Merge lp:~jamesodhunt/ubuntu/vivid/upstart/bug-1425685-additional into lp:ubuntu/vivid/upstart

[James Hunt]

* debian/upstart-bin.upstart.cron.daily: Ensure the session uid matches that
  of the session file itself to stop a user forcing the logrotation of
  another users logs.

[Colin Watson (cjwatson)]

review: Approve

=== modified file 'debian/changelog'
--- debian/changelog	2015-02-26 12:34:53 +0000
+++ debian/changelog	2015-02-26 14:03:28 +0000
@@ -1,3 +1,11 @@
+upstart (1.13.2-0ubuntu9) UNRELEASED; urgency=medium
+
+  * debian/upstart-bin.upstart.cron.daily: Ensure the session uid matches that
+    of the session file itself to stop a user forcing the logrotation of
+    another users logs.
+
+ -- James Hunt <[e-mail]>  Thu, 26 Feb 2015 13:58:32 +0000
+
 upstart (1.13.2-0ubuntu8) vivid; urgency=medium
 
   * debian/upstart-bin.upstart.cron.daily:

=== modified file 'debian/upstart-bin.upstart.cron.daily'
--- debian/upstart-bin.upstart.cron.daily	2015-02-26 12:22:49 +0000
+++ debian/upstart-bin.upstart.cron.daily	2015-02-26 14:03:28 +0000
@@ -16,10 +16,19 @@
     [ -f "$file" ] || continue
     [ -h "$file" ] && continue
 
+    file_uid=$(stat -c %u "$file")
+    [ -n "$file_uid" ] || continue
+
     session=$(grep \
 	    "^UPSTART_SESSION=unix:abstract=/com/ubuntu/upstart-session/[0-9][0-9]*/[0-9][0-9]*$" \
 	    "$file" 2>/dev/null || true)
-    [ -z "$session" ] && continue
+    [ -n "$session" ] || continue
+
+    session_uid=$(echo "$session" | cut -d\/ -f5)
+    [ -n "$session_uid" ] || continue
+
+    # Don't allow a user to spoof logrotation for another user.
+    [ "$file_uid" = "$session_uid" ] || continue
 
     env -i "$session" /sbin/initctl emit rotate-logs >/dev/null 2>&1 || true
 done