From f92095fe81cabc14bf1a31ec94eff50414ca3a22 Mon Sep 17 00:00:00 2001
From: Andy Fiddaman <illumos@fiddaman.net>
Date: Wed, 15 Nov 2023 19:39:06 +0000
Subject: [PATCH] Improve wtmp record mangling.

This fixes two problems with the current wtmp/utmp record mangling.
First it is not idempotent, the system's notion of boot time is
set to the current time of day whenever sled agent confirms that
time is synchronised. Secondly, this is only approximate even for the
first sled agent start, but it's plain wrong if sled agent restarts
later.

In conjunction with changes to stlouis, the `tmpx` utility is now
able to process all zones itself, and uses the true system boot
time for each zone when updating records.

Fixes: https://github.com/oxidecomputer/omicron/issues/3514
---
 sled-agent/src/services.rs | 45 +++++++++-----------------------------
 1 file changed, 10 insertions(+), 35 deletions(-)

diff --git a/sled-agent/src/services.rs b/sled-agent/src/services.rs
index b87c91768ba..11c357a845c 100644
--- a/sled-agent/src/services.rs
+++ b/sled-agent/src/services.rs
@@ -100,13 +100,11 @@ use sled_storage::manager::StorageHandle;
 use slog::Logger;
 use std::collections::BTreeMap;
 use std::collections::HashSet;
-use std::iter;
 use std::iter::FromIterator;
 use std::net::{IpAddr, Ipv6Addr, SocketAddr};
 use std::str::FromStr;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
-use std::time::{SystemTime, UNIX_EPOCH};
 use tokio::io::AsyncWriteExt;
 use tokio::sync::oneshot;
 use tokio::sync::Mutex;
@@ -2384,10 +2382,7 @@ impl ServiceManager {
         Ok(())
     }
 
-    pub fn boottime_rewrite<'a>(
-        &self,
-        zones: impl Iterator<Item = &'a RunningZone>,
-    ) {
+    pub fn boottime_rewrite(&self) {
         if self
             .inner
             .time_synced
@@ -2398,33 +2393,13 @@ impl ServiceManager {
             return;
         }
 
-        let now = SystemTime::now()
-            .duration_since(UNIX_EPOCH)
-            .expect("SystemTime before UNIX EPOCH");
-
-        info!(self.inner.log, "Setting boot time to {:?}", now);
-
-        let files: Vec<Utf8PathBuf> = zones
-            .map(|z| z.root())
-            .chain(iter::once(Utf8PathBuf::from("/")))
-            .flat_map(|r| [r.join("var/adm/utmpx"), r.join("var/adm/wtmpx")])
-            .collect();
-
-        for file in files {
-            let mut command = std::process::Command::new(PFEXEC);
-            let cmd = command.args(&[
-                "/usr/platform/oxide/bin/tmpx",
-                &format!("{}", now.as_secs()),
-                &file.as_str(),
-            ]);
-            match execute(cmd) {
-                Err(e) => {
-                    warn!(self.inner.log, "Updating {} failed: {}", &file, e);
-                }
-                Ok(_) => {
-                    info!(self.inner.log, "Updated {}", &file);
-                }
-            }
+        // Call out to the 'tmpx' utility program which will rewrite the wtmpx
+        // and utmpx databases in every zone, including the global zone, to
+        // reflect the adjusted system boot time.
+        let mut command = std::process::Command::new(PFEXEC);
+        let cmd = command.args(&["/usr/platform/oxide/bin/tmpx", "-Z"]);
+        if let Err(e) = execute(cmd) {
+            warn!(self.inner.log, "Updating [wu]tmpx databases failed: {}", e);
         }
     }
 
@@ -2433,7 +2408,7 @@ impl ServiceManager {
 
         if let Some(true) = self.inner.skip_timesync {
             info!(self.inner.log, "Configured to skip timesync checks");
-            self.boottime_rewrite(existing_zones.values());
+            self.boottime_rewrite();
             return Ok(TimeSync {
                 sync: true,
                 ref_id: 0,
@@ -2487,7 +2462,7 @@ impl ServiceManager {
                         && correction.abs() <= 0.05;
 
                     if sync {
-                        self.boottime_rewrite(existing_zones.values());
+                        self.boottime_rewrite();
                     }
 
                     Ok(TimeSync {