@@ -63,6 +71,17 @@ static inline unsigned long my_r2(const struct elf_info *elf_info)
return elf_info->sechdrs[elf_info->toc_section].sh_addr + 0x8000;
}
+static inline bool elf_is_elf_file(const struct elfhdr *ehdr)
+{
+ return memcmp(ehdr->e_ident, ELFMAG, SELFMAG) == 0;
+}
+
+int elf_read_from_buffer(const char *buf, size_t len, struct elfhdr *ehdr,
+ struct elf_info *elf_info);
+void elf_init_elf_info(const struct elfhdr *ehdr, struct elf_shdr *sechdrs,
+ struct elf_info *elf_info);
+void elf_free_info(struct elf_info *elf_info);
+
int elf64_apply_relocate_add(const struct elf_info *elf_info,
const char *strtab, const Elf64_Rela *rela,
unsigned int num_rela, void *syms_base,@@ -0,0 +1,476 @@
+/*
+ * Utility functions to work with ELF files.
+ *
+ * Copyright (C) 2016, IBM Corporation
+ *
+ * Based on kexec-tools' kexec-elf.c. Heavily modified for the
+ * kernel by Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation (version 2 of the License).
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/slab.h>
+#include <asm/elf_util.h>
+#include <asm-generic/module.h>
+
+#if ELF_CLASS == ELFCLASS32
+#define elf_addr_to_cpu elf32_to_cpu
+
+#ifndef Elf_Rel
+#define Elf_Rel Elf32_Rel
+#endif /* Elf_Rel */
+#else /* ELF_CLASS == ELFCLASS32 */
+#define elf_addr_to_cpu elf64_to_cpu
+
+#ifndef Elf_Rel
+#define Elf_Rel Elf64_Rel
+#endif /* Elf_Rel */
+
+static uint64_t elf64_to_cpu(const struct elfhdr *ehdr, uint64_t value)
+{
+ if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
+ value = le64_to_cpu(value);
+ else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
+ value = be64_to_cpu(value);
+
+ return value;
+}
+#endif /* ELF_CLASS == ELFCLASS32 */
+
+static uint16_t elf16_to_cpu(const struct elfhdr *ehdr, uint16_t value)
+{
+ if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
+ value = le16_to_cpu(value);
+ else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
+ value = be16_to_cpu(value);
+
+ return value;
+}
+
+static uint32_t elf32_to_cpu(const struct elfhdr *ehdr, uint32_t value)
+{
+ if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
+ value = le32_to_cpu(value);
+ else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
+ value = be32_to_cpu(value);
+
+ return value;
+}
+
+/**
+ * elf_is_ehdr_sane - check that it is safe to use the ELF header
+ * @buf_len: size of the buffer in which the ELF file is loaded.
+ */
+static bool elf_is_ehdr_sane(const struct elfhdr *ehdr, size_t buf_len)
+{
+ if (ehdr->e_phnum > 0 && ehdr->e_phentsize != sizeof(struct elf_phdr)) {
+ pr_debug("Bad program header size.\n");
+ return false;
+ } else if (ehdr->e_shnum > 0 &&
+ ehdr->e_shentsize != sizeof(struct elf_shdr)) {
+ pr_debug("Bad section header size.\n");
+ return false;
+ } else if (ehdr->e_ident[EI_VERSION] != EV_CURRENT ||
+ ehdr->e_version != EV_CURRENT) {
+ pr_debug("Unknown ELF version.\n");
+ return false;
+ }
+
+ if (ehdr->e_phoff > 0 && ehdr->e_phnum > 0) {
+ size_t phdr_size;
+
+ /*
+ * e_phnum is at most 65535 so calculating the size of the
+ * program header cannot overflow.
+ */
+ phdr_size = sizeof(struct elf_phdr) * ehdr->e_phnum;
+
+ /* Sanity check the program header table location. */
+ if (ehdr->e_phoff + phdr_size < ehdr->e_phoff) {
+ pr_debug("Program headers at invalid location.\n");
+ return false;
+ } else if (ehdr->e_phoff + phdr_size > buf_len) {
+ pr_debug("Program headers truncated.\n");
+ return false;
+ }
+ }
+
+ if (ehdr->e_shoff > 0 && ehdr->e_shnum > 0) {
+ size_t shdr_size;
+
+ /*
+ * e_shnum is at most 65536 so calculating
+ * the size of the section header cannot overflow.
+ */
+ shdr_size = sizeof(struct elf_shdr) * ehdr->e_shnum;
+
+ /* Sanity check the section header table location. */
+ if (ehdr->e_shoff + shdr_size < ehdr->e_shoff) {
+ pr_debug("Section headers at invalid location.\n");
+ return false;
+ } else if (ehdr->e_shoff + shdr_size > buf_len) {
+ pr_debug("Section headers truncated.\n");
+ return false;
+ }
+ }
+
+ return true;
+}
+
+static int elf_read_ehdr(const char *buf, size_t len, struct elfhdr *ehdr)
+{
+ struct elfhdr *buf_ehdr;
+
+ if (len < sizeof(*buf_ehdr)) {
+ pr_debug("Buffer is too small to hold ELF header.\n");
+ return -ENOEXEC;
+ }
+
+ memset(ehdr, 0, sizeof(*ehdr));
+ memcpy(ehdr->e_ident, buf, sizeof(ehdr->e_ident));
+ if (!elf_is_elf_file(ehdr)) {
+ pr_debug("No ELF header magic.\n");
+ return -ENOEXEC;
+ }
+
+ if (ehdr->e_ident[EI_CLASS] != ELF_CLASS) {
+ pr_debug("Not a supported ELF class.\n");
+ return -1;
+ } else if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB &&
+ ehdr->e_ident[EI_DATA] != ELFDATA2MSB) {
+ pr_debug("Not a supported ELF data format.\n");
+ return -ENOEXEC;
+ }
+
+ buf_ehdr = (struct elfhdr *) buf;
+ if (elf16_to_cpu(ehdr, buf_ehdr->e_ehsize) != sizeof(*buf_ehdr)) {
+ pr_debug("Bad ELF header size.\n");
+ return -ENOEXEC;
+ }
+
+ ehdr->e_type = elf16_to_cpu(ehdr, buf_ehdr->e_type);
+ ehdr->e_machine = elf16_to_cpu(ehdr, buf_ehdr->e_machine);
+ ehdr->e_version = elf32_to_cpu(ehdr, buf_ehdr->e_version);
+ ehdr->e_entry = elf_addr_to_cpu(ehdr, buf_ehdr->e_entry);
+ ehdr->e_phoff = elf_addr_to_cpu(ehdr, buf_ehdr->e_phoff);
+ ehdr->e_shoff = elf_addr_to_cpu(ehdr, buf_ehdr->e_shoff);
+ ehdr->e_flags = elf32_to_cpu(ehdr, buf_ehdr->e_flags);
+ ehdr->e_phentsize = elf16_to_cpu(ehdr, buf_ehdr->e_phentsize);
+ ehdr->e_phnum = elf16_to_cpu(ehdr, buf_ehdr->e_phnum);
+ ehdr->e_shentsize = elf16_to_cpu(ehdr, buf_ehdr->e_shentsize);
+ ehdr->e_shnum = elf16_to_cpu(ehdr, buf_ehdr->e_shnum);
+ ehdr->e_shstrndx = elf16_to_cpu(ehdr, buf_ehdr->e_shstrndx);
+
+ return elf_is_ehdr_sane(ehdr, len) ? 0 : -ENOEXEC;
+}
+
+/**
+ * elf_is_phdr_sane - check that it is safe to use the program header
+ * @buf_len: size of the buffer in which the ELF file is loaded.
+ */
+static bool elf_is_phdr_sane(const struct elf_phdr *phdr, size_t buf_len)
+{
+
+ if (phdr->p_offset + phdr->p_filesz < phdr->p_offset) {
+ pr_debug("ELF segment location wraps around.\n");
+ return false;
+ } else if (phdr->p_offset + phdr->p_filesz > buf_len) {
+ pr_debug("ELF segment not in file.\n");
+ return false;
+ } else if (phdr->p_paddr + phdr->p_memsz < phdr->p_paddr) {
+ pr_debug("ELF segment address wraps around.\n");
+ return false;
+ }
+
+ return true;
+}
+
+static int elf_read_phdr(const char *buf, size_t len, struct elf_info *elf_info,
+ int idx)
+{
+ /* Override the const in proghdrs, we are the ones doing the loading. */
+ struct elf_phdr *phdr = (struct elf_phdr *) &elf_info->proghdrs[idx];
+ const char *pbuf;
+ struct elf_phdr *buf_phdr;
+
+ pbuf = buf + elf_info->ehdr->e_phoff + (idx * sizeof(*buf_phdr));
+ buf_phdr = (struct elf_phdr *) pbuf;
+
+ phdr->p_type = elf32_to_cpu(elf_info->ehdr, buf_phdr->p_type);
+ phdr->p_offset = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_offset);
+ phdr->p_paddr = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_paddr);
+ phdr->p_vaddr = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_vaddr);
+ phdr->p_flags = elf32_to_cpu(elf_info->ehdr, buf_phdr->p_flags);
+
+ /*
+ * The following fields have a type equivalent to Elf_Addr
+ * both in 32 bit and 64 bit ELF.
+ */
+ phdr->p_filesz = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_filesz);
+ phdr->p_memsz = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_memsz);
+ phdr->p_align = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_align);
+
+ return elf_is_phdr_sane(phdr, len) ? 0 : -ENOEXEC;
+}
+
+/**
+ * elf_read_phdrs - read the program headers from the buffer
+ *
+ * This function assumes that the program header table was checked for sanity.
+ * Use elf_is_ehdr_sane() if it wasn't.
+ */
+static int elf_read_phdrs(const char *buf, size_t len,
+ struct elf_info *elf_info)
+{
+ size_t phdr_size, i;
+ const struct elfhdr *ehdr = elf_info->ehdr;
+
+ /*
+ * e_phnum is at most 65535 so calculating the size of the
+ * program header cannot overflow.
+ */
+ phdr_size = sizeof(struct elf_phdr) * ehdr->e_phnum;
+
+ elf_info->proghdrs = kzalloc(phdr_size, GFP_KERNEL);
+ if (!elf_info->proghdrs)
+ return -ENOMEM;
+
+ for (i = 0; i < ehdr->e_phnum; i++) {
+ int ret;
+
+ ret = elf_read_phdr(buf, len, elf_info, i);
+ if (ret) {
+ kfree(elf_info->proghdrs);
+ elf_info->proghdrs = NULL;
+ return ret;
+ }
+ }
+
+ return 0;
+}
+
+/**
+ * elf_is_shdr_sane - check that it is safe to use the section header
+ * @buf_len: size of the buffer in which the ELF file is loaded.
+ */
+static bool elf_is_shdr_sane(const struct elf_shdr *shdr, size_t buf_len)
+{
+ bool size_ok;
+
+ /* SHT_NULL headers have undefined values, so we can't check them. */
+ if (shdr->sh_type == SHT_NULL)
+ return true;
+
+ /* Now verify sh_entsize */
+ switch (shdr->sh_type) {
+ case SHT_SYMTAB:
+ size_ok = shdr->sh_entsize == sizeof(Elf_Sym);
+ break;
+ case SHT_RELA:
+ size_ok = shdr->sh_entsize == sizeof(Elf_Rela);
+ break;
+ case SHT_DYNAMIC:
+ size_ok = shdr->sh_entsize == sizeof(Elf_Dyn);
+ break;
+ case SHT_REL:
+ size_ok = shdr->sh_entsize == sizeof(Elf_Rel);
+ break;
+ case SHT_NOTE:
+ case SHT_PROGBITS:
+ case SHT_HASH:
+ case SHT_NOBITS:
+ default:
+ /*
+ * This is a section whose entsize requirements
+ * I don't care about. If I don't know about
+ * the section I can't care about it's entsize
+ * requirements.
+ */
+ size_ok = true;
+ break;
+ }
+
+ if (!size_ok) {
+ pr_debug("ELF section with wrong entry size.\n");
+ return false;
+ } else if (shdr->sh_addr + shdr->sh_size < shdr->sh_addr) {
+ pr_debug("ELF section address wraps around.\n");
+ return false;
+ }
+
+ if (shdr->sh_type != SHT_NOBITS) {
+ if (shdr->sh_offset + shdr->sh_size < shdr->sh_offset) {
+ pr_debug("ELF section location wraps around.\n");
+ return false;
+ } else if (shdr->sh_offset + shdr->sh_size > buf_len) {
+ pr_debug("ELF section not in file.\n");
+ return false;
+ }
+ }
+
+ return true;
+}
+
+static int elf_read_shdr(const char *buf, size_t len, struct elf_info *elf_info,
+ int idx)
+{
+ struct elf_shdr *shdr = &elf_info->sechdrs[idx];
+ const struct elfhdr *ehdr = elf_info->ehdr;
+ const char *sbuf;
+ struct elf_shdr *buf_shdr;
+
+ sbuf = buf + ehdr->e_shoff + idx * sizeof(*buf_shdr);
+ buf_shdr = (struct elf_shdr *) sbuf;
+
+ shdr->sh_name = elf32_to_cpu(ehdr, buf_shdr->sh_name);
+ shdr->sh_type = elf32_to_cpu(ehdr, buf_shdr->sh_type);
+ shdr->sh_addr = elf_addr_to_cpu(ehdr, buf_shdr->sh_addr);
+ shdr->sh_offset = elf_addr_to_cpu(ehdr, buf_shdr->sh_offset);
+ shdr->sh_link = elf32_to_cpu(ehdr, buf_shdr->sh_link);
+ shdr->sh_info = elf32_to_cpu(ehdr, buf_shdr->sh_info);
+
+ /*
+ * The following fields have a type equivalent to Elf_Addr
+ * both in 32 bit and 64 bit ELF.
+ */
+ shdr->sh_flags = elf_addr_to_cpu(ehdr, buf_shdr->sh_flags);
+ shdr->sh_size = elf_addr_to_cpu(ehdr, buf_shdr->sh_size);
+ shdr->sh_addralign = elf_addr_to_cpu(ehdr, buf_shdr->sh_addralign);
+ shdr->sh_entsize = elf_addr_to_cpu(ehdr, buf_shdr->sh_entsize);
+
+ return elf_is_shdr_sane(shdr, len) ? 0 : -ENOEXEC;
+}
+
+/**
+ * elf_read_shdrs - read the section headers from the buffer
+ *
+ * This function assumes that the section header table was checked for sanity.
+ * Use elf_is_ehdr_sane() if it wasn't.
+ */
+static int elf_read_shdrs(const char *buf, size_t len,
+ struct elf_info *elf_info)
+{
+ size_t shdr_size, i;
+
+ /*
+ * e_shnum is at most 65536 so calculating
+ * the size of the section header cannot overflow.
+ */
+ shdr_size = sizeof(struct elf_shdr) * elf_info->ehdr->e_shnum;
+
+ elf_info->sechdrs = kzalloc(shdr_size, GFP_KERNEL);
+ if (!elf_info->sechdrs)
+ return -ENOMEM;
+
+ for (i = 0; i < elf_info->ehdr->e_shnum; i++) {
+ int ret;
+
+ ret = elf_read_shdr(buf, len, elf_info, i);
+ if (ret) {
+ kfree(elf_info->sechdrs);
+ elf_info->sechdrs = NULL;
+ return ret;
+ }
+ }
+
+ return 0;
+}
+
+/**
+ * elf_read_from_buffer - read ELF file and sets up ELF header and ELF info
+ * @buf: Buffer to read ELF file from.
+ * @len: Size of @buf.
+ * @ehdr: Pointer to existing struct which will be populated.
+ * @elf_info: Pointer to existing struct which will be populated.
+ *
+ * This function allows reading ELF files with different byte order than
+ * the kernel, byte-swapping the fields as needed.
+ *
+ * Return:
+ * On success returns 0, and the caller should call elf_free_info(elf_info) to
+ * free the memory allocated for the section and program headers.
+ */
+int elf_read_from_buffer(const char *buf, size_t len, struct elfhdr *ehdr,
+ struct elf_info *elf_info)
+{
+ int ret;
+
+ ret = elf_read_ehdr(buf, len, ehdr);
+ if (ret)
+ return ret;
+
+ elf_info->buffer = buf;
+ elf_info->ehdr = ehdr;
+ if (ehdr->e_phoff > 0 && ehdr->e_phnum > 0) {
+ ret = elf_read_phdrs(buf, len, elf_info);
+ if (ret)
+ return ret;
+ }
+ if (ehdr->e_shoff > 0 && ehdr->e_shnum > 0) {
+ ret = elf_read_shdrs(buf, len, elf_info);
+ if (ret) {
+ kfree(elf_info->proghdrs);
+ return ret;
+ }
+ }
+
+ return 0;
+}
+
+/**
+ * elf_init_elf_info - initialize elf_info from existing information
+ * @ehdr: Pointer to already loaded ELF header.
+ * @sechdrs: Pointer to already loaded section headers contents.
+ * @elf_info: Pointer to existing struct which will be populated.
+ *
+ * If the ELF binary was not loaded using elf_read_from_buffer, this function
+ * can be used to obtain a struct elf_info for use with other ELF utility
+ * functions.
+ *
+ * The caller is responsible for managing @sechdrs memory, users of this
+ * function don't need to call elf_free_info() if they free this memory
+ * separately.
+ */
+void elf_init_elf_info(const struct elfhdr *ehdr, struct elf_shdr *sechdrs,
+ struct elf_info *elf_info)
+{
+ int i;
+ const char *shstrtab;
+
+ memset(elf_info, 0, sizeof(*elf_info));
+
+ /* Section header string table. */
+ shstrtab = (const char *) sechdrs[ehdr->e_shstrndx].sh_offset;
+
+ for (i = 0; i < ehdr->e_shnum; i++) {
+ if (sechdrs[i].sh_size == 0)
+ continue;
+
+ if (!strcmp(&shstrtab[sechdrs[i].sh_name], ".stubs"))
+ elf_info->stubs_section = i;
+ else if (!strcmp(&shstrtab[sechdrs[i].sh_name], ".toc"))
+ elf_info->toc_section = i;
+ }
+
+ elf_info->ehdr = ehdr;
+ elf_info->sechdrs = sechdrs;
+}
+
+/**
+ * elf_free_info - free memory allocated by elf_read_from_buffer
+ */
+void elf_free_info(struct elf_info *elf_info)
+{
+ kfree(elf_info->proghdrs);
+ kfree(elf_info->sechdrs);
+ memset(elf_info, 0, sizeof(*elf_info));
+}