initial commit

7 files changed, 556 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..96ef6c0
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+/target
+Cargo.lock
diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..e401bd5
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,326 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
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+ "winapi-x86_64-pc-windows-gnu",
+]
+
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diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..d063d87
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,14 @@
+[package]
+name = "crab"
+version = "4.2.0"
+edition = "2021"
+
+[dependencies]
+pam = "0.7.0"
+pwd = "1.4.0"
+nix = "0.25.0"
+exec = "0.3.1"
+rpassword = "7.1.0"
+serde_json = "1.0.87"
+procinfo = "0.4.2"
+time = "0.3.17"
\ No newline at end of file
diff --git a/build.sh b/build.sh
new file mode 100755
index 0000000..b9e3c57
--- /dev/null
+++ b/build.sh
@@ -0,0 +1,21 @@
+#!/bin/bash
+
+if [[ $(/usr/bin/id -u) -ne 0 ]]; then
+    echo "Please run this as root"
+    exit
+fi
+
+# Make sure rust is able to build as root
+rustup default stable
+
+# Build crab
+cargo build --release
+
+# Copy executable to bin
+cp ./target/release/crab /bin/crab
+chown root:root /bin/crab
+chmod 6755 /bin/crab
+
+# Set up config files
+cp pam /etc/pam.d/crab
+cp -n conf /etc/crab.conf
\ No newline at end of file
diff --git a/conf b/conf
new file mode 100644
index 0000000..bebb505
--- /dev/null
+++ b/conf
@@ -0,0 +1 @@
+root true
\ No newline at end of file
diff --git a/pam b/pam
new file mode 100644
index 0000000..b98216b
--- /dev/null
+++ b/pam
@@ -0,0 +1,4 @@
+#%PAM-1.0
+auth        include    system-auth
+account     include    system-auth
+session     include    system-auth
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..dd8eeb3
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,188 @@
+use std::fs;
+use std::{env, os::unix::prelude::PermissionsExt};
+use std::process::ExitCode;
+use std::time::SystemTime;
+use pwd::Passwd;
+use nix::{unistd};
+use serde_json::Value;
+
+extern crate time;
+
+fn main() -> ExitCode {
+    let args: Vec<String> = env::args().collect();
+    if args.len() < 2 {
+        eprintln!("Invalid argument count.");
+        return ExitCode::from(0);
+    }
+    let config = match config("/etc/crab.conf") {
+        Some(data) => data,
+        None => return ExitCode::from(1)
+    };
+    let user = match Passwd::current_user() {
+        Some(data) => data,
+        None => {
+            eprintln!("You dont exist.");
+            return ExitCode::from(2);
+        }
+    };
+    let persist = match allowed(&config, &user.name) {
+        Some(data) => data,
+        None => {
+            eprintln!("Operation Not Permitted. This incidence will be reported.");
+            return ExitCode::from(3);
+        }
+    };
+
+    if !validate(&user.name, persist) {
+        eprintln!("Authentication failed.");
+        return ExitCode::from(4);
+    }
+
+    if !unistd::setuid(unistd::geteuid()).is_ok() || !unistd::setgid(unistd::getegid()).is_ok() {
+        eprintln!("Failed to set root permissions");
+        return ExitCode::from(5);
+    };
+
+    let err = exec::execvp(&args[1], &args[1..]);
+    println!("Error: {}", err);
+    
+    ExitCode::from(0)
+}
+
+struct Config {
+    users: Vec<(String, bool)>
+}
+
+fn validate(user: &str, persist: bool) -> bool {
+    if persist && get_persist(user) {
+        return true;
+    }
+    let input = rpassword::prompt_password(format!("crab ({}) password: ", user)).unwrap();
+    let mut auth = pam::Authenticator::with_password("crab").unwrap();
+    auth.get_handler().set_credentials(user.to_owned(), input);
+    if !auth.authenticate().is_ok() || !auth.open_session().is_ok() {
+        return false;
+    }
+    if persist {
+        set_persist(user);
+    }
+    return true;
+}
+
+fn allowed(config: &Config, user: &str) -> Option<bool> {
+    for (name, persist) in &config.users {
+        if name == user {
+            return Some(persist.clone());
+        }
+    }
+    None
+}
+
+fn config(path: &str) -> Option<Config> {
+    let file = match std::fs::read_to_string(path) {
+        Err(e) => {
+            eprintln!("{}: {}", &path, e);
+            return None
+        },
+        Ok(data) => data
+    };
+
+    let mut users = vec![];
+    for (line_num, line) in file.split("\n").enumerate() {
+        let args: Vec<&str> = line.split(" ").collect();
+        if line.trim() == "" {
+            continue;
+        }
+        if args.len() < 2 {
+            eprintln!("Error in config at line {}: Not enough arguments", line_num);
+            continue;
+        }
+        let user: String = args[0].to_string();
+        let persist: bool = match args[1].parse() {
+            Err(e) => {
+                eprintln!("Error in config at line {}: {}", line_num, e);
+                continue;
+            },
+            Ok(data) => data
+        };
+        users.push((user, persist));
+    }
+    Some(Config{users})
+}
+
+fn get_terminal_process() -> Option<i32> {
+    let id: i32 = match std::process::id().try_into() {
+        Ok(data) => data,
+        Err(_) => return None
+    };
+    let stat = match procinfo::pid::stat(id) {
+        Ok(data) => data,
+        Err(_) => return None
+    };
+    Some(stat.tty_nr)
+}
+
+fn get_terminal_config() -> Option<Value> {
+    let id = match get_terminal_process() {
+        Some(data) => data,
+        None => return None
+    };
+    let data = match std::fs::read_to_string(path(&id)) {
+        Ok(data) => data,
+        Err(_) => "{}".to_string()
+    };
+    let json: Value = match serde_json::from_str(&data) {
+        Ok(data) => data,
+        Err(_) => return None
+    };
+    Some(json)
+}
+
+fn write_terminal_config(id: &i32, data: &str) -> Result<(), Box<dyn std::error::Error>> {
+    std::fs::write(path(&id), data)?;
+    unistd::chown(std::path::Path::new(&path(&id)), Some(unistd::Uid::from(0)), Some(unistd::Gid::from(0)))?;
+    let metadata = std::fs::metadata(path(&id))?;
+    let mut perms = metadata.permissions();
+    perms.set_mode(0o0660);
+    fs::set_permissions(path(&id), perms)?;
+    Ok(())
+}
+
+
+fn get_persist(user: &str) -> bool {
+    let json = match get_terminal_config() {
+        Some(data) => data,
+        None => return false
+    };
+    let timestamp = match json[user].as_u64() {
+        Some(data) => data,
+        None => return false
+    };
+    return now() - timestamp < 60 * 3;
+}
+
+fn set_persist(user: &str) {
+    let mut json = match get_terminal_config() {
+        Some(data) => data,
+        None => return
+    };
+    json[user] = Value::from(now());
+    let id = match get_terminal_process() {
+        Some(data) => data,
+        None => return
+    };
+    match write_terminal_config(&id, &json.to_string()) {
+        Ok(_) => {},
+        Err(e) => {
+            eprintln!("Internal Error: {}", e)
+        }
+    };
+}
+
+fn now() -> u64 {
+    return SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap().as_secs();
+}
+
+fn path(id: &i32) -> String {
+    return format!("/tmp/crab-{}", id);
+}
\ No newline at end of file