From e3dfedee10cb0c348d748bf438c76e5c3623ad69 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Mon, 21 Nov 2022 15:32:22 +0100
Subject: [PATCH] udev: make sure auto-root logic also works in UKIs booted
 from XBOOTLDR
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If no root= switch is specified on the kernel command line we'll use the
root disk on which the partition the LoaderDevicePartUUID efi var is
located – as long as that partition is an ESP. Let's slightly liberalize
that and also allow it if that partition is an XBOOTLDR partition. This
ensures that UKIs spawned directly from XBOOTLDR work the same as those
from the ESP.

(Note that this makes no difference if sd-boot is in the mix, as in that
case LoaderDevicePartUUID is always set to the ESP, as that's where
sd-boot is located, and sd-boot will set the var first, sd-stub will
only set it later if it#s not set yet.)

(cherry picked from commit e4cb147a2e230a4a0b804c3e70f2692a5e2fd698)

Related: #2138081
---
 src/udev/udev-builtin-blkid.c | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/src/udev/udev-builtin-blkid.c b/src/udev/udev-builtin-blkid.c
index 92ea43eef0..9f5646ffdd 100644
--- a/src/udev/udev-builtin-blkid.c
+++ b/src/udev/udev-builtin-blkid.c
@@ -120,14 +120,14 @@ static int find_gpt_root(sd_device *dev, blkid_probe pr, bool test) {
 #if defined(SD_GPT_ROOT_NATIVE) && ENABLE_EFI
 
         _cleanup_free_ char *root_id = NULL, *root_label = NULL;
-        bool found_esp = false;
+        bool found_esp_or_xbootldr = false;
         int r;
 
         assert(pr);
 
-        /* Iterate through the partitions on this disk, and see if the
-         * EFI ESP we booted from is on it. If so, find the first root
-         * disk, and add a property indicating its partition UUID. */
+        /* Iterate through the partitions on this disk, and see if the UEFI ESP or XBOOTLDR partition we
+         * booted from is on it. If so, find the first root disk, and add a property indicating its partition
+         * UUID. */
 
         errno = 0;
         blkid_partlist pl = blkid_probe_get_partitions(pr);
@@ -157,21 +157,20 @@ static int find_gpt_root(sd_device *dev, blkid_probe pr, bool test) {
                 if (sd_id128_from_string(stype, &type) < 0)
                         continue;
 
-                if (sd_id128_equal(type, SD_GPT_ESP)) {
-                        sd_id128_t id, esp;
+                if (sd_id128_in_set(type, SD_GPT_ESP, SD_GPT_XBOOTLDR)) {
+                        sd_id128_t id, esp_or_xbootldr;
 
-                        /* We found an ESP, let's see if it matches
-                         * the ESP we booted from. */
+                        /* We found an ESP or XBOOTLDR, let's see if it matches the ESP/XBOOTLDR we booted from. */
 
                         if (sd_id128_from_string(sid, &id) < 0)
                                 continue;
 
-                        r = efi_loader_get_device_part_uuid(&esp);
+                        r = efi_loader_get_device_part_uuid(&esp_or_xbootldr);
                         if (r < 0)
                                 return r;
 
-                        if (sd_id128_equal(id, esp))
-                                found_esp = true;
+                        if (sd_id128_equal(id, esp_or_xbootldr))
+                                found_esp_or_xbootldr = true;
 
                 } else if (sd_id128_equal(type, SD_GPT_ROOT_NATIVE)) {
                         unsigned long long flags;
@@ -195,9 +194,9 @@ static int find_gpt_root(sd_device *dev, blkid_probe pr, bool test) {
                 }
         }
 
-        /* We found the ESP on this disk, and also found a root
-         * partition, nice! Let's export its UUID */
-        if (found_esp && root_id)
+        /* We found the ESP/XBOOTLDR on this disk, and also found a root partition, nice! Let's export its
+         * UUID */
+        if (found_esp_or_xbootldr && root_id)
                 udev_builtin_add_property(dev, test, "ID_PART_GPT_AUTO_ROOT_UUID", root_id);
 #endif