Messages in this thread Patch in this message | | | Subject | [PATCH 24/24] Lock down module params that specify hardware parameters (eg. ioport) | From | David Howells <> | Date | Wed, 05 Apr 2017 21:18:02 +0100 |
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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> ---
kernel/params.c | 27 ++++++++++++++++++++++----- 1 file changed, 22 insertions(+), 5 deletions(-)
diff --git a/kernel/params.c b/kernel/params.c index a6d6149c0fe6..04185c5aa929 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -108,13 +108,20 @@ 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, + const char *doing) { if (kp->flags & KERNEL_PARAM_FL_UNSAFE) { pr_warn("Setting dangerous option %s - tainting kernel\n", kp->name); add_taint(TAINT_USER, LOCKDEP_STILL_OK); } + + if (kp->flags & KERNEL_PARAM_FL_HWPARAM && kernel_is_locked_down()) { + pr_err("Command line-specified device addresses, irqs and dma channels are not permitted when the kernel is locked down (%s.%s)\n", doing, kp->name); + return false; + } + return true; } static int parse_one(char *param, @@ -144,8 +151,10 @@ 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(¶ms[i]); - err = params[i].ops->set(val, ¶ms[i]); + if (param_check_unsafe(¶ms[i], doing)) + err = params[i].ops->set(val, ¶ms[i]); + else + err = -EPERM; kernel_param_unlock(params[i].mod); return err; } @@ -608,6 +617,12 @@ static ssize_t param_attr_show(struct module_attribute *mattr, return count; } +#ifdef CONFIG_MODULES +#define mod_name(mod) (mod)->name +#else +#define mod_name(mod) "unknown" +#endif + /* sysfs always hands a nul-terminated string in buf. We rely on that. */ static ssize_t param_attr_store(struct module_attribute *mattr, struct module_kobject *mk, @@ -620,8 +635,10 @@ 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, mod_name(mk->mod))) + err = attribute->param->ops->set(buf, attribute->param); + else + err = -EPERM; kernel_param_unlock(mk->mod); if (!err) return len;
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