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authorNayna Jain <nayna@linux.ibm.com>2018-10-09 23:00:34 +0530
committerMimi Zohar <zohar@linux.ibm.com>2018-12-11 07:10:33 -0500
commitb5ca117365d960fe5e4fe272bcc8142c28769383 (patch)
tree6e306a5c52ad13271a2d947c9a41922f1ddf709d /security
parent0914ade209c452cff6a29b1c0ae6fff3167fa1d0 (diff)
ima: prevent kexec_load syscall based on runtime secureboot flag
When CONFIG_KEXEC_VERIFY_SIG is enabled, the kexec_file_load syscall requires the kexec'd kernel image to be signed. Distros are concerned about totally disabling the kexec_load syscall. As a compromise, the kexec_load syscall will only be disabled when CONFIG_KEXEC_VERIFY_SIG is configured and the system is booted with secureboot enabled. This patch disables the kexec_load syscall only for systems booted with secureboot enabled. [zohar@linux.ibm.com: add missing mesage on kexec_load failure] Signed-off-by: Nayna Jain <nayna@linux.ibm.com> Cc: David Howells <dhowells@redhat.com> Cc: Eric Biederman <ebiederm@xmission.com> Cc: Peter Jones <pjones@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Dave Young <dyoung@redhat.com> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Diffstat (limited to 'security')
-rw-r--r--security/integrity/ima/ima_main.c19
1 files changed, 13 insertions, 6 deletions
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 1b88d58e1325..df0b2ee49fa2 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -505,20 +505,26 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
*/
int ima_load_data(enum kernel_load_data_id id)
{
- bool sig_enforce;
+ bool ima_enforce, sig_enforce;
- if ((ima_appraise & IMA_APPRAISE_ENFORCE) != IMA_APPRAISE_ENFORCE)
- return 0;
+ ima_enforce =
+ (ima_appraise & IMA_APPRAISE_ENFORCE) == IMA_APPRAISE_ENFORCE;
switch (id) {
case LOADING_KEXEC_IMAGE:
- if (ima_appraise & IMA_APPRAISE_KEXEC) {
+ if (IS_ENABLED(CONFIG_KEXEC_VERIFY_SIG)
+ && arch_ima_get_secureboot()) {
+ pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n");
+ return -EACCES;
+ }
+
+ if (ima_enforce && (ima_appraise & IMA_APPRAISE_KEXEC)) {
pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n");
return -EACCES; /* INTEGRITY_UNKNOWN */
}
break;
case LOADING_FIRMWARE:
- if (ima_appraise & IMA_APPRAISE_FIRMWARE) {
+ if (ima_enforce && (ima_appraise & IMA_APPRAISE_FIRMWARE)) {
pr_err("Prevent firmware sysfs fallback loading.\n");
return -EACCES; /* INTEGRITY_UNKNOWN */
}
@@ -526,7 +532,8 @@ int ima_load_data(enum kernel_load_data_id id)
case LOADING_MODULE:
sig_enforce = is_module_sig_enforced();
- if (!sig_enforce && (ima_appraise & IMA_APPRAISE_MODULES)) {
+ if (ima_enforce && (!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 */
}