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lockdown: Lock down module params that specify hardware parameters (eg. ioport)

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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,
}; };

21
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",
}; };