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netfilter: nfnetlink: nfnetlink_unicast() reports EAGAIN instead of ENOBUFS 

[ Upstream commit ee921183557af39c1a0475f982d43b0fcac25e2e ]

Frontend callback reports EAGAIN to nfnetlink to retry a command, this
is used to signal that module autoloading is required. Unfortunately,
nlmsg_unicast() reports EAGAIN in case the receiver socket buffer gets
full, so it enters a busy-loop.

This patch updates nfnetlink_unicast() to turn EAGAIN into ENOBUFS and
to use nlmsg_unicast(). Remove the flags field in nfnetlink_unicast()
since this is always MSG_DONTWAIT in the existing code which is exactly
what nlmsg_unicast() passes to netlink_unicast() as parameter.

Fixes: 96518518cc ("netfilter: add nftables")
Reported-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Pablo Neira Ayuso 2020-08-23 13:55:36 +02:00 committed by Greg Kroah-Hartman
parent 498575898e
commit 9ff9f74ed4
5 changed files with 40 additions and 40 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/linux/netfilter/nfnetlink.h
View File

@ -43,8 +43,7 @@ int nfnetlink_has_listeners(struct net *net, unsigned int group);
int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 portid,
unsigned int group, int echo, gfp_t flags);
int nfnetlink_set_err(struct net *net, u32 portid, u32 group, int error);
int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u32 portid,
int flags);
int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u32 portid);
static inline u16 nfnl_msg_type(u8 subsys, u8 msg_type)
{

61
net/netfilter/nf_tables_api.c
View File

@ -744,11 +744,11 @@ static int nf_tables_gettable(struct net *net, struct sock *nlsk,
nlh->nlmsg_seq, NFT_MSG_NEWTABLE, 0,
family, table);
if (err < 0)
goto err;
goto err_fill_table_info;
return nlmsg_unicast(nlsk, skb2, NETLINK_CB(skb).portid);
return nfnetlink_unicast(skb2, net, NETLINK_CB(skb).portid);
err:
err_fill_table_info:
kfree_skb(skb2);
return err;
}
@ -1443,11 +1443,11 @@ static int nf_tables_getchain(struct net *net, struct sock *nlsk,
nlh->nlmsg_seq, NFT_MSG_NEWCHAIN, 0,
family, table, chain);
if (err < 0)
goto err;
goto err_fill_chain_info;
return nlmsg_unicast(nlsk, skb2, NETLINK_CB(skb).portid);
return nfnetlink_unicast(skb2, net, NETLINK_CB(skb).portid);
err:
err_fill_chain_info:
kfree_skb(skb2);
return err;
}
@ -2622,11 +2622,11 @@ static int nf_tables_getrule(struct net *net, struct sock *nlsk,
nlh->nlmsg_seq, NFT_MSG_NEWRULE, 0,
family, table, chain, rule, NULL);
if (err < 0)
goto err;
goto err_fill_rule_info;
return nlmsg_unicast(nlsk, skb2, NETLINK_CB(skb).portid);
return nfnetlink_unicast(skb2, net, NETLINK_CB(skb).portid);
err:
err_fill_rule_info:
kfree_skb(skb2);
return err;
}
@ -3526,11 +3526,11 @@ static int nf_tables_getset(struct net *net, struct sock *nlsk,
err = nf_tables_fill_set(skb2, &ctx, set, NFT_MSG_NEWSET, 0);
if (err < 0)
goto err;
goto err_fill_set_info;
return nlmsg_unicast(nlsk, skb2, NETLINK_CB(skb).portid);
return nfnetlink_unicast(skb2, net, NETLINK_CB(skb).portid);
err:
err_fill_set_info:
kfree_skb(skb2);
return err;
}
@ -4305,24 +4305,18 @@ static int nft_get_set_elem(struct nft_ctx *ctx, struct nft_set *set,
err = -ENOMEM;
skb = nlmsg_new(NLMSG_GOODSIZE, GFP_ATOMIC);
if (skb == NULL)
goto err1;
return err;
err = nf_tables_fill_setelem_info(skb, ctx, ctx->seq, ctx->portid,
NFT_MSG_NEWSETELEM, 0, set, &elem);
if (err < 0)
goto err2;
goto err_fill_setelem;
err = nfnetlink_unicast(skb, ctx->net, ctx->portid, MSG_DONTWAIT);
/* This avoids a loop in nfnetlink. */
if (err < 0)
goto err1;
return nfnetlink_unicast(skb, ctx->net, ctx->portid);
return 0;
err2:
err_fill_setelem:
kfree_skb(skb);
err1:
/* this avoids a loop in nfnetlink. */
return err == -EAGAIN ? -ENOBUFS : err;
return err;
}
/* called with rcu_read_lock held */
@ -5499,10 +5493,11 @@ static int nf_tables_getobj(struct net *net, struct sock *nlsk,
nlh->nlmsg_seq, NFT_MSG_NEWOBJ, 0,
family, table, obj, reset);
if (err < 0)
goto err;
goto err_fill_obj_info;
return nlmsg_unicast(nlsk, skb2, NETLINK_CB(skb).portid);
err:
return nfnetlink_unicast(skb2, net, NETLINK_CB(skb).portid);
err_fill_obj_info:
kfree_skb(skb2);
return err;
}
@ -6174,10 +6169,11 @@ static int nf_tables_getflowtable(struct net *net, struct sock *nlsk,
NFT_MSG_NEWFLOWTABLE, 0, family,
flowtable);
if (err < 0)
goto err;
goto err_fill_flowtable_info;
return nlmsg_unicast(nlsk, skb2, NETLINK_CB(skb).portid);
err:
return nfnetlink_unicast(skb2, net, NETLINK_CB(skb).portid);
err_fill_flowtable_info:
kfree_skb(skb2);
return err;
}
@ -6338,10 +6334,11 @@ static int nf_tables_getgen(struct net *net, struct sock *nlsk,
err = nf_tables_fill_gen_info(skb2, net, NETLINK_CB(skb).portid,
nlh->nlmsg_seq);
if (err < 0)
goto err;
goto err_fill_gen_info;
return nlmsg_unicast(nlsk, skb2, NETLINK_CB(skb).portid);
err:
return nfnetlink_unicast(skb2, net, NETLINK_CB(skb).portid);
err_fill_gen_info:
kfree_skb(skb2);
return err;
}

11
net/netfilter/nfnetlink.c
View File

@ -148,10 +148,15 @@ int nfnetlink_set_err(struct net *net, u32 portid, u32 group, int error)
}
EXPORT_SYMBOL_GPL(nfnetlink_set_err);
int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u32 portid,
int flags)
int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u32 portid)
{
return netlink_unicast(net->nfnl, skb, portid, flags);
int err;
err = nlmsg_unicast(net->nfnl, skb, portid);
if (err == -EAGAIN)
err = -ENOBUFS;
return err;
}
EXPORT_SYMBOL_GPL(nfnetlink_unicast);

3
net/netfilter/nfnetlink_log.c
View File

@ -356,8 +356,7 @@ __nfulnl_send(struct nfulnl_instance *inst)
goto out;
}
}
nfnetlink_unicast(inst->skb, inst->net, inst->peer_portid,
MSG_DONTWAIT);
nfnetlink_unicast(inst->skb, inst->net, inst->peer_portid);
out:
inst->qlen = 0;
inst->skb = NULL;

2
net/netfilter/nfnetlink_queue.c
View File

@ -681,7 +681,7 @@ __nfqnl_enqueue_packet(struct net *net, struct nfqnl_instance *queue,
*packet_id_ptr = htonl(entry->id);
/* nfnetlink_unicast will either free the nskb or add it to a socket */
err = nfnetlink_unicast(nskb, net, queue->peer_portid, MSG_DONTWAIT);
err = nfnetlink_unicast(nskb, net, queue->peer_portid);
if (err < 0) {
if (queue->flags & NFQA_CFG_F_FAIL_OPEN) {
failopen = 1;