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flow: Don't crash if guest attempts to connect to port 0

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Using a zero port on TCP or UDP is dubious, and we can't really deal with
forwarding such a flow within the constraints of the socket API.  Hence
we ASSERT()ed that we had non-zero ports in flow_hash().

The intention was to make sure that the protocol code sanitizes such ports
before completing a flow entry.  Unfortunately, flow_hash() is also called
on new packets to see if they have an existing flow, so the unsanitized
guest packet can crash passt with the assert.

Correct this by moving the assert from flow_hash() to flow_sidx_hash()
which is only used on entries already in the table, not on unsanitized
data.

Reported-by: Matt Hamilton <matt@thmail.io>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
David Gibson 2024-08-14 20:03:33 +10:00 committed by Stefano Brivio
parent baba284912
commit 61c0b0d0f1
1 changed files with 10 additions and 8 deletions
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18
flow.c
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@ -561,12 +561,6 @@ static uint64_t flow_hash(const struct ctx *c, uint8_t proto, uint8_t pif,
{
struct siphash_state state = SIPHASH_INIT(c->hash_secret);
/* For the hash table to work, we need complete endpoint information,
* and at least a forwarding port.
*/
ASSERT(pif != PIF_NONE && !inany_is_unspecified(&side->eaddr) &&
side->eport != 0 && side->fport != 0);
inany_siphash_feed(&state, &side->faddr);
inany_siphash_feed(&state, &side->eaddr);
@ -586,8 +580,16 @@ static uint64_t flow_hash(const struct ctx *c, uint8_t proto, uint8_t pif,
static uint64_t flow_sidx_hash(const struct ctx *c, flow_sidx_t sidx)
{
const struct flow_common *f = &flow_at_sidx(sidx)->f;
return flow_hash(c, FLOW_PROTO(f),
f->pif[sidx.sidei], &f->side[sidx.sidei]);
const struct flowside *side = &f->side[sidx.sidei];
uint8_t pif = f->pif[sidx.sidei];
/* For the hash table to work, entries must have complete endpoint
* information, and at least a forwarding port.
*/
ASSERT(pif != PIF_NONE && !inany_is_unspecified(&side->eaddr) &&
side->eport != 0 && side->fport != 0);
return flow_hash(c, FLOW_PROTO(f), pif, side);
}
/**