Applications relying on parsing `libc.so.6` will not work

[liushuyu]

There are some native Linux applications that parse libc.so.6, which will not currently work with box64.

One application uses this as an anti-tampering technique; the application will still work fine with qemu (which indicates the intention of this anti-tampering was probably not to stop emulations).

I have approximated their implementation here: https://godbolt.org/z/W9fbM534G

[yzewei]

Good Idea.

[ksco]

What good idea?

[ksco]

For the record, a dirty way to workaround:

First, make a fake mini libc (just for demo, one needs to implement those functions, apparently):

    .text

	.globl  strerrordesc_np
strerrordesc_np:
	nop
	nop
	nop

	.globl syscall
syscall:
	nop
	nop
	nop

Compile it with

gcc -c myminilibc.S
gcc -shared -fPIC myminilibc.o -o myminilibc.so

Then, the following patch is needed to bypass the RTLD_NEXT restriction:

diff --git a/src/librarian/librarian.c b/src/librarian/librarian.c
index f33ddff54..e46dba6c0 100644
--- a/src/librarian/librarian.c
+++ b/src/librarian/librarian.c
@@ -468,7 +468,7 @@ int GetNextSymbolStartEnd(lib_t *maplib, const char* name, uintptr_t* start, uin
 {
     assert(self);   // need self for this one
     int weak = 0;
-    int next = 0;
+    int next = 1;
     void* sym;
     // search in needed libs from preloaded first, in order
     if(my_context->preload)

Run

BOX64_LD_PRELOAD=myminilibc.so box64 ./program

[ksco]

Not saying this is the correct way to solve this, but I hope it clarifies the cause.