diff options
Diffstat (limited to 'archival/libarchive/get_header_tar.c')
| -rw-r--r-- | archival/libarchive/get_header_tar.c | 461 |
1 files changed, 461 insertions, 0 deletions
diff --git a/archival/libarchive/get_header_tar.c b/archival/libarchive/get_header_tar.c new file mode 100644 index 000000000..78b0ae25f --- /dev/null +++ b/archival/libarchive/get_header_tar.c @@ -0,0 +1,461 @@ +/* vi: set sw=4 ts=4: */ +/* Licensed under GPLv2 or later, see file LICENSE in this source tree. + * + * FIXME: + * In privileged mode if uname and gname map to a uid and gid then use the + * mapped value instead of the uid/gid values in tar header + * + * References: + * GNU tar and star man pages, + * Opengroup's ustar interchange format, + * http://www.opengroup.org/onlinepubs/007904975/utilities/pax.html + */ + +#include "libbb.h" +#include "archive.h" + +typedef uint32_t aliased_uint32_t FIX_ALIASING; +typedef off_t aliased_off_t FIX_ALIASING; + + +/* NB: _DESTROYS_ str[len] character! */ +static unsigned long long getOctal(char *str, int len) +{ + unsigned long long v; + char *end; + /* NB: leading spaces are allowed. Using strtoull to handle that. + * The downside is that we accept e.g. "-123" too :( + */ + str[len] = '\0'; + v = strtoull(str, &end, 8); + /* std: "Each numeric field is terminated by one or more + * <space> or NUL characters". We must support ' '! */ + if (*end != '\0' && *end != ' ') { + int8_t first = str[0]; + if (!(first & 0x80)) + bb_error_msg_and_die("corrupted octal value in tar header"); + /* + * GNU tar uses "base-256 encoding" for very large numbers. + * Encoding is binary, with highest bit always set as a marker + * and sign in next-highest bit: + * 80 00 .. 00 - zero + * bf ff .. ff - largest positive number + * ff ff .. ff - minus 1 + * c0 00 .. 00 - smallest negative number + * + * Example of tar file with 8914993153 (0x213600001) byte file. + * Field starts at offset 7c: + * 00070 30 30 30 00 30 30 30 30 30 30 30 00 80 00 00 00 |000.0000000.....| + * 00080 00 00 00 02 13 60 00 01 31 31 31 32 30 33 33 36 |.....`..11120336| + * + * NB: tarballs with NEGATIVE unix times encoded that way were seen! + */ + v = first; + /* Sign-extend using 6th bit: */ + v <<= sizeof(unsigned long long)*8 - 7; + v = (long long)v >> (sizeof(unsigned long long)*8 - 7); + while (--len != 0) + v = (v << 8) + (unsigned char) *str++; + } + return v; +} +#define GET_OCTAL(a) getOctal((a), sizeof(a)) + +#if ENABLE_FEATURE_TAR_SELINUX +/* Scan a PAX header for SELinux contexts, via "RHT.security.selinux" keyword. + * This is what Red Hat's patched version of tar uses. + */ +# define SELINUX_CONTEXT_KEYWORD "RHT.security.selinux" +static char *get_selinux_sctx_from_pax_hdr(archive_handle_t *archive_handle, unsigned sz) +{ + char *buf, *p; + char *result; + + p = buf = xmalloc(sz + 1); + /* prevent bb_strtou from running off the buffer */ + buf[sz] = '\0'; + xread(archive_handle->src_fd, buf, sz); + archive_handle->offset += sz; + + result = NULL; + while (sz != 0) { + char *end, *value; + unsigned len; + + /* Every record has this format: "LEN NAME=VALUE\n" */ + len = bb_strtou(p, &end, 10); + /* expect errno to be EINVAL, because the character + * following the digits should be a space + */ + p += len; + sz -= len; + if ((int)sz < 0 + || len == 0 + || errno != EINVAL + || *end != ' ' + ) { + bb_error_msg("malformed extended header, skipped"); + // More verbose version: + //bb_error_msg("malformed extended header at %"OFF_FMT"d, skipped", + // archive_handle->offset - (sz + len)); + break; + } + /* overwrite the terminating newline with NUL + * (we do not bother to check that it *was* a newline) + */ + p[-1] = '\0'; + /* Is it selinux security context? */ + value = end + 1; + if (strncmp(value, SELINUX_CONTEXT_KEYWORD"=", sizeof(SELINUX_CONTEXT_KEYWORD"=") - 1) == 0) { + value += sizeof(SELINUX_CONTEXT_KEYWORD"=") - 1; + result = xstrdup(value); + break; + } + } + + free(buf); + return result; +} +#endif + +char FAST_FUNC get_header_tar(archive_handle_t *archive_handle) +{ + file_header_t *file_header = archive_handle->file_header; + struct tar_header_t tar; + char *cp; + int i, sum_u, sum; +#if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY + int sum_s; +#endif + int parse_names; + + /* Our "private data" */ +#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS +# define p_longname (archive_handle->tar__longname) +# define p_linkname (archive_handle->tar__linkname) +#else +# define p_longname 0 +# define p_linkname 0 +#endif + +#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS || ENABLE_FEATURE_TAR_SELINUX + again: +#endif + /* Align header */ + data_align(archive_handle, 512); + + again_after_align: + +#if ENABLE_DESKTOP || ENABLE_FEATURE_TAR_AUTODETECT + /* to prevent misdetection of bz2 sig */ + *(aliased_uint32_t*)&tar = 0; + i = full_read(archive_handle->src_fd, &tar, 512); + /* If GNU tar sees EOF in above read, it says: + * "tar: A lone zero block at N", where N = kilobyte + * where EOF was met (not EOF block, actual EOF!), + * and exits with EXIT_SUCCESS. + * We will mimic exit(EXIT_SUCCESS), although we will not mimic + * the message and we don't check whether we indeed + * saw zero block directly before this. */ + if (i == 0) { + xfunc_error_retval = 0; + short_read: + bb_error_msg_and_die("short read"); + } + if (i != 512) { + IF_FEATURE_TAR_AUTODETECT(goto autodetect;) + goto short_read; + } + +#else + i = 512; + xread(archive_handle->src_fd, &tar, i); +#endif + archive_handle->offset += i; + + /* If there is no filename its an empty header */ + if (tar.name[0] == 0 && tar.prefix[0] == 0) { + if (archive_handle->tar__end) { + /* Second consecutive empty header - end of archive. + * Read until the end to empty the pipe from gz or bz2 + */ + while (full_read(archive_handle->src_fd, &tar, 512) == 512) + continue; + return EXIT_FAILURE; + } + archive_handle->tar__end = 1; + return EXIT_SUCCESS; + } + archive_handle->tar__end = 0; + + /* Check header has valid magic, "ustar" is for the proper tar, + * five NULs are for the old tar format */ + if (strncmp(tar.magic, "ustar", 5) != 0 + && (!ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY + || memcmp(tar.magic, "\0\0\0\0", 5) != 0) + ) { +#if ENABLE_FEATURE_TAR_AUTODETECT + char FAST_FUNC (*get_header_ptr)(archive_handle_t *); + uint16_t magic2; + + autodetect: + magic2 = *(uint16_t*)tar.name; + /* tar gz/bz autodetect: check for gz/bz2 magic. + * If we see the magic, and it is the very first block, + * we can switch to get_header_tar_gz/bz2/lzma(). + * Needs seekable fd. I wish recv(MSG_PEEK) works + * on any fd... */ +# if ENABLE_FEATURE_SEAMLESS_GZ + if (magic2 == GZIP_MAGIC) { + get_header_ptr = get_header_tar_gz; + } else +# endif +# if ENABLE_FEATURE_SEAMLESS_BZ2 + if (magic2 == BZIP2_MAGIC + && tar.name[2] == 'h' && isdigit(tar.name[3]) + ) { /* bzip2 */ + get_header_ptr = get_header_tar_bz2; + } else +# endif +# if ENABLE_FEATURE_SEAMLESS_XZ + //TODO: if (magic2 == XZ_MAGIC1)... + //else +# endif + goto err; + /* Two different causes for lseek() != 0: + * unseekable fd (would like to support that too, but...), + * or not first block (false positive, it's not .gz/.bz2!) */ + if (lseek(archive_handle->src_fd, -i, SEEK_CUR) != 0) + goto err; + while (get_header_ptr(archive_handle) == EXIT_SUCCESS) + continue; + return EXIT_FAILURE; + err: +#endif /* FEATURE_TAR_AUTODETECT */ + bb_error_msg_and_die("invalid tar magic"); + } + + /* Do checksum on headers. + * POSIX says that checksum is done on unsigned bytes, but + * Sun and HP-UX gets it wrong... more details in + * GNU tar source. */ +#if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY + sum_s = ' ' * sizeof(tar.chksum); +#endif + sum_u = ' ' * sizeof(tar.chksum); + for (i = 0; i < 148; i++) { + sum_u += ((unsigned char*)&tar)[i]; +#if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY + sum_s += ((signed char*)&tar)[i]; +#endif + } + for (i = 156; i < 512; i++) { + sum_u += ((unsigned char*)&tar)[i]; +#if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY + sum_s += ((signed char*)&tar)[i]; +#endif + } + /* This field does not need special treatment (getOctal) */ + { + char *endp; /* gcc likes temp var for &endp */ + sum = strtoul(tar.chksum, &endp, 8); + if ((*endp != '\0' && *endp != ' ') + || (sum_u != sum IF_FEATURE_TAR_OLDSUN_COMPATIBILITY(&& sum_s != sum)) + ) { + bb_error_msg_and_die("invalid tar header checksum"); + } + } + /* don't use xstrtoul, tar.chksum may have leading spaces */ + sum = strtoul(tar.chksum, NULL, 8); + if (sum_u != sum IF_FEATURE_TAR_OLDSUN_COMPATIBILITY(&& sum_s != sum)) { + bb_error_msg_and_die("invalid tar header checksum"); + } + + /* 0 is reserved for high perf file, treat as normal file */ + if (!tar.typeflag) tar.typeflag = '0'; + parse_names = (tar.typeflag >= '0' && tar.typeflag <= '7'); + + /* getOctal trashes subsequent field, therefore we call it + * on fields in reverse order */ + if (tar.devmajor[0]) { + char t = tar.prefix[0]; + /* we trash prefix[0] here, but we DO need it later! */ + unsigned minor = GET_OCTAL(tar.devminor); + unsigned major = GET_OCTAL(tar.devmajor); + file_header->device = makedev(major, minor); + tar.prefix[0] = t; + } + file_header->link_target = NULL; + if (!p_linkname && parse_names && tar.linkname[0]) { + file_header->link_target = xstrndup(tar.linkname, sizeof(tar.linkname)); + /* FIXME: what if we have non-link object with link_target? */ + /* Will link_target be free()ed? */ + } +#if ENABLE_FEATURE_TAR_UNAME_GNAME + file_header->tar__uname = tar.uname[0] ? xstrndup(tar.uname, sizeof(tar.uname)) : NULL; + file_header->tar__gname = tar.gname[0] ? xstrndup(tar.gname, sizeof(tar.gname)) : NULL; +#endif + file_header->mtime = GET_OCTAL(tar.mtime); + file_header->size = GET_OCTAL(tar.size); + file_header->gid = GET_OCTAL(tar.gid); + file_header->uid = GET_OCTAL(tar.uid); + /* Set bits 0-11 of the files mode */ + file_header->mode = 07777 & GET_OCTAL(tar.mode); + + file_header->name = NULL; + if (!p_longname && parse_names) { + /* we trash mode[0] here, it's ok */ + //tar.name[sizeof(tar.name)] = '\0'; - gcc 4.3.0 would complain + tar.mode[0] = '\0'; + if (tar.prefix[0]) { + /* and padding[0] */ + //tar.prefix[sizeof(tar.prefix)] = '\0'; - gcc 4.3.0 would complain + tar.padding[0] = '\0'; + file_header->name = concat_path_file(tar.prefix, tar.name); + } else + file_header->name = xstrdup(tar.name); + } + + /* Set bits 12-15 of the files mode */ + /* (typeflag was not trashed because chksum does not use getOctal) */ + switch (tar.typeflag) { + /* busybox identifies hard links as being regular files with 0 size and a link name */ + case '1': + file_header->mode |= S_IFREG; + break; + case '7': + /* case 0: */ + case '0': +#if ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY + if (last_char_is(file_header->name, '/')) { + goto set_dir; + } +#endif + file_header->mode |= S_IFREG; + break; + case '2': + file_header->mode |= S_IFLNK; + /* have seen tarballs with size field containing + * the size of the link target's name */ + size0: + file_header->size = 0; + break; + case '3': + file_header->mode |= S_IFCHR; + goto size0; /* paranoia */ + case '4': + file_header->mode |= S_IFBLK; + goto size0; + case '5': + IF_FEATURE_TAR_OLDGNU_COMPATIBILITY(set_dir:) + file_header->mode |= S_IFDIR; + goto size0; + case '6': + file_header->mode |= S_IFIFO; + goto size0; +#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS + case 'L': + /* free: paranoia: tar with several consecutive longnames */ + free(p_longname); + /* For paranoia reasons we allocate extra NUL char */ + p_longname = xzalloc(file_header->size + 1); + /* We read ASCIZ string, including NUL */ + xread(archive_handle->src_fd, p_longname, file_header->size); + archive_handle->offset += file_header->size; + /* return get_header_tar(archive_handle); */ + /* gcc 4.1.1 didn't optimize it into jump */ + /* so we will do it ourself, this also saves stack */ + goto again; + case 'K': + free(p_linkname); + p_linkname = xzalloc(file_header->size + 1); + xread(archive_handle->src_fd, p_linkname, file_header->size); + archive_handle->offset += file_header->size; + /* return get_header_tar(archive_handle); */ + goto again; + case 'D': /* GNU dump dir */ + case 'M': /* Continuation of multi volume archive */ + case 'N': /* Old GNU for names > 100 characters */ + case 'S': /* Sparse file */ + case 'V': /* Volume header */ +#endif +#if !ENABLE_FEATURE_TAR_SELINUX + case 'g': /* pax global header */ + case 'x': /* pax extended header */ +#else + skip_ext_hdr: +#endif + { + off_t sz; + bb_error_msg("warning: skipping header '%c'", tar.typeflag); + sz = (file_header->size + 511) & ~(off_t)511; + archive_handle->offset += sz; + sz >>= 9; /* sz /= 512 but w/o contortions for signed div */ + while (sz--) + xread(archive_handle->src_fd, &tar, 512); + /* return get_header_tar(archive_handle); */ + goto again_after_align; + } +#if ENABLE_FEATURE_TAR_SELINUX + case 'g': /* pax global header */ + case 'x': { /* pax extended header */ + char **pp; + if ((uoff_t)file_header->size > 0xfffff) /* paranoia */ + goto skip_ext_hdr; + pp = (tar.typeflag == 'g') ? &archive_handle->tar__global_sctx : &archive_handle->tar__next_file_sctx; + free(*pp); + *pp = get_selinux_sctx_from_pax_hdr(archive_handle, file_header->size); + goto again; + } +#endif + default: + bb_error_msg_and_die("unknown typeflag: 0x%x", tar.typeflag); + } + +#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS + if (p_longname) { + file_header->name = p_longname; + p_longname = NULL; + } + if (p_linkname) { + file_header->link_target = p_linkname; + p_linkname = NULL; + } +#endif + if (strncmp(file_header->name, "/../"+1, 3) == 0 + || strstr(file_header->name, "/../") + ) { + bb_error_msg_and_die("name with '..' encountered: '%s'", + file_header->name); + } + + /* Strip trailing '/' in directories */ + /* Must be done after mode is set as '/' is used to check if it's a directory */ + cp = last_char_is(file_header->name, '/'); + + if (archive_handle->filter(archive_handle) == EXIT_SUCCESS) { + archive_handle->action_header(/*archive_handle->*/ file_header); + /* Note that we kill the '/' only after action_header() */ + /* (like GNU tar 1.15.1: verbose mode outputs "dir/dir/") */ + if (cp) + *cp = '\0'; + archive_handle->action_data(archive_handle); + if (archive_handle->accept || archive_handle->reject) + llist_add_to(&archive_handle->passed, file_header->name); + else /* Caller isn't interested in list of unpacked files */ + free(file_header->name); + } else { + data_skip(archive_handle); + free(file_header->name); + } + archive_handle->offset += file_header->size; + + free(file_header->link_target); + /* Do not free(file_header->name)! + * It might be inserted in archive_handle->passed - see above */ +#if ENABLE_FEATURE_TAR_UNAME_GNAME + free(file_header->tar__uname); + free(file_header->tar__gname); +#endif + return EXIT_SUCCESS; +} |