Commit 78dcdffe authored by Davide Caratti's avatar Davide Caratti Committed by Paolo Abeni

net/sched: act_mirred: better wording on protection against excessive stack growth

with commit e2ca070f ("net: sched: protect against stack overflow in
TC act_mirred"), act_mirred protected itself against excessive stack growth
using per_cpu counter of nested calls to tcf_mirred_act(), and capping it
to MIRRED_RECURSION_LIMIT. However, such protection does not detect
recursion/loops in case the packet is enqueued to the backlog (for example,
when the mirred target device has RPS or skb timestamping enabled). Change
the wording from "recursion" to "nesting" to make it more clear to readers.

CC: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: default avatarDavide Caratti <dcaratti@redhat.com>
Reviewed-by: default avatarMarcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: default avatarJamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent 5cf6c22b
...@@ -29,8 +29,8 @@ ...@@ -29,8 +29,8 @@
static LIST_HEAD(mirred_list); static LIST_HEAD(mirred_list);
static DEFINE_SPINLOCK(mirred_list_lock); static DEFINE_SPINLOCK(mirred_list_lock);
#define MIRRED_RECURSION_LIMIT 4 #define MIRRED_NEST_LIMIT 4
static DEFINE_PER_CPU(unsigned int, mirred_rec_level); static DEFINE_PER_CPU(unsigned int, mirred_nest_level);
static bool tcf_mirred_is_act_redirect(int action) static bool tcf_mirred_is_act_redirect(int action)
{ {
...@@ -226,7 +226,7 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb, ...@@ -226,7 +226,7 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb,
struct sk_buff *skb2 = skb; struct sk_buff *skb2 = skb;
bool m_mac_header_xmit; bool m_mac_header_xmit;
struct net_device *dev; struct net_device *dev;
unsigned int rec_level; unsigned int nest_level;
int retval, err = 0; int retval, err = 0;
bool use_reinsert; bool use_reinsert;
bool want_ingress; bool want_ingress;
...@@ -237,11 +237,11 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb, ...@@ -237,11 +237,11 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb,
int mac_len; int mac_len;
bool at_nh; bool at_nh;
rec_level = __this_cpu_inc_return(mirred_rec_level); nest_level = __this_cpu_inc_return(mirred_nest_level);
if (unlikely(rec_level > MIRRED_RECURSION_LIMIT)) { if (unlikely(nest_level > MIRRED_NEST_LIMIT)) {
net_warn_ratelimited("Packet exceeded mirred recursion limit on dev %s\n", net_warn_ratelimited("Packet exceeded mirred recursion limit on dev %s\n",
netdev_name(skb->dev)); netdev_name(skb->dev));
__this_cpu_dec(mirred_rec_level); __this_cpu_dec(mirred_nest_level);
return TC_ACT_SHOT; return TC_ACT_SHOT;
} }
...@@ -310,7 +310,7 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb, ...@@ -310,7 +310,7 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb,
err = tcf_mirred_forward(want_ingress, skb); err = tcf_mirred_forward(want_ingress, skb);
if (err) if (err)
tcf_action_inc_overlimit_qstats(&m->common); tcf_action_inc_overlimit_qstats(&m->common);
__this_cpu_dec(mirred_rec_level); __this_cpu_dec(mirred_nest_level);
return TC_ACT_CONSUMED; return TC_ACT_CONSUMED;
} }
} }
...@@ -322,7 +322,7 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb, ...@@ -322,7 +322,7 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb,
if (tcf_mirred_is_act_redirect(m_eaction)) if (tcf_mirred_is_act_redirect(m_eaction))
retval = TC_ACT_SHOT; retval = TC_ACT_SHOT;
} }
__this_cpu_dec(mirred_rec_level); __this_cpu_dec(mirred_nest_level);
return retval; return retval;
} }
......
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