710 lines
20 KiB
C
710 lines
20 KiB
C
/*
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* Filters: utility functions
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*
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* Copyright 1998 Pavel Machek <pavel@ucw.cz>
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*
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* Can be freely distributed and used under the terms of the GNU GPL.
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*
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*/
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/**
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* DOC: Filters
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*
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* You can find sources of the filter language in |filter/|
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* directory. File |filter/config.Y| contains filter grammar and basically translates
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* the source from user into a tree of &f_inst structures. These trees are
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* later interpreted using code in |filter/filter.c|.
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*
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* A filter is represented by a tree of &f_inst structures, one structure per
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* "instruction". Each &f_inst contains @code, @aux value which is
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* usually the data type this instruction operates on and two generic
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* arguments (@a[0], @a[1]). Some instructions contain pointer(s) to other
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* instructions in their (@a[0], @a[1]) fields.
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*
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* Filters use a &f_val structure for their data. Each &f_val
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* contains type and value (types are constants prefixed with %T_). Few
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* of the types are special; %T_RETURN can be or-ed with a type to indicate
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* that return from a function or from the whole filter should be
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* forced. Important thing about &f_val's is that they may be copied
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* with a simple |=|. That's fine for all currently defined types: strings
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* are read-only (and therefore okay), paths are copied for each
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* operation (okay too).
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*/
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#undef LOCAL_DEBUG
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#include "nest/bird.h"
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#include "lib/lists.h"
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#include "lib/resource.h"
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#include "lib/socket.h"
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#include "lib/string.h"
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#include "lib/unaligned.h"
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#include "lib/net.h"
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#include "lib/ip.h"
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#include "nest/route.h"
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#include "nest/protocol.h"
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#include "nest/iface.h"
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#include "nest/attrs.h"
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#include "conf/conf.h"
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#include "filter/filter.h"
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#include "filter/f-inst.h"
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#include "filter/data.h"
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struct filter_stack {
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/* Value stack for execution */
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#define F_VAL_STACK_MAX 4096
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uint vcnt; /* Current value stack size; 0 for empty */
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uint ecnt; /* Current execute stack size; 0 for empty */
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struct f_val vstk[F_VAL_STACK_MAX]; /* The stack itself */
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/* Instruction stack for execution */
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#define F_EXEC_STACK_MAX 4096
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struct {
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const struct f_line *line; /* The line that is being executed */
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uint pos; /* Instruction index in the line */
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uint ventry; /* Value stack depth on entry */
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uint vbase; /* Where to index variable positions from */
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enum f_exception emask; /* Exception mask */
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} estk[F_EXEC_STACK_MAX];
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};
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/* Internal filter state, to be allocated on stack when executing filters */
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struct filter_state {
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/* Stacks needed for execution */
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struct filter_stack *stack;
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/* The route we are processing. This may be NULL to indicate no route available. */
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struct rte **rte;
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/* The old rta to be freed after filters are done. */
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struct rta *old_rta;
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/* Cached pointer to ea_list */
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struct ea_list **eattrs;
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/* Linpool for adata allocation */
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struct linpool *pool;
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/* Buffer for log output */
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struct buffer buf;
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/* Filter execution flags */
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int flags;
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};
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#if HAVE_THREAD_LOCAL
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_Thread_local static struct filter_state filter_state;
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_Thread_local static struct filter_stack filter_stack;
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#define FS_INIT(...) filter_state = (struct filter_state) { .stack = &filter_stack, __VA_ARGS__ }
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#else
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#define FS_INIT(...) struct filter_state filter_state = { .stack = alloca(sizeof(struct filter_stack)), __VA_ARGS__ };
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#endif
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void (*bt_assert_hook)(int result, const struct f_line_item *assert);
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static inline void f_cache_eattrs(struct filter_state *fs)
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{
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fs->eattrs = &((*fs->rte)->attrs->eattrs);
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}
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static inline void f_rte_cow(struct filter_state *fs)
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{
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if (!((*fs->rte)->flags & REF_COW))
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return;
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*fs->rte = rte_cow(*fs->rte);
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}
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/*
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* rta_cow - prepare rta for modification by filter
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*/
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static void
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f_rta_cow(struct filter_state *fs)
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{
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if (!rta_is_cached((*fs->rte)->attrs))
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return;
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/* Prepare to modify rte */
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f_rte_cow(fs);
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/* Store old rta to free it later, it stores reference from rte_cow() */
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fs->old_rta = (*fs->rte)->attrs;
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/*
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* Get shallow copy of rta. Fields eattrs and nexthops of rta are shared
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* with fs->old_rta (they will be copied when the cached rta will be obtained
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* at the end of f_run()), also the lock of hostentry is inherited (we
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* suppose hostentry is not changed by filters).
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*/
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(*fs->rte)->attrs = rta_do_cow((*fs->rte)->attrs, fs->pool);
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/* Re-cache the ea_list */
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f_cache_eattrs(fs);
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}
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static char *
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val_format_str(struct filter_state *fs, const struct f_val *v) {
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buffer b;
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LOG_BUFFER_INIT(b);
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val_format(v, &b);
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return lp_strdup(fs->pool, b.start);
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}
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static struct tbf rl_runtime_err = TBF_DEFAULT_LOG_LIMITS;
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#define runtime(fmt, ...) do { \
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if (!(fs->flags & FF_SILENT)) \
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log_rl(&rl_runtime_err, L_ERR "filters, line %d: " fmt, \
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(fs->stack->estk[fs->stack->ecnt-1].line->items[fs->stack->estk[fs->stack->ecnt-1].pos-1]).lineno, \
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##__VA_ARGS__); \
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return F_ERROR; \
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} while(0)
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#define ACCESS_RTE do { if (!fs->rte) runtime("No route to access"); } while (0)
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#define ACCESS_EATTRS do { if (!fs->eattrs) f_cache_eattrs(fs); } while (0)
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static inline enum filter_return
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f_rta_set(struct filter_state *fs, struct f_static_attr sa, const struct f_val *val)
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{
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ACCESS_RTE;
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if (sa.f_type != val->type)
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runtime( "Attempt to set static attribute to incompatible type" );
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f_rta_cow(fs);
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{
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struct rta *rta = (*fs->rte)->attrs;
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switch (sa.sa_code)
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{
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case SA_FROM:
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rta->from = val->val.ip;
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return F_NOP;
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case SA_GW:
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{
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ip_addr ip = val->val.ip;
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neighbor *n = neigh_find(rta->src->proto, ip, NULL, 0);
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if (!n || (n->scope == SCOPE_HOST))
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runtime( "Invalid gw address" );
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rta->dest = RTD_UNICAST;
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rta->nh.gw = ip;
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rta->nh.iface = n->iface;
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rta->nh.next = NULL;
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rta->hostentry = NULL;
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}
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return F_NOP;
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case SA_SCOPE:
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rta->scope = val->val.i;
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return F_NOP;
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case SA_DEST:
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{
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int i = val->val.i;
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if ((i != RTD_BLACKHOLE) && (i != RTD_UNREACHABLE) && (i != RTD_PROHIBIT))
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runtime( "Destination can be changed only to blackhole, unreachable or prohibit" );
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rta->dest = i;
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rta->nh.gw = IPA_NONE;
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rta->nh.iface = NULL;
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rta->nh.next = NULL;
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rta->hostentry = NULL;
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}
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return F_NOP;
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case SA_IFNAME:
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{
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struct iface *ifa = if_find_by_name(val->val.s);
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if (!ifa)
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runtime( "Invalid iface name" );
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rta->dest = RTD_UNICAST;
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rta->nh.gw = IPA_NONE;
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rta->nh.iface = ifa;
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rta->nh.next = NULL;
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rta->hostentry = NULL;
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}
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return F_NOP;
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default:
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bug("Invalid static attribute access (%u/%u)", sa.f_type, sa.sa_code);
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}
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}
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}
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static inline enum filter_return
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f_ea_set(struct filter_state *fs, struct f_dynamic_attr da, const struct f_val *val)
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{
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ACCESS_RTE;
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ACCESS_EATTRS;
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{
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struct ea_list *l = lp_alloc(fs->pool, sizeof(struct ea_list) + sizeof(eattr));
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l->next = NULL;
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l->flags = EALF_SORTED;
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l->count = 1;
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l->attrs[0].id = da.ea_code;
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l->attrs[0].flags = 0;
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l->attrs[0].type = da.type | EAF_ORIGINATED | EAF_FRESH;
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switch (da.type) {
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case EAF_TYPE_INT:
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if (val->type != da.f_type)
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runtime( "Setting int attribute to non-int value" );
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l->attrs[0].u.data = val->val.i;
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break;
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case EAF_TYPE_ROUTER_ID:
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/* IP->Quad implicit conversion */
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if (val_is_ip4(val)) {
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l->attrs[0].u.data = ipa_to_u32(val->val.ip);
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break;
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}
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/* T_INT for backward compatibility */
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if ((val->type != T_QUAD) && (val->type != T_INT))
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runtime( "Setting quad attribute to non-quad value" );
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l->attrs[0].u.data = val->val.i;
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break;
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case EAF_TYPE_OPAQUE:
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runtime( "Setting opaque attribute is not allowed" );
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break;
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case EAF_TYPE_IP_ADDRESS:
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if (val->type != T_IP)
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runtime( "Setting ip attribute to non-ip value" );
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int len = sizeof(ip_addr);
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struct adata *ad = lp_alloc(fs->pool, sizeof(struct adata) + len);
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ad->length = len;
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(* (ip_addr *) ad->data) = val->val.ip;
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l->attrs[0].u.ptr = ad;
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break;
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case EAF_TYPE_AS_PATH:
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if (val->type != T_PATH)
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runtime( "Setting path attribute to non-path value" );
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l->attrs[0].u.ptr = val->val.ad;
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break;
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case EAF_TYPE_BITFIELD:
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if (val->type != T_BOOL)
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runtime( "Setting bit in bitfield attribute to non-bool value" );
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{
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/* First, we have to find the old value */
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eattr *e = ea_find(*fs->eattrs, da.ea_code);
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u32 data = e ? e->u.data : 0;
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if (val->val.i)
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l->attrs[0].u.data = data | (1u << da.bit);
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else
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l->attrs[0].u.data = data & ~(1u << da.bit);
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}
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break;
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case EAF_TYPE_INT_SET:
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if (val->type != T_CLIST)
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runtime( "Setting clist attribute to non-clist value" );
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l->attrs[0].u.ptr = val->val.ad;
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break;
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case EAF_TYPE_EC_SET:
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if (val->type != T_ECLIST)
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runtime( "Setting eclist attribute to non-eclist value" );
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l->attrs[0].u.ptr = val->val.ad;
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break;
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case EAF_TYPE_LC_SET:
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if (val->type != T_LCLIST)
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runtime( "Setting lclist attribute to non-lclist value" );
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l->attrs[0].u.ptr = val->val.ad;
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break;
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default: bug("Unknown type in e,S");
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}
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f_rta_cow(fs);
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l->next = *fs->eattrs;
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*fs->eattrs = l;
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return F_NOP;
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}
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}
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static inline enum filter_return
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f_lval_set(struct filter_state *fs, const struct f_lval *lv, const struct f_val *val)
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{
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switch (lv->type) {
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case F_LVAL_STACK:
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fs->stack->vstk[fs->stack->vcnt] = *val;
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fs->stack->vcnt++;
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return F_NOP;
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case F_LVAL_EXCEPTION:
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{
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/* Drop every sub-block including ourselves */
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while ((fs->stack->ecnt-- > 0) && !(fs->stack->estk[fs->stack->ecnt].emask & lv->exception))
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;
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/* Now we are at the catch frame; if no such, try to convert to accept/reject. */
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if (!fs->stack->ecnt)
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if (lv->exception == FE_RETURN)
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if (val->type == T_BOOL)
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if (val->val.i)
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return F_ACCEPT;
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else
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return F_REJECT;
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else
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runtime("Can't return non-bool from non-function");
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else
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runtime("Unhandled exception 0x%x: %s", lv->exception, val_format_str(fs, val));
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/* Set the value stack position, overwriting the former implicit void */
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fs->stack->vcnt = fs->stack->estk[fs->stack->ecnt].ventry;
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/* Copy the return value */
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fs->stack->vstk[fs->stack->vcnt - 1] = *val;
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return F_NOP;
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}
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case F_LVAL_VARIABLE:
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fs->stack->vstk[fs->stack->estk[fs->stack->ecnt-1].vbase + lv->sym->offset] = *val;
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return F_NOP;
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case F_LVAL_PREFERENCE:
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ACCESS_RTE;
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if (val->type != T_INT)
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runtime("Preference must be integer, got 0x%02x", val->type);
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if (val->val.i > 0xFFFF)
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runtime("Preference is at most 65536");
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f_rte_cow(fs);
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(*fs->rte)->pref = val->val.i;
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return F_NOP;
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case F_LVAL_SA:
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return f_rta_set(fs, lv->sa, val);
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case F_LVAL_EA:
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return f_ea_set(fs, lv->da, val);
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default:
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bug("This shall never happen");
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}
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}
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/**
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* interpret
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* @fs: filter state
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* @what: filter to interpret
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*
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* Interpret given tree of filter instructions. This is core function
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* of filter system and does all the hard work.
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*
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* Each instruction has 4 fields: code (which is instruction code),
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* aux (which is extension to instruction code, typically type),
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* arg1 and arg2 - arguments. Depending on instruction, arguments
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* are either integers, or pointers to instruction trees. Common
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* instructions like +, that have two expressions as arguments use
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* TWOARGS macro to get both of them evaluated.
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*/
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static enum filter_return
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interpret(struct filter_state *fs, const struct f_line *line, struct f_val *val)
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{
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/* No arguments allowed */
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ASSERT(line->args == 0);
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/* Initialize the filter stack */
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struct filter_stack *fstk = fs->stack;
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fstk->vcnt = line->vars;
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memset(fstk->vstk, 0, sizeof(struct f_val) * line->vars);
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/* The same as with the value stack. Not resetting the stack for performance reasons. */
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fstk->ecnt = 1;
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fstk->estk[0].line = line;
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fstk->estk[0].pos = 0;
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#define curline fstk->estk[fstk->ecnt-1]
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#if DEBUGGING
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debug("Interpreting line.");
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f_dump_line(line, 1);
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#endif
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while (fstk->ecnt > 0) {
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while (curline.pos < curline.line->len) {
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const struct f_line_item *what = &(curline.line->items[curline.pos++]);
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switch (what->fi_code) {
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#define res fstk->vstk[fstk->vcnt]
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#define v1 fstk->vstk[fstk->vcnt]
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#define v2 fstk->vstk[fstk->vcnt + 1]
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#define v3 fstk->vstk[fstk->vcnt + 2]
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#include "filter/inst-interpret.c"
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#undef res
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#undef v1
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#undef v2
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#undef v3
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#undef runtime
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#undef ACCESS_RTE
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#undef ACCESS_EATTRS
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}
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}
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/* End of current line. Drop local variables before exiting. */
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fstk->vcnt -= curline.line->vars;
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fstk->vcnt -= curline.line->args;
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fstk->ecnt--;
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/* If the caller wants to store the result somewhere, do it. */
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if (fstk->ecnt) {
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const struct f_line_item *caller = &(curline.line->items[curline.pos-1]);
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if (caller->result.type != F_LVAL_STACK) {
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enum filter_return fret = f_lval_set(fs, &(caller->result), &fstk->vstk[--fstk->vcnt]);
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if (fret != F_NOP)
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return fret;
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}
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}
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}
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if (fstk->vcnt == 0) {
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if (val) {
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log_rl(&rl_runtime_err, L_ERR "filters: No value left on stack");
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return F_ERROR;
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}
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return F_NOP;
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}
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if (val && (fstk->vcnt == 1)) {
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*val = fstk->vstk[0];
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return F_NOP;
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}
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log_rl(&rl_runtime_err, L_ERR "Too many items left on stack: %u", fstk->vcnt);
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return F_ERROR;
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}
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/**
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* f_run - run a filter for a route
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* @filter: filter to run
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* @rte: route being filtered, may be modified
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* @tmp_pool: all filter allocations go from this pool
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* @flags: flags
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*
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* If filter needs to modify the route, there are several
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* posibilities. @rte might be read-only (with REF_COW flag), in that
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* case rw copy is obtained by rte_cow() and @rte is replaced. If
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* @rte is originally rw, it may be directly modified (and it is never
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* copied).
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*
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* The returned rte may reuse the (possibly cached, cloned) rta, or
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* (if rta was modified) contains a modified uncached rta, which
|
||
* uses parts allocated from @tmp_pool and parts shared from original
|
||
* rta. There is one exception - if @rte is rw but contains a cached
|
||
* rta and that is modified, rta in returned rte is also cached.
|
||
*
|
||
* Ownership of cached rtas is consistent with rte, i.e.
|
||
* if a new rte is returned, it has its own clone of cached rta
|
||
* (and cached rta of read-only source rte is intact), if rte is
|
||
* modified in place, old cached rta is possibly freed.
|
||
*/
|
||
enum filter_return
|
||
f_run(const struct filter *filter, struct rte **rte, struct linpool *tmp_pool, int flags)
|
||
{
|
||
if (filter == FILTER_ACCEPT)
|
||
return F_ACCEPT;
|
||
|
||
if (filter == FILTER_REJECT)
|
||
return F_REJECT;
|
||
|
||
int rte_cow = ((*rte)->flags & REF_COW);
|
||
DBG( "Running filter `%s'...", filter->name );
|
||
|
||
/* Initialize the filter state */
|
||
FS_INIT(
|
||
.rte = rte,
|
||
.pool = tmp_pool,
|
||
.flags = flags,
|
||
);
|
||
|
||
LOG_BUFFER_INIT(filter_state.buf);
|
||
|
||
/* Run the interpreter itself */
|
||
enum filter_return fret = interpret(&filter_state, filter->root, NULL);
|
||
|
||
if (filter_state.old_rta) {
|
||
/*
|
||
* Cached rta was modified and filter_state->rte contains now an uncached one,
|
||
* sharing some part with the cached one. The cached rta should
|
||
* be freed (if rte was originally COW, filter_state->old_rta is a clone
|
||
* obtained during rte_cow()).
|
||
*
|
||
* This also implements the exception mentioned in f_run()
|
||
* description. The reason for this is that rta reuses parts of
|
||
* filter_state->old_rta, and these may be freed during rta_free(filter_state->old_rta).
|
||
* This is not the problem if rte was COW, because original rte
|
||
* also holds the same rta.
|
||
*/
|
||
if (!rte_cow) {
|
||
/* Cache the new attrs */
|
||
(*filter_state.rte)->attrs = rta_lookup((*filter_state.rte)->attrs);
|
||
|
||
/* Drop cached ea_list pointer */
|
||
filter_state.eattrs = NULL;
|
||
}
|
||
|
||
/* Uncache the old attrs and drop the pointer as it is invalid now. */
|
||
rta_free(filter_state.old_rta);
|
||
filter_state.old_rta = NULL;
|
||
}
|
||
|
||
/* Process the filter output, log it and return */
|
||
if (fret < F_ACCEPT) {
|
||
if (!(filter_state.flags & FF_SILENT))
|
||
log_rl(&rl_runtime_err, L_ERR "Filter %s did not return accept nor reject. Make up your mind", filter_name(filter));
|
||
return F_ERROR;
|
||
}
|
||
DBG( "done (%u)\n", res.val.i );
|
||
return fret;
|
||
}
|
||
|
||
/**
|
||
* f_eval_rte – run a filter line for an uncached route
|
||
* @expr: filter line to run
|
||
* @rte: route being filtered, may be modified
|
||
* @tmp_pool: all filter allocations go from this pool
|
||
*
|
||
* This specific filter entry point runs the given filter line
|
||
* (which must not have any arguments) on the given route.
|
||
*
|
||
* The route MUST NOT have REF_COW set and its attributes MUST NOT
|
||
* be cached by rta_lookup().
|
||
*/
|
||
|
||
enum filter_return
|
||
f_eval_rte(const struct f_line *expr, struct rte **rte, struct linpool *tmp_pool)
|
||
{
|
||
FS_INIT(
|
||
.rte = rte,
|
||
.pool = tmp_pool,
|
||
);
|
||
|
||
LOG_BUFFER_INIT(filter_state.buf);
|
||
|
||
ASSERT(!((*rte)->flags & REF_COW));
|
||
ASSERT(!rta_is_cached((*rte)->attrs));
|
||
|
||
return interpret(&filter_state, expr, NULL);
|
||
}
|
||
|
||
/*
|
||
* f_eval – get a value of a term
|
||
* @expr: filter line containing the term
|
||
* @tmp_pool: long data may get allocated from this pool
|
||
* @pres: here the output will be stored
|
||
*/
|
||
enum filter_return
|
||
f_eval(const struct f_line *expr, struct linpool *tmp_pool, struct f_val *pres)
|
||
{
|
||
FS_INIT(
|
||
.pool = tmp_pool,
|
||
);
|
||
|
||
LOG_BUFFER_INIT(filter_state.buf);
|
||
|
||
enum filter_return fret = interpret(&filter_state, expr, pres);
|
||
return fret;
|
||
}
|
||
|
||
/*
|
||
* f_eval_int – get an integer value of a term
|
||
* Called internally from the config parser, uses its internal memory pool
|
||
* for allocations. Do not call in other cases.
|
||
*/
|
||
uint
|
||
f_eval_int(const struct f_line *expr)
|
||
{
|
||
/* Called independently in parse-time to eval expressions */
|
||
FS_INIT(
|
||
.pool = cfg_mem,
|
||
);
|
||
|
||
struct f_val val;
|
||
|
||
LOG_BUFFER_INIT(filter_state.buf);
|
||
|
||
if (interpret(&filter_state, expr, &val) > F_RETURN)
|
||
cf_error("Runtime error while evaluating expression");
|
||
|
||
if (val.type != T_INT)
|
||
cf_error("Integer expression expected");
|
||
|
||
return val.val.i;
|
||
}
|
||
|
||
/*
|
||
* f_eval_buf – get a value of a term and print it to the supplied buffer
|
||
*/
|
||
enum filter_return
|
||
f_eval_buf(const struct f_line *expr, struct linpool *tmp_pool, buffer *buf)
|
||
{
|
||
struct f_val val;
|
||
enum filter_return fret = f_eval(expr, tmp_pool, &val);
|
||
if (fret > F_RETURN)
|
||
val_format(&val, buf);
|
||
return fret;
|
||
}
|
||
|
||
/**
|
||
* filter_same - compare two filters
|
||
* @new: first filter to be compared
|
||
* @old: second filter to be compared
|
||
*
|
||
* Returns 1 in case filters are same, otherwise 0. If there are
|
||
* underlying bugs, it will rather say 0 on same filters than say
|
||
* 1 on different.
|
||
*/
|
||
int
|
||
filter_same(const struct filter *new, const struct filter *old)
|
||
{
|
||
if (old == new) /* Handle FILTER_ACCEPT and FILTER_REJECT */
|
||
return 1;
|
||
if (old == FILTER_ACCEPT || old == FILTER_REJECT ||
|
||
new == FILTER_ACCEPT || new == FILTER_REJECT)
|
||
return 0;
|
||
|
||
if ((!old->sym) && (!new->sym))
|
||
return f_same(new->root, old->root);
|
||
|
||
if ((!old->sym) || (!new->sym))
|
||
return 0;
|
||
|
||
if (strcmp(old->sym->name, new->sym->name))
|
||
return 0;
|
||
|
||
return new->sym->flags & SYM_FLAG_SAME;
|
||
}
|
||
|
||
/**
|
||
* filter_commit - do filter comparisons on all the named functions and filters
|
||
*/
|
||
void
|
||
filter_commit(const struct config *new, const struct config *old)
|
||
{
|
||
if (!old)
|
||
return;
|
||
|
||
struct symbol *sym, *osym;
|
||
WALK_LIST(sym, new->symbols)
|
||
switch (sym->class) {
|
||
case SYM_FUNCTION:
|
||
if ((osym = cf_find_symbol(old, sym->name)) &&
|
||
(osym->class == SYM_FUNCTION) &&
|
||
f_same(sym->function, osym->function))
|
||
sym->flags |= SYM_FLAG_SAME;
|
||
else
|
||
sym->flags &= ~SYM_FLAG_SAME;
|
||
break;
|
||
|
||
case SYM_FILTER:
|
||
if ((osym = cf_find_symbol(old, sym->name)) &&
|
||
(osym->class == SYM_FILTER) &&
|
||
f_same(sym->filter->root, osym->filter->root))
|
||
sym->flags |= SYM_FLAG_SAME;
|
||
else
|
||
sym->flags &= ~SYM_FLAG_SAME;
|
||
break;
|
||
}
|
||
}
|