00400164 00000020 00000020 00000004 00000004 6474e550
00000aac 00400aac

[   53.700000] 0120: 00400aac 00000034 00000034 00000004 00000004 00000000
00000000 00000000

--SKIP --

 [   53.888000] 03e0: 001b0011 00000035 00000000 00000000 00000012 000000a0
00400568 00000000

[   53.896000] 0400: 000c0012 00000001 00000000 00000000 00000022 675f5f00
5f6e6f6d 72617473

 [   54.200000]
--------------------------------------------------------------------------------------

[   54.208000]

[   54.208000] Cpu 0

[   54.212000] $ 0   : 00000000 00000001 00000000 00000001

[   54.216000] $ 4   : 7f9ca000 00001000 00000007 00000000

[   54.224000] $ 8   : 00000000 80000008 800ebe90 fffffff8

[   54.228000] $12   : 20202020 2af76000 00000000 7f9c9e20

[   54.232000] $16   : 7f9ca0e4 00000000 00580000 00d584a8

[   54.240000] $20   : 00590e05 00d5933c 005b0000 00000000

[   54.244000] $24   : 00000000 7f9c7fd8

[   54.248000] $28   : 2c1b6980 7f9c7fc0 00000000 00400854

[   54.256000] Hi    : 00000308

[   54.256000] Lo    : 0001e624

[   54.260000] epc   : 7f9c9548 0x7f9c9548

[   54.264000]     Tainted: P

[   54.268000] ra    : 00400854 0x400854

[   54.272000] Status: 01008c13    USER EXL IE

[   54.276000] Cause : 10800028

[   54.280000] PrId  : 00019555 (MIPS 34Kc)

[   54.284000] -----------------------------------------------------------

[   54.292000] * dump maps on pid (386)

[   54.296000] -----------------------------------------------------------

[   54.300000] 00400000-00401000 r-xp 00000000 08:01 353
/dtv/usb/sda1/pax_test_mips/execstack

[   54.312000] 00410000-00411000 rw-p 00000000 08:01 353
/dtv/usb/sda1/pax_test_mips/execstack

[   54.320000] 2af76000-2af88000 rw-p 00000000 00:00 0

[   54.324000] 2c000000-2c021000 r-xp 00000000 8a:0a 67
/mtd_exe/lib/ld-2.14.1.so

[   54.332000] 2c030000-2c031000 r--p 00020000 8a:0a 67
/mtd_exe/lib/ld-2.14.1.so

[   54.340000] 2c031000-2c032000 rw-p 00021000 8a:0a 67
/mtd_exe/lib/ld-2.14.1.so

[   54.348000] 2c040000-2c19b000 r-xp 00000000 8a:0a 71
/mtd_exe/lib/libc-2.14.1.so

[   54.356000] 2c19b000-2c1aa000 ---p 0015b000 8a:0a 71
/mtd_exe/lib/libc-2.14.1.so

[   54.368000] 2c1aa000-2c1ae000 r--p 0015a000 8a:0a 71
/mtd_exe/lib/libc-2.14.1.so

[   54.376000] 2c1ae000-2c1b0000 rw-p 0015e000 8a:0a 71
/mtd_exe/lib/libc-2.14.1.so

[   54.384000] 2c1b0000-2c1b3000 rw-p 00000000 00:00 0

[   54.388000] 7f9a9000-7f9cb000 rwxp 00000000 00:00 0          [stack]

[   54.396000] 7fff7000-7fff8000 r-xp 00000000 00:00 0          [vdso]

[   54.400000] -----------------------------------------------------------

[   54.400000]

[   54.408000] task stack info : pid(386) stack area (0x7f9a9000 ~
0x7f9cb000)

[   54.416000] -----------------------------------------------------------

[   54.424000] * dump user stack

[   54.428000] -----------------------------------------------------------

[   54.432000] dump user stack(0x7f9c7fc0 to 0x7f9c9f78)

[   54.440000] 7fc0: 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000

[   54.448000] 7fe0: 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000

--- SKIP ---

 [   55.884000] 94c0: 00000000 00000000 00000000 00000000 00000000 00000000
00000000 00000000

 [   55.912000] 9520: 00000000 00000000 2c039000 00000000 00000000 2c007458
00000000 00000000

[   55.920000] 9540: 00000000 00000000 ffffffff 00000000 00000000 00000000
00000000 00000000

--- SKIP ---

 [   56.600000] 9f20: 00000000 00000000 00000000 00000000 00410bbc 00d584a8
00590e05 00d5933c

[   56.608000] 9f40: 005b0000 00000000 00000000 2c00fea8 00410be0 00d584a8
00590e05 2af7628c

[   56.616000] 9f60: 2af76a70 00000001 00000001 00000000 2c039000 00d5933c
2c04a2bc

[   56.624000] -----------------------------------------------------------

[   56.624000]

[   56.636000] ##### send signal from KERNEL, SIG : 4, execstack, PID:386,
force_sig_info

[   56.644000] Call Trace:

[   56.644000] [<802fccd8>] dump_stack+0x8/0x34 from[<80044180>]
force_sig_info+0x54/0x1b0

[   56.652000] [<80044180>] force_sig_info+0x54/0x1b0 from[<80007364>]
ret_from_exception+0x0/0x10

[   56.664000]

[   56.664000] ##### send signal SIG : 4, execstack(386)->execstack(386)
__send_signal

[   56.672000] ##### deliver signal SIG : 4, execstack(386)
get_signal_to_deliver

[   56.680000] [VDLP COREDUMP] SIGNR:4

[   56.680000]

[   56.684000] ***** Coredump : Insert USB memory stick, mount check per
10sec... *****

[   57.724000] ***** USB detected *****

[   57.728000] ***** Create pid : 386 coredump file to USB mount dir
/dtv/usb/sda1/Coredump.386.gz ******

[   57.736000] * Ultimate CoreDump v1.0 : started dumping core into
'Coredump.386.gz' file *

[   57.744000] <1>##### elf aligned pages num : 1 + (3 Coredump guard
buffers)

[   57.752000] ##### Not used first lower guard page, elf_foffset : 1364,
aligned_elf_foffset : 4096

[   57.764000] ##### set_gzip_header() return success...

[   57.768000] ##### Allocated 267980 bytes for deflate workspace

[   57.776000] ##### coredump_alloc_workspaces() return success...

[   57.980000] ##### (vma->vm_next) == NULL ...

[   57.992000]  ##### Process addr space debug Info #####

[   57.996000]  ##### vma_cnt : 13

[   58.000000]  ##### vm_page : 65

[   58.004000]  ##### user_page_cnt : 17

[   58.008000]  ##### zero_page_cnt : 48

[   58.012000]  ##### kernel_page_cnt : 0

[   58.016000] ##### uncomp_coredump_file_size : 270336

[   58.020000] ##### GZIP tailer CRC32 : 2982301179

[   58.028000] ***** Create coredump file to USB mount dir ******

[   58.032000] CoreDump: finished dumping core

         : Killed




 *Similarly for ARM also it is giving core dump like this:*

VDLinux#> ./execstack

Executable stack[  451.784000] execstack: unhandled page fault (11) at
0xbead5860, code 0x80000007

[  451.792000]
================================================================================

[  451.800000]  KERNEL Version : 0000

[  451.804000]
================================================================================

[  451.812000]

[  451.812000]
--------------------------------------------------------------------------------------

[  451.820000] PC, LR MEMINFO

[  451.824000]
--------------------------------------------------------------------------------------

[  451.832000] PC:bead5860, LR:85c0

[  451.836000]
--------------------------------------------------------------------------------------

[  451.844000] PC meminfo (0xbead5460 to 0xbead5c60)

[  451.848000] 5460: ???????? ???????? ???????? ???????? ???????? ????????
???????? ????????

--- SKIP --

 [  452.524000] 7fe0: ???????? ???????? ???????? ???????? ???????? ????????
???????? ????????

[  452.532000] 8000: 464c457f 00010101 00000000 00000000 00280002 00000001
00008500 00000034

--- SKIP ---

 [  453.156000] 8980: 04000000 0000001d 00841901 05010000 0086b403 004f0500
14000000 02000001

[  453.164000] 89a0: 00004200 9a010400 01000000 000000da 00000043 00008644
000086ac 00000027

[  453.172000]
--------------------------------------------------------------------------------------

[  453.180000]

[  453.180000] pgd = e317c000

[  453.184000] [bead5860] *pgd=a9d2e831, *pte=00000000, *ppte=00000000

[  453.192000]

[  453.192000] Pid: 429, comm:            execstack

[  453.196000] CPU: 1    Tainted: P             (3.0.33 #124)

[  453.200000] PC is at 0xbead5860

[  453.204000] LR is at 0x85c0

[  453.208000] pc : [<bead5860>]    lr : [<000085c0>]    psr: 60000010

[  453.208000] sp : bead5860  ip : 40220f80  fp : 00000000

[  453.220000] r10: 40119000  r9 : 00000000  r8 : 00000000

[  453.224000] r7 : 00000000  r6 : 00008500  r5 : 00000000  r4 : bead79c4

[  453.232000] r3 : bead5860  r2 : 00000007  r1 : 00001000  r0 : 00000000

[  453.236000] Flags: nZCv  IRQs on  FIQs on  Mode USER_32  ISA ARM  Segment
user

[  453.244000] Control: 10c53c7d  Table: a9d7c04a  DAC: 00000015

[  453.252000] [<c004b034>] (show_regs+0x0/0x58) from [<c004e588>]
(show_info+0xb0/0x104)

[  453.260000]  r4:e38e4ba0 r3:00000002

[  453.260000] [<c004e4d8>] (show_info+0x0/0x104) from [<c0055468>]
(__do_user_fault+0x50/0x94)

[  453.272000]  r6:0000000b r5:bead5860 r4:e38e4ba0 r3:00000000

[  453.276000] [<c0055418>] (__do_user_fault+0x0/0x94) from [<c03bf93c>]
(do_page_fault+0x2d8/0x324)

[  453.284000]  r7:e38e4ba0 r6:bead5860 r5:00030002 r4:e31c7fb0

[  453.292000] [<c03bf664>] (do_page_fault+0x0/0x324) from [<c003b260>]
(do_PrefetchAbort+0x44/0xa8)

[  453.300000] [<c003b21c>] (do_PrefetchAbort+0x0/0xa8) from [<c03bd6c8>]
(ret_from_exception+0x0/0x10)

[  453.308000] Exception stack(0xe31c7fb0 to 0xe31c7ff8)

[  453.312000] 7fa0:                                     00000000 00001000
00000007 bead5860

[  453.320000] 7fc0: bead79c4 00000000 00008500 00000000 00000000 00000000
40119000 00000000

[  453.328000] 7fe0: 40220f80 bead5860 000085c0 bead5860 60000010 ffffffff

[  453.336000]  r7:00000000 r6:00008500 r5:00000007 r4:0000040f

[  453.344000] -----------------------------------------------------------

[  453.348000] * dump maps on pid (429)

[  453.352000] -----------------------------------------------------------

[  453.360000] 00008000-00009000 r-xp 00000000 08:11 440
/dtv/usb/sdb1/paxtest-0.9.5/execstack

[  453.368000] 00010000-00011000 rw-p 00000000 08:11 440
/dtv/usb/sdb1/paxtest-0.9.5/execstack

[  453.376000] 400bc000-400bd000 rw-p 400bc000 08:11 440

[  453.380000] 400ce000-400cf000 rw-p 400ce000 08:11 440

[  453.384000] 400f2000-40110000 r-xp 00000000 b3:03 105 /mtd_exe/lib/
ld-2.14.1.so

[  453.392000] 40118000-40119000 r--p 0001e000 b3:03 105 /mtd_exe/lib/
ld-2.14.1.so

[  453.400000] 40119000-4011a000 rw-p 0001f000 b3:03 105 /mtd_exe/lib/
ld-2.14.1.so

[  453.408000] 4011c000-4011d000 rw-p 4011c000 b3:03 105

[  453.412000] 4015d000-40277000 r-xp 00000000 b3:03 113 /mtd_exe/lib/
libc-2.14.1.so

[  453.420000] 40277000-4027f000 ---p 0011a000 b3:03 113 /mtd_exe/lib/
libc-2.14.1.so

[  453.428000] 4027f000-40281000 r--p 0011a000 b3:03 113 /mtd_exe/lib/
libc-2.14.1.so

[  453.436000] 40281000-40282000 rw-p 0011c000 b3:03 113 /mtd_exe/lib/
libc-2.14.1.so

[  453.444000] 40282000-40285000 rw-p 40282000 b3:03 113

[  453.448000] beab6000-bead7000 rw-p befde000 b3:03 113

[  453.452000] bead7000-bead8000 rwxp befff000 b3:03 113

[  453.460000] ffff0000-ffff1000 r-xp ffff0000 b3:03 113

[  453.464000] -----------------------------------------------------------

[  453.464000]

[  453.472000] task stack info : pid(429) stack area (0xbead7000 ~
0xbead8000)

[  453.480000] -----------------------------------------------------------

[  453.484000] * dump user stack

[  453.488000] -----------------------------------------------------------

[  453.496000] pid(429) : seems stack overflow.

[  453.496000]   sp(bead5860), stack vma (0xbead7000 ~ 0xbead8000)

[  453.504000] -----------------------------------------------------------

[  453.504000]

[  453.512000] [VDLP COREDUMP] SIGNR:11

[  453.512000]

[  453.520000] ***** Coredump : Insert USB memory stick, mount check per
10sec... *****

[  453.528000] ***** USB detected *****

[  453.528000] ***** Create pid : 429 coredump file to USB mount dir
/dtv/usb/sdb1/Coredump.429.gz ******

[  453.540000] * Ultimate CoreDump v0.4 : started dumping core into
'Coredump.429.gz' file *

[  453.548000] <1>##### elf aligned pages num : 1 + (3 Coredump guard
buffers)

[  453.552000] ##### Not used first lower guard page, elf_foffset : 1488,
aligned_elf_foffset : 4096

[  453.564000] ##### set_gzip_header() return success...

[  453.568000] ##### Allocated 267980 bytes for deflate workspace

[  453.572000] ##### coredump_alloc_workspaces() return success...

                         : [  453.692000] ##### (vma->vm_next) == NULL ...

[  453.700000]  ##### Process addr space debug Info #####

[  453.704000]  ##### vma_cnt : 16

[  453.708000]  ##### vm_page : 47

[  453.708000]  ##### user_page_cnt : 15

[  453.712000]  ##### zero_page_cnt : 32

[  453.716000]  ##### kernel_page_cnt : 0

[  453.720000] ##### uncomp_coredump_file_size : 196608

[  453.724000] ##### GZIP tailer CRC32 : 1604686521

[  453.732000] ***** Create coredump file to USB mount dir ******

[  453.736000] CoreDump: finished dumping core

Killed



*Please let me know how to check the hardware support of XN bit in ARMv6
/ARMv7 and XI bit support on MIPS 34Kc.*

* *

Thanks and Regards,
Girish Gupta
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^ permalink raw reply	[flat|nested] 2+ messages in thread

* Fwd: how to check the hardware support of XN/XI bit support on ARM/MIPS platform
  2013-01-04  6:02 ` Fwd: how to check the hardware support of XN/XI bit support on ARM/MIPS platform Girish garg
@ 2013-01-08 14:25   ` Russell King - ARM Linux
  0 siblings, 0 replies; 2+ messages in thread
From: Russell King - ARM Linux @ 2013-01-08 14:25 UTC (permalink / raw)
  To: linux-arm-kernel

On Fri, Jan 04, 2013 at 11:32:03AM +0530, Girish garg wrote:
>         char buf[8192];
>         fptr func;
> 
>         /* Put a RETN instruction in the buffer */
>         buf[0] = '\xc3';

If you're going to be poking opcodes into the stack, you need to use
the correct opcodes for the CPU you're using.

You also need to use the correct opcodes (and alignment) for the
instruction set you're using - iow, if you're using ARM or Thumb.

0xc3 on its own is not a valid ARM or Thumb instruction.

^ permalink raw reply	[flat|nested] 2+ messages in thread

end of thread, other threads:[~2013-01-08 14:25 UTC | newest]

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2013-01-04  6:02 ` Fwd: how to check the hardware support of XN/XI bit support on ARM/MIPS platform Girish garg
2013-01-08 14:25   ` Russell King - ARM Linux

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