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path: root/net/dns_resolver/dns_key.c
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Diffstat (limited to 'net/dns_resolver/dns_key.c')
-rw-r--r--net/dns_resolver/dns_key.c67
1 files changed, 64 insertions, 3 deletions
diff --git a/net/dns_resolver/dns_key.c b/net/dns_resolver/dns_key.c
index 7f4534828f6c..a65d553e730d 100644
--- a/net/dns_resolver/dns_key.c
+++ b/net/dns_resolver/dns_key.c
@@ -29,6 +29,7 @@
#include <linux/keyctl.h>
#include <linux/err.h>
#include <linux/seq_file.h>
+#include <linux/dns_resolver.h>
#include <keys/dns_resolver-type.h>
#include <keys/user-type.h>
#include "internal.h"
@@ -48,27 +49,86 @@ const struct cred *dns_resolver_cache;
/*
* Preparse instantiation data for a dns_resolver key.
*
- * The data must be a NUL-terminated string, with the NUL char accounted in
- * datalen.
+ * For normal hostname lookups, the data must be a NUL-terminated string, with
+ * the NUL char accounted in datalen.
*
* If the data contains a '#' characters, then we take the clause after each
* one to be an option of the form 'key=value'. The actual data of interest is
* the string leading up to the first '#'. For instance:
*
* "ip1,ip2,...#foo=bar"
+ *
+ * For server list requests, the data must begin with a NUL char and be
+ * followed by a byte indicating the version of the data format. Version 1
+ * looks something like (note this is packed):
+ *
+ * u8 Non-string marker (ie. 0)
+ * u8 Content (DNS_PAYLOAD_IS_*)
+ * u8 Version (e.g. 1)
+ * u8 Source of server list
+ * u8 Lookup status of server list
+ * u8 Number of servers
+ * foreach-server {
+ * __le16 Name length
+ * __le16 Priority (as per SRV record, low first)
+ * __le16 Weight (as per SRV record, higher first)
+ * __le16 Port
+ * u8 Source of address list
+ * u8 Lookup status of address list
+ * u8 Protocol (DNS_SERVER_PROTOCOL_*)
+ * u8 Number of addresses
+ * char[] Name (not NUL-terminated)
+ * foreach-address {
+ * u8 Family (DNS_ADDRESS_IS_*)
+ * union {
+ * u8[4] ipv4_addr
+ * u8[16] ipv6_addr
+ * }
+ * }
+ * }
+ *
*/
static int
dns_resolver_preparse(struct key_preparsed_payload *prep)
{
+ const struct dns_payload_header *bin;
struct user_key_payload *upayload;
unsigned long derrno;
int ret;
int datalen = prep->datalen, result_len = 0;
const char *data = prep->data, *end, *opt;
+ if (datalen <= 1 || !data)
+ return -EINVAL;
+
+ if (data[0] == 0) {
+ /* It may be a server list. */
+ if (datalen <= sizeof(*bin))
+ return -EINVAL;
+
+ bin = (const struct dns_payload_header *)data;
+ kenter("[%u,%u],%u", bin->content, bin->version, datalen);
+ if (bin->content != DNS_PAYLOAD_IS_SERVER_LIST) {
+ pr_warn_ratelimited(
+ "dns_resolver: Unsupported content type (%u)\n",
+ bin->content);
+ return -EINVAL;
+ }
+
+ if (bin->version != 1) {
+ pr_warn_ratelimited(
+ "dns_resolver: Unsupported server list version (%u)\n",
+ bin->version);
+ return -EINVAL;
+ }
+
+ result_len = datalen;
+ goto store_result;
+ }
+
kenter("'%*.*s',%u", datalen, datalen, data, datalen);
- if (datalen <= 1 || !data || data[datalen - 1] != '\0')
+ if (!data || data[datalen - 1] != '\0')
return -EINVAL;
datalen--;
@@ -144,6 +204,7 @@ dns_resolver_preparse(struct key_preparsed_payload *prep)
return 0;
}
+store_result:
kdebug("store result");
prep->quotalen = result_len;