git: df70662f4704 - stable/15 - rc: Teach netwait to wait for DAD
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Date: Thu, 09 Oct 2025 12:21:29 UTC
The branch stable/15 has been updated by des:
URL: https://cgit.FreeBSD.org/src/commit/?id=df70662f4704f432b00b5a8b4acd7f12a2deffa3
commit df70662f4704f432b00b5a8b4acd7f12a2deffa3
Author: Dag-Erling Smørgrav <des@FreeBSD.org>
AuthorDate: 2025-10-02 09:28:05 +0000
Commit: Dag-Erling Smørgrav <des@FreeBSD.org>
CommitDate: 2025-10-09 12:16:04 +0000
rc: Teach netwait to wait for DAD
In some configurations, especially in jails, it is possible for the
system to boot so fast that we end up launching daemons while duplicate
address detection is still ongoing. If that happens, said daemons may
fail to bind to IPv6 addresses, as they are still tentative. Teach the
netwait service to wait (up to 10 seconds, by default) for the tentative
flag to vanish.
MFC after: 1 week
Reviewed by: olce
Differential Revision: https://reviews.freebsd.org/D51889
(cherry picked from commit 5ead817c3b7af6d6b5fea222ab144db2c3167b22)
rc: Improve netwait DAD logic
Disable if IPv6 is not supported, and instead of 10 seconds, default to
one more than the value of net.inet6.ip6.dad_count.
Fixes: 5ead817c3b7a ("rc: Teach netwait to wait for DAD")
Reviewed by: bz
Differential Revision: https://reviews.freebsd.org/D52905
(cherry picked from commit ec6ad605ecea5c4a76d2e744df0265cc3f3a01b9)
---
libexec/rc/rc.conf | 3 ++
libexec/rc/rc.d/netwait | 86 ++++++++++++++++++++++++++++++++++--------------
share/man/man5/rc.conf.5 | 27 ++++++++++-----
3 files changed, 84 insertions(+), 32 deletions(-)
diff --git a/libexec/rc/rc.conf b/libexec/rc/rc.conf
index 9da2aef44d3d..96dd420d0322 100644
--- a/libexec/rc/rc.conf
+++ b/libexec/rc/rc.conf
@@ -500,6 +500,9 @@ netwait_enable="NO" # Enable rc.d/netwait (or NO)
netwait_timeout="60" # Total number of seconds to perform pings.
#netwait_if="" # Wait for active link on each intf in this list.
netwait_if_timeout="30" # Total number of seconds to monitor link state.
+netwait_dad="NO" # Wait for DAD to complete
+netwait_dad_timeout="" # Total number of seconds to wait for DAD, zero
+ # or unset to autodetect
### Miscellaneous network options: ###
icmp_bmcastecho="NO" # respond to broadcast ping packets
diff --git a/libexec/rc/rc.d/netwait b/libexec/rc/rc.d/netwait
index 3f374806d97c..05874552cf1c 100755
--- a/libexec/rc/rc.d/netwait
+++ b/libexec/rc/rc.d/netwait
@@ -2,12 +2,14 @@
#
# PROVIDE: netwait
# REQUIRE: devd ipfw pf routing
-# KEYWORD: nojail
#
-# The netwait script helps handle two situations:
+# The netwait script helps handle three situations:
# - Systems with USB or other late-attaching network hardware which
# is initialized by devd events. The script waits for all the
# interfaces named in the netwait_if list to appear.
+# - Systems with IPv6 addresses, especially jails, where we need to
+# wait for DAD to complete before starting daemons, as they will
+# otherwise fail to bind to IN6ADDR_ANY.
# - Systems with statically-configured IP addresses in rc.conf(5).
# The IP addresses in the netwait_ip list are pinged. The script
# waits for any single IP in the list to respond to the ping. If your
@@ -29,28 +31,38 @@ netwait_start()
{
local ip rc count output link wait_if got_if any_error
- if [ -z "${netwait_if}" ] && [ -z "${netwait_ip}" ]; then
- err 1 "No interface or IP addresses listed, nothing to wait for"
+ if [ -z "${netwait_if}" ] && [ -z "${netwait_ip}" ] &&
+ ! checkyesno netwait_dad ; then
+ err 1 "Nothing to wait for"
fi
- if [ ${netwait_timeout} -lt 1 ]; then
+ if ! [ "${netwait_if_timeout:=0}" -ge 1 ]; then
+ err 1 "netwait_if_timeout must be >= 1"
+ fi
+ if ! check_kern_features inet6; then
+ netwait_dad="NO"
+ elif ! [ "${netwait_dad_timeout:=0}" -ge 1 ]; then
+ netwait_dad_timeout=$(($(sysctl -n net.inet6.ip6.dad_count)+1))
+ fi
+ if ! [ "${netwait_timeout:=0}" -ge 1 ]; then
err 1 "netwait_timeout must be >= 1"
fi
+ any_error=false
+
if [ -n "${netwait_if}" ]; then
- any_error=0
for wait_if in ${netwait_if}; do
echo -n "Waiting for ${wait_if}"
link=""
- got_if=0
+ got_if=false
count=1
- # Handle SIGINT (Ctrl-C); force abort of while() loop
+ # Handle SIGINT (Ctrl-C); force abort of while loop
trap break SIGINT
while [ ${count} -le ${netwait_if_timeout} ]; do
if output=`/sbin/ifconfig ${wait_if} 2>/dev/null`; then
- if [ ${got_if} -eq 0 ]; then
+ if ! ${got_if}; then
echo -n ", interface present"
- got_if=1
+ got_if=true
fi
link=`expr "${output}" : '.*[[:blank:]]status: \(no carrier\)'`
if [ -z "${link}" ]; then
@@ -63,22 +75,45 @@ netwait_start()
done
# Restore default SIGINT handler
trap - SIGINT
- if [ ${got_if} -eq 0 ]; then
+ if ! ${got_if}; then
echo ", wait failed: interface never appeared."
- any_error=1
+ any_error=true
elif [ -n "${link}" ]; then
echo ", wait failed: interface still has no link."
- any_error=1
+ any_error=true
fi
done
- if [ ${any_error} -eq 1 ]; then
- warn "Continuing with startup, but be aware you may not have "
- warn "a fully functional networking layer at this point."
- fi
fi
+ if checkyesno netwait_dad; then
+ got_dad=false
+ # Handle SIGINT (Ctrl-C); force abort of while loop
+ trap break SIGINT
+
+ echo -n "Waiting for DAD to complete"
+ count=1
+ while [ ${count} -le ${netwait_dad_timeout} ]; do
+ if ! ifconfig | grep -q 'inet6.*tentative'; then
+ echo ', done.'
+ got_dad=true
+ break
+ fi
+ sleep 1
+ count=$((count+1))
+ done
+
+ # Restore default SIGINT handler
+ trap - SIGINT
+
+ if ! ${got_dad}; then
+ echo ', timed out.'
+ any_error=true
+ fi
+ fi
+
if [ -n "${netwait_ip}" ]; then
- # Handle SIGINT (Ctrl-C); force abort of for() loop
+ got_ip=false
+ # Handle SIGINT (Ctrl-C); force abort of for loop
trap break SIGINT
for ip in ${netwait_ip}; do
@@ -90,11 +125,9 @@ netwait_start()
rc=$?
if [ $rc -eq 0 ]; then
- # Restore default SIGINT handler
- trap - SIGINT
-
echo ', got response.'
- return
+ got_ip=false
+ break 2
fi
count=$((count+1))
done
@@ -104,10 +137,15 @@ netwait_start()
# Restore default SIGINT handler
trap - SIGINT
- warn "Exhausted IP list. Continuing with startup, but be aware you may"
- warn "not have a fully functional networking layer at this point."
+ if ! ${got_ip}; then
+ any_error=true
+ fi
fi
+ if ${any_error}; then
+ warn "Continuing with startup, but be aware you may not have "
+ warn "a fully functional networking layer at this point."
+ fi
}
load_rc_config $name
diff --git a/share/man/man5/rc.conf.5 b/share/man/man5/rc.conf.5
index b8c72fc07083..edbfa937f8df 100644
--- a/share/man/man5/rc.conf.5
+++ b/share/man/man5/rc.conf.5
@@ -22,7 +22,7 @@
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
-.Dd September 25, 2025
+.Dd October 5, 2025
.Dt RC.CONF 5
.Os
.Sh NAME
@@ -4563,20 +4563,16 @@ If set to
.Dq Li YES ,
delays the start of network-reliant services until
.Va netwait_if
-is up and ICMP packets to a destination defined in
+is up, duplicate address discovery (DAD) has completed, and ICMP
+packets to a destination defined in
.Va netwait_ip
are flowing.
-Link state is examined first, followed by
+Link state is examined first, followed by DAD, then
.Dq Li pinging
an IP address to verify network usability.
If no destination can be reached or timeouts are exceeded,
network services are started anyway with no guarantee that
the network is usable.
-Use of this variable requires both
-.Va netwait_ip
-and
-.Va netwait_if
-to be set.
.It Va netwait_ip
.Pq Vt str
Empty by default.
@@ -4612,6 +4608,21 @@ interface if desired.
Defines the total number of seconds to wait for link to become usable,
polled at a 1-second interval.
The default is 30.
+.It Va netwait_dad
+.Pq Vt str
+Set to
+.Dq Li NO
+by default.
+Set to
+.Dq Li YES
+to enable waiting for DAD to complete.
+.It Va netwait_dad_timeout
+.Pq Vt int
+Unset by default.
+Indicates the maximum number of seconds to wait for DAD to complete.
+If zero or unset, the timeout will be one more than the value of the
+.Va net.inet6.ip6.dad_count
+sysctl variable.
.It Va rctl_enable
.Pq Vt bool
If set to