uid_wrapper (1)

LD_PRELOAD=libuid_wrapper.so UID_WRAPPER=1 UID_WRAPPER_ROOT=1 ./myapplication

Allows uid switching as a normal user.

Start any application making it believe it is running as root.

Support for user/group changing in the local thread using the syscalls (like glibc).

More precisely this library intercepts seteuid and related calls, and simulates them in a manner similar to the nss_wrapper and socket_wrapper libraries.

Some projects like a file server need privilege separation to be able to switch to the connection user and do file operations. uid_wrapper convincingly lies to the application letting it believe it is operating as root and even switching between UIDs and GIDs as needed.

UID_WRAPPER

If you load the uid_wrapper and enable it with setting UID_WRAPPER=1 all setuid and setgid will work, even as a normal user.

UID_WRAPPER_ROOT

It is possible to start your application as fake root with setting UID_WRAPPER_ROOT=1.

UID_WRAPPER_DEBUGLEVEL

If you need to see what is going on in uid_wrapper itself or try to find a bug, you can enable logging support in uid_wrapper if you built it with debug symbols.

0 = ERROR

1 = WARNING

2 = DEBUG

3 = TRACE

$ LD_PRELOAD=libuid_wrapper.so UID_WRAPPER=1 UID_WRAPPER_ROOT=1 id
uid=0(root) gid=0(root) groups=100(users),0(root)