// SPDX-License-Identifier: GPL-2.0-or-later /************************************************************ * EFI GUID Partition Table handling * * http://www.uefi.org/specs/ * http://www.intel.com/technology/efi/ * * efi.[ch] by Matt Domsch <[email protected]> * Copyright 2000,2001,2002,2004 Dell Inc. * * TODO: * * Changelog: * Mon August 5th, 2013 Davidlohr Bueso <[email protected]> * - detect hybrid MBRs, tighter pMBR checking & cleanups. * * Mon Nov 09 2004 Matt Domsch <[email protected]> * - test for valid PMBR and valid PGPT before ever reading * AGPT, allow override with 'gpt' kernel command line option. * - check for first/last_usable_lba outside of size of disk * * Tue Mar 26 2002 Matt Domsch <[email protected]> * - Ported to 2.5.7-pre1 and 2.5.7-dj2 * - Applied patch to avoid fault in alternate header handling * - cleaned up find_valid_gpt * - On-disk structure and copy in memory is *always* LE now - * swab fields as needed * - remove print_gpt_header() * - only use first max_p partition entries, to keep the kernel minor number * and partition numbers tied. * * Mon Feb 04 2002 Matt Domsch <[email protected]> * - Removed __PRIPTR_PREFIX - not being used * * Mon Jan 14 2002 Matt Domsch <[email protected]> * - Ported to 2.5.2-pre11 + library crc32 patch Linus applied * * Thu Dec 6 2001 Matt Domsch <[email protected]> * - Added compare_gpts(). * - moved le_efi_guid_to_cpus() back into this file. GPT is the only * thing that keeps EFI GUIDs on disk. * - Changed gpt structure names and members to be simpler and more Linux-like. * * Wed Oct 17 2001 Matt Domsch <[email protected]> * - Removed CONFIG_DEVFS_VOLUMES_UUID code entirely per Martin Wilck * * Wed Oct 10 2001 Matt Domsch <[email protected]> * - Changed function comments to DocBook style per Andreas Dilger suggestion. * * Mon Oct 08 2001 Matt Domsch <[email protected]> * - Change read_lba() to use the page cache per Al Viro's work. * - print u64s properly on all architectures * - fixed debug_printk(), now Dprintk() * * Mon Oct 01 2001 Matt Domsch <[email protected]> * - Style cleanups * - made most functions static * - Endianness addition * - remove test for second alternate header, as it's not per spec, * and is unnecessary. There's now a method to read/write the last * sector of an odd-sized disk from user space. No tools have ever * been released which used this code, so it's effectively dead. * - Per Asit Mallick of Intel, added a test for a valid PMBR. * - Added kernel command line option 'gpt' to override valid PMBR test. * * Wed Jun 6 2001 Martin Wilck <[email protected]> * - added devfs volume UUID support (/dev/volumes/uuids) for * mounting file systems by the partition GUID. * * Tue Dec 5 2000 Matt Domsch <[email protected]> * - Moved crc32() to linux/lib, added efi_crc32(). * * Thu Nov 30 2000 Matt Domsch <[email protected]> * - Replaced Intel's CRC32 function with an equivalent * non-license-restricted version. * * Wed Oct 25 2000 Matt Domsch <[email protected]> * - Fixed the last_lba() call to return the proper last block * * Thu Oct 12 2000 Matt Domsch <[email protected]> * - Thanks to Andries Brouwer for his debugging assistance. * - Code works, detects all the partitions. * ************************************************************/ #include <linux/kernel.h> #include <linux/crc32.h> #include <linux/ctype.h> #include <linux/math64.h> #include <linux/slab.h> #include "check.h" #include "efi.h" /* This allows a kernel command line option 'gpt' to override * the test for invalid PMBR. Not __initdata because reloading * the partition tables happens after init too. */ static int force_gpt; static int __init force_gpt_fn(char *str) { … } __setup(…); /** * efi_crc32() - EFI version of crc32 function * @buf: buffer to calculate crc32 of * @len: length of buf * * Description: Returns EFI-style CRC32 value for @buf * * This function uses the little endian Ethernet polynomial * but seeds the function with ~0, and xor's with ~0 at the end. * Note, the EFI Specification, v1.02, has a reference to * Dr. Dobbs Journal, May 1994 (actually it's in May 1992). */ static inline u32 efi_crc32(const void *buf, unsigned long len) { … } /** * last_lba(): return number of last logical block of device * @disk: block device * * Description: Returns last LBA value on success, 0 on error. * This is stored (by sd and ide-geometry) in * the part[0] entry for this disk, and is the number of * physical sectors available on the disk. */ static u64 last_lba(struct gendisk *disk) { … } static inline int pmbr_part_valid(gpt_mbr_record *part) { … } /** * is_pmbr_valid(): test Protective MBR for validity * @mbr: pointer to a legacy mbr structure * @total_sectors: amount of sectors in the device * * Description: Checks for a valid protective or hybrid * master boot record (MBR). The validity of a pMBR depends * on all of the following properties: * 1) MSDOS signature is in the last two bytes of the MBR * 2) One partition of type 0xEE is found * * In addition, a hybrid MBR will have up to three additional * primary partitions, which point to the same space that's * marked out by up to three GPT partitions. * * Returns 0 upon invalid MBR, or GPT_MBR_PROTECTIVE or * GPT_MBR_HYBRID depending on the device layout. */ static int is_pmbr_valid(legacy_mbr *mbr, sector_t total_sectors) { … } /** * read_lba(): Read bytes from disk, starting at given LBA * @state: disk parsed partitions * @lba: the Logical Block Address of the partition table * @buffer: destination buffer * @count: bytes to read * * Description: Reads @count bytes from @state->disk into @buffer. * Returns number of bytes read on success, 0 on error. */ static size_t read_lba(struct parsed_partitions *state, u64 lba, u8 *buffer, size_t count) { … } /** * alloc_read_gpt_entries(): reads partition entries from disk * @state: disk parsed partitions * @gpt: GPT header * * Description: Returns ptes on success, NULL on error. * Allocates space for PTEs based on information found in @gpt. * Notes: remember to free pte when you're done! */ static gpt_entry *alloc_read_gpt_entries(struct parsed_partitions *state, gpt_header *gpt) { … } /** * alloc_read_gpt_header(): Allocates GPT header, reads into it from disk * @state: disk parsed partitions * @lba: the Logical Block Address of the partition table * * Description: returns GPT header on success, NULL on error. Allocates * and fills a GPT header starting at @ from @state->disk. * Note: remember to free gpt when finished with it. */ static gpt_header *alloc_read_gpt_header(struct parsed_partitions *state, u64 lba) { … } /** * is_gpt_valid() - tests one GPT header and PTEs for validity * @state: disk parsed partitions * @lba: logical block address of the GPT header to test * @gpt: GPT header ptr, filled on return. * @ptes: PTEs ptr, filled on return. * * Description: returns 1 if valid, 0 on error. * If valid, returns pointers to newly allocated GPT header and PTEs. */ static int is_gpt_valid(struct parsed_partitions *state, u64 lba, gpt_header **gpt, gpt_entry **ptes) { … } /** * is_pte_valid() - tests one PTE for validity * @pte:pte to check * @lastlba: last lba of the disk * * Description: returns 1 if valid, 0 on error. */ static inline int is_pte_valid(const gpt_entry *pte, const u64 lastlba) { … } /** * compare_gpts() - Search disk for valid GPT headers and PTEs * @pgpt: primary GPT header * @agpt: alternate GPT header * @lastlba: last LBA number * * Description: Returns nothing. Sanity checks pgpt and agpt fields * and prints warnings on discrepancies. * */ static void compare_gpts(gpt_header *pgpt, gpt_header *agpt, u64 lastlba) { … } /** * find_valid_gpt() - Search disk for valid GPT headers and PTEs * @state: disk parsed partitions * @gpt: GPT header ptr, filled on return. * @ptes: PTEs ptr, filled on return. * * Description: Returns 1 if valid, 0 on error. * If valid, returns pointers to newly allocated GPT header and PTEs. * Validity depends on PMBR being valid (or being overridden by the * 'gpt' kernel command line option) and finding either the Primary * GPT header and PTEs valid, or the Alternate GPT header and PTEs * valid. If the Primary GPT header is not valid, the Alternate GPT header * is not checked unless the 'gpt' kernel command line option is passed. * This protects against devices which misreport their size, and forces * the user to decide to use the Alternate GPT. */ static int find_valid_gpt(struct parsed_partitions *state, gpt_header **gpt, gpt_entry **ptes) { … } /** * utf16_le_to_7bit(): Naively converts a UTF-16LE string to 7-bit ASCII characters * @in: input UTF-16LE string * @size: size of the input string * @out: output string ptr, should be capable to store @size+1 characters * * Description: Converts @size UTF16-LE symbols from @in string to 7-bit * ASCII characters and stores them to @out. Adds trailing zero to @out array. */ static void utf16_le_to_7bit(const __le16 *in, unsigned int size, u8 *out) { … } /** * efi_partition - scan for GPT partitions * @state: disk parsed partitions * * Description: called from check.c, if the disk contains GPT * partitions, sets up partition entries in the kernel. * * If the first block on the disk is a legacy MBR, * it will get handled by msdos_partition(). * If it's a Protective MBR, we'll handle it here. * * We do not create a Linux partition for GPT, but * only for the actual data partitions. * Returns: * -1 if unable to read the partition table * 0 if this isn't our partition table * 1 if successful * */ int efi_partition(struct parsed_partitions *state) { … }
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