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isohybrid: Make GPT GUIDs reproducible with --uefi and --id

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Resolves: #RHEL-96214
Signed-off-by: Leo Sandoval <lsandova@redhat.com>
This commit is contained in:
Leo Sandoval 2025-06-13 13:16:48 -06:00
parent 6d54aa6cf2
commit 756a438b5b
3 changed files with 84 additions and 1 deletions
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78
0008-isohybrid-Make-GPT-GUIDs-reproducible-with-uefi-and-.patch Normal file
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@ -0,0 +1,78 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Chris Riches <chris.riches@nutanix.com>
Date: Fri, 13 Jun 2025 13:10:03 -0600
Subject: [PATCH] isohybrid: Make GPT GUIDs reproducible with --uefi and --id
We already have the --id option to make the MBR ID reproducible,
however the GPT GUIDs are always random, making it impossible to
hybridise reproducibly with the --uefi option.
Switch from v4 to v5 UUIDs when --id is set, computing them from the MBR
ID via arbitrary fixed namespaces + SHA1 hashing.
Signed-off-by: Chris Riches <chris.riches at nutanix.com>
Signed-off-by: Leo Sandoval <lsandova@redhat.com>
---
utils/isohybrid.c | 28 +++++++++++++++++++++++++---
1 file changed, 25 insertions(+), 3 deletions(-)
diff --git a/utils/isohybrid.c b/utils/isohybrid.c
index 1a203213..681157cd 100644
--- a/utils/isohybrid.c
+++ b/utils/isohybrid.c
@@ -48,6 +48,18 @@ unsigned int padding = 0;
uuid_t disk_uuid, part_uuid, iso_uuid;
+UUID_DEFINE(disk_uuid_ns,
+ 0x13, 0x40, 0x46, 0xef, 0x45, 0x39, 0x4c, 0xd6,
+ 0x83, 0x23, 0x27, 0xa9, 0x23, 0x77, 0x78, 0x68);
+
+UUID_DEFINE(part_uuid_ns,
+ 0x24, 0x08, 0x39, 0x02, 0x5d, 0x03, 0x42, 0x49,
+ 0x83, 0xb1, 0x99, 0x76, 0xfb, 0xe7, 0x38, 0x5c);
+
+UUID_DEFINE(iso_uuid_ns,
+ 0x50, 0x3a, 0xbc, 0xed, 0xc7, 0xa4, 0x40, 0x1c,
+ 0xa1, 0xe3, 0x2c, 0xf6, 0x85, 0x3f, 0xeb, 0x81);
+
uint8_t mode = 0;
enum { VERBOSE = 1 , EFI = 2 , MAC = 4};
@@ -775,6 +787,16 @@ uint32_t chksum_crc32 (unsigned char *block, unsigned int length)
return (crc ^ 0xFFFFFFFF);
}
+void
+gen_uuid(uuid_t out, const uuid_t ns)
+{
+ if (id) {
+ uuid_generate_sha1(out, ns, (char*)&id, sizeof(id));
+ } else {
+ uuid_generate(out);
+ }
+}
+
void
reverse_uuid(uuid_t uuid)
{
@@ -815,7 +837,7 @@ initialise_gpt(uint8_t *gpt, uint32_t current, uint32_t alternate, int primary)
}
if (primary) {
- uuid_generate(disk_uuid);
+ gen_uuid(disk_uuid, disk_uuid_ns);
reverse_uuid(disk_uuid);
}
@@ -842,8 +864,8 @@ initialise_gpt(uint8_t *gpt, uint32_t current, uint32_t alternate, int primary)
part = (struct gpt_part_header *)gpt;
if (primary) {
- uuid_generate(part_uuid);
- uuid_generate(iso_uuid);
+ gen_uuid(part_uuid, part_uuid_ns);
+ gen_uuid(iso_uuid, iso_uuid_ns);
reverse_uuid(part_uuid);
reverse_uuid(iso_uuid);
}

1
syslinux.patches
View File

@ -5,3 +5,4 @@ Patch0004: 0004-Add-RPMOPTFLAGS-to-CFLAGS-for-some-stuff.patch
Patch0005: 0005-Workaround-multiple-definition-of-symbol-errors.patch
Patch0006: 0006-Replace-builtin-strlen-that-appears-to-get-optimized.patch
Patch0007: 0007-Fix-backspace-when-editing-a-multiline-cmdline.patch
Patch0008: 0008-isohybrid-Make-GPT-GUIDs-reproducible-with-uefi-and-.patch

6
syslinux.spec
View File

@ -7,7 +7,7 @@ Summary: Simple kernel loader which boots from a FAT filesystem
Name: syslinux
Version: 6.04
%define tarball_version 6.04-pre1
Release: 0.21%{?dist}
Release: 0.22%{?dist}
License: GPLv2+
URL: http://syslinux.zytor.com/wiki/index.php/The_Syslinux_Project
Source0: http://www.kernel.org/pub/linux/utils/boot/syslinux/%{name}-%{tarball_version}.tar.xz
@ -253,6 +253,10 @@ fi
%endif
%changelog
* Fri Jun 13 2025 Leo Sandoval <lsandova@redhat.com> - 6.04-0.22
- isohybrid: Make GPT GUIDs reproducible with --uefi and --id
- Resolves: #RHEL-96214
* Mon Jun 16 2025 Leo Sandoval <lsandova@redhat.com> - 6.04-0.21
- Build tftpboot on x86_64 instead of i686
- Resolves: #RHEL-97105