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From: David Gibson <david@gibson.dropbear.id.au>
To: passt-dev@passt.top, Stefano Brivio <sbrivio@redhat.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Subject: [PATCH 13/16] util: Correct sock_l4() binding for link local addresses
Date: Wed, 14 Aug 2024 14:30:47 +1000	[thread overview]
Message-ID: <20240814043050.4177037-14-david@gibson.dropbear.id.au> (raw)
In-Reply-To: <20240814043050.4177037-1-david@gibson.dropbear.id.au>

When binding an IPv6 socket in sock_l4() we need to supply a scope id if
the address is link-local.  We check for this by comparing the given
address to c->ip6.addr_ll.  This is correct only by accident: while
c->ip6.addr_ll is typically set to the hsot interface's link local
address, the actually purpose of it is to provide a link local address
for passt's private use on the tap interface.

Instead set the scope id for any link-local address we're binding to.
We're going to need something and this is what makes sense for sockets
on the host.  It doesn't make sense for PIF_SPLICE sockets, but those
should always have loopback, not link-local addresses.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 util.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/util.c b/util.c
index 892358b1..9682e3ce 100644
--- a/util.c
+++ b/util.c
@@ -199,8 +199,7 @@ int sock_l4(const struct ctx *c, sa_family_t af, enum epoll_type type,
 		if (bind_addr) {
 			addr6.sin6_addr = *(struct in6_addr *)bind_addr;
 
-			if (!memcmp(bind_addr, &c->ip6.addr_ll,
-			    sizeof(c->ip6.addr_ll)))
+			if (IN6_IS_ADDR_LINKLOCAL(bind_addr))
 				addr6.sin6_scope_id = c->ifi6;
 		}
 		return sock_l4_sa(c, type, &addr6, sizeof(addr6), ifname,
-- 
@@ -199,8 +199,7 @@ int sock_l4(const struct ctx *c, sa_family_t af, enum epoll_type type,
 		if (bind_addr) {
 			addr6.sin6_addr = *(struct in6_addr *)bind_addr;
 
-			if (!memcmp(bind_addr, &c->ip6.addr_ll,
-			    sizeof(c->ip6.addr_ll)))
+			if (IN6_IS_ADDR_LINKLOCAL(bind_addr))
 				addr6.sin6_scope_id = c->ifi6;
 		}
 		return sock_l4_sa(c, type, &addr6, sizeof(addr6), ifname,
-- 
2.46.0


  parent reply	other threads:[~2024-08-14  4:31 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-08-14  4:30 [PATCH 00/16] Cleanups and fixes related to "our" addresses David Gibson
2024-08-14  4:30 ` [PATCH 01/16] conf: Don't ignore -t and -u options after -D David Gibson
2024-08-14 12:18   ` Stefano Brivio
2024-08-14  4:30 ` [PATCH 02/16] treewide: Use "our address" instead of "forwarding address" David Gibson
2024-08-14  4:30 ` [PATCH 03/16] util: Helper for formatting MAC addresses David Gibson
2024-08-14  4:30 ` [PATCH 04/16] treewide: Rename MAC address fields for clarity David Gibson
2024-08-14  4:30 ` [PATCH 05/16] treewide: Use struct assignment instead of memcpy() for IP addresses David Gibson
2024-08-14  4:30 ` [PATCH 06/16] conf: Use array indices rather than pointers for DNS array slots David Gibson
2024-08-14  4:30 ` [PATCH 07/16] conf: More accurately count entries added in get_dns() David Gibson
2024-08-14  4:30 ` [PATCH 08/16] conf: Move DNS array bounds checks into add_dns[46] David Gibson
2024-08-14  4:30 ` [PATCH 09/16] conf: Move adding of a nameserver from resolv.conf into subfunction David Gibson
2024-08-14  4:30 ` [PATCH 10/16] conf: Correct setting of dns_match address in add_dns6() David Gibson
2024-08-14  4:30 ` [PATCH 11/16] conf: Treat --dns addresses as guest visible addresses David Gibson
2024-08-14  4:30 ` [PATCH 12/16] conf: Remove incorrect initialisation of addr_ll_seen David Gibson
2024-08-14  4:30 ` David Gibson [this message]
2024-08-14  4:30 ` [PATCH 14/16] treewide: Change misleading 'addr_ll' name David Gibson
2024-08-14  4:30 ` [PATCH 15/16] Clarify which addresses in ip[46]_ctx are meaningful where David Gibson
2024-08-14  4:30 ` [PATCH 16/16] Initialise our_tap_ll to ip6.gw when suitable David Gibson
2024-08-14  4:39   ` David Gibson
2024-08-14  5:03 ` [PATCH 00/16] Cleanups and fixes related to "our" addresses David Gibson

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