diff options
Diffstat (limited to 'kernel/module/decompress.c')
| -rw-r--r-- | kernel/module/decompress.c | 368 |
1 files changed, 368 insertions, 0 deletions
diff --git a/kernel/module/decompress.c b/kernel/module/decompress.c new file mode 100644 index 0000000000..474e68f0f0 --- /dev/null +++ b/kernel/module/decompress.c @@ -0,0 +1,368 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright 2021 Google LLC. + */ + +#include <linux/init.h> +#include <linux/highmem.h> +#include <linux/kobject.h> +#include <linux/mm.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/sysfs.h> +#include <linux/vmalloc.h> + +#include "internal.h" + +static int module_extend_max_pages(struct load_info *info, unsigned int extent) +{ + struct page **new_pages; + + new_pages = kvmalloc_array(info->max_pages + extent, + sizeof(info->pages), GFP_KERNEL); + if (!new_pages) + return -ENOMEM; + + memcpy(new_pages, info->pages, info->max_pages * sizeof(info->pages)); + kvfree(info->pages); + info->pages = new_pages; + info->max_pages += extent; + + return 0; +} + +static struct page *module_get_next_page(struct load_info *info) +{ + struct page *page; + int error; + + if (info->max_pages == info->used_pages) { + error = module_extend_max_pages(info, info->used_pages); + if (error) + return ERR_PTR(error); + } + + page = alloc_page(GFP_KERNEL | __GFP_HIGHMEM); + if (!page) + return ERR_PTR(-ENOMEM); + + info->pages[info->used_pages++] = page; + return page; +} + +#if defined(CONFIG_MODULE_COMPRESS_GZIP) +#include <linux/zlib.h> +#define MODULE_COMPRESSION gzip +#define MODULE_DECOMPRESS_FN module_gzip_decompress + +/* + * Calculate length of the header which consists of signature, header + * flags, time stamp and operating system ID (10 bytes total), plus + * an optional filename. + */ +static size_t module_gzip_header_len(const u8 *buf, size_t size) +{ + const u8 signature[] = { 0x1f, 0x8b, 0x08 }; + size_t len = 10; + + if (size < len || memcmp(buf, signature, sizeof(signature))) + return 0; + + if (buf[3] & 0x08) { + do { + /* + * If we can't find the end of the file name we must + * be dealing with a corrupted file. + */ + if (len == size) + return 0; + } while (buf[len++] != '\0'); + } + + return len; +} + +static ssize_t module_gzip_decompress(struct load_info *info, + const void *buf, size_t size) +{ + struct z_stream_s s = { 0 }; + size_t new_size = 0; + size_t gzip_hdr_len; + ssize_t retval; + int rc; + + gzip_hdr_len = module_gzip_header_len(buf, size); + if (!gzip_hdr_len) { + pr_err("not a gzip compressed module\n"); + return -EINVAL; + } + + s.next_in = buf + gzip_hdr_len; + s.avail_in = size - gzip_hdr_len; + + s.workspace = kvmalloc(zlib_inflate_workspacesize(), GFP_KERNEL); + if (!s.workspace) + return -ENOMEM; + + rc = zlib_inflateInit2(&s, -MAX_WBITS); + if (rc != Z_OK) { + pr_err("failed to initialize decompressor: %d\n", rc); + retval = -EINVAL; + goto out; + } + + do { + struct page *page = module_get_next_page(info); + + if (IS_ERR(page)) { + retval = PTR_ERR(page); + goto out_inflate_end; + } + + s.next_out = kmap_local_page(page); + s.avail_out = PAGE_SIZE; + rc = zlib_inflate(&s, 0); + kunmap_local(s.next_out); + + new_size += PAGE_SIZE - s.avail_out; + } while (rc == Z_OK); + + if (rc != Z_STREAM_END) { + pr_err("decompression failed with status %d\n", rc); + retval = -EINVAL; + goto out_inflate_end; + } + + retval = new_size; + +out_inflate_end: + zlib_inflateEnd(&s); +out: + kvfree(s.workspace); + return retval; +} +#elif defined(CONFIG_MODULE_COMPRESS_XZ) +#include <linux/xz.h> +#define MODULE_COMPRESSION xz +#define MODULE_DECOMPRESS_FN module_xz_decompress + +static ssize_t module_xz_decompress(struct load_info *info, + const void *buf, size_t size) +{ + static const u8 signature[] = { 0xfd, '7', 'z', 'X', 'Z', 0 }; + struct xz_dec *xz_dec; + struct xz_buf xz_buf; + enum xz_ret xz_ret; + size_t new_size = 0; + ssize_t retval; + + if (size < sizeof(signature) || + memcmp(buf, signature, sizeof(signature))) { + pr_err("not an xz compressed module\n"); + return -EINVAL; + } + + xz_dec = xz_dec_init(XZ_DYNALLOC, (u32)-1); + if (!xz_dec) + return -ENOMEM; + + xz_buf.in_size = size; + xz_buf.in = buf; + xz_buf.in_pos = 0; + + do { + struct page *page = module_get_next_page(info); + + if (IS_ERR(page)) { + retval = PTR_ERR(page); + goto out; + } + + xz_buf.out = kmap_local_page(page); + xz_buf.out_pos = 0; + xz_buf.out_size = PAGE_SIZE; + xz_ret = xz_dec_run(xz_dec, &xz_buf); + kunmap_local(xz_buf.out); + + new_size += xz_buf.out_pos; + } while (xz_buf.out_pos == PAGE_SIZE && xz_ret == XZ_OK); + + if (xz_ret != XZ_STREAM_END) { + pr_err("decompression failed with status %d\n", xz_ret); + retval = -EINVAL; + goto out; + } + + retval = new_size; + + out: + xz_dec_end(xz_dec); + return retval; +} +#elif defined(CONFIG_MODULE_COMPRESS_ZSTD) +#include <linux/zstd.h> +#define MODULE_COMPRESSION zstd +#define MODULE_DECOMPRESS_FN module_zstd_decompress + +static ssize_t module_zstd_decompress(struct load_info *info, + const void *buf, size_t size) +{ + static const u8 signature[] = { 0x28, 0xb5, 0x2f, 0xfd }; + ZSTD_outBuffer zstd_dec; + ZSTD_inBuffer zstd_buf; + zstd_frame_header header; + size_t wksp_size; + void *wksp = NULL; + ZSTD_DStream *dstream; + size_t ret; + size_t new_size = 0; + int retval; + + if (size < sizeof(signature) || + memcmp(buf, signature, sizeof(signature))) { + pr_err("not a zstd compressed module\n"); + return -EINVAL; + } + + zstd_buf.src = buf; + zstd_buf.pos = 0; + zstd_buf.size = size; + + ret = zstd_get_frame_header(&header, zstd_buf.src, zstd_buf.size); + if (ret != 0) { + pr_err("ZSTD-compressed data has an incomplete frame header\n"); + retval = -EINVAL; + goto out; + } + if (header.windowSize > (1 << ZSTD_WINDOWLOG_MAX)) { + pr_err("ZSTD-compressed data has too large a window size\n"); + retval = -EINVAL; + goto out; + } + + wksp_size = zstd_dstream_workspace_bound(header.windowSize); + wksp = kvmalloc(wksp_size, GFP_KERNEL); + if (!wksp) { + retval = -ENOMEM; + goto out; + } + + dstream = zstd_init_dstream(header.windowSize, wksp, wksp_size); + if (!dstream) { + pr_err("Can't initialize ZSTD stream\n"); + retval = -ENOMEM; + goto out; + } + + do { + struct page *page = module_get_next_page(info); + + if (IS_ERR(page)) { + retval = PTR_ERR(page); + goto out; + } + + zstd_dec.dst = kmap_local_page(page); + zstd_dec.pos = 0; + zstd_dec.size = PAGE_SIZE; + + ret = zstd_decompress_stream(dstream, &zstd_dec, &zstd_buf); + kunmap_local(zstd_dec.dst); + retval = zstd_get_error_code(ret); + if (retval) + break; + + new_size += zstd_dec.pos; + } while (zstd_dec.pos == PAGE_SIZE && ret != 0); + + if (retval) { + pr_err("ZSTD-decompression failed with status %d\n", retval); + retval = -EINVAL; + goto out; + } + + retval = new_size; + + out: + kvfree(wksp); + return retval; +} +#else +#error "Unexpected configuration for CONFIG_MODULE_DECOMPRESS" +#endif + +int module_decompress(struct load_info *info, const void *buf, size_t size) +{ + unsigned int n_pages; + ssize_t data_size; + int error; + +#if defined(CONFIG_MODULE_STATS) + info->compressed_len = size; +#endif + + /* + * Start with number of pages twice as big as needed for + * compressed data. + */ + n_pages = DIV_ROUND_UP(size, PAGE_SIZE) * 2; + error = module_extend_max_pages(info, n_pages); + + data_size = MODULE_DECOMPRESS_FN(info, buf, size); + if (data_size < 0) { + error = data_size; + goto err; + } + + info->hdr = vmap(info->pages, info->used_pages, VM_MAP, PAGE_KERNEL); + if (!info->hdr) { + error = -ENOMEM; + goto err; + } + + info->len = data_size; + return 0; + +err: + module_decompress_cleanup(info); + return error; +} + +void module_decompress_cleanup(struct load_info *info) +{ + int i; + + if (info->hdr) + vunmap(info->hdr); + + for (i = 0; i < info->used_pages; i++) + __free_page(info->pages[i]); + + kvfree(info->pages); + + info->pages = NULL; + info->max_pages = info->used_pages = 0; +} + +#ifdef CONFIG_SYSFS +static ssize_t compression_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sysfs_emit(buf, __stringify(MODULE_COMPRESSION) "\n"); +} + +static struct kobj_attribute module_compression_attr = __ATTR_RO(compression); + +static int __init module_decompress_sysfs_init(void) +{ + int error; + + error = sysfs_create_file(&module_kset->kobj, + &module_compression_attr.attr); + if (error) + pr_warn("Failed to create 'compression' attribute"); + + return 0; +} +late_initcall(module_decompress_sysfs_init); +#endif |