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krb5: Fix DNS SRV name collision handling

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This commit is contained in:
Nicolas Williams
2024-01-09 21:09:33 -06:00
committed by Jeffrey Altman
parent 8d20888e09
commit 305ab03155
1 changed files with 23 additions and 16 deletions
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39
lib/krb5/krbhst.c
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@@ -49,12 +49,22 @@ string_to_proto(const char *string)
return -1;
}
#define YOUR_DNS_NEEDS_IMM_ATTENTION "your-dns-needs-immediate-attention."
static int
is_invalid_tld_srv_target(const char *target)
{
return (strncmp("your-dns-needs-immediate-attention.",
target, 35) == 0
&& strchr(&target[35], '.') == NULL);
if (strncmp(YOUR_DNS_NEEDS_IMM_ATTENTION, target,
sizeof(YOUR_DNS_NEEDS_IMM_ATTENTION) - 1) != 0)
return 0;
target += sizeof(YOUR_DNS_NEEDS_IMM_ATTENTION) - 1;
if (target[0] == '\0' || target[0] == '.')
return 0; /* malformed; should be followed by a TLD */
target = strchr(target, '.');
if (target == NULL)
return 0; /* malformed; should end in a '.' */
if (target[1] != '\0')
return 0; /* malformed; should be followed by just one label (the TLD) */
return 1;
}
/*
@@ -129,28 +139,25 @@ srv_find_realm(krb5_context context, krb5_krbhst_info ***res, int *count,
if(rr->type == rk_ns_t_srv) {
krb5_krbhst_info *hi = NULL;
size_t len;
int invalid_tld = 1;
/* Test for top-level domain controlled interruptions */
if (!is_invalid_tld_srv_target(rr->u.srv->target)) {
invalid_tld = 0;
len = strlen(rr->u.srv->target);
hi = calloc(1, sizeof(*hi) + len);
if (is_invalid_tld_srv_target(rr->u.srv->target)) {
krb5_warnx(context,
"Domain lookup failed: "
"Realm %s needs immediate attention "
"see https://icann.org/namecollision",
realm);
return KRB5_KDC_UNREACH;
}
len = strlen(rr->u.srv->target);
hi = calloc(1, sizeof(*hi) + len);
if(hi == NULL) {
rk_dns_free_data(r);
while(--num_srv >= 0)
free((*res)[num_srv]);
free(*res);
*res = NULL;
if (invalid_tld) {
krb5_warnx(context,
"Domain lookup failed: "
"Realm %s needs immediate attention "
"see https://icann.org/namecollision",
realm);
return KRB5_KDC_UNREACH;
}
return krb5_enomem(context);
}
(*res)[num_srv++] = hi;