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1// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)2/*3 * Routines for dealing with .zip archives.4 *5 * Copyright (c) Meta Platforms, Inc. and affiliates.6 */7 8#include <errno.h>9#include <fcntl.h>10#include <stdint.h>11#include <stdlib.h>12#include <string.h>13#include <sys/mman.h>14#include <unistd.h>15 16#include "libbpf_internal.h"17#include "zip.h"18 19#pragma GCC diagnostic push20#pragma GCC diagnostic ignored "-Wpacked"21#pragma GCC diagnostic ignored "-Wattributes"22 23/* Specification of ZIP file format can be found here:24 * https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT25 * For a high level overview of the structure of a ZIP file see26 * sections 4.3.1 - 4.3.6.27 *28 * Data structures appearing in ZIP files do not contain any29 * padding and they might be misaligned. To allow us to safely30 * operate on pointers to such structures and their members, we31 * declare the types as packed.32 */33 34#define END_OF_CD_RECORD_MAGIC 0x06054b5035 36/* See section 4.3.16 of the spec. */37struct end_of_cd_record {38 /* Magic value equal to END_OF_CD_RECORD_MAGIC */39 __u32 magic;40 41 /* Number of the file containing this structure or 0xFFFF if ZIP64 archive.42 * Zip archive might span multiple files (disks).43 */44 __u16 this_disk;45 46 /* Number of the file containing the beginning of the central directory or47 * 0xFFFF if ZIP64 archive.48 */49 __u16 cd_disk;50 51 /* Number of central directory records on this disk or 0xFFFF if ZIP6452 * archive.53 */54 __u16 cd_records;55 56 /* Number of central directory records on all disks or 0xFFFF if ZIP6457 * archive.58 */59 __u16 cd_records_total;60 61 /* Size of the central directory record or 0xFFFFFFFF if ZIP64 archive. */62 __u32 cd_size;63 64 /* Offset of the central directory from the beginning of the archive or65 * 0xFFFFFFFF if ZIP64 archive.66 */67 __u32 cd_offset;68 69 /* Length of comment data following end of central directory record. */70 __u16 comment_length;71 72 /* Up to 64k of arbitrary bytes. */73 /* uint8_t comment[comment_length] */74} __attribute__((packed));75 76#define CD_FILE_HEADER_MAGIC 0x02014b5077#define FLAG_ENCRYPTED (1 << 0)78#define FLAG_HAS_DATA_DESCRIPTOR (1 << 3)79 80/* See section 4.3.12 of the spec. */81struct cd_file_header {82 /* Magic value equal to CD_FILE_HEADER_MAGIC. */83 __u32 magic;84 __u16 version;85 /* Minimum zip version needed to extract the file. */86 __u16 min_version;87 __u16 flags;88 __u16 compression;89 __u16 last_modified_time;90 __u16 last_modified_date;91 __u32 crc;92 __u32 compressed_size;93 __u32 uncompressed_size;94 __u16 file_name_length;95 __u16 extra_field_length;96 __u16 file_comment_length;97 /* Number of the disk where the file starts or 0xFFFF if ZIP64 archive. */98 __u16 disk;99 __u16 internal_attributes;100 __u32 external_attributes;101 /* Offset from the start of the disk containing the local file header to the102 * start of the local file header.103 */104 __u32 offset;105} __attribute__((packed));106 107#define LOCAL_FILE_HEADER_MAGIC 0x04034b50108 109/* See section 4.3.7 of the spec. */110struct local_file_header {111 /* Magic value equal to LOCAL_FILE_HEADER_MAGIC. */112 __u32 magic;113 /* Minimum zip version needed to extract the file. */114 __u16 min_version;115 __u16 flags;116 __u16 compression;117 __u16 last_modified_time;118 __u16 last_modified_date;119 __u32 crc;120 __u32 compressed_size;121 __u32 uncompressed_size;122 __u16 file_name_length;123 __u16 extra_field_length;124} __attribute__((packed));125 126#pragma GCC diagnostic pop127 128struct zip_archive {129 void *data;130 __u32 size;131 __u32 cd_offset;132 __u32 cd_records;133};134 135static void *check_access(struct zip_archive *archive, __u32 offset, __u32 size)136{137 if (offset + size > archive->size || offset > offset + size)138 return NULL;139 140 return archive->data + offset;141}142 143/* Returns 0 on success, -EINVAL on error and -ENOTSUP if the eocd indicates the144 * archive uses features which are not supported.145 */146static int try_parse_end_of_cd(struct zip_archive *archive, __u32 offset)147{148 __u16 comment_length, cd_records;149 struct end_of_cd_record *eocd;150 __u32 cd_offset, cd_size;151 152 eocd = check_access(archive, offset, sizeof(*eocd));153 if (!eocd || eocd->magic != END_OF_CD_RECORD_MAGIC)154 return -EINVAL;155 156 comment_length = eocd->comment_length;157 if (offset + sizeof(*eocd) + comment_length != archive->size)158 return -EINVAL;159 160 cd_records = eocd->cd_records;161 if (eocd->this_disk != 0 || eocd->cd_disk != 0 || eocd->cd_records_total != cd_records)162 /* This is a valid eocd, but we only support single-file non-ZIP64 archives. */163 return -ENOTSUP;164 165 cd_offset = eocd->cd_offset;166 cd_size = eocd->cd_size;167 if (!check_access(archive, cd_offset, cd_size))168 return -EINVAL;169 170 archive->cd_offset = cd_offset;171 archive->cd_records = cd_records;172 return 0;173}174 175static int find_cd(struct zip_archive *archive)176{177 int64_t limit, offset;178 int rc = -EINVAL;179 180 if (archive->size <= sizeof(struct end_of_cd_record))181 return -EINVAL;182 183 /* Because the end of central directory ends with a variable length array of184 * up to 0xFFFF bytes we can't know exactly where it starts and need to185 * search for it at the end of the file, scanning the (limit, offset] range.186 */187 offset = archive->size - sizeof(struct end_of_cd_record);188 limit = (int64_t)offset - (1 << 16);189 190 for (; offset >= 0 && offset > limit && rc != 0; offset--) {191 rc = try_parse_end_of_cd(archive, offset);192 if (rc == -ENOTSUP)193 break;194 }195 return rc;196}197 198struct zip_archive *zip_archive_open(const char *path)199{200 struct zip_archive *archive;201 int err, fd;202 off_t size;203 void *data;204 205 fd = open(path, O_RDONLY | O_CLOEXEC);206 if (fd < 0)207 return ERR_PTR(-errno);208 209 size = lseek(fd, 0, SEEK_END);210 if (size == (off_t)-1 || size > UINT32_MAX) {211 close(fd);212 return ERR_PTR(-EINVAL);213 }214 215 data = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);216 err = -errno;217 close(fd);218 219 if (data == MAP_FAILED)220 return ERR_PTR(err);221 222 archive = malloc(sizeof(*archive));223 if (!archive) {224 munmap(data, size);225 return ERR_PTR(-ENOMEM);226 };227 228 archive->data = data;229 archive->size = size;230 231 err = find_cd(archive);232 if (err) {233 munmap(data, size);234 free(archive);235 return ERR_PTR(err);236 }237 238 return archive;239}240 241void zip_archive_close(struct zip_archive *archive)242{243 munmap(archive->data, archive->size);244 free(archive);245}246 247static struct local_file_header *local_file_header_at_offset(struct zip_archive *archive,248 __u32 offset)249{250 struct local_file_header *lfh;251 252 lfh = check_access(archive, offset, sizeof(*lfh));253 if (!lfh || lfh->magic != LOCAL_FILE_HEADER_MAGIC)254 return NULL;255 256 return lfh;257}258 259static int get_entry_at_offset(struct zip_archive *archive, __u32 offset, struct zip_entry *out)260{261 struct local_file_header *lfh;262 __u32 compressed_size;263 const char *name;264 void *data;265 266 lfh = local_file_header_at_offset(archive, offset);267 if (!lfh)268 return -EINVAL;269 270 offset += sizeof(*lfh);271 if ((lfh->flags & FLAG_ENCRYPTED) || (lfh->flags & FLAG_HAS_DATA_DESCRIPTOR))272 return -EINVAL;273 274 name = check_access(archive, offset, lfh->file_name_length);275 if (!name)276 return -EINVAL;277 278 offset += lfh->file_name_length;279 if (!check_access(archive, offset, lfh->extra_field_length))280 return -EINVAL;281 282 offset += lfh->extra_field_length;283 compressed_size = lfh->compressed_size;284 data = check_access(archive, offset, compressed_size);285 if (!data)286 return -EINVAL;287 288 out->compression = lfh->compression;289 out->name_length = lfh->file_name_length;290 out->name = name;291 out->data = data;292 out->data_length = compressed_size;293 out->data_offset = offset;294 295 return 0;296}297 298int zip_archive_find_entry(struct zip_archive *archive, const char *file_name,299 struct zip_entry *out)300{301 size_t file_name_length = strlen(file_name);302 __u32 i, offset = archive->cd_offset;303 304 for (i = 0; i < archive->cd_records; ++i) {305 __u16 cdfh_name_length, cdfh_flags;306 struct cd_file_header *cdfh;307 const char *cdfh_name;308 309 cdfh = check_access(archive, offset, sizeof(*cdfh));310 if (!cdfh || cdfh->magic != CD_FILE_HEADER_MAGIC)311 return -EINVAL;312 313 offset += sizeof(*cdfh);314 cdfh_name_length = cdfh->file_name_length;315 cdfh_name = check_access(archive, offset, cdfh_name_length);316 if (!cdfh_name)317 return -EINVAL;318 319 cdfh_flags = cdfh->flags;320 if ((cdfh_flags & FLAG_ENCRYPTED) == 0 &&321 (cdfh_flags & FLAG_HAS_DATA_DESCRIPTOR) == 0 &&322 file_name_length == cdfh_name_length &&323 memcmp(file_name, archive->data + offset, file_name_length) == 0) {324 return get_entry_at_offset(archive, cdfh->offset, out);325 }326 327 offset += cdfh_name_length;328 offset += cdfh->extra_field_length;329 offset += cdfh->file_comment_length;330 }331 332 return -ENOENT;333}334