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 v6:
- remove ifdef CONFIG_IMA_TRUSTED_KEYRING in C code - Dmitry
- update Kconfig dependency and help
- select KEYS_DEBUG_PROC_KEYS - Dmitry

Changelog v5:
- Move integrity_init_keyring() to init_ima() - Dmitry
- reset keyring[id] on failure - Dmitry

Changelog v1:
- don't link IMA trusted keyring to user 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)
- only make the IMA keyring a trusted keyring (reported-by D. Kastatkin)
- define stub integrity_init_keyring() definition based on
  CONFIG_INTEGRITY_SIGNATURE, not CONFIG_INTEGRITY_ASYMMETRIC_KEYS.
  (reported-by Jim Davis)

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Acked-by: David Howells <dhowells@redhat.com>

diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
index b4af4ebc5be284d7f2665a5266be6a5bf267a683..8d4fbff8b87ca80460c9192610c01add6a150aa0 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>
 
@@ -24,7 +26,11 @@ static struct key *keyring[INTEGRITY_KEYRING_MAX];
 static const char *keyring_name[INTEGRITY_KEYRING_MAX] = {
        "_evm",
        "_module",
+#ifndef CONFIG_IMA_TRUSTED_KEYRING
        "_ima",
+#else
+       ".ima",
+#endif
 };
 
 int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
@@ -56,3 +62,25 @@ 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();
+       int err = 0;
+
+       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_USR_WRITE | KEY_USR_SEARCH),
+                                   KEY_ALLOC_NOT_IN_QUOTA, NULL);
+       if (!IS_ERR(keyring[id]))
+               set_bit(KEY_FLAG_TRUSTED_ONLY, &keyring[id]->flags);
+       else {
+               err = PTR_ERR(keyring[id]);
+               pr_info("Can't allocate %s keyring (%d)\n",
+                       keyring_name[id], err);
+               keyring[id] = NULL;
+       }
+       return err;
+}

diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig
index 81a27971d884215bc20e71d756f6778893ae1d67..08758fbd496f90c9176a726d3f48b7d91bb3e82a 100644 (file)
--- a/security/integrity/ima/Kconfig
+++ b/security/integrity/ima/Kconfig
@@ -123,3 +123,13 @@ 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
+       depends on INTEGRITY_ASYMMETRIC_KEYS
+       select KEYS_DEBUG_PROC_KEYS
+       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.h b/security/integrity/ima/ima.h
index f79fa8be203cd3703ad1a7fedddfe7037f602cdd..c42056edfc97699a7e85d7c1826614ef3686981f 100644 (file)
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -249,4 +249,16 @@ static inline int security_filter_rule_match(u32 secid, u32 field, u32 op,
        return -EINVAL;
 }
 #endif /* CONFIG_IMA_LSM_RULES */
+
+#ifdef CONFIG_IMA_TRUSTED_KEYRING
+static inline int ima_init_keyring(const unsigned int id)
+{
+       return integrity_init_keyring(id);
+}
+#else
+static inline int ima_init_keyring(const unsigned int id)
+{
+       return 0;
+}
+#endif /* CONFIG_IMA_TRUSTED_KEYRING */
 #endif

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index f474c608fa1194ebde04e21f2bdabc5be64c5d4a..0d696431209c09e1ac3f1c55145544648dbfa3be 100644 (file)
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -325,8 +325,14 @@ static int __init init_ima(void)
 
        hash_setup(CONFIG_IMA_DEFAULT_HASH);
        error = ima_init();
-       if (!error)
-               ima_initialized = 1;
+       if (error)
+               goto out;
+
+       error = ima_init_keyring(INTEGRITY_KEYRING_IMA);
+       if (error)
+               goto out;
+       ima_initialized = 1;
+out:
        return error;
 }
 

diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
index 33c0a70f6b15a66a7b024aa8fbb534d72c76c898..09c440d9aaee5b3c1624a93c7cebd45f3cf0d1c6 100644 (file)
--- a/security/integrity/integrity.h
+++ b/security/integrity/integrity.h
@@ -124,6 +124,7 @@ struct integrity_iint_cache *integrity_iint_find(struct inode *inode);
 int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
                            const char *digest, int digestlen);
 
+int integrity_init_keyring(const unsigned int id);
 #else
 
 static inline int integrity_digsig_verify(const unsigned int id,
@@ -133,6 +134,10 @@ static inline int integrity_digsig_verify(const unsigned int id,
        return -EOPNOTSUPP;
 }
 
+static inline int integrity_init_keyring(const unsigned int id)
+{
+       return 0;
+}
 #endif /* CONFIG_INTEGRITY_SIGNATURE */
 
 #ifdef CONFIG_INTEGRITY_ASYMMETRIC_KEYS