From: Mimi Zohar <zohar@linux.ibm.com>
To: linux-integrity@vger.kernel.org
Cc: linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org, Jessica Yu <jeyu@kernel.org>,
Luis Chamberlain <mcgrof@kernel.org>,
David Howells <dhowells@redhat.com>,
Seth Forshee <seth.forshee@canonical.com>,
Justin Forbes <jforbes@redhat.com>,
Matthew Garrett <mjg59@google.com>,
Mimi Zohar <zohar@linux.ibm.com>
Subject: [PATCH] x86/ima: require signed kernel modules
Date: Thu, 31 Jan 2019 14:18:59 -0500 [thread overview]
Message-ID: <1548962339-10681-2-git-send-email-zohar@linux.ibm.com> (raw)
In-Reply-To: <1548962339-10681-1-git-send-email-zohar@linux.ibm.com>
Require signed kernel modules on systems with secure boot mode enabled.
To coordinate between appended kernel module signatures and IMA
signatures, only define an IMA MODULE_CHECK policy rule if
CONFIG_MODULE_SIG is not enabled.
This patch defines a function named set_module_sig_required() and renames
is_module_sig_enforced() to is_module_sig_enforced_or_required(). The
call to set_module_sig_required() is dependent on CONFIG_IMA_ARCH_POLICY
being enabled.
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
---
arch/x86/kernel/ima_arch.c | 9 ++++++++-
include/linux/module.h | 7 ++++++-
kernel/module.c | 15 +++++++++++----
security/integrity/ima/ima_main.c | 2 +-
4 files changed, 26 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kernel/ima_arch.c b/arch/x86/kernel/ima_arch.c
index e47cd9390ab4..96a023238a83 100644
--- a/arch/x86/kernel/ima_arch.c
+++ b/arch/x86/kernel/ima_arch.c
@@ -64,12 +64,19 @@ static const char * const sb_arch_rules[] = {
"appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig",
#endif /* CONFIG_KEXEC_VERIFY_SIG */
"measure func=KEXEC_KERNEL_CHECK",
+#if !IS_ENABLED(CONFIG_MODULE_SIG)
+ "appraise func=MODULE_CHECK appraise_type=imasig",
+#endif
+ "measure func=MODULE_CHECK",
NULL
};
const char * const *arch_get_ima_policy(void)
{
- if (IS_ENABLED(CONFIG_IMA_ARCH_POLICY) && arch_ima_get_secureboot())
+ if (IS_ENABLED(CONFIG_IMA_ARCH_POLICY) && arch_ima_get_secureboot()) {
+ if (IS_ENABLED(CONFIG_MODULE_SIG))
+ set_module_sig_required();
return sb_arch_rules;
+ }
return NULL;
}
diff --git a/include/linux/module.h b/include/linux/module.h
index 8fa38d3e7538..af51c8ec755f 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -659,7 +659,8 @@ static inline bool is_livepatch_module(struct module *mod)
}
#endif /* CONFIG_LIVEPATCH */
-bool is_module_sig_enforced(void);
+bool is_module_sig_enforced_or_required(void);
+void set_module_sig_required(void);
#else /* !CONFIG_MODULES... */
@@ -780,6 +781,10 @@ static inline bool is_module_sig_enforced(void)
return false;
}
+static inline void set_module_sig_required(void)
+{
+}
+
/* Dereference module function descriptor */
static inline
void *dereference_module_function_descriptor(struct module *mod, void *ptr)
diff --git a/kernel/module.c b/kernel/module.c
index 2ad1b5239910..70a9709d19eb 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -275,16 +275,23 @@ static void module_assert_mutex_or_preempt(void)
static bool sig_enforce = IS_ENABLED(CONFIG_MODULE_SIG_FORCE);
module_param(sig_enforce, bool_enable_only, 0644);
+static bool sig_required;
/*
* Export sig_enforce kernel cmdline parameter to allow other subsystems rely
* on that instead of directly to CONFIG_MODULE_SIG_FORCE config.
*/
-bool is_module_sig_enforced(void)
+bool is_module_sig_enforced_or_required(void)
{
- return sig_enforce;
+ return sig_enforce || sig_required;
}
-EXPORT_SYMBOL(is_module_sig_enforced);
+EXPORT_SYMBOL(is_module_sig_enforced_or_required);
+
+void set_module_sig_required(void)
+{
+ sig_required = true;
+}
+EXPORT_SYMBOL(set_module_sig_required);
/* Block module loading/unloading? */
int modules_disabled = 0;
@@ -2789,7 +2796,7 @@ static int module_sig_check(struct load_info *info, int flags)
}
/* Not having a signature is only an error if we're strict. */
- if (err == -ENOKEY && !is_module_sig_enforced())
+ if (err == -ENOKEY && !is_module_sig_enforced_or_required())
err = 0;
return err;
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 357edd140c09..bbaf87f688be 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -563,7 +563,7 @@ int ima_load_data(enum kernel_load_data_id id)
}
break;
case LOADING_MODULE:
- sig_enforce = is_module_sig_enforced();
+ sig_enforce = is_module_sig_enforced_or_required();
if (ima_enforce && (!sig_enforce
&& (ima_appraise & IMA_APPRAISE_MODULES))) {
--
2.7.5
next prev parent reply other threads:[~2019-01-31 19:19 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-31 19:18 [PATCH] ima: requiring signed kernel modules Mimi Zohar
2019-01-31 19:18 ` Mimi Zohar [this message]
2019-02-04 20:38 ` [PATCH] x86/ima: require " Luis Chamberlain
2019-02-04 22:05 ` Mimi Zohar
2019-02-04 22:30 ` Luis Chamberlain
2019-02-05 12:24 ` Mimi Zohar
2019-02-05 21:13 ` Luis Chamberlain
2019-02-05 23:13 ` Mimi Zohar
2019-02-05 15:18 ` Seth Forshee
2019-02-05 16:47 ` Mimi Zohar
2019-02-05 18:32 ` Seth Forshee
2019-02-05 18:52 ` Mimi Zohar
2019-02-08 19:21 ` Seth Forshee
2019-02-10 15:39 ` Mimi Zohar
2019-02-05 16:10 ` Nayna
2019-02-11 15:56 ` Jessica Yu
2019-02-11 16:19 ` Mimi Zohar
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