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    Subject[PATCH V40 19/29] lockdown: Lock down module params that specify hardware parameters (eg. ioport)
    From
    From: David Howells <dhowells@redhat.com>

    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>
    ---
    include/linux/security.h | 1 +
    kernel/params.c | 21 ++++++++++++++++-----
    security/lockdown/lockdown.c | 1 +
    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",
    };
    --
    2.23.0.rc1.153.gdeed80330f-goog
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