1 // SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
3 * Routines for dealing with .zip archives.
5 * Copyright (c) Meta Platforms, Inc. and affiliates.
16 #include "libbpf_internal.h"
19 #pragma GCC diagnostic push
20 #pragma GCC diagnostic ignored "-Wpacked"
21 #pragma GCC diagnostic ignored "-Wattributes"
23 /* Specification of ZIP file format can be found here:
24 * https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT
25 * For a high level overview of the structure of a ZIP file see
26 * sections 4.3.1 - 4.3.6.
28 * Data structures appearing in ZIP files do not contain any
29 * padding and they might be misaligned. To allow us to safely
30 * operate on pointers to such structures and their members, we
31 * declare the types as packed.
34 #define END_OF_CD_RECORD_MAGIC 0x06054b50
36 /* See section 4.3.16 of the spec. */
37 struct end_of_cd_record {
38 /* Magic value equal to END_OF_CD_RECORD_MAGIC */
41 /* Number of the file containing this structure or 0xFFFF if ZIP64 archive.
42 * Zip archive might span multiple files (disks).
46 /* Number of the file containing the beginning of the central directory or
47 * 0xFFFF if ZIP64 archive.
51 /* Number of central directory records on this disk or 0xFFFF if ZIP64
56 /* Number of central directory records on all disks or 0xFFFF if ZIP64
59 __u16 cd_records_total;
61 /* Size of the central directory record or 0xFFFFFFFF if ZIP64 archive. */
64 /* Offset of the central directory from the beginning of the archive or
65 * 0xFFFFFFFF if ZIP64 archive.
69 /* Length of comment data following end of central directory record. */
72 /* Up to 64k of arbitrary bytes. */
73 /* uint8_t comment[comment_length] */
74 } __attribute__((packed));
76 #define CD_FILE_HEADER_MAGIC 0x02014b50
77 #define FLAG_ENCRYPTED (1 << 0)
78 #define FLAG_HAS_DATA_DESCRIPTOR (1 << 3)
80 /* See section 4.3.12 of the spec. */
81 struct cd_file_header {
82 /* Magic value equal to CD_FILE_HEADER_MAGIC. */
85 /* Minimum zip version needed to extract the file. */
89 __u16 last_modified_time;
90 __u16 last_modified_date;
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. */
99 __u16 internal_attributes;
100 __u32 external_attributes;
101 /* Offset from the start of the disk containing the local file header to the
102 * start of the local file header.
105 } __attribute__((packed));
107 #define LOCAL_FILE_HEADER_MAGIC 0x04034b50
109 /* See section 4.3.7 of the spec. */
110 struct local_file_header {
111 /* Magic value equal to LOCAL_FILE_HEADER_MAGIC. */
113 /* Minimum zip version needed to extract the file. */
117 __u16 last_modified_time;
118 __u16 last_modified_date;
120 __u32 compressed_size;
121 __u32 uncompressed_size;
122 __u16 file_name_length;
123 __u16 extra_field_length;
124 } __attribute__((packed));
126 #pragma GCC diagnostic pop
135 static void *check_access(struct zip_archive *archive, __u32 offset, __u32 size)
137 if (offset + size > archive->size || offset > offset + size)
140 return archive->data + offset;
143 /* Returns 0 on success, -EINVAL on error and -ENOTSUP if the eocd indicates the
144 * archive uses features which are not supported.
146 static int try_parse_end_of_cd(struct zip_archive *archive, __u32 offset)
148 __u16 comment_length, cd_records;
149 struct end_of_cd_record *eocd;
150 __u32 cd_offset, cd_size;
152 eocd = check_access(archive, offset, sizeof(*eocd));
153 if (!eocd || eocd->magic != END_OF_CD_RECORD_MAGIC)
156 comment_length = eocd->comment_length;
157 if (offset + sizeof(*eocd) + comment_length != archive->size)
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. */
165 cd_offset = eocd->cd_offset;
166 cd_size = eocd->cd_size;
167 if (!check_access(archive, cd_offset, cd_size))
170 archive->cd_offset = cd_offset;
171 archive->cd_records = cd_records;
175 static int find_cd(struct zip_archive *archive)
177 int64_t limit, offset;
180 if (archive->size <= sizeof(struct end_of_cd_record))
183 /* Because the end of central directory ends with a variable length array of
184 * up to 0xFFFF bytes we can't know exactly where it starts and need to
185 * search for it at the end of the file, scanning the (limit, offset] range.
187 offset = archive->size - sizeof(struct end_of_cd_record);
188 limit = (int64_t)offset - (1 << 16);
190 for (; offset >= 0 && offset > limit && rc != 0; offset--) {
191 rc = try_parse_end_of_cd(archive, offset);
198 struct zip_archive *zip_archive_open(const char *path)
200 struct zip_archive *archive;
205 fd = open(path, O_RDONLY | O_CLOEXEC);
207 return ERR_PTR(-errno);
209 size = lseek(fd, 0, SEEK_END);
210 if (size == (off_t)-1 || size > UINT32_MAX) {
212 return ERR_PTR(-EINVAL);
215 data = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
219 if (data == MAP_FAILED)
222 archive = malloc(sizeof(*archive));
225 return ERR_PTR(-ENOMEM);
228 archive->data = data;
229 archive->size = size;
231 err = find_cd(archive);
241 void zip_archive_close(struct zip_archive *archive)
243 munmap(archive->data, archive->size);
247 static struct local_file_header *local_file_header_at_offset(struct zip_archive *archive,
250 struct local_file_header *lfh;
252 lfh = check_access(archive, offset, sizeof(*lfh));
253 if (!lfh || lfh->magic != LOCAL_FILE_HEADER_MAGIC)
259 static int get_entry_at_offset(struct zip_archive *archive, __u32 offset, struct zip_entry *out)
261 struct local_file_header *lfh;
262 __u32 compressed_size;
266 lfh = local_file_header_at_offset(archive, offset);
270 offset += sizeof(*lfh);
271 if ((lfh->flags & FLAG_ENCRYPTED) || (lfh->flags & FLAG_HAS_DATA_DESCRIPTOR))
274 name = check_access(archive, offset, lfh->file_name_length);
278 offset += lfh->file_name_length;
279 if (!check_access(archive, offset, lfh->extra_field_length))
282 offset += lfh->extra_field_length;
283 compressed_size = lfh->compressed_size;
284 data = check_access(archive, offset, compressed_size);
288 out->compression = lfh->compression;
289 out->name_length = lfh->file_name_length;
292 out->data_length = compressed_size;
293 out->data_offset = offset;
298 int zip_archive_find_entry(struct zip_archive *archive, const char *file_name,
299 struct zip_entry *out)
301 size_t file_name_length = strlen(file_name);
302 __u32 i, offset = archive->cd_offset;
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;
309 cdfh = check_access(archive, offset, sizeof(*cdfh));
310 if (!cdfh || cdfh->magic != CD_FILE_HEADER_MAGIC)
313 offset += sizeof(*cdfh);
314 cdfh_name_length = cdfh->file_name_length;
315 cdfh_name = check_access(archive, offset, cdfh_name_length);
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);
327 offset += cdfh_name_length;
328 offset += cdfh->extra_field_length;
329 offset += cdfh->file_comment_length;