| Message ID | 20240625205204.3199050-3-amorenoz@redhat.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | net: openvswitch: Add sample multicasting. | expand |
On Tue, Jun 25, 2024 at 10:51:45PM +0200, Adrian Moreno wrote: > If the action has a user_cookie, pass it along to the sample so it can > be easily identified. > > Signed-off-by: Adrian Moreno <amorenoz@redhat.com> Reviewed-by: Ido Schimmel <idosch@nvidia.com>
On 25 Jun 2024, at 22:51, Adrian Moreno wrote: > If the action has a user_cookie, pass it along to the sample so it can > be easily identified. > > Signed-off-by: Adrian Moreno <amorenoz@redhat.com> > --- > net/sched/act_sample.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/net/sched/act_sample.c b/net/sched/act_sample.c > index a69b53d54039..2ceb4d141b71 100644 > --- a/net/sched/act_sample.c > +++ b/net/sched/act_sample.c > @@ -167,7 +167,9 @@ TC_INDIRECT_SCOPE int tcf_sample_act(struct sk_buff *skb, > { > struct tcf_sample *s = to_sample(a); > struct psample_group *psample_group; > + u8 cookie_data[TC_COOKIE_MAX_SIZE]; > struct psample_metadata md = {}; > + struct tc_cookie *user_cookie; > int retval; > > tcf_lastuse_update(&s->tcf_tm); > @@ -189,6 +191,16 @@ TC_INDIRECT_SCOPE int tcf_sample_act(struct sk_buff *skb, > if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev)) > skb_push(skb, skb->mac_len); > > + rcu_read_lock(); > + user_cookie = rcu_dereference(a->user_cookie); > + if (user_cookie) { > + memcpy(cookie_data, user_cookie->data, > + user_cookie->len); Maybe I’m over paranoid, but can we assume user_cookie->len, will not be larger than TC_COOKIE_MAX_SIZE? Or should we do something like min(user_cookie->len, sizeof(cookie_data)) > + md.user_cookie = cookie_data; > + md.user_cookie_len = user_cookie->len; > + } > + rcu_read_unlock(); > + > md.trunc_size = s->truncate ? s->trunc_size : skb->len; > psample_sample_packet(psample_group, skb, s->rate, &md); > > -- > 2.45.1
On Wed, Jun 26, 2024 at 04:28:01PM GMT, Eelco Chaudron wrote: > > > On 25 Jun 2024, at 22:51, Adrian Moreno wrote: > > > If the action has a user_cookie, pass it along to the sample so it can > > be easily identified. > > > > Signed-off-by: Adrian Moreno <amorenoz@redhat.com> > > --- > > net/sched/act_sample.c | 12 ++++++++++++ > > 1 file changed, 12 insertions(+) > > > > diff --git a/net/sched/act_sample.c b/net/sched/act_sample.c > > index a69b53d54039..2ceb4d141b71 100644 > > --- a/net/sched/act_sample.c > > +++ b/net/sched/act_sample.c > > @@ -167,7 +167,9 @@ TC_INDIRECT_SCOPE int tcf_sample_act(struct sk_buff *skb, > > { > > struct tcf_sample *s = to_sample(a); > > struct psample_group *psample_group; > > + u8 cookie_data[TC_COOKIE_MAX_SIZE]; > > struct psample_metadata md = {}; > > + struct tc_cookie *user_cookie; > > int retval; > > > > tcf_lastuse_update(&s->tcf_tm); > > @@ -189,6 +191,16 @@ TC_INDIRECT_SCOPE int tcf_sample_act(struct sk_buff *skb, > > if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev)) > > skb_push(skb, skb->mac_len); > > > > + rcu_read_lock(); > > + user_cookie = rcu_dereference(a->user_cookie); > > + if (user_cookie) { > > + memcpy(cookie_data, user_cookie->data, > > + user_cookie->len); > > Maybe I’m over paranoid, but can we assume user_cookie->len, will not be larger than TC_COOKIE_MAX_SIZE? > Or should we do something like min(user_cookie->len, sizeof(cookie_data)) > I think it's good to be paranoid with this kind of things. I do, however, think it should be safe to use. The cookie is extracted from the netlink attribute directly and its length is verified with the nla_policy [1]. So nothing that comes into the kernel should be larger than TC_COOKIE_MAX_SIZE. I guess if there is some previous bug that allows for the size to get corrupted, then this might happen but doing those kind of checks in the fast path seems a bit excessive. For example, Ilya argued in v2 [2] that we should avoid zeroing "u8 cookie_data[TC_COOKIE_MAX_SIZE]" to safe the unneeded cycles. [1] https://github.com/torvalds/linux/blob/55027e689933ba2e64f3d245fb1ff185b3e7fc81/net/sched/act_api.c#L1299 [2] https://patchwork.kernel.org/project/netdevbpf/patch/20240603185647.2310748-3-amorenoz@redhat.com/ Thanks. Adrián > > + md.user_cookie = cookie_data; > > + md.user_cookie_len = user_cookie->len; > > + } > > + rcu_read_unlock(); > > + > > md.trunc_size = s->truncate ? s->trunc_size : skb->len; > > psample_sample_packet(psample_group, skb, s->rate, &md); > > > > -- > > 2.45.1 >
On 26 Jun 2024, at 22:06, Adrián Moreno wrote: > On Wed, Jun 26, 2024 at 04:28:01PM GMT, Eelco Chaudron wrote: >> >> >> On 25 Jun 2024, at 22:51, Adrian Moreno wrote: >> >>> If the action has a user_cookie, pass it along to the sample so it can >>> be easily identified. >>> >>> Signed-off-by: Adrian Moreno <amorenoz@redhat.com> >>> --- >>> net/sched/act_sample.c | 12 ++++++++++++ >>> 1 file changed, 12 insertions(+) >>> >>> diff --git a/net/sched/act_sample.c b/net/sched/act_sample.c >>> index a69b53d54039..2ceb4d141b71 100644 >>> --- a/net/sched/act_sample.c >>> +++ b/net/sched/act_sample.c >>> @@ -167,7 +167,9 @@ TC_INDIRECT_SCOPE int tcf_sample_act(struct sk_buff *skb, >>> { >>> struct tcf_sample *s = to_sample(a); >>> struct psample_group *psample_group; >>> + u8 cookie_data[TC_COOKIE_MAX_SIZE]; >>> struct psample_metadata md = {}; >>> + struct tc_cookie *user_cookie; >>> int retval; >>> >>> tcf_lastuse_update(&s->tcf_tm); >>> @@ -189,6 +191,16 @@ TC_INDIRECT_SCOPE int tcf_sample_act(struct sk_buff *skb, >>> if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev)) >>> skb_push(skb, skb->mac_len); >>> >>> + rcu_read_lock(); >>> + user_cookie = rcu_dereference(a->user_cookie); >>> + if (user_cookie) { >>> + memcpy(cookie_data, user_cookie->data, >>> + user_cookie->len); >> >> Maybe I’m over paranoid, but can we assume user_cookie->len, will not be larger than TC_COOKIE_MAX_SIZE? >> Or should we do something like min(user_cookie->len, sizeof(cookie_data)) >> > > I think it's good to be paranoid with this kind of things. I do, > however, think it should be safe to use. The cookie is extracted from > the netlink attribute directly and its length is verified with the > nla_policy [1]. So nothing that comes into the kernel should be larger > than TC_COOKIE_MAX_SIZE. ACK, confirmed that [1] seems to be the only way to set the cookie. So this patch seems fine to me too. Acked-by: Eelco Chaudron <echaudro@redhat.com> > I guess if there is some previous bug that allows for the size to get > corrupted, then this might happen but doing those kind of checks in the > fast path seems a bit excessive. For example, Ilya argued in v2 [2] that > we should avoid zeroing "u8 cookie_data[TC_COOKIE_MAX_SIZE]" to safe the > unneeded cycles. > > [1] https://github.com/torvalds/linux/blob/55027e689933ba2e64f3d245fb1ff185b3e7fc81/net/sched/act_api.c#L1299 > [2] https://patchwork.kernel.org/project/netdevbpf/patch/20240603185647.2310748-3-amorenoz@redhat.com/ > > Thanks. > Adrián > >>> + md.user_cookie = cookie_data; >>> + md.user_cookie_len = user_cookie->len; >>> + } >>> + rcu_read_unlock(); >>> + >>> md.trunc_size = s->truncate ? s->trunc_size : skb->len; >>> psample_sample_packet(psample_group, skb, s->rate, &md); >>> >>> -- >>> 2.45.1 >>
diff --git a/net/sched/act_sample.c b/net/sched/act_sample.c index a69b53d54039..2ceb4d141b71 100644 --- a/net/sched/act_sample.c +++ b/net/sched/act_sample.c @@ -167,7 +167,9 @@ TC_INDIRECT_SCOPE int tcf_sample_act(struct sk_buff *skb, { struct tcf_sample *s = to_sample(a); struct psample_group *psample_group; + u8 cookie_data[TC_COOKIE_MAX_SIZE]; struct psample_metadata md = {}; + struct tc_cookie *user_cookie; int retval; tcf_lastuse_update(&s->tcf_tm); @@ -189,6 +191,16 @@ TC_INDIRECT_SCOPE int tcf_sample_act(struct sk_buff *skb, if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev)) skb_push(skb, skb->mac_len); + rcu_read_lock(); + user_cookie = rcu_dereference(a->user_cookie); + if (user_cookie) { + memcpy(cookie_data, user_cookie->data, + user_cookie->len); + md.user_cookie = cookie_data; + md.user_cookie_len = user_cookie->len; + } + rcu_read_unlock(); + md.trunc_size = s->truncate ? s->trunc_size : skb->len; psample_sample_packet(psample_group, skb, s->rate, &md);
If the action has a user_cookie, pass it along to the sample so it can be easily identified. Signed-off-by: Adrian Moreno <amorenoz@redhat.com> --- net/sched/act_sample.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)