diff options
Diffstat (limited to '')
| -rw-r--r-- | kernel/kexec_file.c | 1159 |
1 files changed, 1159 insertions, 0 deletions
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c new file mode 100644 index 0000000000..f9a419cd22 --- /dev/null +++ b/kernel/kexec_file.c @@ -0,0 +1,1159 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * kexec: kexec_file_load system call + * + * Copyright (C) 2014 Red Hat Inc. + * Authors: + * Vivek Goyal <vgoyal@redhat.com> + */ + +#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/memblock.h> +#include <linux/mutex.h> +#include <linux/list.h> +#include <linux/fs.h> +#include <linux/ima.h> +#include <crypto/hash.h> +#include <crypto/sha2.h> +#include <linux/elf.h> +#include <linux/elfcore.h> +#include <linux/kernel.h> +#include <linux/kernel_read_file.h> +#include <linux/syscalls.h> +#include <linux/vmalloc.h> +#include "kexec_internal.h" + +#ifdef CONFIG_KEXEC_SIG +static bool sig_enforce = IS_ENABLED(CONFIG_KEXEC_SIG_FORCE); + +void set_kexec_sig_enforced(void) +{ + sig_enforce = true; +} +#endif + +static int kexec_calculate_store_digests(struct kimage *image); + +/* Maximum size in bytes for kernel/initrd files. */ +#define KEXEC_FILE_SIZE_MAX min_t(s64, 4LL << 30, SSIZE_MAX) + +/* + * Currently this is the only default function that is exported as some + * architectures need it to do additional handlings. + * In the future, other default functions may be exported too if required. + */ +int kexec_image_probe_default(struct kimage *image, void *buf, + unsigned long buf_len) +{ + const struct kexec_file_ops * const *fops; + int ret = -ENOEXEC; + + for (fops = &kexec_file_loaders[0]; *fops && (*fops)->probe; ++fops) { + ret = (*fops)->probe(buf, buf_len); + if (!ret) { + image->fops = *fops; + return ret; + } + } + + return ret; +} + +static void *kexec_image_load_default(struct kimage *image) +{ + if (!image->fops || !image->fops->load) + return ERR_PTR(-ENOEXEC); + + return image->fops->load(image, image->kernel_buf, + image->kernel_buf_len, image->initrd_buf, + image->initrd_buf_len, image->cmdline_buf, + image->cmdline_buf_len); +} + +int kexec_image_post_load_cleanup_default(struct kimage *image) +{ + if (!image->fops || !image->fops->cleanup) + return 0; + + return image->fops->cleanup(image->image_loader_data); +} + +/* + * 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; + +#ifdef CONFIG_IMA_KEXEC + vfree(image->ima_buffer); + image->ima_buffer = NULL; +#endif /* CONFIG_IMA_KEXEC */ + + /* 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; +} + +#ifdef CONFIG_KEXEC_SIG +#ifdef CONFIG_SIGNED_PE_FILE_VERIFICATION +int kexec_kernel_verify_pe_sig(const char *kernel, unsigned long kernel_len) +{ + int ret; + + ret = verify_pefile_signature(kernel, kernel_len, + VERIFY_USE_SECONDARY_KEYRING, + VERIFYING_KEXEC_PE_SIGNATURE); + if (ret == -ENOKEY && IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING)) { + ret = verify_pefile_signature(kernel, kernel_len, + VERIFY_USE_PLATFORM_KEYRING, + VERIFYING_KEXEC_PE_SIGNATURE); + } + return ret; +} +#endif + +static int kexec_image_verify_sig(struct kimage *image, void *buf, + unsigned long buf_len) +{ + if (!image->fops || !image->fops->verify_sig) { + pr_debug("kernel loader does not support signature verification.\n"); + return -EKEYREJECTED; + } + + return image->fops->verify_sig(buf, buf_len); +} + +static int +kimage_validate_signature(struct kimage *image) +{ + int ret; + + ret = kexec_image_verify_sig(image, image->kernel_buf, + image->kernel_buf_len); + if (ret) { + + if (sig_enforce) { + pr_notice("Enforced kernel signature verification failed (%d).\n", ret); + return ret; + } + + /* + * If IMA is guaranteed to appraise a signature on the kexec + * image, permit it even if the kernel is otherwise locked + * down. + */ + if (!ima_appraise_signature(READING_KEXEC_IMAGE) && + security_locked_down(LOCKDOWN_KEXEC)) + return -EPERM; + + pr_debug("kernel signature verification failed (%d).\n", ret); + } + + return 0; +} +#endif + +/* + * 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) +{ + ssize_t ret; + void *ldata; + + ret = kernel_read_file_from_fd(kernel_fd, 0, &image->kernel_buf, + KEXEC_FILE_SIZE_MAX, NULL, + READING_KEXEC_IMAGE); + if (ret < 0) + return ret; + image->kernel_buf_len = ret; + + /* 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_SIG + ret = kimage_validate_signature(image); + + if (ret) + goto out; +#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, 0, &image->initrd_buf, + KEXEC_FILE_SIZE_MAX, NULL, + READING_KEXEC_INITRAMFS); + if (ret < 0) + goto out; + image->initrd_buf_len = ret; + ret = 0; + } + + 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; + } + + ima_kexec_cmdline(kernel_fd, image->cmdline_buf, + image->cmdline_buf_len - 1); + } + + /* IMA needs to pass the measurement list to the next kernel. */ + ima_add_kexec_buffer(image); + + /* Call image load handler */ + ldata = kexec_image_load_default(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 image_type = (flags & KEXEC_FILE_ON_CRASH) ? + KEXEC_TYPE_CRASH : KEXEC_TYPE_DEFAULT; + struct kimage **dest_image, *image; + int ret = 0, i; + + /* We only trust the superuser with rebooting the system. */ + if (!kexec_load_permitted(image_type)) + return -EPERM; + + /* Make sure we have a legal set of flags */ + if (flags != (flags & KEXEC_FILE_FLAGS)) + return -EINVAL; + + image = NULL; + + if (!kexec_trylock()) + return -EBUSY; + + if (image_type == KEXEC_TYPE_CRASH) { + dest_image = &kexec_crash_image; + if (kexec_crash_image) + arch_kexec_unprotect_crashkres(); + } else { + dest_image = &kexec_image; + } + + 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); + + ret = machine_kexec_post_load(image); + if (ret) + goto out; + + /* + * 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(); + + kexec_unlock(); + 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(struct resource *res, void *arg) +{ + struct kexec_buf *kbuf = (struct kexec_buf *)arg; + u64 start = res->start, end = res->end; + unsigned long sz = end - start + 1; + + /* Returning 0 will take to next memory range */ + + /* Don't use memory that will be detected and handled by a driver. */ + if (res->flags & IORESOURCE_SYSRAM_DRIVER_MANAGED) + return 0; + + 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); +} + +#ifdef CONFIG_ARCH_KEEP_MEMBLOCK +static int kexec_walk_memblock(struct kexec_buf *kbuf, + int (*func)(struct resource *, void *)) +{ + int ret = 0; + u64 i; + phys_addr_t mstart, mend; + struct resource res = { }; + + if (kbuf->image->type == KEXEC_TYPE_CRASH) + return func(&crashk_res, kbuf); + + /* + * Using MEMBLOCK_NONE will properly skip MEMBLOCK_DRIVER_MANAGED. See + * IORESOURCE_SYSRAM_DRIVER_MANAGED handling in + * locate_mem_hole_callback(). + */ + if (kbuf->top_down) { + for_each_free_mem_range_reverse(i, NUMA_NO_NODE, MEMBLOCK_NONE, + &mstart, &mend, NULL) { + /* + * In memblock, end points to the first byte after the + * range while in kexec, end points to the last byte + * in the range. + */ + res.start = mstart; + res.end = mend - 1; + ret = func(&res, kbuf); + if (ret) + break; + } + } else { + for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE, + &mstart, &mend, NULL) { + /* + * In memblock, end points to the first byte after the + * range while in kexec, end points to the last byte + * in the range. + */ + res.start = mstart; + res.end = mend - 1; + ret = func(&res, kbuf); + if (ret) + break; + } + } + + return ret; +} +#else +static int kexec_walk_memblock(struct kexec_buf *kbuf, + int (*func)(struct resource *, void *)) +{ + return 0; +} +#endif + +/** + * kexec_walk_resources - 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. + */ +static int kexec_walk_resources(struct kexec_buf *kbuf, + int (*func)(struct resource *, 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; + + /* Arch knows where to place */ + if (kbuf->mem != KEXEC_BUF_MEM_UNKNOWN) + return 0; + + if (!IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)) + ret = kexec_walk_resources(kbuf, locate_mem_hole_callback); + else + ret = kexec_walk_memblock(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_lock 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 = arch_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; + + if (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY)) + return 0; + + 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) { + ret = -ENOMEM; + goto out_free_desc; + } + + desc->tfm = tfm; + + 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; + +#ifdef CONFIG_CRASH_HOTPLUG + /* Exclude elfcorehdr segment to allow future changes via hotplug */ + if (j == image->elfcorehdr_index) + continue; +#endif + + 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; +} + +#ifdef CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY +/* + * kexec_purgatory_setup_kbuf - prepare buffer to load purgatory. + * @pi: Purgatory to be loaded. + * @kbuf: Buffer to setup. + * + * Allocates the memory needed for the buffer. Caller is responsible to free + * the memory after use. + * + * Return: 0 on success, negative errno on error. + */ +static int kexec_purgatory_setup_kbuf(struct purgatory_info *pi, + struct kexec_buf *kbuf) +{ + const Elf_Shdr *sechdrs; + unsigned long bss_align; + unsigned long bss_sz; + unsigned long align; + int i, ret; + + sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff; + kbuf->buf_align = bss_align = 1; + kbuf->bufsz = 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 { + if (bss_align < align) + bss_align = align; + bss_sz = ALIGN(bss_sz, align); + bss_sz += sechdrs[i].sh_size; + } + } + kbuf->bufsz = ALIGN(kbuf->bufsz, bss_align); + kbuf->memsz = kbuf->bufsz + bss_sz; + if (kbuf->buf_align < bss_align) + kbuf->buf_align = bss_align; + + kbuf->buffer = vzalloc(kbuf->bufsz); + if (!kbuf->buffer) + return -ENOMEM; + pi->purgatory_buf = kbuf->buffer; + + ret = kexec_add_buffer(kbuf); + if (ret) + goto out; + + return 0; +out: + vfree(pi->purgatory_buf); + pi->purgatory_buf = NULL; + return ret; +} + +/* + * kexec_purgatory_setup_sechdrs - prepares the pi->sechdrs buffer. + * @pi: Purgatory to be loaded. + * @kbuf: Buffer prepared to store purgatory. + * + * Allocates the memory needed for the buffer. Caller is responsible to free + * the memory after use. + * + * Return: 0 on success, negative errno on error. + */ +static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi, + struct kexec_buf *kbuf) +{ + unsigned long bss_addr; + unsigned long offset; + size_t sechdrs_size; + Elf_Shdr *sechdrs; + int i; + + /* + * The section headers in kexec_purgatory are read-only. In order to + * have them modifiable make a temporary copy. + */ + sechdrs_size = array_size(sizeof(Elf_Shdr), pi->ehdr->e_shnum); + sechdrs = vzalloc(sechdrs_size); + if (!sechdrs) + return -ENOMEM; + memcpy(sechdrs, (void *)pi->ehdr + pi->ehdr->e_shoff, sechdrs_size); + pi->sechdrs = sechdrs; + + offset = 0; + bss_addr = kbuf->mem + kbuf->bufsz; + kbuf->image->start = pi->ehdr->e_entry; + + for (i = 0; i < pi->ehdr->e_shnum; i++) { + unsigned long align; + void *src, *dst; + + if (!(sechdrs[i].sh_flags & SHF_ALLOC)) + continue; + + align = sechdrs[i].sh_addralign; + if (sechdrs[i].sh_type == SHT_NOBITS) { + bss_addr = ALIGN(bss_addr, align); + sechdrs[i].sh_addr = bss_addr; + bss_addr += sechdrs[i].sh_size; + continue; + } + + offset = ALIGN(offset, align); + + /* + * Check if the segment contains the entry point, if so, + * calculate the value of image->start based on it. + * If the compiler has produced more than one .text section + * (Eg: .text.hot), they are generally after the main .text + * section, and they shall not be used to calculate + * image->start. So do not re-calculate image->start if it + * is not set to the initial value, and warn the user so they + * have a chance to fix their purgatory's linker script. + */ + if (sechdrs[i].sh_flags & SHF_EXECINSTR && + pi->ehdr->e_entry >= sechdrs[i].sh_addr && + pi->ehdr->e_entry < (sechdrs[i].sh_addr + + sechdrs[i].sh_size) && + !WARN_ON(kbuf->image->start != pi->ehdr->e_entry)) { + kbuf->image->start -= sechdrs[i].sh_addr; + kbuf->image->start += kbuf->mem + offset; + } + + src = (void *)pi->ehdr + sechdrs[i].sh_offset; + dst = pi->purgatory_buf + offset; + memcpy(dst, src, sechdrs[i].sh_size); + + sechdrs[i].sh_addr = kbuf->mem + offset; + sechdrs[i].sh_offset = offset; + offset += sechdrs[i].sh_size; + } + + return 0; +} + +static int kexec_apply_relocations(struct kimage *image) +{ + int i, ret; + struct purgatory_info *pi = &image->purgatory_info; + const Elf_Shdr *sechdrs; + + sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff; + + for (i = 0; i < pi->ehdr->e_shnum; i++) { + const Elf_Shdr *relsec; + const Elf_Shdr *symtab; + Elf_Shdr *section; + + relsec = sechdrs + i; + + if (relsec->sh_type != SHT_RELA && + relsec->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 (relsec->sh_info >= pi->ehdr->e_shnum || + relsec->sh_link >= pi->ehdr->e_shnum) + return -ENOEXEC; + + section = pi->sechdrs + relsec->sh_info; + symtab = sechdrs + relsec->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 (relsec->sh_type == SHT_RELA) + ret = arch_kexec_apply_relocations_add(pi, section, + relsec, symtab); + else if (relsec->sh_type == SHT_REL) + ret = arch_kexec_apply_relocations(pi, section, + relsec, symtab); + if (ret) + return ret; + } + + return 0; +} + +/* + * kexec_load_purgatory - Load and relocate the purgatory object. + * @image: Image to add the purgatory to. + * @kbuf: Memory parameters to use. + * + * Allocates the memory needed for image->purgatory_info.sechdrs and + * image->purgatory_info.purgatory_buf/kbuf->buffer. Caller is responsible + * to free the memory after use. + * + * Return: 0 on success, negative errno on error. + */ +int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf) +{ + struct purgatory_info *pi = &image->purgatory_info; + int ret; + + if (kexec_purgatory_size <= 0) + return -EINVAL; + + pi->ehdr = (const Elf_Ehdr *)kexec_purgatory; + + ret = kexec_purgatory_setup_kbuf(pi, kbuf); + if (ret) + return ret; + + ret = kexec_purgatory_setup_sechdrs(pi, kbuf); + if (ret) + goto out_free_kbuf; + + ret = kexec_apply_relocations(image); + if (ret) + goto out; + + return 0; +out: + vfree(pi->sechdrs); + pi->sechdrs = NULL; +out_free_kbuf: + vfree(pi->purgatory_buf); + pi->purgatory_buf = NULL; + return ret; +} + +/* + * kexec_purgatory_find_symbol - find a symbol in the purgatory + * @pi: Purgatory to search in. + * @name: Name of the symbol. + * + * Return: pointer to symbol in read-only symtab on success, NULL on error. + */ +static const Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi, + const char *name) +{ + const Elf_Shdr *sechdrs; + const Elf_Ehdr *ehdr; + const Elf_Sym *syms; + const char *strtab; + int i, k; + + if (!pi->ehdr) + return NULL; + + ehdr = pi->ehdr; + sechdrs = (void *)ehdr + ehdr->e_shoff; + + 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 = (void *)ehdr + sechdrs[sechdrs[i].sh_link].sh_offset; + syms = (void *)ehdr + 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; + const 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) +{ + struct purgatory_info *pi = &image->purgatory_info; + const Elf_Sym *sym; + Elf_Shdr *sec; + 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; + } + + sec = pi->sechdrs + sym->st_shndx; + + if (sec->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 = (char *)pi->purgatory_buf + sec->sh_offset + sym->st_value; + + if (get_value) + memcpy((void *)buf, sym_buf, size); + else + memcpy((void *)sym_buf, buf, size); + + return 0; +} +#endif /* CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY */ |