#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/module_signature.h>
#include <linux/string.h>
#include <linux/verification.h>
#include <linux/security.h>
#include <crypto/public_key.h>
#include <uapi/linux/module.h>
#include "internal.h"
#undef MODULE_PARAM_PREFIX
#define MODULE_PARAM_PREFIX "module."
static bool sig_enforce = IS_ENABLED(CONFIG_MODULE_SIG_FORCE);
module_param(sig_enforce, bool_enable_only, 0644);
bool is_module_sig_enforced(void)
{
return sig_enforce;
}
EXPORT_SYMBOL(is_module_sig_enforced);
void set_module_sig_enforced(void)
{
sig_enforce = true;
}
int mod_verify_sig(const void *mod, struct load_info *info)
{
struct module_signature ms;
size_t sig_len, modlen = info->len;
int ret;
pr_devel("==>%s(,%zu)\n", __func__, modlen);
if (modlen <= sizeof(ms))
return -EBADMSG;
memcpy(&ms, mod + (modlen - sizeof(ms)), sizeof(ms));
ret = mod_check_sig(&ms, modlen, "module");
if (ret)
return ret;
sig_len = be32_to_cpu(ms.sig_len);
modlen -= sig_len + sizeof(ms);
info->len = modlen;
return verify_pkcs7_signature(mod, modlen, mod + modlen, sig_len,
VERIFY_USE_SECONDARY_KEYRING,
VERIFYING_MODULE_SIGNATURE,
NULL, NULL);
}
int module_sig_check(struct load_info *info, int flags)
{
int err = -ENODATA;
const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1;
const char *reason;
const void *mod = info->hdr;
bool mangled_module = flags & (MODULE_INIT_IGNORE_MODVERSIONS |
MODULE_INIT_IGNORE_VERMAGIC);
if (!mangled_module &&
info->len > markerlen &&
memcmp(mod + info->len - markerlen, MODULE_SIG_STRING, markerlen) == 0) {
info->len -= markerlen;
err = mod_verify_sig(mod, info);
if (!err) {
info->sig_ok = true;
return 0;
}
}
switch (err) {
case -ENODATA:
reason = "unsigned module";
break;
case -ENOPKG:
reason = "module with unsupported crypto";
break;
case -ENOKEY:
reason = "module with unavailable key";
break;
default:
return err;
}
if (is_module_sig_enforced()) {
pr_notice("Loading of %s is rejected\n", reason);
return -EKEYREJECTED;
}
return security_locked_down(LOCKDOWN_MODULE_SIGNATURE);
}