| 1 | |
| 2 | *
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| 3 | * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
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| 4 | * Written by David Howells ([email protected])
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| 5 | *
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| 6 | * This program is free software; you can redistribute it and/or
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| 7 | * modify it under the terms of the GNU General Public Licence
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| 8 | * as published by the Free Software Foundation; either version
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| 9 | * 2 of the Licence, or (at your option) any later version.
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| 10 |
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| 11 |
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| 12 | #include <linux/kernel.h>
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| 13 | #include <keys/system_keyring.h>
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| 14 | #include <crypto/public_key.h>
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| 15 | #include "module-internal.h"
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| 16 |
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| 17 | |
| 18 | * Module signature information block.
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| 19 | *
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| 20 | * The constituents of the signature section are, in order:
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| 21 | *
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| 22 | * - Signer's name
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| 23 | * - Key identifier
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| 24 | * - Signature data
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| 25 | * - Information block
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| 26 |
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| 27 | struct module_signature {
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| 28 | u8 algo;
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| 29 | u8 hash;
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| 30 | u8 id_type;
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| 31 | u8 signer_len;
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| 32 | u8 key_id_len;
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| 33 | u8 __pad[3];
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| 34 | __be32 sig_len;
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| 35 | };
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| 36 |
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| 37 | |
| 38 | * Verify the signature on a module.
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| 39 |
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| 40 | int mod_verify_sig(const void *mod, unsigned long *_modlen)
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| 41 | {
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| 42 | struct module_signature ms;
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| 43 | size_t modlen = *_modlen, sig_len;
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| 44 |
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| 45 | pr_devel("==>%s(,%zu)\n", __func__, modlen);
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| 46 |
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| 47 | if (modlen <= sizeof(ms))
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| 48 | return -EBADMSG;
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| 49 |
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| 50 | memcpy(&ms, mod + (modlen - sizeof(ms)), sizeof(ms));
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| 51 | modlen -= sizeof(ms);
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| 52 |
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| 53 | sig_len = be32_to_cpu(ms.sig_len);
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| 54 | if (sig_len >= modlen)
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| 55 | return -EBADMSG;
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| 56 | modlen -= sig_len;
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| 57 | *_modlen = modlen;
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| 58 |
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| 59 | if (ms.id_type != PKEY_ID_PKCS7) {
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| 60 | pr_err("Module is not signed with expected PKCS#7 message\n");
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| 61 | return -ENOPKG;
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| 62 | }
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| 63 |
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| 64 | if (ms.algo != 0 ||
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| 65 | ms.hash != 0 ||
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| 66 | ms.signer_len != 0 ||
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| 67 | ms.key_id_len != 0 ||
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| 68 | ms.__pad[0] != 0 ||
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| 69 | ms.__pad[1] != 0 ||
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| 70 | ms.__pad[2] != 0) {
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| 71 | pr_err("PKCS#7 signature info has unexpected non-zero params\n");
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| 72 | return -EBADMSG;
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| 73 | }
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| 74 |
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| 75 | return system_verify_data(mod, modlen, mod + modlen, sig_len,
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| 76 | VERIFYING_MODULE_SIGNATURE);
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| 77 | }
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