Re: [PATCH v6 05/12] integrity: Introduce integrity_keyring_from_id()

[Mimi Zohar <zohar@linux.vnet.ibm.com>]

On Fri, 2018-03-16 at 17:38 -0300, Thiago Jung Bauermann wrote:
> IMA will need to obtain the keyring used to verify file signatures so that
> it can verify the module-style signature appended to files.
> 
> Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

> ---
>  security/integrity/digsig.c    | 28 +++++++++++++++++++++-------
>  security/integrity/integrity.h |  6 ++++++
>  2 files changed, 27 insertions(+), 7 deletions(-)
> 
> diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
> index 6f9e4ce568cd..e641a67b9fc7 100644
> --- a/security/integrity/digsig.c
> +++ b/security/integrity/digsig.c
> @@ -48,11 +48,10 @@ static bool init_keyring __initdata;
>  #define restrict_link_to_ima restrict_link_by_builtin_trusted
>  #endif
> 
> -int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
> -			    const char *digest, int digestlen)
> +struct key *integrity_keyring_from_id(const unsigned int id)
>  {
> -	if (id >= INTEGRITY_KEYRING_MAX || siglen < 2)
> -		return -EINVAL;
> +	if (id >= INTEGRITY_KEYRING_MAX)
> +		return ERR_PTR(-EINVAL);
> 
>  	if (!keyring[id]) {
>  		keyring[id] > @@ -61,17 +60,32 @@ int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
>  			int err = PTR_ERR(keyring[id]);
>  			pr_err("no %s keyring: %d\n", keyring_name[id], err);
>  			keyring[id] = NULL;
> -			return err;
> +			return ERR_PTR(err);
>  		}
>  	}
> 
> +	return keyring[id];
> +}
> +
> +int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
> +			    const char *digest, int digestlen)
> +{
> +	struct key *keyring;
> +
> +	if (siglen < 2)
> +		return -EINVAL;
> +
> +	keyring = integrity_keyring_from_id(id);
> +	if (IS_ERR(keyring))
> +		return PTR_ERR(keyring);
> +
>  	switch (sig[1]) {
>  	case 1:
>  		/* v1 API expect signature without xattr type */
> -		return digsig_verify(keyring[id], sig + 1, siglen - 1,
> +		return digsig_verify(keyring, sig + 1, siglen - 1,
>  				     digest, digestlen);
>  	case 2:
> -		return asymmetric_verify(keyring[id], sig, siglen,
> +		return asymmetric_verify(keyring, sig, siglen,
>  					 digest, digestlen);
>  	}
> 
> diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
> index 79799a0d9195..2d245f44ca26 100644
> --- a/security/integrity/integrity.h
> +++ b/security/integrity/integrity.h
> @@ -150,6 +150,7 @@ int integrity_kernel_read(struct file *file, loff_t offset,
> 
>  #ifdef CONFIG_INTEGRITY_SIGNATURE
> 
> +struct key *integrity_keyring_from_id(const unsigned int id);
>  int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
>  			    const char *digest, int digestlen);
> 
> @@ -157,6 +158,11 @@ int __init integrity_init_keyring(const unsigned int id);
>  int __init integrity_load_x509(const unsigned int id, const char *path);
>  #else
> 
> +static inline struct key *integrity_keyring_from_id(const unsigned int id)
> +{
> +	return ERR_PTR(-EINVAL);
> +}
> +
>  static inline int integrity_digsig_verify(const unsigned int id,
>  					  const char *sig, int siglen,
>  					  const char *digest, int digestlen)
>