From 730b69d225259565c705f5f5a11cb1aba69568f1 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Wed, 22 Oct 2008 10:00:22 -0500 Subject: module: check kernel param length at compile time, not runtime The kparam code tries to handle over-length parameter prefixes at runtime. Not only would I bet this has never been tested, it's not clear that truncating names is a good idea either. So let's check at compile time. We need to move the #define to moduleparam.h to do this, though. Signed-off-by: Rusty Russell --- include/linux/moduleparam.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'include/linux/moduleparam.h') diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h index ec624381c84..1eefe6d61b8 100644 --- a/include/linux/moduleparam.h +++ b/include/linux/moduleparam.h @@ -13,6 +13,9 @@ #define MODULE_PARAM_PREFIX KBUILD_MODNAME "." #endif +/* Chosen so that structs with an unsigned long line up. */ +#define MAX_PARAM_PREFIX_LEN (64 - sizeof(unsigned long)) + #ifdef MODULE #define ___module_cat(a,b) __mod_ ## a ## b #define __module_cat(a,b) ___module_cat(a,b) @@ -79,7 +82,8 @@ struct kparam_array #define __module_param_call(prefix, name, set, get, arg, perm) \ /* Default value instead of permissions? */ \ static int __param_perm_check_##name __attribute__((unused)) = \ - BUILD_BUG_ON_ZERO((perm) < 0 || (perm) > 0777 || ((perm) & 2)); \ + BUILD_BUG_ON_ZERO((perm) < 0 || (perm) > 0777 || ((perm) & 2)) \ + + BUILD_BUG_ON_ZERO(sizeof(""prefix) > MAX_PARAM_PREFIX_LEN); \ static const char __param_str_##name[] = prefix #name; \ static struct kernel_param __moduleparam_const __param_##name \ __used \ -- cgit v1.2.3-70-g09d2 From 67e67ceaac5bf55dbdceb704ff2d763d438b5373 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Wed, 22 Oct 2008 10:00:23 -0500 Subject: core_param() for genuinely core kernel parameters There are a lot of one-liner uses of __setup() in the kernel: they're cumbersome and not queryable (definitely not settable) via /sys. Yet it's ugly to simplify them to module_param(), because by default that inserts a prefix of the module name (usually filename). So, introduce a "core_param". The parameter gets no prefix, but appears in /sys/module/kernel/parameters/ (if non-zero perms arg). I thought about using the name "core", but that's more common than "kernel". And if you create a module called "kernel", you will die a horrible death. Signed-off-by: Rusty Russell --- include/linux/moduleparam.h | 19 +++++++++++++++++++ kernel/params.c | 14 +++++++------- 2 files changed, 26 insertions(+), 7 deletions(-) (limited to 'include/linux/moduleparam.h') diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h index 1eefe6d61b8..e4af3399ef4 100644 --- a/include/linux/moduleparam.h +++ b/include/linux/moduleparam.h @@ -104,6 +104,25 @@ struct kparam_array #define module_param(name, type, perm) \ module_param_named(name, name, type, perm) +#ifndef MODULE +/** + * core_param - define a historical core kernel parameter. + * @name: the name of the cmdline and sysfs parameter (often the same as var) + * @var: the variable + * @type: the type (for param_set_##type and param_get_##type) + * @perm: visibility in sysfs + * + * core_param is just like module_param(), but cannot be modular and + * doesn't add a prefix (such as "printk."). This is for compatibility + * with __setup(), and it makes sense as truly core parameters aren't + * tied to the particular file they're in. + */ +#define core_param(name, var, type, perm) \ + param_check_##type(name, &(var)); \ + __module_param_call("", name, param_set_##type, param_get_##type, \ + &var, perm) +#endif /* !MODULE */ + /* Actually copy string: maxlen param is usually sizeof(string). */ #define module_param_string(name, string, len, perm) \ static const struct kparam_string __param_string_##name \ diff --git a/kernel/params.c b/kernel/params.c index f27c992a462..b077f1b045d 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -637,14 +637,14 @@ static void __init param_sysfs_builtin(void) dot = strchr(kp->name, '.'); if (!dot) { - DEBUGP("couldn't find period in first %d characters " - "of %s\n", MODULE_NAME_LEN, kp->name); - continue; + /* This happens for core_param() */ + strcpy(modname, "kernel"); + name_len = 0; + } else { + name_len = dot - kp->name + 1; + strlcpy(modname, kp->name, name_len); } - name_len = dot - kp->name; - strncpy(modname, kp->name, name_len); - modname[name_len] = '\0'; - kernel_add_sysfs_param(modname, kp, name_len+1); + kernel_add_sysfs_param(modname, kp, name_len); } } -- cgit v1.2.3-70-g09d2