/* * kexec: kexec_file_load system call * * Copyright (C) 2014 Red Hat Inc. * Authors: * Vivek Goyal <vgoyal@redhat.com> * * This source code is licensed under the GNU General Public License, * Version 2. See the file COPYING for more details. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/capability.h> #include <linux/mm.h> #include <linux/file.h> #include <linux/slab.h> #include <linux/kexec.h> #include <linux/mutex.h> #include <linux/list.h> #include <linux/fs.h> #include <linux/ima.h> #include <crypto/hash.h> #include <crypto/sha.h> #include <linux/syscalls.h> #include <linux/vmalloc.h> #include "kexec_internal.h" static int kexec_calculate_store_digests(struct kimage *image); /* Architectures can provide this probe function */ int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf, unsigned long buf_len) { return -ENOEXEC; } void * __weak arch_kexec_kernel_image_load(struct kimage *image) { return ERR_PTR(-ENOEXEC); } int __weak arch_kimage_file_post_load_cleanup(struct kimage *image) { return -EINVAL; } #ifdef CONFIG_KEXEC_VERIFY_SIG int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf, unsigned long buf_len) { return -EKEYREJECTED; } #endif /* Apply relocations of type RELA */ int __weak arch_kexec_apply_relocations_add(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, unsigned int relsec) { pr_err("RELA relocation unsupported.\n"); return -ENOEXEC; } /* Apply relocations of type REL */ int __weak arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, unsigned int relsec) { pr_err("REL relocation unsupported.\n"); return -ENOEXEC; } /* * Free up memory used by kernel, initrd, and command line. This is temporary * memory allocation which is not needed any more after these buffers have * been loaded into separate segments and have been copied elsewhere. */ void kimage_file_post_load_cleanup(struct kimage *image) { struct purgatory_info *pi = &image->purgatory_info; vfree(image->kernel_buf); image->kernel_buf = NULL; vfree(image->initrd_buf); image->initrd_buf = NULL; kfree(image->cmdline_buf); image->cmdline_buf = NULL; vfree(pi->purgatory_buf); pi->purgatory_buf = NULL; vfree(pi->sechdrs); pi->sechdrs = NULL; /* See if architecture has anything to cleanup post load */ arch_kimage_file_post_load_cleanup(image); /* * Above call should have called into bootloader to free up * any data stored in kimage->image_loader_data. It should * be ok now to free it up. */ kfree(image->image_loader_data); image->image_loader_data = NULL; } /* * In file mode list of segments is prepared by kernel. Copy relevant * data from user space, do error checking, prepare segment list */ static int kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd, const char __user *cmdline_ptr, unsigned long cmdline_len, unsigned flags) { int ret = 0; void *ldata; loff_t size; ret = kernel_read_file_from_fd(kernel_fd, &image->kernel_buf, &size, INT_MAX, READING_KEXEC_IMAGE); if (ret) return ret; image->kernel_buf_len = size; /* IMA needs to pass the measurement list to the next kernel. */ ima_add_kexec_buffer(image); /* Call arch image probe handlers */ ret = arch_kexec_kernel_image_probe(image, image->kernel_buf, image->kernel_buf_len); if (ret) goto out; #ifdef CONFIG_KEXEC_VERIFY_SIG ret = arch_kexec_kernel_verify_sig(image, image->kernel_buf, image->kernel_buf_len); if (ret) { pr_debug("kernel signature verification failed.\n"); goto out; } pr_debug("kernel signature verification successful.\n"); #endif /* It is possible that there no initramfs is being loaded */ if (!(flags & KEXEC_FILE_NO_INITRAMFS)) { ret = kernel_read_file_from_fd(initrd_fd, &image->initrd_buf, &size, INT_MAX, READING_KEXEC_INITRAMFS); if (ret) goto out; image->initrd_buf_len = size; } if (cmdline_len) { image->cmdline_buf = memdup_user(cmdline_ptr, cmdline_len); if (IS_ERR(image->cmdline_buf)) { ret = PTR_ERR(image->cmdline_buf); image->cmdline_buf = NULL; goto out; } image->cmdline_buf_len = cmdline_len; /* command line should be a string with last byte null */ if (image->cmdline_buf[cmdline_len - 1] != '\0') { ret = -EINVAL; goto out; } } /* Call arch image load handlers */ ldata = arch_kexec_kernel_image_load(image); if (IS_ERR(ldata)) { ret = PTR_ERR(ldata); goto out; } image->image_loader_data = ldata; out: /* In case of error, free up all allocated memory in this function */ if (ret) kimage_file_post_load_cleanup(image); return ret; } static int kimage_file_alloc_init(struct kimage **rimage, int kernel_fd, int initrd_fd, const char __user *cmdline_ptr, unsigned long cmdline_len, unsigned long flags) { int ret; struct kimage *image; bool kexec_on_panic = flags & KEXEC_FILE_ON_CRASH; image = do_kimage_alloc_init(); if (!image) return -ENOMEM; image->file_mode = 1; if (kexec_on_panic) { /* Enable special crash kernel control page alloc policy. */ image->control_page = crashk_res.start; image->type = KEXEC_TYPE_CRASH; } ret = kimage_file_prepare_segments(image, kernel_fd, initrd_fd, cmdline_ptr, cmdline_len, flags); if (ret) goto out_free_image; ret = sanity_check_segment_list(image); if (ret) goto out_free_post_load_bufs; ret = -ENOMEM; image->control_code_page = kimage_alloc_control_pages(image, get_order(KEXEC_CONTROL_PAGE_SIZE)); if (!image->control_code_page) { pr_err("Could not allocate control_code_buffer\n"); goto out_free_post_load_bufs; } if (!kexec_on_panic) { image->swap_page = kimage_alloc_control_pages(image, 0); if (!image->swap_page) { pr_err("Could not allocate swap buffer\n"); goto out_free_control_pages; } } *rimage = image; return 0; out_free_control_pages: kimage_free_page_list(&image->control_pages); out_free_post_load_bufs: kimage_file_post_load_cleanup(image); out_free_image: kfree(image); return ret; } SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd, unsigned long, cmdline_len, const char __user *, cmdline_ptr, unsigned long, flags) { int ret = 0, i; struct kimage **dest_image, *image; /* We only trust the superuser with rebooting the system. */ if (!capable(CAP_SYS_BOOT) || kexec_load_disabled) return -EPERM; /* Make sure we have a legal set of flags */ if (flags != (flags & KEXEC_FILE_FLAGS)) return -EINVAL; image = NULL; if (!mutex_trylock(&kexec_mutex)) return -EBUSY; dest_image = &kexec_image; if (flags & KEXEC_FILE_ON_CRASH) { dest_image = &kexec_crash_image; if (kexec_crash_image) arch_kexec_unprotect_crashkres(); } if (flags & KEXEC_FILE_UNLOAD) goto exchange; /* * In case of crash, new kernel gets loaded in reserved region. It is * same memory where old crash kernel might be loaded. Free any * current crash dump kernel before we corrupt it. */ if (flags & KEXEC_FILE_ON_CRASH) kimage_free(xchg(&kexec_crash_image, NULL)); ret = kimage_file_alloc_init(&image, kernel_fd, initrd_fd, cmdline_ptr, cmdline_len, flags); if (ret) goto out; ret = machine_kexec_prepare(image); if (ret) goto out; /* * Some architecture(like S390) may touch the crash memory before * machine_kexec_prepare(), we must copy vmcoreinfo data after it. */ ret = kimage_crash_copy_vmcoreinfo(image); if (ret) goto out; ret = kexec_calculate_store_digests(image); if (ret) goto out; for (i = 0; i < image->nr_segments; i++) { struct kexec_segment *ksegment; ksegment = &image->segment[i]; pr_debug("Loading segment %d: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n", i, ksegment->buf, ksegment->bufsz, ksegment->mem, ksegment->memsz); ret = kimage_load_segment(image, &image->segment[i]); if (ret) goto out; } kimage_terminate(image); /* * Free up any temporary buffers allocated which are not needed * after image has been loaded */ kimage_file_post_load_cleanup(image); exchange: image = xchg(dest_image, image); out: if ((flags & KEXEC_FILE_ON_CRASH) && kexec_crash_image) arch_kexec_protect_crashkres(); mutex_unlock(&kexec_mutex); kimage_free(image); return ret; } static int locate_mem_hole_top_down(unsigned long start, unsigned long end, struct kexec_buf *kbuf) { struct kimage *image = kbuf->image; unsigned long temp_start, temp_end; temp_end = min(end, kbuf->buf_max); temp_start = temp_end - kbuf->memsz; do { /* align down start */ temp_start = temp_start & (~(kbuf->buf_align - 1)); if (temp_start < start || temp_start < kbuf->buf_min) return 0; temp_end = temp_start + kbuf->memsz - 1; /* * Make sure this does not conflict with any of existing * segments */ if (kimage_is_destination_range(image, temp_start, temp_end)) { temp_start = temp_start - PAGE_SIZE; continue; } /* We found a suitable memory range */ break; } while (1); /* If we are here, we found a suitable memory range */ kbuf->mem = temp_start; /* Success, stop navigating through remaining System RAM ranges */ return 1; } static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end, struct kexec_buf *kbuf) { struct kimage *image = kbuf->image; unsigned long temp_start, temp_end; temp_start = max(start, kbuf->buf_min); do { temp_start = ALIGN(temp_start, kbuf->buf_align); temp_end = temp_start + kbuf->memsz - 1; if (temp_end > end || temp_end > kbuf->buf_max) return 0; /* * Make sure this does not conflict with any of existing * segments */ if (kimage_is_destination_range(image, temp_start, temp_end)) { temp_start = temp_start + PAGE_SIZE; continue; } /* We found a suitable memory range */ break; } while (1); /* If we are here, we found a suitable memory range */ kbuf->mem = temp_start; /* Success, stop navigating through remaining System RAM ranges */ return 1; } static int locate_mem_hole_callback(u64 start, u64 end, void *arg) { struct kexec_buf *kbuf = (struct kexec_buf *)arg; unsigned long sz = end - start + 1; /* Returning 0 will take to next memory range */ if (sz < kbuf->memsz) return 0; if (end < kbuf->buf_min || start > kbuf->buf_max) return 0; /* * Allocate memory top down with-in ram range. Otherwise bottom up * allocation. */ if (kbuf->top_down) return locate_mem_hole_top_down(start, end, kbuf); return locate_mem_hole_bottom_up(start, end, kbuf); } /** * arch_kexec_walk_mem - call func(data) on free memory regions * @kbuf: Context info for the search. Also passed to @func. * @func: Function to call for each memory region. * * Return: The memory walk will stop when func returns a non-zero value * and that value will be returned. If all free regions are visited without * func returning non-zero, then zero will be returned. */ int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf, int (*func)(u64, u64, void *)) { if (kbuf->image->type == KEXEC_TYPE_CRASH) return walk_iomem_res_desc(crashk_res.desc, IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY, crashk_res.start, crashk_res.end, kbuf, func); else return walk_system_ram_res(0, ULONG_MAX, kbuf, func); } /** * kexec_locate_mem_hole - find free memory for the purgatory or the next kernel * @kbuf: Parameters for the memory search. * * On success, kbuf->mem will have the start address of the memory region found. * * Return: 0 on success, negative errno on error. */ int kexec_locate_mem_hole(struct kexec_buf *kbuf) { int ret; ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback); return ret == 1 ? 0 : -EADDRNOTAVAIL; } /** * kexec_add_buffer - place a buffer in a kexec segment * @kbuf: Buffer contents and memory parameters. * * This function assumes that kexec_mutex is held. * On successful return, @kbuf->mem will have the physical address of * the buffer in memory. * * Return: 0 on success, negative errno on error. */ int kexec_add_buffer(struct kexec_buf *kbuf) { struct kexec_segment *ksegment; int ret; /* Currently adding segment this way is allowed only in file mode */ if (!kbuf->image->file_mode) return -EINVAL; if (kbuf->image->nr_segments >= KEXEC_SEGMENT_MAX) return -EINVAL; /* * Make sure we are not trying to add buffer after allocating * control pages. All segments need to be placed first before * any control pages are allocated. As control page allocation * logic goes through list of segments to make sure there are * no destination overlaps. */ if (!list_empty(&kbuf->image->control_pages)) { WARN_ON(1); return -EINVAL; } /* Ensure minimum alignment needed for segments. */ kbuf->memsz = ALIGN(kbuf->memsz, PAGE_SIZE); kbuf->buf_align = max(kbuf->buf_align, PAGE_SIZE); /* Walk the RAM ranges and allocate a suitable range for the buffer */ ret = kexec_locate_mem_hole(kbuf); if (ret) return ret; /* Found a suitable memory range */ ksegment = &kbuf->image->segment[kbuf->image->nr_segments]; ksegment->kbuf = kbuf->buffer; ksegment->bufsz = kbuf->bufsz; ksegment->mem = kbuf->mem; ksegment->memsz = kbuf->memsz; kbuf->image->nr_segments++; return 0; } /* Calculate and store the digest of segments */ static int kexec_calculate_store_digests(struct kimage *image) { struct crypto_shash *tfm; struct shash_desc *desc; int ret = 0, i, j, zero_buf_sz, sha_region_sz; size_t desc_size, nullsz; char *digest; void *zero_buf; struct kexec_sha_region *sha_regions; struct purgatory_info *pi = &image->purgatory_info; zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT); zero_buf_sz = PAGE_SIZE; tfm = crypto_alloc_shash("sha256", 0, 0); if (IS_ERR(tfm)) { ret = PTR_ERR(tfm); goto out; } desc_size = crypto_shash_descsize(tfm) + sizeof(*desc); desc = kzalloc(desc_size, GFP_KERNEL); if (!desc) { ret = -ENOMEM; goto out_free_tfm; } sha_region_sz = KEXEC_SEGMENT_MAX * sizeof(struct kexec_sha_region); sha_regions = vzalloc(sha_region_sz); if (!sha_regions) goto out_free_desc; desc->tfm = tfm; desc->flags = 0; ret = crypto_shash_init(desc); if (ret < 0) goto out_free_sha_regions; digest = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL); if (!digest) { ret = -ENOMEM; goto out_free_sha_regions; } for (j = i = 0; i < image->nr_segments; i++) { struct kexec_segment *ksegment; ksegment = &image->segment[i]; /* * Skip purgatory as it will be modified once we put digest * info in purgatory. */ if (ksegment->kbuf == pi->purgatory_buf) continue; ret = crypto_shash_update(desc, ksegment->kbuf, ksegment->bufsz); if (ret) break; /* * Assume rest of the buffer is filled with zero and * update digest accordingly. */ nullsz = ksegment->memsz - ksegment->bufsz; while (nullsz) { unsigned long bytes = nullsz; if (bytes > zero_buf_sz) bytes = zero_buf_sz; ret = crypto_shash_update(desc, zero_buf, bytes); if (ret) break; nullsz -= bytes; } if (ret) break; sha_regions[j].start = ksegment->mem; sha_regions[j].len = ksegment->memsz; j++; } if (!ret) { ret = crypto_shash_final(desc, digest); if (ret) goto out_free_digest; ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha_regions", sha_regions, sha_region_sz, 0); if (ret) goto out_free_digest; ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha256_digest", digest, SHA256_DIGEST_SIZE, 0); if (ret) goto out_free_digest; } out_free_digest: kfree(digest); out_free_sha_regions: vfree(sha_regions); out_free_desc: kfree(desc); out_free_tfm: kfree(tfm); out: return ret; } /* Actually load purgatory. Lot of code taken from kexec-tools */ static int __kexec_load_purgatory(struct kimage *image, unsigned long min, unsigned long max, int top_down) { struct purgatory_info *pi = &image->purgatory_info; unsigned long align, bss_align, bss_sz, bss_pad; unsigned long entry, load_addr, curr_load_addr, bss_addr, offset; unsigned char *buf_addr, *src; int i, ret = 0, entry_sidx = -1; const Elf_Shdr *sechdrs_c; Elf_Shdr *sechdrs = NULL; struct kexec_buf kbuf = { .image = image, .bufsz = 0, .buf_align = 1, .buf_min = min, .buf_max = max, .top_down = top_down }; /* * sechdrs_c points to section headers in purgatory and are read * only. No modifications allowed. */ sechdrs_c = (void *)pi->ehdr + pi->ehdr->e_shoff; /* * We can not modify sechdrs_c[] and its fields. It is read only. * Copy it over to a local copy where one can store some temporary * data and free it at the end. We need to modify ->sh_addr and * ->sh_offset fields to keep track of permanent and temporary * locations of sections. */ sechdrs = vzalloc(pi->ehdr->e_shnum * sizeof(Elf_Shdr)); if (!sechdrs) return -ENOMEM; memcpy(sechdrs, sechdrs_c, pi->ehdr->e_shnum * sizeof(Elf_Shdr)); /* * We seem to have multiple copies of sections. First copy is which * is embedded in kernel in read only section. Some of these sections * will be copied to a temporary buffer and relocated. And these * sections will finally be copied to their final destination at * segment load time. * * Use ->sh_offset to reflect section address in memory. It will * point to original read only copy if section is not allocatable. * Otherwise it will point to temporary copy which will be relocated. * * Use ->sh_addr to contain final address of the section where it * will go during execution time. */ for (i = 0; i < pi->ehdr->e_shnum; i++) { if (sechdrs[i].sh_type == SHT_NOBITS) continue; sechdrs[i].sh_offset = (unsigned long)pi->ehdr + sechdrs[i].sh_offset; } /* * Identify entry point section and make entry relative to section * start. */ entry = pi->ehdr->e_entry; for (i = 0; i < pi->ehdr->e_shnum; i++) { if (!(sechdrs[i].sh_flags & SHF_ALLOC)) continue; if (!(sechdrs[i].sh_flags & SHF_EXECINSTR)) continue; /* Make entry section relative */ if (sechdrs[i].sh_addr <= pi->ehdr->e_entry && ((sechdrs[i].sh_addr + sechdrs[i].sh_size) > pi->ehdr->e_entry)) { entry_sidx = i; entry -= sechdrs[i].sh_addr; break; } } /* Determine how much memory is needed to load relocatable object. */ bss_align = 1; bss_sz = 0; for (i = 0; i < pi->ehdr->e_shnum; i++) { if (!(sechdrs[i].sh_flags & SHF_ALLOC)) continue; align = sechdrs[i].sh_addralign; if (sechdrs[i].sh_type != SHT_NOBITS) { if (kbuf.buf_align < align) kbuf.buf_align = align; kbuf.bufsz = ALIGN(kbuf.bufsz, align); kbuf.bufsz += sechdrs[i].sh_size; } else { /* bss section */ if (bss_align < align) bss_align = align; bss_sz = ALIGN(bss_sz, align); bss_sz += sechdrs[i].sh_size; } } /* Determine the bss padding required to align bss properly */ bss_pad = 0; if (kbuf.bufsz & (bss_align - 1)) bss_pad = bss_align - (kbuf.bufsz & (bss_align - 1)); kbuf.memsz = kbuf.bufsz + bss_pad + bss_sz; /* Allocate buffer for purgatory */ kbuf.buffer = vzalloc(kbuf.bufsz); if (!kbuf.buffer) { ret = -ENOMEM; goto out; } if (kbuf.buf_align < bss_align) kbuf.buf_align = bss_align; /* Add buffer to segment list */ ret = kexec_add_buffer(&kbuf); if (ret) goto out; pi->purgatory_load_addr = kbuf.mem; /* Load SHF_ALLOC sections */ buf_addr = kbuf.buffer; load_addr = curr_load_addr = pi->purgatory_load_addr; bss_addr = load_addr + kbuf.bufsz + bss_pad; for (i = 0; i < pi->ehdr->e_shnum; i++) { if (!(sechdrs[i].sh_flags & SHF_ALLOC)) continue; align = sechdrs[i].sh_addralign; if (sechdrs[i].sh_type != SHT_NOBITS) { curr_load_addr = ALIGN(curr_load_addr, align); offset = curr_load_addr - load_addr; /* We already modifed ->sh_offset to keep src addr */ src = (char *) sechdrs[i].sh_offset; memcpy(buf_addr + offset, src, sechdrs[i].sh_size); /* Store load address and source address of section */ sechdrs[i].sh_addr = curr_load_addr; /* * This section got copied to temporary buffer. Update * ->sh_offset accordingly. */ sechdrs[i].sh_offset = (unsigned long)(buf_addr + offset); /* Advance to the next address */ curr_load_addr += sechdrs[i].sh_size; } else { bss_addr = ALIGN(bss_addr, align); sechdrs[i].sh_addr = bss_addr; bss_addr += sechdrs[i].sh_size; } } /* Update entry point based on load address of text section */ if (entry_sidx >= 0) entry += sechdrs[entry_sidx].sh_addr; /* Make kernel jump to purgatory after shutdown */ image->start = entry; /* Used later to get/set symbol values */ pi->sechdrs = sechdrs; /* * Used later to identify which section is purgatory and skip it * from checksumming. */ pi->purgatory_buf = kbuf.buffer; return ret; out: vfree(sechdrs); vfree(kbuf.buffer); return ret; } static int kexec_apply_relocations(struct kimage *image) { int i, ret; struct purgatory_info *pi = &image->purgatory_info; Elf_Shdr *sechdrs = pi->sechdrs; /* Apply relocations */ for (i = 0; i < pi->ehdr->e_shnum; i++) { Elf_Shdr *section, *symtab; if (sechdrs[i].sh_type != SHT_RELA && sechdrs[i].sh_type != SHT_REL) continue; /* * For section of type SHT_RELA/SHT_REL, * ->sh_link contains section header index of associated * symbol table. And ->sh_info contains section header * index of section to which relocations apply. */ if (sechdrs[i].sh_info >= pi->ehdr->e_shnum || sechdrs[i].sh_link >= pi->ehdr->e_shnum) return -ENOEXEC; section = &sechdrs[sechdrs[i].sh_info]; symtab = &sechdrs[sechdrs[i].sh_link]; if (!(section->sh_flags & SHF_ALLOC)) continue; /* * symtab->sh_link contain section header index of associated * string table. */ if (symtab->sh_link >= pi->ehdr->e_shnum) /* Invalid section number? */ continue; /* * Respective architecture needs to provide support for applying * relocations of type SHT_RELA/SHT_REL. */ if (sechdrs[i].sh_type == SHT_RELA) ret = arch_kexec_apply_relocations_add(pi->ehdr, sechdrs, i); else if (sechdrs[i].sh_type == SHT_REL) ret = arch_kexec_apply_relocations(pi->ehdr, sechdrs, i); if (ret) return ret; } return 0; } /* Load relocatable purgatory object and relocate it appropriately */ int kexec_load_purgatory(struct kimage *image, unsigned long min, unsigned long max, int top_down, unsigned long *load_addr) { struct purgatory_info *pi = &image->purgatory_info; int ret; if (kexec_purgatory_size <= 0) return -EINVAL; if (kexec_purgatory_size < sizeof(Elf_Ehdr)) return -ENOEXEC; pi->ehdr = (Elf_Ehdr *)kexec_purgatory; if (memcmp(pi->ehdr->e_ident, ELFMAG, SELFMAG) != 0 || pi->ehdr->e_type != ET_REL || !elf_check_arch(pi->ehdr) || pi->ehdr->e_shentsize != sizeof(Elf_Shdr)) return -ENOEXEC; if (pi->ehdr->e_shoff >= kexec_purgatory_size || (pi->ehdr->e_shnum * sizeof(Elf_Shdr) > kexec_purgatory_size - pi->ehdr->e_shoff)) return -ENOEXEC; ret = __kexec_load_purgatory(image, min, max, top_down); if (ret) return ret; ret = kexec_apply_relocations(image); if (ret) goto out; *load_addr = pi->purgatory_load_addr; return 0; out: vfree(pi->sechdrs); pi->sechdrs = NULL; vfree(pi->purgatory_buf); pi->purgatory_buf = NULL; return ret; } static Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi, const char *name) { Elf_Sym *syms; Elf_Shdr *sechdrs; Elf_Ehdr *ehdr; int i, k; const char *strtab; if (!pi->sechdrs || !pi->ehdr) return NULL; sechdrs = pi->sechdrs; ehdr = pi->ehdr; for (i = 0; i < ehdr->e_shnum; i++) { if (sechdrs[i].sh_type != SHT_SYMTAB) continue; if (sechdrs[i].sh_link >= ehdr->e_shnum) /* Invalid strtab section number */ continue; strtab = (char *)sechdrs[sechdrs[i].sh_link].sh_offset; syms = (Elf_Sym *)sechdrs[i].sh_offset; /* Go through symbols for a match */ for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) { if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL) continue; if (strcmp(strtab + syms[k].st_name, name) != 0) continue; if (syms[k].st_shndx == SHN_UNDEF || syms[k].st_shndx >= ehdr->e_shnum) { pr_debug("Symbol: %s has bad section index %d.\n", name, syms[k].st_shndx); return NULL; } /* Found the symbol we are looking for */ return &syms[k]; } } return NULL; } void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name) { struct purgatory_info *pi = &image->purgatory_info; Elf_Sym *sym; Elf_Shdr *sechdr; sym = kexec_purgatory_find_symbol(pi, name); if (!sym) return ERR_PTR(-EINVAL); sechdr = &pi->sechdrs[sym->st_shndx]; /* * Returns the address where symbol will finally be loaded after * kexec_load_segment() */ return (void *)(sechdr->sh_addr + sym->st_value); } /* * Get or set value of a symbol. If "get_value" is true, symbol value is * returned in buf otherwise symbol value is set based on value in buf. */ int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name, void *buf, unsigned int size, bool get_value) { Elf_Sym *sym; Elf_Shdr *sechdrs; struct purgatory_info *pi = &image->purgatory_info; char *sym_buf; sym = kexec_purgatory_find_symbol(pi, name); if (!sym) return -EINVAL; if (sym->st_size != size) { pr_err("symbol %s size mismatch: expected %lu actual %u\n", name, (unsigned long)sym->st_size, size); return -EINVAL; } sechdrs = pi->sechdrs; if (sechdrs[sym->st_shndx].sh_type == SHT_NOBITS) { pr_err("symbol %s is in a bss section. Cannot %s\n", name, get_value ? "get" : "set"); return -EINVAL; } sym_buf = (unsigned char *)sechdrs[sym->st_shndx].sh_offset + sym->st_value; if (get_value) memcpy((void *)buf, sym_buf, size); else memcpy((void *)sym_buf, buf, size); return 0; }