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Merge branch '4475-use-atomics-to-access-trust-access-in-dns_ncache' into 'main'

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Use atomic operations to access the trust byte in ncache data

Closes #4475

See merge request isc-projects/bind9!8946
This commit is contained in:
Ondřej Surý
2024-04-17 19:18:35 +00:00
parent 90b0038ea0 d2fd97f4da
commit fcf2919c93
3 changed files with 28 additions and 12 deletions
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3
CHANGES
View File

@@ -1,3 +1,6 @@
6371. [bug] Access to the trust bytes in the ncache data needed to
be made thread safe. [GL #4475]
6370. [bug] Wrong source address used for IPv6 notify messages.
[GL #4669]

17
lib/dns/name.c
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@@ -716,7 +716,7 @@ dns_name_fromregion(dns_name_t *name, const isc_region_t *r) {
unsigned char *offsets;
dns_offsets_t odata;
unsigned int len;
isc_region_t r2;
isc_region_t r2 = { .base = NULL, .length = 0 };
/*
* Make 'name' refer to region 'r'.
@@ -728,6 +728,7 @@ dns_name_fromregion(dns_name_t *name, const isc_region_t *r) {
INIT_OFFSETS(name, offsets, odata);
name->ndata = r->base;
if (name->buffer != NULL) {
isc_buffer_clear(name->buffer);
isc_buffer_availableregion(name->buffer, &r2);
@@ -735,13 +736,8 @@ dns_name_fromregion(dns_name_t *name, const isc_region_t *r) {
if (len > DNS_NAME_MAXWIRE) {
len = DNS_NAME_MAXWIRE;
}
if (len != 0) {
memmove(r2.base, r->base, len);
}
name->ndata = r2.base;
name->length = len;
} else {
name->ndata = r->base;
name->length = (r->length <= DNS_NAME_MAXWIRE)
? r->length
: DNS_NAME_MAXWIRE;
@@ -755,6 +751,15 @@ dns_name_fromregion(dns_name_t *name, const isc_region_t *r) {
}
if (name->buffer != NULL) {
/*
* name->length has been updated by set_offsets to the actual
* length of the name data so we can now copy the actual name
* data and not anything after it.
*/
if (name->length > 0) {
memmove(r2.base, r->base, name->length);
}
name->ndata = r2.base;
isc_buffer_add(name->buffer, name->length);
}
}

20
lib/dns/ncache.c
View File

@@ -42,6 +42,14 @@
*
*/
static uint8_t
atomic_getuint8(isc_buffer_t *b) {
atomic_uchar *cp = isc_buffer_current(b);
uint8_t ret = atomic_load_relaxed(cp);
isc_buffer_forward(b, 1);
return (ret);
}
static isc_result_t
addoptout(dns_message_t *message, dns_db_t *cache, dns_dbnode_t *node,
dns_rdatatype_t covers, isc_stdtime_t now, dns_ttl_t minttl,
@@ -493,10 +501,10 @@ rdataset_count(dns_rdataset_t *rdataset) {
static void
rdataset_settrust(dns_rdataset_t *rdataset, dns_trust_t trust) {
unsigned char *raw;
atomic_uchar *raw;
raw = rdataset->ncache.raw;
raw[-1] = (unsigned char)trust;
raw = (atomic_uchar *)rdataset->ncache.raw;
atomic_store_relaxed(&raw[-1], (unsigned char)trust);
rdataset->trust = trust;
}
@@ -548,7 +556,7 @@ dns_ncache_getrdataset(dns_rdataset_t *ncacherdataset, dns_name_t *name,
ttype = isc_buffer_getuint16(&source);
if (ttype == type && dns_name_equal(&tname, name)) {
trust = isc_buffer_getuint8(&source);
trust = atomic_getuint8(&source);
INSIST(trust <= dns_trust_ultimate);
isc_buffer_remainingregion(&source, &remaining);
break;
@@ -627,7 +635,7 @@ dns_ncache_getsigrdataset(dns_rdataset_t *ncacherdataset, dns_name_t *name,
}
INSIST(remaining.length >= 1);
trust = isc_buffer_getuint8(&source);
trust = atomic_getuint8(&source);
INSIST(trust <= dns_trust_ultimate);
isc_region_consume(&remaining, 1);
@@ -705,7 +713,7 @@ dns_ncache_current(dns_rdataset_t *ncacherdataset, dns_name_t *found,
INSIST(remaining.length >= 5);
type = isc_buffer_getuint16(&source);
trust = isc_buffer_getuint8(&source);
trust = atomic_getuint8(&source);
INSIST(trust <= dns_trust_ultimate);
isc_buffer_remainingregion(&source, &remaining);