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resolve: unify memdup() code when parsing RRs

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Let's make dns_packet_read_public_key() more generic by renaming it to
dns_packet_read_memdup() (which more accurately describes what it
does...). Then, patch all cases where we memdup() RR data to use this
new call.

This specifically checks for zero-length objects, and handles them
gracefully. It will set zero length payload fields as a result.

Special care should be taken to ensure that any code using this call
can handle the returned allocated field to be NULL if the size is
specified as 0!
This commit is contained in:
Lennart Poettering 2015-07-23 04:04:19 +02:00
parent 6aafa9483d
commit f5430a3ef3
3 changed files with 55 additions and 64 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

111
src/resolve/resolved-dns-packet.c
View File

@ -933,6 +933,42 @@ int dns_packet_read_blob(DnsPacket *p, void *d, size_t sz, size_t *start) {
return 0;
}
static int dns_packet_read_memdup(
DnsPacket *p, size_t size,
void **ret, size_t *ret_size,
size_t *ret_start) {
const void *src;
size_t start;
int r;
assert(p);
assert(ret);
r = dns_packet_read(p, size, &src, &start);
if (r < 0)
return r;
if (size <= 0)
*ret = NULL;
else {
void *copy;
copy = memdup(src, size);
if (!copy)
return -ENOMEM;
*ret = copy;
}
if (ret_size)
*ret_size = size;
if (ret_start)
*ret_start = start;
return 0;
}
int dns_packet_read_uint8(DnsPacket *p, uint8_t *ret, size_t *start) {
const void *d;
int r;
@ -1239,26 +1275,6 @@ fail:
return r;
}
static int dns_packet_read_public_key(DnsPacket *p, size_t length,
void **dp, size_t *lengthp,
size_t *start) {
int r;
const void *d;
void *d2;
r = dns_packet_read(p, length, &d, NULL);
if (r < 0)
return r;
d2 = memdup(d, length);
if (!d2)
return -ENOMEM;
*dp = d2;
*lengthp = length;
return 0;
}
static bool loc_size_ok(uint8_t size) {
uint8_t m = size >> 4, e = size & 0xF;
@ -1281,7 +1297,6 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
size_t saved_rindex, offset;
uint16_t rdlength;
const void *d;
int r;
assert(p);
@ -1492,9 +1507,9 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
if (r < 0)
goto fail;
r = dns_packet_read_public_key(p, rdlength - 4,
&rr->ds.digest, &rr->ds.digest_size,
NULL);
r = dns_packet_read_memdup(p, rdlength - 4,
&rr->ds.digest, &rr->ds.digest_size,
NULL);
if (r < 0)
goto fail;
@ -1508,9 +1523,9 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
if (r < 0)
goto fail;
r = dns_packet_read_public_key(p, rdlength - 2,
&rr->sshfp.key, &rr->sshfp.key_size,
NULL);
r = dns_packet_read_memdup(p, rdlength - 2,
&rr->sshfp.key, &rr->sshfp.key_size,
NULL);
break;
case DNS_TYPE_DNSKEY: {
@ -1539,9 +1554,9 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
if (r < 0)
goto fail;
r = dns_packet_read_public_key(p, rdlength - 4,
&rr->dnskey.key, &rr->dnskey.key_size,
NULL);
r = dns_packet_read_memdup(p, rdlength - 4,
&rr->dnskey.key, &rr->dnskey.key_size,
NULL);
break;
}
@ -1578,9 +1593,9 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
if (r < 0)
goto fail;
r = dns_packet_read_public_key(p, offset + rdlength - p->rindex,
&rr->rrsig.signature, &rr->rrsig.signature_size,
NULL);
r = dns_packet_read_memdup(p, offset + rdlength - p->rindex,
&rr->rrsig.signature, &rr->rrsig.signature_size,
NULL);
break;
case DNS_TYPE_NSEC:
@ -1615,34 +1630,18 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
if (r < 0)
goto fail;
rr->nsec3.salt_size = size;
r = dns_packet_read_blob(p, &d, rr->nsec3.salt_size, NULL);
r = dns_packet_read_memdup(p, size, &rr->nsec3.salt, &rr->nsec3.salt_size, NULL);
if (r < 0)
goto fail;
rr->nsec3.salt = memdup(d, rr->nsec3.salt_size);
if (!rr->nsec3.salt) {
r = -ENOMEM;
goto fail;
}
r = dns_packet_read_uint8(p, &size, NULL);
if (r < 0)
goto fail;
rr->nsec3.next_hashed_name_size = size;
r = dns_packet_read(p, rr->nsec3.next_hashed_name_size, &d, NULL);
r = dns_packet_read_memdup(p, size, &rr->nsec3.next_hashed_name, &rr->nsec3.next_hashed_name_size, NULL);
if (r < 0)
goto fail;
rr->nsec3.next_hashed_name = memdup(d, rr->nsec3.next_hashed_name_size);
if (!rr->nsec3.next_hashed_name) {
r = -ENOMEM;
goto fail;
}
r = dns_packet_append_types(p, rr->nsec3.types, NULL);
if (r < 0)
goto fail;
@ -1651,17 +1650,9 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
}
default:
unparseable:
r = dns_packet_read(p, rdlength, &d, NULL);
r = dns_packet_read_memdup(p, rdlength, &rr->generic.data, &rr->generic.size, NULL);
if (r < 0)
goto fail;
rr->generic.data = memdup(d, rdlength);
if (!rr->generic.data) {
r = -ENOMEM;
goto fail;
}
rr->generic.size = rdlength;
break;
}
if (r < 0)

6
src/resolve/resolved-dns-rr.c
View File

@ -776,7 +776,7 @@ int dns_resource_record_to_string(const DnsResourceRecord *rr, char **ret) {
case DNS_TYPE_NSEC3: {
_cleanup_free_ char *salt = NULL, *hash = NULL;
if (rr->nsec3.salt_size) {
if (rr->nsec3.salt_size > 0) {
salt = hexmem(rr->nsec3.salt, rr->nsec3.salt_size);
if (!salt)
return -ENOMEM;
@ -795,7 +795,7 @@ int dns_resource_record_to_string(const DnsResourceRecord *rr, char **ret) {
rr->nsec3.algorithm,
rr->nsec3.flags,
rr->nsec3.iterations,
rr->nsec3.salt_size ? salt : "-",
rr->nsec3.salt_size > 0 ? salt : "-",
hash,
t);
if (r < 0)
@ -809,7 +809,7 @@ int dns_resource_record_to_string(const DnsResourceRecord *rr, char **ret) {
if (!t)
return -ENOMEM;
r = asprintf(&s, "%s \\# %"PRIu8" %s", k, rr->generic.size, t);
r = asprintf(&s, "%s \\# %zu %s", k, rr->generic.size, t);
if (r < 0)
return -ENOMEM;
break;

2
src/resolve/resolved-dns-rr.h
View File

@ -53,7 +53,7 @@ struct DnsResourceRecord {
union {
struct {
void *data;
uint16_t size;
size_t size;
} generic;
struct {