[NET]: Protocol Independant Policy Routing Rules Framework

Derived from net/ipv/fib_rules.c

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/fib_rules.h b/include/linux/fib_rules.h
new file mode 100644 (file)
index 0000000..5e503f0
--- /dev/null
+++ b/include/linux/fib_rules.h
@@ -0,0 +1,60 @@
+#ifndef __LINUX_FIB_RULES_H
+#define __LINUX_FIB_RULES_H
+
+#include <linux/types.h>
+#include <linux/rtnetlink.h>
+
+/* rule is permanent, and cannot be deleted */
+#define FIB_RULE_PERMANENT     1
+
+struct fib_rule_hdr
+{
+       __u8            family;
+       __u8            dst_len;
+       __u8            src_len;
+       __u8            tos;
+
+       __u8            table;
+       __u8            res1;   /* reserved */
+       __u8            res2;   /* reserved */
+       __u8            action;
+
+       __u32           flags;
+};
+
+enum
+{
+       FRA_UNSPEC,
+       FRA_DST,        /* destination address */
+       FRA_SRC,        /* source address */
+       FRA_IFNAME,     /* interface name */
+       FRA_UNUSED1,
+       FRA_UNUSED2,
+       FRA_PRIORITY,   /* priority/preference */
+       FRA_UNUSED3,
+       FRA_UNUSED4,
+       FRA_UNUSED5,
+       FRA_FWMARK,     /* netfilter mark (IPv4) */
+       FRA_FLOW,       /* flow/class id */
+       __FRA_MAX
+};
+
+#define FRA_MAX (__FRA_MAX - 1)
+
+enum
+{
+       FR_ACT_UNSPEC,
+       FR_ACT_TO_TBL,          /* Pass to fixed table */
+       FR_ACT_RES1,
+       FR_ACT_RES2,
+       FR_ACT_RES3,
+       FR_ACT_RES4,
+       FR_ACT_BLACKHOLE,       /* Drop without notification */
+       FR_ACT_UNREACHABLE,     /* Drop with ENETUNREACH */
+       FR_ACT_PROHIBIT,        /* Drop with EACCES */
+       __FR_ACT_MAX,
+};
+
+#define FR_ACT_MAX (__FR_ACT_MAX - 1)
+
+#endif

diff --git a/include/net/fib_rules.h b/include/net/fib_rules.h
new file mode 100644 (file)
index 0000000..61375d9
--- /dev/null
+++ b/include/net/fib_rules.h
@@ -0,0 +1,90 @@
+#ifndef __NET_FIB_RULES_H
+#define __NET_FIB_RULES_H
+
+#include <linux/types.h>
+#include <linux/netdevice.h>
+#include <linux/fib_rules.h>
+#include <net/flow.h>
+#include <net/netlink.h>
+
+struct fib_rule
+{
+       struct list_head        list;
+       atomic_t                refcnt;
+       int                     ifindex;
+       char                    ifname[IFNAMSIZ];
+       u32                     pref;
+       u32                     flags;
+       u32                     table;
+       u8                      action;
+       struct rcu_head         rcu;
+};
+
+struct fib_lookup_arg
+{
+       void                    *lookup_ptr;
+       void                    *result;
+       struct fib_rule         *rule;
+};
+
+struct fib_rules_ops
+{
+       int                     family;
+       struct list_head        list;
+       int                     rule_size;
+
+       int                     (*action)(struct fib_rule *,
+                                         struct flowi *, int,
+                                         struct fib_lookup_arg *);
+       int                     (*match)(struct fib_rule *,
+                                        struct flowi *, int);
+       int                     (*configure)(struct fib_rule *,
+                                            struct sk_buff *,
+                                            struct nlmsghdr *,
+                                            struct fib_rule_hdr *,
+                                            struct nlattr **);
+       int                     (*compare)(struct fib_rule *,
+                                          struct fib_rule_hdr *,
+                                          struct nlattr **);
+       int                     (*fill)(struct fib_rule *, struct sk_buff *,
+                                       struct nlmsghdr *,
+                                       struct fib_rule_hdr *);
+       u32                     (*default_pref)(void);
+
+       int                     nlgroup;
+       struct nla_policy       *policy;
+       struct list_head        *rules_list;
+       struct module           *owner;
+};
+
+static inline void fib_rule_get(struct fib_rule *rule)
+{
+       atomic_inc(&rule->refcnt);
+}
+
+static inline void fib_rule_put_rcu(struct rcu_head *head)
+{
+       struct fib_rule *rule = container_of(head, struct fib_rule, rcu);
+       kfree(rule);
+}
+
+static inline void fib_rule_put(struct fib_rule *rule)
+{
+       if (atomic_dec_and_test(&rule->refcnt))
+               call_rcu(&rule->rcu, fib_rule_put_rcu);
+}
+
+extern int                     fib_rules_register(struct fib_rules_ops *);
+extern int                     fib_rules_unregister(struct fib_rules_ops *);
+
+extern int                     fib_rules_lookup(struct fib_rules_ops *,
+                                                struct flowi *, int flags,
+                                                struct fib_lookup_arg *);
+
+extern int                     fib_nl_newrule(struct sk_buff *,
+                                              struct nlmsghdr *, void *);
+extern int                     fib_nl_delrule(struct sk_buff *,
+                                              struct nlmsghdr *, void *);
+extern int                     fib_rules_dump(struct sk_buff *,
+                                              struct netlink_callback *, int);
+#endif

diff --git a/net/Kconfig b/net/Kconfig
index eb855b7..6528a93 100644 (file)
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -251,6 +251,9 @@ config WIRELESS_EXT
 
 source "net/netlabel/Kconfig"
 
+config FIB_RULES
+       bool
+
 endif   # if NET
 endmenu # Networking
 

diff --git a/net/core/Makefile b/net/core/Makefile
index 2645ba4..1195680 100644 (file)
--- a/net/core/Makefile
+++ b/net/core/Makefile
@@ -17,3 +17,4 @@ obj-$(CONFIG_NET_PKTGEN) += pktgen.o
 obj-$(CONFIG_WIRELESS_EXT) += wireless.o
 obj-$(CONFIG_NETPOLL) += netpoll.o
 obj-$(CONFIG_NET_DMA) += user_dma.o
+obj-$(CONFIG_FIB_RULES) += fib_rules.o

diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
new file mode 100644 (file)
index 0000000..6cdad24
--- /dev/null
+++ b/net/core/fib_rules.c
@@ -0,0 +1,416 @@
+/*
+ * net/core/fib_rules.c                Generic Routing Rules
+ *
+ *     This program is free software; you can redistribute it and/or
+ *     modify it under the terms of the GNU General Public License as
+ *     published by the Free Software Foundation, version 2.
+ *
+ * Authors:    Thomas Graf <tgraf@suug.ch>
+ */
+
+#include <linux/config.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <net/fib_rules.h>
+
+static LIST_HEAD(rules_ops);
+static DEFINE_SPINLOCK(rules_mod_lock);
+
+static void notify_rule_change(int event, struct fib_rule *rule,
+                              struct fib_rules_ops *ops);
+
+static struct fib_rules_ops *lookup_rules_ops(int family)
+{
+       struct fib_rules_ops *ops;
+
+       rcu_read_lock();
+       list_for_each_entry_rcu(ops, &rules_ops, list) {
+               if (ops->family == family) {
+                       if (!try_module_get(ops->owner))
+                               ops = NULL;
+                       rcu_read_unlock();
+                       return ops;
+               }
+       }
+       rcu_read_unlock();
+
+       return NULL;
+}
+
+static void rules_ops_put(struct fib_rules_ops *ops)
+{
+       if (ops)
+               module_put(ops->owner);
+}
+
+int fib_rules_register(struct fib_rules_ops *ops)
+{
+       int err = -EEXIST;
+       struct fib_rules_ops *o;
+
+       if (ops->rule_size < sizeof(struct fib_rule))
+               return -EINVAL;
+
+       if (ops->match == NULL || ops->configure == NULL ||
+           ops->compare == NULL || ops->fill == NULL ||
+           ops->action == NULL)
+               return -EINVAL;
+
+       spin_lock(&rules_mod_lock);
+       list_for_each_entry(o, &rules_ops, list)
+               if (ops->family == o->family)
+                       goto errout;
+
+       list_add_tail_rcu(&ops->list, &rules_ops);
+       err = 0;
+errout:
+       spin_unlock(&rules_mod_lock);
+
+       return err;
+}
+
+EXPORT_SYMBOL_GPL(fib_rules_register);
+
+static void cleanup_ops(struct fib_rules_ops *ops)
+{
+       struct fib_rule *rule, *tmp;
+
+       list_for_each_entry_safe(rule, tmp, ops->rules_list, list) {
+               list_del_rcu(&rule->list);
+               fib_rule_put(rule);
+       }
+}
+
+int fib_rules_unregister(struct fib_rules_ops *ops)
+{
+       int err = 0;
+       struct fib_rules_ops *o;
+
+       spin_lock(&rules_mod_lock);
+       list_for_each_entry(o, &rules_ops, list) {
+               if (o == ops) {
+                       list_del_rcu(&o->list);
+                       cleanup_ops(ops);
+                       goto out;
+               }
+       }
+
+       err = -ENOENT;
+out:
+       spin_unlock(&rules_mod_lock);
+
+       synchronize_rcu();
+
+       return err;
+}
+
+EXPORT_SYMBOL_GPL(fib_rules_unregister);
+
+int fib_rules_lookup(struct fib_rules_ops *ops, struct flowi *fl,
+                    int flags, struct fib_lookup_arg *arg)
+{
+       struct fib_rule *rule;
+       int err;
+
+       rcu_read_lock();
+
+       list_for_each_entry_rcu(rule, ops->rules_list, list) {
+               if (rule->ifindex && (rule->ifindex != fl->iif))
+                       continue;
+
+               if (!ops->match(rule, fl, flags))
+                       continue;
+
+               err = ops->action(rule, fl, flags, arg);
+               if (err != -EAGAIN) {
+                       fib_rule_get(rule);
+                       arg->rule = rule;
+                       goto out;
+               }
+       }
+
+       err = -ENETUNREACH;
+out:
+       rcu_read_unlock();
+
+       return err;
+}
+
+EXPORT_SYMBOL_GPL(fib_rules_lookup);
+
+int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
+{
+       struct fib_rule_hdr *frh = nlmsg_data(nlh);
+       struct fib_rules_ops *ops = NULL;
+       struct fib_rule *rule, *r, *last = NULL;
+       struct nlattr *tb[FRA_MAX+1];
+       int err = -EINVAL;
+
+       if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
+               goto errout;
+
+       ops = lookup_rules_ops(frh->family);
+       if (ops == NULL) {
+               err = EAFNOSUPPORT;
+               goto errout;
+       }
+
+       err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
+       if (err < 0)
+               goto errout;
+
+       if (tb[FRA_IFNAME] && nla_len(tb[FRA_IFNAME]) > IFNAMSIZ)
+               goto errout;
+
+       rule = kzalloc(ops->rule_size, GFP_KERNEL);
+       if (rule == NULL) {
+               err = -ENOMEM;
+               goto errout;
+       }
+
+       if (tb[FRA_PRIORITY])
+               rule->pref = nla_get_u32(tb[FRA_PRIORITY]);
+
+       if (tb[FRA_IFNAME]) {
+               struct net_device *dev;
+
+               rule->ifindex = -1;
+               if (nla_strlcpy(rule->ifname, tb[FRA_IFNAME],
+                               IFNAMSIZ) >= IFNAMSIZ)
+                       goto errout_free;
+
+               dev = __dev_get_by_name(rule->ifname);
+               if (dev)
+                       rule->ifindex = dev->ifindex;
+       }
+
+       rule->action = frh->action;
+       rule->flags = frh->flags;
+       rule->table = frh->table;
+
+       if (!rule->pref && ops->default_pref)
+               rule->pref = ops->default_pref();
+
+       err = ops->configure(rule, skb, nlh, frh, tb);
+       if (err < 0)
+               goto errout_free;
+
+       list_for_each_entry(r, ops->rules_list, list) {
+               if (r->pref > rule->pref)
+                       break;
+               last = r;
+       }
+
+       fib_rule_get(rule);
+
+       if (last)
+               list_add_rcu(&rule->list, &last->list);
+       else
+               list_add_rcu(&rule->list, ops->rules_list);
+
+       notify_rule_change(RTM_NEWRULE, rule, ops);
+       rules_ops_put(ops);
+       return 0;
+
+errout_free:
+       kfree(rule);
+errout:
+       rules_ops_put(ops);
+       return err;
+}
+
+int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
+{
+       struct fib_rule_hdr *frh = nlmsg_data(nlh);
+       struct fib_rules_ops *ops = NULL;
+       struct fib_rule *rule;
+       struct nlattr *tb[FRA_MAX+1];
+       int err = -EINVAL;
+
+       if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
+               goto errout;
+
+       ops = lookup_rules_ops(frh->family);
+       if (ops == NULL) {
+               err = EAFNOSUPPORT;
+               goto errout;
+       }
+
+       err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
+       if (err < 0)
+               goto errout;
+
+       list_for_each_entry(rule, ops->rules_list, list) {
+               if (frh->action && (frh->action != rule->action))
+                       continue;
+
+               if (frh->table && (frh->table != rule->table))
+                       continue;
+
+               if (tb[FRA_PRIORITY] &&
+                   (rule->pref != nla_get_u32(tb[FRA_PRIORITY])))
+                       continue;
+
+               if (tb[FRA_IFNAME] &&
+                   nla_strcmp(tb[FRA_IFNAME], rule->ifname))
+                       continue;
+
+               if (!ops->compare(rule, frh, tb))
+                       continue;
+
+               if (rule->flags & FIB_RULE_PERMANENT) {
+                       err = -EPERM;
+                       goto errout;
+               }
+
+               list_del_rcu(&rule->list);
+               synchronize_rcu();
+               notify_rule_change(RTM_DELRULE, rule, ops);
+               fib_rule_put(rule);
+               rules_ops_put(ops);
+               return 0;
+       }
+
+       err = -ENOENT;
+errout:
+       rules_ops_put(ops);
+       return err;
+}
+
+static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
+                           u32 pid, u32 seq, int type, int flags,
+                           struct fib_rules_ops *ops)
+{
+       struct nlmsghdr *nlh;
+       struct fib_rule_hdr *frh;
+
+       nlh = nlmsg_put(skb, pid, seq, type, sizeof(*frh), flags);
+       if (nlh == NULL)
+               return -1;
+
+       frh = nlmsg_data(nlh);
+       frh->table = rule->table;
+       frh->res1 = 0;
+       frh->res2 = 0;
+       frh->action = rule->action;
+       frh->flags = rule->flags;
+
+       if (rule->ifname[0])
+               NLA_PUT_STRING(skb, FRA_IFNAME, rule->ifname);
+
+       if (rule->pref)
+               NLA_PUT_U32(skb, FRA_PRIORITY, rule->pref);
+
+       if (ops->fill(rule, skb, nlh, frh) < 0)
+               goto nla_put_failure;
+
+       return nlmsg_end(skb, nlh);
+
+nla_put_failure:
+       return nlmsg_cancel(skb, nlh);
+}
+
+int fib_rules_dump(struct sk_buff *skb, struct netlink_callback *cb, int family)
+{
+       int idx = 0;
+       struct fib_rule *rule;
+       struct fib_rules_ops *ops;
+
+       ops = lookup_rules_ops(family);
+       if (ops == NULL)
+               return -EAFNOSUPPORT;
+
+       rcu_read_lock();
+       list_for_each_entry(rule, ops->rules_list, list) {
+               if (idx < cb->args[0])
+                       goto skip;
+
+               if (fib_nl_fill_rule(skb, rule, NETLINK_CB(cb->skb).pid,
+                                    cb->nlh->nlmsg_seq, RTM_NEWRULE,
+                                    NLM_F_MULTI, ops) < 0)
+                       break;
+skip:
+               idx++;
+       }
+       rcu_read_unlock();
+       cb->args[0] = idx;
+       rules_ops_put(ops);
+
+       return skb->len;
+}
+
+EXPORT_SYMBOL_GPL(fib_rules_dump);
+
+static void notify_rule_change(int event, struct fib_rule *rule,
+                              struct fib_rules_ops *ops)
+{
+       int size = nlmsg_total_size(sizeof(struct fib_rule_hdr) + 128);
+       struct sk_buff *skb = alloc_skb(size, GFP_KERNEL);
+
+       if (skb == NULL)
+               netlink_set_err(rtnl, 0, ops->nlgroup, ENOBUFS);
+       else if (fib_nl_fill_rule(skb, rule, 0, 0, event, 0, ops) < 0) {
+               kfree_skb(skb);
+               netlink_set_err(rtnl, 0, ops->nlgroup, EINVAL);
+       } else
+               netlink_broadcast(rtnl, skb, 0, ops->nlgroup, GFP_KERNEL);
+}
+
+static void attach_rules(struct list_head *rules, struct net_device *dev)
+{
+       struct fib_rule *rule;
+
+       list_for_each_entry(rule, rules, list) {
+               if (rule->ifindex == -1 &&
+                   strcmp(dev->name, rule->ifname) == 0)
+                       rule->ifindex = dev->ifindex;
+       }
+}
+
+static void detach_rules(struct list_head *rules, struct net_device *dev)
+{
+       struct fib_rule *rule;
+
+       list_for_each_entry(rule, rules, list)
+               if (rule->ifindex == dev->ifindex)
+                       rule->ifindex = -1;
+}
+
+
+static int fib_rules_event(struct notifier_block *this, unsigned long event,
+                           void *ptr)
+{
+       struct net_device *dev = ptr;
+       struct fib_rules_ops *ops;
+
+       ASSERT_RTNL();
+       rcu_read_lock();
+
+       switch (event) {
+       case NETDEV_REGISTER:
+               list_for_each_entry(ops, &rules_ops, list)
+                       attach_rules(ops->rules_list, dev);
+               break;
+
+       case NETDEV_UNREGISTER:
+               list_for_each_entry(ops, &rules_ops, list)
+                       detach_rules(ops->rules_list, dev);
+               break;
+       }
+
+       rcu_read_unlock();
+
+       return NOTIFY_DONE;
+}
+
+static struct notifier_block fib_rules_notifier = {
+       .notifier_call = fib_rules_event,
+};
+
+static int __init fib_rules_init(void)
+{
+       return register_netdevice_notifier(&fib_rules_notifier);
+}
+
+subsys_initcall(fib_rules_init);

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 30cc1ba..aa7cff2 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -49,6 +49,7 @@
 #include <net/udp.h>
 #include <net/sock.h>
 #include <net/pkt_sched.h>
+#include <net/fib_rules.h>
 #include <net/netlink.h>
 #ifdef CONFIG_NET_WIRELESS_RTNETLINK
 #include <linux/wireless.h>
@@ -103,7 +104,7 @@ static const int rtm_min[RTM_NR_FAMILIES] =
        [RTM_FAM(RTM_NEWADDR)]      = NLMSG_LENGTH(sizeof(struct ifaddrmsg)),
        [RTM_FAM(RTM_NEWROUTE)]     = NLMSG_LENGTH(sizeof(struct rtmsg)),
        [RTM_FAM(RTM_NEWNEIGH)]     = NLMSG_LENGTH(sizeof(struct ndmsg)),
-       [RTM_FAM(RTM_NEWRULE)]      = NLMSG_LENGTH(sizeof(struct rtmsg)),
+       [RTM_FAM(RTM_NEWRULE)]      = NLMSG_LENGTH(sizeof(struct fib_rule_hdr)),
        [RTM_FAM(RTM_NEWQDISC)]     = NLMSG_LENGTH(sizeof(struct tcmsg)),
        [RTM_FAM(RTM_NEWTCLASS)]    = NLMSG_LENGTH(sizeof(struct tcmsg)),
        [RTM_FAM(RTM_NEWTFILTER)]   = NLMSG_LENGTH(sizeof(struct tcmsg)),
@@ -120,7 +121,7 @@ static const int rta_max[RTM_NR_FAMILIES] =
        [RTM_FAM(RTM_NEWADDR)]      = IFA_MAX,
        [RTM_FAM(RTM_NEWROUTE)]     = RTA_MAX,
        [RTM_FAM(RTM_NEWNEIGH)]     = NDA_MAX,
-       [RTM_FAM(RTM_NEWRULE)]      = RTA_MAX,
+       [RTM_FAM(RTM_NEWRULE)]      = FRA_MAX,
        [RTM_FAM(RTM_NEWQDISC)]     = TCA_MAX,
        [RTM_FAM(RTM_NEWTCLASS)]    = TCA_MAX,
        [RTM_FAM(RTM_NEWTFILTER)]   = TCA_MAX,
@@ -757,6 +758,10 @@ static struct rtnetlink_link link_rtnetlink_table[RTM_NR_MSGTYPES] =
        [RTM_NEWNEIGH    - RTM_BASE] = { .doit   = neigh_add             },
        [RTM_DELNEIGH    - RTM_BASE] = { .doit   = neigh_delete          },
        [RTM_GETNEIGH    - RTM_BASE] = { .dumpit = neigh_dump_info       },
+#ifdef CONFIG_FIB_RULES
+       [RTM_NEWRULE     - RTM_BASE] = { .doit   = fib_nl_newrule        },
+       [RTM_DELRULE     - RTM_BASE] = { .doit   = fib_nl_delrule        },
+#endif
        [RTM_GETRULE     - RTM_BASE] = { .dumpit = rtnetlink_dump_all    },
        [RTM_GETNEIGHTBL - RTM_BASE] = { .dumpit = neightbl_dump_info    },
        [RTM_SETNEIGHTBL - RTM_BASE] = { .doit   = neightbl_set          },