[PATCH v5 14/18] integrity: Introduce integrity_keyring_from_id

[Thiago Jung Bauermann]

IMA will need to obtain the keyring used to verify file signatures so that
it can verify the module-style signature appended to files.

Signed-off-by: Thiago Jung Bauermann <bauer...@linux.vnet.ibm.com>
---
 security/integrity/digsig.c    | 28 +++++++++++++++++++---------
 security/integrity/integrity.h |  1 +
 2 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
index 6f9e4ce568cd..935f1b3258e7 100644
--- a/security/integrity/digsig.c
+++ b/security/integrity/digsig.c
@@ -48,11 +48,10 @@ static bool init_keyring __initdata;
 #define restrict_link_to_ima restrict_link_by_builtin_trusted
 #endif
 
-int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
-                           const char *digest, int digestlen)
+struct key *integrity_keyring_from_id(const unsigned int id)
 {
-       if (id >= INTEGRITY_KEYRING_MAX || siglen < 2)
-               return -EINVAL;
+       if (id >= INTEGRITY_KEYRING_MAX)
+               return ERR_PTR(-EINVAL);
 
        if (!keyring[id]) {
                keyring[id] =
@@ -61,18 +60,29 @@ int integrity_digsig_verify(const unsigned int id, const 
char *sig, int siglen,
                        int err = PTR_ERR(keyring[id]);
                        pr_err("no %s keyring: %d\n", keyring_name[id], err);
                        keyring[id] = NULL;
-                       return err;
+                       return ERR_PTR(err);
                }
        }
 
+       return keyring[id];
+}
+
+int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
+                           const char *digest, int digestlen)
+{
+       struct key *keyring = integrity_keyring_from_id(id);
+
+       if (IS_ERR(keyring) || siglen < 2)
+               return PTR_ERR(keyring);
+
        switch (sig[1]) {
        case 1:
                /* v1 API expect signature without xattr type */
-               return digsig_verify(keyring[id], sig + 1, siglen - 1,
-                                    digest, digestlen);
+               return digsig_verify(keyring, sig + 1, siglen - 1, digest,
+                                    digestlen);
        case 2:
-               return asymmetric_verify(keyring[id], sig, siglen,
-                                        digest, digestlen);
+               return asymmetric_verify(keyring, sig, siglen, digest,
+                                        digestlen);
        }
 
        return -EOPNOTSUPP;
diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
index dd7ac4bfc89a..657ce4558984 100644
--- a/security/integrity/integrity.h
+++ b/security/integrity/integrity.h
@@ -132,6 +132,7 @@ int integrity_kernel_read(struct file *file, loff_t offset,
 
 #ifdef CONFIG_INTEGRITY_SIGNATURE
 
+struct key *integrity_keyring_from_id(const unsigned int id);
 int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
                            const char *digest, int digestlen);