net-misc/bird: BGP: fix locking order error

6779e5da69

Signed-off-by: Alarig Le Lay <alarig@swordarmor.fr>

metadata/md5-cache/net-misc/bird-3.0.0

@@ -11,4 +11,4 @@ RDEPEND=client? ( sys-libs/ncurses:= sys-libs/readline:= ) filecaps? ( acct-grou
 SLOT=0
 SRC_URI=ftp://bird.network.cz/pub/bird/bird-3.0.0.tar.gz
 _eclasses_=gnuconfig	ddeb9f8caff1b5f71a09c75b7534df79	toolchain-funcs	fa554cc3cff825d21dfe3f24841e29cf	multilib	b2a329026f2e404e9e371097dda47f96	libtool	6b28392a775f807c8be5fc7ec9a605b9	autotools	7d91cc798a8afd8f4e0c6e9587296ebe	fcaps	27152c9e4da035accb14a2d7879744ef
-_md5_=12cc3ec227c021ad52ded63dd738a74c
+_md5_=4dbfc03e077fb153238552e205be0ea5

net-misc/bird/bird-3.0.0.ebuild

@@ -38,6 +38,7 @@ FILECAPS=(
 
 PATCHES=(
 	"${FILESDIR}"/${P}-nest-rt-table.c.patch
+	"${FILESDIR}"/${P}-proto-lock.patch
 )
 
 src_prepare() {

net-misc/bird/files/bird-3.0.0-proto-lock.patch

@@ -0,0 +1,176 @@
+From 6779e5da698feb9b9e02411859ad81885ba46c01 Mon Sep 17 00:00:00 2001
+From: Maria Matejka <mq@ucw.cz>
+Date: Fri, 20 Dec 2024 11:28:00 +0100
+Subject: [PATCH] BGP: fix locking order error on dynamic protocol spawn
+
+We missed that the protocol spawner violates the prescribed
+locking order. When the rtable level is locked, no new protocol can be
+started, thus we need to:
+
+* create the protocol from a clean mainloop context
+* in protocol start hook, take the socket
+
+Testsuite: cf-bgp-autopeer
+Fixes: #136
+
+Thanks to Job Snijders <job@fastly.com> for reporting:
+https://trubka.network.cz/pipermail/bird-users/2024-December/017980.html
+---
+ nest/proto.c    | 19 +++++++++++++++++++
+ nest/protocol.h |  2 ++
+ proto/bgp/bgp.c | 46 +++++++++++++++++++++++++++++++++++-----------
+ 3 files changed, 56 insertions(+), 11 deletions(-)
+
+diff --git a/nest/proto.c b/nest/proto.c
+index dded84f51..678697d69 100644
+--- a/nest/proto.c
++++ b/nest/proto.c
+@@ -1867,6 +1867,25 @@ proto_spawn(struct proto_config *cf, uint disabled)
+   return p;
+ }
+ 
++bool
++proto_disable(struct proto *p)
++{
++  ASSERT_DIE(birdloop_inside(&main_birdloop));
++  bool changed = !p->disabled;
++  p->disabled = 1;
++  proto_rethink_goal(p);
++  return changed;
++}
++
++bool
++proto_enable(struct proto *p)
++{
++  ASSERT_DIE(birdloop_inside(&main_birdloop));
++  bool changed = p->disabled;
++  p->disabled = 0;
++  proto_rethink_goal(p);
++  return changed;
++}
+ 
+ /**
+  * DOC: Graceful restart recovery
+diff --git a/nest/protocol.h b/nest/protocol.h
+index 25ed6f553..cf7ecb898 100644
+--- a/nest/protocol.h
++++ b/nest/protocol.h
+@@ -78,6 +78,8 @@ void proto_build(struct protocol *);	/* Called from protocol to register itself
+ void protos_preconfig(struct config *);
+ void protos_commit(struct config *new, struct config *old, int type);
+ struct proto * proto_spawn(struct proto_config *cf, uint disabled);
++bool proto_disable(struct proto *p);
++bool proto_enable(struct proto *p);
+ void protos_dump_all(struct dump_request *);
+ 
+ #define GA_UNKNOWN	0		/* Attribute not recognized */
+diff --git a/proto/bgp/bgp.c b/proto/bgp/bgp.c
+index 5fc2b5fff..3170e3a42 100644
+--- a/proto/bgp/bgp.c
++++ b/proto/bgp/bgp.c
+@@ -378,8 +378,6 @@ bgp_startup(struct bgp_proto *p)
+   if (p->postponed_sk)
+   {
+     /* Apply postponed incoming connection */
+-    sk_reloop(p->postponed_sk, p->p.loop);
+-
+     bgp_setup_conn(p, &p->incoming_conn);
+     bgp_setup_sk(&p->incoming_conn, p->postponed_sk);
+     bgp_send_open(&p->incoming_conn);
+@@ -583,6 +581,9 @@ bgp_graceful_close_conn(struct bgp_conn *conn, int subcode, byte *data, uint len
+ static void
+ bgp_down(struct bgp_proto *p)
+ {
++  /* Check that the dynamic BGP socket has been picked up */
++  ASSERT_DIE(p->postponed_sk == NULL);
++
+   if (bgp_start_state(p) > BSS_PREPARE)
+   {
+     bgp_setup_auth(p, 0);
+@@ -617,8 +618,8 @@ bgp_decision(void *vp)
+     bgp_down(p);
+ }
+ 
+-static struct bgp_proto *
+-bgp_spawn(struct bgp_proto *pp, ip_addr remote_ip)
++static void
++bgp_spawn(struct bgp_proto *pp, struct birdsock *sk)
+ {
+   struct symbol *sym;
+   char fmt[SYM_MAX_LEN];
+@@ -635,9 +636,16 @@ bgp_spawn(struct bgp_proto *pp, ip_addr remote_ip)
+   cfg_mem = NULL;
+ 
+   /* Just pass remote_ip to bgp_init() */
+-  ((struct bgp_config *) sym->proto)->remote_ip = remote_ip;
++  ((struct bgp_config *) sym->proto)->remote_ip = sk->daddr;
++
++  /* Create the protocol disabled initially */
++  SKIP_BACK_DECLARE(struct bgp_proto, p, p, proto_spawn(sym->proto, 1));
+ 
+-  return (void *) proto_spawn(sym->proto, 0);
++  /* Pass the socket */
++  p->postponed_sk = sk;
++
++  /* And enable the protocol */
++  proto_enable(&p->p);
+ }
+ 
+ void
+@@ -1489,10 +1497,15 @@ bgp_incoming_connection(sock *sk, uint dummy UNUSED)
+   /* For dynamic BGP, spawn new instance and postpone the socket */
+   if (bgp_is_dynamic(p))
+   {
+-    p = bgp_spawn(p, sk->daddr);
+-    p->postponed_sk = sk;
+-    rmove(sk, p->p.pool);
+-    goto leave;
++    UNLOCK_DOMAIN(rtable, bgp_listen_domain);
++
++    /* The dynamic protocol must be in the START state */
++    ASSERT_DIE(p->p.proto_state == PS_START);
++    birdloop_leave(p->p.loop);
++
++    /* Now we have a clean mainloop */
++    bgp_spawn(p, sk);
++    return 0;
+   }
+ 
+   rmove(sk, p->p.pool);
+@@ -1806,7 +1819,6 @@ bgp_start(struct proto *P)
+   p->incoming_conn.state = BS_IDLE;
+   p->neigh = NULL;
+   p->bfd_req = NULL;
+-  p->postponed_sk = NULL;
+   p->gr_ready = 0;
+   p->gr_active_num = 0;
+ 
+@@ -1848,6 +1860,16 @@ bgp_start(struct proto *P)
+       channel_graceful_restart_lock(&c->c);
+   }
+ 
++  /* Now it's the last chance to move the postponed socket to this BGP,
++   * as bgp_start is the only hook running from main loop. */
++  if (p->postponed_sk)
++  {
++    LOCK_DOMAIN(rtable, bgp_listen_domain);
++    rmove(p->postponed_sk, p->p.pool);
++    sk_reloop(p->postponed_sk, p->p.loop);
++    UNLOCK_DOMAIN(rtable, bgp_listen_domain);
++  }
++
+   /*
+    * Before attempting to create the connection, we need to lock the port,
+    * so that we are the only instance attempting to talk with that neighbor.
+@@ -1999,6 +2021,8 @@ bgp_init(struct proto_config *CF)
+   p->remote_ip = cf->remote_ip;
+   p->remote_as = cf->remote_as;
+ 
++  p->postponed_sk = NULL;
++
+   /* Hack: We use cf->remote_ip just to pass remote_ip from bgp_spawn() */
+   if (cf->c.parent)
+     cf->remote_ip = IPA_NONE;
+-- 
+GitLab
+