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

Mimi Zohar
2023-11-19T16:51:18Z

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".

To avoid library incompatablity, 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 | 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)
{
struct public_key_entry *entry;
char *tmp_keyfiles, *keyfiles_free;
@@ -420,6 +420,11 @@ 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 +449,24 @@ 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)
- free_public_keys(g_public_keys);
+ free_public_keys(public_keys);
+ return err;
+}
+
+/*
+ * Global static variables are not concurrency-safe.
+ *
+ * Deprecate init_public_keys() usage.
+ */
+void init_public_keys(const char *keyfiles)
+{
+ init_public_keys2(keyfiles, (void **)&g_public_keys);
}

/*
@@ -466,7 +483,8 @@ 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(void *public_keys, const char *file,
+ const unsigned char *hash,
int size, unsigned char *sig, int siglen)
{
int ret = -1;
@@ -481,7 +499,7 @@ 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 +561,13 @@ 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(void *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 +576,8 @@ 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(void *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 +588,8 @@ 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 +732,9 @@ 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 verify_hash2(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 +753,29 @@ 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)
+/*
+ * Global static variables are not concurrency-safe.
+ *
+ * Deprecate verify_hash() usage.
+ */
+int verify_hash(const char *file, const unsigned char *hash, int size,
+ unsigned char *sig, int siglen)
+{
+ return verify_hash2(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 +803,27 @@ 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 verify_hash2(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 verify_hash2(public_keys, file, hash, hashlen, sig, siglen);
+}
+
+/*
+ * Global static variables are not concurrency-safe.
+ *
+ * Deprecate ima_verify_signature() usage.
+ */
+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
--
2.39.3