diff options
author | David Howells <dhowells@redhat.com> | 2012-09-26 10:09:51 +0100 |
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committer | Rusty Russell <rusty@rustcorp.com.au> | 2012-10-10 20:01:22 +1030 |
commit | 631cc66eb9eaa7296e303197ff1eb0f55e32b61d (patch) | |
tree | 631c962060a776a16ec35c477e99d4ef87c8db24 /kernel/modsign_pubkey.c | |
parent | d441108c6f77541bb66fcd5b3389415b4c232008 (diff) | |
download | linux-631cc66eb9eaa7296e303197ff1eb0f55e32b61d.tar.bz2 |
MODSIGN: Provide module signing public keys to the kernel
Include a PGP keyring containing the public keys required to perform module
verification in the kernel image during build and create a special keyring
during boot which is then populated with keys of crypto type holding the public
keys found in the PGP keyring.
These can be seen by root:
[root@andromeda ~]# cat /proc/keys
07ad4ee0 I----- 1 perm 3f010000 0 0 crypto modsign.0: RSA 87b9b3bd []
15c7f8c3 I----- 1 perm 1f030000 0 0 keyring .module_sign: 1/4
...
It is probably worth permitting root to invalidate these keys, resulting in
their removal and preventing further modules from being loaded with that key.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'kernel/modsign_pubkey.c')
-rw-r--r-- | kernel/modsign_pubkey.c | 113 |
1 files changed, 113 insertions, 0 deletions
diff --git a/kernel/modsign_pubkey.c b/kernel/modsign_pubkey.c new file mode 100644 index 000000000000..4646eb2c3820 --- /dev/null +++ b/kernel/modsign_pubkey.c @@ -0,0 +1,113 @@ +/* Public keys for module signature verification + * + * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + */ + +#include <linux/kernel.h> +#include <linux/sched.h> +#include <linux/cred.h> +#include <linux/err.h> +#include <keys/asymmetric-type.h> +#include "module-internal.h" + +struct key *modsign_keyring; + +extern __initdata const u8 modsign_certificate_list[]; +extern __initdata const u8 modsign_certificate_list_end[]; +asm(".section .init.data,\"aw\"\n" + "modsign_certificate_list:\n" + ".incbin \"signing_key.x509\"\n" + ".incbin \"extra_certificates\"\n" + "modsign_certificate_list_end:" + ); + +/* + * We need to make sure ccache doesn't cache the .o file as it doesn't notice + * if modsign.pub changes. + */ +static __initdata const char annoy_ccache[] = __TIME__ "foo"; + +/* + * Load the compiled-in keys + */ +static __init int module_verify_init(void) +{ + pr_notice("Initialise module verification\n"); + + modsign_keyring = key_alloc(&key_type_keyring, ".module_sign", + KUIDT_INIT(0), KGIDT_INIT(0), + current_cred(), + (KEY_POS_ALL & ~KEY_POS_SETATTR) | + KEY_USR_VIEW | KEY_USR_READ, + KEY_ALLOC_NOT_IN_QUOTA); + if (IS_ERR(modsign_keyring)) + panic("Can't allocate module signing keyring\n"); + + if (key_instantiate_and_link(modsign_keyring, NULL, 0, NULL, NULL) < 0) + panic("Can't instantiate module signing keyring\n"); + + return 0; +} + +/* + * Must be initialised before we try and load the keys into the keyring. + */ +device_initcall(module_verify_init); + +/* + * Load the compiled-in keys + */ +static __init int load_module_signing_keys(void) +{ + key_ref_t key; + const u8 *p, *end; + size_t plen; + + pr_notice("Loading module verification certificates\n"); + + end = modsign_certificate_list_end; + p = modsign_certificate_list; + while (p < end) { + /* Each cert begins with an ASN.1 SEQUENCE tag and must be more + * than 256 bytes in size. + */ + if (end - p < 4) + goto dodgy_cert; + if (p[0] != 0x30 && + p[1] != 0x82) + goto dodgy_cert; + plen = (p[2] << 8) | p[3]; + plen += 4; + if (plen > end - p) + goto dodgy_cert; + + key = key_create_or_update(make_key_ref(modsign_keyring, 1), + "asymmetric", + NULL, + p, + plen, + (KEY_POS_ALL & ~KEY_POS_SETATTR) | + KEY_USR_VIEW, + KEY_ALLOC_NOT_IN_QUOTA); + if (IS_ERR(key)) + pr_err("MODSIGN: Problem loading in-kernel X.509 certificate (%ld)\n", + PTR_ERR(key)); + else + pr_notice("MODSIGN: Loaded cert '%s'\n", + key_ref_to_ptr(key)->description); + p += plen; + } + + return 0; + +dodgy_cert: + pr_err("MODSIGN: Problem parsing in-kernel X.509 certificate list\n"); + return 0; +} +late_initcall(load_module_signing_keys); |