[PATCH v7 05/14] 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.ibm.com>
Signed-off-by: Mimi Zohar <zo...@linux.vnet.ibm.com>
---
 security/integrity/digsig.c    | 28 +++++++++++++++++++++-------
 security/integrity/integrity.h |  6 ++++++
 2 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
index 9bb0a7f2863e..2a60151af0c5 100644
--- a/security/integrity/digsig.c
+++ b/security/integrity/digsig.c
@@ -49,11 +49,10 @@ 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] =
@@ -62,17 +61,32 @@ 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;
+
+       if (siglen < 2)
+               return -EINVAL;
+
+       keyring = integrity_keyring_from_id(id);
+       if (IS_ERR(keyring))
+               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,
+               return digsig_verify(keyring, sig + 1, siglen - 1,
                                     digest, digestlen);
        case 2:
-               return asymmetric_verify(keyring[id], sig, siglen,
+               return asymmetric_verify(keyring, sig, siglen,
                                         digest, digestlen);
        }
 
diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
index 714fe2e135c7..d4f676906442 100644
--- a/security/integrity/integrity.h
+++ b/security/integrity/integrity.h
@@ -152,6 +152,7 @@ extern struct dentry *integrity_dir;
 
 #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);
 
@@ -159,6 +160,11 @@ int __init integrity_init_keyring(const unsigned int id);
 int __init integrity_load_x509(const unsigned int id, const char *path);
 #else
 
+static inline struct key *integrity_keyring_from_id(const unsigned int id)
+{
+       return ERR_PTR(-EINVAL);
+}
+
 static inline int integrity_digsig_verify(const unsigned int id,
                                          const char *sig, int siglen,
                                          const char *digest, int digestlen)