[Bug dynamic-link/25114] New: RFE: Provide dlopen API(s) that allows caller to identify resolution scope (required by ASAN).

["carlos at redhat dot com" <sourceware-bugzilla at sourceware dot org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=25114

            Bug ID: 25114
           Summary: RFE: Provide dlopen API(s) that allows caller to
                    identify resolution scope (required by ASAN).
           Product: glibc
           Version: 2.31
            Status: NEW
          Severity: normal
          Priority: P2
         Component: dynamic-link
          Assignee: unassigned at sourceware dot org
          Reporter: carlos at redhat dot com
  Target Milestone: ---

The ASAN interposer for dlopen cannot accurately interpose dlopen because when
it itself calls dlopen the dynamic loader considers ASAN to be the caller and
the scope resolution for loading the library starts there. Instead what you
want is for ASAN to be able to call dlopen but with the search scope of the
library it is interposing, which may not even be known. Either way, we need
some new kind of API here.

The following example shows the situation:

#include <dlfcn.h>
#include <iostream>
int main()
{
    void *handle = dlopen("libb.so", RTLD_NOW);
    if (handle == NULL) {
        std::cout << "Failed to load libb.so" << std::endl;
    }
}

#mkdir lib
#g++ --sanitize=address -Wl,-rpath='$ORIGIN/lib' -Wl,--enable-new-dtags -ldl -o
main main.cpp
#cd lib; 

Create libb.so: 
int foo()
{
  return 1;
}

g++ -fPIC -shared b.C -o libb.so

Actual results:

strace ./main 2>&1 | grep libb.so
open("/opt/rh/devtoolset-6/root/usr/lib/../lib64/tls/libb.so",
O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
:
<snipped>
:
open("/usr/lib64/libb.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or
directory)
write(1, "Failed to load libb.so\n", 23Failed to load libb.so

Expected results:

strace ./main 2>&1 | grep libb.so

open("/opt/rh/devtoolset-6/root/usr/lib64/tls/libb.so", O_RDONLY) = -1 ENOENT
(No such file or directory)

open("/root/cc/lib/libb.so", O_RDONLY)  = 3

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