Require all keys added to the IMA keyring be signed by an
existing trusted key on the system trusted keyring.
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<zo...@linux.vnet.ibm.com>
---
security/integrity/digsig.c | 26 +++++++++++++++++++++++++-
security/integrity/ima/Kconfig | 8 ++++++++
security/integrity/ima/ima_appraise.c | 11 +++++++++++
security/integrity/integrity.h | 5 +++++
4 files changed, 49 insertions(+), 1 deletion(-)
diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
index b4af4eb..7da5f9c 100644
--- 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,
@@ -35,7 +41,7 @@ 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 +62,21 @@ 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();
+
+ 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
+ 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 81a2797..dad8d4c 100644
--- 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 d3113d4..003ff46 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -385,3 +385,14 @@ 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 33c0a70..09c440d 100644
--- 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
--
1.8.1.4
--
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