From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: [PATCH 3/9] netfilter: helper: Add the rcu lock when call __nf_conntrack_helper_find Date: Fri, 14 Apr 2017 02:26:45 +0200 Message-ID: <1492129611-29336-4-git-send-email-pablo@netfilter.org> References: <1492129611-29336-1-git-send-email-pablo@netfilter.org> Cc: davem@davemloft.net, netdev@vger.kernel.org To: netfilter-devel@vger.kernel.org Return-path: In-Reply-To: <1492129611-29336-1-git-send-email-pablo@netfilter.org> Sender: netfilter-devel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Gao Feng When invoke __nf_conntrack_helper_find, it needs the rcu lock to protect the helper module which would not be unloaded. Now there are two caller nf_conntrack_helper_try_module_get and ctnetlink_create_expect which don't hold rcu lock. And the other callers left like ctnetlink_change_helper, ctnetlink_create_conntrack, and ctnetlink_glue_attach_expect, they already hold the rcu lock or spin_lock_bh. Remove the rcu lock in functions nf_ct_helper_expectfn_find_by_name and nf_ct_helper_expectfn_find_by_symbol. Because they return one pointer which needs rcu lock, so their caller should hold the rcu lock, not in these two functions. Signed-off-by: Gao Feng Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_conntrack_helper.c | 17 ++++++++++++----- net/netfilter/nf_conntrack_netlink.c | 10 ++++++++-- 2 files changed, 20 insertions(+), 7 deletions(-) diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c index 6dc44d9b4190..4eeb3418366a 100644 --- a/net/netfilter/nf_conntrack_helper.c +++ b/net/netfilter/nf_conntrack_helper.c @@ -158,16 +158,25 @@ nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum) { struct nf_conntrack_helper *h; + rcu_read_lock(); + h = __nf_conntrack_helper_find(name, l3num, protonum); #ifdef CONFIG_MODULES if (h == NULL) { - if (request_module("nfct-helper-%s", name) == 0) + rcu_read_unlock(); + if (request_module("nfct-helper-%s", name) == 0) { + rcu_read_lock(); h = __nf_conntrack_helper_find(name, l3num, protonum); + } else { + return h; + } } #endif if (h != NULL && !try_module_get(h->me)) h = NULL; + rcu_read_unlock(); + return h; } EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get); @@ -311,38 +320,36 @@ void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n) } EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister); +/* Caller should hold the rcu lock */ struct nf_ct_helper_expectfn * nf_ct_helper_expectfn_find_by_name(const char *name) { struct nf_ct_helper_expectfn *cur; bool found = false; - rcu_read_lock(); list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) { if (!strcmp(cur->name, name)) { found = true; break; } } - rcu_read_unlock(); return found ? cur : NULL; } EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_name); +/* Caller should hold the rcu lock */ struct nf_ct_helper_expectfn * nf_ct_helper_expectfn_find_by_symbol(const void *symbol) { struct nf_ct_helper_expectfn *cur; bool found = false; - rcu_read_lock(); list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) { if (cur->expectfn == symbol) { found = true; break; } } - rcu_read_unlock(); return found ? cur : NULL; } EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol); diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c index 59ee27deb9a0..06d28ac663df 100644 --- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -3133,23 +3133,27 @@ ctnetlink_create_expect(struct net *net, return -ENOENT; ct = nf_ct_tuplehash_to_ctrack(h); + rcu_read_lock(); if (cda[CTA_EXPECT_HELP_NAME]) { const char *helpname = nla_data(cda[CTA_EXPECT_HELP_NAME]); helper = __nf_conntrack_helper_find(helpname, u3, nf_ct_protonum(ct)); if (helper == NULL) { + rcu_read_unlock(); #ifdef CONFIG_MODULES if (request_module("nfct-helper-%s", helpname) < 0) { err = -EOPNOTSUPP; goto err_ct; } + rcu_read_lock(); helper = __nf_conntrack_helper_find(helpname, u3, nf_ct_protonum(ct)); if (helper) { err = -EAGAIN; - goto err_ct; + goto err_rcu; } + rcu_read_unlock(); #endif err = -EOPNOTSUPP; goto err_ct; @@ -3159,11 +3163,13 @@ ctnetlink_create_expect(struct net *net, exp = ctnetlink_alloc_expect(cda, ct, helper, &tuple, &mask); if (IS_ERR(exp)) { err = PTR_ERR(exp); - goto err_ct; + goto err_rcu; } err = nf_ct_expect_related_report(exp, portid, report); nf_ct_expect_put(exp); +err_rcu: + rcu_read_unlock(); err_ct: nf_ct_put(ct); return err; -- 2.1.4