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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>
This commit is contained in:
David Howells 2019-08-19 17:17:55 -07:00 committed by James Morris
parent 794edf30ee
commit 20657f66ef
3 changed files with 18 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/security.h
View File

@ -113,6 +113,7 @@ enum lockdown_reason {
LOCKDOWN_ACPI_TABLES, LOCKDOWN_ACPI_TABLES,
LOCKDOWN_PCMCIA_CIS, LOCKDOWN_PCMCIA_CIS,
LOCKDOWN_TIOCSSERIAL, LOCKDOWN_TIOCSSERIAL,
LOCKDOWN_MODULE_PARAMETERS,
LOCKDOWN_INTEGRITY_MAX, LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_CONFIDENTIALITY_MAX, LOCKDOWN_CONFIDENTIALITY_MAX,
}; };

17
kernel/params.c
View File

@ -12,6 +12,7 @@
#include <linux/err.h> #include <linux/err.h>
#include <linux/slab.h> #include <linux/slab.h>
#include <linux/ctype.h> #include <linux/ctype.h>
#include <linux/security.h>
#ifdef CONFIG_SYSFS #ifdef CONFIG_SYSFS
/* Protects all built-in parameters, modules use their own param_lock */ /* 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); 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) { if (kp->flags & KERNEL_PARAM_FL_UNSAFE) {
pr_notice("Setting dangerous option %s - tainting kernel\n", pr_notice("Setting dangerous option %s - tainting kernel\n",
kp->name); kp->name);
add_taint(TAINT_USER, LOCKDEP_STILL_OK); add_taint(TAINT_USER, LOCKDEP_STILL_OK);
} }
return true;
} }
static int parse_one(char *param, static int parse_one(char *param,
@ -132,8 +139,10 @@ static int parse_one(char *param,
pr_debug("handling %s with %p\n", param, pr_debug("handling %s with %p\n", param,
params[i].ops->set); params[i].ops->set);
kernel_param_lock(params[i].mod); kernel_param_lock(params[i].mod);
param_check_unsafe(&params[i]); if (param_check_unsafe(&params[i]))
err = params[i].ops->set(val, &params[i]); err = params[i].ops->set(val, &params[i]);
else
err = -EPERM;
kernel_param_unlock(params[i].mod); kernel_param_unlock(params[i].mod);
return err; return err;
} }
@ -553,8 +562,10 @@ static ssize_t param_attr_store(struct module_attribute *mattr,
return -EPERM; return -EPERM;
kernel_param_lock(mk->mod); kernel_param_lock(mk->mod);
param_check_unsafe(attribute->param); if (param_check_unsafe(attribute->param))
err = attribute->param->ops->set(buf, attribute->param); err = attribute->param->ops->set(buf, attribute->param);
else
err = -EPERM;
kernel_param_unlock(mk->mod); kernel_param_unlock(mk->mod);
if (!err) if (!err)
return len; return len;

1
security/lockdown/lockdown.c
View File

@ -28,6 +28,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_ACPI_TABLES] = "modifying ACPI tables", [LOCKDOWN_ACPI_TABLES] = "modifying ACPI tables",
[LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage", [LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage",
[LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO", [LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO",
[LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters",
[LOCKDOWN_INTEGRITY_MAX] = "integrity", [LOCKDOWN_INTEGRITY_MAX] = "integrity",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
}; };