drbd: Allow to change data-integrity-alg on the fly

The main purpose of this is to allow to turn data integrity checking on
and off on demand without causing interruptions.

Implemented by allocating tconn->peer_integrity_tfm only when receiving
a P_PROTOCOL message.  l accesses to tconn->peer_integrity_tf happen in
worker context, and no further synchronization is necessary.

On the sender side, tconn->integrity_tfm is modified under
tconn->data.mutex, and a P_PROTOCOL message is sent whenever.  All
accesses to tconn->integrity_tfm already happen under this mutex.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 3cb2af6..a5c9b38 100644 (file)
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -1433,8 +1433,8 @@ static int _drbd_send_ack(struct drbd_conf *mdev, enum drbd_packet cmd,
 void drbd_send_ack_dp(struct drbd_conf *mdev, enum drbd_packet cmd,
                      struct p_data *dp, int data_size)
 {
-       data_size -= (mdev->tconn->agreed_pro_version >= 87 && mdev->tconn->peer_integrity_tfm) ?
-               crypto_hash_digestsize(mdev->tconn->peer_integrity_tfm) : 0;
+       if (mdev->tconn->peer_integrity_tfm)
+               data_size -= crypto_hash_digestsize(mdev->tconn->peer_integrity_tfm);
        _drbd_send_ack(mdev, cmd, dp->sector, cpu_to_be32(data_size),
                       dp->block_id);
 }

diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index dc5824b..17c0cda 100644 (file)
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -1793,7 +1793,6 @@ struct crypto {
        struct crypto_hash *csums_tfm;
        struct crypto_hash *cram_hmac_tfm;
        struct crypto_hash *integrity_tfm;
-       struct crypto_hash *peer_integrity_tfm;
        void *int_dig_in;
        void *int_dig_vv;
 };
@@ -1832,10 +1831,6 @@ alloc_crypto(struct crypto *crypto, struct net_conf *new_conf)
                       ERR_INTEGRITY_ALG);
        if (rv != NO_ERROR)
                return rv;
-       rv = alloc_hash(&crypto->peer_integrity_tfm, new_conf->integrity_alg,
-                      ERR_INTEGRITY_ALG);
-       if (rv != NO_ERROR)
-               return rv;
        if (new_conf->cram_hmac_alg[0] != 0) {
                snprintf(hmac_name, CRYPTO_MAX_ALG_NAME, "hmac(%s)",
                         new_conf->cram_hmac_alg);
@@ -1862,7 +1857,6 @@ static void free_crypto(struct crypto *crypto)
        kfree(crypto->int_dig_vv);
        crypto_free_hash(crypto->cram_hmac_tfm);
        crypto_free_hash(crypto->integrity_tfm);
-       crypto_free_hash(crypto->peer_integrity_tfm);
        crypto_free_hash(crypto->csums_tfm);
        crypto_free_hash(crypto->verify_tfm);
 }
@@ -1876,6 +1870,7 @@ int drbd_adm_net_opts(struct sk_buff *skb, struct genl_info *info)
        int ovr; /* online verify running */
        int rsr; /* re-sync running */
        struct crypto crypto = { };
+       bool change_integrity_alg;
 
        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_CONN);
        if (!adm_ctx.reply_skb)
@@ -1893,6 +1888,7 @@ int drbd_adm_net_opts(struct sk_buff *skb, struct genl_info *info)
 
        conn_reconfig_start(tconn);
 
+       mutex_lock(&tconn->data.mutex);
        mutex_lock(&tconn->net_conf_update);
        old_conf = tconn->net_conf;
 
@@ -1931,6 +1927,9 @@ int drbd_adm_net_opts(struct sk_buff *skb, struct genl_info *info)
                goto fail;
        }
 
+       change_integrity_alg = strcmp(old_conf->integrity_alg,
+                                     new_conf->integrity_alg);
+
        retcode = alloc_crypto(&crypto, new_conf);
        if (retcode != NO_ERROR)
                goto fail;
@@ -1948,21 +1947,24 @@ int drbd_adm_net_opts(struct sk_buff *skb, struct genl_info *info)
                crypto.verify_tfm = NULL;
        }
 
-       /* FIXME can not assign these so bluntly while we have ongoing IO */
        kfree(tconn->int_dig_in);
        tconn->int_dig_in = crypto.int_dig_in;
        kfree(tconn->int_dig_vv);
        tconn->int_dig_vv = crypto.int_dig_vv;
        crypto_free_hash(tconn->integrity_tfm);
        tconn->integrity_tfm = crypto.integrity_tfm;
-       crypto_free_hash(tconn->peer_integrity_tfm);
-       tconn->peer_integrity_tfm = crypto.peer_integrity_tfm;
+       if (change_integrity_alg) {
+               /* Do this without trying to take tconn->data.mutex again.  */
+               if (__drbd_send_protocol(tconn))
+                       goto fail;
+       }
 
        /* FIXME Changing cram_hmac while the connection is established is useless */
        crypto_free_hash(tconn->cram_hmac_tfm);
        tconn->cram_hmac_tfm = crypto.cram_hmac_tfm;
 
        mutex_unlock(&tconn->net_conf_update);
+       mutex_unlock(&tconn->data.mutex);
        synchronize_rcu();
        kfree(old_conf);
 
@@ -1973,6 +1975,7 @@ int drbd_adm_net_opts(struct sk_buff *skb, struct genl_info *info)
 
  fail:
        mutex_unlock(&tconn->net_conf_update);
+       mutex_unlock(&tconn->data.mutex);
        free_crypto(&crypto);
        kfree(new_conf);
  done:
@@ -2081,7 +2084,6 @@ int drbd_adm_connect(struct sk_buff *skb, struct genl_info *info)
        tconn->int_dig_vv = crypto.int_dig_vv;
        tconn->cram_hmac_tfm = crypto.cram_hmac_tfm;
        tconn->integrity_tfm = crypto.integrity_tfm;
-       tconn->peer_integrity_tfm = crypto.peer_integrity_tfm;
        tconn->csums_tfm = crypto.csums_tfm;
        tconn->verify_tfm = crypto.verify_tfm;
 

diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 30b6556..9c8bcce 100644 (file)
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -1384,10 +1384,9 @@ read_in_block(struct drbd_conf *mdev, u64 id, sector_t sector,
        void *dig_vv = mdev->tconn->int_dig_vv;
        unsigned long *data;
 
-       dgs = (mdev->tconn->agreed_pro_version >= 87 && mdev->tconn->peer_integrity_tfm) ?
-               crypto_hash_digestsize(mdev->tconn->peer_integrity_tfm) : 0;
-
-       if (dgs) {
+       dgs = 0;
+       if (mdev->tconn->peer_integrity_tfm) {
+               dgs = crypto_hash_digestsize(mdev->tconn->peer_integrity_tfm);
                /*
                 * FIXME: Receive the incoming digest into the receive buffer
                 *        here, together with its struct p_data?
@@ -1395,10 +1394,9 @@ read_in_block(struct drbd_conf *mdev, u64 id, sector_t sector,
                err = drbd_recv_all_warn(mdev->tconn, dig_in, dgs);
                if (err)
                        return NULL;
+               data_size -= dgs;
        }
 
-       data_size -= dgs;
-
        if (!expect(data_size != 0))
                return NULL;
        if (!expect(IS_ALIGNED(data_size, 512)))
@@ -1491,17 +1489,15 @@ static int recv_dless_read(struct drbd_conf *mdev, struct drbd_request *req,
        void *dig_in = mdev->tconn->int_dig_in;
        void *dig_vv = mdev->tconn->int_dig_vv;
 
-       dgs = (mdev->tconn->agreed_pro_version >= 87 && mdev->tconn->peer_integrity_tfm) ?
-               crypto_hash_digestsize(mdev->tconn->peer_integrity_tfm) : 0;
-
-       if (dgs) {
+       dgs = 0;
+       if (mdev->tconn->peer_integrity_tfm) {
+               dgs = crypto_hash_digestsize(mdev->tconn->peer_integrity_tfm);
                err = drbd_recv_all_warn(mdev->tconn, dig_in, dgs);
                if (err)
                        return err;
+               data_size -= dgs;
        }
 
-       data_size -= dgs;
-
        /* optimistically update recv_cnt.  if receiving fails below,
         * we disconnect anyways, and counters will be reset. */
        mdev->recv_cnt += data_size>>9;
@@ -2997,7 +2993,6 @@ static int receive_protocol(struct drbd_tconn *tconn, struct packet_info *pi)
        struct p_protocol *p = pi->data;
        int p_proto, p_after_sb_0p, p_after_sb_1p, p_after_sb_2p;
        int p_want_lose, p_two_primaries, cf;
-       char p_integrity_alg[SHARED_SECRET_MAX] = "";
        struct net_conf *nc;
 
        p_proto         = be32_to_cpu(p->protocol);
@@ -3009,15 +3004,30 @@ static int receive_protocol(struct drbd_tconn *tconn, struct packet_info *pi)
        p_want_lose = cf & CF_WANT_LOSE;
 
        if (tconn->agreed_pro_version >= 87) {
+               char integrity_alg[SHARED_SECRET_MAX];
+               struct crypto_hash *tfm = NULL;
                int err;
 
-               if (pi->size > sizeof(p_integrity_alg))
+               if (pi->size > sizeof(integrity_alg))
                        return -EIO;
-               err = drbd_recv_all(tconn, p_integrity_alg, pi->size);
+               err = drbd_recv_all(tconn, integrity_alg, pi->size);
                if (err)
                        return err;
+               integrity_alg[SHARED_SECRET_MAX-1] = 0;
 
-               p_integrity_alg[SHARED_SECRET_MAX-1] = 0;
+               if (integrity_alg[0]) {
+                       tfm = crypto_alloc_hash(integrity_alg, 0, CRYPTO_ALG_ASYNC);
+                       if (!tfm) {
+                               conn_err(tconn, "peer data-integrity-alg %s not supported\n",
+                                        integrity_alg);
+                               goto disconnect;
+                       }
+                       conn_info(tconn, "peer data-integrity-alg: %s\n", integrity_alg);
+               }
+
+               if (tconn->peer_integrity_tfm)
+                       crypto_free_hash(tconn->peer_integrity_tfm);
+               tconn->peer_integrity_tfm = tfm;
        }
 
        clear_bit(CONN_DRY_RUN, &tconn->flags);
@@ -3058,20 +3068,8 @@ static int receive_protocol(struct drbd_tconn *tconn, struct packet_info *pi)
                goto disconnect_rcu_unlock;
        }
 
-       if (tconn->agreed_pro_version >= 87) {
-               if (strcmp(p_integrity_alg, nc->integrity_alg)) {
-                       conn_err(tconn, "incompatible setting of the data-integrity-alg\n");
-                       goto disconnect;
-               }
-       }
-
        rcu_read_unlock();
 
-       if (tconn->agreed_pro_version >= 87) {
-               conn_info(tconn, "data-integrity-alg: %s\n",
-                         nc->integrity_alg[0] ? nc->integrity_alg : (unsigned char *)"<not-used>");
-       }
-
        return 0;
 
 disconnect_rcu_unlock: