[SRU][F][PATCH v2 1/1] netfilter: nf_tables: use timestamp to check for set element timeout
Massimiliano Pellizzer
massimiliano.pellizzer at canonical.com
Mon Sep 2 14:37:45 UTC 2024
From: Pablo Neira Ayuso <pablo at netfilter.org>
commit 7395dfacfff65e9938ac0889dafa1ab01e987d15 upstream
Add a timestamp field at the beginning of the transaction, store it
in the nftables per-netns area.
Update set backend .insert, .deactivate and sync gc path to use the
timestamp, this avoids that an element expires while control plane
transaction is still unfinished.
.lookup and .update, which are used from packet path, still use the
current time to check if the element has expired. And .get path and dump
also since this runs lockless under rcu read size lock. Then, there is
async gc which also needs to check the current time since it runs
asynchronously from a workqueue.
[ NB: rbtree GC updates has been excluded because GC is asynchronous. ]
Fixes: c3e1b005ed1c ("netfilter: nf_tables: add set element timeout support")
Signed-off-by: Pablo Neira Ayuso <pablo at netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
(backported from commit eaf1a29ea5d7dba8e84e9e9f3b3f47d0cd540bfe linux-5.4.y)
[mpellizzer: solved a merge conflict due to a variable declaration which
does not affect the patch]
CVE-2024-27397
Signed-off-by: Massimiliano Pellizzer <massimiliano.pellizzer at canonical.com>
---
include/net/netfilter/nf_tables.h | 21 +++++++++++++++++++--
net/netfilter/nf_tables_api.c | 1 +
net/netfilter/nft_set_hash.c | 8 +++++++-
net/netfilter/nft_set_rbtree.c | 6 ++++--
4 files changed, 31 insertions(+), 5 deletions(-)
diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 74ee59746f6b..a7672b8a909e 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -13,6 +13,7 @@
#include <net/netfilter/nf_flow_table.h>
#include <net/netlink.h>
#include <net/flow_offload.h>
+#include <net/netns/generic.h>
struct module;
@@ -656,10 +657,16 @@ static inline struct nft_expr *nft_set_ext_expr(const struct nft_set_ext *ext)
return nft_set_ext(ext, NFT_SET_EXT_EXPR);
}
-static inline bool nft_set_elem_expired(const struct nft_set_ext *ext)
+static inline bool __nft_set_elem_expired(const struct nft_set_ext *ext,
+ u64 tstamp)
{
return nft_set_ext_exists(ext, NFT_SET_EXT_EXPIRATION) &&
- time_is_before_eq_jiffies64(*nft_set_ext_expiration(ext));
+ time_after_eq64(tstamp, *nft_set_ext_expiration(ext));
+}
+
+static inline bool nft_set_elem_expired(const struct nft_set_ext *ext)
+{
+ return __nft_set_elem_expired(ext, get_jiffies_64());
}
static inline struct nft_set_ext *nft_set_elem_ext(const struct nft_set *set,
@@ -1488,9 +1495,19 @@ struct nftables_pernet {
struct list_head module_list;
struct list_head notify_list;
struct mutex commit_mutex;
+ u64 tstamp;
unsigned int base_seq;
u8 validate_state;
unsigned int gc_seq;
};
+extern unsigned int nf_tables_net_id;
+
+static inline u64 nft_net_tstamp(const struct net *net)
+{
+ struct nftables_pernet *nft_net = net_generic(net, nf_tables_net_id);
+
+ return nft_net->tstamp;
+}
+
#endif /* _NET_NF_TABLES_H */
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 10e7d8e9df04..14f730a371bd 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -7810,6 +7810,7 @@ static bool nf_tables_valid_genid(struct net *net, u32 genid)
bool genid_ok;
mutex_lock(&nft_net->commit_mutex);
+ nft_net->tstamp = get_jiffies_64();
genid_ok = genid == 0 || nft_net->base_seq == genid;
if (!genid_ok)
diff --git a/net/netfilter/nft_set_hash.c b/net/netfilter/nft_set_hash.c
index 7f49c6c37c94..92ab00d17337 100644
--- a/net/netfilter/nft_set_hash.c
+++ b/net/netfilter/nft_set_hash.c
@@ -38,6 +38,7 @@ struct nft_rhash_cmp_arg {
const struct nft_set *set;
const u32 *key;
u8 genmask;
+ u64 tstamp;
};
static inline u32 nft_rhash_key(const void *data, u32 len, u32 seed)
@@ -64,7 +65,7 @@ static inline int nft_rhash_cmp(struct rhashtable_compare_arg *arg,
return 1;
if (nft_set_elem_is_dead(&he->ext))
return 1;
- if (nft_set_elem_expired(&he->ext))
+ if (__nft_set_elem_expired(&he->ext, x->tstamp))
return 1;
if (!nft_set_elem_active(&he->ext, x->genmask))
return 1;
@@ -88,6 +89,7 @@ static bool nft_rhash_lookup(const struct net *net, const struct nft_set *set,
.genmask = nft_genmask_cur(net),
.set = set,
.key = key,
+ .tstamp = get_jiffies_64(),
};
he = rhashtable_lookup(&priv->ht, &arg, nft_rhash_params);
@@ -106,6 +108,7 @@ static void *nft_rhash_get(const struct net *net, const struct nft_set *set,
.genmask = nft_genmask_cur(net),
.set = set,
.key = elem->key.val.data,
+ .tstamp = get_jiffies_64(),
};
he = rhashtable_lookup(&priv->ht, &arg, nft_rhash_params);
@@ -129,6 +132,7 @@ static bool nft_rhash_update(struct nft_set *set, const u32 *key,
.genmask = NFT_GENMASK_ANY,
.set = set,
.key = key,
+ .tstamp = get_jiffies_64(),
};
he = rhashtable_lookup(&priv->ht, &arg, nft_rhash_params);
@@ -172,6 +176,7 @@ static int nft_rhash_insert(const struct net *net, const struct nft_set *set,
.genmask = nft_genmask_next(net),
.set = set,
.key = elem->key.val.data,
+ .tstamp = nft_net_tstamp(net),
};
struct nft_rhash_elem *prev;
@@ -214,6 +219,7 @@ static void *nft_rhash_deactivate(const struct net *net,
.genmask = nft_genmask_next(net),
.set = set,
.key = elem->key.val.data,
+ .tstamp = nft_net_tstamp(net),
};
rcu_read_lock();
diff --git a/net/netfilter/nft_set_rbtree.c b/net/netfilter/nft_set_rbtree.c
index ec322d818de0..4594e1d88cf9 100644
--- a/net/netfilter/nft_set_rbtree.c
+++ b/net/netfilter/nft_set_rbtree.c
@@ -316,6 +316,7 @@ static int __nft_rbtree_insert(const struct net *net, const struct nft_set *set,
struct nft_rbtree *priv = nft_set_priv(set);
u8 cur_genmask = nft_genmask_cur(net);
u8 genmask = nft_genmask_next(net);
+ u64 tstamp = nft_net_tstamp(net);
int d;
/* Descend the tree to search for an existing element greater than the
@@ -363,7 +364,7 @@ static int __nft_rbtree_insert(const struct net *net, const struct nft_set *set,
/* perform garbage collection to avoid bogus overlap reports
* but skip new elements in this transaction.
*/
- if (nft_set_elem_expired(&rbe->ext) &&
+ if (__nft_set_elem_expired(&rbe->ext, tstamp) &&
nft_set_elem_active(&rbe->ext, cur_genmask)) {
const struct nft_rbtree_elem *removed_end;
@@ -550,6 +551,7 @@ static void *nft_rbtree_deactivate(const struct net *net,
const struct rb_node *parent = priv->root.rb_node;
struct nft_rbtree_elem *rbe, *this = elem->priv;
u8 genmask = nft_genmask_next(net);
+ u64 tstamp = nft_net_tstamp(net);
int d;
while (parent != NULL) {
@@ -570,7 +572,7 @@ static void *nft_rbtree_deactivate(const struct net *net,
nft_rbtree_interval_end(this)) {
parent = parent->rb_right;
continue;
- } else if (nft_set_elem_expired(&rbe->ext)) {
+ } else if (__nft_set_elem_expired(&rbe->ext, tstamp)) {
break;
} else if (!nft_set_elem_active(&rbe->ext, genmask)) {
parent = parent->rb_left;
--
2.43.0
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