[PATCH v2] KEYS: trusted: allow trusted.ko to initialize w/o a TPM

[Jarkko Sakkinen]

Allow trusted.ko to initialize w/o a TPM. This commit adds checks to the
key type callbacks and exported functions to fail when a TPM is not
available.

Cc: James Morris <jmor...@namei.org>
Reported-by: Dan Williams <dan.j.willi...@intel.com>
Tested-by: Dan Williams <dan.j.willi...@intel.com>
Fixes: 240730437deb ("KEYS: trusted: explicitly use tpm_chip structure...")
Signed-off-by: Jarkko Sakkinen <jarkko.sakki...@linux.intel.com>
---
v2:
- Remove checks from the key type callbacks because the key type will
  not be registered.
- Cc to James Morris because hopefully we can land this 5.1.0.
 security/keys/trusted.c | 31 +++++++++++++++++++++++++------
 1 file changed, 25 insertions(+), 6 deletions(-)

diff --git a/security/keys/trusted.c b/security/keys/trusted.c
index ecec672d3a77..67c0e19a2125 100644
--- a/security/keys/trusted.c
+++ b/security/keys/trusted.c
@@ -135,6 +135,9 @@ int TSS_authhmac(unsigned char *digest, const unsigned char 
*key,
        int ret;
        va_list argp;
 
+       if (!chip)
+               return -ENODEV;
+
        sdesc = init_sdesc(hashalg);
        if (IS_ERR(sdesc)) {
                pr_info("trusted_key: can't alloc %s\n", hash_alg);
@@ -196,6 +199,9 @@ int TSS_checkhmac1(unsigned char *buffer,
        va_list argp;
        int ret;
 
+       if (!chip)
+               return -ENODEV;
+
        bufsize = LOAD32(buffer, TPM_SIZE_OFFSET);
        tag = LOAD16(buffer, 0);
        ordinal = command;
@@ -363,6 +369,9 @@ int trusted_tpm_send(unsigned char *cmd, size_t buflen)
 {
        int rc;
 
+       if (!chip)
+               return -ENODEV;
+
        dump_tpm_buf(cmd);
        rc = tpm_send(chip, cmd, buflen);
        dump_tpm_buf(cmd);
@@ -429,6 +438,9 @@ int oiap(struct tpm_buf *tb, uint32_t *handle, unsigned 
char *nonce)
 {
        int ret;
 
+       if (!chip)
+               return -ENODEV;
+
        INIT_BUF(tb);
        store16(tb, TPM_TAG_RQU_COMMAND);
        store32(tb, TPM_OIAP_SIZE);
@@ -1245,9 +1257,13 @@ static int __init init_trusted(void)
 {
        int ret;
 
+       /* encrypted_keys.ko depends on successful load of this module even if
+        * TPM is not used.
+        */
        chip = tpm_default_chip();
        if (!chip)
-               return -ENOENT;
+               return 0;
+
        ret = init_digests();
        if (ret < 0)
                goto err_put;
@@ -1263,16 +1279,19 @@ static int __init init_trusted(void)
 err_free:
        kfree(digests);
 err_put:
-       put_device(&chip->dev);
+       if (chip)
+               put_device(&chip->dev);
        return ret;
 }
 
 static void __exit cleanup_trusted(void)
 {
-       put_device(&chip->dev);
-       kfree(digests);
-       trusted_shash_release();
-       unregister_key_type(&key_type_trusted);
+       if (chip) {
+               put_device(&chip->dev);
+               kfree(digests);
+               trusted_shash_release();
+               unregister_key_type(&key_type_trusted);
+       }
 }
 
 late_initcall(init_trusted);
-- 
2.19.1