be triggered by externally-controlled input. Found by Trend Micro.
CVE-2023-42114
+JH/43 Bug 2903: avoid exit on an attempt to rewrite a malformed address.
+ Make the rewrite never match and keep the logging. Trust the
+ admin to be using verify=header-syntax (to actually reject the message).
+
+JH/44 Bug 3033: Harden dnsdb lookups against crafted DNS responses.
+ CVE-2023-42219
+
+HS/02 Fix string_is_ip_address() CVE-2023-42117 (Bug 3031)
Exim version 4.96
-----------------
static BOOL
dnss_inc_aptr(const dns_answer * dnsa, dns_scan * dnss, unsigned delta)
{
-return (dnss->aptr += delta) >= dnsa->answer + dnsa->answerlen;
+return (dnss->aptr += delta) > dnsa->answer + dnsa->answerlen;
}
/*************************************************
TRACE trace = "A-hdr";
if (dnss_inc_aptr(dnsa, dnss, namelen+8)) goto null_return;
GETSHORT(dnss->srr.size, dnss->aptr); /* size of data portion */
- /* skip over it */
+ /* skip over it, checking for a bogus size */
TRACE trace = "A-skip";
if (dnss_inc_aptr(dnsa, dnss, dnss->srr.size)) goto null_return;
}
GETSHORT(dnss->srr.size, dnss->aptr); /* Size of data portion */
dnss->srr.data = dnss->aptr; /* The record's data follows */
-/* Unchecked increment ok here since no further access on this iteration;
-will be checked on next at "R-name". */
-
-dnss->aptr += dnss->srr.size; /* Advance to next RR */
+/* skip over it, checking for a bogus size */
+if (dnss_inc_aptr(dnsa, dnss, dnss->srr.size))
+ goto null_return;
/* Return a pointer to the dns_record structure within the dns_answer. This is
for convenience so that the scans can use nice-looking for loops. */
case ECOND_ISIP:
case ECOND_ISIP4:
case ECOND_ISIP6:
- rc = string_is_ip_address(sub[0], NULL);
- *yield = ((cond_type == ECOND_ISIP)? (rc != 0) :
- (cond_type == ECOND_ISIP4)? (rc == 4) : (rc == 6)) == testfor;
+ {
+ const uschar *errp;
+ const uschar **errpp;
+ DEBUG(D_expand) errpp = &errp; else errpp = 0;
+ if (0 == (rc = string_is_ip_addressX(sub[0], NULL, errpp)))
+ DEBUG(D_expand) debug_printf("failed: %s\n", errp);
+
+ *yield = ( cond_type == ECOND_ISIP ? rc != 0 :
+ cond_type == ECOND_ISIP4 ? rc == 4 : rc == 6) == testfor;
+ }
+
break;
/* Various authentication tests - all optionally compiled */
extern uschar *string_format_size(int, uschar *);
extern int string_interpret_escape(const uschar **);
extern int string_is_ip_address(const uschar *, int *);
+extern int string_is_ip_addressX(const uschar *, int *, const uschar **);
#ifdef SUPPORT_I18N
extern BOOL string_is_utf8(const uschar *);
#endif
if (type == T_TXT || type == T_SPF)
{
if (!outsep2) /* output only the first item of data */
- yield = string_catn(yield, US (rr->data+1), (rr->data)[0]);
+ {
+ uschar n = (rr->data)[0];
+ /* size byte + data bytes must not excced the RRs length */
+ if (n + 1 <= rr->size)
+ yield = string_catn(yield, US (rr->data+1), n);
+ }
else
for (unsigned data_offset = 0; data_offset < rr->size; )
{
uschar chunk_len = (rr->data)[data_offset];
+ int remain = rr->size - data_offset;
+
+ /* Apparently there are resolvers that do not check RRs before passing
+ them on, and glibc fails to do so. So every application must...
+ Check for chunk len exceeding RR */
+
+ if (chunk_len > remain)
+ chunk_len = remain;
+
if (*outsep2 && data_offset != 0)
yield = string_catn(yield, outsep2, 1);
- yield = string_catn(yield, US ((rr->data) + ++data_offset), chunk_len);
+ yield = string_catn(yield, US ((rr->data) + ++data_offset), --chunk_len);
data_offset += chunk_len;
}
}
else if (type == T_TLSA)
- {
- uint8_t usage, selector, matching_type;
- uint16_t payload_length;
- uschar s[MAX_TLSA_EXPANDED_SIZE];
- uschar * sp = s;
- uschar * p = US rr->data;
+ if (rr->size < 3)
+ continue;
+ else
+ {
+ uint8_t usage, selector, matching_type;
+ uint16_t payload_length;
+ uschar s[MAX_TLSA_EXPANDED_SIZE];
+ uschar * sp = s;
+ uschar * p = US rr->data;
+
+ usage = *p++;
+ selector = *p++;
+ matching_type = *p++;
+ /* What's left after removing the first 3 bytes above */
+ payload_length = rr->size - 3;
+ sp += sprintf(CS s, "%d%c%d%c%d%c", usage, *outsep2,
+ selector, *outsep2, matching_type, *outsep2);
+ /* Now append the cert/identifier, one hex char at a time */
+ while (payload_length-- > 0 && sp-s < (MAX_TLSA_EXPANDED_SIZE - 4))
+ sp += sprintf(CS sp, "%02x", *p++);
- usage = *p++;
- selector = *p++;
- matching_type = *p++;
- /* What's left after removing the first 3 bytes above */
- payload_length = rr->size - 3;
- sp += sprintf(CS s, "%d%c%d%c%d%c", usage, *outsep2,
- selector, *outsep2, matching_type, *outsep2);
- /* Now append the cert/identifier, one hex char at a time */
- while (payload_length-- > 0 && sp-s < (MAX_TLSA_EXPANDED_SIZE - 4))
- sp += sprintf(CS sp, "%02x", *p++);
-
- yield = string_cat(yield, s);
- }
+ yield = string_cat(yield, s);
+ }
else /* T_CNAME, T_CSA, T_MX, T_MXH, T_NS, T_PTR, T_SOA, T_SRV */
{
int priority, weight, port;
switch (type)
{
case T_MXH:
+ if (rr->size < sizeof(u_int16_t)) continue;
/* mxh ignores the priority number and includes only the hostnames */
GETSHORT(priority, p);
break;
case T_MX:
+ if (rr->size < sizeof(u_int16_t)) continue;
GETSHORT(priority, p);
sprintf(CS s, "%d%c", priority, *outsep2);
yield = string_cat(yield, s);
break;
case T_SRV:
+ if (rr->size < 3*sizeof(u_int16_t)) continue;
GETSHORT(priority, p);
GETSHORT(weight, p);
GETSHORT(port, p);
break;
case T_CSA:
+ if (rr->size < 3*sizeof(u_int16_t)) continue;
/* See acl_verify_csa() for more comments about CSA. */
GETSHORT(priority, p);
GETSHORT(weight, p);
if (type == T_SOA && outsep2 != NULL)
{
- unsigned long serial, refresh, retry, expire, minimum;
+ unsigned long serial = 0, refresh = 0, retry = 0, expire = 0, minimum = 0;
p += rc;
yield = string_catn(yield, outsep2, 1);
else yield = string_cat(yield, s);
p += rc;
- GETLONG(serial, p); GETLONG(refresh, p);
- GETLONG(retry, p); GETLONG(expire, p); GETLONG(minimum, p);
+ if (rr->size >= p - rr->data - 5*sizeof(u_int32_t))
+ {
+ GETLONG(serial, p); GETLONG(refresh, p);
+ GETLONG(retry, p); GETLONG(expire, p); GETLONG(minimum, p);
+ }
sprintf(CS s, "%c%lu%c%lu%c%lu%c%lu%c%lu",
*outsep2, serial, *outsep2, refresh,
*outsep2, retry, *outsep2, expire, *outsep2, minimum);
maskptr NULL if no mask is permitted to follow
otherwise, points to an int where the offset of '/' is placed
if there is no / followed by trailing digits, *maskptr is set 0
+ errp NULL if no diagnostic information is required, and if the netmask
+ length should not be checked. Otherwise it is set pointing to a short
+ descriptive text.
Returns: 0 if the string is not a textual representation of an IP address
4 if it is an IPv4 address
6 if it is an IPv6 address
-*/
+The legacy string_is_ip_address() function follows below.
+*/
int
-string_is_ip_address(const uschar *s, int *maskptr)
-{
-int yield = 4;
+string_is_ip_addressX(const uschar *ip_addr, int *maskptr, const uschar **errp) {
+ struct addrinfo hints;
+ struct addrinfo *res;
-/* If an optional mask is permitted, check for it. If found, pass back the
-offset. */
+ uschar *slash, *percent;
-if (maskptr)
+ uschar *endp = 0;
+ long int mask = 0;
+ const uschar *addr = 0;
+
+ /* If there is a slash, but we didn't request a (optional) netmask,
+ we return failure, as we do if the mask isn't a pure numerical value,
+ or if it is negative. The actual length is checked later, once we know
+ the address family. */
+ if (slash = Ustrchr(ip_addr, '/'))
{
- const uschar *ss = s + Ustrlen(s);
- *maskptr = 0;
- if (s != ss && isdigit(*(--ss)))
+ if (!maskptr)
{
- while (ss > s && isdigit(ss[-1])) ss--;
- if (ss > s && *(--ss) == '/') *maskptr = ss - s;
+ if (errp) *errp = "netmask found, but not requested";
+ return 0;
}
- }
-
-/* A colon anywhere in the string => IPv6 address */
-
-if (Ustrchr(s, ':') != NULL)
- {
- BOOL had_double_colon = FALSE;
- BOOL v4end = FALSE;
-
- yield = 6;
-
- /* An IPv6 address must start with hex digit or double colon. A single
- colon is invalid. */
-
- if (*s == ':' && *(++s) != ':') return 0;
-
- /* Now read up to 8 components consisting of up to 4 hex digits each. There
- may be one and only one appearance of double colon, which implies any number
- of binary zero bits. The number of preceding components is held in count. */
- for (int count = 0; count < 8; count++)
+ uschar *rest;
+ mask = Ustrtol(slash+1, &rest, 10);
+ if (*rest || mask < 0)
{
- /* If the end of the string is reached before reading 8 components, the
- address is valid provided a double colon has been read. This also applies
- if we hit the / that introduces a mask or the % that introduces the
- interface specifier (scope id) of a link-local address. */
-
- if (*s == 0 || *s == '%' || *s == '/') return had_double_colon ? yield : 0;
-
- /* If a component starts with an additional colon, we have hit a double
- colon. This is permitted to appear once only, and counts as at least
- one component. The final component may be of this form. */
-
- if (*s == ':')
- {
- if (had_double_colon) return 0;
- had_double_colon = TRUE;
- s++;
- continue;
- }
-
- /* If the remainder of the string contains a dot but no colons, we
- can expect a trailing IPv4 address. This is valid if either there has
- been no double-colon and this is the 7th component (with the IPv4 address
- being the 7th & 8th components), OR if there has been a double-colon
- and fewer than 6 components. */
-
- if (Ustrchr(s, ':') == NULL && Ustrchr(s, '.') != NULL)
- {
- if ((!had_double_colon && count != 6) ||
- (had_double_colon && count > 6)) return 0;
- v4end = TRUE;
- yield = 6;
- break;
- }
-
- /* Check for at least one and not more than 4 hex digits for this
- component. */
-
- if (!isxdigit(*s++)) return 0;
- if (isxdigit(*s) && isxdigit(*(++s)) && isxdigit(*(++s))) s++;
-
- /* If the component is terminated by colon and there is more to
- follow, skip over the colon. If there is no more to follow the address is
- invalid. */
-
- if (*s == ':' && *(++s) == 0) return 0;
+ if (errp) *errp = "netmask not numeric or <0";
+ return 0;
}
- /* If about to handle a trailing IPv4 address, drop through. Otherwise
- all is well if we are at the end of the string or at the mask or at a percent
- sign, which introduces the interface specifier (scope id) of a link local
- address. */
+ *maskptr = slash - ip_addr; /* offset of the slash */
+ endp = slash;
+ } else if (maskptr) *maskptr = 0; /* no slash found */
- if (!v4end)
- return (*s == 0 || *s == '%' ||
- (*s == '/' && maskptr != NULL && *maskptr != 0))? yield : 0;
+ /* The interface-ID suffix (%<id>) is optional (for IPv6). If it
+ exists, we check it syntactically. Later, if we know the address
+ family is IPv4, we might reject it.
+ The interface-ID is mutually exclusive with the netmask, to the
+ best of my knowledge. */
+ if (percent = Ustrchr(ip_addr, '%'))
+ {
+ if (slash)
+ {
+ if (errp) *errp = "interface-ID and netmask are mutually exclusive";
+ return 0;
+ }
+ for (uschar *p = percent+1; *p; p++)
+ if (!isalnum(*p) && !ispunct(*p))
+ {
+ if (errp) *errp = "interface-ID must match [[:alnum:][:punct:]]";
+ return 0;
+ }
+ endp = percent;
}
-/* Test for IPv4 address, which may be the tail-end of an IPv6 address. */
-
-for (int i = 0; i < 4; i++)
+ /* inet_pton() can't parse netmasks and interface IDs, so work on a shortened copy
+ allocated on the current stack */
+ if (endp) {
+ ptrdiff_t l = endp - ip_addr;
+ if (l > 255)
+ {
+ if (errp) *errp = "rudiculous long ip address string";
+ return 0;
+ }
+ addr = alloca(l+1); /* *BSD does not have strndupa() */
+ Ustrncpy((uschar *)addr, ip_addr, l);
+ ((uschar*)addr)[l] = '\0';
+ } else addr = ip_addr;
+
+ int af;
+ union { /* we do not need this, but inet_pton() needs a place for storage */
+ struct in_addr sa4;
+ struct in6_addr sa6;
+ } sa;
+
+ af = Ustrchr(addr, ':') ? AF_INET6 : AF_INET;
+ if (!inet_pton(af, addr, &sa))
{
- long n;
- uschar * end;
-
- if (i != 0 && *s++ != '.') return 0;
- n = strtol(CCS s, CSS &end, 10);
- if (n > 255 || n < 0 || end <= s || end > s+3) return 0;
- s = end;
+ if (errp) *errp = af == AF_INET6 ? "IP address string not parsable as IPv6"
+ : "IP address string not parsable IPv4";
+ return 0;
}
+ /* we do not check the values of the mask here, as
+ this is done on the callers side (but I don't understand why), so
+ actually I'd like to do it here, but it breaks at least 0002 */
+ switch (af)
+ {
+ case AF_INET6:
+ if (errp && mask > 128)
+ {
+ *errp = "IPv6 netmask value must not be >128";
+ return 0;
+ }
+ return 6;
+ case AF_INET:
+ if (percent)
+ {
+ if (errp) *errp = "IPv4 address string must not have an interface-ID";
+ return 0;
+ }
+ if (errp && mask > 32) {
+ *errp = "IPv4 netmask value must not be >32";
+ return 0;
+ }
+ return 4;
+ default:
+ if (errp) *errp = "unknown address family (should not happen)";
+ return 0;
+ }
+}
-return !*s || (*s == '/' && maskptr && *maskptr != 0) ? yield : 0;
+int
+string_is_ip_address(const uschar *ip_addr, int *maskptr) {
+ return string_is_ip_addressX(ip_addr, maskptr, 0);
}
+
#endif /* COMPILE_UTILITY */
gei: ${if gei{ABC}{abc}{y}{n}}
isip: ${if isip {1.2.3.4}{y}{n}} 1.2.3.4
+isip: ${if isip {1.2.3}{y}{n}} 1.2.3
isip4: ${if isip4{1.2.3.4}{y}{n}} 1.2.3.4
isip6: ${if isip6{1.2.3.4}{y}{n}} 1.2.3.4
isip: ${if isip {::1.2.3.256}{y}{n}} ::1.2.3.256
isip: ${if isip {rhubarb}{y}{n}} rhubarb
isip4: ${if isip4{rhubarb}{y}{n}} rhubarb
isip6: ${if isip6{rhubarb}{y}{n}} rhubarb
+isip6: ${if isip6{::/100}{y}{n}} ::/100
+isip6: ${if isip6{::/foo}{y}{n}} ::/foo
+isip6: ${if isip6{::/f o}{y}{n}} ::/f o
match: ${if match{abcd}{\N^([ab]+)(\w+)$\N}{$2$1}fail}
match: ${if match{abcd}{^\N([ab]+)(\w+)$\N}{$2$1}fail}
> gei: y
>
> isip: y 1.2.3.4
+> isip: n 1.2.3
> isip4: y 1.2.3.4
> isip6: n 1.2.3.4
> isip: n ::1.2.3.256
> isip: n rhubarb
> isip4: n rhubarb
> isip6: n rhubarb
+> isip6: n ::/100
+> isip6: n ::/foo
+> isip6: n ::/f o
>
> match: cdab
> match: cdab
git://git.exim.org / exim.git / commitdiff