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Hello,
On Fri, 12 Aug 2022, sunsuwan wrote:
> We founf a possible UAF if rmmod pe_sid or schedule,
> when packages in hook and get pe or sched.
>
> Signed-off-by: sunsuwan <sunsuwan3@xxxxxxxxxx>
> Signed-off-by: chenzhen <chenzhen126@xxxxxxxxxx>
> ---
> net/netfilter/ipvs/ip_vs_core.c | 6 ++++++
> net/netfilter/ipvs/ip_vs_ctl.c | 3 +++
> net/netfilter/ipvs/ip_vs_dh.c | 2 ++
> 3 files changed, 11 insertions(+)
>
> diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
> index 51ad557a525b..d289f184d5c1 100644
> --- a/net/netfilter/ipvs/ip_vs_core.c
> +++ b/net/netfilter/ipvs/ip_vs_core.c
> @@ -235,7 +235,9 @@ ip_vs_conn_fill_param_persist(const struct ip_vs_service
> *svc,
> {
> ip_vs_conn_fill_param(svc->ipvs, svc->af, protocol, caddr, cport, vaddr,
> vport, p);
> + rcu_read_lock();
> p->pe = rcu_dereference(svc->pe);
> + rcu_read_unlock();
Hm, in theory, here we are under rcu_read_lock, see
nf_hook() in include/linux/netfilter.h. IPVS processes packets
by using netfilter hooks. So, IPVS scheduling is under this lock
too and ip_vs_conn_fill_param_persist() is part of the scheduling
call flow.
> if (p->pe && p->pe->fill_param)
> return p->pe->fill_param(p, skb);
>
> @@ -346,7 +348,9 @@ ip_vs_sched_persist(struct ip_vs_service *svc,
> * template is not available.
> * return *ignored=0 i.e. ICMP and NF_DROP
> */
> + rcu_read_lock();
> sched = rcu_dereference(svc->scheduler);
> + rcu_read_unlock();
Scheduling from hook...
> if (sched) {
> /* read svc->sched_data after svc->scheduler */
> smp_rmb();
> @@ -521,7 +525,9 @@ ip_vs_schedule(struct ip_vs_service *svc, struct sk_buff
> *skb,
> return NULL;
> }
>
> + rcu_read_lock();
> sched = rcu_dereference(svc->scheduler);
> + rcu_read_unlock();
Scheduling from hook...
> if (sched) {
> /* read svc->sched_data after svc->scheduler */
> smp_rmb();
> diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
> index efab2b06d373..91e568028001 100644
> --- a/net/netfilter/ipvs/ip_vs_ctl.c
> +++ b/net/netfilter/ipvs/ip_vs_ctl.c
> @@ -580,6 +580,7 @@ bool ip_vs_has_real_service(struct netns_ipvs *ipvs, int
> af, __u16 protocol,
> /* Check for "full" addressed entries */
> hash = ip_vs_rs_hashkey(af, daddr, dport);
>
> + rcu_read_lock();
ip_vs_has_real_service() is called by ip_vs_out_hook()
> hlist_for_each_entry_rcu(dest, &ipvs->rs_table[hash], d_list) {
> if (dest->port == dport &&
> dest->af == af &&
> @@ -587,9 +588,11 @@ bool ip_vs_has_real_service(struct netns_ipvs *ipvs, int
> af, __u16 protocol,
> (dest->protocol == protocol || dest->vfwmark) &&
> IP_VS_DFWD_METHOD(dest) == IP_VS_CONN_F_MASQ) {
> /* HIT */
> + rcu_read_unlock();
> return true;
> }
> }
> + rcu_read_unlock();
>
> return false;
> }
> diff --git a/net/netfilter/ipvs/ip_vs_dh.c b/net/netfilter/ipvs/ip_vs_dh.c
> index 5e6ec32aff2b..3e4b9607172b 100644
> --- a/net/netfilter/ipvs/ip_vs_dh.c
> +++ b/net/netfilter/ipvs/ip_vs_dh.c
> @@ -219,7 +219,9 @@ ip_vs_dh_schedule(struct ip_vs_service *svc, const struct
> sk_buff *skb,
> IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
>
> s = (struct ip_vs_dh_state *) svc->sched_data;
> + rcu_read_lock();
> dest = ip_vs_dh_get(svc->af, s, &iph->daddr);
> + rcu_read_unlock();
Scheduling from hook...
> if (!dest
> || !(dest->flags & IP_VS_DEST_F_AVAILABLE)
> || atomic_read(&dest->weight) <= 0
> --
> 2.30.0
So, all above places are already under rcu_read_lock.
If you see some real problem, we should track it somehow.
As for the PEs, they are protected as follows:
- svc holds 1 pe_sip module refcnt (svc->pe), from ip_vs_pe_getbyname()
- every conn can get 1 pe_sip module refcnt (cp->pe): ip_vs_pe_get()
- when last conn releases pe_sip with ip_vs_pe_put() there
can be flying packets, so we have synchronize_rcu() in
ip_vs_sip_cleanup()
Regards
--
Julian Anastasov <ja@xxxxxx>
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