Re: [ima-evm-utils PATCH v2 11/13] Use a file specific hash algorithm variable for signing files

[Stefan Berger]

On 12/6/23 14:27, Mimi Zohar wrote:

Instead of relying on the library "imaevm_params.algo" global variable,
which is not concurrency-safe, define and use an evmctl file specific
hash algorithm variable.

Propagate using the file specific hash algorithm variable in sign_evm(),
sign_ima(), hash_ima(), and sign_hash() function.

Replace using the library function ima_calc_hash() with ima_calc_hash2().

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

Reviewed-by: Stefan Berger <stef...@linux.ibm.com>

---
  src/evmctl.c | 34 +++++++++++++++++-----------------
  1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/src/evmctl.c b/src/evmctl.c
index 9e1f4e33bc01..8eb2c46fbff0 100644
--- a/src/evmctl.c
+++ b/src/evmctl.c
@@ -140,6 +140,7 @@ static bool evm_immutable;
  static bool evm_portable;
  static bool veritysig;
  static bool hwtpm;
+static char *g_hash_algo = DEFAULT_HASH_ALGO;

#define HMAC_FLAG_NO_UUID 0x0001

  #define HMAC_FLAG_CAPS_SET    0x0002
@@ -564,18 +565,18 @@ out:
        return err;
  }

-static int sign_evm(const char *file, const char *key)

+static int sign_evm(const char *file, char *hash_algo, const char *key)
  {
        unsigned char hash[MAX_DIGEST_SIZE];
        unsigned char sig[MAX_SIGNATURE_SIZE];
        int len, err;

- len = calc_evm_hash(file, imaevm_params.hash_algo, hash);

+       len = calc_evm_hash(file, hash_algo, hash);
        if (len <= 1)
                return len;
        assert(len <= sizeof(hash));

- len = sign_hash(imaevm_params.hash_algo, hash, len, key, NULL, sig + 1);

+       len = sign_hash(hash_algo, hash, len, key, NULL, sig + 1);
        if (len <= 1)
                return len;
        assert(len < sizeof(sig));
@@ -609,10 +610,10 @@ static int hash_ima(const char *file)
  {
        unsigned char hash[MAX_DIGEST_SIZE + 2]; /* +2 byte xattr header */
        int len, err, offset;
-       int algo = imaevm_get_hash_algo(imaevm_params.hash_algo);
+       int algo = imaevm_get_hash_algo(g_hash_algo);

if (algo < 0) {

-               log_err("Unknown hash algo: %s\n", imaevm_params.hash_algo);
+               log_err("Unknown hash algo: %s\n", g_hash_algo);
                return -1;
        }
        if (algo > PKEY_HASH_SHA1) {
@@ -624,7 +625,7 @@ static int hash_ima(const char *file)
                offset = 1;
        }

- len = ima_calc_hash(file, hash + offset);

+       len = ima_calc_hash2(file, g_hash_algo, hash + offset);
        if (len <= 1)
                return len;
        assert(len + offset <= sizeof(hash));
@@ -632,7 +633,7 @@ static int hash_ima(const char *file)
        len += offset;

if (imaevm_params.verbose >= LOG_INFO)

-               log_info("hash(%s): ", imaevm_params.hash_algo);
+               log_info("hash(%s): ", g_hash_algo);

if (sigdump || imaevm_params.verbose >= LOG_INFO)

                imaevm_hexdump(hash, len);
@@ -650,18 +651,18 @@ static int hash_ima(const char *file)
        return 0;
  }

-static int sign_ima(const char *file, const char *key)

+static int sign_ima(const char *file, char *hash_algo, const char *key)
  {
        unsigned char hash[MAX_DIGEST_SIZE];
        unsigned char sig[MAX_SIGNATURE_SIZE];
        int len, err;

- len = ima_calc_hash(file, hash);

+       len = ima_calc_hash2(file, hash_algo, hash);
        if (len <= 1)
                return len;
        assert(len <= sizeof(hash));

- len = sign_hash(imaevm_params.hash_algo, hash, len, key, NULL, sig + 1);

+       len = sign_hash(hash_algo, hash, len, key, NULL, sig + 1);
        if (len <= 1)
                return len;
        assert(len < sizeof(sig));
@@ -751,7 +752,7 @@ static int sign_ima_file(const char *file)

key = imaevm_params.keyfile ? : "/etc/keys/privkey_evm.pem"; - return sign_ima(file, key);

+       return sign_ima(file, g_hash_algo, key);
  }

static int cmd_sign_ima(struct command *cmd)

@@ -854,7 +855,7 @@ static int cmd_sign_hash(struct command *cmd)
                        assert(hashlen / 2 <= sizeof(hash));
                        hex2bin(hash, line, hashlen / 2);

- siglen = sign_hash(imaevm_params.hash_algo, hash,

+                       siglen = sign_hash(g_hash_algo, hash,
                                           hashlen / 2, key, NULL, sig + 1);
                        sig[0] = EVM_IMA_XATTR_DIGSIG;
                }
@@ -874,7 +875,6 @@ static int cmd_sign_hash(struct command *cmd)
                print_usage(cmd);
                return -1;
        }
-
        return 0;
  }

@@ -886,7 +886,7 @@ static int sign_evm_path(const char *file)

        key = imaevm_params.keyfile ? : "/etc/keys/privkey_evm.pem";

if (digsig) {

-               err = sign_ima(file, key);
+               err = sign_ima(file, g_hash_algo, key);
                if (err)
                        return err;
        }
@@ -897,7 +897,7 @@ static int sign_evm_path(const char *file)
                        return err;
        }

- return sign_evm(file, key);

+       return sign_evm(file, g_hash_algo, key);
  }

static int cmd_sign_evm(struct command *cmd)

@@ -1426,7 +1426,7 @@ static int cmd_hmac_evm(struct command *cmd)
        key = imaevm_params.keyfile ? : "/etc/keys/privkey_evm.pem";

if (digsig) {

-               err = sign_ima(file, key);
+               err = sign_ima(file, g_hash_algo, key);
                if (err)
                        return err;
        }
@@ -3087,7 +3087,7 @@ int main(int argc, char *argv[])
                        sigdump = 1;
                        break;
                case 'a':
-                       imaevm_params.hash_algo = optarg;
+                       g_hash_algo = optarg;
                        break;
                case 'p':
                        if (optarg)