[PATCH 4.7 184/186] module: Invalidate signatures on force-loaded modules
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2016-08-18 14:21:40
Also in:
lkml
4.7-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ben Hutchings <redacted> commit bca014caaa6130e57f69b5bf527967aa8ee70fdd upstream. Signing a module should only make it trusted by the specific kernel it was built for, not anything else. Loading a signed module meant for a kernel with a different ABI could have interesting effects. Therefore, treat all signatures as invalid when a module is force-loaded. Signed-off-by: Ben Hutchings <redacted> Signed-off-by: Rusty Russell <redacted> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- kernel/module.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)
--- a/kernel/module.c
+++ b/kernel/module.c@@ -2687,13 +2687,18 @@ static inline void kmemleak_load_module( #endif #ifdef CONFIG_MODULE_SIG -static int module_sig_check(struct load_info *info) +static int module_sig_check(struct load_info *info, int flags) { int err = -ENOKEY; const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; const void *mod = info->hdr; - if (info->len > markerlen && + /* + * Require flags == 0, as a module with version information + * removed is no longer the module that was signed + */ + if (flags == 0 && + info->len > markerlen && memcmp(mod + info->len - markerlen, MODULE_SIG_STRING, markerlen) == 0) { /* We truncate the module to discard the signature */ info->len -= markerlen;
@@ -2712,7 +2717,7 @@ static int module_sig_check(struct load_ return err; } #else /* !CONFIG_MODULE_SIG */ -static int module_sig_check(struct load_info *info) +static int module_sig_check(struct load_info *info, int flags) { return 0; }
@@ -3498,7 +3503,7 @@ static int load_module(struct load_info long err; char *after_dashes; - err = module_sig_check(info); + err = module_sig_check(info, flags); if (err) goto free_copy;