[PATCH v3 3/7] ima: based on policy require signed kexec kernel images
Mimi Zohar
zohar at linux.vnet.ibm.com
Thu May 24 11:09:32 UTC 2018
The original kexec_load syscall can not verify file signatures. This
patch differentiates between the kexec_load and kexec_file_load
syscalls.
Signed-off-by: Mimi Zohar <zohar at linux.vnet.ibm.com>
Cc: Eric Biederman <ebiederm at xmission.com>
Cc: Luis R. Rodriguez <mcgrof at kernel.org>
Cc: Kees Cook <keescook at chromium.org>
Cc: David Howells <dhowells at redhat.com>
Changelog v3:
- use switch/case
---
security/integrity/ima/ima.h | 1 +
security/integrity/ima/ima_main.c | 22 +++++++++++++++++-----
security/integrity/ima/ima_policy.c | 2 ++
3 files changed, 20 insertions(+), 5 deletions(-)
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 354bb5716ce3..78c15264b17b 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -232,6 +232,7 @@ int ima_policy_show(struct seq_file *m, void *v);
#define IMA_APPRAISE_MODULES 0x08
#define IMA_APPRAISE_FIRMWARE 0x10
#define IMA_APPRAISE_POLICY 0x20
+#define IMA_APPRAISE_KEXEC 0x40
#ifdef CONFIG_IMA_APPRAISE
int ima_appraise_measurement(enum ima_hooks func,
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index eeb7075868db..fbbcc02a1380 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -432,15 +432,27 @@ void ima_post_path_mknod(struct dentry *dentry)
*/
int ima_read_data(struct file *file, enum kernel_read_file_id read_id)
{
- bool sig_enforce = is_module_sig_enforced();
+ bool sig_enforce;
- if (!file && read_id == READING_MODULE) {
- if (!sig_enforce && (ima_appraise & IMA_APPRAISE_MODULES) &&
- (ima_appraise & IMA_APPRAISE_ENFORCE)) {
+ if ((ima_appraise & IMA_APPRAISE_ENFORCE) != IMA_APPRAISE_ENFORCE)
+ return 0;
+
+ switch (read_id) {
+ case READING_MODULE:
+ sig_enforce = is_module_sig_enforced(); /* appended sig */
+ if (!file && !sig_enforce &&
+ (ima_appraise & IMA_APPRAISE_MODULES)) {
pr_err("impossible to appraise a module without a file descriptor. sig_enforce kernel parameter might help\n");
return -EACCES; /* INTEGRITY_UNKNOWN */
}
- return 0; /* We rely on module signature checking */
+ break;
+ case READING_KEXEC_IMAGE:
+ if (!file && (ima_appraise & IMA_APPRAISE_KEXEC)) {
+ pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file syscall.\n");
+ return -EACCES; /* INTEGRITY_UNKNOWN */
+ }
+ default:
+ break;
}
return 0;
}
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 8bbc18eb07eb..c27f6993b07a 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -448,6 +448,8 @@ static int ima_appraise_flag(enum ima_hooks func)
return IMA_APPRAISE_FIRMWARE;
else if (func == POLICY_CHECK)
return IMA_APPRAISE_POLICY;
+ else if (func == KEXEC_KERNEL_CHECK)
+ return IMA_APPRAISE_KEXEC;
return 0;
}
--
2.7.5
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