The right implementation of CGPT label conversion between UTF8 and UTF16.
For security quick fix, the original UTF8/UTF16 conversion only supports
ASCII area. This CL extends the library to support multiple code units
conversion between UTF8 and UTF16. The UTF8/UTF16 encoded byte(s) would be
decoded to code point first, then be encoded to UTF16/UTF8 correspondingly.
Bill, please kindly review the UTF8/UTF16 conversion.
Peter, please kindly comment if any security concern.
Thanks.
Change-Id: I99c558ff27556e0b8635ba2b8d9925d042e75cb2
BUG=chromium-os:7542
TEST=RUNTESTS=1 emerge-x86-generic vboot_reference
Manually tested the following commands (intentionally mix Chinese and ASCII):
export C=.../cgpt
export D=/tmp/hda
$C add $D -i 1 -l 批P踢T踢T許C夕C餐
$C find $D -l 批P踢T踢T許C夕C餐
$C show $D
$C add $D -i 1 -l 批P踢T踢T許C夕C餐
$C find $D -l 批P踢T踢T許C夕C餐
$C add $D -i 1 -l abc012
$C add $D -i 1 -l 是否看過坊間常見的許茹芸淚海慶功宴吃蓋飯第四集
$C add $D -i 1 -l 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ # ok and truncated
$C add $D -i 1 -l `printf "\xf4\x91\x81\x81"` # (EXPECT: failed)
$C add $D -i 1 -l `printf "\xf4\x8f\xbf\xbf"`
$C add $D -i 1 -l `printf "\xf4\x8f\x44\x44"` # (EXPECT: failed)
$C add $D -i 1 -l `printf "\xf4\x8f\xbf"` # (EXPECT: failed)
$C add $D -i 1 -l `printf "\xf0\xbf\xbf\xbf"`
$C add $D -i 1 -l `printf "\xf0\xbf\xbf\x44"` # (EXPECT: failed)
$C add $D -i 1 -l `printf "\xf0\x80\x80\x80"` # (EXPECT: failed)
$C add $D -i 1 -l `printf "\xf0\x80\x84\x80"` # (EXPECT: failed)
$C add $D -i 1 -l `printf "\xf0\x80\x90\x80"` # (EXPECT: failed)
$C add $D -i 1 -l `printf "\xf0\x88\x80\x80"` # (EXPECT: failed)
$C add $D -i 1 -l `printf "\xed\x80\x80"`
$C add $D -i 1 -l `printf "\xed\xa0\x80"` # (EXPECT: failed)
$C add $D -i 1 -l `printf "\xe0\xbf\xbf"`
$C add $D -i 1 -l `printf "\xe0\xbf\x44"` # (EXPECT: failed)
$C add $D -i 1 -l `printf "\xe0\x80\x80"` # (EXPECT: failed)
$C add $D -i 1 -l `printf "\xe0\x90\x80"` # (EXPECT: failed)
$C add $D -i 1 -l `printf "\xe0\xbf"` # (EXPECT: failed)
$C add $D -i 1 -l `printf "\xd0\x80"`
$C add $D -i 1 -l `printf "\xd0\x11"` # (EXPECT: failed)
$C add $D -i 1 -l `printf "\xd0"` # (EXPECT: failed)
$C add $D -i 1 -l `printf "\xc0\xaf"` # (EXPECT: failed)
$C add $D -i 1 -l `printf "\x80"` # (EXPECT: failed)
Review URL: http://codereview.chromium.org/5025003
diff --git a/cgpt/cgpt.h b/cgpt/cgpt.h
index 9b0805c..85702a4 100644
--- a/cgpt/cgpt.h
+++ b/cgpt/cgpt.h
@@ -81,14 +81,22 @@
/* Convert possibly unterminated UTF16 string to UTF8.
* Caller must prepare enough space for UTF8, which could be up to
- * twice the number of UTF16 chars plus the terminating '\0'.
+ * twice the byte length of UTF16 string plus the terminating '\0'.
+ *
+ * Return: CGPT_OK --- all character are converted successfully.
+ * CGPT_FAILED --- convert error, i.e. output buffer is too short.
*/
-void UTF16ToUTF8(const uint16_t *utf16, unsigned int maxinput,
- uint8_t *utf8, unsigned int maxoutput);
+int UTF16ToUTF8(const uint16_t *utf16, unsigned int maxinput,
+ uint8_t *utf8, unsigned int maxoutput);
+
/* Convert null-terminated UTF8 string to UTF16.
- * Caller must prepare enough space for UTF16, including a terminating 0x0000
+ * Caller must prepare enough space for UTF16, which is the byte length of UTF8
+ * plus the terminating 0x0000.
+ *
+ * Return: CGPT_OK --- all character are converted successfully.
+ * CGPT_FAILED --- convert error, i.e. output buffer is too short.
*/
-void UTF8ToUTF16(const uint8_t *utf8, uint16_t *utf16, unsigned int maxoutput);
+int UTF8ToUTF16(const uint8_t *utf8, uint16_t *utf16, unsigned int maxoutput);
/* Helper functions for supported GPT types. */
int ResolveType(const Guid *type, char *buf);
diff --git a/cgpt/cgpt_common.c b/cgpt/cgpt_common.c
index 0e466fd..52cbe70 100644
--- a/cgpt/cgpt_common.c
+++ b/cgpt/cgpt_common.c
@@ -350,56 +350,209 @@
/* Convert possibly unterminated UTF16 string to UTF8.
* Caller must prepare enough space for UTF8, which could be up to
- * twice the number of UTF16 chars plus the terminating '\0'.
- * FIXME(wfrichar): The original implementation had security issues. As a
- * temporary fix, I'm making this ONLY support ASCII codepoints. Bug 7542
- * (http://code.google.com/p/chromium-os/issues/detail?id=7542) is filed to fix
- * this.
+ * twice the byte length of UTF16 string plus the terminating '\0'.
+ * See the following table for encoding lengths.
+ *
+ * Code point UTF16 UTF8
+ * 0x0000-0x007F 2 bytes 1 byte
+ * 0x0080-0x07FF 2 bytes 2 bytes
+ * 0x0800-0xFFFF 2 bytes 3 bytes
+ * 0x10000-0x10FFFF 4 bytes 4 bytes
+ *
+ * This function uses a simple state meachine to convert UTF-16 char(s) to
+ * a code point. Once a code point is parsed out, the state machine throws
+ * out sequencial UTF-8 chars in one time.
+ *
+ * Return: CGPT_OK --- all character are converted successfully.
+ * CGPT_FAILED --- convert error, i.e. output buffer is too short.
*/
-void UTF16ToUTF8(const uint16_t *utf16, unsigned int maxinput,
- uint8_t *utf8, unsigned int maxoutput)
+int UTF16ToUTF8(const uint16_t *utf16, unsigned int maxinput,
+ uint8_t *utf8, unsigned int maxoutput)
{
size_t s16idx, s8idx;
- uint32_t utfchar;
+ uint32_t code_point;
+ int code_point_ready = 1; // code point is ready to output.
+ int retval = CGPT_OK;
if (!utf16 || !maxinput || !utf8 || !maxoutput)
- return;
+ return CGPT_FAILED;
maxoutput--; /* plan for termination now */
for (s16idx = s8idx = 0;
s16idx < maxinput && utf16[s16idx] && maxoutput;
- s16idx++, maxoutput--) {
- utfchar = le16toh(utf16[s16idx]);
- utf8[s8idx++] = utfchar & 0x7F;
+ s16idx++) {
+ uint16_t codeunit = le16toh(utf16[s16idx]);
+
+ if (code_point_ready) {
+ if (codeunit >= 0xD800 && codeunit <= 0xDBFF) {
+ /* high surrogate, need the low surrogate. */
+ code_point_ready = 0;
+ code_point = (codeunit & 0x03FF) + 0x0040;
+ } else {
+ /* BMP char, output it. */
+ code_point = codeunit;
+ }
+ } else {
+ /* expect the low surrogate */
+ if (codeunit >= 0xDC00 && codeunit <= 0xDFFF) {
+ code_point = (code_point << 10) | (codeunit & 0x03FF);
+ code_point_ready = 1;
+ } else {
+ /* the second code unit is NOT the low surrogate. Unexpected. */
+ retval = CGPT_FAILED;
+ break;
+ }
+ }
+
+ /* If UTF code point is ready, output it. */
+ if (code_point_ready) {
+ require(code_point <= 0x10FFFF);
+ if (code_point <= 0x7F && maxoutput >= 1) {
+ maxoutput -= 1;
+ utf8[s8idx++] = code_point & 0x7F;
+ } else if (code_point <= 0x7FF && maxoutput >= 2) {
+ maxoutput -= 2;
+ utf8[s8idx++] = 0xC0 | (code_point >> 6);
+ utf8[s8idx++] = 0x80 | (code_point & 0x3F);
+ } else if (code_point <= 0xFFFF && maxoutput >= 3) {
+ maxoutput -= 3;
+ utf8[s8idx++] = 0xE0 | (code_point >> 12);
+ utf8[s8idx++] = 0x80 | ((code_point >> 6) & 0x3F);
+ utf8[s8idx++] = 0x80 | (code_point & 0x3F);
+ } else if (code_point <= 0x10FFFF && maxoutput >= 4) {
+ maxoutput -= 4;
+ utf8[s8idx++] = 0xF0 | (code_point >> 18);
+ utf8[s8idx++] = 0x80 | ((code_point >> 12) & 0x3F);
+ utf8[s8idx++] = 0x80 | ((code_point >> 6) & 0x3F);
+ utf8[s8idx++] = 0x80 | (code_point & 0x3F);
+ } else {
+ /* buffer underrun */
+ retval = CGPT_FAILED;
+ break;
+ }
+ }
}
utf8[s8idx++] = 0;
+ return retval;
}
/* Convert UTF8 string to UTF16. The UTF8 string must be null-terminated.
* Caller must prepare enough space for UTF16, including a terminating 0x0000.
- * FIXME(wfrichar): The original implementation had security issues. As a
- * temporary fix, I'm making this ONLY support ASCII codepoints. Bug 7542
- * (http://code.google.com/p/chromium-os/issues/detail?id=7542) is filed to fix
- * this.
+ * See the following table for encoding lengths. In any case, the caller
+ * just needs to prepare the byte length of UTF8 plus the terminating 0x0000.
+ *
+ * Code point UTF16 UTF8
+ * 0x0000-0x007F 2 bytes 1 byte
+ * 0x0080-0x07FF 2 bytes 2 bytes
+ * 0x0800-0xFFFF 2 bytes 3 bytes
+ * 0x10000-0x10FFFF 4 bytes 4 bytes
+ *
+ * This function converts UTF8 chars to a code point first. Then, convrts it
+ * to UTF16 code unit(s).
+ *
+ * Return: CGPT_OK --- all character are converted successfully.
+ * CGPT_FAILED --- convert error, i.e. output buffer is too short.
*/
-void UTF8ToUTF16(const uint8_t *utf8, uint16_t *utf16, unsigned int maxoutput)
+int UTF8ToUTF16(const uint8_t *utf8, uint16_t *utf16, unsigned int maxoutput)
{
size_t s16idx, s8idx;
- uint32_t utfchar;
+ uint32_t code_point = 0;
+ unsigned int expected_units = 1;
+ unsigned int decoded_units = 1;
+ int retval = CGPT_OK;
if (!utf8 || !utf16 || !maxoutput)
- return;
+ return CGPT_FAILED;
maxoutput--; /* plan for termination */
for (s8idx = s16idx = 0;
utf8[s8idx] && maxoutput;
- s8idx++, maxoutput--) {
- utfchar = utf8[s8idx];
- utf16[s16idx++] = utfchar & 0x7F;
+ s8idx++) {
+ uint8_t code_unit;
+ code_unit = utf8[s8idx];
+
+ if (expected_units != decoded_units) {
+ /* Trailing bytes of multi-byte character */
+ if ((code_unit & 0xC0) == 0x80) {
+ code_point = (code_point << 6) | (code_unit & 0x3F);
+ ++decoded_units;
+ } else {
+ /* Unexpected code unit. */
+ retval = CGPT_FAILED;
+ break;
+ }
+ } else {
+ /* parsing a new code point. */
+ decoded_units = 1;
+ if (code_unit <= 0x7F) {
+ code_point = code_unit;
+ expected_units = 1;
+ } else if (code_unit <= 0xBF) {
+ /* 0x80-0xBF must NOT be the heading byte unit of a new code point. */
+ retval = CGPT_FAILED;
+ break;
+ } else if (code_unit >= 0xC2 && code_unit <= 0xDF) {
+ code_point = code_unit & 0x1F;
+ expected_units = 2;
+ } else if (code_unit >= 0xE0 && code_unit <= 0xEF) {
+ code_point = code_unit & 0x0F;
+ expected_units = 3;
+ } else if (code_unit >= 0xF0 && code_unit <= 0xF4) {
+ code_point = code_unit & 0x07;
+ expected_units = 4;
+ } else {
+ /* illegal code unit: 0xC0-0xC1, 0xF5-0xFF */
+ retval = CGPT_FAILED;
+ break;
+ }
+ }
+
+ /* If no more unit is needed, output the UTF16 unit(s). */
+ if (expected_units == decoded_units) {
+ /* Check if the encoding is the shortest possible UTF-8 sequence. */
+ switch (expected_units) {
+ case 2:
+ if (code_point <= 0x7F) retval = CGPT_FAILED;
+ break;
+ case 3:
+ if (code_point <= 0x7FF) retval = CGPT_FAILED;
+ break;
+ case 4:
+ if (code_point <= 0xFFFF) retval = CGPT_FAILED;
+ break;
+ }
+ if (retval == CGPT_FAILED) break; /* leave immediately */
+
+ if ((code_point <= 0xD7FF) ||
+ (code_point >= 0xE000 && code_point <= 0xFFFF)) {
+ utf16[s16idx++] = code_point;
+ maxoutput -= 1;
+ } else if (code_point >= 0x10000 && code_point <= 0x10FFFF &&
+ maxoutput >= 2) {
+ utf16[s16idx++] = 0xD800 | ((code_point >> 10) - 0x0040);
+ utf16[s16idx++] = 0xDC00 | (code_point & 0x03FF);
+ maxoutput -= 2;
+ } else {
+ /* Three possibilities fall into here. Both are failure cases.
+ * a. surrogate pair (non-BMP characters; 0xD800~0xDFFF)
+ * b. invalid code point > 0x10FFFF
+ * c. buffer underrun
+ */
+ retval = CGPT_FAILED;
+ break;
+ }
+ }
}
+
+ /* A null-terminator shows up before the UTF8 sequence ends. */
+ if (expected_units != decoded_units) {
+ retval = CGPT_FAILED;
+ }
+
utf16[s16idx++] = 0;
+ return retval;
}
struct {
diff --git a/cgpt/cmd_add.c b/cgpt/cmd_add.c
index dafcc50..81b0dfa 100644
--- a/cgpt/cmd_add.c
+++ b/cgpt/cmd_add.c
@@ -251,8 +251,11 @@
if (set_unique)
memcpy(&entry->unique, &unique_guid, sizeof(Guid));
if (label) {
- UTF8ToUTF16((uint8_t *)label, entry->name,
- sizeof(entry->name) / sizeof(entry->name[0]));
+ if (CGPT_OK != UTF8ToUTF16((uint8_t *)label, entry->name,
+ sizeof(entry->name) / sizeof(entry->name[0]))) {
+ Error("The label cannot be converted to UTF16.\n");
+ goto bad;
+ }
}
if (set_raw) {
entry->attrs.fields.gpt_att = raw_value;
diff --git a/cgpt/cmd_find.c b/cgpt/cmd_find.c
index 40f10ba..43438ef 100644
--- a/cgpt/cmd_find.c
+++ b/cgpt/cmd_find.c
@@ -181,8 +181,12 @@
(set_type && !memcmp(&type_guid, &entry->type, sizeof(Guid)))) {
found = 1;
} else if (set_label) {
- UTF16ToUTF8(entry->name, sizeof(entry->name) / sizeof(entry->name[0]),
- (uint8_t *)partlabel, sizeof(partlabel));
+ if (CGPT_OK != UTF16ToUTF8(entry->name,
+ sizeof(entry->name) / sizeof(entry->name[0]),
+ (uint8_t *)partlabel, sizeof(partlabel))) {
+ Error("The label cannot be converted to UTF16, so abort.\n");
+ return 0;
+ }
if (!strncmp(label, partlabel, sizeof(partlabel))) {
found = 1;
}