+++ /dev/null
-From 4fe6744a220eddd3f1749b40cac3dfc510787de6 Mon Sep 17 00:00:00 2001
-From: Simon Kelley <simon@thekelleys.org.uk>
-Date: Fri, 19 Jan 2018 12:26:08 +0000
-Subject: [PATCH] DNSSEC fix for wildcard NSEC records. CVE-2017-15107 applies.
-
-It's OK for NSEC records to be expanded from wildcards,
-but in that case, the proof of non-existence is only valid
-starting at the wildcard name, *.<domain> NOT the name expanded
-from the wildcard. Without this check it's possible for an
-attacker to craft an NSEC which wrongly proves non-existence
-in a domain which includes a wildcard for NSEC.
-
-[baruch: drop the CHANGELOG hunk]
-Signed-off-by: Baruch Siach <baruch@tkos.co.il>
----
-Upstream status: upstream commit 4fe6744a220e
-
- CHANGELOG | 12 +++++-
- src/dnssec.c | 117 ++++++++++++++++++++++++++++++++++++++++++++++++++++-------
- 2 files changed, 114 insertions(+), 15 deletions(-)
-
-diff --git a/src/dnssec.c b/src/dnssec.c
-index eb6c11cbe00f..a54a0b4f14cf 100644
---- a/src/dnssec.c
-+++ b/src/dnssec.c
-@@ -103,15 +103,17 @@ static void from_wire(char *name)
- static int count_labels(char *name)
- {
- int i;
--
-+ char *p;
-+
- if (*name == 0)
- return 0;
-
-- for (i = 0; *name; name++)
-- if (*name == '.')
-+ for (p = name, i = 0; *p; p++)
-+ if (*p == '.')
- i++;
-
-- return i+1;
-+ /* Don't count empty first label. */
-+ return *name == '.' ? i : i+1;
- }
-
- /* Implement RFC1982 wrapped compare for 32-bit numbers */
-@@ -1094,8 +1096,8 @@ static int hostname_cmp(const char *a, const char *b)
- }
- }
-
--static int prove_non_existence_nsec(struct dns_header *header, size_t plen, unsigned char **nsecs, int nsec_count,
-- char *workspace1, char *workspace2, char *name, int type, int *nons)
-+static int prove_non_existence_nsec(struct dns_header *header, size_t plen, unsigned char **nsecs, unsigned char **labels, int nsec_count,
-+ char *workspace1_in, char *workspace2, char *name, int type, int *nons)
- {
- int i, rc, rdlen;
- unsigned char *p, *psave;
-@@ -1108,6 +1110,9 @@ static int prove_non_existence_nsec(struct dns_header *header, size_t plen, unsi
- /* Find NSEC record that proves name doesn't exist */
- for (i = 0; i < nsec_count; i++)
- {
-+ char *workspace1 = workspace1_in;
-+ int sig_labels, name_labels;
-+
- p = nsecs[i];
- if (!extract_name(header, plen, &p, workspace1, 1, 10))
- return 0;
-@@ -1116,7 +1121,27 @@ static int prove_non_existence_nsec(struct dns_header *header, size_t plen, unsi
- psave = p;
- if (!extract_name(header, plen, &p, workspace2, 1, 10))
- return 0;
--
-+
-+ /* If NSEC comes from wildcard expansion, use original wildcard
-+ as name for computation. */
-+ sig_labels = *labels[i];
-+ name_labels = count_labels(workspace1);
-+
-+ if (sig_labels < name_labels)
-+ {
-+ int k;
-+ for (k = name_labels - sig_labels; k != 0; k--)
-+ {
-+ while (*workspace1 != '.' && *workspace1 != 0)
-+ workspace1++;
-+ if (k != 1 && *workspace1 == '.')
-+ workspace1++;
-+ }
-+
-+ workspace1--;
-+ *workspace1 = '*';
-+ }
-+
- rc = hostname_cmp(workspace1, name);
-
- if (rc == 0)
-@@ -1514,24 +1539,26 @@ static int prove_non_existence_nsec3(struct dns_header *header, size_t plen, uns
-
- static int prove_non_existence(struct dns_header *header, size_t plen, char *keyname, char *name, int qtype, int qclass, char *wildname, int *nons)
- {
-- static unsigned char **nsecset = NULL;
-- static int nsecset_sz = 0;
-+ static unsigned char **nsecset = NULL, **rrsig_labels = NULL;
-+ static int nsecset_sz = 0, rrsig_labels_sz = 0;
-
- int type_found = 0;
-- unsigned char *p = skip_questions(header, plen);
-+ unsigned char *auth_start, *p = skip_questions(header, plen);
- int type, class, rdlen, i, nsecs_found;
-
- /* Move to NS section */
- if (!p || !(p = skip_section(p, ntohs(header->ancount), header, plen)))
- return 0;
-+
-+ auth_start = p;
-
- for (nsecs_found = 0, i = ntohs(header->nscount); i != 0; i--)
- {
- unsigned char *pstart = p;
-
-- if (!(p = skip_name(p, header, plen, 10)))
-+ if (!extract_name(header, plen, &p, daemon->workspacename, 1, 10))
- return 0;
--
-+
- GETSHORT(type, p);
- GETSHORT(class, p);
- p += 4; /* TTL */
-@@ -1548,7 +1575,69 @@ static int prove_non_existence(struct dns_header *header, size_t plen, char *key
- if (!expand_workspace(&nsecset, &nsecset_sz, nsecs_found))
- return 0;
-
-- nsecset[nsecs_found++] = pstart;
-+ if (type == T_NSEC)
-+ {
-+ /* If we're looking for NSECs, find the corresponding SIGs, to
-+ extract the labels value, which we need in case the NSECs
-+ are the result of wildcard expansion.
-+ Note that the NSEC may not have been validated yet
-+ so if there are multiple SIGs, make sure the label value
-+ is the same in all, to avoid be duped by a rogue one.
-+ If there are no SIGs, that's an error */
-+ unsigned char *p1 = auth_start;
-+ int res, j, rdlen1, type1, class1;
-+
-+ if (!expand_workspace(&rrsig_labels, &rrsig_labels_sz, nsecs_found))
-+ return 0;
-+
-+ rrsig_labels[nsecs_found] = NULL;
-+
-+ for (j = ntohs(header->nscount); j != 0; j--)
-+ {
-+ if (!(res = extract_name(header, plen, &p1, daemon->workspacename, 0, 10)))
-+ return 0;
-+
-+ GETSHORT(type1, p1);
-+ GETSHORT(class1, p1);
-+ p1 += 4; /* TTL */
-+ GETSHORT(rdlen1, p1);
-+
-+ if (!CHECK_LEN(header, p1, plen, rdlen1))
-+ return 0;
-+
-+ if (res == 1 && class1 == qclass && type1 == T_RRSIG)
-+ {
-+ int type_covered;
-+ unsigned char *psav = p1;
-+
-+ if (rdlen < 18)
-+ return 0; /* bad packet */
-+
-+ GETSHORT(type_covered, p1);
-+
-+ if (type_covered == T_NSEC)
-+ {
-+ p1++; /* algo */
-+
-+ /* labels field must be the same in every SIG we find. */
-+ if (!rrsig_labels[nsecs_found])
-+ rrsig_labels[nsecs_found] = p1;
-+ else if (*rrsig_labels[nsecs_found] != *p1) /* algo */
-+ return 0;
-+ }
-+ p1 = psav;
-+ }
-+
-+ if (!ADD_RDLEN(header, p1, plen, rdlen1))
-+ return 0;
-+ }
-+
-+ /* Must have found at least one sig. */
-+ if (!rrsig_labels[nsecs_found])
-+ return 0;
-+ }
-+
-+ nsecset[nsecs_found++] = pstart;
- }
-
- if (!ADD_RDLEN(header, p, plen, rdlen))
-@@ -1556,7 +1645,7 @@ static int prove_non_existence(struct dns_header *header, size_t plen, char *key
- }
-
- if (type_found == T_NSEC)
-- return prove_non_existence_nsec(header, plen, nsecset, nsecs_found, daemon->workspacename, keyname, name, qtype, nons);
-+ return prove_non_existence_nsec(header, plen, nsecset, rrsig_labels, nsecs_found, daemon->workspacename, keyname, name, qtype, nons);
- else if (type_found == T_NSEC3)
- return prove_non_existence_nsec3(header, plen, nsecset, nsecs_found, daemon->workspacename, keyname, name, qtype, wildname, nons);
- else
---
-2.15.1
-
projects / coffee / buildroot.git / commitdiff