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BGP: Use reallocation for capability structure

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Instead of having large stack buffer for max amount of AFI/SAFI pairs.
The old code is not correct w.r.t. extendeded option length, as more
AFI/SAFI pairs may fit into the capability option.
This commit is contained in:
Ondrej Zajicek (work) 2019-08-21 17:16:08 +02:00
parent 524d253853
commit 4fa0e472cf
2 changed files with 30 additions and 16 deletions
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2
lib/bitops.h
View file

@ -29,4 +29,6 @@ static inline u32 u32_hash(u32 v) { return v * 2902958171u; }
static inline u8 u32_popcount(u32 v) { return __builtin_popcount(v); } static inline u8 u32_popcount(u32 v) { return __builtin_popcount(v); }
static inline int uint_is_pow2(uint n) { return n && !(n & (n-1)); }
#endif #endif

44
proto/bgp/packets.c
View file

@ -185,14 +185,20 @@ bgp_find_af_caps(struct bgp_caps *caps, u32 afi)
} }
static struct bgp_af_caps * static struct bgp_af_caps *
bgp_get_af_caps(struct bgp_caps *caps, u32 afi) bgp_get_af_caps(struct bgp_caps **pcaps, u32 afi)
{ {
struct bgp_caps *caps = *pcaps;
struct bgp_af_caps *ac; struct bgp_af_caps *ac;
WALK_AF_CAPS(caps, ac) WALK_AF_CAPS(caps, ac)
if (ac->afi == afi) if (ac->afi == afi)
return ac; return ac;
uint n = caps->af_count;
if (uint_is_pow2(n))
*pcaps = caps = mb_realloc(caps, sizeof(struct bgp_caps) +
(2 * n) * sizeof(struct bgp_af_caps));
ac = &caps->af_data[caps->af_count++]; ac = &caps->af_data[caps->af_count++];
memset(ac, 0, sizeof(struct bgp_af_caps)); memset(ac, 0, sizeof(struct bgp_af_caps));
ac->afi = afi; ac->afi = afi;
@ -412,13 +418,22 @@ bgp_write_capabilities(struct bgp_conn *conn, byte *buf)
} }
static int static int
bgp_read_capabilities(struct bgp_conn *conn, struct bgp_caps *caps, byte *pos, int len) bgp_read_capabilities(struct bgp_conn *conn, byte *pos, int len)
{ {
struct bgp_proto *p = conn->bgp; struct bgp_proto *p = conn->bgp;
struct bgp_caps *caps;
struct bgp_af_caps *ac; struct bgp_af_caps *ac;
int i, cl; int i, cl;
u32 af; u32 af;
if (!conn->remote_caps)
caps = mb_allocz(p->p.pool, sizeof(struct bgp_caps) + sizeof(struct bgp_af_caps));
else
{
caps = conn->remote_caps;
conn->remote_caps = NULL;
}
caps->length += len; caps->length += len;
while (len > 0) while (len > 0)
@ -437,7 +452,7 @@ bgp_read_capabilities(struct bgp_conn *conn, struct bgp_caps *caps, byte *pos, i
goto err; goto err;
af = get_af4(pos+2); af = get_af4(pos+2);
ac = bgp_get_af_caps(caps, af); ac = bgp_get_af_caps(&caps, af);
ac->ready = 1; ac->ready = 1;
break; break;
@ -460,7 +475,7 @@ bgp_read_capabilities(struct bgp_conn *conn, struct bgp_caps *caps, byte *pos, i
continue; continue;
af = get_af4(pos+2+i); af = get_af4(pos+2+i);
ac = bgp_get_af_caps(caps, af); ac = bgp_get_af_caps(&caps, af);
ac->ext_next_hop = 1; ac->ext_next_hop = 1;
} }
break; break;
@ -490,7 +505,7 @@ bgp_read_capabilities(struct bgp_conn *conn, struct bgp_caps *caps, byte *pos, i
for (i = 2; i < cl; i += 4) for (i = 2; i < cl; i += 4)
{ {
af = get_af3(pos+2+i); af = get_af3(pos+2+i);
ac = bgp_get_af_caps(caps, af); ac = bgp_get_af_caps(&caps, af);
ac->gr_able = 1; ac->gr_able = 1;
ac->gr_af_flags = pos[2+i+3]; ac->gr_af_flags = pos[2+i+3];
} }
@ -522,7 +537,7 @@ bgp_read_capabilities(struct bgp_conn *conn, struct bgp_caps *caps, byte *pos, i
for (i = 0; i < cl; i += 4) for (i = 0; i < cl; i += 4)
{ {
af = get_af3(pos+2+i); af = get_af3(pos+2+i);
ac = bgp_get_af_caps(caps, af); ac = bgp_get_af_caps(&caps, af);
ac->add_path = pos[2+i+3]; ac->add_path = pos[2+i+3];
} }
break; break;
@ -551,7 +566,7 @@ bgp_read_capabilities(struct bgp_conn *conn, struct bgp_caps *caps, byte *pos, i
for (i = 0; i < cl; i += 7) for (i = 0; i < cl; i += 7)
{ {
af = get_af3(pos+2+i); af = get_af3(pos+2+i);
ac = bgp_get_af_caps(caps, af); ac = bgp_get_af_caps(&caps, af);
ac->llgr_able = 1; ac->llgr_able = 1;
ac->llgr_flags = pos[2+i+3]; ac->llgr_flags = pos[2+i+3];
ac->llgr_time = get_u24(pos + 2+i+4); ac->llgr_time = get_u24(pos + 2+i+4);
@ -577,9 +592,11 @@ bgp_read_capabilities(struct bgp_conn *conn, struct bgp_caps *caps, byte *pos, i
} }
} }
conn->remote_caps = caps;
return 0; return 0;
err: err:
mb_free(caps);
bgp_error(conn, 2, 0, NULL, 0); bgp_error(conn, 2, 0, NULL, 0);
return -1; return -1;
} }
@ -624,7 +641,6 @@ static int
bgp_read_options(struct bgp_conn *conn, byte *pos, uint len, uint rest) bgp_read_options(struct bgp_conn *conn, byte *pos, uint len, uint rest)
{ {
struct bgp_proto *p = conn->bgp; struct bgp_proto *p = conn->bgp;
struct bgp_caps *caps;
int ext = 0; int ext = 0;
/* Handle extended length (draft-ietf-idr-ext-opt-param-07) */ /* Handle extended length (draft-ietf-idr-ext-opt-param-07) */
@ -644,10 +660,6 @@ bgp_read_options(struct bgp_conn *conn, byte *pos, uint len, uint rest)
if (len > rest) if (len > rest)
goto err; goto err;
/* Max number of announced AFIs is limited by max option length (255) */
caps = alloca(sizeof(struct bgp_caps) + 64 * sizeof(struct bgp_af_caps));
memset(caps, 0, sizeof(struct bgp_caps));
/* Length of option parameter header */ /* Length of option parameter header */
uint hlen = ext ? 3 : 2; uint hlen = ext ? 3 : 2;
@ -666,7 +678,7 @@ bgp_read_options(struct bgp_conn *conn, byte *pos, uint len, uint rest)
{ {
/* BGP capabilities, RFC 5492 */ /* BGP capabilities, RFC 5492 */
if (p->cf->capabilities) if (p->cf->capabilities)
if (bgp_read_capabilities(conn, caps, pos + hlen, olen) < 0) if (bgp_read_capabilities(conn, pos + hlen, olen) < 0)
return -1; return -1;
} }
else else
@ -679,9 +691,9 @@ bgp_read_options(struct bgp_conn *conn, byte *pos, uint len, uint rest)
ADVANCE(pos, len, hlen + olen); ADVANCE(pos, len, hlen + olen);
} }
uint n = sizeof(struct bgp_caps) + caps->af_count * sizeof(struct bgp_af_caps); /* Prepare empty caps if no capability option was announced */
conn->remote_caps = mb_allocz(p->p.pool, n); if (!conn->remote_caps)
memcpy(conn->remote_caps, caps, n); conn->remote_caps = mb_allocz(p->p.pool, sizeof(struct bgp_caps));
return 0; return 0;