Be more restrictive when finding file names for libraries that need patching....

sandbox/linux/seccomp/sandbox.cc

 #include "library.h"
 #include "sandbox_impl.h"
 #include "syscall_table.h"
 
 namespace playground {
 
 // Global variables
 int                           Sandbox::proc_self_maps_ = -1;
 enum Sandbox::SandboxStatus   Sandbox::status_ = STATUS_UNKNOWN;
 int                           Sandbox::pid_;
@@ skipping 456 matching lines @@
         library->makeWritable(true);
         library->patchSystemCalls();
         library->makeWritable(false);
         break;
       }
     }
 
     // Intercept system calls in libraries that are known to have them.
     for (Maps::const_iterator iter = maps.begin(); iter != maps.end(); ++iter){
       Library* library = *iter;
+      const char* mapping = iter.name().c_str();
+
+      // Find the actual base name of the mapped library by skipping past any
+      // SPC and forward-slashes. We don't want to accidentally find matches,
+      // because the directory name included part of our well-known lib names.
+      //
+      // Typically, prior to pruning, entries would look something like this:
+      // 08:01 2289011 /lib/libc-2.7.so

[Markus (顧孟勤), 2010/02/24 01:43:08]

Is this better? I hope this makes sense now.

[agl, 2010/02/24 01:58:16]

Oh, yea. I just had the path in mind. Makes sense now.

Now my only concern is that strrchr can return NULL if the given char isn't
found. I guess all these paths are absolute, so will start with a / if nothing
else. If you're happy that "[vdso]" or "" doesn't slip in here, then LGTM.

[Markus (顧孟勤), 2010/02/24 02:02:11]

It's explicitly supposed to be able to deal with strings that don't contain any
of the delimiters. If strrchr() returns NULL, we will leave "mapping" unchanged.
Did I miss anything?

[agl, 2010/02/24 02:04:23]

No I'm just a muppet. You should commit this before I 'review' it any more :) 

+      for (const char *delim = " /"; *delim; ++delim) {
+        const char* skip = strrchr(mapping, *delim);
+        if (skip) {
+          mapping = skip + 1;
+        }
+      }
+
       for (const char **ptr = libs; *ptr; ptr++) {
-        const char *name = strstr(iter.name().c_str(), *ptr);
-        if (name) {
+        const char *name = strstr(mapping, *ptr);
+        if (name == mapping) {
           char ch = name[strlen(*ptr)];
           if (ch < 'A' || (ch > 'Z' && ch < 'a') || ch > 'z') {
             if (library->parseElf()) {
               library->makeWritable(true);
               library->patchSystemCalls();
               library->makeWritable(false);
               break;
             }
           }
         }
@@ skipping 10 matching lines @@
   // Creating the trusted thread enables sandboxing
   createTrustedThread(processFdPub_, cloneFdPub_, secureMem);
 
   // We can no longer check for sandboxing support at this point, but we also
   // know for a fact that it is available (as we just turned it on). So update
   // the status to reflect this information.
   status_ = STATUS_ENABLED;
 }
 
 } // namespace