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Subject[PATCH] allow kernel module exclusion on load
Kernel developers might find it useful for quickly getting out from some 
rough debugging scenarios.

Signed-off-by: Dan Aloni <da-x@monatomic.org>

diff --git a/init/Kconfig b/init/Kconfig
index 4e009fd..796715e 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -682,6 +682,17 @@ config KMOD
runs modprobe with the appropriate arguments, thereby
loading the module if it is available. If unsure, say Y.

+config MODULE_EXCLUSION
+ bool "Refuse loading of modules with certain names"
+ depends on MODULES && DEBUG_KERNEL
+ help
+ During kernel module development and debugging you might come
+ into a situation where one of your kernel modules crashes the
+ kernel on boot. This option lets you specify in the kernel
+ command line (via exclude-modules=) a comma-separated list
+ of kernel modules that the kernel will refuse to load based
+ on their names.
+
config STOP_MACHINE
bool
default y
diff --git a/kernel/module.c b/kernel/module.c
index 9bd93de..14457dd 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1551,6 +1551,27 @@ static inline void add_kallsyms(struct module *mod,
}
#endif /* CONFIG_KALLSYMS */

+#ifdef CONFIG_MODULE_EXCLUSION
+
+static char exclusion_names[0x100];
+static int __init module_exclusion_setup(char *str)
+{
+ snprintf(exclusion_names, sizeof(exclusion_names), ",%s,", str);
+ return 1;
+}
+__setup("exclude-modules=", module_exclusion_setup);
+
+static int is_module_excluded(const char *name)
+{
+ char lookup_str[MODULE_NAME_LEN+3];
+ snprintf(lookup_str, sizeof(lookup_str), ",%s,", name);
+ return strstr(exclusion_names, lookup_str) != NULL;
+}
+
+#else
+static inline int is_module_excluded(const char *name) {return 0;}
+#endif
+
/* Allocate and load the module: note that size of section 0 is always
zero, and we rely on this for optional sections. */
static struct module *load_module(void __user *umod,
@@ -1714,6 +1735,11 @@ static struct module *load_module(void __user *umod,
goto free_hdr;
}

+ if (is_module_excluded(mod->name)) {
+ err = -EACCES;
+ goto free_mod;
+ }
+
if (find_module(mod->name)) {
err = -EEXIST;
goto free_mod;

--
Dan Aloni
XIV LTD, http://www.xivstorage.com
da-x (at) monatomic.org, dan (at) xiv.co.il
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