sd-boot: also look for boot loader entries in the XBOOTLDR partition
authorLennart Poettering <lennart@poettering.net>
Fri, 8 Feb 2019 12:04:41 +0000 (13:04 +0100)
committerLennart Poettering <lennart@poettering.net>
Fri, 1 Mar 2019 11:41:32 +0000 (12:41 +0100)
The specification always said so, let's actually implement this.

Unfortunately UEFI's own APIs don't allow us to search for partition
type GUID, hence we have to implement a minimal GPT parser ourselves.

src/boot/efi/boot.c
src/boot/efi/crc32.c [new file with mode: 0644]
src/boot/efi/crc32.h [new file with mode: 0644]
src/boot/efi/meson.build

index 35c649f..188ce65 100644 (file)
@@ -1,9 +1,11 @@
 /* SPDX-License-Identifier: LGPL-2.1+ */
 
 #include <efi.h>
+#include <efigpt.h>
 #include <efilib.h>
 
 #include "console.h"
+#include "crc32.h"
 #include "disk.h"
 #include "graphics.h"
 #include "linux.h"
@@ -1955,6 +1957,193 @@ static VOID config_entry_add_linux(
         uefi_call_wrapper(linux_dir->Close, 1, linux_dir);
 }
 
+/* Note that this is in GUID format, i.e. the first 32bit, and the following pair of 16bit are byteswapped. */
+static const UINT8 xbootldr_guid[16] = {
+        0xff, 0xc2, 0x13, 0xbc, 0xe6, 0x59, 0x62, 0x42, 0xa3, 0x52, 0xb2, 0x75, 0xfd, 0x6f, 0x71, 0x72
+};
+
+EFI_DEVICE_PATH *path_parent(EFI_DEVICE_PATH *path, EFI_DEVICE_PATH *node) {
+        EFI_DEVICE_PATH *parent;
+        UINTN len;
+
+        len = (UINT8*) NextDevicePathNode(node) - (UINT8*) path;
+        parent = (EFI_DEVICE_PATH*) AllocatePool(len + sizeof(EFI_DEVICE_PATH));
+        CopyMem(parent, path, len);
+        CopyMem((UINT8*) parent + len, EndDevicePath, sizeof(EFI_DEVICE_PATH));
+
+        return parent;
+}
+
+static VOID config_load_xbootldr(
+                Config *config,
+                EFI_HANDLE *device) {
+
+        EFI_DEVICE_PATH *partition_path, *node, *disk_path, *copy;
+        UINT32 found_partition_number = (UINT32) -1;
+        UINT64 found_partition_start = (UINT64) -1;
+        UINT64 found_partition_size = (UINT64) -1;
+        UINT8 found_partition_signature[16] = {};
+        EFI_HANDLE new_device;
+        EFI_FILE *root_dir;
+        EFI_STATUS r;
+
+        partition_path = DevicePathFromHandle(device);
+        if (!partition_path)
+                return;
+
+        for (node = partition_path; !IsDevicePathEnd(node); node = NextDevicePathNode(node)) {
+                EFI_HANDLE disk_handle;
+                EFI_BLOCK_IO *block_io;
+                EFI_DEVICE_PATH *p;
+                UINTN nr;
+
+                /* First, Let's look for the SCSI/SATA/USB/… device path node, i.e. one above the media
+                 * devices */
+                if (DevicePathType(node) != MESSAGING_DEVICE_PATH)
+                        continue;
+
+                /* Determine the device path one level up */
+                disk_path = path_parent(partition_path, node);
+                p = disk_path;
+                r = uefi_call_wrapper(BS->LocateDevicePath, 3, &BlockIoProtocol, &p, &disk_handle);
+                if (EFI_ERROR(r))
+                        continue;
+
+                r = uefi_call_wrapper(BS->HandleProtocol, 3, disk_handle, &BlockIoProtocol, (VOID **)&block_io);
+                if (EFI_ERROR(r))
+                        continue;
+
+                /* Filter out some block devices early. (We only care about block devices that aren't
+                 * partitions themselves — we look for GPT partition tables to parse after all —, and only
+                 * those which contain a medium and have at least 2 blocks.) */
+                if (block_io->Media->LogicalPartition ||
+                    !block_io->Media->MediaPresent ||
+                    block_io->Media->LastBlock <= 1)
+                        continue;
+
+                /* Try both copies of the GPT header, in case one is corrupted */
+                for (nr = 0; nr < 2; nr++) {
+                        _cleanup_freepool_ EFI_PARTITION_ENTRY* entries = NULL;
+                        union {
+                                EFI_PARTITION_TABLE_HEADER gpt_header;
+                                uint8_t space[((sizeof(EFI_PARTITION_TABLE_HEADER) + 511) / 512) * 512];
+                        } gpt_header_buffer;
+                        UINT64 where;
+                        UINTN i, sz;
+                        UINT32 c;
+
+                        if (nr == 0)
+                                where = 1; /* Read the first copy at LBA 1 */
+                        else
+                                where = block_io->Media->LastBlock; /* Read the second copy at the very last LBA of this block device */
+
+                        /* Read the GPT header */
+                        r = uefi_call_wrapper(block_io->ReadBlocks, 5, block_io, block_io->Media->MediaId, where, sizeof(gpt_header_buffer), &gpt_header_buffer);
+                        if (EFI_ERROR(r))
+                                continue;
+
+                        /* Some superficial validation of the GPT header */
+                        if (CompareMem(&gpt_header_buffer.gpt_header.Header.Signature, "EFI PART", sizeof(gpt_header_buffer.gpt_header.Header.Signature)) != 0)
+                                continue;
+
+                        if (gpt_header_buffer.gpt_header.Header.HeaderSize < 92 || gpt_header_buffer.gpt_header.Header.HeaderSize > 512)
+                                continue;
+
+                        if (gpt_header_buffer.gpt_header.Header.Revision != 0x00010000U)
+                                continue;
+
+                        /* Calculate CRC check */
+                        c = ~crc32_exclude_offset((UINT32) -1, (const UINT8*) &gpt_header_buffer, gpt_header_buffer.gpt_header.Header.HeaderSize,
+                                                  OFFSETOF(EFI_PARTITION_TABLE_HEADER, Header.CRC32), sizeof(gpt_header_buffer.gpt_header.Header.CRC32));
+                        if (c != gpt_header_buffer.gpt_header.Header.CRC32)
+                                continue;
+
+                        if (gpt_header_buffer.gpt_header.MyLBA != where)
+                                continue;
+
+                        if (gpt_header_buffer.gpt_header.SizeOfPartitionEntry < sizeof(EFI_PARTITION_ENTRY))
+                                continue;
+
+                        if (gpt_header_buffer.gpt_header.NumberOfPartitionEntries <= 0 || gpt_header_buffer.gpt_header.NumberOfPartitionEntries > 1024)
+                                continue;
+
+                        /* Now load the GPT entry table */
+                        sz = ((gpt_header_buffer.gpt_header.SizeOfPartitionEntry * gpt_header_buffer.gpt_header.NumberOfPartitionEntries + 511) / 512) * 512;
+                        entries = AllocatePool(sz);
+
+                        r = uefi_call_wrapper(block_io->ReadBlocks, 5, block_io, block_io->Media->MediaId, gpt_header_buffer.gpt_header.PartitionEntryLBA, sz, entries);
+                        if (EFI_ERROR(r))
+                                continue;
+
+                        /* Calculate CRC of entries array, too */
+                        c = ~crc32((UINT32) -1, entries, sz);
+                        if (c != gpt_header_buffer.gpt_header.PartitionEntryArrayCRC32)
+                                continue;
+
+                        for (i = 0; i < gpt_header_buffer.gpt_header.NumberOfPartitionEntries; i++) {
+                                EFI_PARTITION_ENTRY *entry;
+
+                                entry = (EFI_PARTITION_ENTRY*) ((UINT8*) entries + gpt_header_buffer.gpt_header.SizeOfPartitionEntry * i);
+
+                                if (CompareMem(&entry->PartitionTypeGUID, xbootldr_guid, 16) == 0) {
+                                        UINT64 end;
+
+                                        /* Let's use memcpy(), in case the structs are not aligned (they really should be though) */
+                                        CopyMem(&found_partition_start, &entry->StartingLBA, sizeof(found_partition_start));
+                                        CopyMem(&end, &entry->EndingLBA, sizeof(end));
+
+                                        if (end < found_partition_start) /* Bogus? */
+                                                continue;
+
+                                        found_partition_size = end - found_partition_start + 1;
+                                        CopyMem(found_partition_signature, &entry->UniquePartitionGUID, sizeof(found_partition_signature));
+
+                                        found_partition_number = i + 1;
+                                        goto found;
+                                }
+                        }
+
+                        break; /* This GPT was fully valid, but we didn't find what we are looking for. This
+                                * means there's no reason to check the second copy of the GPT header */
+                }
+        }
+
+        return; /* Not found */
+
+found:
+        copy = DuplicateDevicePath(partition_path);
+
+        /* Patch in the data we found */
+        for (node = copy; !IsDevicePathEnd(node); node = NextDevicePathNode(node)) {
+                HARDDRIVE_DEVICE_PATH *hd;
+
+                if (DevicePathType(node) != MEDIA_DEVICE_PATH)
+                        continue;
+
+                if (DevicePathSubType(node) != MEDIA_HARDDRIVE_DP)
+                        continue;
+
+                hd = (HARDDRIVE_DEVICE_PATH*) node;
+                hd->PartitionNumber = found_partition_number;
+                hd->PartitionStart = found_partition_start;
+                hd->PartitionSize = found_partition_size;
+                CopyMem(hd->Signature, found_partition_signature, sizeof(hd->Signature));
+                hd->MBRType = MBR_TYPE_EFI_PARTITION_TABLE_HEADER;
+                hd->SignatureType = SIGNATURE_TYPE_GUID;
+        }
+
+        r = uefi_call_wrapper(BS->LocateDevicePath, 3, &BlockIoProtocol, &copy, &new_device);
+        if (EFI_ERROR(r))
+                return;
+
+        root_dir = LibOpenRoot(new_device);
+        if (!root_dir)
+                return;
+
+        config_entry_add_linux(config, new_device, root_dir);
+        config_load_entries(config, new_device, root_dir, NULL);
+}
+
 static EFI_STATUS image_start(
                 EFI_HANDLE parent_image,
                 const Config *config,
@@ -2147,6 +2336,9 @@ EFI_STATUS efi_main(EFI_HANDLE image, EFI_SYSTEM_TABLE *sys_table) {
         /* scan /loader/entries/\*.conf files */
         config_load_entries(&config, loaded_image->DeviceHandle, root_dir, loaded_image_path);
 
+        /* Similar, but on any XBOOTLDR partition */
+        config_load_xbootldr(&config, loaded_image->DeviceHandle);
+
         /* sort entries after version number */
         config_sort_entries(&config);
 
diff --git a/src/boot/efi/crc32.c b/src/boot/efi/crc32.c
new file mode 100644 (file)
index 0000000..46b9aee
--- /dev/null
@@ -0,0 +1,142 @@
+/* This is copied from util-linux, which in turn copied in the version from Gary S. Brown */
+
+/*
+ *  COPYRIGHT (C) 1986 Gary S. Brown.  You may use this program, or
+ *  code or tables extracted from it, as desired without restriction.
+ *
+ *  First, the polynomial itself and its table of feedback terms.  The
+ *  polynomial is
+ *  X^32+X^26+X^23+X^22+X^16+X^12+X^11+X^10+X^8+X^7+X^5+X^4+X^2+X^1+X^0
+ *
+ *  Note that we take it "backwards" and put the highest-order term in
+ *  the lowest-order bit.  The X^32 term is "implied"; the LSB is the
+ *  X^31 term, etc.  The X^0 term (usually shown as "+1") results in
+ *  the MSB being 1.
+ *
+ *  Note that the usual hardware shift register implementation, which
+ *  is what we're using (we're merely optimizing it by doing eight-bit
+ *  chunks at a time) shifts bits into the lowest-order term.  In our
+ *  implementation, that means shifting towards the right.  Why do we
+ *  do it this way?  Because the calculated CRC must be transmitted in
+ *  order from highest-order term to lowest-order term.  UARTs transmit
+ *  characters in order from LSB to MSB.  By storing the CRC this way,
+ *  we hand it to the UART in the order low-byte to high-byte; the UART
+ *  sends each low-bit to high-bit; and the result is transmission bit
+ *  by bit from highest- to lowest-order term without requiring any bit
+ *  shuffling on our part.  Reception works similarly.
+ *
+ *  The feedback terms table consists of 256, 32-bit entries.  Notes
+ *
+ *      The table can be generated at runtime if desired; code to do so
+ *      is shown later.  It might not be obvious, but the feedback
+ *      terms simply represent the results of eight shift/xor opera-
+ *      tions for all combinations of data and CRC register values.
+ *
+ *      The values must be right-shifted by eight bits by the "updcrc"
+ *      logic; the shift must be unsigned (bring in zeroes).  On some
+ *      hardware you could probably optimize the shift in assembler by
+ *      using byte-swap instructions.
+ *      polynomial $edb88320
+ *
+ */
+
+#include "crc32.h"
+
+static const UINT32 crc32_tab[] = {
+        0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
+        0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
+        0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,
+        0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL,
+        0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L,
+        0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L,
+        0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L,
+        0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL,
+        0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L,
+        0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL,
+        0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L,
+        0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L,
+        0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L,
+        0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL,
+        0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL,
+        0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L,
+        0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL,
+        0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L,
+        0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L,
+        0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L,
+        0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL,
+        0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L,
+        0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L,
+        0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL,
+        0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L,
+        0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L,
+        0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L,
+        0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L,
+        0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L,
+        0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL,
+        0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL,
+        0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L,
+        0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L,
+        0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL,
+        0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL,
+        0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L,
+        0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL,
+        0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L,
+        0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL,
+        0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L,
+        0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL,
+        0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L,
+        0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L,
+        0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL,
+        0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L,
+        0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L,
+        0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L,
+        0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L,
+        0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L,
+        0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L,
+        0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
+        0x2d02ef8dL
+};
+
+static inline UINT32 crc32_add_char(UINT32 crc, UINT8 c) {
+        return crc32_tab[(crc ^ c) & 0xff] ^ (crc >> 8);
+}
+
+/*
+ * This a generic crc32() function, it takes seed as an argument,
+ * and does __not__ xor at the end. Then individual users can do
+ * whatever they need.
+ */
+UINT32 crc32(UINT32 seed, const VOID *buf, UINTN len) {
+        const UINT8 *p = buf;
+        UINT32 crc = seed;
+
+        while (len > 0) {
+                crc = crc32_add_char(crc, *p++);
+                len--;
+        }
+
+        return crc;
+}
+
+UINT32 crc32_exclude_offset(
+                UINT32 seed,
+                const VOID *buf,
+                UINTN len,
+                UINTN exclude_off,
+                UINTN exclude_len) {
+
+        const UINT8 *p = buf;
+        UINT32 crc = seed;
+        UINTN i;
+
+        for (i = 0; i < len; i++) {
+                UINT8 x = *p++;
+
+                if (i >= exclude_off && i < exclude_off + exclude_len)
+                        x = 0;
+
+                crc = crc32_add_char(crc, x);
+        }
+
+        return crc;
+}
diff --git a/src/boot/efi/crc32.h b/src/boot/efi/crc32.h
new file mode 100644 (file)
index 0000000..64150ee
--- /dev/null
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+#pragma once
+
+#include <efi.h>
+#include <efilib.h>
+
+UINT32 crc32(UINT32 seed, const VOID *buf, UINTN len);
+UINT32 crc32_exclude_offset(UINT32 seed, const VOID *buf, UINTN len, UINTN exclude_off, UINTN exclude_len);
index 2140151..67b4331 100644 (file)
@@ -2,6 +2,7 @@
 
 efi_headers = files('''
         console.h
+        crc32.h
         disk.h
         graphics.h
         linux.h
@@ -24,6 +25,7 @@ systemd_boot_sources = '''
         boot.c
         console.c
         shim.c
+        crc32.c
 '''.split()
 
 stub_sources = '''