1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 3 #ifndef ELFPARSING_H 4 #define ELFPARSING_H 5 6 #include "elf.h" 7 #include "common.h" 8 9 struct parsed_elf { 10 Elf64_Ehdr ehdr; 11 Elf64_Phdr *phdr; 12 Elf64_Shdr *shdr; 13 /* 14 * The relocs array contains pointers to arrays of relocation 15 * structures. Each index into the relocs array corresponds to its 16 * corresponding section index. i.e. if a section i is of type SHT_REL 17 * or SHT_RELA then the corresponding index into the relocs array will 18 * contain the associated relocations. Otherwise thee entry will be 19 * NULL. 20 */ 21 Elf64_Rela **relocs; 22 /* 23 * Similarly to the relocs array the strtabs array consists of an 24 * array of pointers where each entry represents a potential struct 25 * buffer pointer. Only setions of type SHT_STRTAB will have a non-NULL 26 * entry. 27 */ 28 struct buffer **strtabs; 29 /* Parsed symbols. */ 30 Elf64_Sym *syms; 31 }; 32 33 #define ELF_PARSE_PHDR (1 << 0) 34 #define ELF_PARSE_SHDR (1 << 1) 35 #define ELF_PARSE_RELOC (1 << 2) 36 #define ELF_PARSE_STRTAB (1 << 3) 37 #define ELF_PARSE_SYMTAB (1 << 4) 38 39 #define ELF_PARSE_ALL (-1) 40 41 /* 42 * Parse an ELF file contained within provide struct buffer. The ELF header 43 * is always parsed while the flags value containing the ELF_PARSE_* values 44 * determine if other parts of the ELF file will be parsed as well. 45 * Returns 0 on success, < 0 error. 46 */ 47 int parse_elf(const struct buffer *pinput, struct parsed_elf *pelf, int flags); 48 49 /* 50 * Clean up memory associated with parsed_elf. 51 */ 52 void parsed_elf_destroy(struct parsed_elf *pelf); 53 54 55 int 56 elf_headers(const struct buffer *pinput, 57 Elf64_Ehdr *ehdr, 58 Elf64_Phdr **pphdr, 59 Elf64_Shdr **pshdr); 60 61 /* ELF writing support. */ 62 struct elf_writer; 63 64 /* 65 * Initialize a 64-bit ELF header provided the inputs. While the structure 66 * is a 64-bit header one can specify a 32-bit machine. The 64-bit version 67 * is just used as a common structure. If one wants to specify the entry 68 * point, for example, the caller can set it after filling in the common 69 * bits. The machine, nbits, and endian values should be from the ELF 70 * definitions (e.g. EM_386, ELFCLASS32, and ELFDATA2LSB) found in elf.h 71 * with no endian conversion required. 72 */ 73 void elf_init_eheader(Elf64_Ehdr *ehdr, int machine, int nbits, int endian); 74 75 /* 76 * Initialize a new ELF writer. Default machine type, endianness, etc is 77 * copied from the passed in Elf64_Ehdr. Returns NULL on failure, valid 78 * pointer on success. 79 */ 80 struct elf_writer *elf_writer_init(const Elf64_Ehdr *ehdr); 81 82 /* 83 * Clean up any internal state represented by ew. Aftewards the elf_writer 84 * is invalid. 85 * It is safe to call elf_writer_destroy with ew as NULL. It returns without 86 * performing any action. 87 */ 88 void elf_writer_destroy(struct elf_writer *ew); 89 90 /* 91 * Add a section to the ELF file. Section type, flags, and memsize are 92 * maintained from the passed in Elf64_Shdr. The buffer represents the 93 * content of the section while the name is the name of section itself. 94 * Returns < 0 on error, 0 on success. 95 */ 96 int elf_writer_add_section(struct elf_writer *ew, const Elf64_Shdr *shdr, 97 struct buffer *contents, const char *name); 98 99 /* Add an absolute symbol to the ELF file returning < 0 on error, index of 100 * symbol otherwise. */ 101 int elf_writer_add_symbol(struct elf_writer *ew, const char *name, 102 const char *section_name, 103 Elf64_Addr value, Elf64_Word size, 104 int binding, int type); 105 106 /* Add an absolute relocation referencing the provided symbol name. Returns < 0 107 * on error, 0 on success. */ 108 int elf_writer_add_rel(struct elf_writer *ew, const char *sym, Elf64_Addr addr); 109 110 /* 111 * Serialize the ELF file to the output buffer. Return < 0 on error, 112 * 0 on success. 113 */ 114 int elf_writer_serialize(struct elf_writer *ew, struct buffer *out); 115 116 /* 117 * Calculate the loadable program's file size footprint and alignment requirements. 118 * Returns < 0 on error, 0 on success. 119 */ 120 int elf_program_file_size_align(const struct buffer *input, size_t *file_size, size_t *align); 121 122 #endif /* ELFPARSING_H */ 123