From 844fdd42f03a633f1dbce5d90b2ecf44698cf8b0 Mon Sep 17 00:00:00 2001 From: David Oberhollenzer Date: Fri, 18 Nov 2022 00:57:01 +0100 Subject: Add a single, central base64 decoder Similar to the hex blob decoder, we need this once for tar and once for the filemap xattr parser. Simply add a single, central implementation to libutil, with a simple unit test, and then use it in both libtar and gensquashfs. Signed-off-by: David Oberhollenzer --- lib/tar/pax_header.c | 62 +++++----------------------- lib/util/Makemodule.am | 1 + lib/util/base64_decode.c | 103 +++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 113 insertions(+), 53 deletions(-) create mode 100644 lib/util/base64_decode.c (limited to 'lib') diff --git a/lib/tar/pax_header.c b/lib/tar/pax_header.c index cc2f2b0..b61aab6 100644 --- a/lib/tar/pax_header.c +++ b/lib/tar/pax_header.c @@ -11,56 +11,6 @@ #include #include -static sqfs_u8 base64_convert(char in) -{ - if (isupper(in)) - return in - 'A'; - if (islower(in)) - return in - 'a' + 26; - if (isdigit(in)) - return in - '0' + 52; - if (in == '+') - return 62; - if (in == '/' || in == '-') - return 63; - return 0; -} - -static size_t base64_decode(sqfs_u8 *out, const char *in, size_t len) -{ - sqfs_u8 *start = out; - - while (len > 0) { - unsigned int diff = 0, value = 0; - - while (diff < 4 && len > 0) { - if (*in == '=' || *in == '_' || *in == '\0') { - len = 0; - } else { - value = (value << 6) | base64_convert(*(in++)); - --len; - ++diff; - } - } - - if (diff < 2) - break; - - value <<= 6 * (4 - diff); - - switch (diff) { - case 4: out[2] = value & 0xff; /* fall-through */ - case 3: out[1] = (value >> 8) & 0xff; /* fall-through */ - default: out[0] = (value >> 16) & 0xff; - } - - out += (diff * 3) / 4; - } - - *out = '\0'; - return out - start; -} - static int pax_read_decimal(const char *str, sqfs_u64 *out) { sqfs_u64 result = 0; @@ -201,10 +151,16 @@ static int pax_xattr_schily(tar_header_decoded_t *out, static int pax_xattr_libarchive(tar_header_decoded_t *out, tar_xattr_t *xattr) { + int ret; + + ret = base64_decode((const char *)xattr->value, xattr->value_len, + xattr->value, &xattr->value_len); + if (ret) + return -1; + urldecode(xattr->key); - xattr->value_len = base64_decode(xattr->value, - (const char *)xattr->value, - xattr->value_len); + + xattr->value[xattr->value_len] = '\0'; xattr->next = out->xattr; out->xattr = xattr; return 0; diff --git a/lib/util/Makemodule.am b/lib/util/Makemodule.am index 4f1f0da..ec38b7a 100644 --- a/lib/util/Makemodule.am +++ b/lib/util/Makemodule.am @@ -15,6 +15,7 @@ libutil_a_SOURCES += lib/util/filename_sane.c libutil_a_SOURCES += lib/util/source_date_epoch.c libutil_a_SOURCES += lib/util/file_cmp.c libutil_a_SOURCES += lib/util/hex_decode.c +libutil_a_SOURCES += lib/util/base64_decode.c libutil_a_CFLAGS = $(AM_CFLAGS) libutil_a_CPPFLAGS = $(AM_CPPFLAGS) diff --git a/lib/util/base64_decode.c b/lib/util/base64_decode.c new file mode 100644 index 0000000..b1cf5b6 --- /dev/null +++ b/lib/util/base64_decode.c @@ -0,0 +1,103 @@ +/* SPDX-License-Identifier: GPL-3.0-or-later */ +/* + * base64_decode.c + * + * Copyright (C) 2022 David Oberhollenzer + */ +#include "config.h" +#include "util/util.h" +#include "util/test.h" + +#include + +static int base64_digit(int c) +{ + if (isupper(c)) + return c - 'A'; + if (islower(c)) + return c - 'a' + 26; + if (isdigit(c)) + return c - '0' + 52; + if (c == '+') + return 62; + if (c == '/' || c == '-') + return 63; + return -1; +} + +int base64_decode(const char *in, size_t in_len, sqfs_u8 *out, size_t *out_len) +{ + int i1, i2, i3, i4; + size_t count = 0; + + while (in_len >= 4) { + i1 = base64_digit(*(in++)); + i2 = base64_digit(*(in++)); + i3 = *(in++); + i4 = *(in++); + in_len -= 4; + + if (i1 < 0 || i2 < 0 || count >= *out_len) + goto fail; + + out[count++] = (i1 << 2) | (i2 >> 4); + + if (i3 == '=' || i3 == '_') { + if ((i4 != '=' && i4 != '_') || in_len > 0) + goto fail; + break; + } + + i3 = base64_digit(i3); + if (i3 < 0 || count >= *out_len) + goto fail; + + out[count++] = ((i2 & 0x0F) << 4) | (i3 >> 2); + + if (i4 == '=' || i4 == '_') { + if (in_len > 0) + goto fail; + break; + } + + i4 = base64_digit(i4); + if (i4 < 0 || count >= *out_len) + goto fail; + + out[count++] = ((i3 & 0x3) << 6) | i4; + } + + /* libarchive has this bizarre bastardization of truncated base64 */ + if (in_len > 0) { + if (in_len == 1) + goto fail; + + i1 = base64_digit(*(in++)); + i2 = base64_digit(*(in++)); + in_len -= 2; + + if (i1 < 0 || i2 < 0 || count >= *out_len) + goto fail; + + out[count++] = (i1 << 2) | (i2 >> 4); + + if (in_len > 0) { + i3 = *(in++); + --in_len; + + if (i3 != '=' && i3 != '_') { + i3 = base64_digit(i3); + if (i3 < 0 || count >= *out_len) + goto fail; + + out[count++] = ((i2 & 0x0F) << 4) | (i3 >> 2); + } + } + } + + *out_len = count; + return 0; +fail: + *out_len = 0; + return -1; +} -- cgit v1.2.3