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grub2/0001-blscfg-read-fragments-in-order.patch

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From 434b014e20ebb7930599fe30e09441af6b449fef Mon Sep 17 00:00:00 2001
From: Michael Chang <mchang@suse.com>
Date: Mon, 14 Apr 2025 08:52:26 +0800
Subject: [PATCH] blscfg: read fragments in order
The PCR 9 measurements of BLS entry files made by blscfg module are
performed in "readdir" order, which depends on the filesystem and is
therefore inherently unpredictable and unreliable. To make future PCR
values more predictable, the entries should be processed in a
deterministic order, such as alphabetically by filename.
Signed-off-by: Michael Chang <mchang@suse.com>
---
grub-core/commands/blscfg.c | 164 ++++++++++++++++++++++--------------
1 file changed, 103 insertions(+), 61 deletions(-)
diff --git a/grub-core/commands/blscfg.c b/grub-core/commands/blscfg.c
index 343c7ae989..10996722cf 100644
--- a/grub-core/commands/blscfg.c
+++ b/grub-core/commands/blscfg.c
@@ -55,6 +55,15 @@ struct keyval
static struct bls_entry *entries = NULL;
+struct bls_fragment
+{
+ struct bls_fragment *next;
+ struct bls_fragment *prev;
+ char *filename;
+};
+typedef struct bls_fragment *bls_fragment_t;
+static bls_fragment_t fragments;
+
#define FOR_BLS_ENTRIES(var) FOR_LIST_ELEMENTS (var, entries)
/* BLS appears to make paths relative to the filesystem that snippets are
@@ -466,69 +475,41 @@ struct read_entry_info {
grub_file_t file;
};
-static int read_entry (
- const char *filename,
- const struct grub_dirhook_info *dirhook_info UNUSED,
- void *data)
+static int
+read_entry (const char *filename)
{
grub_size_t m = 0, n, clip = 0;
int rc = 0;
char *p = NULL;
grub_file_t f = NULL;
struct bls_entry *entry;
- struct read_entry_info *info = (struct read_entry_info *)data;
-
- grub_dprintf ("blscfg", "filename: \"%s\"\n", filename);
+ char *slash;
- n = grub_strlen (filename);
+ grub_dprintf ("blscfg", "read_entry: \"%s\"\n", filename);
- if (info->file)
- {
- f = info->file;
- }
- else
- {
- if (filename[0] == '.')
- return 0;
+ f = grub_file_open (filename, GRUB_FILE_TYPE_CONFIG);
- if (n <= 5)
- return 0;
-
- if (grub_strcmp (filename + n - 5, ".conf") != 0)
- return 0;
-
- p = grub_xasprintf ("(%s)%s/%s", info->devid, info->dirname, filename);
-
- f = grub_file_open (p, GRUB_FILE_TYPE_CONFIG);
- if (!f)
- goto finish;
- }
+ if (!f)
+ goto finish;
entry = grub_zalloc (sizeof (*entry));
if (!entry)
goto finish;
- if (info->file)
- {
- char *slash;
+ /* Strip .conf */
+ n = grub_strlen (filename);
- if (n > 5 && !grub_strcmp (filename + n - 5, ".conf") == 0)
- clip = 5;
+ if (n > 5 && !grub_strcmp (filename + n - 5, ".conf") == 0)
+ clip = 5;
- slash = grub_strrchr (filename, '/');
- if (!slash)
- slash = grub_strrchr (filename, '\\');
+ slash = grub_strrchr (filename, '/');
+ if (!slash)
+ slash = grub_strrchr (filename, '\\');
- while (*slash == '/' || *slash == '\\')
- slash++;
+ while (*slash == '/' || *slash == '\\')
+ slash++;
- m = slash ? slash - filename : 0;
- }
- else
- {
- m = 0;
- clip = 5;
- }
+ m = slash ? slash - filename : 0;
n -= m;
entry->filename = grub_strndup(filename + m, n - clip);
@@ -573,10 +554,7 @@ static int read_entry (
if (rc < 0)
break;
}
-
- if (info->devid)
- entry->devid = grub_strdup(info->devid);
-
+ entry->devid = grub_file_get_device_name (filename);
if (!rc)
bls_add_entry(entry);
@@ -590,6 +568,73 @@ finish:
return 0;
}
+static int
+collect_fragments (
+ const char *filename,
+ const struct grub_dirhook_info *dirhook_info UNUSED,
+ void *data)
+{
+ grub_size_t n;
+ char *p = NULL;
+ struct read_entry_info *info = (struct read_entry_info *)data;
+ bls_fragment_t fragment, f, last;
+
+ if (filename[0] == '.')
+ return 0;
+
+ n = grub_strlen (filename);
+ if (n <= 5)
+ return 0;
+
+ if (grub_strcmp (filename + n - 5, ".conf") != 0)
+ return 0;
+
+ p = grub_xasprintf ("(%s)%s/%s", info->devid, info->dirname, filename);
+
+ fragment = grub_zalloc (sizeof (*fragment));
+ fragment->filename = grub_strdup (p);
+
+ if (!fragments)
+ {
+ fragments = fragment;
+ return 0;
+ }
+
+ FOR_LIST_ELEMENTS (f, fragments)
+ {
+ int rc;
+ rc = grub_strcmp(fragment->filename, f->filename);
+ if (!rc)
+ {
+ grub_free (fragment);
+ return 0;
+ }
+ if (rc < 0)
+ {
+ fragment->next = f;
+ if (f->prev)
+ f->prev->next = fragment;
+ fragment->prev = f->prev;
+ f->prev = fragment;
+ if (f == fragments)
+ {
+ fragments = fragment;
+ fragment->prev = NULL;
+ }
+ return 0;
+ }
+ last = f;
+ }
+
+ if (last)
+ {
+ last->next = fragment;
+ fragment->prev = last;
+ }
+
+ return 0;
+}
+
static grub_envblk_t saved_env = NULL;
static int UNUSED
@@ -1007,6 +1052,7 @@ static int find_entry (struct find_entry_info *info)
const char *blsdir = info->dirname;
int fallback = 0;
int r = 0;
+ bls_fragment_t fragment;
if (!blsdir) {
blsdir = grub_env_get ("blsdir");
@@ -1024,8 +1070,14 @@ static int find_entry (struct find_entry_info *info)
read_entry_info.devid = info->devid;
read_fallback:
- r = blsdir_fs->fs_dir (blsdir_dev, read_entry_info.dirname, read_entry,
+ r = blsdir_fs->fs_dir (blsdir_dev, read_entry_info.dirname, collect_fragments,
&read_entry_info);
+ FOR_LIST_ELEMENTS (fragment, fragments)
+ {
+ grub_dprintf ("blscfg", "read_entry: %s\n", fragment->filename);
+ read_entry (fragment->filename);
+ }
+
if (r != 0) {
grub_dprintf ("blscfg", "read_entry returned error\n");
grub_err_t e;
@@ -1060,21 +1112,11 @@ bls_load_entries (const char *path)
.fs = NULL,
.dirname = NULL,
};
- struct read_entry_info rei = {
- .devid = NULL,
- .dirname = NULL,
- };
if (path) {
len = grub_strlen (path);
if (grub_strcmp (path + len - 5, ".conf") == 0) {
- rei.file = grub_file_open (path, GRUB_FILE_TYPE_CONFIG);
- if (!rei.file)
- return grub_errno;
- /*
- * read_entry() closes the file
- */
- return read_entry(path, NULL, &rei);
+ return read_entry (path);
} else if (path[0] == '(') {
devid = path + 1;
--
2.49.0
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