hook_uname.c

// date: 2023-06-12
// license: GPLv3 https://www.gnu.org/licenses/gpl-3.0.txt
// author: nanpuyue <[email protected]> https://blog.nanpuyue.com
// build: gcc -fPIC -shared -o hook_uname.so hook_uname.c -ldl
// usage: LD_PRELOAD=./hook_uname.so uname -a

#include <string.h>
#include <dlfcn.h>
#include <sys/utsname.h>

typedef int (*uname_t) (struct utsname *);

int uname(struct utsname *buf) {
    static uname_t _uname = NULL;
    if(!_uname) {
        _uname = (uname_t) dlsym(RTLD_NEXT, "uname");
        if (!_uname) {
            return -1;
        }
    }

    int ret = _uname(buf);
    if (!ret) {
        strncpy(buf->version, "custom_version", 15);
        strncpy(buf->release, "5.15.0", 7);
    }

    return ret;
}