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bird/proto/aggregator/aggregator.c
Maria Matejka 018a77fc0b Aggregator: Forbidden dangerous filter computations
2023-09-26 15:46:24 +02:00

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/*
* BIRD Internet Routing Daemon -- Route aggregation
*
* (c) 2023--2023 Igor Putovny <igor.putovny@nic.cz>
* (c) 2023 CZ.NIC, z.s.p.o.
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
/**
* DOC: Route aggregation
*
* This is an implementation of route aggregation functionality.
* It enables user to specify a set of route attributes in the configuarion file
* and then, for a given destination (net), aggregate routes with the same
* values of these attributes into a single multi-path route.
*
* Structure &channel contains pointer to aggregation list which is represented
* by &aggr_list_linearized. In rt_notify_aggregated(), attributes from this
* list are evaluated for every route of a given net and results are stored
* in &rte_val_list which contains pointer to this route and array of &f_val.
* Array of pointers to &rte_val_list entries is sorted using
* sort_rte_val_list(). For comparison of &f_val structures, val_compare()
* is used. Comparator function is written so that sorting is stable. If all
* attributes have the same values, routes are compared by their global IDs.
*
* After sorting, &rte_val_list entries containing equivalent routes will be
* adjacent to each other. Function process_rte_list() iterates through these
* entries to identify sequences of equivalent routes. New route will be
* created for each such sequence, even if only from a single route.
* Only attributes from the aggreagation list will be set for the new route.
* New &rta is created and prepare_rta() is used to copy static and dynamic
* attributes to new &rta from &rta of the original route. New route is created
* by create_merged_rte() from new &rta and exported to the routing table.
*/
#undef LOCAL_DEBUG
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include "nest/bird.h"
#include "nest/iface.h"
#include "filter/filter.h"
#include "aggregator.h"
#include <stdlib.h>
/*
#include "nest/route.h"
#include "nest/iface.h"
#include "lib/resource.h"
#include "lib/event.h"
#include "lib/timer.h"
#include "lib/string.h"
#include "conf/conf.h"
#include "filter/filter.h"
#include "filter/data.h"
#include "lib/hash.h"
#include "lib/string.h"
#include "lib/alloca.h"
#include "lib/flowspec.h"
*/
extern linpool *rte_update_pool;
/*
* Set static attribute in @rta from static attribute in @old according to @sa.
*/
static void
rta_set_static_attr(struct rta *rta, const struct rta *old, struct f_static_attr sa)
{
switch (sa.sa_code)
{
case SA_NET:
break;
case SA_FROM:
rta->from = old->from;
break;
case SA_GW:
rta->dest = RTD_UNICAST;
rta->nh.gw = old->nh.gw;
rta->nh.iface = old->nh.iface;
rta->nh.next = NULL;
rta->hostentry = NULL;
rta->nh.labels = 0;
break;
case SA_SCOPE:
rta->scope = old->scope;
break;
case SA_DEST:
rta->dest = old->dest;
rta->nh.gw = IPA_NONE;
rta->nh.iface = NULL;
rta->nh.next = NULL;
rta->hostentry = NULL;
rta->nh.labels = 0;
break;
case SA_IFNAME:
rta->dest = RTD_UNICAST;
rta->nh.gw = IPA_NONE;
rta->nh.iface = old->nh.iface;
rta->nh.next = NULL;
rta->hostentry = NULL;
rta->nh.labels = 0;
break;
case SA_GW_MPLS:
rta->nh.labels = old->nh.labels;
memcpy(&rta->nh.label, &old->nh.label, sizeof(u32) * old->nh.labels);
break;
case SA_WEIGHT:
rta->nh.weight = old->nh.weight;
break;
case SA_PREF:
rta->pref = old->pref;
break;
default:
bug("Invalid static attribute access (%u/%u)", sa.f_type, sa.sa_code);
}
}
/*
* Compare list of &f_val entries.
* @count: number of &f_val entries
*/
static int
same_val_list(const struct f_val *v1, const struct f_val *v2, uint len)
{
for (uint i = 0; i < len; i++)
if (!val_same(&v1[i], &v2[i]))
return 0;
return 1;
}
/*
* Create and export new merged route.
* @old: first route in a sequence of equivalent routes that are to be merged
* @rte_val: first element in a sequence of equivalent rte_val_list entries
* @length: number of equivalent routes that are to be merged (at least 1)
* @ail: aggregation list
*/
static void
aggregator_bucket_update(struct aggregator_proto *p, struct aggregator_bucket *bucket, struct network *net)
{
/* Empty bucket */
if (!bucket->rte)
{
rte_update2(p->dst, net->n.addr, NULL, bucket->last_src);
bucket->last_src = NULL;
return;
}
/* Allocate RTA and EA list */
struct rta *rta = allocz(rta_size(bucket->rte->attrs));
rta->dest = RTD_UNREACHABLE;
rta->source = RTS_AGGREGATED;
rta->scope = SCOPE_UNIVERSE;
struct ea_list *eal = allocz(sizeof(struct ea_list) + sizeof(struct eattr) * p->aggr_on_da_count);
eal->next = NULL;
eal->count = 0;
rta->eattrs = eal;
/* Seed the attributes from aggregator rule */
for (uint i = 0; i < p->aggr_on_count; i++)
{
if (p->aggr_on[i].type == AGGR_ITEM_DYNAMIC_ATTR)
{
u32 ea_code = p->aggr_on[i].da.ea_code;
const struct eattr *e = ea_find(bucket->rte->attrs->eattrs, ea_code);
if (e)
eal->attrs[eal->count++] = *e;
}
else if (p->aggr_on[i].type == AGGR_ITEM_STATIC_ATTR)
rta_set_static_attr(rta, bucket->rte->attrs, p->aggr_on[i].sa);
}
struct rte *new = rte_get_temp(rta, bucket->rte->src);
new->net = net;
/*
log("=============== CREATE MERGED ROUTE ===============");
log("New route created: id = %d, protocol: %s", new->src->global_id, new->src->proto->name);
log("===================================================");
*/
/* merge filter needs one argument called "routes" */
struct f_val val = {
.type = T_ROUTES_BLOCK,
.val.rte = bucket->rte,
};
/* Actually run the filter */
enum filter_return fret = f_eval_rte(p->merge_by, &new, rte_update_pool, 1, &val, 0);
/* Src must be stored now, rte_update2() may return new */
struct rte_src *new_src = new ? new->src : NULL;
/* Finally import the route */
switch (fret)
{
/* Pass the route to the protocol */
case F_ACCEPT:
rte_update2(p->dst, net->n.addr, new, bucket->last_src ?: new->src);
break;
/* Something bad happened */
default:
ASSERT_DIE(fret == F_ERROR);
/* fall through */
/* We actually don't want this route */
case F_REJECT:
if (bucket->last_src)
rte_update2(p->dst, net->n.addr, NULL, bucket->last_src);
break;
}
/* Switch source lock for bucket->last_src */
if (bucket->last_src != new_src)
{
if (new_src)
rt_lock_source(new_src);
if (bucket->last_src)
rt_unlock_source(bucket->last_src);
bucket->last_src = new_src;
}
}
/*
* Reload all the buckets on reconfiguration if merge filter has changed.
* TODO: make this splitted
*/
static void
aggregator_reload_buckets(void *data)
{
struct aggregator_proto *p = data;
HASH_WALK(p->buckets, next_hash, b)
if (b->rte)
{
aggregator_bucket_update(p, b, b->rte->net);
lp_flush(rte_update_pool);
}
HASH_WALK_END;
}
/*
* Evaluate static attribute of @rt1 according to @sa
* and store result in @pos.
*/
static void
eval_static_attr(const struct rte *rt1, struct f_static_attr sa, struct f_val *pos)
{
const struct rta *rta = rt1->attrs;
#define RESULT(_type, value, result) \
do { \
pos->type = _type; \
pos->val.value = result; \
} while (0)
switch (sa.sa_code)
{
case SA_NET: RESULT(sa.f_type, net, rt1->net->n.addr); break;
case SA_FROM: RESULT(sa.f_type, ip, rta->from); break;
case SA_GW: RESULT(sa.f_type, ip, rta->nh.gw); break;
case SA_PROTO: RESULT(sa.f_type, s, rt1->src->proto->name); break;
case SA_SOURCE: RESULT(sa.f_type, i, rta->source); break;
case SA_SCOPE: RESULT(sa.f_type, i, rta->scope); break;
case SA_DEST: RESULT(sa.f_type, i, rta->dest); break;
case SA_IFNAME: RESULT(sa.f_type, s, rta->nh.iface ? rta->nh.iface->name : ""); break;
case SA_IFINDEX: RESULT(sa.f_type, i, rta->nh.iface ? rta->nh.iface->index : 0); break;
case SA_WEIGHT: RESULT(sa.f_type, i, rta->nh.weight + 1); break;
case SA_PREF: RESULT(sa.f_type, i, rta->pref); break;
case SA_GW_MPLS: RESULT(sa.f_type, i, rta->nh.labels ? rta->nh.label[0] : MPLS_NULL); break;
default:
bug("Invalid static attribute access (%u/%u)", sa.f_type, sa.sa_code);
}
#undef RESULT
}
/*
* Evaluate dynamic attribute of @rt1 according to @da
* and store result in @pos.
*/
static void
eval_dynamic_attr(const struct rte *rt1, struct f_dynamic_attr da, struct f_val *pos)
{
const struct rta *rta = rt1->attrs;
const struct eattr *e = ea_find(rta->eattrs, da.ea_code);
#define RESULT(_type, value, result) \
do { \
pos->type = _type; \
pos->val.value = result; \
} while (0)
#define RESULT_VOID \
do { \
pos->type = T_VOID; \
} while (0)
if (!e)
{
/* A special case: undefined as_path looks like empty as_path */
if (da.type == EAF_TYPE_AS_PATH)
{
RESULT(T_PATH, ad, &null_adata);
return;
}
/* The same special case for int_set */
if (da.type == EAF_TYPE_INT_SET)
{
RESULT(T_CLIST, ad, &null_adata);
return;
}
/* The same special case for ec_set */
if (da.type == EAF_TYPE_EC_SET)
{
RESULT(T_ECLIST, ad, &null_adata);
return;
}
/* The same special case for lc_set */
if (da.type == EAF_TYPE_LC_SET)
{
RESULT(T_LCLIST, ad, &null_adata);
return;
}
/* Undefined value */
RESULT_VOID;
return;
}
switch (e->type & EAF_TYPE_MASK)
{
case EAF_TYPE_INT:
RESULT(da.f_type, i, e->u.data);
break;
case EAF_TYPE_ROUTER_ID:
RESULT(T_QUAD, i, e->u.data);
break;
case EAF_TYPE_OPAQUE:
RESULT(T_ENUM_EMPTY, i, 0);
break;
case EAF_TYPE_IP_ADDRESS:
RESULT(T_IP, ip, *((ip_addr *) e->u.ptr->data));
break;
case EAF_TYPE_AS_PATH:
RESULT(T_PATH, ad, e->u.ptr);
break;
case EAF_TYPE_BITFIELD:
RESULT(T_BOOL, i, !!(e->u.data & (1u << da.bit)));
break;
case EAF_TYPE_INT_SET:
RESULT(T_CLIST, ad, e->u.ptr);
break;
case EAF_TYPE_EC_SET:
RESULT(T_ECLIST, ad, e->u.ptr);
break;
case EAF_TYPE_LC_SET:
RESULT(T_LCLIST, ad, e->u.ptr);
break;
default:
bug("Unknown dynamic attribute type");
}
#undef RESULT
#undef RESULT_VOID
}
static inline u32 aggr_route_hash(const rte *e)
{
struct {
net *net;
struct rte_src *src;
} obj = {
.net = e->net,
.src = e->src,
};
return mem_hash(&obj, sizeof obj);
}
#define AGGR_RTE_KEY(n) (&(n)->rte)
#define AGGR_RTE_NEXT(n) ((n)->next_hash)
#define AGGR_RTE_EQ(a,b) (((a)->src == (b)->src) && ((a)->net == (b)->net))
#define AGGR_RTE_FN(_n) aggr_route_hash(_n)
#define AGGR_RTE_ORDER 4 /* Initial */
#define AGGR_RTE_REHASH aggr_rte_rehash
#define AGGR_RTE_PARAMS /8, *2, 2, 2, 4, 24
HASH_DEFINE_REHASH_FN(AGGR_RTE, struct aggregator_route);
#define AGGR_BUCK_KEY(n) (n)
#define AGGR_BUCK_NEXT(n) ((n)->next_hash)
#define AGGR_BUCK_EQ(a,b) (((a)->hash == (b)->hash) && (same_val_list((a)->aggr_data, (b)->aggr_data, p->aggr_on_count)))
#define AGGR_BUCK_FN(n) ((n)->hash)
#define AGGR_BUCK_ORDER 4 /* Initial */
#define AGGR_BUCK_REHASH aggr_buck_rehash
#define AGGR_BUCK_PARAMS /8, *2, 2, 2, 4, 24
HASH_DEFINE_REHASH_FN(AGGR_BUCK, struct aggregator_bucket);
#define AGGR_DATA_MEMSIZE (sizeof(struct f_val) * p->aggr_on_count)
static void
aggregator_rt_notify(struct proto *P, struct channel *src_ch, net *net, rte *new, rte *old)
{
struct aggregator_proto *p = SKIP_BACK(struct aggregator_proto, p, P);
ASSERT_DIE(src_ch == p->src);
struct aggregator_bucket *new_bucket = NULL, *old_bucket = NULL;
struct aggregator_route *old_route = NULL;
/* Find the objects for the old route */
if (old)
old_route = HASH_FIND(p->routes, AGGR_RTE, old);
if (old_route)
old_bucket = old_route->bucket;
/* Find the bucket for the new route */
if (new)
{
/* Routes are identical, do nothing */
if (old_route && rte_same(&old_route->rte, new))
return;
/* Evaluate route attributes. */
struct aggregator_bucket *tmp_bucket = sl_allocz(p->bucket_slab);
for (uint val_idx = 0; val_idx < p->aggr_on_count; val_idx++)
{
int type = p->aggr_on[val_idx].type;
struct f_val *pos = &tmp_bucket->aggr_data[val_idx];
switch (type)
{
case AGGR_ITEM_TERM: {
const struct f_line *line = p->aggr_on[val_idx].line;
struct rte *rt1 = new;
enum filter_return fret = f_eval_rte(line, &new, rte_update_pool, 0, NULL, pos);
if (rt1 != new)
{
rte_free(rt1);
log(L_WARN "Aggregator rule modifies the route, reverting");
}
if (fret > F_RETURN)
log(L_WARN "%s.%s: Wrong number of items left on stack after evaluation of aggregation list", rt1->src->proto->name, rt1->sender->name);
switch (pos->type) {
case T_VOID:
case T_INT:
case T_BOOL:
case T_PAIR:
case T_QUAD:
case T_ENUM:
case T_IP:
case T_EC:
case T_LC:
case T_RD:
/* Fits, OK */
break;
default:
log(L_WARN "%s.%s: Expression evaluated to type %s unsupported by aggregator. Store this value as a custom attribute instead", new->src->proto->name, new->sender->name, f_type_name(pos->type));
*pos = (struct f_val) { .type = T_INT, .val.i = 0 };
}
break;
}
case AGGR_ITEM_STATIC_ATTR: {
eval_static_attr(new, p->aggr_on[val_idx].sa, pos);
break;
}
case AGGR_ITEM_DYNAMIC_ATTR: {
eval_dynamic_attr(new, p->aggr_on[val_idx].da, pos);
break;
}
default:
break;
}
}
/* Compute the hash */
u64 haux;
mem_hash_init(&haux);
for (uint i = 0; i < p->aggr_on_count; i++)
{
mem_hash_mix_num(&haux, tmp_bucket->aggr_data[i].type);
#define MX(k) mem_hash_mix(&haux, &IT(k), sizeof IT(k));
#define IT(k) tmp_bucket->aggr_data[i].val.k
switch (tmp_bucket->aggr_data[i].type)
{
case T_VOID:
break;
case T_INT:
case T_BOOL:
case T_PAIR:
case T_QUAD:
case T_ENUM:
MX(i);
break;
case T_EC:
case T_RD:
MX(ec);
break;
case T_LC:
MX(lc);
break;
case T_IP:
MX(ip);
break;
case T_NET:
mem_hash_mix_num(&haux, net_hash(IT(net)));
break;
case T_STRING:
mem_hash_mix_str(&haux, IT(s));
break;
case T_PATH_MASK:
mem_hash_mix(&haux, IT(path_mask), sizeof(*IT(path_mask)) + IT(path_mask)->len * sizeof (IT(path_mask)->item));
break;
case T_PATH:
case T_CLIST:
case T_ECLIST:
case T_LCLIST:
case T_BYTESTRING:
mem_hash_mix(&haux, IT(ad)->data, IT(ad)->length);
break;
case T_NONE:
case T_PATH_MASK_ITEM:
case T_ROUTE:
case T_ROUTES_BLOCK:
bug("Invalid type %s in hashing", f_type_name(tmp_bucket->aggr_data[i].type));
case T_SET:
MX(t);
break;
case T_PREFIX_SET:
MX(ti);
break;
}
}
tmp_bucket->hash = mem_hash_value(&haux);
/* Find the existing bucket */
if (new_bucket = HASH_FIND(p->buckets, AGGR_BUCK, tmp_bucket))
sl_free(tmp_bucket);
else
{
new_bucket = tmp_bucket;
HASH_INSERT2(p->buckets, AGGR_BUCK, p->p.pool, new_bucket);
}
/* Store the route attributes */
if (rta_is_cached(new->attrs))
rta_clone(new->attrs);
else
new->attrs = rta_lookup(new->attrs);
/* Insert the new route into the bucket */
struct aggregator_route *arte = sl_alloc(p->route_slab);
*arte = (struct aggregator_route) {
.bucket = new_bucket,
.rte = *new,
};
arte->rte.next = new_bucket->rte,
new_bucket->rte = &arte->rte;
new_bucket->count++;
HASH_INSERT2(p->routes, AGGR_RTE, p->p.pool, arte);
}
/* Remove the old route from its bucket */
if (old_bucket)
{
for (struct rte **k = &old_bucket->rte; *k; k = &(*k)->next)
if (*k == &old_route->rte)
{
*k = (*k)->next;
break;
}
old_bucket->count--;
HASH_REMOVE2(p->routes, AGGR_RTE, p->p.pool, old_route);
rta_free(old_route->rte.attrs);
sl_free(old_route);
}
/* Announce changes */
if (old_bucket)
aggregator_bucket_update(p, old_bucket, net);
if (new_bucket && (new_bucket != old_bucket))
aggregator_bucket_update(p, new_bucket, net);
/* Cleanup the old bucket if empty */
if (old_bucket && (!old_bucket->rte || !old_bucket->count))
{
ASSERT_DIE(!old_bucket->rte && !old_bucket->count);
HASH_REMOVE2(p->buckets, AGGR_BUCK, p->p.pool, old_bucket);
sl_free(old_bucket);
}
}
static int
aggregator_preexport(struct channel *C, struct rte *new)
{
struct aggregator_proto *p = SKIP_BACK(struct aggregator_proto, p, C->proto);
/* Reject our own routes */
if (new->sender == p->dst)
return -1;
/* Disallow aggregating already aggregated routes */
if (new->attrs->source == RTS_AGGREGATED)
{
log(L_ERR "Multiple aggregations of the same route not supported in BIRD 2.");
return -1;
}
return 0;
}
static void
aggregator_postconfig(struct proto_config *CF)
{
struct aggregator_config *cf = SKIP_BACK(struct aggregator_config, c, CF);
if (!cf->dst->table)
cf_error("Source table not specified");
if (!cf->src->table)
cf_error("Destination table not specified");
if (cf->dst->table->addr_type != cf->src->table->addr_type)
cf_error("Both tables must be of the same type");
cf->dst->in_filter = cf->src->in_filter;
cf->src->in_filter = FILTER_REJECT;
cf->dst->out_filter = FILTER_REJECT;
cf->dst->debug = cf->src->debug;
}
static struct proto *
aggregator_init(struct proto_config *CF)
{
struct proto *P = proto_new(CF);
struct aggregator_proto *p = SKIP_BACK(struct aggregator_proto, p, P);
struct aggregator_config *cf = SKIP_BACK(struct aggregator_config, c, CF);
proto_configure_channel(P, &p->src, cf->src);
proto_configure_channel(P, &p->dst, cf->dst);
p->aggr_on_count = cf->aggr_on_count;
p->aggr_on_da_count = cf->aggr_on_da_count;
p->aggr_on = cf->aggr_on;
p->merge_by = cf->merge_by;
P->rt_notify = aggregator_rt_notify;
P->preexport = aggregator_preexport;
return P;
}
static int
aggregator_start(struct proto *P)
{
struct aggregator_proto *p = SKIP_BACK(struct aggregator_proto, p, P);
p->bucket_slab = sl_new(P->pool, sizeof(struct aggregator_bucket) + AGGR_DATA_MEMSIZE);
HASH_INIT(p->buckets, P->pool, AGGR_BUCK_ORDER);
p->route_slab = sl_new(P->pool, sizeof(struct aggregator_route));
HASH_INIT(p->routes, P->pool, AGGR_RTE_ORDER);
p->reload_buckets = (event) {
.hook = aggregator_reload_buckets,
.data = p,
};
return PS_UP;
}
static int
aggregator_shutdown(struct proto *P)
{
struct aggregator_proto *p = SKIP_BACK(struct aggregator_proto, p, P);
HASH_WALK_DELSAFE(p->buckets, next_hash, b)
{
while (b->rte)
{
struct aggregator_route *arte = SKIP_BACK(struct aggregator_route, rte, b->rte);
b->rte = arte->rte.next;
b->count--;
HASH_REMOVE(p->routes, AGGR_RTE, arte);
rta_free(arte->rte.attrs);
sl_free(arte);
}
ASSERT_DIE(b->count == 0);
HASH_REMOVE(p->buckets, AGGR_BUCK, b);
sl_free(b);
}
HASH_WALK_END;
return PS_DOWN;
}
static int
aggregator_reconfigure(struct proto *P, struct proto_config *CF)
{
struct aggregator_proto *p = SKIP_BACK(struct aggregator_proto, p, P);
struct aggregator_config *cf = SKIP_BACK(struct aggregator_config, c, CF);
TRACE(D_EVENTS, "Reconfiguring");
/* Compare numeric values (shortcut) */
if (cf->aggr_on_count != p->aggr_on_count)
return 0;
if (cf->aggr_on_da_count != p->aggr_on_da_count)
return 0;
/* Compare aggregator rule */
for (uint i = 0; i < p->aggr_on_count; i++)
switch (cf->aggr_on[i].type)
{
case AGGR_ITEM_TERM:
if (!f_same(cf->aggr_on[i].line, p->aggr_on[i].line))
return 0;
break;
case AGGR_ITEM_STATIC_ATTR:
if (memcmp(&cf->aggr_on[i].sa, &p->aggr_on[i].sa, sizeof(struct f_static_attr)) != 0)
return 0;
break;
case AGGR_ITEM_DYNAMIC_ATTR:
if (memcmp(&cf->aggr_on[i].da, &p->aggr_on[i].da, sizeof(struct f_dynamic_attr)) != 0)
return 0;
break;
default:
bug("Broken aggregator rule");
}
/* Compare merge filter */
if (!f_same(cf->merge_by, p->merge_by))
ev_schedule(&p->reload_buckets);
p->aggr_on = cf->aggr_on;
p->merge_by = cf->merge_by;
return 1;
}
struct protocol proto_aggregator = {
.name = "Aggregator",
.template = "aggregator%d",
.class = PROTOCOL_AGGREGATOR,
.preference = 1,
.channel_mask = NB_ANY,
.proto_size = sizeof(struct aggregator_proto),
.config_size = sizeof(struct aggregator_config),
.postconfig = aggregator_postconfig,
.init = aggregator_init,
.start = aggregator_start,
.shutdown = aggregator_shutdown,
.reconfigure = aggregator_reconfigure,
};
void
aggregator_build(void)
{
proto_build(&proto_aggregator);
}
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