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Donenfeld" , wireguard@lists.zx2c4.com, netdev@vger.kernel.org Cc: Andrew Lunn , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-kernel@vger.kernel.org, Alexander Ildiyarov , stable@vger.kernel.org Subject: [PATCH net 1/2] wireguard: account peer and allowedips allocations to memcg Date: Thu, 5 Nov 2026 17:10:05 +0300 Message-ID: <20261105141006.95083-2-alex@badcode.im> In-Reply-To: <20261105141006.95083-1-alex@badcode.im> References: <20261105141006.95083-1-alex@badcode.im> X-Mailing-List: netdev@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spamd-Bar: - Peers, allowed IP trie nodes, the per-peer dst_cache and the per-device hashtables are all allocated in the context of the process that configures the device over netlink, but none of these allocations are charged to that process's memory cgroup: the wg_peer and allowedips_node caches are created without SLAB_ACCOUNT, and the hashtables and dst_cache use plain GFP_KERNEL. The amount of memory is bounded only by MAX_PEERS_PER_DEVICE (2^20) per device, with no limit on the number of devices or on the number of allowed IPs per peer. Since WG_CMD_SET_DEVICE uses GENL_UNS_ADMIN_PERM, any user who can create a user and network namespace can do this, and thereby escape the memory limits of the cgroup it runs in. For example, a process in a cgroup with memory.max=64M that adds 100000 peers with 20 /128 allowed IPs each grows Slab by ~790 MiB, yet the cgroup's memory.current stays below 1 MiB and its memory limit is never hit. Fix this by creating the two caches with SLAB_ACCOUNT and using GFP_KERNEL_ACCOUNT for the hashtables and the dst_cache. The keypair allocations are left alone, as they happen from the handshake worker and are bounded to three per peer. Fixes: e7096c131e51 ("net: WireGuard secure network tunnel") Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: Alexander Ildiyarov --- drivers/net/wireguard/allowedips.c | 2 +- drivers/net/wireguard/peer.c | 4 ++-- drivers/net/wireguard/peerlookup.c | 4 ++-- 3 files changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/net/wireguard/allowedips.c b/drivers/net/wireguard/allowedips.c index 5ece9acad64d..2f2b8a94c8a7 100644 --- a/drivers/net/wireguard/allowedips.c +++ b/drivers/net/wireguard/allowedips.c @@ -411,7 +411,7 @@ struct wg_peer *wg_allowedips_lookup_src(struct allowedips *table, int __init wg_allowedips_slab_init(void) { - node_cache = KMEM_CACHE(allowedips_node, 0); + node_cache = KMEM_CACHE(allowedips_node, SLAB_ACCOUNT); return node_cache ? 0 : -ENOMEM; } diff --git a/drivers/net/wireguard/peer.c b/drivers/net/wireguard/peer.c index 1cb502a932e0..05b80521c706 100644 --- a/drivers/net/wireguard/peer.c +++ b/drivers/net/wireguard/peer.c @@ -33,7 +33,7 @@ struct wg_peer *wg_peer_create(struct wg_device *wg, peer = kmem_cache_zalloc(peer_cache, GFP_KERNEL); if (unlikely(!peer)) return ERR_PTR(ret); - if (unlikely(dst_cache_init(&peer->endpoint_cache, GFP_KERNEL))) + if (unlikely(dst_cache_init(&peer->endpoint_cache, GFP_KERNEL_ACCOUNT))) goto err; peer->device = wg; @@ -229,7 +229,7 @@ void wg_peer_put(struct wg_peer *peer) int __init wg_peer_init(void) { - peer_cache = KMEM_CACHE(wg_peer, 0); + peer_cache = KMEM_CACHE(wg_peer, SLAB_ACCOUNT); return peer_cache ? 0 : -ENOMEM; } diff --git a/drivers/net/wireguard/peerlookup.c b/drivers/net/wireguard/peerlookup.c index 99651a86ac95..f333e906014a 100644 --- a/drivers/net/wireguard/peerlookup.c +++ b/drivers/net/wireguard/peerlookup.c @@ -21,7 +21,7 @@ static struct hlist_head *pubkey_bucket(struct pubkey_hashtable *table, struct pubkey_hashtable *wg_pubkey_hashtable_alloc(void) { - struct pubkey_hashtable *table = kvmalloc_obj(*table); + struct pubkey_hashtable *table = kvmalloc_obj(*table, GFP_KERNEL_ACCOUNT); if (!table) return NULL; @@ -82,7 +82,7 @@ static struct hlist_head *index_bucket(struct index_hashtable *table, struct index_hashtable *wg_index_hashtable_alloc(void) { - struct index_hashtable *table = kvmalloc_obj(*table); + struct index_hashtable *table = kvmalloc_obj(*table, GFP_KERNEL_ACCOUNT); if (!table) return NULL; -- 2.43.0