diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/Makefile | 1 | ||||
| -rw-r--r-- | kernel/module-internal.h | 13 | ||||
| -rw-r--r-- | kernel/module.c | 93 | ||||
| -rw-r--r-- | kernel/module_signing.c | 23 |
4 files changed, 129 insertions, 1 deletions
diff --git a/kernel/Makefile b/kernel/Makefile index c0cc67ad764c..08ba8a6abd1c 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -55,6 +55,7 @@ obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o obj-$(CONFIG_PROVE_LOCKING) += spinlock.o obj-$(CONFIG_UID16) += uid16.o obj-$(CONFIG_MODULES) += module.o +obj-$(CONFIG_MODULE_SIG) += module_signing.o obj-$(CONFIG_KALLSYMS) += kallsyms.o obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o obj-$(CONFIG_KEXEC) += kexec.o diff --git a/kernel/module-internal.h b/kernel/module-internal.h new file mode 100644 index 000000000000..033c17fd70ef --- /dev/null +++ b/kernel/module-internal.h @@ -0,0 +1,13 @@ +/* Module internals + * + * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + */ + +extern int mod_verify_sig(const void *mod, unsigned long modlen, + const void *sig, unsigned long siglen); diff --git a/kernel/module.c b/kernel/module.c index 74bc19562ca3..68c564edb2c1 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -58,6 +58,7 @@ #include <linux/jump_label.h> #include <linux/pfn.h> #include <linux/bsearch.h> +#include "module-internal.h" #define CREATE_TRACE_POINTS #include <trace/events/module.h> @@ -102,6 +103,43 @@ static LIST_HEAD(modules); struct list_head *kdb_modules = &modules; /* kdb needs the list of modules */ #endif /* CONFIG_KGDB_KDB */ +#ifdef CONFIG_MODULE_SIG +#ifdef CONFIG_MODULE_SIG_FORCE +static bool sig_enforce = true; +#else +static bool sig_enforce = false; + +static int param_set_bool_enable_only(const char *val, + const struct kernel_param *kp) +{ + int err; + bool test; + struct kernel_param dummy_kp = *kp; + + dummy_kp.arg = &test; + + err = param_set_bool(val, &dummy_kp); + if (err) + return err; + + /* Don't let them unset it once it's set! */ + if (!test && sig_enforce) + return -EROFS; + + if (test) + sig_enforce = true; + return 0; +} + +static const struct kernel_param_ops param_ops_bool_enable_only = { + .set = param_set_bool_enable_only, + .get = param_get_bool, +}; +#define param_check_bool_enable_only param_check_bool + +module_param(sig_enforce, bool_enable_only, 0644); +#endif /* !CONFIG_MODULE_SIG_FORCE */ +#endif /* CONFIG_MODULE_SIG */ /* Block module loading/unloading? */ int modules_disabled = 0; @@ -136,6 +174,7 @@ struct load_info { unsigned long symoffs, stroffs; struct _ddebug *debug; unsigned int num_debug; + bool sig_ok; struct { unsigned int sym, str, mod, vers, info, pcpu; } index; @@ -2379,7 +2418,49 @@ static inline void kmemleak_load_module(const struct module *mod, } #endif -/* Sets info->hdr and info->len. */ +#ifdef CONFIG_MODULE_SIG +static int module_sig_check(struct load_info *info, + const void *mod, unsigned long *len) +{ + int err = -ENOKEY; + const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; + const void *p = mod, *end = mod + *len; + + /* Poor man's memmem. */ + while ((p = memchr(p, MODULE_SIG_STRING[0], end - p))) { + if (p + markerlen > end) + break; + + if (memcmp(p, MODULE_SIG_STRING, markerlen) == 0) { + const void *sig = p + markerlen; + /* Truncate module up to signature. */ + *len = p - mod; + err = mod_verify_sig(mod, *len, sig, end - sig); + break; + } + p++; + } + + if (!err) { + info->sig_ok = true; + return 0; + } + + /* Not having a signature is only an error if we're strict. */ + if (err == -ENOKEY && !sig_enforce) + err = 0; + + return err; +} +#else /* !CONFIG_MODULE_SIG */ +static int module_sig_check(struct load_info *info, + void *mod, unsigned long *len) +{ + return 0; +} +#endif /* !CONFIG_MODULE_SIG */ + +/* Sets info->hdr, info->len and info->sig_ok. */ static int copy_and_check(struct load_info *info, const void __user *umod, unsigned long len, const char __user *uargs) @@ -2399,6 +2480,10 @@ static int copy_and_check(struct load_info *info, goto free_hdr; } + err = module_sig_check(info, hdr, &len); + if (err) + goto free_hdr; + /* Sanity checks against insmoding binaries or wrong arch, weird elf version */ if (memcmp(hdr->e_ident, ELFMAG, SELFMAG) != 0 @@ -2884,6 +2969,12 @@ static struct module *load_module(void __user *umod, goto free_copy; } +#ifdef CONFIG_MODULE_SIG + mod->sig_ok = info.sig_ok; + if (!mod->sig_ok) + add_taint_module(mod, TAINT_FORCED_MODULE); +#endif + /* Now module is in final location, initialize linked lists, etc. */ err = module_unload_init(mod); if (err) diff --git a/kernel/module_signing.c b/kernel/module_signing.c new file mode 100644 index 000000000000..499728aecafb --- /dev/null +++ b/kernel/module_signing.c @@ -0,0 +1,23 @@ +/* Module signature checker + * + * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + */ + +#include <linux/kernel.h> +#include <linux/err.h> +#include "module-internal.h" + +/* + * Verify the signature on a module. + */ +int mod_verify_sig(const void *mod, unsigned long modlen, + const void *sig, unsigned long siglen) +{ + return -ENOKEY; +} |