tools/cred_dump_backtraces.c

   1 /* quick and dirty hack to grab credential backtrace info from kernel via sysctl.
   2  * sysctl is only defined if xnu is built with DEBUG_CRED defined.
   3  * The current version of this is used to target a specific credential and gather
   4  * backtrace info on all references and unreferences.
   5  */
   6
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9 #include <fcntl.h>
  10 #include <limits.h>
  11 #include <string.h>
  12 #include <errno.h>
  13 #include <unistd.h>
  14 #include <sys/stat.h>
  15 #include <sys/types.h>
  16 #include <sys/sysctl.h>
  17 #include <bsm/audit.h>
  18
  19 /* bad!  this is replicated in kern_credential.c.  make sure they stay in sync!
  20  * Or better yet have commone header file?
  21  */
  22 #define MAX_STACK_DEPTH 8
  23 struct cred_backtrace {
  24         int                             depth;
  25         uint32_t                stack[ MAX_STACK_DEPTH ];
  26 };
  27 typedef struct cred_backtrace cred_backtrace;
  28
  29 struct cred_debug_buffer {
  30         int                             next_slot;
  31         cred_backtrace  stack_buffer[ 1 ];
  32 };
  33 typedef struct cred_debug_buffer cred_debug_buffer;
  34
  35
  36 main( int argc, char *argv[] )
  37 {
  38         int                             err, i, j;
  39         size_t                  len;
  40     char                        *my_bufferp = NULL;
  41         cred_debug_buffer       *bt_buffp;
  42         cred_backtrace          *btp;
  43
  44         /* get size of buffer we will need */
  45         len = 0;
  46     err = sysctlbyname( "kern.cred_bt", NULL, &len, NULL, 0 );
  47         if ( err != 0 ) {
  48                 printf( "sysctl failed  \n" );
  49                 printf( "\terrno %d - \"%s\" \n", errno, strerror( errno ) );
  50                 return;
  51         }
  52
  53         /* get a buffer for our back traces */
  54         my_bufferp = malloc( len );
  55         if ( my_bufferp == NULL ) {
  56                 printf( "malloc error %d - \"%s\" \n", errno, strerror( errno ) );
  57                 return;
  58         }
  59     err = sysctlbyname( "kern.cred_bt", my_bufferp, &len, NULL, 0 );
  60         if ( err != 0 ) {
  61                 printf( "sysctl 2 failed  \n" );
  62                 printf( "\terrno %d - \"%s\" \n", errno, strerror( errno ) );
  63                 return;
  64         }
  65
  66         bt_buffp = (cred_debug_buffer *) my_bufferp;
  67         btp = &bt_buffp->stack_buffer[ 0 ];
  68
  69         printf("number of traces %d \n", bt_buffp->next_slot);
  70         for ( i = 0; i < bt_buffp->next_slot; i++, btp++ ) {
  71                 printf("[%d] ", i);
  72                 for ( j = 0; j < btp->depth; j++ ) {
  73                         printf("%p ", btp->stack[ j ]);
  74                 }
  75                 printf("\n");
  76         }
  77
  78         return;
  79 }
  80