drbd: Fix a hole in the challange-response connection authentication
In the implementation as it was, the two peers sent each other a challenge, and expects the challenge hashed with the shared secret back. A attacker could simply wait for the challenge of the peer, and send the same challenge back. Then it waits for the response, and sends the same response back. Prevent this by not accepting a challenge from the peer that is the same as the challenge sent to the peer. Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com> Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com> Signed-off-by: Jens Axboe <axboe@fb.com>hifive-unleashed-5.1
parent
f9c78128f8
commit
67cca286ca
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@ -4846,6 +4846,12 @@ static int drbd_do_auth(struct drbd_connection *connection)
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goto fail;
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}
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if (pi.size < CHALLENGE_LEN) {
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drbd_err(connection, "AuthChallenge payload too small.\n");
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rv = -1;
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goto fail;
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}
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peers_ch = kmalloc(pi.size, GFP_NOIO);
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if (peers_ch == NULL) {
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drbd_err(connection, "kmalloc of peers_ch failed\n");
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@ -4859,6 +4865,12 @@ static int drbd_do_auth(struct drbd_connection *connection)
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goto fail;
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}
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if (!memcmp(my_challenge, peers_ch, CHALLENGE_LEN)) {
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drbd_err(connection, "Peer presented the same challenge!\n");
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rv = -1;
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goto fail;
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}
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resp_size = crypto_hash_digestsize(connection->cram_hmac_tfm);
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response = kmalloc(resp_size, GFP_NOIO);
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if (response == NULL) {
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