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Fix occasional EBADMSG from signed modules. (rhbz 804345)

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This commit is contained in:
Dave Jones 2012-03-22 17:28:30 -04:00
parent 45f4e434f4
commit 6d70ea92cc
2 changed files with 34 additions and 0 deletions
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3
kernel.spec
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@ -2336,6 +2336,9 @@ fi
# ||----w |
# || ||
%changelog
* Thu Mar 22 2012 Dave Jones <davej@redhat.com>
- Fix occasional EBADMSG from signed modules. (rhbz 804345)
* Thu Mar 22 2012 Dave Jones <davej@redhat.com> 3.4.0-0.rc0.git1.2
- Fix dentry hash collisions that prevented boot with selinux enabled (rhbz 805371)

31
modsign-20111207.patch
View File

@ -7359,3 +7359,34 @@ index 5e77c2a..e40f9b68 100644
--
1.7.9.1
diff --git a/security/keys/crypto_rsa.c b/security/keys/crypto_rsa.c
--- a/security/keys/crypto_rsa.c
--- b/security/keys/crypto_rsa.c
@@ -219,15 +219,24 @@
kenter("");
/* (1) Check the signature size against the public key modulus size */
- k = (mpi_get_nbits(key->rsa.n) + 7) / 8;
+ k = mpi_get_nbits(key->rsa.n);
+ tsize = mpi_get_nbits(sig->rsa.s);
- tsize = (mpi_get_nbits(sig->rsa.s) + 7) / 8;
+ /* According to RFC 4880 sec 3.2, length of MPI is computed starting
+ * from most significant bit.
+ * So the RFC 3447 sec 8.2.2 size check must be relaxed to conform
+ * with shorter signatures.
+ * Fail here only if signature length is longer than modulus size.
+ */
pr_devel("step 1: k=%zu size(S)=%zu\n", k, tsize);
- if (tsize != k) {
+ if (k < tsize) {
ret = -EBADMSG;
goto error;
}
+ /* Round up to octets */
+ k = (k + 7) / 8;
+
/* (2b) Apply the RSAVP1 verification primitive to the public key */
ret = RSAVP1(key, sig->rsa.s, &m);
if (ret < 0)