From 36a2be13c4a744751adf63ae881506bf15a5ff00 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Mon, 18 Nov 2024 11:23:26 +0100
Subject: [PATCH] random-util: include pidfdid in fallback RNG buffer

This doesn't make the RNG cryptographic strength, but if we have it
easily accessible, why not include the pidfd id. It is after all not
vulnerable to reuse.
---
 src/basic/random-util.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/basic/random-util.c b/src/basic/random-util.c
index 866f0ba5ed7..fec4f810358 100644
--- a/src/basic/random-util.c
+++ b/src/basic/random-util.c
@@ -23,6 +23,7 @@
 #include "missing_syscall.h"
 #include "missing_threads.h"
 #include "parse-util.h"
+#include "pidfd-util.h"
 #include "process-util.h"
 #include "random-util.h"
 #include "sha256.h"
@@ -39,6 +40,7 @@ static void fallback_random_bytes(void *p, size_t n) {
                 uint64_t call_id, block_id;
                 usec_t stamp_mono, stamp_real;
                 pid_t pid, tid;
+                uint64_t pidfdid;
                 uint8_t auxval[16];
         } state = {
                 /* Arbitrary domain separation to prevent other usage of AT_RANDOM from clashing. */
@@ -51,6 +53,7 @@ static void fallback_random_bytes(void *p, size_t n) {
 
         memcpy(state.label, "systemd fallback random bytes v1", sizeof(state.label));
         memcpy(state.auxval, ULONG_TO_PTR(getauxval(AT_RANDOM)), sizeof(state.auxval));
+        (void) pidfd_get_inode_id_self_cached(&state.pidfdid);
 
         while (n > 0) {
                 struct sha256_ctx ctx;