libsgxstep: Fix bug in /proc/self/maps parsing for enclave discovery.

Fixes #54
jovanbulck · Oct 1, 2022 · d53ab9b · d53ab9b
1 parent c09a1b9
commit d53ab9b
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Showing 3 changed files with 17 additions and 6 deletions.
diff --git a/libsgxstep/config.h b/libsgxstep/config.h
@@ -21,6 +21,8 @@
 #ifndef SGX_STEP_CONFIG
 #define SGX_STEP_CONFIG
 
+#define DEBUG                       0
+
 #define PSTATE_PCT                  100
 #define SINGLE_STEP_ENABLE          1
 #define USER_IDT_ENABLE             1

diff --git a/libsgxstep/debug.h b/libsgxstep/debug.h
@@ -25,6 +25,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdint.h>
+#include "config.h"
 
 #if !NO_SGX
 #include <sgx_error.h>
@@ -55,6 +56,13 @@ extern sgx_status_t sgx_step_rv;
         fflush(stdout);                                                 \
     } while(0)
 
+#if DEBUG
+    #define debug(msg, ...)     info("DEBUG: " msg, ##__VA_ARGS__)
+#else
+    #define debug(msg, ...)
+#endif
+
+
 #if LIBSGXSTEP_SILENT
     #define libsgxstep_info(msg, ...)
 #else

diff --git a/libsgxstep/enclave.c b/libsgxstep/enclave.c
@@ -59,6 +59,7 @@ void register_enclave_info(void)
 
     /* Parse /proc/self/maps to detect any enclaves mapped in the address space.
      * Expected format: "start-end perms offset dev inode optional_pathname"
+     * For documentation of /proc/pid/maps, see `man 5 proc`.
      *
      * NOTES: - victim.tcs is set by the patched untrusted runtime on first
      *          enclave entry (e.g., as part of sgx_create_enclave)
@@ -67,25 +68,25 @@ void register_enclave_info(void)
      *        - only supports a single enclave that is expected to be
      *          contiguously mapped in the address space
      */
-    #if 0
-        info("cat /proc/self/maps");
+    #if DEBUG
+        debug("cat /proc/self/maps");
         char command[256];
         sprintf(command, "cat /proc/%d/maps", getpid());
         system(command);
+        debug("------");
     #endif
     ASSERT((fd_self_maps = fopen("/proc/self/maps", "r")) >= 0);
-    while (fscanf(fd_self_maps, "%lx-%lx %*s %*x %*d:%*d %*[0-9 ]%m[^\n]",
+    while (fscanf(fd_self_maps, "%lx-%lx %*s %*x %*x:%*x %*[0-9 ]%m[^\n]",
                   &start, &end, &pathname) > 0)
     {
-        //info("%p - %p %s", (void*) start, (void*) end, pathname);
+        debug("%p - %p %s", (void*) start, (void*) end, pathname);
         is_isgx = (pathname != NULL) && strstr(pathname, "/dev/isgx") != NULL;
         is_kern = (pathname != NULL) && strstr(pathname, "/dev/sgx_enclave") != NULL;
         is_enclave = is_isgx || is_kern;
 
         if (is_enclave && !prev_is_enclave && !victim.base)
         {
-            //info("Found %s enclave at %p in /proc/self/maps", pathname, (void*) start);
-            //ASSERT( !victim.base && "multiple enclaves found in /proc/self/maps");
+            debug("Found %s enclave at %p in /proc/self/maps", pathname, (void*) start);
             victim.base = (uint64_t) start;
             victim.drv = is_isgx ? "/dev/isgx" : "/dev/sgx_enclave";
         }