diff options
| -rw-r--r-- | include/linux/dns_resolver.h | 4 | ||||
| -rw-r--r-- | include/uapi/linux/dns_resolver.h | 116 | ||||
| -rw-r--r-- | net/dns_resolver/dns_key.c | 67 | ||||
| -rw-r--r-- | net/dns_resolver/dns_query.c | 5 |
4 files changed, 182 insertions, 10 deletions
diff --git a/include/linux/dns_resolver.h b/include/linux/dns_resolver.h index 6ac3cad9aef1..34a744a1bafc 100644 --- a/include/linux/dns_resolver.h +++ b/include/linux/dns_resolver.h @@ -24,11 +24,9 @@ #ifndef _LINUX_DNS_RESOLVER_H #define _LINUX_DNS_RESOLVER_H -#ifdef __KERNEL__ +#include <uapi/linux/dns_resolver.h> extern int dns_query(const char *type, const char *name, size_t namelen, const char *options, char **_result, time64_t *_expiry); -#endif /* KERNEL */ - #endif /* _LINUX_DNS_RESOLVER_H */ diff --git a/include/uapi/linux/dns_resolver.h b/include/uapi/linux/dns_resolver.h new file mode 100644 index 000000000000..129745f9c794 --- /dev/null +++ b/include/uapi/linux/dns_resolver.h @@ -0,0 +1,116 @@ +/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */ +/* DNS resolver interface definitions. + * + * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + */ + +#ifndef _UAPI_LINUX_DNS_RESOLVER_H +#define _UAPI_LINUX_DNS_RESOLVER_H + +#include <linux/types.h> + +/* + * Type of payload. + */ +enum dns_payload_content_type { + DNS_PAYLOAD_IS_SERVER_LIST = 0, /* List of servers, requested by srv=1 */ +}; + +/* + * Type of address that might be found in an address record. + */ +enum dns_payload_address_type { + DNS_ADDRESS_IS_IPV4 = 0, /* 4-byte AF_INET address */ + DNS_ADDRESS_IS_IPV6 = 1, /* 16-byte AF_INET6 address */ +}; + +/* + * Type of protocol used to access a server. + */ +enum dns_payload_protocol_type { + DNS_SERVER_PROTOCOL_UNSPECIFIED = 0, + DNS_SERVER_PROTOCOL_UDP = 1, /* Use UDP to talk to the server */ + DNS_SERVER_PROTOCOL_TCP = 2, /* Use TCP to talk to the server */ +}; + +/* + * Source of record included in DNS resolver payload. + */ +enum dns_record_source { + DNS_RECORD_UNAVAILABLE = 0, /* No source available (empty record) */ + DNS_RECORD_FROM_CONFIG = 1, /* From local configuration data */ + DNS_RECORD_FROM_DNS_A = 2, /* From DNS A or AAAA record */ + DNS_RECORD_FROM_DNS_AFSDB = 3, /* From DNS AFSDB record */ + DNS_RECORD_FROM_DNS_SRV = 4, /* From DNS SRV record */ + DNS_RECORD_FROM_NSS = 5, /* From NSS */ + NR__dns_record_source +}; + +/* + * Status of record included in DNS resolver payload. + */ +enum dns_lookup_status { + DNS_LOOKUP_NOT_DONE = 0, /* No lookup has been made */ + DNS_LOOKUP_GOOD = 1, /* Good records obtained */ + DNS_LOOKUP_GOOD_WITH_BAD = 2, /* Good records, some decoding errors */ + DNS_LOOKUP_BAD = 3, /* Couldn't decode results */ + DNS_LOOKUP_GOT_NOT_FOUND = 4, /* Got a "Not Found" result */ + DNS_LOOKUP_GOT_LOCAL_FAILURE = 5, /* Local failure during lookup */ + DNS_LOOKUP_GOT_TEMP_FAILURE = 6, /* Temporary failure during lookup */ + DNS_LOOKUP_GOT_NS_FAILURE = 7, /* Name server failure */ + NR__dns_lookup_status +}; + +/* + * Header at the beginning of binary format payload. + */ +struct dns_payload_header { + __u8 zero; /* Zero byte: marks this as not being text */ + __u8 content; /* enum dns_payload_content_type */ + __u8 version; /* Encoding version */ +} __packed; + +/* + * Header at the beginning of a V1 server list. This is followed directly by + * the server records. Each server records begins with a struct of type + * dns_server_list_v1_server. + */ +struct dns_server_list_v1_header { + struct dns_payload_header hdr; + __u8 source; /* enum dns_record_source */ + __u8 status; /* enum dns_lookup_status */ + __u8 nr_servers; /* Number of server records following this */ +} __packed; + +/* + * Header at the beginning of each V1 server record. This is followed by the + * characters of the name with no NUL-terminator, followed by the address + * records for that server. Each address record begins with a struct of type + * struct dns_server_list_v1_address. + */ +struct dns_server_list_v1_server { + __u16 name_len; /* Length of name (LE) */ + __u16 priority; /* Priority (as SRV record) (LE) */ + __u16 weight; /* Weight (as SRV record) (LE) */ + __u16 port; /* UDP/TCP port number (LE) */ + __u8 source; /* enum dns_record_source */ + __u8 status; /* enum dns_lookup_status */ + __u8 protocol; /* enum dns_payload_protocol_type */ + __u8 nr_addrs; +} __packed; + +/* + * Header at the beginning of each V1 address record. This is followed by the + * bytes of the address, 4 for IPV4 and 16 for IPV6. + */ +struct dns_server_list_v1_address { + __u8 address_type; /* enum dns_payload_address_type */ +} __packed; + +#endif /* _UAPI_LINUX_DNS_RESOLVER_H */ 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; diff --git a/net/dns_resolver/dns_query.c b/net/dns_resolver/dns_query.c index 49da67034f29..76338c38738a 100644 --- a/net/dns_resolver/dns_query.c +++ b/net/dns_resolver/dns_query.c @@ -148,12 +148,9 @@ int dns_query(const char *type, const char *name, size_t namelen, if (_result) { ret = -ENOMEM; - *_result = kmalloc(len + 1, GFP_KERNEL); + *_result = kmemdup_nul(upayload->data, len, GFP_KERNEL); if (!*_result) goto put; - - memcpy(*_result, upayload->data, len); - (*_result)[len] = '\0'; } if (_expiry) |