Re: [added to the 3.18 stable tree] KEYS: fix "ca_keys=" partial key matching

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

Hi Sasha,

Thanks!  The first two patches listed below aren't "necessary", but with
them the rest of the bug fixes apply cleanly.

# ima: skip measurement of cgroupfs files and update documentation
git cherry-pick 6438de9 -x

# ima: cleanup ima_init_policy() a little
git cherry-pick 5577857 -x

# ima: do not measure or appraise the NSFS filesystem  (back  to and
including 3.19)
git cherry-pick cd025f7 -x

# evm: labeling pseudo filesystems exception (back to and including
3.17,  3.14)
git cherry-pick 5101a18 -x

# KEYS: fix "ca_keys=" partial key matching  (back to and including
3.18)
git cherry-pick f2b3dee -x

# ima: fix ima_show_template_data_ascii()  (back to and including 3.13)
git cherry-pick 45b2613 -x

# ima: add support for new "euid" policy condition
git cherry-pick 139069e -x

# ima: extend "mask" policy matching support
git cherry-pick 4351c29 -x

# ima: update builtin policies
git cherry-pick 24fd03c -x

Thanks,

Mimi


On Fri, 2015-07-03 at 23:01 -0400, Sasha Levin wrote:
> From: Mimi Zohar <zohar@linux.vnet.ibm.com>
> 
> This patch has been added to the 3.18 stable tree. If you have any
> objections, please let us know.
> 
> ===============
> 
> [ Upstream commit f2b3dee484f9cee967a54ef05a66866282337519 ]
> 
> The call to asymmetric_key_hex_to_key_id() from ca_keys_setup()
> silently fails with -ENOMEM.  Instead of dynamically allocating
> memory from a __setup function, this patch defines a variable
> and calls __asymmetric_key_hex_to_key_id(), a new helper function,
> directly.
> 
> This bug was introduced by 'commit 46963b774d44 ("KEYS: Overhaul
> key identification when searching for asymmetric keys")'.
> 
> Changelog:
> - for clarification, rename hexlen to asciihexlen in
>   asymmetric_key_hex_to_key_id()
> - add size argument to __asymmetric_key_hex_to_key_id() - David Howells
> - inline __asymmetric_key_hex_to_key_id() - David Howells
> - remove duplicate strlen() calls
> 
> Acked-by: David Howells <dhowells@redhat.com>
> Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
> Cc: stable@vger.kernel.org # 3.18
> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
> ---
>  crypto/asymmetric_keys/asymmetric_keys.h |  3 +++
>  crypto/asymmetric_keys/asymmetric_type.c | 20 ++++++++++++++------
>  crypto/asymmetric_keys/x509_public_key.c | 23 ++++++++++++++++++-----
>  3 files changed, 35 insertions(+), 11 deletions(-)
> 
> diff --git a/crypto/asymmetric_keys/asymmetric_keys.h b/crypto/asymmetric_keys/asymmetric_keys.h
> index f973308..3f5b537 100644
> --- a/crypto/asymmetric_keys/asymmetric_keys.h
> +++ b/crypto/asymmetric_keys/asymmetric_keys.h
> @@ -11,6 +11,9 @@
> 
>  extern struct asymmetric_key_id *asymmetric_key_hex_to_key_id(const char *id);
> 
> +extern int __asymmetric_key_hex_to_key_id(const char *id,
> +					  struct asymmetric_key_id *match_id,
> +					  size_t hexlen);
>  static inline
>  const struct asymmetric_key_ids *asymmetric_key_ids(const struct key *key)
>  {
> diff --git a/crypto/asymmetric_keys/asymmetric_type.c b/crypto/asymmetric_keys/asymmetric_type.c
> index bcbbbd7..b0e4ed2 100644
> --- a/crypto/asymmetric_keys/asymmetric_type.c
> +++ b/crypto/asymmetric_keys/asymmetric_type.c
> @@ -104,6 +104,15 @@ static bool asymmetric_match_key_ids(
>  	return false;
>  }
> 
> +/* helper function can be called directly with pre-allocated memory */
> +inline int __asymmetric_key_hex_to_key_id(const char *id,
> +				   struct asymmetric_key_id *match_id,
> +				   size_t hexlen)
> +{
> +	match_id->len = hexlen;
> +	return hex2bin(match_id->data, id, hexlen);
> +}
> +
>  /**
>   * asymmetric_key_hex_to_key_id - Convert a hex string into a key ID.
>   * @id: The ID as a hex string.
> @@ -111,21 +120,20 @@ static bool asymmetric_match_key_ids(
>  struct asymmetric_key_id *asymmetric_key_hex_to_key_id(const char *id)
>  {
>  	struct asymmetric_key_id *match_id;
> -	size_t hexlen;
> +	size_t asciihexlen;
>  	int ret;
> 
>  	if (!*id)
>  		return ERR_PTR(-EINVAL);
> -	hexlen = strlen(id);
> -	if (hexlen & 1)
> +	asciihexlen = strlen(id);
> +	if (asciihexlen & 1)
>  		return ERR_PTR(-EINVAL);
> 
> -	match_id = kmalloc(sizeof(struct asymmetric_key_id) + hexlen / 2,
> +	match_id = kmalloc(sizeof(struct asymmetric_key_id) + asciihexlen / 2,
>  			   GFP_KERNEL);
>  	if (!match_id)
>  		return ERR_PTR(-ENOMEM);
> -	match_id->len = hexlen / 2;
> -	ret = hex2bin(match_id->data, id, hexlen / 2);
> +	ret = __asymmetric_key_hex_to_key_id(id, match_id, asciihexlen / 2);
>  	if (ret < 0) {
>  		kfree(match_id);
>  		return ERR_PTR(-EINVAL);
> diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
> index a6c4203..24f17e6 100644
> --- a/crypto/asymmetric_keys/x509_public_key.c
> +++ b/crypto/asymmetric_keys/x509_public_key.c
> @@ -28,17 +28,30 @@ static bool use_builtin_keys;
>  static struct asymmetric_key_id *ca_keyid;
> 
>  #ifndef MODULE
> +static struct {
> +	struct asymmetric_key_id id;
> +	unsigned char data[10];
> +} cakey;
> +
>  static int __init ca_keys_setup(char *str)
>  {
>  	if (!str)		/* default system keyring */
>  		return 1;
> 
>  	if (strncmp(str, "id:", 3) == 0) {
> -		struct asymmetric_key_id *p;
> -		p = asymmetric_key_hex_to_key_id(str + 3);
> -		if (p == ERR_PTR(-EINVAL))
> -			pr_err("Unparsable hex string in ca_keys\n");
> -		else if (!IS_ERR(p))
> +		struct asymmetric_key_id *p = &cakey.id;
> +		size_t hexlen = (strlen(str) - 3) / 2;
> +		int ret;
> +
> +		if (hexlen == 0 || hexlen > sizeof(cakey.data)) {
> +			pr_err("Missing or invalid ca_keys id\n");
> +			return 1;
> +		}
> +
> +		ret = __asymmetric_key_hex_to_key_id(str + 3, p, hexlen);
> +		if (ret < 0)
> +			pr_err("Unparsable ca_keys id hex string\n");
> +		else
>  			ca_keyid = p;	/* owner key 'id:xxxxxx' */
>  	} else if (strcmp(str, "builtin") == 0) {
>  		use_builtin_keys = true;