fake sudo

a Script to allow normal user to launch root shell, after providing a KEY file.

In android, I don't want to root my phone, but still needs root access.

So I installed this script, instead of SuperSU.

runas.cc

#include <rlib/sys/unix_handy.hpp>
#include <rlib/opt.hpp>

int main(int argc, char **argv) {
    rlib::opt_parser args(argc, argv);
    auto keyFile = args.getValueArg("-k", false, "");

    setuid(geteuid());
    setgid(getegid());

    rlib::execs("/bin/bash", std::vector<std::string>{"runas.impl.sh", keyFile});
}

runas.impl.sh

#!/bin/bash
# Usage: 1. Generate your key file, and keep it secret. Get its SHA256 and write it down at `answer`.
#        2. Compile runas.cc, Then run the following commands as root:
#               chmod +s ./runas
#        3. Try `./runas -k ./key` as normal user.
#
# File Permissions:
# 
# -rwsr-sr-x 1 root    root    82K Apr 18 19:29 runas*
# -rw-r--r-- 1 recolic recolic 320 Apr 18 19:29 runas.cc
# ---------- 1 root    root    733 Apr 18 19:35 runas.impl.sh*


[ "$1" = "" ] && key_file_name="./key" || key_file_name="$1"
echo "Verifying '$key_file_name'..."

#### Verify key file
checksum=$(sha256sum "$key_file_name" | sed 's/ .*$//g')
answer='07ecd901c90ee7a72efdc0d7e7b47c2b8d02b5a9cfcbb9ae4f0f31561d01af04'

if [ "$checksum" = "$answer" ]; then
    bash
else
    echo 'Verification failed.'
    exit 2
fi

exit $?