Rust Secure Coding

 1// ❌ Vulnerable
 2let username = req.param("username");
 3let query = format!("SELECT * FROM users WHERE username = '{}'", username);
 4conn.query(&query);
 5
 6// ✅ Secure (using sqlx)
 7let username = req.param("username");
 8let user = sqlx::query_as!(User, "SELECT * FROM users WHERE username = $1", username)
 9    .fetch_one(&pool)
10    .await?;

 1// ❌ Vulnerable
 2use std::process::Command;
 3let filename = req.param("file");
 4let output = Command::new("sh")
 5    .arg("-c")
 6    .arg(format!("cat {}", filename))
 7    .output()?;
 8
 9// ✅ Secure
10use std::process::Command;
11let filename = req.param("file");
12if !filename.chars().all(|c| c.is_alphanumeric() || c == '.' || c == '_') {
13    return Err(Error::InvalidFilename);
14}
15let output = Command::new("cat")
16    .arg(filename)
17    .output()?;

 1// ❌ Insecure
 2use md5::{Md5, Digest};
 3let hash = Md5::digest(password.as_bytes());
 4
 5// ✅ Secure
 6use argon2::{
 7    password_hash::{PasswordHash, PasswordHasher, PasswordVerifier, SaltString},
 8    Argon2
 9};
10
11let salt = SaltString::generate(&mut OsRng);
12let argon2 = Argon2::default();
13let password_hash = argon2.hash_password(password.as_bytes(), &salt)?
14    .to_string();
15
16// Verify
17let parsed_hash = PasswordHash::new(&password_hash)?;
18argon2.verify_password(password.as_bytes(), &parsed_hash)?;

 1// ❌ Insecure
 2use rand::Rng;
 3let mut rng = rand::thread_rng();
 4let token: u32 = rng.gen();
 5
 6// ✅ Secure
 7use rand::rngs::OsRng;
 8use rand::RngCore;
 9
10let mut token = [0u8; 32];
11OsRng.fill_bytes(&mut token);

 1// ❌ Dangerous
 2unsafe {
 3    let ptr = some_value as *const i32;
 4    *ptr  // Potential UB
 5}
 6
 7// ✅ Better: Minimize unsafe
 8// Only use unsafe when absolutely necessary
 9// Document safety invariants
10/// # Safety
11/// `ptr` must be valid and aligned
12unsafe fn read_value(ptr: *const i32) -> i32 {
13    ptr.read()
14}