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5 Commits
| Author | SHA1 | Message | Date | |
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Tuong Lien
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23700da29b |
tipc: add automatic rekeying for encryption key
Rekeying is required for security since a key is less secure when using for a long time. Also, key will be detached when its nonce value (or seqno ...) is exhausted. We now make the rekeying process automatic and configurable by user. Basically, TIPC will at a specific interval generate a new key by using the kernel 'Random Number Generator' cipher, then attach it as the node TX key and securely distribute to others in the cluster as RX keys (- the key exchange). The automatic key switching will then take over, and make the new key active shortly. Afterwards, the traffic from this node will be encrypted with the new session key. The same can happen in peer nodes but not necessarily at the same time. For simplicity, the automatically generated key will be initiated as a per node key. It is not too hard to also support a cluster key rekeying (e.g. a given node will generate a unique cluster key and update to the others in the cluster...), but that doesn't bring much benefit, while a per-node key is even more secure. We also enable user to force a rekeying or change the rekeying interval via netlink, the new 'set key' command option: 'TIPC_NLA_NODE_REKEYING' is added for these purposes as follows: - A value >= 1 will be set as the rekeying interval (in minutes); - A value of 0 will disable the rekeying; - A value of 'TIPC_REKEYING_NOW' (~0) will force an immediate rekeying; The default rekeying interval is (60 * 24) minutes i.e. done every day. There isn't any restriction for the value but user shouldn't set it too small or too large which results in an "ineffective" rekeying (thats ok for testing though). Acked-by: Jon Maloy <jmaloy@redhat.com> Signed-off-by: Tuong Lien <tuong.t.lien@dektech.com.au> Signed-off-by: David S. Miller <davem@davemloft.net> |
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Tuong Lien
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1ef6f7c939 |
tipc: add automatic session key exchange
With support from the master key option in the previous commit, it becomes easy to make frequent updates/exchanges of session keys between authenticated cluster nodes. Basically, there are two situations where the key exchange will take in place: - When a new node joins the cluster (with the master key), it will need to get its peer's TX key, so that be able to decrypt further messages from that peer. - When a new session key is generated (by either user manual setting or later automatic rekeying feature), the key will be distributed to all peer nodes in the cluster. A key to be exchanged is encapsulated in the data part of a 'MSG_CRYPTO /KEY_DISTR_MSG' TIPC v2 message, then xmit-ed as usual and encrypted by using the master key before sending out. Upon receipt of the message it will be decrypted in the same way as regular messages, then attached as the sender's RX key in the receiver node. In this way, the key exchange is reliable by the link layer, as well as security, integrity and authenticity by the crypto layer. Also, the forward security will be easily achieved by user changing the master key actively but this should not be required very frequently. The key exchange feature is independent on the presence of a master key Note however that the master key still is needed for new nodes to be able to join the cluster. It is also optional, and can be turned off/on via the sysfs: 'net/tipc/key_exchange_enabled' [default 1: enabled]. Backward compatibility is guaranteed because for nodes that do not have master key support, key exchange using master key ie. tx_key = 0 if any will be shortly discarded at the message validation step. In other words, the key exchange feature will be automatically disabled to those nodes. v2: fix the "implicit declaration of function 'tipc_crypto_key_flush'" error in node.c. The function only exists when built with the TIPC "CONFIG_TIPC_CRYPTO" option. v3: use 'info->extack' for a message emitted due to netlink operations instead (- David's comment). Reported-by: kernel test robot <lkp@intel.com> Acked-by: Jon Maloy <jmaloy@redhat.com> Signed-off-by: Tuong Lien <tuong.t.lien@dektech.com.au> Signed-off-by: David S. Miller <davem@davemloft.net> |
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Tuong Lien
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daef1ee379 |
tipc: introduce encryption master key
In addition to the supported cluster & per-node encryption keys for the en/decryption of TIPC messages, we now introduce one option for user to set a cluster key as 'master key', which is simply a symmetric key like the former but has a longer life cycle. It has two purposes: - Authentication of new member nodes in the cluster. New nodes, having no knowledge of current session keys in the cluster will still be able to join the cluster as long as they know the master key. This is because all neighbor discovery (LINK_CONFIG) messages must be encrypted with this key. - Encryption of session encryption keys during automatic exchange and update of those.This is a feature we will introduce in a later commit in this series. We insert the new key into the currently unused slot 0 in the key array and start using it immediately once the user has set it. After joining, a node only knowing the master key should be fully communicable to existing nodes in the cluster, although those nodes may have their own session keys activated (i.e. not the master one). To support this, we define a 'grace period', starting from the time a node itself reports having no RX keys, so the existing nodes will use the master key for encryption instead. The grace period can be extended but will automatically stop after e.g. 5 seconds without a new report. This is also the basis for later key exchanging feature as the new node will be impossible to decrypt anything without the support from master key. For user to set a master key, we define a new netlink flag - 'TIPC_NLA_NODE_KEY_MASTER', so it can be added to the current 'set key' netlink command to specify the setting key to be a master key. Above all, the traditional cluster/per-node key mechanism is guaranteed to work when user comes not to use this master key option. This is also compatible to legacy nodes without the feature supported. Even this master key can be updated without any interruption of cluster connectivity but is so is needed, this has to be coordinated and set by the user. Acked-by: Jon Maloy <jmaloy@redhat.com> Signed-off-by: Tuong Lien <tuong.t.lien@dektech.com.au> Signed-off-by: David S. Miller <davem@davemloft.net> |
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Tuong Lien
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f779bf7922 |
tipc: optimize key switching time and logic
We reduce the lasting time for a pending TX key to be active as well as
for a passive RX key to be freed which generally helps speed up the key
switching. It is not expected to be too fast but should not be too slow
either. Also the key handling logic is simplified that a pending RX key
will be removed automatically if it is found not working after a number
of times; the probing for a pending TX key is now carried on a specific
message user ('LINK_PROTOCOL' or 'LINK_CONFIG') which is more efficient
than using a timer on broadcast messages, the timer is reserved for use
later as needed.
The kernel logs or 'pr***()' are now made as clear as possible to user.
Some prints are added, removed or changed to the debug-level. The
'TIPC_CRYPTO_DEBUG' definition is removed, and the 'pr_debug()' is used
instead which will be much helpful in runtime.
Besides we also optimize the code in some other places as a preparation
for later commits.
v2: silent more kernel logs, also use 'info->extack' for a message
emitted due to netlink operations instead (- David's comments).
Acked-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: Tuong Lien <tuong.t.lien@dektech.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Tuong Lien
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fc1b6d6de2 |
tipc: introduce TIPC encryption & authentication
This commit offers an option to encrypt and authenticate all messaging,
including the neighbor discovery messages. The currently most advanced
algorithm supported is the AEAD AES-GCM (like IPSec or TLS). All
encryption/decryption is done at the bearer layer, just before leaving
or after entering TIPC.
Supported features:
- Encryption & authentication of all TIPC messages (header + data);
- Two symmetric-key modes: Cluster and Per-node;
- Automatic key switching;
- Key-expired revoking (sequence number wrapped);
- Lock-free encryption/decryption (RCU);
- Asynchronous crypto, Intel AES-NI supported;
- Multiple cipher transforms;
- Logs & statistics;
Two key modes:
- Cluster key mode: One single key is used for both TX & RX in all
nodes in the cluster.
- Per-node key mode: Each nodes in the cluster has one specific TX key.
For RX, a node requires its peers' TX key to be able to decrypt the
messages from those peers.
Key setting from user-space is performed via netlink by a user program
(e.g. the iproute2 'tipc' tool).
Internal key state machine:
Attach Align(RX)
+-+ +-+
| V | V
+---------+ Attach +---------+
| IDLE |---------------->| PENDING |(user = 0)
+---------+ +---------+
A A Switch| A
| | | |
| | Free(switch/revoked) | |
(Free)| +----------------------+ | |Timeout
| (TX) | | |(RX)
| | | |
| | v |
+---------+ Switch +---------+
| PASSIVE |<----------------| ACTIVE |
+---------+ (RX) +---------+
(user = 1) (user >= 1)
The number of TFMs is 10 by default and can be changed via the procfs
'net/tipc/max_tfms'. At this moment, as for simplicity, this file is
also used to print the crypto statistics at runtime:
echo 0xfff1 > /proc/sys/net/tipc/max_tfms
The patch defines a new TIPC version (v7) for the encryption message (-
backward compatibility as well). The message is basically encapsulated
as follows:
+----------------------------------------------------------+
| TIPCv7 encryption | Original TIPCv2 | Authentication |
| header | packet (encrypted) | Tag |
+----------------------------------------------------------+
The throughput is about ~40% for small messages (compared with non-
encryption) and ~9% for large messages. With the support from hardware
crypto i.e. the Intel AES-NI CPU instructions, the throughput increases
upto ~85% for small messages and ~55% for large messages.
By default, the new feature is inactive (i.e. no encryption) until user
sets a key for TIPC. There is however also a new option - "TIPC_CRYPTO"
in the kernel configuration to enable/disable the new code when needed.
MAINTAINERS | add two new files 'crypto.h' & 'crypto.c' in tipc
Acked-by: Ying Xue <ying.xue@windreiver.com>
Acked-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: Tuong Lien <tuong.t.lien@dektech.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
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