/**
* ima_load_data - appraise decision based on policy
* @id: kernel load data caller identifier
*
* Callers of this LSM hook can not measure, appraise, or audit the
* data provided by userspace. Enforce policy rules requring a file
* signature (eg. kexec'ed kernel image).
*
* For permission return 0, otherwise return -EACCES.
*/
int ima_load_data(enum kernel_load_data_id id)
{
bool sig_enforce;
if ((ima_appraise & IMA_APPRAISE_ENFORCE) != IMA_APPRAISE_ENFORCE)
return 0;
switch (id) {
case LOADING_KEXEC_IMAGE:
if (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) {
pr_err("Prevent firmware sysfs fallback loading.\n");
return -EACCES; /* INTEGRITY_UNKNOWN */
}
break;
case LOADING_MODULE:
sig_enforce = is_module_sig_enforced();
if (!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 */
}
default:
break;
}
return 0;
}
/**
* ima_read_file - pre-measure/appraise hook decision based on policy
* @file: pointer to the file to be measured/appraised/audit
* @read_id: caller identifier
*
* Permit reading a file based on policy. The policy rules are written
* in terms of the policy identifier. Appraising the integrity of
* a file requires a file descriptor.
*
* For permission return 0, otherwise return -EACCES.
*/
int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
{
bool sig_enforce = is_module_sig_enforced();
if (!file && read_id == READING_MODULE) {
if (!sig_enforce && (ima_appraise & IMA_APPRAISE_MODULES) &&
(ima_appraise & IMA_APPRAISE_ENFORCE)) {
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 */
}
return 0;
}