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authorBen Hutchings <ben@decadent.org.uk>2016-04-28 09:24:05 +0930
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-08-20 18:09:27 +0200
commitcc4860773f6f8f35a178bc9615ec52c3fbc86ca4 (patch)
parentbc2318cc76df4fb80c3b5b9ec0e1633627dabb54 (diff)
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 <ben@decadent.org.uk> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 6 insertions, 0 deletions
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.