Re: [ima-evm-utils PATCH v2 03/13] Update library function definitions to include a "public_keys" parameter

[Stefan Berger <stefanb@linux.ibm.com>]

On 12/6/23 14:27, Mimi Zohar wrote:
> Instead of relying on a global static "public_keys" variable, which is
> not concurrency-safe, update static library function definitions to
> include it as a parameter, define new library functions with it as
> a parameter, and deprecate existing functions.
> 
> Define imaevm_init_public_keys(), imaevm_verify_hash(), and
> ima_verify_signature2() functions. Update static function definitions
> to include "public_keys".
> 
> To avoid library incompatibility, make the existing functions -
> init_public_keys(), verify_hash(), ima_verify_signature() - wrappers
> for the new function versions.
> 
> Deprecate init_public_keys(), verify_hash(), ima_verify_signature()
> functions.
> 
> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
> ---
>   src/imaevm.h    |  4 +++
>   src/libimaevm.c | 85 ++++++++++++++++++++++++++++++++++++-------------
>   2 files changed, 67 insertions(+), 22 deletions(-)
> 
> diff --git a/src/imaevm.h b/src/imaevm.h
> index 470e8376f2fb..b29a4745fc77 100644
> --- a/src/imaevm.h
> +++ b/src/imaevm.h
> @@ -249,8 +249,12 @@ uint32_t imaevm_read_keyid(const char *certfile);
>   int sign_hash(const char *algo, const unsigned char *hash, int size, const char *keyfile, const char *keypass, unsigned char *sig);
>   int verify_hash(const char *file, const unsigned char *hash, int size, unsigned char *sig, int siglen);
>   int ima_verify_signature(const char *file, unsigned char *sig, int siglen, unsigned char *digest, int digestlen);

Forward-declare struct public_key_entry here:
struct public_key_entry;

> +int ima_verify_signature2(void *public_keys, const char *file,

And use it instead of void * here. For the user it's going to be an 
opaque type but better then a void*.

> +			  unsigned char *sig, int siglen,
> +			  unsigned char *digest, int digestlen);
>   void imaevm_free_public_keys(void *public_keys);
>   void init_public_keys(const char *keyfiles);
> +int imaevm_init_public_keys(const char *keyfiles, void **public_keys);
>   int imaevm_hash_algo_from_sig(unsigned char *sig);
>   const char *imaevm_hash_algo_by_id(int algo);
>   int calc_hash_sigv3(enum evm_ima_xattr_type type, const char *algo, const unsigned char *in_hash, unsigned char *out_hash);
> diff --git a/src/libimaevm.c b/src/libimaevm.c
> index 534468fe99ca..6fecb2ffd139 100644
> --- a/src/libimaevm.c
> +++ b/src/libimaevm.c
> @@ -372,12 +372,13 @@ struct public_key_entry {
>   };
>   static struct public_key_entry *g_public_keys = NULL;
>   
> -static EVP_PKEY *find_keyid(uint32_t keyid)
> +static EVP_PKEY *find_keyid(struct public_key_entry *public_keys,
> +			    uint32_t keyid)
>   {
> -	struct public_key_entry *entry, *tail = g_public_keys;
> +	struct public_key_entry *entry, *tail = public_keys;
>   	int i = 1;
>   
> -	for (entry = g_public_keys; entry; entry = entry->next) {
> +	for (entry = public_keys; entry; entry = entry->next) {
>   		if (entry->keyid == keyid)
>   			return entry->key;
>   		i++;
> @@ -394,7 +395,7 @@ static EVP_PKEY *find_keyid(uint32_t keyid)
>   	if (tail)
>   		tail->next = entry;
>   	else
> -		g_public_keys = entry;
> +		public_keys = (void *)entry;
>   	log_err("key %d: %x (unknown keyid)\n", i, __be32_to_cpup(&keyid));
>   	return 0;
>   }
> @@ -412,7 +413,7 @@ void imaevm_free_public_keys(void *public_keys)
>   	}
>   }
>   
> -void init_public_keys(const char *keyfiles)
> +int imaevm_init_public_keys(const char *keyfiles, void **public_keys)
>   {
>   	struct public_key_entry *entry;
>   	char *tmp_keyfiles, *keyfiles_free;
> @@ -420,6 +421,11 @@ void init_public_keys(const char *keyfiles)
>   	int err = 0;
>   	int i = 1;
>   
> +	if (!public_keys)
> +		return -EINVAL;
> +
> +	*public_keys = NULL;
> +
>   	tmp_keyfiles = strdup(keyfiles);
>   	keyfiles_free = tmp_keyfiles;
>   
> @@ -444,12 +450,19 @@ void init_public_keys(const char *keyfiles)
>   		calc_keyid_v2(&entry->keyid, entry->name, entry->key);
>   		sprintf(entry->name, "%x", __be32_to_cpup(&entry->keyid));
>   		log_info("key %d: %s %s\n", i++, entry->name, keyfile);
> -		entry->next = g_public_keys;
> -		g_public_keys = entry;
> +		entry->next = (struct public_key_entry *)*public_keys;
> +		*public_keys = (void *)entry;
>   	}
> +
>   	free(keyfiles_free);
>   	if (err < 0)
> -		imaevm_free_public_keys(g_public_keys);
> +		imaevm_free_public_keys(public_keys);
> +	return err;
> +}
> +
> +__attribute__((deprecated)) void init_public_keys(const char *keyfiles)

The attribute should go into the header file.



> +{
> +	imaevm_init_public_keys(keyfiles, (void **)&g_public_keys);
>   }
>   
>   /*
> @@ -466,7 +479,8 @@ void init_public_keys(const char *keyfiles)
>    *
>    * (Note: signature_v2_hdr struct does not contain the 'type'.)
>    */
> -static int verify_hash_common(const char *file, const unsigned char *hash,
> +static int verify_hash_common(struct public_key_entry *public_keys,
> +			      const char *file, const unsigned char *hash,
>   			      int size, unsigned char *sig, int siglen)
>   {
>   	int ret = -1;
> @@ -481,7 +495,7 @@ static int verify_hash_common(const char *file, const unsigned char *hash,
>   		log_dump(hash, size);
>   	}
>   
> -	pkey = find_keyid(hdr->keyid);
> +	pkey = find_keyid(public_keys, hdr->keyid);
>   	if (!pkey) {
>   		uint32_t keyid = hdr->keyid;
>   
> @@ -543,11 +557,13 @@ err:
>    *
>    * Return: 0 verification good, 1 verification bad, -1 error.
>    */
> -static int verify_hash_v2(const char *file, const unsigned char *hash,
> +static int verify_hash_v2(struct public_key_entry *public_keys,
> +			  const char *file, const unsigned char *hash,
>   			  int size, unsigned char *sig, int siglen)
>   {
>   	/* note: signature_v2_hdr does not contain 'type', use sig + 1 */
> -	return verify_hash_common(file, hash, size, sig + 1, siglen - 1);
> +	return verify_hash_common(public_keys, file, hash, size,
> +				  sig + 1, siglen - 1);
>   }
>   
>   /*
> @@ -556,7 +572,8 @@ static int verify_hash_v2(const char *file, const unsigned char *hash,
>    *
>    * Return: 0 verification good, 1 verification bad, -1 error.
>    */
> -static int verify_hash_v3(const char *file, const unsigned char *hash,
> +static int verify_hash_v3(struct public_key_entry *public_keys,
> +			  const char *file, const unsigned char *hash,
>   			  int size, unsigned char *sig, int siglen)
>   {
>   	unsigned char sigv3_hash[MAX_DIGEST_SIZE];
> @@ -567,7 +584,8 @@ static int verify_hash_v3(const char *file, const unsigned char *hash,
>   		return ret;
>   
>   	/* note: signature_v2_hdr does not contain 'type', use sig + 1 */
> -	return verify_hash_common(file, sigv3_hash, size, sig + 1, siglen - 1);
> +	return verify_hash_common(public_keys, file, sigv3_hash, size,
> +				  sig + 1, siglen - 1);
>   }
>   
>   #define HASH_MAX_DIGESTSIZE 64	/* kernel HASH_MAX_DIGESTSIZE is 64 bytes */
> @@ -710,8 +728,9 @@ int imaevm_hash_algo_from_sig(unsigned char *sig)
>   		return -1;
>   }
>   
> -int verify_hash(const char *file, const unsigned char *hash, int size,
> -		unsigned char *sig, int siglen)
> +int imaevm_verify_hash(void *public_keys, const char *file,
> +		       const unsigned char *hash, int size,
> +		       unsigned char *sig, int siglen)
>   {
>   	/* Get signature type from sig header */
>   	if (sig[1] == DIGSIG_VERSION_1) {
> @@ -730,15 +749,25 @@ int verify_hash(const char *file, const unsigned char *hash, int size,
>   		return -1;
>   #endif
>   	} else if (sig[1] == DIGSIG_VERSION_2) {
> -		return verify_hash_v2(file, hash, size, sig, siglen);
> +		return verify_hash_v2(public_keys, file, hash, size,
> +				      sig, siglen);
>   	} else if (sig[1] == DIGSIG_VERSION_3) {
> -		return verify_hash_v3(file, hash, size, sig, siglen);
> +		return verify_hash_v3(public_keys, file, hash, size,
> +				      sig, siglen);
>   	} else
>   		return -1;
>   }
>   
> -int ima_verify_signature(const char *file, unsigned char *sig, int siglen,
> -			 unsigned char *digest, int digestlen)
> +__attribute__((deprecated)) int verify_hash(const char *file,
> +					    const unsigned char *hash, int size,
> +					    unsigned char *sig, int siglen)
> +{
> +	return imaevm_verify_hash(g_public_keys, file, hash, size, sig, siglen);
> +}
> +
> +int ima_verify_signature2(void *public_keys, const char *file,
> +			  unsigned char *sig, int siglen,
> +			  unsigned char *digest, int digestlen)
>   {
>   	unsigned char hash[MAX_DIGEST_SIZE];
>   	int hashlen, sig_hash_algo;
> @@ -766,14 +795,26 @@ int ima_verify_signature(const char *file, unsigned char *sig, int siglen,
>   	 * measurement list, not by calculating the local file digest.
>   	 */
>   	if (digest && digestlen > 0)
> -		return verify_hash(file, digest, digestlen, sig, siglen);
> +		return imaevm_verify_hash(public_keys, file, digest, digestlen,
> +					  sig, siglen);
>   
>   	hashlen = ima_calc_hash(file, hash);
>   	if (hashlen <= 1)
>   		return hashlen;
>   	assert(hashlen <= sizeof(hash));
>   
> -	return verify_hash(file, hash, hashlen, sig, siglen);
> +	return imaevm_verify_hash(public_keys, file, hash, hashlen,
> +				  sig, siglen);
> +}
> +
> +__attribute__((deprecated)) int ima_verify_signature(const char *file,
> +						     unsigned char *sig,
> +						     int siglen,
> +						     unsigned char *digest,
> +						     int digestlen)
> +{
> +	return ima_verify_signature2(g_public_keys, file, sig, siglen,
> +				     digest, digestlen);
>   }
>   
>   #if CONFIG_SIGV1