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network/ndisc: use the first captive portal in each RA

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To handle malicious RA packets gracefully.

Also prompted by https://github.com/systemd/systemd/pull/28285#issuecomment-1627585140.
This commit is contained in:
Yu Watanabe
2023-08-24 20:01:08 +09:00
parent bf943a9d49
commit 6df82d128c
1 changed files with 14 additions and 4 deletions
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src/network/networkd-ndisc.c
+14 -4
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@@ -900,21 +900,21 @@ static int ndisc_router_process_captive_portal(Link *link, sd_ndisc_router *rt)
return log_link_warning_errno(link, r, "Failed to get captive portal from RA: %m");
if (len == 0)
return 0;
return log_link_warning_errno(link, SYNTHETIC_ERRNO(EBADMSG), "Received empty captive portal, ignoring.");
r = make_cstring(uri, len, MAKE_CSTRING_REFUSE_TRAILING_NUL, &captive_portal);
if (r < 0)
return log_link_warning_errno(link, r, "Failed to convert captive portal URI: %m");
if (!in_charset(captive_portal, URI_VALID))
return log_link_debug_errno(link, SYNTHETIC_ERRNO(EBADMSG), "Received invalid captive portal, ignoring.");
return log_link_warning_errno(link, SYNTHETIC_ERRNO(EBADMSG), "Received invalid captive portal, ignoring.");
exist = set_get(link->ndisc_captive_portals, &(NDiscCaptivePortal) { .captive_portal = captive_portal });
if (exist) {
/* update existing entry */
exist->router = router;
exist->lifetime_usec = lifetime_usec;
return 0;
return 1;
}
if (set_size(link->ndisc_captive_portals) >= NDISC_CAPTIVE_PORTAL_MAX) {
@@ -947,10 +947,11 @@ static int ndisc_router_process_captive_portal(Link *link, sd_ndisc_router *rt)
TAKE_PTR(new_entry);
link_dirty(link);
return 0;
return 1;
}
static int ndisc_router_process_options(Link *link, sd_ndisc_router *rt) {
size_t n_captive_portal = 0;
int r;
assert(link);
@@ -986,7 +987,16 @@ static int ndisc_router_process_options(Link *link, sd_ndisc_router *rt) {
r = ndisc_router_process_dnssl(link, rt);
break;
case SD_NDISC_OPTION_CAPTIVE_PORTAL:
if (n_captive_portal > 0) {
if (n_captive_portal == 1)
log_link_notice(link, "Received RA with multiple captive portals, only using the first one.");
n_captive_portal++;
continue;
}
r = ndisc_router_process_captive_portal(link, rt);
if (r > 0)
n_captive_portal++;
break;
}
if (r < 0 && r != -EBADMSG)