chore: Update faq.md with cargo install explanation and add avoid car…

…go install in build.rs

book/src/faq.md

@@ -2,6 +2,12 @@
 
 This page contains known issues and solutions for RootAsRole project.
 
+## Why I cannot do `cargo install rootasrole` command ?
+
+The `cargo install` command is primarily designed to install Rust binaries into a user’s local environment, specifically into the `.cargo/bin` directory in the user’s home directory. The philosophy behind this is to keep the installation process simple and unprivileged, avoiding system-wide changes that would require root or admin permissions.
+
+In this context, RootAsRole is a privilege escalation tool, so it requires privileges to work. As the `cargo install` command is not designed to install system-wide binaries, so RootAsRole won't work as expected this way.
+
 ## capable does not work on my OS, what can I do ?
 
 capable is a tool based on eBPF features, so it requires a Linux kernel version 4.1 or later. Additionnally you need many kernel features enabled, [described here](https://github.com/iovisor/bcc/blob/master/INSTALL.md#kernel-configuration). It is also, possible that the program cannot allocate memory, in this case you may consider to add CAP_SYS_RESOURCE capability to the program, but this may not solve completely the issue.

build.rs

@@ -3,6 +3,7 @@ use std::error::Error;
 use std::fs::{self, File};
 use std::io::{BufRead, BufReader, Write};
 use std::path::Path;
+use std::process::Command;
 
 
 fn package_version(json: &Value) -> Result<&str, Box<dyn Error>> {
@@ -63,6 +64,11 @@ fn main() {
     println!("cargo:rerun-if-changed=resources/rootasrole.json");
     println!("cargo:rerun-if-changed=build.rs");
 
+    let is_install = std::env::var("CARGO_INSTALL_ROOT").is_ok();
+    if is_install {
+        panic!("This crate is not meant to be installed with cargo install, please download .deb or .rpm and install it with your package manager.\nSee: https://lechatp.github.io/RootAsRole/faq.html");
+    }
+
     let json: Value = include_str!("resources/rootasrole.json")
         .parse()
         .expect("Failed to parse rootasrole.json");
@@ -71,6 +77,7 @@ fn main() {
     if dest_path.exists() && fs::read_to_string(&dest_path).unwrap().ends_with(&format!("\"{}\";\n",package_version)) {
         return;
     }
+
     let mut f = File::create(dest_path).unwrap();
     f.write_all(b"// This file is generated by build.rs\n")
         .unwrap();