| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <686aaac58f744_3ad0f32943d@willemb.c.googlers.com.notmuch>
Date: Sun, 06 Jul 2025 12:56:37 -0400
From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
To: Daniel Zahka <daniel.zahka@...il.com>,
Donald Hunter <donald.hunter@...il.com>,
Jakub Kicinski <kuba@...nel.org>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Paolo Abeni <pabeni@...hat.com>,
Simon Horman <horms@...nel.org>,
Jonathan Corbet <corbet@....net>,
Andrew Lunn <andrew+netdev@...n.ch>
Cc: Saeed Mahameed <saeedm@...dia.com>,
Leon Romanovsky <leon@...nel.org>,
Tariq Toukan <tariqt@...dia.com>,
Boris Pismenny <borisp@...dia.com>,
Kuniyuki Iwashima <kuniyu@...gle.com>,
Willem de Bruijn <willemb@...gle.com>,
David Ahern <dsahern@...nel.org>,
Neal Cardwell <ncardwell@...gle.com>,
Patrisious Haddad <phaddad@...dia.com>,
Raed Salem <raeds@...dia.com>,
Jianbo Liu <jianbol@...dia.com>,
Dragos Tatulea <dtatulea@...dia.com>,
Rahul Rameshbabu <rrameshbabu@...dia.com>,
Stanislav Fomichev <sdf@...ichev.me>,
Toke Høiland-Jørgensen <toke@...hat.com>,
Alexander Lobakin <aleksander.lobakin@...el.com>,
Jacob Keller <jacob.e.keller@...el.com>,
netdev@...r.kernel.org
Subject: Re: [PATCH v3 10/19] psp: track generations of device key
Daniel Zahka wrote:
> From: Jakub Kicinski <kuba@...nel.org>
>
> There is a (somewhat theoretical in absence of multi-host support)
> possibility that another entity will rotate the key and we won't
> know. This may lead to accepting packets with matching SPI but
> which used different crypto keys than we expected.
The device would not have decrypted those? As it only has two keys,
one for each MSB of the SPI.
Except for a narrow window during rotation, where a key for generation
N is decrypted and queued to the host, then a rotation happens, so that
the host updates its valid keys to { N+1, N+2 }. These will now get
dropped. That is not strictly necessary.
> Maintain and
> compare "key generation" per PSP spec.
Where does the spec state this?
I know this generation bit is present in the Google PSP
implementation, I'm just right now drawing a blank as to its exact
purpose -- and whether the above explanation matches that.
> Since we're tracking "key generations" more explicitly now,
> maintain different lists for associations from different generations.
> This way we can catch stale associations (the user space should
> listen to rotation notifications and change the keys).
>
> Drivers can "opt out" of generation tracking by setting
> the generation value to 0.
>
> Signed-off-by: Jakub Kicinski <kuba@...nel.org>
> Signed-off-by: Daniel Zahka <daniel.zahka@...il.com>
> ---
>
> Notes:
> v1:
> - https://lore.kernel.org/netdev/20240510030435.120935-9-kuba@kernel.org/
>
> include/net/psp/types.h | 10 ++++++++++
> net/psp/psp.h | 1 +
> net/psp/psp_main.c | 6 +++++-
> net/psp/psp_nl.c | 10 ++++++++++
> net/psp/psp_sock.c | 16 ++++++++++++++++
> 5 files changed, 42 insertions(+), 1 deletion(-)
>
> diff --git a/include/net/psp/types.h b/include/net/psp/types.h
> index 5b0c2474a042..383a1afab46d 100644
> --- a/include/net/psp/types.h
> +++ b/include/net/psp/types.h
> @@ -50,8 +50,12 @@ struct psp_dev_config {
> * @lock: instance lock, protects all fields
> * @refcnt: reference count for the instance
> * @id: instance id
> + * @generation: current generation of the device key
> * @config: current device configuration
> * @active_assocs: list of registered associations
> + * @prev_assocs: associations which use old (but still usable)
> + * device key
> + * @stale_assocs: associations which use a rotated out key
> *
> * @rcu: RCU head for freeing the structure
> */
> @@ -67,13 +71,19 @@ struct psp_dev {
>
> u32 id;
>
> + u8 generation;
> +
> struct psp_dev_config config;
>
> struct list_head active_assocs;
> + struct list_head prev_assocs;
> + struct list_head stale_assocs;
>
> struct rcu_head rcu;
> };
>
> +#define PSP_GEN_VALID_MASK 0x7f
> +
> /**
> * struct psp_dev_caps - PSP device capabilities
> */
> diff --git a/net/psp/psp.h b/net/psp/psp.h
> index b4092936bc64..a511ec85e1c7 100644
> --- a/net/psp/psp.h
> +++ b/net/psp/psp.h
> @@ -27,6 +27,7 @@ int psp_sock_assoc_set_rx(struct sock *sk, struct psp_assoc *pas,
> int psp_sock_assoc_set_tx(struct sock *sk, struct psp_dev *psd,
> u32 version, struct psp_key_parsed *key,
> struct netlink_ext_ack *extack);
> +void psp_assocs_key_rotated(struct psp_dev *psd);
>
> static inline void psp_dev_get(struct psp_dev *psd)
> {
> diff --git a/net/psp/psp_main.c b/net/psp/psp_main.c
> index bf1c704a1a40..99facb158abb 100644
> --- a/net/psp/psp_main.c
> +++ b/net/psp/psp_main.c
> @@ -72,6 +72,8 @@ psp_dev_create(struct net_device *netdev,
>
> mutex_init(&psd->lock);
> INIT_LIST_HEAD(&psd->active_assocs);
> + INIT_LIST_HEAD(&psd->prev_assocs);
> + INIT_LIST_HEAD(&psd->stale_assocs);
> refcount_set(&psd->refcnt, 1);
>
> mutex_lock(&psp_devs_lock);
> @@ -120,7 +122,9 @@ void psp_dev_unregister(struct psp_dev *psd)
> xa_store(&psp_devs, psd->id, NULL, GFP_KERNEL);
> mutex_unlock(&psp_devs_lock);
>
> - list_for_each_entry_safe(pas, next, &psd->active_assocs, assocs_list)
> + list_splice_init(&psd->active_assocs, &psd->prev_assocs);
> + list_splice_init(&psd->prev_assocs, &psd->stale_assocs);
> + list_for_each_entry_safe(pas, next, &psd->stale_assocs, assocs_list)
> psp_dev_tx_key_del(psd, pas);
>
> rcu_assign_pointer(psd->main_netdev->psp_dev, NULL);
> diff --git a/net/psp/psp_nl.c b/net/psp/psp_nl.c
> index 58508e642185..7b8a1d390cde 100644
> --- a/net/psp/psp_nl.c
> +++ b/net/psp/psp_nl.c
> @@ -230,6 +230,7 @@ int psp_nl_key_rotate_doit(struct sk_buff *skb, struct genl_info *info)
> struct psp_dev *psd = info->user_ptr[0];
> struct genl_info ntf_info;
> struct sk_buff *ntf, *rsp;
> + u8 prev_gen;
> int err;
>
> rsp = psp_nl_reply_new(info);
> @@ -249,10 +250,19 @@ int psp_nl_key_rotate_doit(struct sk_buff *skb, struct genl_info *info)
> goto err_free_ntf;
> }
>
> + /* suggest the next gen number, driver can override */
> + prev_gen = psd->generation;
> + psd->generation = (prev_gen + 1) & PSP_GEN_VALID_MASK;
> +
> err = psd->ops->key_rotate(psd, info->extack);
> if (err)
> goto err_free_ntf;
>
> + WARN_ON_ONCE((psd->generation && psd->generation == prev_gen) ||
> + psd->generation & ~PSP_GEN_VALID_MASK);
> +
> + psp_assocs_key_rotated(psd);
> +
> nlmsg_end(ntf, (struct nlmsghdr *)ntf->data);
> genlmsg_multicast_netns(&psp_nl_family, dev_net(psd->main_netdev), ntf,
> 0, PSP_NLGRP_USE, GFP_KERNEL);
> diff --git a/net/psp/psp_sock.c b/net/psp/psp_sock.c
> index f97441935d12..8b5cb31c2836 100644
> --- a/net/psp/psp_sock.c
> +++ b/net/psp/psp_sock.c
> @@ -60,6 +60,7 @@ struct psp_assoc *psp_assoc_create(struct psp_dev *psd)
>
> pas->psd = psd;
> pas->dev_id = psd->id;
> + pas->generation = psd->generation;
> psp_dev_get(psd);
> refcount_set(&pas->refcnt, 1);
>
> @@ -243,6 +244,21 @@ int psp_sock_assoc_set_tx(struct sock *sk, struct psp_dev *psd,
> return err;
> }
>
> +void psp_assocs_key_rotated(struct psp_dev *psd)
> +{
> + struct psp_assoc *pas, *next;
> +
> + /* Mark the stale associations as invalid, they will no longer
> + * be able to Rx any traffic.
> + */
> + list_for_each_entry_safe(pas, next, &psd->prev_assocs, assocs_list)
> + pas->generation |= ~PSP_GEN_VALID_MASK;
> + list_splice_init(&psd->prev_assocs, &psd->stale_assocs);
> + list_splice_init(&psd->active_assocs, &psd->prev_assocs);
> +
> + /* TODO: we should inform the sockets that got shut down */
> +}
> +
> void psp_twsk_init(struct inet_timewait_sock *tw, struct sock *sk)
> {
> struct psp_assoc *pas = psp_sk_assoc(sk);
> --
> 2.47.1
>
Powered by blists - more mailing lists