| 1 | /* Netfilter messages via netlink socket. Allows for user space |
| 2 | * protocol helpers and general trouble making from userspace. |
| 3 | * |
| 4 | * (C) 2001 by Jay Schulist <jschlst@samba.org>, |
| 5 | * (C) 2002-2005 by Harald Welte <laforge@gnumonks.org> |
| 6 | * (C) 2005 by Pablo Neira Ayuso <pablo@eurodev.net> |
| 7 | * |
| 8 | * Initial netfilter messages via netlink development funded and |
| 9 | * generally made possible by Network Robots, Inc. (www.networkrobots.com) |
| 10 | * |
| 11 | * Further development of this code funded by Astaro AG (http://www.astaro.com) |
| 12 | * |
| 13 | * This software may be used and distributed according to the terms |
| 14 | * of the GNU General Public License, incorporated herein by reference. |
| 15 | */ |
| 16 | |
| 17 | #include <linux/config.h> |
| 18 | #include <linux/module.h> |
| 19 | #include <linux/types.h> |
| 20 | #include <linux/socket.h> |
| 21 | #include <linux/kernel.h> |
| 22 | #include <linux/major.h> |
| 23 | #include <linux/sched.h> |
| 24 | #include <linux/timer.h> |
| 25 | #include <linux/string.h> |
| 26 | #include <linux/sockios.h> |
| 27 | #include <linux/net.h> |
| 28 | #include <linux/fcntl.h> |
| 29 | #include <linux/skbuff.h> |
| 30 | #include <asm/uaccess.h> |
| 31 | #include <asm/system.h> |
| 32 | #include <net/sock.h> |
| 33 | #include <linux/init.h> |
| 34 | #include <linux/spinlock.h> |
| 35 | |
| 36 | #include <linux/netfilter.h> |
| 37 | #include <linux/netlink.h> |
| 38 | #include <linux/netfilter/nfnetlink.h> |
| 39 | |
| 40 | MODULE_LICENSE("GPL"); |
| 41 | MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); |
| 42 | MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER); |
| 43 | |
| 44 | static char __initdata nfversion[] = "0.30"; |
| 45 | |
| 46 | #if 0 |
| 47 | #define DEBUGP printk |
| 48 | #else |
| 49 | #define DEBUGP(format, args...) |
| 50 | #endif |
| 51 | |
| 52 | static struct sock *nfnl = NULL; |
| 53 | static struct nfnetlink_subsystem *subsys_table[NFNL_SUBSYS_COUNT]; |
| 54 | DECLARE_MUTEX(nfnl_sem); |
| 55 | |
| 56 | void nfnl_lock(void) |
| 57 | { |
| 58 | nfnl_shlock(); |
| 59 | } |
| 60 | |
| 61 | void nfnl_unlock(void) |
| 62 | { |
| 63 | nfnl_shunlock(); |
| 64 | } |
| 65 | |
| 66 | int nfnetlink_subsys_register(struct nfnetlink_subsystem *n) |
| 67 | { |
| 68 | DEBUGP("registering subsystem ID %u\n", n->subsys_id); |
| 69 | |
| 70 | /* If the netlink socket wasn't created, then fail */ |
| 71 | if (!nfnl) |
| 72 | return -1; |
| 73 | |
| 74 | nfnl_lock(); |
| 75 | subsys_table[n->subsys_id] = n; |
| 76 | nfnl_unlock(); |
| 77 | |
| 78 | return 0; |
| 79 | } |
| 80 | |
| 81 | int nfnetlink_subsys_unregister(struct nfnetlink_subsystem *n) |
| 82 | { |
| 83 | DEBUGP("unregistering subsystem ID %u\n", n->subsys_id); |
| 84 | |
| 85 | nfnl_lock(); |
| 86 | subsys_table[n->subsys_id] = NULL; |
| 87 | nfnl_unlock(); |
| 88 | |
| 89 | return 0; |
| 90 | } |
| 91 | |
| 92 | static inline struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t type) |
| 93 | { |
| 94 | u_int8_t subsys_id = NFNL_SUBSYS_ID(type); |
| 95 | |
| 96 | if (subsys_id >= NFNL_SUBSYS_COUNT |
| 97 | || subsys_table[subsys_id] == NULL) |
| 98 | return NULL; |
| 99 | |
| 100 | return subsys_table[subsys_id]; |
| 101 | } |
| 102 | |
| 103 | static inline struct nfnl_callback * |
| 104 | nfnetlink_find_client(u_int16_t type, struct nfnetlink_subsystem *ss) |
| 105 | { |
| 106 | u_int8_t cb_id = NFNL_MSG_TYPE(type); |
| 107 | |
| 108 | if (cb_id >= ss->cb_count) { |
| 109 | DEBUGP("msgtype %u >= %u, returning\n", type, ss->cb_count); |
| 110 | return NULL; |
| 111 | } |
| 112 | |
| 113 | return &ss->cb[cb_id]; |
| 114 | } |
| 115 | |
| 116 | void __nfa_fill(struct sk_buff *skb, int attrtype, int attrlen, |
| 117 | const void *data) |
| 118 | { |
| 119 | struct nfattr *nfa; |
| 120 | int size = NFA_LENGTH(attrlen); |
| 121 | |
| 122 | nfa = (struct nfattr *)skb_put(skb, NFA_ALIGN(size)); |
| 123 | nfa->nfa_type = attrtype; |
| 124 | nfa->nfa_len = size; |
| 125 | memcpy(NFA_DATA(nfa), data, attrlen); |
| 126 | memset(NFA_DATA(nfa) + attrlen, 0, NFA_ALIGN(size) - size); |
| 127 | } |
| 128 | |
| 129 | int nfattr_parse(struct nfattr *tb[], int maxattr, struct nfattr *nfa, int len) |
| 130 | { |
| 131 | memset(tb, 0, sizeof(struct nfattr *) * maxattr); |
| 132 | |
| 133 | while (NFA_OK(nfa, len)) { |
| 134 | unsigned flavor = nfa->nfa_type; |
| 135 | if (flavor && flavor <= maxattr) |
| 136 | tb[flavor-1] = nfa; |
| 137 | nfa = NFA_NEXT(nfa, len); |
| 138 | } |
| 139 | |
| 140 | return 0; |
| 141 | } |
| 142 | |
| 143 | /** |
| 144 | * nfnetlink_check_attributes - check and parse nfnetlink attributes |
| 145 | * |
| 146 | * subsys: nfnl subsystem for which this message is to be parsed |
| 147 | * nlmsghdr: netlink message to be checked/parsed |
| 148 | * cda: array of pointers, needs to be at least subsys->attr_count big |
| 149 | * |
| 150 | */ |
| 151 | static int |
| 152 | nfnetlink_check_attributes(struct nfnetlink_subsystem *subsys, |
| 153 | struct nlmsghdr *nlh, struct nfattr *cda[]) |
| 154 | { |
| 155 | int min_len; |
| 156 | |
| 157 | memset(cda, 0, sizeof(struct nfattr *) * subsys->attr_count); |
| 158 | |
| 159 | /* check attribute lengths. */ |
| 160 | min_len = NLMSG_ALIGN(sizeof(struct nfgenmsg)); |
| 161 | if (nlh->nlmsg_len < min_len) |
| 162 | return -EINVAL; |
| 163 | |
| 164 | if (nlh->nlmsg_len > min_len) { |
| 165 | struct nfattr *attr = NFM_NFA(NLMSG_DATA(nlh)); |
| 166 | int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len); |
| 167 | |
| 168 | while (NFA_OK(attr, attrlen)) { |
| 169 | unsigned flavor = attr->nfa_type; |
| 170 | if (flavor) { |
| 171 | if (flavor > subsys->attr_count) |
| 172 | return -EINVAL; |
| 173 | cda[flavor - 1] = attr; |
| 174 | } |
| 175 | attr = NFA_NEXT(attr, attrlen); |
| 176 | } |
| 177 | } else |
| 178 | return -EINVAL; |
| 179 | |
| 180 | return 0; |
| 181 | } |
| 182 | |
| 183 | int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group, int echo) |
| 184 | { |
| 185 | int allocation = in_interrupt() ? GFP_ATOMIC : GFP_KERNEL; |
| 186 | int err = 0; |
| 187 | |
| 188 | NETLINK_CB(skb).dst_groups = group; |
| 189 | if (echo) |
| 190 | atomic_inc(&skb->users); |
| 191 | netlink_broadcast(nfnl, skb, pid, group, allocation); |
| 192 | if (echo) |
| 193 | err = netlink_unicast(nfnl, skb, pid, MSG_DONTWAIT); |
| 194 | |
| 195 | return err; |
| 196 | } |
| 197 | |
| 198 | int nfnetlink_unicast(struct sk_buff *skb, u_int32_t pid, int flags) |
| 199 | { |
| 200 | return netlink_unicast(nfnl, skb, pid, flags); |
| 201 | } |
| 202 | |
| 203 | /* Process one complete nfnetlink message. */ |
| 204 | static inline int nfnetlink_rcv_msg(struct sk_buff *skb, |
| 205 | struct nlmsghdr *nlh, int *errp) |
| 206 | { |
| 207 | struct nfnl_callback *nc; |
| 208 | struct nfnetlink_subsystem *ss; |
| 209 | int type, err = 0; |
| 210 | |
| 211 | DEBUGP("entered; subsys=%u, msgtype=%u\n", |
| 212 | NFNL_SUBSYS_ID(nlh->nlmsg_type), |
| 213 | NFNL_MSG_TYPE(nlh->nlmsg_type)); |
| 214 | |
| 215 | /* Only requests are handled by kernel now. */ |
| 216 | if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) { |
| 217 | DEBUGP("received non-request message\n"); |
| 218 | return 0; |
| 219 | } |
| 220 | |
| 221 | /* All the messages must at least contain nfgenmsg */ |
| 222 | if (nlh->nlmsg_len < |
| 223 | NLMSG_LENGTH(NLMSG_ALIGN(sizeof(struct nfgenmsg)))) { |
| 224 | DEBUGP("received message was too short\n"); |
| 225 | return 0; |
| 226 | } |
| 227 | |
| 228 | type = nlh->nlmsg_type; |
| 229 | ss = nfnetlink_get_subsys(type); |
| 230 | if (!ss) |
| 231 | goto err_inval; |
| 232 | |
| 233 | nc = nfnetlink_find_client(type, ss); |
| 234 | if (!nc) { |
| 235 | DEBUGP("unable to find client for type %d\n", type); |
| 236 | goto err_inval; |
| 237 | } |
| 238 | |
| 239 | if (nc->cap_required && |
| 240 | !cap_raised(NETLINK_CB(skb).eff_cap, nc->cap_required)) { |
| 241 | DEBUGP("permission denied for type %d\n", type); |
| 242 | *errp = -EPERM; |
| 243 | return -1; |
| 244 | } |
| 245 | |
| 246 | { |
| 247 | struct nfattr *cda[ss->attr_count]; |
| 248 | |
| 249 | memset(cda, 0, ss->attr_count*sizeof(struct nfattr *)); |
| 250 | |
| 251 | err = nfnetlink_check_attributes(ss, nlh, cda); |
| 252 | if (err < 0) |
| 253 | goto err_inval; |
| 254 | |
| 255 | err = nc->call(nfnl, skb, nlh, cda, errp); |
| 256 | *errp = err; |
| 257 | return err; |
| 258 | } |
| 259 | |
| 260 | err_inval: |
| 261 | *errp = -EINVAL; |
| 262 | return -1; |
| 263 | } |
| 264 | |
| 265 | /* Process one packet of messages. */ |
| 266 | static inline int nfnetlink_rcv_skb(struct sk_buff *skb) |
| 267 | { |
| 268 | int err; |
| 269 | struct nlmsghdr *nlh; |
| 270 | |
| 271 | while (skb->len >= NLMSG_SPACE(0)) { |
| 272 | u32 rlen; |
| 273 | |
| 274 | nlh = (struct nlmsghdr *)skb->data; |
| 275 | if (nlh->nlmsg_len < sizeof(struct nlmsghdr) |
| 276 | || skb->len < nlh->nlmsg_len) |
| 277 | return 0; |
| 278 | rlen = NLMSG_ALIGN(nlh->nlmsg_len); |
| 279 | if (rlen > skb->len) |
| 280 | rlen = skb->len; |
| 281 | if (nfnetlink_rcv_msg(skb, nlh, &err)) { |
| 282 | if (!err) |
| 283 | return -1; |
| 284 | netlink_ack(skb, nlh, err); |
| 285 | } else |
| 286 | if (nlh->nlmsg_flags & NLM_F_ACK) |
| 287 | netlink_ack(skb, nlh, 0); |
| 288 | skb_pull(skb, rlen); |
| 289 | } |
| 290 | |
| 291 | return 0; |
| 292 | } |
| 293 | |
| 294 | static void nfnetlink_rcv(struct sock *sk, int len) |
| 295 | { |
| 296 | do { |
| 297 | struct sk_buff *skb; |
| 298 | |
| 299 | if (nfnl_shlock_nowait()) |
| 300 | return; |
| 301 | |
| 302 | while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) { |
| 303 | if (nfnetlink_rcv_skb(skb)) { |
| 304 | if (skb->len) |
| 305 | skb_queue_head(&sk->sk_receive_queue, |
| 306 | skb); |
| 307 | else |
| 308 | kfree_skb(skb); |
| 309 | break; |
| 310 | } |
| 311 | kfree_skb(skb); |
| 312 | } |
| 313 | |
| 314 | up(&nfnl_sem); |
| 315 | } while(nfnl && nfnl->sk_receive_queue.qlen); |
| 316 | } |
| 317 | |
| 318 | void __exit nfnetlink_exit(void) |
| 319 | { |
| 320 | printk("Removing netfilter NETLINK layer.\n"); |
| 321 | sock_release(nfnl->sk_socket); |
| 322 | return; |
| 323 | } |
| 324 | |
| 325 | int __init nfnetlink_init(void) |
| 326 | { |
| 327 | printk("Netfilter messages via NETLINK v%s.\n", nfversion); |
| 328 | |
| 329 | nfnl = netlink_kernel_create(NETLINK_NETFILTER, nfnetlink_rcv, |
| 330 | THIS_MODULE); |
| 331 | if (!nfnl) { |
| 332 | printk(KERN_ERR "cannot initialize nfnetlink!\n"); |
| 333 | return -1; |
| 334 | } |
| 335 | |
| 336 | return 0; |
| 337 | } |
| 338 | |
| 339 | module_init(nfnetlink_init); |
| 340 | module_exit(nfnetlink_exit); |
| 341 | |
| 342 | EXPORT_SYMBOL_GPL(nfnetlink_subsys_register); |
| 343 | EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister); |
| 344 | EXPORT_SYMBOL_GPL(nfnetlink_send); |
| 345 | EXPORT_SYMBOL_GPL(nfnetlink_unicast); |
| 346 | EXPORT_SYMBOL_GPL(nfattr_parse); |
| 347 | EXPORT_SYMBOL_GPL(__nfa_fill); |