@@ -212,6 +212,54 @@ remote address is already known, or the message does not require a reply.
Like the send calls, sockets will only receive responses to requests they have
sent (TO=1) and may only respond (TO=0) to requests they have received.
+``ioctl(SIOCMCTPALLOCTAG)`` and ``ioctl(SIOCMCTPDROPTAG)``
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+These tags give applications more control over MCTP message tags, by allocating
+(and dropping) tag values explicitly, rather than the kernel automatically
+allocating a per-message tag at ``sendmsg()`` time.
+
+In general, you will only need to use these ioctls if your MCTP protocol does
+not fit the usual request/response model. For example, if you need to persist
+tags across multiple requests, or a request may generate more than one response.
+In these cases, the ioctls allow you to decouple the tag allocation (and
+release) from individual message send and receive operations.
+
+Both ioctls are passed a pointer to a ``struct mctp_ioc_tag_ctl``:
+
+.. code-block:: C
+
+ struct mctp_ioc_tag_ctl {
+ mctp_eid_t peer_addr;
+ __u8 tag;
+ __u16 flags;
+ };
+
+``SIOCMCTPALLOCTAG`` allocates a tag for a specific peer, which an application
+can use in future ``sendmsg()`` calls. The application populates the
+``peer_addr`` member with the remote EID. Other fields must be zero.
+
+On return, the ``tag`` member will be populated with the allocated tag value.
+The allocated tag will have the following tag bits set:
+
+ - ``MCTP_TAG_OWNER``: it only makes sense to allocate tags if you're the tag
+ owner
+
+ - ``MCTP_TAG_PREALLOC``: to indicate to ``sendmsg()`` that this is a
+ preallocated tag.
+
+ - ... and the actual tag value, within the least-significant three bits
+ (``MCTP_TAG_MASK``). Note that zero is a valid tag value.
+
+The tag value should be used as-is for the ``smctp_tag`` member of ``struct
+sockaddr_mctp``.
+
+``SIOCMCTPDROPTAG`` releases a tag that has been previously allocated by a
+``SIOCMCTPALLOCTAG`` ioctl. The ``peer_addr`` must be the same as used for the
+allocation, and the ``tag`` value must match exactly the tag returned from the
+allocation (including the ``MCTP_TAG_OWNER`` and ``MCTP_TAG_PREALLOC`` bits).
+The ``flags`` field must be zero.
+
Kernel internals
================
@@ -126,7 +126,7 @@ struct mctp_sock {
*/
struct mctp_sk_key {
mctp_eid_t peer_addr;
- mctp_eid_t local_addr;
+ mctp_eid_t local_addr; /* MCTP_ADDR_ANY for local owned tags */
__u8 tag; /* incoming tag match; invert TO for local */
/* we hold a ref to sk when set */
@@ -163,6 +163,12 @@ struct mctp_sk_key {
*/
unsigned long dev_flow_state;
struct mctp_dev *dev;
+
+ /* a tag allocated with SIOCMCTPALLOCTAG ioctl will not expire
+ * automatically on timeout or response, instead SIOCMCTPDROPTAG
+ * is used.
+ */
+ bool manual_alloc;
};
struct mctp_skb_cb {
@@ -239,6 +245,9 @@ int mctp_local_output(struct sock *sk, struct mctp_route *rt,
struct sk_buff *skb, mctp_eid_t daddr, u8 req_tag);
void mctp_key_unref(struct mctp_sk_key *key);
+struct mctp_sk_key *mctp_alloc_local_tag(struct mctp_sock *msk,
+ mctp_eid_t daddr, mctp_eid_t saddr,
+ bool manual, u8 *tagp);
/* routing <--> device interface */
unsigned int mctp_default_net(struct net *net);
@@ -15,6 +15,7 @@ enum {
MCTP_TRACE_KEY_REPLIED,
MCTP_TRACE_KEY_INVALIDATED,
MCTP_TRACE_KEY_CLOSED,
+ MCTP_TRACE_KEY_DROPPED,
};
#endif /* __TRACE_MCTP_ENUMS */
@@ -22,6 +23,7 @@ TRACE_DEFINE_ENUM(MCTP_TRACE_KEY_TIMEOUT);
TRACE_DEFINE_ENUM(MCTP_TRACE_KEY_REPLIED);
TRACE_DEFINE_ENUM(MCTP_TRACE_KEY_INVALIDATED);
TRACE_DEFINE_ENUM(MCTP_TRACE_KEY_CLOSED);
+TRACE_DEFINE_ENUM(MCTP_TRACE_KEY_DROPPED);
TRACE_EVENT(mctp_key_acquire,
TP_PROTO(const struct mctp_sk_key *key),
@@ -66,7 +68,8 @@ TRACE_EVENT(mctp_key_release,
{ MCTP_TRACE_KEY_TIMEOUT, "timeout" },
{ MCTP_TRACE_KEY_REPLIED, "replied" },
{ MCTP_TRACE_KEY_INVALIDATED, "invalidated" },
- { MCTP_TRACE_KEY_CLOSED, "closed" })
+ { MCTP_TRACE_KEY_CLOSED, "closed" },
+ { MCTP_TRACE_KEY_DROPPED, "dropped" })
)
);
@@ -44,7 +44,25 @@ struct sockaddr_mctp_ext {
#define MCTP_TAG_MASK 0x07
#define MCTP_TAG_OWNER 0x08
+#define MCTP_TAG_PREALLOC 0x10
#define MCTP_OPT_ADDR_EXT 1
+#define SIOCMCTPALLOCTAG (SIOCPROTOPRIVATE + 0)
+#define SIOCMCTPDROPTAG (SIOCPROTOPRIVATE + 1)
+
+struct mctp_ioc_tag_ctl {
+ mctp_eid_t peer_addr;
+
+ /* For SIOCMCTPALLOCTAG: must be passed as zero, kernel will
+ * populate with the allocated tag value. Returned tag value will
+ * always have TO and PREALLOC set.
+ *
+ * For SIOCMCTPDROPTAG: userspace provides tag value to drop, from
+ * a prior SIOCMCTPALLOCTAG call (and so must have TO and PREALLOC set).
+ */
+ __u8 tag;
+ __u16 flags;
+};
+
#endif /* __UAPI_MCTP_H */
@@ -6,6 +6,7 @@
* Copyright (c) 2021 Google
*/
+#include <linux/compat.h>
#include <linux/if_arp.h>
#include <linux/net.h>
#include <linux/mctp.h>
@@ -21,6 +22,8 @@
/* socket implementation */
+static void mctp_sk_expire_keys(struct timer_list *timer);
+
static int mctp_release(struct socket *sock)
{
struct sock *sk = sock->sk;
@@ -99,13 +102,20 @@ static int mctp_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
struct sk_buff *skb;
if (addr) {
+ const u8 tagbits = MCTP_TAG_MASK | MCTP_TAG_OWNER |
+ MCTP_TAG_PREALLOC;
+
if (addrlen < sizeof(struct sockaddr_mctp))
return -EINVAL;
if (addr->smctp_family != AF_MCTP)
return -EINVAL;
if (!mctp_sockaddr_is_ok(addr))
return -EINVAL;
- if (addr->smctp_tag & ~(MCTP_TAG_MASK | MCTP_TAG_OWNER))
+ if (addr->smctp_tag & ~tagbits)
+ return -EINVAL;
+ /* can't preallocate a non-owned tag */
+ if (addr->smctp_tag & MCTP_TAG_PREALLOC &&
+ !(addr->smctp_tag & MCTP_TAG_OWNER))
return -EINVAL;
} else {
@@ -248,6 +258,32 @@ static int mctp_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
return rc;
}
+/* We're done with the key; invalidate, stop reassembly, and remove from lists.
+ */
+static void __mctp_key_remove(struct mctp_sk_key *key, struct net *net,
+ unsigned long flags, unsigned long reason)
+__releases(&key->lock)
+__must_hold(&net->mctp.keys_lock)
+{
+ struct sk_buff *skb;
+
+ trace_mctp_key_release(key, reason);
+ skb = key->reasm_head;
+ key->reasm_head = NULL;
+ key->reasm_dead = true;
+ key->valid = false;
+ mctp_dev_release_key(key->dev, key);
+ spin_unlock_irqrestore(&key->lock, flags);
+
+ hlist_del(&key->hlist);
+ hlist_del(&key->sklist);
+
+ /* unref for the lists */
+ mctp_key_unref(key);
+
+ kfree_skb(skb);
+}
+
static int mctp_setsockopt(struct socket *sock, int level, int optname,
sockptr_t optval, unsigned int optlen)
{
@@ -293,6 +329,115 @@ static int mctp_getsockopt(struct socket *sock, int level, int optname,
return -EINVAL;
}
+static int mctp_ioctl_alloctag(struct mctp_sock *msk, unsigned long arg)
+{
+ struct net *net = sock_net(&msk->sk);
+ struct mctp_sk_key *key = NULL;
+ struct mctp_ioc_tag_ctl ctl;
+ unsigned long flags;
+ u8 tag;
+
+ if (copy_from_user(&ctl, (void __user *)arg, sizeof(ctl)))
+ return -EFAULT;
+
+ if (ctl.tag)
+ return -EINVAL;
+
+ if (ctl.flags)
+ return -EINVAL;
+
+ key = mctp_alloc_local_tag(msk, ctl.peer_addr, MCTP_ADDR_ANY,
+ true, &tag);
+ if (IS_ERR(key))
+ return PTR_ERR(key);
+
+ ctl.tag = tag | MCTP_TAG_OWNER | MCTP_TAG_PREALLOC;
+ if (copy_to_user((void __user *)arg, &ctl, sizeof(ctl))) {
+ spin_lock_irqsave(&key->lock, flags);
+ __mctp_key_remove(key, net, flags, MCTP_TRACE_KEY_DROPPED);
+ mctp_key_unref(key);
+ return -EFAULT;
+ }
+
+ mctp_key_unref(key);
+ return 0;
+}
+
+static int mctp_ioctl_droptag(struct mctp_sock *msk, unsigned long arg)
+{
+ struct net *net = sock_net(&msk->sk);
+ struct mctp_ioc_tag_ctl ctl;
+ unsigned long flags, fl2;
+ struct mctp_sk_key *key;
+ struct hlist_node *tmp;
+ int rc;
+ u8 tag;
+
+ if (copy_from_user(&ctl, (void __user *)arg, sizeof(ctl)))
+ return -EFAULT;
+
+ if (ctl.flags)
+ return -EINVAL;
+
+ /* Must be a local tag, TO set, preallocated */
+ if ((ctl.tag & ~MCTP_TAG_MASK) != (MCTP_TAG_OWNER | MCTP_TAG_PREALLOC))
+ return -EINVAL;
+
+ tag = ctl.tag & MCTP_TAG_MASK;
+ rc = -EINVAL;
+
+ spin_lock_irqsave(&net->mctp.keys_lock, flags);
+ hlist_for_each_entry_safe(key, tmp, &msk->keys, sklist) {
+ /* we do an irqsave here, even though we know the irq state,
+ * so we have the flags to pass to __mctp_key_remove
+ */
+ spin_lock_irqsave(&key->lock, fl2);
+ if (key->manual_alloc &&
+ ctl.peer_addr == key->peer_addr &&
+ tag == key->tag) {
+ __mctp_key_remove(key, net, fl2,
+ MCTP_TRACE_KEY_DROPPED);
+ rc = 0;
+ } else {
+ spin_unlock_irqrestore(&key->lock, fl2);
+ }
+ }
+ spin_unlock_irqrestore(&net->mctp.keys_lock, flags);
+
+ return rc;
+}
+
+static int mctp_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
+{
+ struct mctp_sock *msk = container_of(sock->sk, struct mctp_sock, sk);
+
+ switch (cmd) {
+ case SIOCMCTPALLOCTAG:
+ return mctp_ioctl_alloctag(msk, arg);
+ case SIOCMCTPDROPTAG:
+ return mctp_ioctl_droptag(msk, arg);
+ }
+
+ return -EINVAL;
+}
+
+#ifdef CONFIG_COMPAT
+static int mctp_compat_ioctl(struct socket *sock, unsigned int cmd,
+ unsigned long arg)
+{
+ void __user *argp = compat_ptr(arg);
+
+ switch (cmd) {
+ /* These have compatible ptr layouts */
+ case SIOCMCTPALLOCTAG:
+ case SIOCMCTPDROPTAG:
+ return mctp_ioctl(sock, cmd, (unsigned long)argp);
+ }
+
+ return -ENOIOCTLCMD;
+}
+#endif
+
static const struct proto_ops mctp_dgram_ops = {
.family = PF_MCTP,
.release = mctp_release,
@@ -302,7 +447,7 @@ static const struct proto_ops mctp_dgram_ops = {
.accept = sock_no_accept,
.getname = sock_no_getname,
.poll = datagram_poll,
- .ioctl = sock_no_ioctl,
+ .ioctl = mctp_ioctl,
.gettstamp = sock_gettstamp,
.listen = sock_no_listen,
.shutdown = sock_no_shutdown,
@@ -312,6 +457,9 @@ static const struct proto_ops mctp_dgram_ops = {
.recvmsg = mctp_recvmsg,
.mmap = sock_no_mmap,
.sendpage = sock_no_sendpage,
+#ifdef CONFIG_COMPAT
+ .compat_ioctl = mctp_compat_ioctl,
+#endif
};
static void mctp_sk_expire_keys(struct timer_list *timer)
@@ -319,7 +467,7 @@ static void mctp_sk_expire_keys(struct timer_list *timer)
struct mctp_sock *msk = container_of(timer, struct mctp_sock,
key_expiry);
struct net *net = sock_net(&msk->sk);
- unsigned long next_expiry, flags;
+ unsigned long next_expiry, flags, fl2;
struct mctp_sk_key *key;
struct hlist_node *tmp;
bool next_expiry_valid = false;
@@ -327,15 +475,16 @@ static void mctp_sk_expire_keys(struct timer_list *timer)
spin_lock_irqsave(&net->mctp.keys_lock, flags);
hlist_for_each_entry_safe(key, tmp, &msk->keys, sklist) {
- spin_lock(&key->lock);
+ /* don't expire. manual_alloc is immutable, no locking
+ * required.
+ */
+ if (key->manual_alloc)
+ continue;
+ spin_lock_irqsave(&key->lock, fl2);
if (!time_after_eq(key->expiry, jiffies)) {
- trace_mctp_key_release(key, MCTP_TRACE_KEY_TIMEOUT);
- key->valid = false;
- hlist_del_rcu(&key->hlist);
- hlist_del_rcu(&key->sklist);
- spin_unlock(&key->lock);
- mctp_key_unref(key);
+ __mctp_key_remove(key, net, fl2,
+ MCTP_TRACE_KEY_TIMEOUT);
continue;
}
@@ -346,7 +495,7 @@ static void mctp_sk_expire_keys(struct timer_list *timer)
next_expiry = key->expiry;
next_expiry_valid = true;
}
- spin_unlock(&key->lock);
+ spin_unlock_irqrestore(&key->lock, fl2);
}
spin_unlock_irqrestore(&net->mctp.keys_lock, flags);
@@ -387,9 +536,9 @@ static void mctp_sk_unhash(struct sock *sk)
{
struct mctp_sock *msk = container_of(sk, struct mctp_sock, sk);
struct net *net = sock_net(sk);
+ unsigned long flags, fl2;
struct mctp_sk_key *key;
struct hlist_node *tmp;
- unsigned long flags;
/* remove from any type-based binds */
mutex_lock(&net->mctp.bind_lock);
@@ -399,20 +548,8 @@ static void mctp_sk_unhash(struct sock *sk)
/* remove tag allocations */
spin_lock_irqsave(&net->mctp.keys_lock, flags);
hlist_for_each_entry_safe(key, tmp, &msk->keys, sklist) {
- hlist_del(&key->sklist);
- hlist_del(&key->hlist);
-
- trace_mctp_key_release(key, MCTP_TRACE_KEY_CLOSED);
-
- spin_lock(&key->lock);
- kfree_skb(key->reasm_head);
- key->reasm_head = NULL;
- key->reasm_dead = true;
- key->valid = false;
- spin_unlock(&key->lock);
-
- /* key is no longer on the lookup lists, unref */
- mctp_key_unref(key);
+ spin_lock_irqsave(&key->lock, fl2);
+ __mctp_key_remove(key, net, fl2, MCTP_TRACE_KEY_CLOSED);
}
spin_unlock_irqrestore(&net->mctp.keys_lock, flags);
}
@@ -203,29 +203,38 @@ static int mctp_key_add(struct mctp_sk_key *key, struct mctp_sock *msk)
return rc;
}
-/* We're done with the key; unset valid and remove from lists. There may still
- * be outstanding refs on the key though...
+/* Helper for mctp_route_input().
+ * We're done with the key; unlock and unref the key.
+ * For the usual case of automatic expiry we remove the key from lists.
+ * In the case that manual allocation is set on a key we release the lock
+ * and local ref, reset reassembly, but don't remove from lists.
*/
-static void __mctp_key_unlock_drop(struct mctp_sk_key *key, struct net *net,
- unsigned long flags)
- __releases(&key->lock)
+static void __mctp_key_done_in(struct mctp_sk_key *key, struct net *net,
+ unsigned long flags, unsigned long reason)
+__releases(&key->lock)
{
struct sk_buff *skb;
+ trace_mctp_key_release(key, reason);
skb = key->reasm_head;
key->reasm_head = NULL;
- key->reasm_dead = true;
- key->valid = false;
- mctp_dev_release_key(key->dev, key);
+
+ if (!key->manual_alloc) {
+ key->reasm_dead = true;
+ key->valid = false;
+ mctp_dev_release_key(key->dev, key);
+ }
spin_unlock_irqrestore(&key->lock, flags);
- spin_lock_irqsave(&net->mctp.keys_lock, flags);
- hlist_del(&key->hlist);
- hlist_del(&key->sklist);
- spin_unlock_irqrestore(&net->mctp.keys_lock, flags);
+ if (!key->manual_alloc) {
+ spin_lock_irqsave(&net->mctp.keys_lock, flags);
+ hlist_del(&key->hlist);
+ hlist_del(&key->sklist);
+ spin_unlock_irqrestore(&net->mctp.keys_lock, flags);
- /* one unref for the lists */
- mctp_key_unref(key);
+ /* unref for the lists */
+ mctp_key_unref(key);
+ }
/* and one for the local reference */
mctp_key_unref(key);
@@ -379,9 +388,8 @@ static int mctp_route_input(struct mctp_route *route, struct sk_buff *skb)
/* we've hit a pending reassembly; not much we
* can do but drop it
*/
- trace_mctp_key_release(key,
- MCTP_TRACE_KEY_REPLIED);
- __mctp_key_unlock_drop(key, net, f);
+ __mctp_key_done_in(key, net, f,
+ MCTP_TRACE_KEY_REPLIED);
key = NULL;
}
rc = 0;
@@ -423,9 +431,8 @@ static int mctp_route_input(struct mctp_route *route, struct sk_buff *skb)
} else {
if (key->reasm_head || key->reasm_dead) {
/* duplicate start? drop everything */
- trace_mctp_key_release(key,
- MCTP_TRACE_KEY_INVALIDATED);
- __mctp_key_unlock_drop(key, net, f);
+ __mctp_key_done_in(key, net, f,
+ MCTP_TRACE_KEY_INVALIDATED);
rc = -EEXIST;
key = NULL;
} else {
@@ -448,10 +455,10 @@ static int mctp_route_input(struct mctp_route *route, struct sk_buff *skb)
* the reassembly/response key
*/
if (!rc && flags & MCTP_HDR_FLAG_EOM) {
+ msk = container_of(key->sk, struct mctp_sock, sk);
sock_queue_rcv_skb(key->sk, key->reasm_head);
key->reasm_head = NULL;
- trace_mctp_key_release(key, MCTP_TRACE_KEY_REPLIED);
- __mctp_key_unlock_drop(key, net, f);
+ __mctp_key_done_in(key, net, f, MCTP_TRACE_KEY_REPLIED);
key = NULL;
}
@@ -579,9 +586,9 @@ static void mctp_reserve_tag(struct net *net, struct mctp_sk_key *key,
/* Allocate a locally-owned tag value for (saddr, daddr), and reserve
* it for the socket msk
*/
-static struct mctp_sk_key *mctp_alloc_local_tag(struct mctp_sock *msk,
- mctp_eid_t saddr,
- mctp_eid_t daddr, u8 *tagp)
+struct mctp_sk_key *mctp_alloc_local_tag(struct mctp_sock *msk,
+ mctp_eid_t daddr, mctp_eid_t saddr,
+ bool manual, u8 *tagp)
{
struct net *net = sock_net(&msk->sk);
struct netns_mctp *mns = &net->mctp;
@@ -636,6 +643,7 @@ static struct mctp_sk_key *mctp_alloc_local_tag(struct mctp_sock *msk,
mctp_reserve_tag(net, key, msk);
trace_mctp_key_acquire(key);
+ key->manual_alloc = manual;
*tagp = key->tag;
}
@@ -649,6 +657,50 @@ static struct mctp_sk_key *mctp_alloc_local_tag(struct mctp_sock *msk,
return key;
}
+static struct mctp_sk_key *mctp_lookup_prealloc_tag(struct mctp_sock *msk,
+ mctp_eid_t daddr,
+ u8 req_tag, u8 *tagp)
+{
+ struct net *net = sock_net(&msk->sk);
+ struct netns_mctp *mns = &net->mctp;
+ struct mctp_sk_key *key, *tmp;
+ unsigned long flags;
+
+ req_tag &= ~(MCTP_TAG_PREALLOC | MCTP_TAG_OWNER);
+ key = NULL;
+
+ spin_lock_irqsave(&mns->keys_lock, flags);
+
+ hlist_for_each_entry(tmp, &mns->keys, hlist) {
+ if (tmp->tag != req_tag)
+ continue;
+
+ if (!mctp_address_matches(tmp->peer_addr, daddr))
+ continue;
+
+ if (!tmp->manual_alloc)
+ continue;
+
+ spin_lock(&tmp->lock);
+ if (tmp->valid) {
+ key = tmp;
+ refcount_inc(&key->refs);
+ spin_unlock(&tmp->lock);
+ break;
+ }
+ spin_unlock(&tmp->lock);
+ }
+ spin_unlock_irqrestore(&mns->keys_lock, flags);
+
+ if (!key)
+ return ERR_PTR(-ENOENT);
+
+ if (tagp)
+ *tagp = key->tag;
+
+ return key;
+}
+
/* routing lookups */
static bool mctp_rt_match_eid(struct mctp_route *rt,
unsigned int net, mctp_eid_t eid)
@@ -843,8 +895,14 @@ int mctp_local_output(struct sock *sk, struct mctp_route *rt,
if (rc)
goto out_release;
- if (req_tag & MCTP_HDR_FLAG_TO) {
- key = mctp_alloc_local_tag(msk, saddr, daddr, &tag);
+ if (req_tag & MCTP_TAG_OWNER) {
+ if (req_tag & MCTP_TAG_PREALLOC)
+ key = mctp_lookup_prealloc_tag(msk, daddr,
+ req_tag, &tag);
+ else
+ key = mctp_alloc_local_tag(msk, daddr, saddr,
+ false, &tag);
+
if (IS_ERR(key)) {
rc = PTR_ERR(key);
goto out_release;
@@ -855,7 +913,7 @@ int mctp_local_output(struct sock *sk, struct mctp_route *rt,
tag |= MCTP_HDR_FLAG_TO;
} else {
key = NULL;
- tag = req_tag;
+ tag = req_tag & MCTP_TAG_MASK;
}
skb->protocol = htons(ETH_P_MCTP);