Re: [PATCH v2 11/14] networking: Update to register_net_sysctl_sz

Przemek Kitszel
2023-08-08T18:57:40Z

On 7/31/23 09:17, Joel Granados wrote:
> Move from register_net_sysctl to register_net_sysctl_sz for all the
> networking related files. Do this while making sure to mirror the NULL
> assignments with a table_size of zero for the unprivileged users.
>
> We need to move to the new function in preparation for when we change
> SIZE_MAX to ARRAY_SIZE() in the register_net_sysctl macro. Failing to do
> so would erroneously allow ARRAY_SIZE() to be called on a pointer. We
> hold off the SIZE_MAX to ARRAY_SIZE change until we have migrated all
> the relevant net sysctl registering functions to register_net_sysctl_sz
> in subsequent commits.
>
> An additional size function was added to the following files in order to
> calculate the size of an array that is defined in another file:
> include/net/ipv6.h
> net/ipv6/icmp.c
> net/ipv6/route.c
> net/ipv6/sysctl_net_ipv6.c
>
> Signed-off-by: Joel Granados <j.granados@samsung.com>
> ---
> include/net/ipv6.h | 2 ++
> net/core/neighbour.c | 8 ++++++--
> net/core/sysctl_net_core.c | 3 ++-
> net/ieee802154/6lowpan/reassembly.c | 8 ++++++--
> net/ipv4/devinet.c | 3 ++-
> net/ipv4/ip_fragment.c | 3 ++-
> net/ipv4/route.c | 8 ++++++--
> net/ipv4/sysctl_net_ipv4.c | 3 ++-
> net/ipv4/xfrm4_policy.c | 3 ++-
> net/ipv6/addrconf.c | 3 ++-
> net/ipv6/icmp.c | 5 +++++
> net/ipv6/reassembly.c | 3 ++-
> net/ipv6/route.c | 13 +++++++++----
> net/ipv6/sysctl_net_ipv6.c | 16 +++++++++++-----
> net/ipv6/xfrm6_policy.c | 3 ++-
> net/mpls/af_mpls.c | 6 ++++--
> net/mptcp/ctrl.c | 3 ++-
> net/rds/tcp.c | 3 ++-
> net/sctp/sysctl.c | 4 +++-
> net/smc/smc_sysctl.c | 3 ++-
> net/unix/sysctl_net_unix.c | 3 ++-
> net/xfrm/xfrm_sysctl.c | 8 ++++++--
> 22 files changed, 82 insertions(+), 32 deletions(-)
>
> diff --git a/include/net/ipv6.h b/include/net/ipv6.h
> index 7332296eca44..63ba68536a20 100644
> --- a/include/net/ipv6.h
> +++ b/include/net/ipv6.h
> @@ -1274,7 +1274,9 @@ static inline int snmp6_unregister_dev(struct inet6_dev *idev) { return 0; }
>
> #ifdef CONFIG_SYSCTL
> struct ctl_table *ipv6_icmp_sysctl_init(struct net *net);
> +size_t ipv6_icmp_sysctl_table_size(void);
> struct ctl_table *ipv6_route_sysctl_init(struct net *net);
> +size_t ipv6_route_sysctl_table_size(struct net *net);
> int ipv6_sysctl_register(void);
> void ipv6_sysctl_unregister(void);
> #endif
> diff --git a/net/core/neighbour.c b/net/core/neighbour.c
> index ddd0f32de20e..adc7fc4ff9bf 100644
> --- a/net/core/neighbour.c
> +++ b/net/core/neighbour.c
> @@ -3779,6 +3779,7 @@ int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
> const char *dev_name_source;
> char neigh_path[ sizeof("net//neigh/") + IFNAMSIZ + IFNAMSIZ ];
> char *p_name;
> + size_t neigh_vars_size;
>
> t = kmemdup(&neigh_sysctl_template, sizeof(*t), GFP_KERNEL_ACCOUNT);
> if (!t)
> @@ -3790,11 +3791,13 @@ int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
> t->neigh_vars[i].extra2 = p;
> }
>
> + neigh_vars_size = ARRAY_SIZE(t->neigh_vars);
> if (dev) {
> dev_name_source = dev->name;
> /* Terminate the table early */
> memset(&t->neigh_vars[NEIGH_VAR_GC_INTERVAL], 0,
> sizeof(t->neigh_vars[NEIGH_VAR_GC_INTERVAL]));
> + neigh_vars_size = NEIGH_VAR_BASE_REACHABLE_TIME_MS;

%NEIGH_VAR_BASE_REACHABLE_TIME_MS is last usable index here, and since
those are 0 based, size is one more, %NEIGH_VAR_GC_INTERVAL.
(spelling it "NEIGH_VAR_BASE_REACHABLE_TIME_MS+1" would be perhaps better?)

> } else {
> struct neigh_table *tbl = p->tbl;
> dev_name_source = "default";
> @@ -3841,8 +3844,9 @@ int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
>
> snprintf(neigh_path, sizeof(neigh_path), "net/%s/neigh/%s",
> p_name, dev_name_source);
> - t->sysctl_header =
> - register_net_sysctl(neigh_parms_net(p), neigh_path, t->neigh_vars);
> + t->sysctl_header = register_net_sysctl_sz(neigh_parms_net(p),
> + neigh_path, t->neigh_vars,
> + neigh_vars_size);
> if (!t->sysctl_header)
> goto free;
>
> diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
> index 782273bb93c2..03f1edb948d7 100644
> --- a/net/core/sysctl_net_core.c
> +++ b/net/core/sysctl_net_core.c
> @@ -712,7 +712,8 @@ static __net_init int sysctl_core_net_init(struct net *net)
> tmp->data += (char *)net - (char *)&init_net;
> }
>
> - net->core.sysctl_hdr = register_net_sysctl(net, "net/core", tbl);
> + net->core.sysctl_hdr = register_net_sysctl_sz(net, "net/core", tbl,
> + ARRAY_SIZE(netns_core_table));
> if (net->core.sysctl_hdr == NULL)
> goto err_reg;
>
> diff --git a/net/ieee802154/6lowpan/reassembly.c b/net/ieee802154/6lowpan/reassembly.c
> index a91283d1e5bf..6dd960ec558c 100644
> --- a/net/ieee802154/6lowpan/reassembly.c
> +++ b/net/ieee802154/6lowpan/reassembly.c
> @@ -360,6 +360,7 @@ static int __net_init lowpan_frags_ns_sysctl_register(struct net *net)
> struct ctl_table_header *hdr;
> struct netns_ieee802154_lowpan *ieee802154_lowpan =
> net_ieee802154_lowpan(net);
> + size_t table_size = ARRAY_SIZE(lowpan_frags_ns_ctl_table);
>
> table = lowpan_frags_ns_ctl_table;
> if (!net_eq(net, &init_net)) {
> @@ -369,8 +370,10 @@ static int __net_init lowpan_frags_ns_sysctl_register(struct net *net)
> goto err_alloc;
>
> /* Don't export sysctls to unprivileged users */
> - if (net->user_ns != &init_user_ns)
> + if (net->user_ns != &init_user_ns) {
> table[0].procname = NULL;
> + table_size = 0;
> + }
> }
>
> table[0].data = &ieee802154_lowpan->fqdir->high_thresh;
> @@ -379,7 +382,8 @@ static int __net_init lowpan_frags_ns_sysctl_register(struct net *net)
> table[1].extra2 = &ieee802154_lowpan->fqdir->high_thresh;
> table[2].data = &ieee802154_lowpan->fqdir->timeout;
>
> - hdr = register_net_sysctl(net, "net/ieee802154/6lowpan", table);
> + hdr = register_net_sysctl_sz(net, "net/ieee802154/6lowpan", table,
> + table_size);
> if (hdr == NULL)
> goto err_reg;
>
> diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
> index 5deac0517ef7..89087844ea6e 100644
> --- a/net/ipv4/devinet.c
> +++ b/net/ipv4/devinet.c
> @@ -2720,7 +2720,8 @@ static __net_init int devinet_init_net(struct net *net)
> goto err_reg_dflt;
>
> err = -ENOMEM;
> - forw_hdr = register_net_sysctl(net, "net/ipv4", tbl);
> + forw_hdr = register_net_sysctl_sz(net, "net/ipv4", tbl,
> + ARRAY_SIZE(ctl_forward_entry));
> if (!forw_hdr)
> goto err_reg_ctl;
> net->ipv4.forw_hdr = forw_hdr;
> diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
> index 69c00ffdcf3e..a4941f53b523 100644
> --- a/net/ipv4/ip_fragment.c
> +++ b/net/ipv4/ip_fragment.c
> @@ -615,7 +615,8 @@ static int __net_init ip4_frags_ns_ctl_register(struct net *net)
> table[2].data = &net->ipv4.fqdir->timeout;
> table[3].data = &net->ipv4.fqdir->max_dist;
>
> - hdr = register_net_sysctl(net, "net/ipv4", table);
> + hdr = register_net_sysctl_sz(net, "net/ipv4", table,
> + ARRAY_SIZE(ip4_frags_ns_ctl_table));
> if (!hdr)
> goto err_reg;
>
> diff --git a/net/ipv4/route.c b/net/ipv4/route.c
> index 98d7e6ba7493..e7e9fba0357a 100644
> --- a/net/ipv4/route.c
> +++ b/net/ipv4/route.c
> @@ -3592,6 +3592,7 @@ static struct ctl_table ipv4_route_netns_table[] = {
> static __net_init int sysctl_route_net_init(struct net *net)
> {
> struct ctl_table *tbl;
> + size_t table_size = ARRAY_SIZE(ipv4_route_netns_table);
>
> tbl = ipv4_route_netns_table;
> if (!net_eq(net, &init_net)) {
> @@ -3603,8 +3604,10 @@ static __net_init int sysctl_route_net_init(struct net *net)
>
> /* Don't export non-whitelisted sysctls to unprivileged users */
> if (net->user_ns != &init_user_ns) {
> - if (tbl[0].procname != ipv4_route_flush_procname)
> + if (tbl[0].procname != ipv4_route_flush_procname) {
> tbl[0].procname = NULL;
> + table_size = 0;
> + }
> }
>
> /* Update the variables to point into the current struct net
> @@ -3615,7 +3618,8 @@ static __net_init int sysctl_route_net_init(struct net *net)
> }
> tbl[0].extra1 = net;
>
> - net->ipv4.route_hdr = register_net_sysctl(net, "net/ipv4/route", tbl);
> + net->ipv4.route_hdr = register_net_sysctl_sz(net, "net/ipv4/route",
> + tbl, table_size);
> if (!net->ipv4.route_hdr)
> goto err_reg;
> return 0;
> diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
> index 2afb0870648b..6ac890b4073f 100644
> --- a/net/ipv4/sysctl_net_ipv4.c
> +++ b/net/ipv4/sysctl_net_ipv4.c
> @@ -1519,7 +1519,8 @@ static __net_init int ipv4_sysctl_init_net(struct net *net)
> }
> }
>
> - net->ipv4.ipv4_hdr = register_net_sysctl(net, "net/ipv4", table);
> + net->ipv4.ipv4_hdr = register_net_sysctl_sz(net, "net/ipv4", table,
> + ARRAY_SIZE(ipv4_net_table));
> if (!net->ipv4.ipv4_hdr)
> goto err_reg;
>
> diff --git a/net/ipv4/xfrm4_policy.c b/net/ipv4/xfrm4_policy.c
> index 9403bbaf1b61..57ea394ffa8c 100644
> --- a/net/ipv4/xfrm4_policy.c
> +++ b/net/ipv4/xfrm4_policy.c
> @@ -178,7 +178,8 @@ static __net_init int xfrm4_net_sysctl_init(struct net *net)
> table[0].data = &net->xfrm.xfrm4_dst_ops.gc_thresh;
> }
>
> - hdr = register_net_sysctl(net, "net/ipv4", table);
> + hdr = register_net_sysctl_sz(net, "net/ipv4", table,
> + ARRAY_SIZE(xfrm4_policy_table));
> if (!hdr)
> goto err_reg;
>
> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
> index e5213e598a04..d615a84965c2 100644
> --- a/net/ipv6/addrconf.c
> +++ b/net/ipv6/addrconf.c
> @@ -7085,7 +7085,8 @@ static int __addrconf_sysctl_register(struct net *net, char *dev_name,
>
> snprintf(path, sizeof(path), "net/ipv6/conf/%s", dev_name);
>
> - p->sysctl_header = register_net_sysctl(net, path, table);
> + p->sysctl_header = register_net_sysctl_sz(net, path, table,
> + ARRAY_SIZE(addrconf_sysctl));
> if (!p->sysctl_header)
> goto free;
>
> diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
> index 65fa5014bc85..a76b01b41b57 100644
> --- a/net/ipv6/icmp.c
> +++ b/net/ipv6/icmp.c
> @@ -1229,4 +1229,9 @@ struct ctl_table * __net_init ipv6_icmp_sysctl_init(struct net *net)
> }
> return table;
> }
> +
> +size_t ipv6_icmp_sysctl_table_size(void)
> +{
> + return ARRAY_SIZE(ipv6_icmp_table_template);
> +}
> #endif
> diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
> index 5bc8a28e67f9..5ebc47da1000 100644
> --- a/net/ipv6/reassembly.c
> +++ b/net/ipv6/reassembly.c
> @@ -470,7 +470,8 @@ static int __net_init ip6_frags_ns_sysctl_register(struct net *net)
> table[1].extra2 = &net->ipv6.fqdir->high_thresh;
> table[2].data = &net->ipv6.fqdir->timeout;
>
> - hdr = register_net_sysctl(net, "net/ipv6", table);
> + hdr = register_net_sysctl_sz(net, "net/ipv6", table,
> + ARRAY_SIZE(ip6_frags_ns_ctl_table));
> if (!hdr)
> goto err_reg;
>
> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> index 64e873f5895f..51c6cdae8723 100644
> --- a/net/ipv6/route.c
> +++ b/net/ipv6/route.c
> @@ -6447,14 +6447,19 @@ struct ctl_table * __net_init ipv6_route_sysctl_init(struct net *net)
> table[8].data = &net->ipv6.sysctl.ip6_rt_min_advmss;
> table[9].data = &net->ipv6.sysctl.ip6_rt_gc_min_interval;
> table[10].data = &net->ipv6.sysctl.skip_notify_on_dev_down;
> -
> - /* Don't export sysctls to unprivileged users */
> - if (net->user_ns != &init_user_ns)
> - table[1].procname = NULL;
> }
>
> return table;
> }
> +
> +size_t ipv6_route_sysctl_table_size(struct net *net)
> +{
> + /* Don't export sysctls to unprivileged users */
> + if (net->user_ns != &init_user_ns)
> + return 0;
> +
> + return ARRAY_SIZE(ipv6_route_table_template);
> +}
> #endif
>
> static int __net_init ip6_route_net_init(struct net *net)
> diff --git a/net/ipv6/sysctl_net_ipv6.c b/net/ipv6/sysctl_net_ipv6.c
> index 94a0a294c6a1..888676163e90 100644
> --- a/net/ipv6/sysctl_net_ipv6.c
> +++ b/net/ipv6/sysctl_net_ipv6.c
> @@ -275,17 +275,23 @@ static int __net_init ipv6_sysctl_net_init(struct net *net)
> if (!ipv6_icmp_table)
> goto out_ipv6_route_table;
>
> - net->ipv6.sysctl.hdr = register_net_sysctl(net, "net/ipv6", ipv6_table);
> + net->ipv6.sysctl.hdr = register_net_sysctl_sz(net, "net/ipv6",
> + ipv6_table,
> + ARRAY_SIZE(ipv6_table_template));
> if (!net->ipv6.sysctl.hdr)
> goto out_ipv6_icmp_table;
>
> - net->ipv6.sysctl.route_hdr =
> - register_net_sysctl(net, "net/ipv6/route", ipv6_route_table);
> + net->ipv6.sysctl.route_hdr = register_net_sysctl_sz(net,
> + "net/ipv6/route",
> + ipv6_route_table,
> + ipv6_route_sysctl_table_size(net));
> if (!net->ipv6.sysctl.route_hdr)
> goto out_unregister_ipv6_table;
>
> - net->ipv6.sysctl.icmp_hdr =
> - register_net_sysctl(net, "net/ipv6/icmp", ipv6_icmp_table);
> + net->ipv6.sysctl.icmp_hdr = register_net_sysctl_sz(net,
> + "net/ipv6/icmp",
> + ipv6_icmp_table,
> + ipv6_icmp_sysctl_table_size());
> if (!net->ipv6.sysctl.icmp_hdr)
> goto out_unregister_route_table;
>
> diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
> index eecc5e59da17..8f931e46b460 100644
> --- a/net/ipv6/xfrm6_policy.c
> +++ b/net/ipv6/xfrm6_policy.c
> @@ -205,7 +205,8 @@ static int __net_init xfrm6_net_sysctl_init(struct net *net)
> table[0].data = &net->xfrm.xfrm6_dst_ops.gc_thresh;
> }
>
> - hdr = register_net_sysctl(net, "net/ipv6", table);
> + hdr = register_net_sysctl_sz(net, "net/ipv6", table,
> + ARRAY_SIZE(xfrm6_policy_table));
> if (!hdr)
> goto err_reg;
>
> diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
> index bf6e81d56263..1af29af65388 100644
> --- a/net/mpls/af_mpls.c
> +++ b/net/mpls/af_mpls.c
> @@ -1419,7 +1419,8 @@ static int mpls_dev_sysctl_register(struct net_device *dev,
>
> snprintf(path, sizeof(path), "net/mpls/conf/%s", dev->name);
>
> - mdev->sysctl = register_net_sysctl(net, path, table);
> + mdev->sysctl = register_net_sysctl_sz(net, path, table,
> + ARRAY_SIZE(mpls_dev_table));
> if (!mdev->sysctl)
> goto free;
>
> @@ -2689,7 +2690,8 @@ static int mpls_net_init(struct net *net)
> for (i = 0; i < ARRAY_SIZE(mpls_table) - 1; i++)
> table[i].data = (char *)net + (uintptr_t)table[i].data;
>
> - net->mpls.ctl = register_net_sysctl(net, "net/mpls", table);
> + net->mpls.ctl = register_net_sysctl_sz(net, "net/mpls", table,
> + ARRAY_SIZE(mpls_table));
> if (net->mpls.ctl == NULL) {
> kfree(table);
> return -ENOMEM;
> diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c
> index ae20b7d92e28..43e540328a52 100644
> --- a/net/mptcp/ctrl.c
> +++ b/net/mptcp/ctrl.c
> @@ -150,7 +150,8 @@ static int mptcp_pernet_new_table(struct net *net, struct mptcp_pernet *pernet)
> table[4].data = &pernet->stale_loss_cnt;
> table[5].data = &pernet->pm_type;
>
> - hdr = register_net_sysctl(net, MPTCP_SYSCTL_PATH, table);
> + hdr = register_net_sysctl_sz(net, MPTCP_SYSCTL_PATH, table,
> + ARRAY_SIZE(mptcp_sysctl_table));
> if (!hdr)
> goto err_reg;
>
> diff --git a/net/rds/tcp.c b/net/rds/tcp.c
> index c5b86066ff66..2dba7505b414 100644
> --- a/net/rds/tcp.c
> +++ b/net/rds/tcp.c
> @@ -565,7 +565,8 @@ static __net_init int rds_tcp_init_net(struct net *net)
> }
> tbl[RDS_TCP_SNDBUF].data = &rtn->sndbuf_size;
> tbl[RDS_TCP_RCVBUF].data = &rtn->rcvbuf_size;
> - rtn->rds_tcp_sysctl = register_net_sysctl(net, "net/rds/tcp", tbl);
> + rtn->rds_tcp_sysctl = register_net_sysctl_sz(net, "net/rds/tcp", tbl,
> + ARRAY_SIZE(rds_tcp_sysctl_table));
> if (!rtn->rds_tcp_sysctl) {
> pr_warn("could not register sysctl\n");
> err = -ENOMEM;
> diff --git a/net/sctp/sysctl.c b/net/sctp/sysctl.c
> index a7a9136198fd..f65d6f92afcb 100644
> --- a/net/sctp/sysctl.c
> +++ b/net/sctp/sysctl.c
> @@ -612,7 +612,9 @@ int sctp_sysctl_net_register(struct net *net)
> table[SCTP_PF_RETRANS_IDX].extra2 = &net->sctp.ps_retrans;
> table[SCTP_PS_RETRANS_IDX].extra1 = &net->sctp.pf_retrans;
>
> - net->sctp.sysctl_header = register_net_sysctl(net, "net/sctp", table);
> + net->sctp.sysctl_header = register_net_sysctl_sz(net, "net/sctp",
> + table,
> + ARRAY_SIZE(sctp_net_table));
> if (net->sctp.sysctl_header == NULL) {
> kfree(table);
> return -ENOMEM;
> diff --git a/net/smc/smc_sysctl.c b/net/smc/smc_sysctl.c
> index b6f79fabb9d3..3ab2d8eefc55 100644
> --- a/net/smc/smc_sysctl.c
> +++ b/net/smc/smc_sysctl.c
> @@ -81,7 +81,8 @@ int __net_init smc_sysctl_net_init(struct net *net)
> table[i].data += (void *)net - (void *)&init_net;
> }
>
> - net->smc.smc_hdr = register_net_sysctl(net, "net/smc", table);
> + net->smc.smc_hdr = register_net_sysctl_sz(net, "net/smc", table,
> + ARRAY_SIZE(smc_table));
> if (!net->smc.smc_hdr)
> goto err_reg;
>
> diff --git a/net/unix/sysctl_net_unix.c b/net/unix/sysctl_net_unix.c
> index 500129aa710c..3e84b31c355a 100644
> --- a/net/unix/sysctl_net_unix.c
> +++ b/net/unix/sysctl_net_unix.c
> @@ -36,7 +36,8 @@ int __net_init unix_sysctl_register(struct net *net)
> table[0].data = &net->unx.sysctl_max_dgram_qlen;
> }
>
> - net->unx.ctl = register_net_sysctl(net, "net/unix", table);
> + net->unx.ctl = register_net_sysctl_sz(net, "net/unix", table,
> + ARRAY_SIZE(unix_table));
> if (net->unx.ctl == NULL)
> goto err_reg;
>
> diff --git a/net/xfrm/xfrm_sysctl.c b/net/xfrm/xfrm_sysctl.c
> index 0c6c5ef65f9d..7fdeafc838a7 100644
> --- a/net/xfrm/xfrm_sysctl.c
> +++ b/net/xfrm/xfrm_sysctl.c
> @@ -44,6 +44,7 @@ static struct ctl_table xfrm_table[] = {
> int __net_init xfrm_sysctl_init(struct net *net)
> {
> struct ctl_table *table;
> + size_t table_size = ARRAY_SIZE(xfrm_table);
>
> __xfrm_sysctl_init(net);
>
> @@ -56,10 +57,13 @@ int __net_init xfrm_sysctl_init(struct net *net)
> table[3].data = &net->xfrm.sysctl_acq_expires;
>
> /* Don't export sysctls to unprivileged users */
> - if (net->user_ns != &init_user_ns)
> + if (net->user_ns != &init_user_ns) {
> table[0].procname = NULL;

do we still have to set procname to NULL, even if passed size is 0?
(same thing for all earlier occurences)

> + table_size = 0;
> + }
>
> - net->xfrm.sysctl_hdr = register_net_sysctl(net, "net/core", table);
> + net->xfrm.sysctl_hdr = register_net_sysctl_sz(net, "net/core", table,
> + table_size);
> if (!net->xfrm.sysctl_hdr)
> goto out_register;
> return 0;

overall this patch looks sane, and whole series looks very promissing,
thanks