linux-kernel - Re: [PATCH v6 3/3] KEYS: Call the IMA hook to measure keys

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Date:   Wed, 13 Nov 2019 15:09:24 -0500
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>,
        dhowells@...hat.com, matthewgarrett@...gle.com, sashal@...nel.org,
        jamorris@...ux.microsoft.com, linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org, keyrings@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 3/3] KEYS: Call the IMA hook to measure keys

On Wed, 2019-11-13 at 10:46 -0800, Lakshmi Ramasubramanian wrote:
> Call the IMA hook from key_create_or_update function to measure
> the key when a new key is created or an existing key is updated.
> 
> This patch adds the call to the IMA hook from key_create_or_update
> function to measure the key on key create or update.
> 
> Signed-off-by: Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
> ---
>  include/linux/ima.h | 13 +++++++++++++
>  security/keys/key.c |  9 +++++++++
>  2 files changed, 22 insertions(+)
> 
> diff --git a/include/linux/ima.h b/include/linux/ima.h
> index 6d904754d858..ec5afe319ab7 100644
> --- a/include/linux/ima.h
> +++ b/include/linux/ima.h
> @@ -25,6 +25,12 @@ extern int ima_post_read_file(struct file *file, void *buf, loff_t size,
>  extern void ima_post_path_mknod(struct dentry *dentry);
>  extern void ima_kexec_cmdline(const void *buf, int size);
>  
> +#ifdef CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS
> +extern void ima_post_key_create_or_update(struct key *keyring,
> +					  struct key *key,
> +					  unsigned long flags, bool create);
> +#endif
> +
>  #ifdef CONFIG_IMA_KEXEC
>  extern void ima_add_kexec_buffer(struct kimage *image);
>  #endif
> @@ -101,6 +107,13 @@ static inline void ima_add_kexec_buffer(struct kimage *image)
>  {}
>  #endif
>  
> +#ifndef CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS
> +static inline void ima_post_key_create_or_update(struct key *keyring,
> +						 struct key *key,
> +						 unsigned long flags,
> +						 bool create) {}
> +#endif
> +
>  #ifdef CONFIG_IMA_APPRAISE
>  extern bool is_ima_appraise_enabled(void);
>  extern void ima_inode_post_setattr(struct dentry *dentry);
> diff --git a/security/keys/key.c b/security/keys/key.c
> index 764f4c57913e..9782d4d046fd 100644
> --- a/security/keys/key.c
> +++ b/security/keys/key.c
> @@ -13,6 +13,7 @@
>  #include <linux/security.h>
>  #include <linux/workqueue.h>
>  #include <linux/random.h>
> +#include <linux/ima.h>
>  #include <linux/err.h>
>  #include "internal.h"
>  
> @@ -936,6 +937,9 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref,
>  		goto error_link_end;
>  	}
>  
> +	/* let the ima module know about the created key. */

This comment and the one below doesn't provide any additional
information.  Please remove them.

> +	ima_post_key_create_or_update(keyring, key, flags, true);
> +
>  	key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
>  
>  error_link_end:
> @@ -965,6 +969,11 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref,
>  	}
>  
>  	key_ref = __key_update(key_ref, &prep);
> +
> +	/* let the ima module know about the updated key. */
> +	if (!IS_ERR(key_ref))
> +		ima_post_key_create_or_update(keyring, key, flags, false);
> +
>  	goto error_free_prep;
>  }
>  EXPORT_SYMBOL(key_create_or_update);