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unzip: properly use CDF to find compressed files. Closes 9536

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function                                             old     new   delta
unzip_main                                          2437    2350     -87

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2017-01-05 11:43:53 +01:00
parent 9c083f599a
commit e3c4db8b39
2 changed files with 167 additions and 122 deletions
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283
archival/unzip.c
View File

@ -16,7 +16,6 @@
* TODO
* Zip64 + other methods
*/
//config:config UNZIP
//config: bool "unzip"
//config: default y
@ -24,8 +23,17 @@
//config: unzip will list or extract files from a ZIP archive,
//config: commonly found on DOS/WIN systems. The default behavior
//config: (with no options) is to extract the archive into the
//config: current directory. Use the `-d' option to extract to a
//config: directory of your choice.
//config: current directory.
//config:
//config:config FEATURE_UNZIP_CDF
//config: bool "Read and use Central Directory data"
//config: default y
//config: depends on UNZIP
//config: help
//config: If you know that you only need to deal with simple
//config: ZIP files without deleted/updated files, SFX archves etc,
//config: you can reduce code size by unselecting this option.
//config: To support less trivial ZIPs, say Y.
//applet:IF_UNZIP(APPLET(unzip, BB_DIR_USR_BIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_UNZIP) += unzip.o
@ -80,30 +88,20 @@ typedef union {
uint32_t ucmpsize PACKED; /* 18-21 */
uint16_t filename_len; /* 22-23 */
uint16_t extra_len; /* 24-25 */
/* filename follows (not NUL terminated) */
/* extra field follows */
/* data follows */
} formatted PACKED;
} zip_header_t; /* PACKED - gcc 4.2.1 doesn't like it (spews warning) */
/* Check the offset of the last element, not the length. This leniency
* allows for poor packing, whereby the overall struct may be too long,
* even though the elements are all in the right place.
*/
struct BUG_zip_header_must_be_26_bytes {
char BUG_zip_header_must_be_26_bytes[
offsetof(zip_header_t, formatted.extra_len) + 2
== ZIP_HEADER_LEN ? 1 : -1];
};
#define FIX_ENDIANNESS_ZIP(zip_header) do { \
(zip_header).formatted.version = SWAP_LE16((zip_header).formatted.version ); \
(zip_header).formatted.method = SWAP_LE16((zip_header).formatted.method ); \
(zip_header).formatted.modtime = SWAP_LE16((zip_header).formatted.modtime ); \
(zip_header).formatted.moddate = SWAP_LE16((zip_header).formatted.moddate ); \
#define FIX_ENDIANNESS_ZIP(zip_header) \
do { if (BB_BIG_ENDIAN) { \
(zip_header).formatted.crc32 = SWAP_LE32((zip_header).formatted.crc32 ); \
(zip_header).formatted.cmpsize = SWAP_LE32((zip_header).formatted.cmpsize ); \
(zip_header).formatted.ucmpsize = SWAP_LE32((zip_header).formatted.ucmpsize ); \
(zip_header).formatted.filename_len = SWAP_LE16((zip_header).formatted.filename_len); \
(zip_header).formatted.extra_len = SWAP_LE16((zip_header).formatted.extra_len ); \
} while (0)
}} while (0)
#define CDF_HEADER_LEN 42
@ -115,8 +113,8 @@ typedef union {
uint16_t version_needed; /* 2-3 */
uint16_t cdf_flags; /* 4-5 */
uint16_t method; /* 6-7 */
uint16_t mtime; /* 8-9 */
uint16_t mdate; /* 10-11 */
uint16_t modtime; /* 8-9 */
uint16_t moddate; /* 10-11 */
uint32_t crc32; /* 12-15 */
uint32_t cmpsize; /* 16-19 */
uint32_t ucmpsize; /* 20-23 */
@ -127,27 +125,27 @@ typedef union {
uint16_t internal_file_attributes; /* 32-33 */
uint32_t external_file_attributes PACKED; /* 34-37 */
uint32_t relative_offset_of_local_header PACKED; /* 38-41 */
/* filename follows (not NUL terminated) */
/* extra field follows */
/* comment follows */
} formatted PACKED;
} cdf_header_t;
struct BUG_cdf_header_must_be_42_bytes {
char BUG_cdf_header_must_be_42_bytes[
offsetof(cdf_header_t, formatted.relative_offset_of_local_header) + 4
== CDF_HEADER_LEN ? 1 : -1];
};
#define FIX_ENDIANNESS_CDF(cdf_header) do { \
#define FIX_ENDIANNESS_CDF(cdf_header) \
do { if (BB_BIG_ENDIAN) { \
(cdf_header).formatted.version_made_by = SWAP_LE16((cdf_header).formatted.version_made_by); \
(cdf_header).formatted.version_needed = SWAP_LE16((cdf_header).formatted.version_needed); \
(cdf_header).formatted.method = SWAP_LE16((cdf_header).formatted.method ); \
(cdf_header).formatted.modtime = SWAP_LE16((cdf_header).formatted.modtime ); \
(cdf_header).formatted.moddate = SWAP_LE16((cdf_header).formatted.moddate ); \
(cdf_header).formatted.crc32 = SWAP_LE32((cdf_header).formatted.crc32 ); \
(cdf_header).formatted.cmpsize = SWAP_LE32((cdf_header).formatted.cmpsize ); \
(cdf_header).formatted.ucmpsize = SWAP_LE32((cdf_header).formatted.ucmpsize ); \
(cdf_header).formatted.file_name_length = SWAP_LE16((cdf_header).formatted.file_name_length); \
(cdf_header).formatted.extra_field_length = SWAP_LE16((cdf_header).formatted.extra_field_length); \
(cdf_header).formatted.file_comment_length = SWAP_LE16((cdf_header).formatted.file_comment_length); \
IF_DESKTOP( \
(cdf_header).formatted.version_made_by = SWAP_LE16((cdf_header).formatted.version_made_by); \
(cdf_header).formatted.external_file_attributes = SWAP_LE32((cdf_header).formatted.external_file_attributes); \
) \
} while (0)
}} while (0)
#define CDE_HEADER_LEN 16
@ -166,20 +164,38 @@ typedef union {
} formatted PACKED;
} cde_header_t;
struct BUG_cde_header_must_be_16_bytes {
#define FIX_ENDIANNESS_CDE(cde_header) \
do { if (BB_BIG_ENDIAN) { \
(cde_header).formatted.cdf_offset = SWAP_LE32((cde_header).formatted.cdf_offset); \
}} while (0)
struct BUG {
/* Check the offset of the last element, not the length. This leniency
* allows for poor packing, whereby the overall struct may be too long,
* even though the elements are all in the right place.
*/
char BUG_zip_header_must_be_26_bytes[
offsetof(zip_header_t, formatted.extra_len) + 2
== ZIP_HEADER_LEN ? 1 : -1];
char BUG_cdf_header_must_be_42_bytes[
offsetof(cdf_header_t, formatted.relative_offset_of_local_header) + 4
== CDF_HEADER_LEN ? 1 : -1];
char BUG_cde_header_must_be_16_bytes[
sizeof(cde_header_t) == CDE_HEADER_LEN ? 1 : -1];
};
#define FIX_ENDIANNESS_CDE(cde_header) do { \
(cde_header).formatted.cdf_offset = SWAP_LE32((cde_header).formatted.cdf_offset); \
} while (0)
enum { zip_fd = 3 };
#if ENABLE_DESKTOP
/* This value means that we failed to find CDF */
#define BAD_CDF_OFFSET ((uint32_t)0xffffffff)
#if !ENABLE_FEATURE_UNZIP_CDF
# define find_cdf_offset() BAD_CDF_OFFSET
#else
/* Seen in the wild:
* Self-extracting PRO2K3XP_32.exe contains 19078464 byte zip archive,
* where CDE was nearly 48 kbytes before EOF.
@ -188,25 +204,26 @@ enum { zip_fd = 3 };
* To make extraction work, bumped PEEK_FROM_END from 16k to 64k.
*/
#define PEEK_FROM_END (64*1024)
/* This value means that we failed to find CDF */
#define BAD_CDF_OFFSET ((uint32_t)0xffffffff)
/* NB: does not preserve file position! */
static uint32_t find_cdf_offset(void)
{
cde_header_t cde_header;
unsigned char *buf;
unsigned char *p;
off_t end;
unsigned char *buf = xzalloc(PEEK_FROM_END);
uint32_t found;
end = xlseek(zip_fd, 0, SEEK_END);
end = lseek(zip_fd, 0, SEEK_END);
if (end == (off_t) -1)
return BAD_CDF_OFFSET;
end -= PEEK_FROM_END;
if (end < 0)
end = 0;
dbg("Looking for cdf_offset starting from 0x%"OFF_FMT"x", end);
xlseek(zip_fd, end, SEEK_SET);
buf = xzalloc(PEEK_FROM_END);
full_read(zip_fd, buf, PEEK_FROM_END);
found = BAD_CDF_OFFSET;
@ -252,30 +269,36 @@ static uint32_t find_cdf_offset(void)
static uint32_t read_next_cdf(uint32_t cdf_offset, cdf_header_t *cdf_ptr)
{
off_t org;
uint32_t magic;
if (cdf_offset == BAD_CDF_OFFSET)
return cdf_offset;
org = xlseek(zip_fd, 0, SEEK_CUR);
if (!cdf_offset)
cdf_offset = find_cdf_offset();
if (cdf_offset != BAD_CDF_OFFSET) {
dbg("Reading CDF at 0x%x", (unsigned)cdf_offset);
xlseek(zip_fd, cdf_offset + 4, SEEK_SET);
xread(zip_fd, cdf_ptr->raw, CDF_HEADER_LEN);
FIX_ENDIANNESS_CDF(*cdf_ptr);
dbg(" file_name_length:%u extra_field_length:%u file_comment_length:%u",
(unsigned)cdf_ptr->formatted.file_name_length,
(unsigned)cdf_ptr->formatted.extra_field_length,
(unsigned)cdf_ptr->formatted.file_comment_length
);
cdf_offset += 4 + CDF_HEADER_LEN
+ cdf_ptr->formatted.file_name_length
+ cdf_ptr->formatted.extra_field_length
+ cdf_ptr->formatted.file_comment_length;
dbg("Reading CDF at 0x%x", (unsigned)cdf_offset);
xlseek(zip_fd, cdf_offset, SEEK_SET);
xread(zip_fd, &magic, 4);
/* Central Directory End? */
if (magic == ZIP_CDE_MAGIC) {
dbg("got ZIP_CDE_MAGIC");
return 0; /* EOF */
}
xread(zip_fd, cdf_ptr->raw, CDF_HEADER_LEN);
/* Caller doesn't need this: */
/* dbg("Returning file position to 0x%"OFF_FMT"x", org); */
/* xlseek(zip_fd, org, SEEK_SET); */
FIX_ENDIANNESS_CDF(*cdf_ptr);
dbg(" file_name_length:%u extra_field_length:%u file_comment_length:%u",
(unsigned)cdf_ptr->formatted.file_name_length,
(unsigned)cdf_ptr->formatted.extra_field_length,
(unsigned)cdf_ptr->formatted.file_comment_length
);
cdf_offset += 4 + CDF_HEADER_LEN
+ cdf_ptr->formatted.file_name_length
+ cdf_ptr->formatted.extra_field_length
+ cdf_ptr->formatted.file_comment_length;
dbg("Returning file position to 0x%"OFF_FMT"x", org);
xlseek(zip_fd, org, SEEK_SET);
return cdf_offset;
};
#endif
@ -324,6 +347,7 @@ static void unzip_extract(zip_header_t *zip_header, int dst_fd)
bb_error_msg("bad length");
}
}
/* TODO? method 12: bzip2, method 14: LZMA */
}
static void my_fgets80(char *buf80)
@ -339,15 +363,12 @@ int unzip_main(int argc, char **argv)
{
enum { O_PROMPT, O_NEVER, O_ALWAYS };
zip_header_t zip_header;
smallint quiet = 0;
IF_NOT_DESKTOP(const) smallint verbose = 0;
IF_NOT_FEATURE_UNZIP_CDF(const) smallint verbose = 0;
smallint listing = 0;
smallint overwrite = O_PROMPT;
smallint x_opt_seen;
#if ENABLE_DESKTOP
uint32_t cdf_offset;
#endif
unsigned long total_usize;
unsigned long total_size;
unsigned total_entries;
@ -430,7 +451,7 @@ int unzip_main(int argc, char **argv)
break;
case 'v': /* Verbose list */
IF_DESKTOP(verbose++;)
IF_FEATURE_UNZIP_CDF(verbose++;)
listing = 1;
break;
@ -545,78 +566,102 @@ int unzip_main(int argc, char **argv)
total_usize = 0;
total_size = 0;
total_entries = 0;
#if ENABLE_DESKTOP
cdf_offset = 0;
#endif
cdf_offset = find_cdf_offset(); /* try to seek to the end, find CDE and CDF start */
while (1) {
uint32_t magic;
zip_header_t zip_header;
mode_t dir_mode = 0777;
#if ENABLE_DESKTOP
#if ENABLE_FEATURE_UNZIP_CDF
mode_t file_mode = 0666;
#endif
/* Check magic number */
xread(zip_fd, &magic, 4);
/* Central directory? It's at the end, so exit */
if (magic == ZIP_CDF_MAGIC) {
dbg("got ZIP_CDF_MAGIC");
break;
}
#if ENABLE_DESKTOP
/* Data descriptor? It was a streaming file, go on */
if (magic == ZIP_DD_MAGIC) {
dbg("got ZIP_DD_MAGIC");
/* skip over duplicate crc32, cmpsize and ucmpsize */
unzip_skip(3 * 4);
continue;
}
#endif
if (magic != ZIP_FILEHEADER_MAGIC)
bb_error_msg_and_die("invalid zip magic %08X", (int)magic);
dbg("got ZIP_FILEHEADER_MAGIC");
if (!ENABLE_FEATURE_UNZIP_CDF || cdf_offset == BAD_CDF_OFFSET) {
/* Normally happens when input is unseekable.
*
* Valid ZIP file has Central Directory at the end
* with central directory file headers (CDFs).
* After it, there is a Central Directory End structure.
* CDFs identify what files are in the ZIP and where
* they are located. This allows ZIP readers to load
* the list of files without reading the entire ZIP archive.
* ZIP files may be appended to, only files specified in
* the CD are valid. Scanning for local file headers is
* not a correct algorithm.
*
* We try to do the above, and resort to "linear" reading
* of ZIP file only if seek failed or CDE wasn't found.
*/
uint32_t magic;
/* Read the file header */
xread(zip_fd, zip_header.raw, ZIP_HEADER_LEN);
FIX_ENDIANNESS_ZIP(zip_header);
if ((zip_header.formatted.method != 0) && (zip_header.formatted.method != 8)) {
bb_error_msg_and_die("unsupported method %d", zip_header.formatted.method);
}
#if !ENABLE_DESKTOP
if (zip_header.formatted.zip_flags & SWAP_LE16(0x0009)) {
bb_error_msg_and_die("zip flags 1 and 8 are not supported");
}
#else
if (zip_header.formatted.zip_flags & SWAP_LE16(0x0001)) {
/* 0x0001 - encrypted */
bb_error_msg_and_die("zip flag 1 (encryption) is not supported");
}
/* Check magic number */
xread(zip_fd, &magic, 4);
/* Central directory? It's at the end, so exit */
if (magic == ZIP_CDF_MAGIC) {
dbg("got ZIP_CDF_MAGIC");
break;
}
/* Data descriptor? It was a streaming file, go on */
if (magic == ZIP_DD_MAGIC) {
dbg("got ZIP_DD_MAGIC");
/* skip over duplicate crc32, cmpsize and ucmpsize */
unzip_skip(3 * 4);
continue;
}
if (magic != ZIP_FILEHEADER_MAGIC)
bb_error_msg_and_die("invalid zip magic %08X", (int)magic);
dbg("got ZIP_FILEHEADER_MAGIC");
if (cdf_offset != BAD_CDF_OFFSET) {
xread(zip_fd, zip_header.raw, ZIP_HEADER_LEN);
FIX_ENDIANNESS_ZIP(zip_header);
if ((zip_header.formatted.method != 0)
&& (zip_header.formatted.method != 8)
) {
/* TODO? method 12: bzip2, method 14: LZMA */
bb_error_msg_and_die("unsupported method %d", zip_header.formatted.method);
}
if (zip_header.formatted.zip_flags & SWAP_LE16(0x0009)) {
bb_error_msg_and_die("zip flags 1 and 8 are not supported");
}
}
#if ENABLE_FEATURE_UNZIP_CDF
else {
/* cdf_offset is valid (and we know the file is seekable) */
cdf_header_t cdf_header;
cdf_offset = read_next_cdf(cdf_offset, &cdf_header);
/*
* Note: cdf_offset can become BAD_CDF_OFFSET after the above call.
*/
if (cdf_offset == 0) /* EOF? */
break;
# if 0
xlseek(zip_fd,
SWAP_LE32(cdf_header.formatted.relative_offset_of_local_header) + 4,
SEEK_SET);
xread(zip_fd, zip_header.raw, ZIP_HEADER_LEN);
FIX_ENDIANNESS_ZIP(zip_header);
if (zip_header.formatted.zip_flags & SWAP_LE16(0x0008)) {
/* 0x0008 - streaming. [u]cmpsize can be reliably gotten
* only from Central Directory. See unzip_doc.txt
* only from Central Directory.
*/
zip_header.formatted.crc32 = cdf_header.formatted.crc32;
zip_header.formatted.cmpsize = cdf_header.formatted.cmpsize;
zip_header.formatted.ucmpsize = cdf_header.formatted.ucmpsize;
}
# else
/* CDF has the same data as local header, no need to read the latter */
memcpy(&zip_header.formatted.version,
&cdf_header.formatted.version_needed, ZIP_HEADER_LEN);
xlseek(zip_fd,
SWAP_LE32(cdf_header.formatted.relative_offset_of_local_header) + 4 + ZIP_HEADER_LEN,
SEEK_SET);
# endif
if ((cdf_header.formatted.version_made_by >> 8) == 3) {
/* This archive is created on Unix */
dir_mode = file_mode = (cdf_header.formatted.external_file_attributes >> 16);
}
}
if (cdf_offset == BAD_CDF_OFFSET
&& (zip_header.formatted.zip_flags & SWAP_LE16(0x0008))
) {
/* If it's a streaming zip, we _require_ CDF */
bb_error_msg_and_die("can't find file table");
}
#endif
if (zip_header.formatted.zip_flags & SWAP_LE16(0x0001)) {
/* 0x0001 - encrypted */
bb_error_msg_and_die("zip flag 1 (encryption) is not supported");
}
dbg("File cmpsize:0x%x extra_len:0x%x ucmpsize:0x%x",
(unsigned)zip_header.formatted.cmpsize,
(unsigned)zip_header.formatted.extra_len,
@ -751,7 +796,7 @@ int unzip_main(int argc, char **argv)
overwrite = O_ALWAYS;
case 'y': /* Open file and fall into unzip */
unzip_create_leading_dirs(dst_fn);
#if ENABLE_DESKTOP
#if ENABLE_FEATURE_UNZIP_CDF
dst_fd = xopen3(dst_fn, O_WRONLY | O_CREAT | O_TRUNC, file_mode);
#else
dst_fd = xopen(dst_fn, O_WRONLY | O_CREAT | O_TRUNC);

6
testsuite/unzip.tests
View File

@ -31,11 +31,10 @@ rmdir foo
rm foo.zip
# File containing some damaged encrypted stream
optional FEATURE_UNZIP_CDF
testing "unzip (bad archive)" "uudecode; unzip bad.zip 2>&1; echo \$?" \
"Archive: bad.zip
inflating: ]3j½r«IK-%Ix
unzip: corrupted data
unzip: inflate error
unzip: short read
1
" \
"" "\
@ -49,6 +48,7 @@ BDYAAAAMAAEADQAAADIADQAAAEEAAAASw73Ct1DKokohPXQiNzA+FAI1HCcW
NzITNFBLBQUKAC4JAA04Cw0EOhZQSwUGAQAABAIAAgCZAAAAeQAAAAIALhM=
====
"
SKIP=
rm *