ima: measure and appraise the IMA policy itself

Add support for measuring and appraising the IMA policy itself.

Changelog v4:
- use braces on both if/else branches, even if single line on one of the
branches - Dmitry
- Use the id mapping - Dmitry

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: Petko Manolov <petkan@mip-labs.com>
Acked-by: Dmitry Kasatkin <dmitry.kasatkin@huawei.com>

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index bd97e0d..5d0f611 100644 (file)
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -149,6 +149,7 @@ enum ima_hooks {
        FIRMWARE_CHECK,
        KEXEC_KERNEL_CHECK,
        KEXEC_INITRAMFS_CHECK,
+       POLICY_CHECK,
        MAX_CHECK
 };
 
@@ -191,6 +192,7 @@ int ima_policy_show(struct seq_file *m, void *v);
 #define IMA_APPRAISE_LOG       0x04
 #define IMA_APPRAISE_MODULES   0x08
 #define IMA_APPRAISE_FIRMWARE  0x10
+#define IMA_APPRAISE_POLICY    0x20
 
 #ifdef CONFIG_IMA_APPRAISE
 int ima_appraise_measurement(enum ima_hooks func,

diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index a6c61b3..60d011a 100644 (file)
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -325,10 +325,18 @@ static ssize_t ima_write_policy(struct file *file, const char __user *buf,
        if (result < 0)
                goto out_free;
 
-       if (data[0] == '/')
+       if (data[0] == '/') {
                result = ima_read_policy(data);
-       else 
+       } else if (ima_appraise & IMA_APPRAISE_POLICY) {
+               pr_err("IMA: signed policy file (specified as an absolute pathname) required\n");
+               integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL,
+                                   "policy_update", "signed policy required",
+                                   1, 0);
+               if (ima_appraise & IMA_APPRAISE_ENFORCE)
+                       result = -EACCES;
+       } else {
                result = ima_parse_add_rule(data);
+       }
        mutex_unlock(&ima_write_mutex);
 out_free:
        kfree(data);

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index f764881..391f417 100644 (file)
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -344,6 +344,7 @@ static int read_idmap[READING_MAX_ID] = {
        [READING_MODULE] = MODULE_CHECK,
        [READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK,
        [READING_KEXEC_INITRAMFS] = KEXEC_INITRAMFS_CHECK,
+       [READING_POLICY] = POLICY_CHECK
 };
 
 /**

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 646134c..c1b5d00 100644 (file)
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -114,6 +114,7 @@ static struct ima_rule_entry default_measurement_rules[] = {
         .uid = GLOBAL_ROOT_UID, .flags = IMA_FUNC | IMA_INMASK | IMA_UID},
        {.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
        {.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC},
+       {.action = MEASURE, .func = POLICY_CHECK, .flags = IMA_FUNC},
 };
 
 static struct ima_rule_entry default_appraise_rules[] = {
@@ -618,6 +619,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
                        else if (strcmp(args[0].from, "KEXEC_INITRAMFS_CHECK")
                                 == 0)
                                entry->func = KEXEC_INITRAMFS_CHECK;
+                       else if (strcmp(args[0].from, "POLICY_CHECK") == 0)
+                               entry->func = POLICY_CHECK;
                        else
                                result = -EINVAL;
                        if (!result)
@@ -776,6 +779,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
                temp_ima_appraise |= IMA_APPRAISE_MODULES;
        else if (entry->func == FIRMWARE_CHECK)
                temp_ima_appraise |= IMA_APPRAISE_FIRMWARE;
+       else if (entry->func == POLICY_CHECK)
+               temp_ima_appraise |= IMA_APPRAISE_POLICY;
        audit_log_format(ab, "res=%d", !result);
        audit_log_end(ab);
        return result;
@@ -862,7 +867,8 @@ static char *mask_tokens[] = {
 enum {
        func_file = 0, func_mmap, func_bprm,
        func_module, func_firmware, func_post,
-       func_kexec_kernel, func_kexec_initramfs
+       func_kexec_kernel, func_kexec_initramfs,
+       func_policy
 };
 
 static char *func_tokens[] = {
@@ -873,6 +879,7 @@ static char *func_tokens[] = {
        "FIRMWARE_CHECK",
        "KEXEC_KERNEL_CHECK",
        "KEXEC_INITRAMFS_CHECK",
+       "POLICY_CHECK",
        "POST_SETATTR"
 };
 
@@ -944,6 +951,9 @@ static void policy_func_show(struct seq_file *m, enum ima_hooks func)
        case KEXEC_INITRAMFS_CHECK:
                seq_printf(m, pt(Opt_func), ft(func_kexec_initramfs));
                break;
+       case POLICY_CHECK:
+               seq_printf(m, pt(Opt_func), ft(func_policy));
+               break;
        default:
                snprintf(tbuf, sizeof(tbuf), "%d", func);
                seq_printf(m, pt(Opt_func), tbuf);