From 76e8acce12fe6e914fdab422c8af44956c1dac04 Mon Sep 17 00:00:00 2001
From: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Date: Wed, 17 Mar 2021 21:54:58 +0200
Subject: [PATCH] efi_loader: Add device path related functions for initrd via
Boot####
On the following patches we allow for an initrd path to be stored in
Boot#### variables. Specifically we encode in the FIlePathList[] of
the EFI_LOAD_OPTIONS for each Boot#### variable.
The FilePathList[] array looks like this:
kernel - 0xff - VenMedia(initrd GUID) - initrd1 - 0x01 initrd2 - 0xff
So let's add the relevant functions to concatenate and retrieve a device
path based on a Vendor GUID.
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reformat function descriptions.
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
---
include/efi_loader.h | 4 ++
lib/efi_loader/efi_device_path.c | 110 +++++++++++++++++++++++++++++--
2 files changed, 109 insertions(+), 5 deletions(-)
diff --git a/include/efi_loader.h b/include/efi_loader.h
index 68daa1a4a9..5d534e69bb 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -744,6 +744,10 @@ struct efi_load_option {
const u8 *optional_data;
};
+struct efi_device_path *efi_dp_from_lo(struct efi_load_option *lo,
+ efi_uintn_t *size, efi_guid_t guid);
+struct efi_device_path *efi_dp_concat(const struct efi_device_path *dp1,
+ const struct efi_device_path *dp2);
efi_status_t efi_deserialize_load_option(struct efi_load_option *lo, u8 *data,
efi_uintn_t *size);
unsigned long efi_serialize_load_option(struct efi_load_option *lo, u8 **data);
diff --git a/lib/efi_loader/efi_device_path.c b/lib/efi_loader/efi_device_path.c
index 398dbc699b..4b20859b25 100644
--- a/lib/efi_loader/efi_device_path.c
+++ b/lib/efi_loader/efi_device_path.c
@@ -282,11 +282,31 @@ struct efi_device_path *efi_dp_dup(const struct efi_device_path *dp)
return ndp;
}
-struct efi_device_path *efi_dp_append(const struct efi_device_path *dp1,
- const struct efi_device_path *dp2)
+/**
+ * efi_dp_append_or_concatenate() - Append or concatenate two device paths.
+ * Concatenated device path will be separated
+ * by a sub-type 0xff end node
+ *
+ * @dp1: First device path
+ * @dp2: Second device path
+ * @concat: If true the two device paths will be concatenated and separated
+ * by an end of entrire device path sub-type 0xff end node.
+ * If true the second device path will be appended to the first and
+ * terminated by an end node
+ *
+ * Return:
+ * concatenated device path or NULL. Caller must free the returned value
+ */
+static struct
+efi_device_path *efi_dp_append_or_concatenate(const struct efi_device_path *dp1,
+ const struct efi_device_path *dp2,
+ bool concat)
{
struct efi_device_path *ret;
+ size_t end_size = sizeof(END);
+ if (concat)
+ end_size = 2 * sizeof(END);
if (!dp1 && !dp2) {
/* return an end node */
ret = efi_dp_dup(&END);
@@ -298,18 +318,58 @@ struct efi_device_path *efi_dp_append(const struct efi_device_path *dp1,
/* both dp1 and dp2 are non-null */
unsigned sz1 = efi_dp_size(dp1);
unsigned sz2 = efi_dp_size(dp2);
- void *p = dp_alloc(sz1 + sz2 + sizeof(END));
+ void *p = dp_alloc(sz1 + sz2 + end_size);
if (!p)
return NULL;
+ ret = p;
memcpy(p, dp1, sz1);
+ p += sz1;
+
+ if (concat) {
+ memcpy(p, &END, sizeof(END));
+ p += sizeof(END);
+ }
+
/* the end node of the second device path has to be retained */
- memcpy(p + sz1, dp2, sz2 + sizeof(END));
- ret = p;
+ memcpy(p, dp2, sz2);
+ p += sz2;
+ memcpy(p, &END, sizeof(END));
}
return ret;
}
+/**
+ * efi_dp_append() - Append a device to an existing device path.
+ *
+ * @dp1: First device path
+ * @dp2: Second device path
+ *
+ * Return:
+ * concatenated device path or NULL. Caller must free the returned value
+ */
+struct efi_device_path *efi_dp_append(const struct efi_device_path *dp1,
+ const struct efi_device_path *dp2)
+{
+ return efi_dp_append_or_concatenate(dp1, dp2, false);
+}
+
+/**
+ * efi_dp_concat() - Concatenate 2 device paths. The final device path will
+ * contain two device paths separated by and end node (0xff).
+ *
+ * @dp1: First device path
+ * @dp2: Second device path
+ *
+ * Return:
+ * concatenated device path or NULL. Caller must free the returned value
+ */
+struct efi_device_path *efi_dp_concat(const struct efi_device_path *dp1,
+ const struct efi_device_path *dp2)
+{
+ return efi_dp_append_or_concatenate(dp1, dp2, true);
+}
+
struct efi_device_path *efi_dp_append_node(const struct efi_device_path *dp,
const struct efi_device_path *node)
{
@@ -1183,3 +1243,43 @@ ssize_t efi_dp_check_length(const struct efi_device_path *dp,
dp = (const struct efi_device_path *)((const u8 *)dp + len);
}
}
+
+/**
+ * efi_dp_from_lo() - Get the instance of a VenMedia node in a
+ * multi-instance device path that matches
+ * a specific GUID. This kind of device paths
+ * is found in Boot#### options describing an
+ * initrd location
+ *
+ * @lo: EFI_LOAD_OPTION containing a valid device path
+ * @size: size of the discovered device path
+ * @guid: guid to search for
+ *
+ * Return:
+ * device path including the VenMedia node or NULL.
+ * Caller must free the returned value.
+ */
+struct
+efi_device_path *efi_dp_from_lo(struct efi_load_option *lo,
+ efi_uintn_t *size, efi_guid_t guid)
+{
+ struct efi_device_path *fp = lo->file_path;
+ struct efi_device_path_vendor *vendor;
+ int lo_len = lo->file_path_length;
+
+ for (; lo_len >= sizeof(struct efi_device_path);
+ lo_len -= fp->length, fp = (void *)fp + fp->length) {
+ if (lo_len < 0 || efi_dp_check_length(fp, lo_len) < 0)
+ break;
+ if (fp->type != DEVICE_PATH_TYPE_MEDIA_DEVICE ||
+ fp->sub_type != DEVICE_PATH_SUB_TYPE_VENDOR_PATH)
+ continue;
+
+ vendor = (struct efi_device_path_vendor *)fp;
+ if (!guidcmp(&vendor->guid, &guid))
+ return efi_dp_dup(fp);
+ }
+ log_debug("VenMedia(%pUl) not found in %ls\n", &guid, lo->label);
+
+ return NULL;
+}
--
2.39.5