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2012-10-19MODSIGN: Move the magic string to the end of a module and eliminate the searchDavid Howells
Emit the magic string that indicates a module has a signature after the signature data instead of before it. This allows module_sig_check() to be made simpler and faster by the elimination of the search for the magic string. Instead we just need to do a single memcmp(). This works because at the end of the signature data there is the fixed-length signature information block. This block then falls immediately prior to the magic number. From the contents of the information block, it is trivial to calculate the size of the signature data and thus the size of the actual module data. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-19MODSIGN: perlify sign-file and merge in x509keyidDavid Howells
Turn sign-file into perl and merge in x509keyid. The latter doesn't need to be a separate script as it doesn't actually need to work out the SHA1 sum of the X.509 certificate itself, since it can get that from the X.509 certificate. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-19kbuild: Fix module signature generationLinus Torvalds
Rusty had clearly not actually tested his module signing changes that I (trustingly) applied as commit e2a666d52b48 ("kbuild: sign the modules at install time"). That commit had multiple bugs: - using "${#VARIABLE}" to get the number of characters in a shell variable may look clever, but it's locale-dependent: it returns the number of *characters*, not bytes. And we do need bytes. So don't use "${#..}" expansion, do the stupid "wc -c" thing instead (where "c" stands for "bytes", not "characters", despite the letter. - Rusty had confused "siglen" and "signerlen", and his conversion didn't set "signerlen" at all, and incorrectly set "siglen" to the size of the signer, not the size of the signature. End result: the modified sign-file script did create something that superficially *looked* like a signature, but didn't actually work at all, and would fail the signature check. Oops. Tssk, tssk, Rusty. But Rusty was definitely right that this whole thing should be rewritten in perl by somebody who has the perl-fu to do so. That is not me, though - I'm just doing an emergency fix for the shell script. Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-19kbuild: sign the modules at install timeRusty Russell
Linus deleted the old code and put signing on the install command, I fixed it to extract the keyid and signer-name within sign-file and cleaned up that script now it always signs in-place. Some enthusiast should convert sign-key to perl and pull x509keyid into it. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-10MODSIGN: Sign modules during the build processDavid Howells
If CONFIG_MODULE_SIG is set, then this patch will cause all modules files to to have signatures added. The following steps will occur: (1) The module will be linked to foo.ko.unsigned instead of foo.ko (2) The module will be stripped using both "strip -x -g" and "eu-strip" to ensure minimal size for inclusion in an initramfs. (3) The signature will be generated on the stripped module. (4) The signature will be appended to the module, along with some information about the signature and a magic string that indicates the presence of the signature. Step (3) requires private and public keys to be available. By default these are expected to be found in files: signing_key.priv signing_key.x509 in the base directory of the build. The first is the private key in PEM form and the second is the X.509 certificate in DER form as can be generated from openssl: openssl req \ -new -x509 -outform PEM -out signing_key.x509 \ -keyout signing_key.priv -nodes \ -subj "/CN=H2G2/O=Magrathea/CN=Slartibartfast" If the secret key is not found then signing will be skipped and the unsigned module from (1) will just be copied to foo.ko. If signing occurs, lines like the following will be seen: LD [M] fs/foo/foo.ko.unsigned STRIP [M] fs/foo/foo.ko.stripped SIGN [M] fs/foo/foo.ko will appear in the build log. If the signature step will be skipped and the following will be seen: LD [M] fs/foo/foo.ko.unsigned STRIP [M] fs/foo/foo.ko.stripped NO SIGN [M] fs/foo/foo.ko NOTE! After the signature step, the signed module _must_not_ be passed through strip. The unstripped, unsigned module is still available at the name on the LD [M] line. This restriction may affect packaging tools (such as rpmbuild) and initramfs composition tools. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>