From 044462242abc77a1e5e9cd33a9d0f4277521a70a Mon Sep 17 00:00:00 2001 From: Phil Sutter Date: Fri, 9 Aug 2024 15:07:30 +0200 Subject: netfilter: nf_tables: Audit log dump reset after the fact [ Upstream commit e0b6648b0446e59522819c75ba1dcb09e68d3e94 ] In theory, dumpreset may fail and invalidate the preceeding log message. Fix this and use the occasion to prepare for object reset locking, which benefits from a few unrelated changes: * Add an early call to nfnetlink_unicast if not resetting which effectively skips the audit logging but also unindents it. * Extract the table's name from the netlink attribute (which is verified via earlier table lookup) to not rely upon validity of the looked up table pointer. * Do not use local variable family, it will vanish. Fixes: 8e6cf365e1d5 ("audit: log nftables configuration change events") Signed-off-by: Phil Sutter Reviewed-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin --- net/netfilter/nf_tables_api.c | 28 +++++++++++++--------------- 1 file changed, 13 insertions(+), 15 deletions(-) (limited to 'net/netfilter/nf_tables_api.c') diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 91cc3a81ba8f..7ae055521cf3 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -8012,6 +8012,7 @@ static int nf_tables_dump_obj_done(struct netlink_callback *cb) static int nf_tables_getobj(struct sk_buff *skb, const struct nfnl_info *info, const struct nlattr * const nla[]) { + const struct nftables_pernet *nft_net = nft_pernet(info->net); struct netlink_ext_ack *extack = info->extack; u8 genmask = nft_genmask_cur(info->net); u8 family = info->nfmsg->nfgen_family; @@ -8021,6 +8022,7 @@ static int nf_tables_getobj(struct sk_buff *skb, const struct nfnl_info *info, struct sk_buff *skb2; bool reset = false; u32 objtype; + char *buf; int err; if (info->nlh->nlmsg_flags & NLM_F_DUMP) { @@ -8059,27 +8061,23 @@ static int nf_tables_getobj(struct sk_buff *skb, const struct nfnl_info *info, if (NFNL_MSG_TYPE(info->nlh->nlmsg_type) == NFT_MSG_GETOBJ_RESET) reset = true; - if (reset) { - const struct nftables_pernet *nft_net; - char *buf; - - nft_net = nft_pernet(net); - buf = kasprintf(GFP_ATOMIC, "%s:%u", table->name, nft_net->base_seq); - - audit_log_nfcfg(buf, - family, - 1, - AUDIT_NFT_OP_OBJ_RESET, - GFP_ATOMIC); - kfree(buf); - } - err = nf_tables_fill_obj_info(skb2, net, NETLINK_CB(skb).portid, info->nlh->nlmsg_seq, NFT_MSG_NEWOBJ, 0, family, table, obj, reset); if (err < 0) goto err_fill_obj_info; + if (!reset) + return nfnetlink_unicast(skb2, net, NETLINK_CB(skb).portid); + + buf = kasprintf(GFP_ATOMIC, "%.*s:%u", + nla_len(nla[NFTA_OBJ_TABLE]), + (char *)nla_data(nla[NFTA_OBJ_TABLE]), + nft_net->base_seq); + audit_log_nfcfg(buf, info->nfmsg->nfgen_family, 1, + AUDIT_NFT_OP_OBJ_RESET, GFP_ATOMIC); + kfree(buf); + return nfnetlink_unicast(skb2, net, NETLINK_CB(skb).portid); err_fill_obj_info: -- cgit v1.2.3 From bf031525a8b9e2857d40f20ca194279a5b04104e Mon Sep 17 00:00:00 2001 From: Phil Sutter Date: Fri, 9 Aug 2024 15:07:31 +0200 Subject: netfilter: nf_tables: Introduce nf_tables_getobj_single [ Upstream commit 69fc3e9e90f1afc11f4015e6b75d18ab9acee348 ] Outsource the reply skb preparation for non-dump getrule requests into a distinct function. Prep work for object reset locking. Signed-off-by: Phil Sutter Reviewed-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Stable-dep-of: bd662c4218f9 ("netfilter: nf_tables: Add locking for NFT_MSG_GETOBJ_RESET requests") Signed-off-by: Sasha Levin --- net/netfilter/nf_tables_api.c | 75 +++++++++++++++++++++++++------------------ 1 file changed, 44 insertions(+), 31 deletions(-) (limited to 'net/netfilter/nf_tables_api.c') diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 7ae055521cf3..2f32db2a09fe 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -8009,10 +8009,10 @@ static int nf_tables_dump_obj_done(struct netlink_callback *cb) } /* called with rcu_read_lock held */ -static int nf_tables_getobj(struct sk_buff *skb, const struct nfnl_info *info, - const struct nlattr * const nla[]) +static struct sk_buff * +nf_tables_getobj_single(u32 portid, const struct nfnl_info *info, + const struct nlattr * const nla[], bool reset) { - const struct nftables_pernet *nft_net = nft_pernet(info->net); struct netlink_ext_ack *extack = info->extack; u8 genmask = nft_genmask_cur(info->net); u8 family = info->nfmsg->nfgen_family; @@ -8020,52 +8020,69 @@ static int nf_tables_getobj(struct sk_buff *skb, const struct nfnl_info *info, struct net *net = info->net; struct nft_object *obj; struct sk_buff *skb2; - bool reset = false; u32 objtype; - char *buf; int err; - if (info->nlh->nlmsg_flags & NLM_F_DUMP) { - struct netlink_dump_control c = { - .start = nf_tables_dump_obj_start, - .dump = nf_tables_dump_obj, - .done = nf_tables_dump_obj_done, - .module = THIS_MODULE, - .data = (void *)nla, - }; - - return nft_netlink_dump_start_rcu(info->sk, skb, info->nlh, &c); - } - if (!nla[NFTA_OBJ_NAME] || !nla[NFTA_OBJ_TYPE]) - return -EINVAL; + return ERR_PTR(-EINVAL); table = nft_table_lookup(net, nla[NFTA_OBJ_TABLE], family, genmask, 0); if (IS_ERR(table)) { NL_SET_BAD_ATTR(extack, nla[NFTA_OBJ_TABLE]); - return PTR_ERR(table); + return ERR_CAST(table); } objtype = ntohl(nla_get_be32(nla[NFTA_OBJ_TYPE])); obj = nft_obj_lookup(net, table, nla[NFTA_OBJ_NAME], objtype, genmask); if (IS_ERR(obj)) { NL_SET_BAD_ATTR(extack, nla[NFTA_OBJ_NAME]); - return PTR_ERR(obj); + return ERR_CAST(obj); } skb2 = alloc_skb(NLMSG_GOODSIZE, GFP_ATOMIC); if (!skb2) - return -ENOMEM; + return ERR_PTR(-ENOMEM); + + err = nf_tables_fill_obj_info(skb2, net, portid, + info->nlh->nlmsg_seq, NFT_MSG_NEWOBJ, 0, + family, table, obj, reset); + if (err < 0) { + kfree_skb(skb2); + return ERR_PTR(err); + } + + return skb2; +} + +static int nf_tables_getobj(struct sk_buff *skb, const struct nfnl_info *info, + const struct nlattr * const nla[]) +{ + struct nftables_pernet *nft_net = nft_pernet(info->net); + u32 portid = NETLINK_CB(skb).portid; + struct net *net = info->net; + struct sk_buff *skb2; + bool reset = false; + char *buf; + + if (info->nlh->nlmsg_flags & NLM_F_DUMP) { + struct netlink_dump_control c = { + .start = nf_tables_dump_obj_start, + .dump = nf_tables_dump_obj, + .done = nf_tables_dump_obj_done, + .module = THIS_MODULE, + .data = (void *)nla, + }; + + return nft_netlink_dump_start_rcu(info->sk, skb, info->nlh, &c); + } if (NFNL_MSG_TYPE(info->nlh->nlmsg_type) == NFT_MSG_GETOBJ_RESET) reset = true; - err = nf_tables_fill_obj_info(skb2, net, NETLINK_CB(skb).portid, - info->nlh->nlmsg_seq, NFT_MSG_NEWOBJ, 0, - family, table, obj, reset); - if (err < 0) - goto err_fill_obj_info; + skb2 = nf_tables_getobj_single(portid, info, nla, reset); + if (IS_ERR(skb2)) + return PTR_ERR(skb2); if (!reset) return nfnetlink_unicast(skb2, net, NETLINK_CB(skb).portid); @@ -8078,11 +8095,7 @@ static int nf_tables_getobj(struct sk_buff *skb, const struct nfnl_info *info, AUDIT_NFT_OP_OBJ_RESET, GFP_ATOMIC); kfree(buf); - return nfnetlink_unicast(skb2, net, NETLINK_CB(skb).portid); - -err_fill_obj_info: - kfree_skb(skb2); - return err; + return nfnetlink_unicast(skb2, net, portid); } static void nft_obj_destroy(const struct nft_ctx *ctx, struct nft_object *obj) -- cgit v1.2.3 From eb83dfb68cf111f839943fc6e12d821097f6d8c1 Mon Sep 17 00:00:00 2001 From: Phil Sutter Date: Fri, 9 Aug 2024 15:07:32 +0200 Subject: netfilter: nf_tables: Add locking for NFT_MSG_GETOBJ_RESET requests [ Upstream commit bd662c4218f9648e888bebde9468146965f3f8a0 ] Objects' dump callbacks are not concurrency-safe per-se with reset bit set. If two CPUs perform a reset at the same time, at least counter and quota objects suffer from value underrun. Prevent this by introducing dedicated locking callbacks for nfnetlink and the asynchronous dump handling to serialize access. Fixes: 43da04a593d8 ("netfilter: nf_tables: atomic dump and reset for stateful objects") Signed-off-by: Phil Sutter Reviewed-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin --- net/netfilter/nf_tables_api.c | 72 +++++++++++++++++++++++++++++++++++-------- 1 file changed, 59 insertions(+), 13 deletions(-) (limited to 'net/netfilter/nf_tables_api.c') diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 2f32db2a09fe..41d7faeb101c 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -7977,6 +7977,19 @@ cont: return skb->len; } +static int nf_tables_dumpreset_obj(struct sk_buff *skb, + struct netlink_callback *cb) +{ + struct nftables_pernet *nft_net = nft_pernet(sock_net(skb->sk)); + int ret; + + mutex_lock(&nft_net->commit_mutex); + ret = nf_tables_dump_obj(skb, cb); + mutex_unlock(&nft_net->commit_mutex); + + return ret; +} + static int nf_tables_dump_obj_start(struct netlink_callback *cb) { struct nft_obj_dump_ctx *ctx = (void *)cb->ctx; @@ -7993,12 +8006,18 @@ static int nf_tables_dump_obj_start(struct netlink_callback *cb) if (nla[NFTA_OBJ_TYPE]) ctx->type = ntohl(nla_get_be32(nla[NFTA_OBJ_TYPE])); - if (NFNL_MSG_TYPE(cb->nlh->nlmsg_type) == NFT_MSG_GETOBJ_RESET) - ctx->reset = true; - return 0; } +static int nf_tables_dumpreset_obj_start(struct netlink_callback *cb) +{ + struct nft_obj_dump_ctx *ctx = (void *)cb->ctx; + + ctx->reset = true; + + return nf_tables_dump_obj_start(cb); +} + static int nf_tables_dump_obj_done(struct netlink_callback *cb) { struct nft_obj_dump_ctx *ctx = (void *)cb->ctx; @@ -8057,18 +8076,43 @@ nf_tables_getobj_single(u32 portid, const struct nfnl_info *info, static int nf_tables_getobj(struct sk_buff *skb, const struct nfnl_info *info, const struct nlattr * const nla[]) +{ + u32 portid = NETLINK_CB(skb).portid; + struct sk_buff *skb2; + + if (info->nlh->nlmsg_flags & NLM_F_DUMP) { + struct netlink_dump_control c = { + .start = nf_tables_dump_obj_start, + .dump = nf_tables_dump_obj, + .done = nf_tables_dump_obj_done, + .module = THIS_MODULE, + .data = (void *)nla, + }; + + return nft_netlink_dump_start_rcu(info->sk, skb, info->nlh, &c); + } + + skb2 = nf_tables_getobj_single(portid, info, nla, false); + if (IS_ERR(skb2)) + return PTR_ERR(skb2); + + return nfnetlink_unicast(skb2, info->net, portid); +} + +static int nf_tables_getobj_reset(struct sk_buff *skb, + const struct nfnl_info *info, + const struct nlattr * const nla[]) { struct nftables_pernet *nft_net = nft_pernet(info->net); u32 portid = NETLINK_CB(skb).portid; struct net *net = info->net; struct sk_buff *skb2; - bool reset = false; char *buf; if (info->nlh->nlmsg_flags & NLM_F_DUMP) { struct netlink_dump_control c = { - .start = nf_tables_dump_obj_start, - .dump = nf_tables_dump_obj, + .start = nf_tables_dumpreset_obj_start, + .dump = nf_tables_dumpreset_obj, .done = nf_tables_dump_obj_done, .module = THIS_MODULE, .data = (void *)nla, @@ -8077,16 +8121,18 @@ static int nf_tables_getobj(struct sk_buff *skb, const struct nfnl_info *info, return nft_netlink_dump_start_rcu(info->sk, skb, info->nlh, &c); } - if (NFNL_MSG_TYPE(info->nlh->nlmsg_type) == NFT_MSG_GETOBJ_RESET) - reset = true; + if (!try_module_get(THIS_MODULE)) + return -EINVAL; + rcu_read_unlock(); + mutex_lock(&nft_net->commit_mutex); + skb2 = nf_tables_getobj_single(portid, info, nla, true); + mutex_unlock(&nft_net->commit_mutex); + rcu_read_lock(); + module_put(THIS_MODULE); - skb2 = nf_tables_getobj_single(portid, info, nla, reset); if (IS_ERR(skb2)) return PTR_ERR(skb2); - if (!reset) - return nfnetlink_unicast(skb2, net, NETLINK_CB(skb).portid); - buf = kasprintf(GFP_ATOMIC, "%.*s:%u", nla_len(nla[NFTA_OBJ_TABLE]), (char *)nla_data(nla[NFTA_OBJ_TABLE]), @@ -9378,7 +9424,7 @@ static const struct nfnl_callback nf_tables_cb[NFT_MSG_MAX] = { .policy = nft_obj_policy, }, [NFT_MSG_GETOBJ_RESET] = { - .call = nf_tables_getobj, + .call = nf_tables_getobj_reset, .type = NFNL_CB_RCU, .attr_count = NFTA_OBJ_MAX, .policy = nft_obj_policy, -- cgit v1.2.3