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Message-ID: <d32add2c-26ed-4988-990b-3014d7727645@schaufler-ca.com>
Date: Tue, 7 Nov 2023 09:47:22 -0800
From: Casey Schaufler <casey@...aufler-ca.com>
To: Roberto Sassu <roberto.sassu@...weicloud.com>,
viro@...iv.linux.org.uk, brauner@...nel.org,
chuck.lever@...cle.com, jlayton@...nel.org, neilb@...e.de,
kolga@...app.com, Dai.Ngo@...cle.com, tom@...pey.com,
paul@...l-moore.com, jmorris@...ei.org, serge@...lyn.com,
zohar@...ux.ibm.com, dmitry.kasatkin@...il.com,
dhowells@...hat.com, jarkko@...nel.org,
stephen.smalley.work@...il.com, eparis@...isplace.org,
mic@...ikod.net
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-nfs@...r.kernel.org, linux-security-module@...r.kernel.org,
linux-integrity@...r.kernel.org, keyrings@...r.kernel.org,
selinux@...r.kernel.org, Roberto Sassu <roberto.sassu@...wei.com>,
Stefan Berger <stefanb@...ux.ibm.com>,
Casey Schaufler <casey@...aufler-ca.com>
Subject: Re: [PATCH v5 18/23] security: Introduce key_post_create_or_update
hook
On 11/7/2023 5:40 AM, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu@...wei.com>
>
> In preparation for moving IMA and EVM to the LSM infrastructure, introduce
> the key_post_create_or_update hook.
>
> Depending on policy, IMA measures the key content after creation or update,
> so that remote verifiers are aware of the operation.
>
> Other LSMs could similarly take some action after successful key creation
> or update.
>
> The new hook cannot return an error and cannot cause the operation to be
> reverted.
>
> Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
> Reviewed-by: Stefan Berger <stefanb@...ux.ibm.com>
Acked-by: Casey Schaufler <casey@...aufler-ca.com>
> ---
> include/linux/lsm_hook_defs.h | 3 +++
> include/linux/security.h | 11 +++++++++++
> security/keys/key.c | 7 ++++++-
> security/security.c | 19 +++++++++++++++++++
> 4 files changed, 39 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
> index 2bf128f7cbae..ec5d160c32ba 100644
> --- a/include/linux/lsm_hook_defs.h
> +++ b/include/linux/lsm_hook_defs.h
> @@ -403,6 +403,9 @@ LSM_HOOK(void, LSM_RET_VOID, key_free, struct key *key)
> LSM_HOOK(int, 0, key_permission, key_ref_t key_ref, const struct cred *cred,
> enum key_need_perm need_perm)
> LSM_HOOK(int, 0, key_getsecurity, struct key *key, char **buffer)
> +LSM_HOOK(void, LSM_RET_VOID, key_post_create_or_update, struct key *keyring,
> + struct key *key, const void *payload, size_t payload_len,
> + unsigned long flags, bool create)
> #endif /* CONFIG_KEYS */
>
> #ifdef CONFIG_AUDIT
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 7cd7126f6545..1cd84970ab4c 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -1995,6 +1995,9 @@ void security_key_free(struct key *key);
> int security_key_permission(key_ref_t key_ref, const struct cred *cred,
> enum key_need_perm need_perm);
> int security_key_getsecurity(struct key *key, char **_buffer);
> +void security_key_post_create_or_update(struct key *keyring, struct key *key,
> + const void *payload, size_t payload_len,
> + unsigned long flags, bool create);
>
> #else
>
> @@ -2022,6 +2025,14 @@ static inline int security_key_getsecurity(struct key *key, char **_buffer)
> return 0;
> }
>
> +static inline void security_key_post_create_or_update(struct key *keyring,
> + struct key *key,
> + const void *payload,
> + size_t payload_len,
> + unsigned long flags,
> + bool create)
> +{ }
> +
> #endif
> #endif /* CONFIG_KEYS */
>
> diff --git a/security/keys/key.c b/security/keys/key.c
> index 0260a1902922..f75fe66c2f03 100644
> --- a/security/keys/key.c
> +++ b/security/keys/key.c
> @@ -935,6 +935,8 @@ static key_ref_t __key_create_or_update(key_ref_t keyring_ref,
> goto error_link_end;
> }
>
> + security_key_post_create_or_update(keyring, key, payload, plen, flags,
> + true);
> ima_post_key_create_or_update(keyring, key, payload, plen,
> flags, true);
>
> @@ -968,10 +970,13 @@ static key_ref_t __key_create_or_update(key_ref_t keyring_ref,
>
> key_ref = __key_update(key_ref, &prep);
>
> - if (!IS_ERR(key_ref))
> + if (!IS_ERR(key_ref)) {
> + security_key_post_create_or_update(keyring, key, payload, plen,
> + flags, false);
> ima_post_key_create_or_update(keyring, key,
> payload, plen,
> flags, false);
> + }
>
> goto error_free_prep;
> }
> diff --git a/security/security.c b/security/security.c
> index 6eb7c9cff1e5..859189722ab8 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -5406,6 +5406,25 @@ int security_key_getsecurity(struct key *key, char **buffer)
> *buffer = NULL;
> return call_int_hook(key_getsecurity, 0, key, buffer);
> }
> +
> +/**
> + * security_key_post_create_or_update() - Notification of key create or update
> + * @keyring: keyring to which the key is linked to
> + * @key: created or updated key
> + * @payload: data used to instantiate or update the key
> + * @payload_len: length of payload
> + * @flags: key flags
> + * @create: flag indicating whether the key was created or updated
> + *
> + * Notify the caller of a key creation or update.
> + */
> +void security_key_post_create_or_update(struct key *keyring, struct key *key,
> + const void *payload, size_t payload_len,
> + unsigned long flags, bool create)
> +{
> + call_void_hook(key_post_create_or_update, keyring, key, payload,
> + payload_len, flags, create);
> +}
> #endif /* CONFIG_KEYS */
>
> #ifdef CONFIG_AUDIT
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