Re: [ima-evm-utils PATCH 03/12] Update library function definitions to include a "public_keys" parameter

Stefan Berger
2023-11-22T13:07:27Z

On 11/19/23 11:50, 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 init_public_keys2(), verify_hash2(), and ima_verify_signature2()
> functions. Update static function defintions to include "public_keys".

-> definitions

>
> To avoid library incompatablity, make the existing functions -

-> incompatibility

> init_public_keys(), verify_hash(), ima_verify_signature() - wrappers
> for the new function versions.
>
> Deprecate init_public_keys(), verify_hash(), ima_verify_signature()
> functions.

It may be worth considering adding __attribute__((deprecated)) to those
functions.

>
> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
> ---
> src/imaevm.h | 2 ++
> src/libimaevm.c | 94 +++++++++++++++++++++++++++++++++++++------------
> 2 files changed, 74 insertions(+), 22 deletions(-)
>
> diff --git a/src/imaevm.h b/src/imaevm.h
> index 828976e52881..146123ba5c42 100644
> --- a/src/imaevm.h
> +++ b/src/imaevm.h
> @@ -249,8 +249,10 @@ 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);
> +int ima_verify_signature2(void *public_keys, const char *file, unsigned char *sig, int siglen, unsigned char *digest, int digestlen);
> void free_public_keys(void *public_keys);
> void init_public_keys(const char *keyfiles);
> +int init_public_keys2(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 74e9d09b1f05..bf8c99770ddc 100644
> --- a/src/libimaevm.c
> +++ b/src/libimaevm.c
> @@ -372,12 +372,12 @@ 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(void *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 != NULL; entry = entry->next) {
> + for (entry = public_keys; entry != NULL; entry = entry->next) {
> if (entry->keyid == keyid)
> return entry->key;
> i++;
> @@ -394,7 +394,7 @@ 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 +412,7 @@ void free_public_keys(void *public_keys)
> }
> }
>
> -void init_public_keys(const char *keyfiles)
> +int init_public_keys2(const char *keyfiles, void **public_keys)

Even though callers of the public APIs may get void *, inside the
library this can be passed around with its concrete type.