Re: [PATCH v6 14/18] pesto: Read current ruleset from passt/pasta and optionally display it

On Mon, 4 May 2026 18:10:48 +0200 Laurent Vivier wrote:

On 5/3/26 23:55, Stefano Brivio wrote:

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From: David Gibson

Implement serialisation of our current forwarding rules in conf.c, deserialising it to display in the pesto client. Doing this requires adding ip.c, inany.c, bitmap.c, lineread.c and fwd_rule.c to the pesto build. With previous preparations that now requires only a trivial change to lineread.c.

Signed-off-by: David Gibson [sbrivio: Use ntohs() for rule->to instead of htons() in fwd_rule_read(), reported by Jon Maloy] Signed-off-by: Stefano Brivio

With the "pc->fwd.count <= MAX_FWD_RULES" check added below, add:

Reviewed-by: Laurent Vivier

More cosmetics nit below

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--- Makefile | 17 +++++++++++++---- conf.c | 12 +++++++++++- fwd_rule.c | 41 +++++++++++++++++++++++++++++++++++++++++ fwd_rule.h | 4 ++++ lineread.c | 2 +- pesto.c | 37 ++++++++++++++++++++++++++++++++++--- pesto.h | 6 ++++++ 7 files changed, 110 insertions(+), 9 deletions(-)

diff --git a/Makefile b/Makefile index 6da76b4..057e4eb 100644 --- a/Makefile +++ b/Makefile @@ -47,7 +47,7 @@ PASST_SRCS = arch.c arp.c bitmap.c checksum.c conf.c dhcp.c dhcpv6.c \ vhost_user.c virtio.c vu_common.c QRAP_SRCS = qrap.c PASST_REPAIR_SRCS = passt-repair.c -PESTO_SRCS = pesto.c serialise.c +PESTO_SRCS = pesto.c bitmap.c fwd_rule.c inany.c ip.c lineread.c serialise.c SRCS = $(PASST_SRCS) $(QRAP_SRCS) $(PASST_REPAIR_SRCS) $(PESTO_SRCS)

MANPAGES = passt.1 pasta.1 pesto.1 qrap.1 passt-repair.1 @@ -62,6 +62,8 @@ PASST_HEADERS = arch.h arp.h bitmap.h checksum.h common.h conf.h dhcp.h \ QRAP_HEADERS = arp.h ip.h passt.h util.h PASST_REPAIR_HEADERS = linux_dep.h PESTO_HEADERS = common.h pesto.h log.h serialise.h

Duplicate PESTO_HEADERS ^ v

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+PESTO_HEADERS = common.h pesto.h bitmap.h fwd_rule.h inany.h ip.h lineread.h \ + log.h serialise.h

Fixed in v7.

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C := \#include \nint main(){int a=getrandom(0, 0, 0);} ifeq ($(shell printf "$(C)" | $(CC) -S -xc - -o - >/dev/null 2>&1; echo $$?),0) @@ -223,15 +225,22 @@ cppcheck: passt.cppcheck passt-repair.cppcheck pesto.cppcheck qrap.cppcheck $(CPPCHECK) $(CPPCHECK_FLAGS) $(BASE_CPPFLAGS) $^

passt.cppcheck: BASE_CPPFLAGS += -UPESTO -passt.cppcheck: CPPCHECK_FLAGS += --suppress=unusedFunction:serialise.c +passt.cppcheck: CPPCHECK_FLAGS += \ + --suppress=unusedFunction:fwd_rule.c \ + --suppress=unusedFunction:serialise.c passt.cppcheck: $(PASST_SRCS) $(PASST_HEADERS) seccomp.h

passt-repair.cppcheck: $(PASST_REPAIR_SRCS) $(PASST_REPAIR_HEADERS) seccomp_repair.h

pesto.cppcheck: BASE_CPPFLAGS += -DPESTO pesto.cppcheck: CPPCHECK_FLAGS += \ - --suppress=unusedFunction:serialise.c \ - --suppress=staticFunction:serialise.c + --suppress=unusedFunction:bitmap.c \ + --suppress=unusedFunction:inany.h \ + --suppress=unusedFunction:inany.c \ + --suppress=unusedFunction:ip.h \ + --suppress=unusedFunction:fwd_rule.c \ + --suppress=staticFunction:fwd_rule.c \ + --suppress=unusedFunction:serialise.c pesto.cppcheck: $(PESTO_SRCS) $(PESTO_HEADERS) seccomp_pesto.h

qrap.cppcheck: BASE_CPPFLAGS += -DARCH=\"$(TARGET_ARCH)\" diff --git a/conf.c b/conf.c index 3b2fe42..5e4e81e 100644 --- a/conf.c +++ b/conf.c @@ -1939,21 +1939,30 @@ static int conf_send_rules(const struct ctx *c, int fd) unsigned pif;

for (pif = 0; pif < PIF_NUM_TYPES; pif++) { + struct fwd_table *fwd = c->fwd[pif]; struct pesto_pif_info info; + unsigned i; int rc;

- if (!c->fwd[pif]) + if (!fwd) continue;

assert(pif != PIF_NONE);

rc = snprintf(info.name, sizeof(info.name), "%s", pif_name(pif)); assert(rc >= 0 && (size_t)rc < sizeof(info.name)); + info.caps = htonl(fwd->caps); + info.count = htonl(fwd->count);

if (write_u8(fd, pif) < 0) return -1; if (write_all_buf(fd, &info, sizeof(info)) < 0) return -1; + + for (i = 0; i < fwd->count; i++) { + if (fwd_rule_write(fd, &fwd->rules[i])) + return -1; + } }

if (write_u8(fd, PIF_NONE) < 0) @@ -2006,6 +2015,7 @@ static void conf_accept(struct ctx *c) .magic = PESTO_SERVER_MAGIC, .version = htonl(PESTO_PROTOCOL_VERSION), .pif_name_size = htonl(PIF_NAME_SIZE), + .ifnamsiz = htonl(IFNAMSIZ), }; union epoll_ref ref = { .type = EPOLL_TYPE_CONF }; struct ucred uc = { 0 }; diff --git a/fwd_rule.c b/fwd_rule.c index 7fd20dd..da9d893 100644 --- a/fwd_rule.c +++ b/fwd_rule.c @@ -24,6 +24,7 @@ #include "fwd_rule.h" #include "lineread.h" #include "log.h" +#include "serialise.h"

/* Ephemeral port range: values from RFC 6335 */ static in_port_t fwd_ephemeral_min = (1 << 15) + (1 << 14); @@ -645,3 +646,43 @@ void fwd_rule_parse(char optname, const char *optarg, struct fwd_table *fwd)

fwd_rule_parse_ports(fwd, proto, addr, ifname, spec); } + + +/** + * fwd_rule_read() - Read serialised rule from an fd + * @fd: fd to serialise to

should be "fd to deserialise from" (or something like that)

Changed in v7 like you suggested.

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+ * @rule: Buffer to store rule into + * + * Return: 0 on success, -1 on error (with errno set) + */ +int fwd_rule_read(int fd, struct fwd_rule *rule) +{ + if (read_all_buf(fd, rule, sizeof(*rule))) + return -1; + + /* Byteswap for host */ + rule->first = ntohs(rule->first); + rule->last = ntohs(rule->last); + rule->to = ntohs(rule->to); + + return 0; +} + +/** + * fwd_rule_write() - Serialise rule to an fd + * @fd: fd to serialise to + * @rule: Rule to send + * + * Return: 0 on success, -1 on error (with errno set) + */ +int fwd_rule_write(int fd, const struct fwd_rule *rule) +{ + struct fwd_rule tmp = *rule; + + /* Byteswap for transport */ + tmp.first = htons(tmp.first); + tmp.last = htons(tmp.last); + tmp.to = htons(tmp.to); + + return write_all_buf(fd, &tmp, sizeof(tmp)); +} diff --git a/fwd_rule.h b/fwd_rule.h index f51f1b4..330d49e 100644 --- a/fwd_rule.h +++ b/fwd_rule.h @@ -29,6 +29,8 @@ #define FWD_CAP_UDP BIT(3) #define FWD_CAP_SCAN BIT(4) #define FWD_CAP_IFNAME BIT(5) +#define FWD_CAP_ALL (FWD_CAP_IPV4 | FWD_CAP_IPV6 | FWD_CAP_TCP | \ + FWD_CAP_UDP | FWD_CAP_SCAN | FWD_CAP_IFNAME)

/** * struct fwd_rule - Forwarding rule governing a range of ports @@ -99,6 +101,8 @@ void fwd_probe_ephemeral(void); const union inany_addr *fwd_rule_addr(const struct fwd_rule *rule); const char *fwd_rule_fmt(const struct fwd_rule *rule, char *dst, size_t size); void fwd_rule_parse(char optname, const char *optarg, struct fwd_table *fwd); +int fwd_rule_read(int fd, struct fwd_rule *rule); +int fwd_rule_write(int fd, const struct fwd_rule *rule);

/** * fwd_rules_dump() - Dump forwarding rules diff --git a/lineread.c b/lineread.c index b9ceae1..a4269a6 100644 --- a/lineread.c +++ b/lineread.c @@ -19,8 +19,8 @@ #include #include

+#include "common.h" #include "lineread.h" -#include "util.h"

/** * lineread_init() - Prepare for line by line file reading without allocation diff --git a/pesto.c b/pesto.c index 77244b3..4bf9bd8 100644 --- a/pesto.c +++ b/pesto.c @@ -34,6 +34,7 @@ #include "common.h" #include "seccomp_pesto.h" #include "serialise.h" +#include "fwd_rule.h" #include "pesto.h" #include "log.h"

@@ -66,6 +67,7 @@ static void usage(const char *name, FILE *f, int status) struct pif_configuration { uint8_t pif; char name[PIF_NAME_SIZE]; + struct fwd_table fwd; };

struct configuration { @@ -123,6 +125,7 @@ static bool read_pif_conf(int fd, struct configuration *conf) struct pif_configuration *pc; struct pesto_pif_info info; uint8_t pif; + unsigned i;

if (read_u8(fd, &pif) < 0) die("Error reading from control socket"); @@ -151,8 +154,17 @@ static bool read_pif_conf(int fd, struct configuration *conf) static_assert(sizeof(info.name) == sizeof(pc->name), "Mismatching pif name lengths"); memcpy(pc->name, info.name, sizeof(pc->name)); - - debug("PIF %"PRIu8": %s", pc->pif, pc->name); + pc->fwd.caps = ntohl(info.caps); + pc->fwd.count = ntohl(info.count);

We should check that pc->fwd.count <= MAX_FWD_RULES to avoid overflow while scanning the array.

Oops, fixed in v7. I missed it as I wasn't really focusing on pesto being robust, but curiously Coverity Scan missed it as well... weird.

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+ + debug("PIF %"PRIu8": %s, %"PRIu32" rules, capabilities 0x%"PRIx32 + ":%s%s%s%s%s%s", pc->pif, pc->name, pc->fwd.count, pc->fwd.caps, + pc->fwd.caps & FWD_CAP_IPV4 ? " IPv4" : "", + pc->fwd.caps & FWD_CAP_IPV6 ? " IPv6" : "", + pc->fwd.caps & FWD_CAP_TCP ? " TCP" : "", + pc->fwd.caps & FWD_CAP_UDP ? " UDP" : "", + pc->fwd.caps & FWD_CAP_SCAN ? " scan" : "", + pc->fwd.caps & FWD_CAP_IFNAME ? " ifname" : "");

/* O(n^2), but n is bounded by MAX_PIFS */ if (pif_conf_by_num(conf, pc->pif)) @@ -162,6 +174,18 @@ static bool read_pif_conf(int fd, struct configuration *conf) if (pif_conf_by_name(conf, pc->name)) die("Received duplicate interface name");

+ /* NOTE: We read the fwd rules directly into fwd.rules, rather than + * using fwd_rule_add(). This means we can read and display rules even + * if something has gone wrong (in pesto or passt) and we get rules that + * fwd_rule_add() would reject. It does have the side effect that we + * never assign socket space for the fwd rules, but we don't need that + * within pesto. + */ + for (i = 0; i < pc->fwd.count; i++) { + if (fwd_rule_read(fd, &pc->fwd.rules[i]) < 0) + die("Error reading from control socket"); + } + conf->npifs++; return true; } @@ -177,7 +201,8 @@ static void show_conf(const struct configuration *conf) for (i = 0; i < conf->npifs; i++) { const struct pif_configuration *pc = &conf->pif[i]; printf(" %s\n", pc->name); - printf(" TBD\n"); + fwd_rules_dump(printf, pc->fwd.rules, pc->fwd.count, + " ", "\n"); } }

@@ -290,6 +315,12 @@ int main(int argc, char **argv) ntohl(hello.pif_name_size), PIF_NAME_SIZE); }

+ if (ntohl(hello.ifnamsiz) != IFNAMSIZ) { + die("Server has unexpected IFNAMSIZ (%" + PRIu32" not %"PRIu32"\n",

trailing '\n'

Fixed in v7, and I also added the missing ")".

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+ ntohl(hello.ifnamsiz), IFNAMSIZ); + } +

Trailing tab :)

Fixed in v7.

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while (read_pif_conf(s, &conf)) ;

diff --git a/pesto.h b/pesto.h index 1879759..12b0b65 100644 --- a/pesto.h +++ b/pesto.h @@ -26,11 +26,13 @@ * @magic: PESTO_SERVER_MAGIC * @version: Version number * @pif_name_size: Server's value for PIF_NAME_SIZE + * @ifnamsiz: Server's value for IFNAMSIZ */ struct pesto_hello { char magic[8]; uint32_t version; uint32_t pif_name_size; + uint32_t ifnamsiz; } __attribute__ ((__packed__));

static_assert(sizeof(PESTO_SERVER_MAGIC) @@ -40,9 +42,13 @@ static_assert(sizeof(PESTO_SERVER_MAGIC) /** * struct pesto_pif_info - Message with basic metadata about a pif * @name: Name (\0 terminated) + * @caps: Forwarding capabilities for this pif + * @count: Number of forwarding rules for this pif */ struct pesto_pif_info { char name[PIF_NAME_SIZE]; + uint32_t caps; + uint32_t count; } __attribute__ ((__packed__));

#endif /* PESTO_H */

-- Stefano