feat: add new slice su-support in util-linux

This commit adds a new slice su-support, which segregates the su and
runuser binaries to that slice for granularity. It also modifies the
tests a bit.

slices/util-linux.yaml

@@ -19,6 +19,7 @@ slices:
       - libudev1_libs
       - libuuid1_libs
       - util-linux_generated
+      - util-linux_su-support
       - zlib1g_libs
     contents:
       /usr/bin/addpart:
@@ -67,7 +68,6 @@ slices:
       /usr/bin/setpriv:
       /usr/bin/setsid:
       /usr/bin/setterm:
-      /usr/bin/su:
       /usr/bin/taskset:
       /usr/bin/uclampset:
       /usr/bin/unshare:
@@ -100,28 +100,46 @@ slices:
       /usr/sbin/pivot_root:
       /usr/sbin/readprofile:
       /usr/sbin/rtcwake:
-      /usr/sbin/runuser:
       /usr/sbin/sulogin:
       /usr/sbin/swaplabel:
       /usr/sbin/switch_root:
       /usr/sbin/wipefs:
       /usr/sbin/zramctl:
 
+  # Contains the binaries which supports running commands with substitute user
+  # and group IDs.
+  su-support:
+    essential:
+      - libaudit1_libs
+      - libc6_libs
+      - libcap-ng0_libs
+      - libpam0g_libs
+      - util-linux_pam-profiles
+    contents:
+      /usr/bin/su:
+      /usr/sbin/runuser:
+
+
   # the following emulates the post-install script
   generated:
+    essential:
+      # Since the more binary is located at ./usr/bin/more and /bin in noble
+      # points to /usr/bin via base-files, the base-files_bin slice is included
+      # here.
+      - base-files_bin
     contents:
-      /usr/bin/pager: {symlink: /usr/bin/more}
+      /usr/bin/pager: {symlink: /bin/more}
 
   mime:
     contents:
       /usr/lib/mime/packages/util-linux:
 
-  pam-profile:
+  pam-profiles:
     contents:
-    /etc/pam.d/runuser:
-    /etc/pam.d/runuser-l:
-    /etc/pam.d/su:
-    /etc/pam.d/su-l:
+      /etc/pam.d/runuser:
+      /etc/pam.d/runuser-l:
+      /etc/pam.d/su:
+      /etc/pam.d/su-l:
 
   services:
     essential:

tests/spread/integration/util-linux/task.yaml

@@ -20,6 +20,13 @@ execute: |
   chroot "${rootfs}" lsmem | grep "Total online memory"
   chroot "${rootfs}" whereis lsblk | grep "/usr/bin/lsblk"
 
+  # Test the su and runuser binaries
+  cp /etc/passwd "${rootfs}"/etc/passwd
+  echo "foo:x:1001:1001:Test user,,,:/tmp:/bin/bash" >>"${rootfs}"/etc/passwd
+  cp /usr/bin/whoami "${rootfs}"/usr/bin/
+  chroot "${rootfs}" su foo -c whoami | grep "foo"
+  chroot "${rootfs}" runuser foo -c whoami | grep "foo"
+
   # cleanup
   umount -l "${rootfs}"/dev
   umount -l "${rootfs}"/sys