28e6b67f0b
Since commit55334a5db5("net_sched: act: refuse to remove bound action outside"), we end up with a wrong reference count for a tc action. Test case 1: FOO="1,6 0 0 4294967295," BAR="1,6 0 0 4294967294," tc filter add dev foo parent 1: bpf bytecode "$FOO" flowid 1:1 \ action bpf bytecode "$FOO" tc actions show action bpf action order 0: bpf bytecode '1,6 0 0 4294967295' default-action pipe index 1 ref 1 bind 1 tc actions replace action bpf bytecode "$BAR" index 1 tc actions show action bpf action order 0: bpf bytecode '1,6 0 0 4294967294' default-action pipe index 1 ref 2 bind 1 tc actions replace action bpf bytecode "$FOO" index 1 tc actions show action bpf action order 0: bpf bytecode '1,6 0 0 4294967295' default-action pipe index 1 ref 3 bind 1 Test case 2: FOO="1,6 0 0 4294967295," tc filter add dev foo parent 1: bpf bytecode "$FOO" flowid 1:1 action ok tc actions show action gact action order 0: gact action pass random type none pass val 0 index 1 ref 1 bind 1 tc actions add action drop index 1 RTNETLINK answers: File exists [...] tc actions show action gact action order 0: gact action pass random type none pass val 0 index 1 ref 2 bind 1 tc actions add action drop index 1 RTNETLINK answers: File exists [...] tc actions show action gact action order 0: gact action pass random type none pass val 0 index 1 ref 3 bind 1 What happens is that in tcf_hash_check(), we check tcf_common for a given index and increase tcfc_refcnt and conditionally tcfc_bindcnt when we've found an existing action. Now there are the following cases: 1) We do a late binding of an action. In that case, we leave the tcfc_refcnt/tcfc_bindcnt increased and are done with the ->init() handler. This is correctly handeled. 2) We replace the given action, or we try to add one without replacing and find out that the action at a specific index already exists (thus, we go out with error in that case). In case of 2), we have to undo the reference count increase from tcf_hash_check() in the tcf_hash_check() function. Currently, we fail to do so because of the 'tcfc_bindcnt > 0' check which bails out early with an -EPERM error. Now, while commit55334a5db5prevents 'tc actions del action ...' on an already classifier-bound action to drop the reference count (which could then become negative, wrap around etc), this restriction only accounts for invocations outside a specific action's ->init() handler. One possible solution would be to add a flag thus we possibly trigger the -EPERM ony in situations where it is indeed relevant. After the patch, above test cases have correct reference count again. Fixes:55334a5db5("net_sched: act: refuse to remove bound action outside") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Cong Wang <cwang@twopensource.com> Signed-off-by: David S. Miller <davem@davemloft.net>
133 lines
3.9 KiB
C
133 lines
3.9 KiB
C
#ifndef __NET_ACT_API_H
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#define __NET_ACT_API_H
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/*
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* Public police action API for classifiers/qdiscs
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*/
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#include <net/sch_generic.h>
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#include <net/pkt_sched.h>
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struct tcf_common {
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struct hlist_node tcfc_head;
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u32 tcfc_index;
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int tcfc_refcnt;
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int tcfc_bindcnt;
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u32 tcfc_capab;
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int tcfc_action;
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struct tcf_t tcfc_tm;
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struct gnet_stats_basic_packed tcfc_bstats;
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struct gnet_stats_queue tcfc_qstats;
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struct gnet_stats_rate_est64 tcfc_rate_est;
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spinlock_t tcfc_lock;
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struct rcu_head tcfc_rcu;
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};
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#define tcf_head common.tcfc_head
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#define tcf_index common.tcfc_index
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#define tcf_refcnt common.tcfc_refcnt
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#define tcf_bindcnt common.tcfc_bindcnt
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#define tcf_capab common.tcfc_capab
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#define tcf_action common.tcfc_action
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#define tcf_tm common.tcfc_tm
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#define tcf_bstats common.tcfc_bstats
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#define tcf_qstats common.tcfc_qstats
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#define tcf_rate_est common.tcfc_rate_est
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#define tcf_lock common.tcfc_lock
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#define tcf_rcu common.tcfc_rcu
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struct tcf_hashinfo {
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struct hlist_head *htab;
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unsigned int hmask;
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spinlock_t lock;
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u32 index;
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};
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static inline unsigned int tcf_hash(u32 index, unsigned int hmask)
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{
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return index & hmask;
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}
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static inline int tcf_hashinfo_init(struct tcf_hashinfo *hf, unsigned int mask)
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{
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int i;
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spin_lock_init(&hf->lock);
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hf->index = 0;
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hf->hmask = mask;
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hf->htab = kzalloc((mask + 1) * sizeof(struct hlist_head),
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GFP_KERNEL);
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if (!hf->htab)
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return -ENOMEM;
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for (i = 0; i < mask + 1; i++)
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INIT_HLIST_HEAD(&hf->htab[i]);
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return 0;
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}
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static inline void tcf_hashinfo_destroy(struct tcf_hashinfo *hf)
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{
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kfree(hf->htab);
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}
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#ifdef CONFIG_NET_CLS_ACT
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#define ACT_P_CREATED 1
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#define ACT_P_DELETED 1
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struct tc_action {
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void *priv;
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const struct tc_action_ops *ops;
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__u32 type; /* for backward compat(TCA_OLD_COMPAT) */
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__u32 order;
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struct list_head list;
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};
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struct tc_action_ops {
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struct list_head head;
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struct tcf_hashinfo *hinfo;
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char kind[IFNAMSIZ];
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__u32 type; /* TBD to match kind */
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struct module *owner;
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int (*act)(struct sk_buff *, const struct tc_action *, struct tcf_result *);
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int (*dump)(struct sk_buff *, struct tc_action *, int, int);
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void (*cleanup)(struct tc_action *, int bind);
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int (*lookup)(struct tc_action *, u32);
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int (*init)(struct net *net, struct nlattr *nla,
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struct nlattr *est, struct tc_action *act, int ovr,
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int bind);
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int (*walk)(struct sk_buff *, struct netlink_callback *, int, struct tc_action *);
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};
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int tcf_hash_search(struct tc_action *a, u32 index);
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void tcf_hash_destroy(struct tc_action *a);
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u32 tcf_hash_new_index(struct tcf_hashinfo *hinfo);
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int tcf_hash_check(u32 index, struct tc_action *a, int bind);
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int tcf_hash_create(u32 index, struct nlattr *est, struct tc_action *a,
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int size, int bind);
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void tcf_hash_cleanup(struct tc_action *a, struct nlattr *est);
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void tcf_hash_insert(struct tc_action *a);
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int __tcf_hash_release(struct tc_action *a, bool bind, bool strict);
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static inline int tcf_hash_release(struct tc_action *a, bool bind)
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{
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return __tcf_hash_release(a, bind, false);
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}
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int tcf_register_action(struct tc_action_ops *a, unsigned int mask);
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int tcf_unregister_action(struct tc_action_ops *a);
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int tcf_action_destroy(struct list_head *actions, int bind);
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int tcf_action_exec(struct sk_buff *skb, const struct list_head *actions,
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struct tcf_result *res);
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int tcf_action_init(struct net *net, struct nlattr *nla,
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struct nlattr *est, char *n, int ovr,
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int bind, struct list_head *);
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struct tc_action *tcf_action_init_1(struct net *net, struct nlattr *nla,
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struct nlattr *est, char *n, int ovr,
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int bind);
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int tcf_action_dump(struct sk_buff *skb, struct list_head *, int, int);
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int tcf_action_dump_old(struct sk_buff *skb, struct tc_action *a, int, int);
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int tcf_action_dump_1(struct sk_buff *skb, struct tc_action *a, int, int);
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int tcf_action_copy_stats(struct sk_buff *, struct tc_action *, int);
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#endif /* CONFIG_NET_CLS_ACT */
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#endif
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