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authorDavid Howells <dhowells@redhat.com>2019-08-20 03:17:55 +0300
committerJames Morris <jmorris@namei.org>2019-08-20 07:54:16 +0300
commit20657f66ef52e5005369e4ef539d4cbf01eab10d (patch)
treef5f50d1c2f61821f69e41f1237cdafb446af8e5b
parent794edf30ee6cd088d5f4079b1d4a4cfe5371203e (diff)
downloadlinux-20657f66ef52e5005369e4ef539d4cbf01eab10d.tar.xz
lockdown: Lock down module params that specify hardware parameters (eg. ioport)
Provided an annotation for module parameters that specify hardware parameters (such as io ports, iomem addresses, irqs, dma channels, fixed dma buffers and other types). Suggested-by: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Matthew Garrett <mjg59@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Jessica Yu <jeyu@kernel.org> Signed-off-by: James Morris <jmorris@namei.org>
-rw-r--r--include/linux/security.h1
-rw-r--r--kernel/params.c21
-rw-r--r--security/lockdown/lockdown.c1
3 files changed, 18 insertions, 5 deletions
diff --git a/include/linux/security.h b/include/linux/security.h
index b4a85badb03a..1a3404f9c060 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -113,6 +113,7 @@ enum lockdown_reason {
LOCKDOWN_ACPI_TABLES,
LOCKDOWN_PCMCIA_CIS,
LOCKDOWN_TIOCSSERIAL,
+ LOCKDOWN_MODULE_PARAMETERS,
LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_CONFIDENTIALITY_MAX,
};
diff --git a/kernel/params.c b/kernel/params.c
index cf448785d058..8e56f8b12d8f 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -12,6 +12,7 @@
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/ctype.h>
+#include <linux/security.h>
#ifdef CONFIG_SYSFS
/* Protects all built-in parameters, modules use their own param_lock */
@@ -96,13 +97,19 @@ bool parameq(const char *a, const char *b)
return parameqn(a, b, strlen(a)+1);
}
-static void param_check_unsafe(const struct kernel_param *kp)
+static bool param_check_unsafe(const struct kernel_param *kp)
{
+ if (kp->flags & KERNEL_PARAM_FL_HWPARAM &&
+ security_locked_down(LOCKDOWN_MODULE_PARAMETERS))
+ return false;
+
if (kp->flags & KERNEL_PARAM_FL_UNSAFE) {
pr_notice("Setting dangerous option %s - tainting kernel\n",
kp->name);
add_taint(TAINT_USER, LOCKDEP_STILL_OK);
}
+
+ return true;
}
static int parse_one(char *param,
@@ -132,8 +139,10 @@ static int parse_one(char *param,
pr_debug("handling %s with %p\n", param,
params[i].ops->set);
kernel_param_lock(params[i].mod);
- param_check_unsafe(&params[i]);
- err = params[i].ops->set(val, &params[i]);
+ if (param_check_unsafe(&params[i]))
+ err = params[i].ops->set(val, &params[i]);
+ else
+ err = -EPERM;
kernel_param_unlock(params[i].mod);
return err;
}
@@ -553,8 +562,10 @@ static ssize_t param_attr_store(struct module_attribute *mattr,
return -EPERM;
kernel_param_lock(mk->mod);
- param_check_unsafe(attribute->param);
- err = attribute->param->ops->set(buf, attribute->param);
+ if (param_check_unsafe(attribute->param))
+ err = attribute->param->ops->set(buf, attribute->param);
+ else
+ err = -EPERM;
kernel_param_unlock(mk->mod);
if (!err)
return len;
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 771c77f9c04a..0fa434294667 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -28,6 +28,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_ACPI_TABLES] = "modifying ACPI tables",
[LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage",
[LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO",
+ [LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters",
[LOCKDOWN_INTEGRITY_MAX] = "integrity",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};