LinuxLists.cc - [PATCH net-next v3 1/2] ipvs: add READ_ONCE barrier for ipvs->sysctl

2024-04-18 14:58:53

Subject: [PATCH net-next v3 1/2] ipvs: add READ_ONCE barrier for ipvs->sysctl_amemthresh

Cc: Julian Anastasov <[email protected]>
Cc: Simon Horman <[email protected]>
Cc: Pablo Neira Ayuso <[email protected]>
Cc: Jozsef Kadlecsik <[email protected]>
Cc: Florian Westphal <[email protected]>
Suggested-by: Julian Anastasov <[email protected]>
Signed-off-by: Alexander Mikhalitsyn <[email protected]>
---
net/netfilter/ipvs/ip_vs_ctl.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index 143a341bbc0a..32be24f0d4e4 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -94,6 +94,7 @@ static void update_defense_level(struct netns_ipvs *ipvs)
{
struct sysinfo i;
int availmem;
+ int amemthresh;
int nomem;
int to_change = -1;

@@ -105,7 +106,8 @@ static void update_defense_level(struct netns_ipvs *ipvs)
/* si_swapinfo(&i); */
/* availmem = availmem - (i.totalswap - i.freeswap); */

- nomem = (availmem < ipvs->sysctl_amemthresh);
+ amemthresh = max(READ_ONCE(ipvs->sysctl_amemthresh), 0);
+ nomem = (availmem < amemthresh);

local_bh_disable();

@@ -145,9 +147,8 @@ static void update_defense_level(struct netns_ipvs *ipvs)
break;
case 1:
if (nomem) {
- ipvs->drop_rate = ipvs->drop_counter
- = ipvs->sysctl_amemthresh /
- (ipvs->sysctl_amemthresh-availmem);
+ ipvs->drop_counter = amemthresh / (amemthresh - availmem);
+ ipvs->drop_rate = ipvs->drop_counter;
ipvs->sysctl_drop_packet = 2;
} else {
ipvs->drop_rate = 0;
@@ -155,9 +156,8 @@ static void update_defense_level(struct netns_ipvs *ipvs)
break;
case 2:
if (nomem) {
- ipvs->drop_rate = ipvs->drop_counter
- = ipvs->sysctl_amemthresh /
- (ipvs->sysctl_amemthresh-availmem);
+ ipvs->drop_counter = amemthresh / (amemthresh - availmem);
+ ipvs->drop_rate = ipvs->drop_counter;
} else {
ipvs->drop_rate = 0;
ipvs->sysctl_drop_packet = 1;
--
2.34.1

2024-04-18 15:27:08

by Aleksandr Mikhalitsyn

[permalink] [raw]

Subject: [PATCH net-next v3 2/2] ipvs: allow some sysctls in non-init user namespaces

Let's make all IPVS sysctls writtable even when
network namespace is owned by non-initial user namespace.

Let's make a few sysctls to be read-only for non-privileged users:
- sync_qlen_max
- sync_sock_size
- run_estimation
- est_cpulist
- est_nice

I'm trying to be conservative with this to prevent
introducing any security issues in there. Maybe,
we can allow more sysctls to be writable, but let's
do this on-demand and when we see real use-case.

This patch is motivated by user request in the LXC
project [1]. Having this can help with running some
Kubernetes [2] or Docker Swarm [3] workloads inside the system
containers.

Link: https://github.com/lxc/lxc/issues/4278 [1]
Link: https://github.com/kubernetes/kubernetes/blob/b722d017a34b300a2284b890448e5a605f21d01e/pkg/proxy/ipvs/proxier.go#L103 [2]
Link: https://github.com/moby/libnetwork/blob/3797618f9a38372e8107d8c06f6ae199e1133ae8/osl/namespace_linux.go#L682 [3]

Cc: Stéphane Graber <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: Julian Anastasov <[email protected]>
Cc: Simon Horman <[email protected]>
Cc: Pablo Neira Ayuso <[email protected]>
Cc: Jozsef Kadlecsik <[email protected]>
Cc: Florian Westphal <[email protected]>
Signed-off-by: Alexander Mikhalitsyn <[email protected]>
---
net/netfilter/ipvs/ip_vs_ctl.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index 32be24f0d4e4..c3ba71aa2654 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -4270,6 +4270,7 @@ static int __net_init ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs)
struct ctl_table *tbl;
int idx, ret;
size_t ctl_table_size = ARRAY_SIZE(vs_vars);
+ bool unpriv = net->user_ns != &init_user_ns;

atomic_set(&ipvs->dropentry, 0);
spin_lock_init(&ipvs->dropentry_lock);
@@ -4284,12 +4285,6 @@ static int __net_init ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs)
tbl = kmemdup(vs_vars, sizeof(vs_vars), GFP_KERNEL);
if (tbl == NULL)
return -ENOMEM;
-
- /* Don't export sysctls to unprivileged users */
- if (net->user_ns != &init_user_ns) {
- tbl[0].procname = NULL;
- ctl_table_size = 0;
- }
} else
tbl = vs_vars;
/* Initialize sysctl defaults */
@@ -4315,10 +4310,17 @@ static int __net_init ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs)
ipvs->sysctl_sync_ports = 1;
tbl[idx++].data = &ipvs->sysctl_sync_ports;
tbl[idx++].data = &ipvs->sysctl_sync_persist_mode;
+
ipvs->sysctl_sync_qlen_max = nr_free_buffer_pages() / 32;
+ if (unpriv)
+ tbl[idx].mode = 0444;
tbl[idx++].data = &ipvs->sysctl_sync_qlen_max;
+
ipvs->sysctl_sync_sock_size = 0;
+ if (unpriv)
+ tbl[idx].mode = 0444;
tbl[idx++].data = &ipvs->sysctl_sync_sock_size;
+
tbl[idx++].data = &ipvs->sysctl_cache_bypass;
tbl[idx++].data = &ipvs->sysctl_expire_nodest_conn;
tbl[idx++].data = &ipvs->sysctl_sloppy_tcp;
@@ -4341,15 +4343,22 @@ static int __net_init ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs)
tbl[idx++].data = &ipvs->sysctl_conn_reuse_mode;
tbl[idx++].data = &ipvs->sysctl_schedule_icmp;
tbl[idx++].data = &ipvs->sysctl_ignore_tunneled;
+
ipvs->sysctl_run_estimation = 1;
+ if (unpriv)
+ tbl[idx].mode = 0444;
tbl[idx].extra2 = ipvs;
tbl[idx++].data = &ipvs->sysctl_run_estimation;

ipvs->est_cpulist_valid = 0;
+ if (unpriv)
+ tbl[idx].mode = 0444;
tbl[idx].extra2 = ipvs;
tbl[idx++].data = &ipvs->sysctl_est_cpulist;

ipvs->sysctl_est_nice = IPVS_EST_NICE;
+ if (unpriv)
+ tbl[idx].mode = 0444;
tbl[idx].extra2 = ipvs;
tbl[idx++].data = &ipvs->sysctl_est_nice;

--
2.34.1

2024-04-21 11:06:29

by Julian Anastasov

[permalink] [raw]

Subject: Re: [PATCH net-next v3 1/2] ipvs: add READ_ONCE barrier for ipvs->sysctl_amemthresh

Hello,

On Thu, 18 Apr 2024, Alexander Mikhalitsyn wrote:

> Cc: Julian Anastasov <[email protected]>
> Cc: Simon Horman <[email protected]>
> Cc: Pablo Neira Ayuso <[email protected]>
> Cc: Jozsef Kadlecsik <[email protected]>
> Cc: Florian Westphal <[email protected]>
> Suggested-by: Julian Anastasov <[email protected]>
> Signed-off-by: Alexander Mikhalitsyn <[email protected]>

Looks good to me, thanks!

Acked-by: Julian Anastasov <[email protected]>

> ---
> net/netfilter/ipvs/ip_vs_ctl.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
> index 143a341bbc0a..32be24f0d4e4 100644
> --- a/net/netfilter/ipvs/ip_vs_ctl.c
> +++ b/net/netfilter/ipvs/ip_vs_ctl.c
> @@ -94,6 +94,7 @@ static void update_defense_level(struct netns_ipvs *ipvs)
> {
> struct sysinfo i;
> int availmem;
> + int amemthresh;
> int nomem;
> int to_change = -1;
>
> @@ -105,7 +106,8 @@ static void update_defense_level(struct netns_ipvs *ipvs)
> /* si_swapinfo(&i); */
> /* availmem = availmem - (i.totalswap - i.freeswap); */
>
> - nomem = (availmem < ipvs->sysctl_amemthresh);
> + amemthresh = max(READ_ONCE(ipvs->sysctl_amemthresh), 0);
> + nomem = (availmem < amemthresh);
>
> local_bh_disable();
>
> @@ -145,9 +147,8 @@ static void update_defense_level(struct netns_ipvs *ipvs)
> break;
> case 1:
> if (nomem) {
> - ipvs->drop_rate = ipvs->drop_counter
> - = ipvs->sysctl_amemthresh /
> - (ipvs->sysctl_amemthresh-availmem);
> + ipvs->drop_counter = amemthresh / (amemthresh - availmem);
> + ipvs->drop_rate = ipvs->drop_counter;
> ipvs->sysctl_drop_packet = 2;
> } else {
> ipvs->drop_rate = 0;
> @@ -155,9 +156,8 @@ static void update_defense_level(struct netns_ipvs *ipvs)
> break;
> case 2:
> if (nomem) {
> - ipvs->drop_rate = ipvs->drop_counter
> - = ipvs->sysctl_amemthresh /
> - (ipvs->sysctl_amemthresh-availmem);
> + ipvs->drop_counter = amemthresh / (amemthresh - availmem);
> + ipvs->drop_rate = ipvs->drop_counter;
> } else {
> ipvs->drop_rate = 0;
> ipvs->sysctl_drop_packet = 1;
> --
> 2.34.1

Regards

--
Julian Anastasov <[email protected]>

2024-04-21 11:07:11

by Julian Anastasov

[permalink] [raw]

Subject: Re: [PATCH net-next v3 2/2] ipvs: allow some sysctls in non-init user namespaces

Hello,

On Thu, 18 Apr 2024, Alexander Mikhalitsyn wrote:

> Let's make all IPVS sysctls writtable even when
> network namespace is owned by non-initial user namespace.
>
> Let's make a few sysctls to be read-only for non-privileged users:
> - sync_qlen_max
> - sync_sock_size
> - run_estimation
> - est_cpulist
> - est_nice
>
> I'm trying to be conservative with this to prevent
> introducing any security issues in there. Maybe,
> we can allow more sysctls to be writable, but let's
> do this on-demand and when we see real use-case.
>
> This patch is motivated by user request in the LXC
> project [1]. Having this can help with running some
> Kubernetes [2] or Docker Swarm [3] workloads inside the system
> containers.
>
> Link: https://github.com/lxc/lxc/issues/4278 [1]
> Link: https://github.com/kubernetes/kubernetes/blob/b722d017a34b300a2284b890448e5a605f21d01e/pkg/proxy/ipvs/proxier.go#L103 [2]
> Link: https://github.com/moby/libnetwork/blob/3797618f9a38372e8107d8c06f6ae199e1133ae8/osl/namespace_linux.go#L682 [3]
>
> Cc: Stéphane Graber <[email protected]>
> Cc: Christian Brauner <[email protected]>
> Cc: Julian Anastasov <[email protected]>
> Cc: Simon Horman <[email protected]>
> Cc: Pablo Neira Ayuso <[email protected]>
> Cc: Jozsef Kadlecsik <[email protected]>
> Cc: Florian Westphal <[email protected]>
> Signed-off-by: Alexander Mikhalitsyn <[email protected]>

Looks good to me, thanks!

Acked-by: Julian Anastasov <[email protected]>

> ---
> net/netfilter/ipvs/ip_vs_ctl.c | 21 +++++++++++++++------
> 1 file changed, 15 insertions(+), 6 deletions(-)
>
> diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
> index 32be24f0d4e4..c3ba71aa2654 100644
> --- a/net/netfilter/ipvs/ip_vs_ctl.c
> +++ b/net/netfilter/ipvs/ip_vs_ctl.c
> @@ -4270,6 +4270,7 @@ static int __net_init ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs)
> struct ctl_table *tbl;
> int idx, ret;
> size_t ctl_table_size = ARRAY_SIZE(vs_vars);
> + bool unpriv = net->user_ns != &init_user_ns;
>
> atomic_set(&ipvs->dropentry, 0);
> spin_lock_init(&ipvs->dropentry_lock);
> @@ -4284,12 +4285,6 @@ static int __net_init ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs)
> tbl = kmemdup(vs_vars, sizeof(vs_vars), GFP_KERNEL);
> if (tbl == NULL)
> return -ENOMEM;
> -
> - /* Don't export sysctls to unprivileged users */
> - if (net->user_ns != &init_user_ns) {
> - tbl[0].procname = NULL;
> - ctl_table_size = 0;
> - }
> } else
> tbl = vs_vars;
> /* Initialize sysctl defaults */
> @@ -4315,10 +4310,17 @@ static int __net_init ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs)
> ipvs->sysctl_sync_ports = 1;
> tbl[idx++].data = &ipvs->sysctl_sync_ports;
> tbl[idx++].data = &ipvs->sysctl_sync_persist_mode;
> +
> ipvs->sysctl_sync_qlen_max = nr_free_buffer_pages() / 32;
> + if (unpriv)
> + tbl[idx].mode = 0444;
> tbl[idx++].data = &ipvs->sysctl_sync_qlen_max;
> +
> ipvs->sysctl_sync_sock_size = 0;
> + if (unpriv)
> + tbl[idx].mode = 0444;
> tbl[idx++].data = &ipvs->sysctl_sync_sock_size;
> +
> tbl[idx++].data = &ipvs->sysctl_cache_bypass;
> tbl[idx++].data = &ipvs->sysctl_expire_nodest_conn;
> tbl[idx++].data = &ipvs->sysctl_sloppy_tcp;
> @@ -4341,15 +4343,22 @@ static int __net_init ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs)
> tbl[idx++].data = &ipvs->sysctl_conn_reuse_mode;
> tbl[idx++].data = &ipvs->sysctl_schedule_icmp;
> tbl[idx++].data = &ipvs->sysctl_ignore_tunneled;
> +
> ipvs->sysctl_run_estimation = 1;
> + if (unpriv)
> + tbl[idx].mode = 0444;
> tbl[idx].extra2 = ipvs;
> tbl[idx++].data = &ipvs->sysctl_run_estimation;
>
> ipvs->est_cpulist_valid = 0;
> + if (unpriv)
> + tbl[idx].mode = 0444;
> tbl[idx].extra2 = ipvs;
> tbl[idx++].data = &ipvs->sysctl_est_cpulist;
>
> ipvs->sysctl_est_nice = IPVS_EST_NICE;
> + if (unpriv)
> + tbl[idx].mode = 0444;
> tbl[idx].extra2 = ipvs;
> tbl[idx++].data = &ipvs->sysctl_est_nice;
>
> --
> 2.34.1
>
>

Regards

--
Julian Anastasov <[email protected]>

2024-04-22 07:35:30

by Aleksandr Mikhalitsyn

[permalink] [raw]

Subject: Re: [PATCH net-next v3 1/2] ipvs: add READ_ONCE barrier for ipvs->sysctl_amemthresh

On Sun, Apr 21, 2024 at 1:06 PM Julian Anastasov <[email protected]> wrote:
>
>
> Hello,

Dear Julian,

Thanks a lot for the fast review and suggestions!

Kind regards,
Alex

>
> On Thu, 18 Apr 2024, Alexander Mikhalitsyn wrote:
>
> > Cc: Julian Anastasov <[email protected]>
> > Cc: Simon Horman <[email protected]>
> > Cc: Pablo Neira Ayuso <[email protected]>
> > Cc: Jozsef Kadlecsik <[email protected]>
> > Cc: Florian Westphal <[email protected]>
> > Suggested-by: Julian Anastasov <[email protected]>
> > Signed-off-by: Alexander Mikhalitsyn <[email protected]>
>
> Looks good to me, thanks!
>
> Acked-by: Julian Anastasov <[email protected]>
>
> > ---
> > net/netfilter/ipvs/ip_vs_ctl.c | 14 +++++++-------
> > 1 file changed, 7 insertions(+), 7 deletions(-)
> >
> > diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
> > index 143a341bbc0a..32be24f0d4e4 100644
> > --- a/net/netfilter/ipvs/ip_vs_ctl.c
> > +++ b/net/netfilter/ipvs/ip_vs_ctl.c
> > @@ -94,6 +94,7 @@ static void update_defense_level(struct netns_ipvs *ipvs)
> > {
> > struct sysinfo i;
> > int availmem;
> > + int amemthresh;
> > int nomem;
> > int to_change = -1;
> >
> > @@ -105,7 +106,8 @@ static void update_defense_level(struct netns_ipvs *ipvs)
> > /* si_swapinfo(&i); */
> > /* availmem = availmem - (i.totalswap - i.freeswap); */
> >
> > - nomem = (availmem < ipvs->sysctl_amemthresh);
> > + amemthresh = max(READ_ONCE(ipvs->sysctl_amemthresh), 0);
> > + nomem = (availmem < amemthresh);
> >
> > local_bh_disable();
> >
> > @@ -145,9 +147,8 @@ static void update_defense_level(struct netns_ipvs *ipvs)
> > break;
> > case 1:
> > if (nomem) {
> > - ipvs->drop_rate = ipvs->drop_counter
> > - = ipvs->sysctl_amemthresh /
> > - (ipvs->sysctl_amemthresh-availmem);
> > + ipvs->drop_counter = amemthresh / (amemthresh - availmem);
> > + ipvs->drop_rate = ipvs->drop_counter;
> > ipvs->sysctl_drop_packet = 2;
> > } else {
> > ipvs->drop_rate = 0;
> > @@ -155,9 +156,8 @@ static void update_defense_level(struct netns_ipvs *ipvs)
> > break;
> > case 2:
> > if (nomem) {
> > - ipvs->drop_rate = ipvs->drop_counter
> > - = ipvs->sysctl_amemthresh /
> > - (ipvs->sysctl_amemthresh-availmem);
> > + ipvs->drop_counter = amemthresh / (amemthresh - availmem);
> > + ipvs->drop_rate = ipvs->drop_counter;
> > } else {
> > ipvs->drop_rate = 0;
> > ipvs->sysctl_drop_packet = 1;
> > --
> > 2.34.1
>
> Regards
>
> --
> Julian Anastasov <[email protected]>
>

2024-05-03 13:07:02

by Julian Anastasov

[permalink] [raw]

Subject: Re: [PATCH net-next v3 2/2] ipvs: allow some sysctls in non-init user namespaces

2024-05-06 14:18:08

by Aleksandr Mikhalitsyn

[permalink] [raw]

Subject: Re: [PATCH net-next v3 2/2] ipvs: allow some sysctls in non-init user namespaces

On Fri, May 3, 2024 at 3:06 PM Julian Anastasov <[email protected]> wrote:>
>
> Hello,
>
> On Thu, 18 Apr 2024, Alexander Mikhalitsyn wrote:
>
> > Let's make all IPVS sysctls writtable even when
> > network namespace is owned by non-initial user namespace.
> >
> > Let's make a few sysctls to be read-only for non-privileged users:
> > - sync_qlen_max
> > - sync_sock_size
> > - run_estimation
> > - est_cpulist
> > - est_nice
> >
> > I'm trying to be conservative with this to prevent
> > introducing any security issues in there. Maybe,
> > we can allow more sysctls to be writable, but let's
> > do this on-demand and when we see real use-case.
> >
> > This patch is motivated by user request in the LXC
> > project [1]. Having this can help with running some
> > Kubernetes [2] or Docker Swarm [3] workloads inside the system
> > containers.
> >
> > Link: https://github.com/lxc/lxc/issues/4278 [1]
> > Link: https://github.com/kubernetes/kubernetes/blob/b722d017a34b300a2284b890448e5a605f21d01e/pkg/proxy/ipvs/proxier.go#L103 [2]
> > Link: https://github.com/moby/libnetwork/blob/3797618f9a38372e8107d8c06f6ae199e1133ae8/osl/namespace_linux.go#L682 [3]
> >
> > Cc: Stéphane Graber <[email protected]>
> > Cc: Christian Brauner <[email protected]>
> > Cc: Julian Anastasov <[email protected]>
> > Cc: Simon Horman <[email protected]>
> > Cc: Pablo Neira Ayuso <[email protected]>
> > Cc: Jozsef Kadlecsik <[email protected]>
> > Cc: Florian Westphal <[email protected]>
> > Signed-off-by: Alexander Mikhalitsyn <[email protected]>
> > ---
> > net/netfilter/ipvs/ip_vs_ctl.c | 21 +++++++++++++++------
> > 1 file changed, 15 insertions(+), 6 deletions(-)
> >
> > diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
> > index 32be24f0d4e4..c3ba71aa2654 100644
> > --- a/net/netfilter/ipvs/ip_vs_ctl.c
> > +++ b/net/netfilter/ipvs/ip_vs_ctl.c
>
> ...
>
> > @@ -4284,12 +4285,6 @@ static int __net_init ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs)
> > tbl = kmemdup(vs_vars, sizeof(vs_vars), GFP_KERNEL);
> > if (tbl == NULL)
> > return -ENOMEM;
> > -
> > - /* Don't export sysctls to unprivileged users */
> > - if (net->user_ns != &init_user_ns) {
> > - tbl[0].procname = NULL;
> > - ctl_table_size = 0;
> > - }
> > } else
> > tbl = vs_vars;
> > /* Initialize sysctl defaults */
>
> Sorry but you have to send v4 because above if-block was
> changed with net-next commit 635470eb0aa7 from today...

Dear Julian,

sorry about the delay with v4 (just rebased it on top of net-next).

Have just sent it
https://lore.kernel.org/all/[email protected]

Kind regards,
Alex

>
> Regards
>
> --
> Julian Anastasov <[email protected]>