From 94f6127711fe26606aa46a2207859b3fbfca3cb8 Mon Sep 17 00:00:00 2001
From: Thomas Lamprecht <t.lamprecht@proxmox.com>
Date: Mon, 26 Jul 2021 16:38:16 +0200
Subject: [PATCH] Revert "auth: 'crypt' is not thread safe"

With this I'm getting coredumps on every log in:

> Process 20957 (proxmox-backup-) of user 34 dumped core.
>
> Stack trace of thread 20987:
> #0  0x0000563dec9ac37f _ZN3std3sys4unix14stack_overflow3imp14signal_handler17ha95ed06a038ca319E.llvm.11547235952357801165 (proxmox-backup-proxy)
> #1  0x00007f2638de9840 __restore_rt (libc.so.6)
> #2  0x00007f2638e51dac __stpncpy_sse2_unaligned (libc.so.6)
> #3  0x00007f26393b1340 __sha256_crypt_r (libcrypt.so.1)
> #4  0x00007f26393b0553 __crypt_r (libcrypt.so.1)
> #5  0x0000563dec6e44df _ZN14proxmox_backup4auth5crypt17hd5165f960093dfe7E (proxmox-backup-proxy)

This reverts commit acefa2bb6e91371039ff6040f3cf538b478a24d3.
---
 src/auth.rs | 57 ++++++++++++++---------------------------------------
 1 file changed, 15 insertions(+), 42 deletions(-)

diff --git a/src/auth.rs b/src/auth.rs
index db33b2e4..3272dd6d 100644
--- a/src/auth.rs
+++ b/src/auth.rs
@@ -4,7 +4,7 @@
 
 use std::process::{Command, Stdio};
 use std::io::Write;
-use std::ffi::CStr;
+use std::ffi::{CString, CStr};
 
 use anyhow::{bail, format_err, Error};
 use serde_json::json;
@@ -70,51 +70,24 @@ impl ProxmoxAuthenticator for PAM {
 
 pub struct PBS();
 
-// from libcrypt1, 'lib/crypt.h.in'
-const CRYPT_OUTPUT_SIZE: usize = 384;
-const CRYPT_MAX_PASSPHRASE_SIZE: usize = 512;
-const CRYPT_DATA_RESERVED_SIZE: usize = 767;
-const CRYPT_DATA_INTERNAL_SIZE: usize = 30720;
+pub fn crypt(password: &[u8], salt: &str) -> Result<String, Error> {
 
-#[repr(C)]
-struct crypt_data {
-    output: [libc::c_char; CRYPT_OUTPUT_SIZE],
-    setting: [libc::c_char; CRYPT_OUTPUT_SIZE],
-    input: [libc::c_char; CRYPT_MAX_PASSPHRASE_SIZE],
-    reserved: [libc::c_char; CRYPT_DATA_RESERVED_SIZE],
-    initialized: libc::c_char,
-    internal: [libc::c_char; CRYPT_DATA_INTERNAL_SIZE],
-}
-
-pub fn crypt(password: &[u8], salt: &[u8]) -> Result<String, Error> {
-    #[link(name = "crypt")]
+    #[link(name="crypt")]
     extern "C" {
-        #[link_name = "crypt_r"]
-        fn __crypt_r(
-            key: *const libc::c_char,
-            salt: *const libc::c_char,
-            data: *mut crypt_data,
-        ) -> *mut libc::c_char;
+        #[link_name = "crypt"]
+        fn __crypt(key: *const libc::c_char, salt:  *const libc::c_char) -> * mut libc::c_char;
     }
 
-    let mut data: crypt_data = unsafe { std::mem::zeroed() };
-    for (i, c) in salt.iter().take(data.setting.len() - 1).enumerate() {
-        data.setting[i] = *c as libc::c_char;
-    }
-    for (i, c) in password.iter().take(data.input.len() - 1).enumerate() {
-        data.input[i] = *c as libc::c_char;
-    }
+    let salt = CString::new(salt)?;
+    let password = CString::new(password)?;
 
     let res = unsafe {
-        let status = __crypt_r(
-            &data.input as *const _,
-            &data.setting as *const _,
-            &mut data as *mut _,
-        );
-        if status.is_null() {
-            bail!("internal error: crypt_r returned null pointer");
-        }
-        CStr::from_ptr(&data.output as *const _)
+        CStr::from_ptr(
+            __crypt(
+                password.as_c_str().as_ptr(),
+                salt.as_c_str().as_ptr()
+            )
+        )
     };
     Ok(String::from(res.to_str()?))
 }
@@ -125,11 +98,11 @@ pub fn encrypt_pw(password: &str) -> Result<String, Error> {
     let salt = proxmox::sys::linux::random_data(8)?;
     let salt = format!("$5${}$", base64::encode_config(&salt, base64::CRYPT));
 
-    crypt(password.as_bytes(), salt.as_bytes())
+    crypt(password.as_bytes(), &salt)
 }
 
 pub fn verify_crypt_pw(password: &str, enc_password: &str) -> Result<(), Error> {
-    let verify = crypt(password.as_bytes(), enc_password.as_bytes())?;
+    let verify = crypt(password.as_bytes(), enc_password)?;
     if verify != enc_password {
         bail!("invalid credentials");
     }