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Cryptographic algorithms may have a lifespan that is significantly shorter than Linux's, and so we need to start phasing out algorithms that are known to be broken, and are no longer fit for general use. RC4 (or arc4) is a good example here: there are a few areas where its use is still somewhat acceptable, e.g., for interoperability with legacy wifi hardware that can only use WEP or TKIP data encryption, but that should not imply that, for instance, use of RC4 based EAP-TLS by the WPA supplicant for negotiating TKIP keys is equally acceptable, or that RC4 should remain available as a general purpose cryptographic transform for all in-kernel and user space clients. Now that all in-kernel users that need to retain support have moved to the arc4 library interface, and the known users of ecb(arc4) via the socket API (iwd [0] and libell [1][2]) have been updated to switch to a local implementation, we can take the next step, and mark the ecb(arc4) skcipher as obsolete, and only provide it if the socket API is enabled in the first place, as well as provide the option to disable all algorithms that have been marked as obsolete. [0] https://git.kernel.org/pub/scm/network/wireless/iwd.git/commit/?id=1db8a85a60c64523 [1] https://git.kernel.org/pub/scm/libs/ell/ell.git/commit/?id=53482ce421b727c2 [2] https://git.kernel.org/pub/scm/libs/ell/ell.git/commit/?id=7f6a137809d42f6b Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
87 lines
2.1 KiB
C
87 lines
2.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Cryptographic API
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*
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* ARC4 Cipher Algorithm
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*
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* Jon Oberheide <jon@oberheide.org>
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*/
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#include <crypto/algapi.h>
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#include <crypto/arc4.h>
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#include <crypto/internal/skcipher.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/sched.h>
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static int crypto_arc4_setkey(struct crypto_skcipher *tfm, const u8 *in_key,
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unsigned int key_len)
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{
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struct arc4_ctx *ctx = crypto_skcipher_ctx(tfm);
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return arc4_setkey(ctx, in_key, key_len);
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}
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static int crypto_arc4_crypt(struct skcipher_request *req)
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{
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struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
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struct arc4_ctx *ctx = crypto_skcipher_ctx(tfm);
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struct skcipher_walk walk;
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int err;
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err = skcipher_walk_virt(&walk, req, false);
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while (walk.nbytes > 0) {
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arc4_crypt(ctx, walk.dst.virt.addr, walk.src.virt.addr,
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walk.nbytes);
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err = skcipher_walk_done(&walk, 0);
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}
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return err;
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}
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static int crypto_arc4_init(struct crypto_skcipher *tfm)
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{
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pr_warn_ratelimited("\"%s\" (%ld) uses obsolete ecb(arc4) skcipher\n",
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current->comm, (unsigned long)current->pid);
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return 0;
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}
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static struct skcipher_alg arc4_alg = {
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/*
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* For legacy reasons, this is named "ecb(arc4)", not "arc4".
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* Nevertheless it's actually a stream cipher, not a block cipher.
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*/
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.base.cra_name = "ecb(arc4)",
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.base.cra_driver_name = "ecb(arc4)-generic",
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.base.cra_priority = 100,
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.base.cra_blocksize = ARC4_BLOCK_SIZE,
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.base.cra_ctxsize = sizeof(struct arc4_ctx),
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.base.cra_module = THIS_MODULE,
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.min_keysize = ARC4_MIN_KEY_SIZE,
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.max_keysize = ARC4_MAX_KEY_SIZE,
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.setkey = crypto_arc4_setkey,
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.encrypt = crypto_arc4_crypt,
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.decrypt = crypto_arc4_crypt,
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.init = crypto_arc4_init,
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};
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static int __init arc4_init(void)
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{
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return crypto_register_skcipher(&arc4_alg);
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}
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static void __exit arc4_exit(void)
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{
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crypto_unregister_skcipher(&arc4_alg);
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}
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subsys_initcall(arc4_init);
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module_exit(arc4_exit);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("ARC4 Cipher Algorithm");
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MODULE_AUTHOR("Jon Oberheide <jon@oberheide.org>");
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MODULE_ALIAS_CRYPTO("ecb(arc4)");
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