ima: define '_ima' as a builtin 'trusted' keyring

Require all keys added to the IMA keyring be signed by an
existing trusted key on the system trusted keyring.

Changelog:
- define stub integrity_init_keyring() function (reported-by Fengguang Wu)
- differentiate between regular and trusted keyring names.
- replace printk with pr_info (D. Kasatkin)

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>

diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
index b4af4ebc5be284d7f2665a5266be6a5bf267a683..77ca965ab684e67e2809dc16f024728d8df41c70 100644 (file)
--- a/security/integrity/digsig.c
+++ b/security/integrity/digsig.c
@@ -13,7 +13,9 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/err.h>
+#include <linux/sched.h>
 #include <linux/rbtree.h>
+#include <linux/cred.h>
 #include <linux/key-type.h>
 #include <linux/digsig.h>
 
@@ -21,11 +23,19 @@
 
 static struct key *keyring[INTEGRITY_KEYRING_MAX];
 
+#ifdef CONFIG_IMA_TRUSTED_KEYRING
+static const char *keyring_name[INTEGRITY_KEYRING_MAX] = {
+       ".evm",
+       ".module",
+       ".ima",
+};
+#else
 static const char *keyring_name[INTEGRITY_KEYRING_MAX] = {
        "_evm",
        "_module",
        "_ima",
 };
+#endif
 
 int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
                            const char *digest, int digestlen)
@@ -35,7 +45,7 @@ int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
 
        if (!keyring[id]) {
                keyring[id] =
-                       request_key(&key_type_keyring, keyring_name[id], NULL);
+                   request_key(&key_type_keyring, keyring_name[id], NULL);
                if (IS_ERR(keyring[id])) {
                        int err = PTR_ERR(keyring[id]);
                        pr_err("no %s keyring: %d\n", keyring_name[id], err);
@@ -56,3 +66,21 @@ int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
 
        return -EOPNOTSUPP;
 }
+
+int integrity_init_keyring(const unsigned int id)
+{
+       const struct cred *cred = current_cred();
+       const struct user_struct *user = cred->user;
+
+       keyring[id] = keyring_alloc(keyring_name[id], KUIDT_INIT(0),
+                                   KGIDT_INIT(0), cred,
+                                   ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
+                                    KEY_USR_VIEW | KEY_USR_READ),
+                                   KEY_ALLOC_NOT_IN_QUOTA, user->uid_keyring);
+       if (!IS_ERR(keyring[id]))
+               set_bit(KEY_FLAG_TRUSTED_ONLY, &keyring[id]->flags);
+       else
+               pr_info("Can't allocate %s keyring (%ld)\n",
+                       keyring_name[id], PTR_ERR(keyring[id]));
+       return 0;
+}

diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig
index 81a27971d884215bc20e71d756f6778893ae1d67..dad8d4ca2437fd608b73218993b23c3275c65b8d 100644 (file)
--- a/security/integrity/ima/Kconfig
+++ b/security/integrity/ima/Kconfig
@@ -123,3 +123,11 @@ config IMA_APPRAISE
          For more information on integrity appraisal refer to:
          <http://linux-ima.sourceforge.net>
          If unsure, say N.
+
+config IMA_TRUSTED_KEYRING
+       bool "Require all keys on the _ima keyring be signed"
+       depends on IMA_APPRAISE && SYSTEM_TRUSTED_KEYRING
+       default y
+       help
+          This option requires that all keys added to the _ima
+          keyring be signed by a key on the system trusted keyring.

diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 734e9468aca01c9a3724a57136f6d8bf371951f3..46353ee517f6f321a738b067584d7e62dd8872fe 100644 (file)
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -381,3 +381,14 @@ int ima_inode_removexattr(struct dentry *dentry, const char *xattr_name)
        }
        return result;
 }
+
+#ifdef CONFIG_IMA_TRUSTED_KEYRING
+static int __init init_ima_keyring(void)
+{
+       int ret;
+
+       ret = integrity_init_keyring(INTEGRITY_KEYRING_IMA);
+       return 0;
+}
+late_initcall(init_ima_keyring);
+#endif

diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
index 2fb5e53e927f2bf5432a34af1251c89f359d90f7..b9e7c133734a2dc5796fe98f5c15f8c81ebc5d26 100644 (file)
--- a/security/integrity/integrity.h
+++ b/security/integrity/integrity.h
@@ -137,12 +137,19 @@ static inline int integrity_digsig_verify(const unsigned int id,
 #ifdef CONFIG_INTEGRITY_ASYMMETRIC_KEYS
 int asymmetric_verify(struct key *keyring, const char *sig,
                      int siglen, const char *data, int datalen);
+
+int integrity_init_keyring(const unsigned int id);
 #else
 static inline int asymmetric_verify(struct key *keyring, const char *sig,
                                    int siglen, const char *data, int datalen)
 {
        return -EOPNOTSUPP;
 }
+
+static int integrity_init_keyring(const unsigned int id)
+{
+       return 0;
+}
 #endif
 
 #ifdef CONFIG_INTEGRITY_AUDIT