Messages in this thread Patch in this message | | | Date | Thu, 14 Oct 2021 01:20:25 +0200 | From | Dmytro Shytyi <> | Subject | Re: [PATCH net-next V10] net: Variable SLAAC: SLAAC with prefixes of arbitrary length in PIO |
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Hello Jakub, Eric, All,
Jakub, > +retry: > + spin_lock_bh(&lock); > + if (stable_privacy_mode) { > + sha1_init(digest); > + memset(&data, 0, sizeof(data)); > + memset(workspace, 0, sizeof(workspace)); > + memcpy(data.hwaddr, idev->dev->perm_addr, idev->dev->addr_len); > + data.prefix[0] = address->s6_addr32[0]; > + data.prefix[1] = address->s6_addr32[1]; > + data.secret = secret; > + data.dad_count = dad_count; > + > + sha1_transform(digest, data.__data, workspace); > + > + temp.s6_addr32[0] = (__force __be32)digest[0]; > + temp.s6_addr32[1] = (__force __be32)digest[1]; > + temp.s6_addr32[2] = (__force __be32)digest[2]; > + temp.s6_addr32[3] = (__force __be32)digest[3]; > + } else { > + get_random_bytes(temp.s6_addr32, 16); > + } > + > + spin_unlock_bh(&lock);
>Is there a reason this code declares all this state on the stack and >protects it with a lock rather than just allocating the memory with >kmalloc()?
As you proposed earlier, in "PATCH net-next V10" the memory is allocated with kmalloc.
Eric, This patch solves "Race to the bottom" problem in VSLAAC.
Thank you!
Best Regards, Dmytro SHYTYI
---- On Thu, 14 Oct 2021 01:03:00 +0200 Dmytro Shytyi <dmytro@shytyi.net> wrote ----
> Variable SLAAC: > [Disabled by default. Can be activated via sysctl] > ["Race to the bottom" problem is solved] > SLAAC with prefixes of arbitrary length in PIO (randomly > generated hostID or stable privacy + privacy extensions). > The main problem is that SLAAC RA allocates a /64 by the Wireless > carrier 4G, 5G to a mobile hotspot, however segmentation of shorter net- > work prefix (ex. /48) is required so that downstream interfaces can be further > subnetted. > Example: uCPE device (4G + WI-FI enabled) receives /48 via Wireless, and > assigns /56 to VNF-Firewall, /56 to WIFI, /56 to Load-Balancer > and /56 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@shytyi.net> > --- > diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h > index ef4a69865737..076d99874797 100644 > --- a/include/linux/ipv6.h > +++ b/include/linux/ipv6.h > @@ -79,6 +79,7 @@ struct ipv6_devconf { > __u32 ioam6_id; > __u32 ioam6_id_wide; > __u8 ioam6_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 b243a53fa985..25606c267809 100644 > --- a/include/uapi/linux/ipv6.h > +++ b/include/uapi/linux/ipv6.h > @@ -193,6 +193,7 @@ enum { > DEVCONF_IOAM6_ENABLED, > DEVCONF_IOAM6_ID, > DEVCONF_IOAM6_ID_WIDE, > + DEVCONF_VARIABLE_SLAAC, > DEVCONF_MAX > }; > diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c > index c6a90b7bbb70..34a12d7f4fb8 100644 > --- a/net/ipv6/addrconf.c > +++ b/net/ipv6/addrconf.c > @@ -241,6 +241,7 @@ static struct ipv6_devconf ipv6_devconf __read_mostly = { > .ioam6_enabled = 0, > .ioam6_id = IOAM6_DEFAULT_IF_ID, > .ioam6_id_wide = IOAM6_DEFAULT_IF_ID_WIDE, > + .variable_slaac = 0, > }; > > static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = { > @@ -300,6 +301,7 @@ static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = { > .ioam6_enabled = 0, > .ioam6_id = IOAM6_DEFAULT_IF_ID, > .ioam6_id_wide = IOAM6_DEFAULT_IF_ID_WIDE, > + .variable_slaac = 0, > }; > > /* Check if link is ready: is it up and is a valid qdisc available */ > @@ -1349,9 +1351,15 @@ 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 < 64 && > + 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 * > @@ -2579,6 +2587,31 @@ 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 = NULL; > + bool prfxs_equal; > + > + 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(); > + > + return result; > +} > + > int addrconf_prefix_rcv_add_addr(struct net *net, struct net_device *dev, > const struct prefix_info *pinfo, > struct inet6_dev *in6_dev, > @@ -2586,9 +2619,17 @@ int addrconf_prefix_rcv_add_addr(struct net *net, struct net_device *dev, > u32 addr_flags, bool sllao, bool tokenized, > __u32 valid_lft, u32 prefered_lft) > { > - struct inet6_ifaddr *ifp = ipv6_get_ifaddr(net, addr, dev, 1); > + struct inet6_ifaddr *ifp = NULL; > + int plen = pinfo->prefix_len; > int create = 0; > > + if (plen > 0 && plen < 64 && > + in6_dev->cnf.addr_gen_mode != IN6_ADDR_GEN_MODE_STABLE_PRIVACY && > + in6_dev->cnf.variable_slaac) > + ifp = ipv6_cmp_rcvd_prsnt_prfxs(ifp, in6_dev, net, pinfo); > + else > + ifp = ipv6_get_ifaddr(net, addr, dev, 1); > + > if (!ifp && valid_lft) { > int max_addresses = in6_dev->cnf.max_addresses; > struct ifa6_config cfg = { > @@ -2667,6 +2708,94 @@ int addrconf_prefix_rcv_add_addr(struct net *net, struct net_device *dev, > } > EXPORT_SYMBOL_GPL(addrconf_prefix_rcv_add_addr); > > +static bool ipv6_reserved_interfaceid(struct in6_addr address) > +{ > + if ((address.s6_addr32[2] | address.s6_addr32[3]) == 0) > + return true; > + > + if (address.s6_addr32[2] == htonl(0x02005eff) && > + ((address.s6_addr32[3] & htonl(0xfe000000)) == htonl(0xfe000000))) > + return true; > + > + if (address.s6_addr32[2] == htonl(0xfdffffff) && > + ((address.s6_addr32[3] & htonl(0xffffff80)) == htonl(0xffffff80))) > + return true; > + > + return false; > +} > + > +static int ipv6_gen_addr_var_plen(struct in6_addr *address, > + u8 dad_count, > + const struct inet6_dev *idev, > + unsigned int rcvd_prfx_len, > + bool stable_privacy_mode) > +{ > + union data_union { > + char __data[SHA1_BLOCK_SIZE]; > + struct { > + struct in6_addr secret; > + __be32 prefix[2]; > + unsigned char hwaddr[MAX_ADDR_LEN]; > + u8 dad_count; > + } __packed; > + }; > + union data_union *data; > + struct in6_addr *secret; > + struct in6_addr *temp; > + struct net *net; > + int *workspace; > + int *digest; > + > + workspace = kmalloc_array(SHA1_WORKSPACE_WORDS, sizeof(__u32), GFP_KERNEL); > + digest = kmalloc_array(SHA1_DIGEST_WORDS, sizeof(__u32), GFP_KERNEL); > + data = kmalloc(sizeof(*data), GFP_KERNEL); > + secret = kmalloc(sizeof(*secret), GFP_KERNEL); > + temp = kmalloc(sizeof(*temp), GFP_KERNEL); > + net = dev_net(idev->dev); > + > + BUILD_BUG_ON(sizeof(data->__data) != sizeof(*data)); > + > + if (stable_privacy_mode) { > + if (idev->cnf.stable_secret.initialized) > + *secret = idev->cnf.stable_secret.secret; > + else if (net->ipv6.devconf_dflt->stable_secret.initialized) > + *secret = net->ipv6.devconf_dflt->stable_secret.secret; > + else > + return -1; > + } > + > +retry: > + if (stable_privacy_mode) { > + sha1_init(digest); > + memset(data, 0, sizeof(*data)); > + memset(workspace, 0, sizeof(*workspace)); > + memcpy(data->hwaddr, idev->dev->perm_addr, idev->dev->addr_len); > + data->prefix[0] = address->s6_addr32[0]; > + data->prefix[1] = address->s6_addr32[1]; > + data->secret = *secret; > + data->dad_count = dad_count; > + > + sha1_transform(digest, data->__data, workspace); > + > + temp->s6_addr32[0] = (__force __be32)digest[0]; > + temp->s6_addr32[1] = (__force __be32)digest[1]; > + temp->s6_addr32[2] = (__force __be32)digest[2]; > + temp->s6_addr32[3] = (__force __be32)digest[3]; > + } else { > + get_random_bytes(temp->s6_addr32, 16); > + } > + > + if (ipv6_reserved_interfaceid(*temp)) { > + dad_count++; > + if (dad_count > dev_net(idev->dev)->ipv6.sysctl.idgen_retries) > + return -1; > + goto retry; > + } > + ipv6_addr_prefix_copy(temp, address, rcvd_prfx_len); > + *address = *temp; > + return 0; > +} > + > void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len, bool sllao) > { > struct prefix_info *pinfo; > @@ -2791,9 +2920,33 @@ void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len, bool sllao) > dev_addr_generated = true; > } > goto ok; > + } else if (pinfo->prefix_len > 0 && pinfo->prefix_len < 64 && > + in6_dev->cnf.variable_slaac) { > + /* SLAAC with prefixes of arbitrary length (Variable SLAAC). > + * draft-mishra-6man-variable-slaac > + * draft-mishra-v6ops-variable-slaac-problem-stmt > + */ > + memcpy(&addr, &pinfo->prefix, 16); > + if (in6_dev->cnf.addr_gen_mode == IN6_ADDR_GEN_MODE_STABLE_PRIVACY) { > + if (!ipv6_gen_addr_var_plen(&addr, > + 0, > + in6_dev, > + pinfo->prefix_len, > + true)) { > + addr_flags |= IFA_F_STABLE_PRIVACY; > + goto ok; > + } > + } else if (!ipv6_gen_addr_var_plen(&addr, > + 0, > + in6_dev, > + pinfo->prefix_len, > + false)) { > + goto ok; > + } > + } else { > + net_dbg_ratelimited("IPv6: Prefix with unexpected length %d\n", > + pinfo->prefix_len); > } > - net_dbg_ratelimited("IPv6 addrconf: prefix with wrong length %d\n", > - pinfo->prefix_len); > goto put; > > ok: > @@ -5542,6 +5679,7 @@ static inline void ipv6_store_devconf(struct ipv6_devconf *cnf, > array[DEVCONF_IOAM6_ENABLED] = cnf->ioam6_enabled; > array[DEVCONF_IOAM6_ID] = cnf->ioam6_id; > array[DEVCONF_IOAM6_ID_WIDE] = cnf->ioam6_id_wide; > + array[DEVCONF_VARIABLE_SLAAC] = cnf->variable_slaac; > } > > static inline size_t inet6_ifla6_size(void) > @@ -6905,6 +7043,13 @@ static const struct ctl_table addrconf_sysctl[] = { > .proc_handler = proc_dointvec, > > }, > + { > + .procname = "variable_slaac", > + .data = &ipv6_devconf.variable_slaac, > + .maxlen = sizeof(int), > + .mode = 0644, > + .proc_handler = proc_dointvec, > + }, > { > .procname = "seg6_enabled", > .data = &ipv6_devconf.seg6_enabled, > >
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