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Actually use tor_sscanf() to parse untrusted input.

Browse source 
svn:r18761
This commit is contained in:
Nick Mathewson 2009-03-03 18:02:36 +00:00
parent 26d83fc04c
commit cbbc0c9c86
5 changed files with 64 additions and 40 deletions
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2
ChangeLog
View file

@ -39,6 +39,8 @@ Changes in version 0.2.1.13-????? - 2009-02-??
- Do not assume that a stack-allocated character array will be
64-bit aligned on platforms that demand that uint64_t access is
aligned. Possible fix for bug 604.
- Parse dates and IPv4 addresses in a locale- and libc-independent
manner, to avoid platform-dependent behavior on malformed input.
o Minor features:
- On Linux, use the prctl call to re-enable core dumps when the user

22
src/common/compat.c
View file

@ -1296,14 +1296,14 @@ get_user_homedir(const char *username)
int
tor_inet_aton(const char *str, struct in_addr* addr)
{
int a,b,c,d;
unsigned a,b,c,d;
char more;
if (sscanf(str, "%d.%d.%d.%d%c", &a,&b,&c,&d,&more) != 4)
if (tor_sscanf(str, "%3u.%3u.%3u.%3u%c", &a,&b,&c,&d,&more) != 4)
return 0;
if (a < 0 || a > 255) return 0;
if (b < 0 || b > 255) return 0;
if (c < 0 || c > 255) return 0;
if (d < 0 || d > 255) return 0;
if (a > 255) return 0;
if (b > 255) return 0;
if (c > 255) return 0;
if (d > 255) return 0;
addr->s_addr = htonl((a<<24) | (b<<16) | (c<<8) | d);
return 1;
}
@ -1421,7 +1421,7 @@ tor_inet_pton(int af, const char *src, void *dst)
else if (!dot)
eow = src+strlen(src);
else {
int byte1,byte2,byte3,byte4;
unsigned byte1,byte2,byte3,byte4;
char more;
for (eow = dot-1; eow >= src && TOR_ISDIGIT(*eow); --eow)
;
@ -1429,13 +1429,11 @@ tor_inet_pton(int af, const char *src, void *dst)
/* We use "scanf" because some platform inet_aton()s are too lax
* about IPv4 addresses of the form "1.2.3" */
if (sscanf(eow, "%d.%d.%d.%d%c", &byte1,&byte2,&byte3,&byte4,&more) != 4)
if (tor_sscanf(eow, "%3u.%3u.%3u.%3u%c",
&byte1,&byte2,&byte3,&byte4,&more) != 4)
return 0;
if (byte1 > 255 || byte1 < 0 ||
byte2 > 255 || byte2 < 0 ||
byte3 > 255 || byte3 < 0 ||
byte4 > 255 || byte4 < 0)
if (byte1 > 255 || byte2 > 255 || byte3 > 255 || byte4 > 255)
return 0;
words[6] = (byte1<<8) | byte2;

71
src/common/util.c
View file

@ -1095,18 +1095,30 @@ parse_rfc1123_time(const char *buf, time_t *t)
char month[4];
char weekday[4];
int i, m;
unsigned tm_mday, tm_year, tm_hour, tm_min, tm_sec;
if (strlen(buf) != RFC1123_TIME_LEN)
return -1;
memset(&tm, 0, sizeof(tm));
if (sscanf(buf, "%3s, %d %3s %d %d:%d:%d GMT", weekday,
&tm.tm_mday, month, &tm.tm_year, &tm.tm_hour,
&tm.tm_min, &tm.tm_sec) < 7) {
if (tor_sscanf(buf, "%3s, %2u %3s %u %2u:%2u:%2u GMT", weekday,
&tm_mday, month, &tm_year, &tm_hour,
&tm_min, &tm_sec) < 7) {
char *esc = esc_for_log(buf);
log_warn(LD_GENERAL, "Got invalid RFC1123 time %s", esc);
tor_free(esc);
return -1;
}
if (tm_mday > 31 || tm_hour > 23 || tm_min > 59 || tm_sec > 61) {
char *esc = esc_for_log(buf);
log_warn(LD_GENERAL, "Got invalid RFC1123 time %s", esc);
tor_free(esc);
return -1;
}
tm.tm_mday = (int)tm_mday;
tm.tm_year = (int)tm_year;
tm.tm_hour = (int)tm_hour;
tm.tm_min = (int)tm_min;
tm.tm_sec = (int)tm_sec;
m = -1;
for (i = 0; i < 12; ++i) {
@ -1166,19 +1178,20 @@ int
parse_iso_time(const char *cp, time_t *t)
{
struct tm st_tm;
#ifdef HAVE_STRPTIME
if (!strptime(cp, "%Y-%m-%d %H:%M:%S", &st_tm)) {
log_warn(LD_GENERAL, "ISO time was unparseable by strptime"); return -1;
}
#else
unsigned int year=0, month=0, day=0, hour=100, minute=100, second=100;
if (sscanf(cp, "%u-%u-%u %u:%u:%u", &year, &month,
if (tor_sscanf(cp, "%u-%2u-%2u %2u:%2u:%2u", &year, &month,
&day, &hour, &minute, &second) < 6) {
log_warn(LD_GENERAL, "ISO time was unparseable"); return -1;
char *esc = esc_for_log(cp);
log_warn(LD_GENERAL, "ISO time %s was unparseable", esc);
tor_free(esc);
return -1;
}
if (year < 1970 || month < 1 || month > 12 || day < 1 || day > 31 ||
hour > 23 || minute > 59 || second > 61) {
log_warn(LD_GENERAL, "ISO time was nonsensical"); return -1;
char *esc = esc_for_log(cp);
log_warn(LD_GENERAL, "ISO time %s was nonsensical", esc);
tor_free(esc);
return -1;
}
st_tm.tm_year = year-1900;
st_tm.tm_mon = month-1;
@ -1186,7 +1199,7 @@ parse_iso_time(const char *cp, time_t *t)
st_tm.tm_hour = hour;
st_tm.tm_min = minute;
st_tm.tm_sec = second;
#endif
if (st_tm.tm_year < 70) {
char *esc = esc_for_log(cp);
log_warn(LD_GENERAL, "Got invalid ISO time %s. (Before 1970)", esc);
@ -1206,6 +1219,7 @@ parse_http_time(const char *date, struct tm *tm)
char month[4];
char wkday[4];
int i;
unsigned tm_mday, tm_year, tm_hour, tm_min, tm_sec;
tor_assert(tm);
memset(tm, 0, sizeof(*tm));
@ -1213,28 +1227,33 @@ parse_http_time(const char *date, struct tm *tm)
/* First, try RFC1123 or RFC850 format: skip the weekday. */
if ((cp = strchr(date, ','))) {
++cp;
if (sscanf(date, "%2d %3s %4d %2d:%2d:%2d GMT",
&tm->tm_mday, month, &tm->tm_year,
&tm->tm_hour, &tm->tm_min, &tm->tm_sec) == 6) {
if (tor_sscanf(date, "%2u %3s %4u %2u:%2u:%2u GMT",
&tm_mday, month, &tm_year,
&tm_hour, &tm_min, &tm_sec) == 6) {
/* rfc1123-date */
tm->tm_year -= 1900;
} else if (sscanf(date, "%2d-%3s-%2d %2d:%2d:%2d GMT",
&tm->tm_mday, month, &tm->tm_year,
&tm->tm_hour, &tm->tm_min, &tm->tm_sec) == 6) {
tm_year -= 1900;
} else if (tor_sscanf(date, "%2u-%3s-%2u %2u:%2u:%2u GMT",
&tm_mday, month, &tm_year,
&tm_hour, &tm_min, &tm_sec) == 6) {
/* rfc850-date */
} else {
return -1;
}
} else {
/* No comma; possibly asctime() format. */
if (sscanf(date, "%3s %3s %2d %2d:%2d:%2d %4d",
wkday, month, &tm->tm_mday,
&tm->tm_hour, &tm->tm_min, &tm->tm_sec, &tm->tm_year) == 7) {
tm->tm_year -= 1900;
if (tor_sscanf(date, "%3s %3s %2u %2u:%2u:%2u %4u",
wkday, month, &tm_mday,
&tm_hour, &tm_min, &tm_sec, &tm_year) == 7) {
tm_year -= 1900;
} else {
return -1;
}
}
tm->tm_mday = (int)tm_mday;
tm->tm_year = (int)tm_year;
tm->tm_hour = (int)tm_hour;
tm->tm_min = (int)tm_min;
tm->tm_sec = (int)tm_sec;
month[3] = '\0';
/* Okay, now decode the month. */
@ -2202,7 +2221,7 @@ scan_unsigned(const char **bufp, unsigned *out, int width)
{
unsigned result = 0;
int scanned_so_far = 0;
if (!bufp || !*bufp)
if (!bufp || !*bufp || !out)
return -1;
if (width<0)
width=MAX_SCANF_WIDTH;
@ -2228,7 +2247,7 @@ static int
scan_string(const char **bufp, char *out, int width)
{
int scanned_so_far = 0;
if (!bufp || width < 0)
if (!bufp || !out || width < 0)
return -1;
while (**bufp && ! TOR_ISSPACE(**bufp) && scanned_so_far < width) {
*out++ = *(*bufp)++;
@ -2312,7 +2331,7 @@ tor_vsscanf(const char *buf, const char *pattern, va_list ap)
* and store the results in the corresponding argument fields. Differs from
* sscanf in that it: Only handles %u and %Ns. Does not handle arbitrarily
* long widths. %u does not consume any space. Is locale-independent.
* Returns -1 on malformed */
* Returns -1 on malformed patterns. */
int
tor_sscanf(const char *buf, const char *pattern, ...)
{

4
src/or/directory.c
View file

@ -1247,7 +1247,7 @@ int
parse_http_response(const char *headers, int *code, time_t *date,
compress_method_t *compression, char **reason)
{
int n1, n2;
unsigned n1, n2;
char datestr[RFC1123_TIME_LEN+1];
smartlist_t *parsed_headers;
tor_assert(headers);
@ -1255,7 +1255,7 @@ parse_http_response(const char *headers, int *code, time_t *date,
while (TOR_ISSPACE(*headers)) headers++; /* tolerate leading whitespace */
if (sscanf(headers, "HTTP/1.%d %d", &n1, &n2) < 2 ||
if (tor_sscanf(headers, "HTTP/1.%u %u", &n1, &n2) < 2 ||
(n1 != 0 && n1 != 1) ||
(n2 < 100 || n2 >= 600)) {
log_warn(LD_HTTP,"Failed to parse header %s",escaped(headers));

5
src/or/test.c
View file

@ -2796,6 +2796,11 @@ test_util_sscanf(void)
test_eq(u1, 12u);
test_eq(u2, 3u);
test_eq(u3, 99u);
r = tor_sscanf("99% fresh", "%3u%% fresh", &u1); /* percents are scannable.*/
test_eq(r, 1);
test_eq(u1, 99);
r = tor_sscanf("hello", "%s", s1); /* %s needs a number. */
test_eq(r, -1);