From cc4860773f6f8f35a178bc9615ec52c3fbc86ca4 Mon Sep 17 00:00:00 2001 From: Ben Hutchings Date: Thu, 28 Apr 2016 09:24:05 +0930 Subject: Documentation/module-signing.txt: Note need for version info if reusing a key commit b8612e517c3c9809e1200b72c474dbfd969e5a83 upstream. Signing a module should only make it trusted by the specific kernel it was built for, not anything else. If a module signing key is used for multiple ABI-incompatible kernels, the modules need to include enough version information to distinguish them. Signed-off-by: Ben Hutchings Signed-off-by: Rusty Russell Signed-off-by: Greg Kroah-Hartman --- Documentation/module-signing.txt | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/Documentation/module-signing.txt b/Documentation/module-signing.txt index a78bf1ffa68c..39b7f612c418 100644 --- a/Documentation/module-signing.txt +++ b/Documentation/module-signing.txt @@ -271,3 +271,9 @@ Since the private key is used to sign modules, viruses and malware could use the private key to sign modules and compromise the operating system. The private key must be either destroyed or moved to a secure location and not kept in the root node of the kernel source tree. + +If you use the same private key to sign modules for multiple kernel +configurations, you must ensure that the module version information is +sufficient to prevent loading a module into a different kernel. Either +set CONFIG_MODVERSIONS=y or ensure that each configuration has a different +kernel release string by changing EXTRAVERSION or CONFIG_LOCALVERSION. -- cgit v1.2.3