Re: [PATCH v5 17/18] pesto, conf: Send updated rules from pesto back to passt/pasta

On 2026-04-21 02:25, David Gibson wrote:

Extend pesto to send the updated rule configuration back to passt/pasta. Extend passt/pasta to read the new configuration and store the new rules in a "pending" table. We don't yet attempt to activate them.

Signed-off-by: Stefano Brivio Message-ID: <20260322141843.4095972-3-sbrivio@redhat.com> [dwg: Based on an early draft from Stefano]\ Signed-off-by: David Gibson

[...]

+/** + * conf_recv_rules() - Receive forwarding rules from configuration client + * @c: Execution context + * @fd: Socket to the client + * + * Return: 0 on success, -1 on failure + */ +static int conf_recv_rules(const struct ctx *c, int fd) +{ + while (1) { + struct fwd_table *fwd; + struct fwd_rule r; + uint32_t count; + uint8_t pif; + unsigned i; + + if (read_u8(fd, &pif)) + return -1; + + if (pif == PIF_NONE) + break; + + if (pif >= ARRAY_SIZE(c->fwd_pending) || + !(fwd = c->fwd_pending[pif])) { + err("Received rules for non-existent table"); + return -1; + } + + if (read_u32(fd, &count)) + return -1; + + if (count > MAX_FWD_RULES) { + err("Received %"PRIu32" rules (maximum %u)", + count, MAX_FWD_RULES); + return -1; + } + + for (i = 0; i < count; i++) { + fwd_rule_read(fd, &r);

Since we don't check the return value I think we risk passing an only partially initialized fwd_rule to fwd_rule_add() if the read fails. Maybe: if (fwd_rule_read(fd, &r)) return -1; /jon

+ if (fwd_rule_add(fwd, &r) < 0) + return -1; + } + } + + return 0; +} + /** * conf_close() - Close configuration / control socket and clean up * @c: Execution context @@ -2072,21 +2119,33 @@ fail: void conf_handler(struct ctx *c, uint32_t events) { if (events & EPOLLIN) { - char discard[BUFSIZ]; - ssize_t n; - - do { - n = read(c->fd_control, discard, sizeof(discard)); - if (n > 0) - debug("Discarded %zd bytes of config data", n); - } while (n > 0); - if (n == 0) { - debug("Configuration client EOF"); - goto close; + unsigned pif; + + /* Clear pending tables */ + for (pif = 0; pif < PIF_NUM_TYPES; pif++) { + struct fwd_table *fwd = c->fwd_pending[pif]; + + if (!fwd) + continue; + fwd->count = 0; + fwd->sock_count = 0; } - if (errno != EAGAIN && errno != EWOULDBLOCK) { - err_perror("Error reading config data"); + + /* FIXME: this could block indefinitely if the client doesn't + * write as much as it should + */ + if (conf_recv_rules(c, c->fd_control) < 0) goto close; + + for (pif = 0; pif < PIF_NUM_TYPES; pif++) { + struct fwd_table *fwd = c->fwd_pending[pif]; + + if (!fwd) + continue; + + info("New forwarding rules for %s:", pif_name(pif)); + fwd_rules_dump(info, fwd->rules, fwd->count, + " ", ""); } }

diff --git a/fwd.c b/fwd.c index 8849cfcd..d93d2e5d 100644 --- a/fwd.c +++ b/fwd.c @@ -247,6 +247,9 @@ void fwd_neigh_table_init(const struct ctx *c) static struct fwd_table fwd_in; static struct fwd_table fwd_out;

+static struct fwd_table fwd_in_pending; +static struct fwd_table fwd_out_pending; + /** * fwd_rule_init() - Initialise forwarding tables * @c: Execution context @@ -269,10 +272,15 @@ void fwd_rule_init(struct ctx *c) caps |= FWD_CAP_IFNAME;

fwd_in.caps = fwd_out.caps = caps; + fwd_in_pending.caps = fwd_out_pending.caps = caps;

c->fwd[PIF_HOST] = &fwd_in; - if (c->mode == MODE_PASTA) + c->fwd_pending[PIF_HOST] = &fwd_in_pending; + + if (c->mode == MODE_PASTA) { c->fwd[PIF_SPLICE] = &fwd_out; + c->fwd_pending[PIF_SPLICE] = &fwd_out_pending; + } }

/** diff --git a/passt.h b/passt.h index b3f049de..1726965d 100644 --- a/passt.h +++ b/passt.h @@ -188,6 +188,7 @@ struct ip6_ctx { * @pasta_ifi: Index of namespace interface for pasta * @pasta_conf_ns: Configure namespace after creating it * @fwd: Forwarding tables + * @fwd_pending: Pending forward tables * @no_tcp: Disable TCP operation * @tcp: Context for TCP protocol handler * @no_udp: Disable UDP operation @@ -270,6 +271,7 @@ struct ctx { int pasta_conf_ns;

struct fwd_table *fwd[PIF_NUM_TYPES]; + struct fwd_table *fwd_pending[PIF_NUM_TYPES];

int no_tcp; struct tcp_ctx tcp; diff --git a/pesto.c b/pesto.c index ebac6bd6..c6c595a4 100644 --- a/pesto.c +++ b/pesto.c @@ -225,6 +225,39 @@ static bool read_pif_conf(int fd, struct configuration *conf) return true; }

+/** + * send_conf() - Send updated configuration to passt/pasta + * @fd: Control socket + * @conf: Updated configuration + */ +static void send_conf(int fd, const struct configuration *conf) +{ + unsigned i; + + for (i = 0; i < conf->npifs; i++) { + const struct pif_configuration *pc = &conf->pif[i]; + unsigned j; + + if (write_u8(fd, pc->pif) < 0) + goto fail; + + if (write_u32(fd, pc->fwd.count) < 0) + goto fail; + + for (j = 0; j < pc->fwd.count; j++) { + if (fwd_rule_write(fd, &pc->fwd.rules[j]) < 0) + goto fail; + } + } + + if (write_u8(fd, PIF_NONE) < 0) + goto fail; + return; + +fail: + die_perror("Error writing to control socket"); +} + /** * show_conf() - Show current configuration obtained from passt/pasta * @conf: Configuration description @@ -427,6 +460,8 @@ int main(int argc, char **argv) show_conf(&conf); }

+ send_conf(s, &conf); + noupdate: if (shutdown(s, SHUT_RDWR) < 0 || close(s) < 0) die_perror("Error shutting down control socket");