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Message-ID: <1766bdb2894.11cec656f187711.2683040319761227283@shytyi.net>
Date: Wed, 16 Dec 2020 15:01:33 +0100
From: Dmytro Shytyi <dmytro@...tyi.net>
To: "David Miller" <davem@...emloft.net>
Cc: "kuba" <kuba@...nel.org>, "yoshfuji" <yoshfuji@...ux-ipv6.org>,
"kuznet" <kuznet@....inr.ac.ru>,
"liuhangbin" <liuhangbin@...il.com>,
"netdev" <netdev@...r.kernel.org>,
"linux-kernel" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next V8] net: Variable SLAAC: SLAAC with prefixes of
arbitrary length in PIO
Hello David,
Thank you for your comment.
Asnwers in-line.
Take care,
Dmytro SHYTYI
---- On Wed, 16 Dec 2020 01:00:49 +0100 David Miller <davem@...emloft.net> wrote ----
> From: Dmytro Shytyi <dmytro@...tyi.net>
> Date: Wed, 09 Dec 2020 04:27:54 +0100
>
> > Variable SLAAC [Can be activated via sysctl]:
> > SLAAC with prefixes of arbitrary length in PIO (randomly
> > generated hostID or stable privacy + privacy extensions).
> > The main problem is that SLAAC RA or PD allocates a /64 by the Wireless
> > carrier 4G, 5G to a mobile hotspot, however segmentation of the /64 via
> > SLAAC is required so that downstream interfaces can be further subnetted.
> > Example: uCPE device (4G + WI-FI enabled) receives /64 via Wireless, and
> > assigns /72 to VNF-Firewall, /72 to WIFI, /72 to VNF-Router, /72 to
> > Load-Balancer and /72 to wired connected devices.
> > IETF document that defines problem statement:
> > draft-mishra-v6ops-variable-slaac-problem-stmt
> > IETF document that specifies variable slaac:
> > draft-mishra-6man-variable-slaac
> >
> > Signed-off-by: Dmytro Shytyi <dmytro@...tyi.net>
> > ---
> > diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
> > index dda61d150a13..67ca3925463c 100644
> > --- a/include/linux/ipv6.h
> > +++ b/include/linux/ipv6.h
> > @@ -75,6 +75,7 @@ struct ipv6_devconf {
> > __s32 disable_policy;
> > __s32 ndisc_tclass;
> > __s32 rpl_seg_enabled;
> > + __s32 variable_slaac;
> >
> > struct ctl_table_header *sysctl_header;
> > };
> > diff --git a/include/uapi/linux/ipv6.h b/include/uapi/linux/ipv6.h
> > index 13e8751bf24a..f2af4f9fba2d 100644
> > --- a/include/uapi/linux/ipv6.h
> > +++ b/include/uapi/linux/ipv6.h
> > @@ -189,7 +189,8 @@ enum {
> > DEVCONF_ACCEPT_RA_RT_INFO_MIN_PLEN,
> > DEVCONF_NDISC_TCLASS,
> > DEVCONF_RPL_SEG_ENABLED,
> > - DEVCONF_MAX
> > + DEVCONF_MAX,
> > + DEVCONF_VARIABLE_SLAAC
> > };
> >
> >
> > diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
> > index eff2cacd5209..07afe4ce984e 100644
> > --- a/net/ipv6/addrconf.c
> > +++ b/net/ipv6/addrconf.c
> > @@ -236,6 +236,7 @@ static struct ipv6_devconf ipv6_devconf __read_mostly = {
> > .addr_gen_mode = IN6_ADDR_GEN_MODE_EUI64,
> > .disable_policy = 0,
> > .rpl_seg_enabled = 0,
> > + .variable_slaac = 0,
> > };
> >
> > static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
> > @@ -291,6 +292,7 @@ static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
> > .addr_gen_mode = IN6_ADDR_GEN_MODE_EUI64,
> > .disable_policy = 0,
> > .rpl_seg_enabled = 0,
> > + .variable_slaac = 0,
> > };
> >
> > /* Check if link is ready: is it up and is a valid qdisc available */
> > @@ -1340,9 +1342,15 @@ static int ipv6_create_tempaddr(struct inet6_ifaddr *ifp, bool block)
> > goto out;
> > }
> > in6_ifa_hold(ifp);
> > - memcpy(addr.s6_addr, ifp->addr.s6_addr, 8);
> > - ipv6_gen_rnd_iid(&addr);
> >
> > + if (ifp->prefix_len == 64) {
> > + memcpy(addr.s6_addr, ifp->addr.s6_addr, 8);
> > + ipv6_gen_rnd_iid(&addr);
> > + } else if (ifp->prefix_len > 0 && ifp->prefix_len <= 128 &&
> > + idev->cnf.variable_slaac) {
> > + get_random_bytes(addr.s6_addr, 16);
> > + ipv6_addr_prefix_copy(&addr, &ifp->addr, ifp->prefix_len);
> > + }
> > age = (now - ifp->tstamp) / HZ;
> >
> > regen_advance = idev->cnf.regen_max_retry *
> > @@ -2569,6 +2577,37 @@ static bool is_addr_mode_generate_stable(struct inet6_dev *idev)
> > idev->cnf.addr_gen_mode == IN6_ADDR_GEN_MODE_RANDOM;
> > }
> >
> > +static struct inet6_ifaddr *ipv6_cmp_rcvd_prsnt_prfxs(struct inet6_ifaddr *ifp,
> > + struct inet6_dev *in6_dev,
> > + struct net *net,
> > + const struct prefix_info *pinfo)
> > +{
> > + struct inet6_ifaddr *result_base = NULL;
> > + struct inet6_ifaddr *result = NULL;
> > + bool prfxs_equal;
> > +
> > + result_base = result;
>
> This is NULL, are you sure you didn't mewan to init this to 'ifp'
> or similar instead?
[Dmytro] I put the entire function to comment below the instructions.
[Dmytro]:
+static struct inet6_ifaddr *ipv6_cmp_rcvd_prsnt_prfxs(struct inet6_ifaddr *ifp,
+ struct inet6_dev *in6_dev,
+ struct net *net,
+ const struct prefix_info *pinfo)
+{
+ struct inet6_ifaddr *result_base = NULL;
+ struct inet6_ifaddr *result = NULL;
+ bool prfxs_equal;
+
+ result_base = result;
+ rcu_read_lock();
+ list_for_each_entry_rcu(ifp, &in6_dev->addr_list, if_list) {
+ if (!net_eq(dev_net(ifp->idev->dev), net))
+ continue;
+ prfxs_equal =
+ ipv6_prefix_equal(&pinfo->prefix, &ifp->addr, pinfo->prefix_len);
+ if (prfxs_equal && pinfo->prefix_len == ifp->prefix_len) {
+ result = ifp;
+ in6_ifa_hold(ifp);
+ break;
+ }
+ }
+ rcu_read_unlock();
+ if (result_base != result)
+ ifp = result;
+ else
+ ifp = NULL;
+
+ return ifp;
+}
+
[Dmytro]:
1st initial stage is :
+ result_base = result;
2nd stage is (as you mention, 'result' will be assigned to 'ifp', in the process):
+ result = ifp;
3rd stage is to compare if "result_base" and "result" are not equal (and take required action).
if (result_base != result)
+ ifp = result;
+ else
+ ifp = NULL;
Looks more/less ok for me.
Thanks.
> Thanks.
>
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