From 63ed1aab3d40aa61aaa66819bdce9377ac7f40fa Mon Sep 17 00:00:00 2001 From: Matt Johnston Date: Wed, 9 Feb 2022 12:05:57 +0800 Subject: [PATCH] mctp: Add SIOCMCTP{ALLOC,DROP}TAG ioctls for tag control This change adds a couple of new ioctls for mctp sockets: SIOCMCTPALLOCTAG and SIOCMCTPDROPTAG. These ioctls provide facilities for explicit allocation / release of tags, overriding the automatic allocate-on-send/release-on-reply and timeout behaviours. This allows userspace more control over messages that may not fit a simple request/response model. In order to indicate a pre-allocated tag to the sendmsg() syscall, we introduce a new flag to the struct sockaddr_mctp.smctp_tag value: MCTP_TAG_PREALLOC. Additional changes from Jeremy Kerr . Contains a fix that was: Reported-by: kernel test robot Signed-off-by: Matt Johnston Signed-off-by: Jeremy Kerr Signed-off-by: David S. Miller --- Documentation/networking/mctp.rst | 48 ++++++++ include/net/mctp.h | 11 +- include/trace/events/mctp.h | 5 +- include/uapi/linux/mctp.h | 18 +++ net/mctp/af_mctp.c | 189 ++++++++++++++++++++++++++---- net/mctp/route.c | 114 +++++++++++++----- 6 files changed, 329 insertions(+), 56 deletions(-) diff --git a/Documentation/networking/mctp.rst b/Documentation/networking/mctp.rst index 46f74bffce0f..c628cb5406d2 100644 --- a/Documentation/networking/mctp.rst +++ b/Documentation/networking/mctp.rst @@ -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 ================ diff --git a/include/net/mctp.h b/include/net/mctp.h index 706d329dd8e8..e80a4baf8379 100644 --- a/include/net/mctp.h +++ b/include/net/mctp.h @@ -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); diff --git a/include/trace/events/mctp.h b/include/trace/events/mctp.h index 175b057c507f..165cf25f77a7 100644 --- a/include/trace/events/mctp.h +++ b/include/trace/events/mctp.h @@ -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" }) ) ); diff --git a/include/uapi/linux/mctp.h b/include/uapi/linux/mctp.h index 07b0318716fc..154ab56651f1 100644 --- a/include/uapi/linux/mctp.h +++ b/include/uapi/linux/mctp.h @@ -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 */ diff --git a/net/mctp/af_mctp.c b/net/mctp/af_mctp.c index c921de63b494..f0702d920d8d 100644 --- a/net/mctp/af_mctp.c +++ b/net/mctp/af_mctp.c @@ -6,6 +6,7 @@ * Copyright (c) 2021 Google */ +#include #include #include #include @@ -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); } diff --git a/net/mctp/route.c b/net/mctp/route.c index 35f72e99e188..17e3482aa770 100644 --- a/net/mctp/route.c +++ b/net/mctp/route.c @@ -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);