From a5f7a5bb3b7f28ba7e4fa246775b29a0e5537255 Mon Sep 17 00:00:00 2001 From: Jinke Han Date: Tue, 8 Sep 2026 15:37:42 +0800 Subject: x86/kprobes: Fix crash when probing CS CALL instructions When using eBPF to probe CS CALL instructions within a function, a crash can be triggered. The eBPF tool probes offset 257 of the __hrtimer_run_queues() function: <__hrtimer_run_queues+249>: nopl 0x0(%rax,%rax,1) <__hrtimer_run_queues+254>: mov %r14,%rdi <__hrtimer_run_queues+257>: cs call <__x86_indirect_thunk_r12> <__hrtimer_run_queues+263>: mov %eax,%r12d <__hrtimer_run_queues+266>: xchg %ax,%ax <__hrtimer_run_queues+268>: mov %r13,%rdi Which triggers this crash: BUG: unable to handle page fault for address: 00000000000f41c9 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: 0002 [#1] SMP NOPTI CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P RIP: 0010:__hrtimer_run_queues+0x106/0x230 Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is at the 6th byte of the above CS CALL instruction. Since the CS CALL instruction occupies 6 bytes, the exception occurred in the middle of that call instruction. The root cause is that when using eBPF tools to probe in the middle of a function, a kprobe with INT3 is used as the underlying implementation. During single-step emulation of the original CALL instruction, int3_emulate_call() assumes that the probed CALL instruction is 5 bytes long. However, the actual CS-prefixed CALL instruction occupies 6 bytes, so it constructs an incorrect exception return address. When the CPU returns from the kprobe handler, the next instruction to be executed is at the address of the last byte of that CS CALL instruction. Coincidentally, starting from that address, the CPU fetches and decodes a completely different instruction, which ultimately triggers a kernel crash. Fix the issue by using the actual instruction length obtained from the instruction decoder when constructing the exception return address, rather than relying on the hardcoded CALL_INSN_SIZE macro. [ mingo: Refined the changelog ] Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step") Suggested-by: Masami Hiramatsu (Google) Signed-off-by: Jinke Han Signed-off-by: Ingo Molnar Reviewed-by: Masami Hiramatsu (Google) Acked-by: Yafang Shao Acked-by: Borislav Petkov Cc: Peter Zijlstra Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000 --- fs/lockd/host.c | 723 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 723 insertions(+) create mode 100644 fs/lockd/host.c (limited to 'fs/lockd/host.c') diff --git a/fs/lockd/host.c b/fs/lockd/host.c new file mode 100644 index 000000000..d572cb275 --- /dev/null +++ b/fs/lockd/host.c @@ -0,0 +1,723 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * linux/fs/lockd/host.c + * + * Management for NLM peer hosts. The nlm_host struct is shared + * between client and server implementation. The only reason to + * do so is to reduce code bloat. + * + * Copyright (C) 1996, Olaf Kirch + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +#include + +#include + +#include "lockd.h" +#include "netns.h" + +#define NLMDBG_FACILITY NLMDBG_HOSTCACHE +#define NLM_HOST_NRHASH 32 +#define NLM_HOST_REBIND (60 * HZ) +#define NLM_HOST_EXPIRE (300 * HZ) +#define NLM_HOST_COLLECT (120 * HZ) + +static struct hlist_head nlm_server_hosts[NLM_HOST_NRHASH]; +static struct hlist_head nlm_client_hosts[NLM_HOST_NRHASH]; + +#define for_each_host(host, chain, table) \ + for ((chain) = (table); \ + (chain) < (table) + NLM_HOST_NRHASH; ++(chain)) \ + hlist_for_each_entry((host), (chain), h_hash) + +#define for_each_host_safe(host, next, chain, table) \ + for ((chain) = (table); \ + (chain) < (table) + NLM_HOST_NRHASH; ++(chain)) \ + hlist_for_each_entry_safe((host), (next), \ + (chain), h_hash) + +static unsigned long nrhosts; +static DEFINE_MUTEX(nlm_host_mutex); + +static void nlm_gc_hosts(struct net *net); + +struct nlm_lookup_host_info { + const int server; /* search for server|client */ + const struct sockaddr *sap; /* address to search for */ + const size_t salen; /* it's length */ + const unsigned short protocol; /* transport to search for*/ + const u32 version; /* NLM version to search for */ + const char *hostname; /* remote's hostname */ + const size_t hostname_len; /* it's length */ + const int noresvport; /* use non-priv port */ + struct net *net; /* network namespace to bind */ + const struct cred *cred; +}; + +/* + * Hash function must work well on big- and little-endian platforms + */ +static unsigned int __nlm_hash32(const __be32 n) +{ + unsigned int hash = (__force u32)n ^ ((__force u32)n >> 16); + return hash ^ (hash >> 8); +} + +static unsigned int __nlm_hash_addr4(const struct sockaddr *sap) +{ + const struct sockaddr_in *sin = (struct sockaddr_in *)sap; + return __nlm_hash32(sin->sin_addr.s_addr); +} + +static unsigned int __nlm_hash_addr6(const struct sockaddr *sap) +{ + const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sap; + const struct in6_addr addr = sin6->sin6_addr; + return __nlm_hash32(addr.s6_addr32[0]) ^ + __nlm_hash32(addr.s6_addr32[1]) ^ + __nlm_hash32(addr.s6_addr32[2]) ^ + __nlm_hash32(addr.s6_addr32[3]); +} + +static unsigned int nlm_hash_address(const struct sockaddr *sap) +{ + unsigned int hash; + + switch (sap->sa_family) { + case AF_INET: + hash = __nlm_hash_addr4(sap); + break; + case AF_INET6: + hash = __nlm_hash_addr6(sap); + break; + default: + hash = 0; + } + return hash & (NLM_HOST_NRHASH - 1); +} + +/* + * Allocate and initialize an nlm_host. Common to both client and server. + */ +static struct nlm_host *nlm_alloc_host(struct nlm_lookup_host_info *ni, + struct nsm_handle *nsm) +{ + struct nlm_host *host = NULL; + unsigned long now = jiffies; + + if (nsm != NULL) + refcount_inc(&nsm->sm_count); + else { + nsm = nsm_get_handle(ni->net, ni->sap, ni->salen, + ni->hostname, ni->hostname_len); + if (unlikely(nsm == NULL)) { + dprintk("lockd: %s failed; no nsm handle\n", + __func__); + goto out; + } + } + + host = kmalloc_obj(*host); + if (unlikely(host == NULL)) { + dprintk("lockd: %s failed; no memory\n", __func__); + nsm_release(nsm); + goto out; + } + + memcpy(nlm_addr(host), ni->sap, ni->salen); + host->h_addrlen = ni->salen; + rpc_set_port(nlm_addr(host), 0); + host->h_srcaddrlen = 0; + + host->h_rpcclnt = NULL; + host->h_name = nsm->sm_name; + host->h_version = ni->version; + host->h_proto = ni->protocol; + host->h_reclaiming = 0; + host->h_server = ni->server; + host->h_noresvport = ni->noresvport; + host->h_inuse = 0; + init_waitqueue_head(&host->h_gracewait); + init_rwsem(&host->h_rwsem); + host->h_state = 0; + host->h_nsmstate = 0; + host->h_pidcount = 0; + refcount_set(&host->h_count, 1); + mutex_init(&host->h_mutex); + host->h_nextrebind = now + NLM_HOST_REBIND; + host->h_expires = now + NLM_HOST_EXPIRE; + INIT_LIST_HEAD(&host->h_lockowners); + spin_lock_init(&host->h_lock); + INIT_LIST_HEAD(&host->h_granted); + INIT_LIST_HEAD(&host->h_reclaim); + host->h_nsmhandle = nsm; + host->h_addrbuf = nsm->sm_addrbuf; + host->net = ni->net; + host->h_cred = get_cred(ni->cred); + strscpy(host->nodename, utsname()->nodename, sizeof(host->nodename)); + +out: + return host; +} + +/* + * Destroy an nlm_host and free associated resources + * + * Caller must hold nlm_host_mutex. + */ +static void nlm_destroy_host_locked(struct nlm_host *host) +{ + struct rpc_clnt *clnt; + struct lockd_net *ln = net_generic(host->net, lockd_net_id); + + dprintk("lockd: destroy host %s\n", host->h_name); + + hlist_del_init(&host->h_hash); + + nsm_unmonitor(host); + nsm_release(host->h_nsmhandle); + + clnt = host->h_rpcclnt; + if (clnt != NULL) + rpc_shutdown_client(clnt); + put_cred(host->h_cred); + kfree(host); + + ln->nrhosts--; + nrhosts--; +} + +/** + * nlmclnt_lookup_host - Find an NLM host handle matching a remote server + * @sap: network address of server + * @salen: length of server address + * @protocol: transport protocol to use + * @version: NLM protocol version + * @hostname: '\0'-terminated hostname of server + * @noresvport: 1 if non-privileged port should be used + * @net: pointer to net namespace + * @cred: pointer to cred + * + * Returns an nlm_host structure that matches the passed-in + * [server address, transport protocol, NLM version, server hostname]. + * If one doesn't already exist in the host cache, a new handle is + * created and returned. + */ +struct nlm_host *nlmclnt_lookup_host(const struct sockaddr *sap, + const size_t salen, + const unsigned short protocol, + const u32 version, + const char *hostname, + int noresvport, + struct net *net, + const struct cred *cred) +{ + struct nlm_lookup_host_info ni = { + .server = 0, + .sap = sap, + .salen = salen, + .protocol = protocol, + .version = version, + .hostname = hostname, + .hostname_len = strlen(hostname), + .noresvport = noresvport, + .net = net, + .cred = cred, + }; + struct hlist_head *chain; + struct nlm_host *host; + struct nsm_handle *nsm = NULL; + struct lockd_net *ln = net_generic(net, lockd_net_id); + + dprintk("lockd: %s(host='%s', vers=%u, proto=%s)\n", __func__, + (hostname ? hostname : ""), version, + (protocol == IPPROTO_UDP ? "udp" : "tcp")); + + mutex_lock(&nlm_host_mutex); + + chain = &nlm_client_hosts[nlm_hash_address(sap)]; + hlist_for_each_entry(host, chain, h_hash) { + if (host->net != net) + continue; + if (!rpc_cmp_addr(nlm_addr(host), sap)) + continue; + + /* Same address. Share an NSM handle if we already have one */ + if (nsm == NULL) + nsm = host->h_nsmhandle; + + if (host->h_proto != protocol) + continue; + if (host->h_version != version) + continue; + + nlm_get_host(host); + dprintk("lockd: %s found host %s (%s)\n", __func__, + host->h_name, host->h_addrbuf); + goto out; + } + + host = nlm_alloc_host(&ni, nsm); + if (unlikely(host == NULL)) + goto out; + + hlist_add_head(&host->h_hash, chain); + ln->nrhosts++; + nrhosts++; + + dprintk("lockd: %s created host %s (%s)\n", __func__, + host->h_name, host->h_addrbuf); + +out: + mutex_unlock(&nlm_host_mutex); + return host; +} + +/** + * nlmclnt_release_host - release client nlm_host + * @host: nlm_host to release + * + */ +void nlmclnt_release_host(struct nlm_host *host) +{ + if (host == NULL) + return; + + dprintk("lockd: release client host %s\n", host->h_name); + + WARN_ON_ONCE(host->h_server); + + if (refcount_dec_and_mutex_lock(&host->h_count, &nlm_host_mutex)) { + WARN_ON_ONCE(!list_empty(&host->h_lockowners)); + WARN_ON_ONCE(!list_empty(&host->h_granted)); + WARN_ON_ONCE(!list_empty(&host->h_reclaim)); + + nlm_destroy_host_locked(host); + mutex_unlock(&nlm_host_mutex); + } +} + +/* Callback for rpc_cancel_tasks() - matches all tasks for cancellation */ +static bool nlmclnt_match_all(const struct rpc_task *task, const void *data) +{ + return true; +} + +/** + * nlmclnt_shutdown_rpc_clnt - safely shut down NLM client RPC operations + * @host: nlm_host to shut down + * + * Cancels outstanding RPC tasks and marks the client as shut down. + * Synchronizes with nlmclnt_release_host() via nlm_host_mutex to prevent + * races between shutdown and host destruction. Safe to call if h_rpcclnt + * is NULL or already shut down. + */ +void nlmclnt_shutdown_rpc_clnt(struct nlm_host *host) +{ + struct rpc_clnt *clnt; + + mutex_lock(&nlm_host_mutex); + clnt = host->h_rpcclnt; + if (clnt) { + clnt->cl_shutdown = 1; + rpc_cancel_tasks(clnt, -EIO, nlmclnt_match_all, NULL); + } + mutex_unlock(&nlm_host_mutex); +} +EXPORT_SYMBOL_GPL(nlmclnt_shutdown_rpc_clnt); + +/** + * nlmsvc_lookup_host - Find an NLM host handle matching a remote client + * @rqstp: incoming NLM request + * @hostname: name of client host + * @hostname_len: length of client hostname + * + * Returns an nlm_host structure that matches the [client address, + * transport protocol, NLM version, client hostname] of the passed-in + * NLM request. If one doesn't already exist in the host cache, a + * new handle is created and returned. + * + * Before possibly creating a new nlm_host, construct a sockaddr + * for a specific source address in case the local system has + * multiple network addresses. The family of the address in + * rq_daddr is guaranteed to be the same as the family of the + * address in rq_addr, so it's safe to use the same family for + * the source address. + */ +struct nlm_host *nlmsvc_lookup_host(const struct svc_rqst *rqstp, + const char *hostname, + const size_t hostname_len) +{ + struct hlist_head *chain; + struct nlm_host *host = NULL; + struct nsm_handle *nsm = NULL; + struct sockaddr *src_sap = svc_daddr(rqstp); + size_t src_len = rqstp->rq_daddrlen; + struct net *net = SVC_NET(rqstp); + struct nlm_lookup_host_info ni = { + .server = 1, + .sap = svc_addr(rqstp), + .salen = rqstp->rq_addrlen, + .protocol = rqstp->rq_prot, + .version = rqstp->rq_vers, + .hostname = hostname, + .hostname_len = hostname_len, + .net = net, + }; + struct lockd_net *ln = net_generic(net, lockd_net_id); + + dprintk("lockd: %s(host='%.*s', vers=%u, proto=%s)\n", __func__, + (int)hostname_len, hostname, rqstp->rq_vers, + (rqstp->rq_prot == IPPROTO_UDP ? "udp" : "tcp")); + + mutex_lock(&nlm_host_mutex); + + if (time_after_eq(jiffies, ln->next_gc)) + nlm_gc_hosts(net); + + chain = &nlm_server_hosts[nlm_hash_address(ni.sap)]; + hlist_for_each_entry(host, chain, h_hash) { + if (host->net != net) + continue; + if (!rpc_cmp_addr(nlm_addr(host), ni.sap)) + continue; + + /* Same address. Share an NSM handle if we already have one */ + if (nsm == NULL) + nsm = host->h_nsmhandle; + + if (host->h_proto != ni.protocol) + continue; + if (host->h_version != ni.version) + continue; + if (!rpc_cmp_addr(nlm_srcaddr(host), src_sap)) + continue; + + /* Move to head of hash chain. */ + hlist_del(&host->h_hash); + hlist_add_head(&host->h_hash, chain); + + nlm_get_host(host); + dprintk("lockd: %s found host %s (%s)\n", + __func__, host->h_name, host->h_addrbuf); + goto out; + } + + host = nlm_alloc_host(&ni, nsm); + if (unlikely(host == NULL)) + goto out; + + memcpy(nlm_srcaddr(host), src_sap, src_len); + host->h_srcaddrlen = src_len; + hlist_add_head(&host->h_hash, chain); + ln->nrhosts++; + nrhosts++; + + refcount_inc(&host->h_count); + + dprintk("lockd: %s created host %s (%s)\n", + __func__, host->h_name, host->h_addrbuf); + +out: + mutex_unlock(&nlm_host_mutex); + return host; +} + +/** + * nlmsvc_release_host - release server nlm_host + * @host: nlm_host to release + * + * Host is destroyed later in nlm_gc_host(). + */ +void nlmsvc_release_host(struct nlm_host *host) +{ + if (host == NULL) + return; + + dprintk("lockd: release server host %s\n", host->h_name); + + WARN_ON_ONCE(!host->h_server); + refcount_dec(&host->h_count); +} + +/* + * Create the NLM RPC client for an NLM peer + */ +struct rpc_clnt * +nlm_bind_host(struct nlm_host *host) +{ + struct rpc_clnt *clnt; + + dprintk("lockd: nlm_bind_host %s (%s)\n", + host->h_name, host->h_addrbuf); + + /* Lock host handle */ + mutex_lock(&host->h_mutex); + + /* If we've already created an RPC client, check whether + * RPC rebind is required + */ + if ((clnt = host->h_rpcclnt) != NULL) { + nlm_rebind_host(host); + } else { + unsigned long increment = nlm_timeout * HZ; + struct rpc_timeout timeparms = { + .to_initval = increment, + .to_increment = increment, + .to_maxval = increment * 6UL, + .to_retries = 5U, + }; + struct rpc_create_args args = { + .net = host->net, + .protocol = host->h_proto, + .address = nlm_addr(host), + .addrsize = host->h_addrlen, + .timeout = &timeparms, + .servername = host->h_name, + .program = &nlm_program, + .version = host->h_version, + .authflavor = RPC_AUTH_UNIX, + .flags = (RPC_CLNT_CREATE_NOPING | + RPC_CLNT_CREATE_AUTOBIND | + RPC_CLNT_CREATE_REUSEPORT), + .cred = host->h_cred, + }; + + /* + * lockd retries server side blocks automatically so we want + * those to be soft RPC calls. Client side calls need to be + * hard RPC tasks. + */ + if (!host->h_server) + args.flags |= RPC_CLNT_CREATE_HARDRTRY; + if (host->h_noresvport) + args.flags |= RPC_CLNT_CREATE_NONPRIVPORT; + if (host->h_srcaddrlen) + args.saddress = nlm_srcaddr(host); + + clnt = rpc_create(&args); + if (!IS_ERR(clnt)) + host->h_rpcclnt = clnt; + else { + printk("lockd: couldn't create RPC handle for %s\n", host->h_name); + clnt = NULL; + } + } + + mutex_unlock(&host->h_mutex); + return clnt; +} + +/** + * nlm_rebind_host - If needed, force a portmap lookup of the peer's lockd port + * @host: NLM host handle for peer + * + * This is not needed when using a connection-oriented protocol, such as TCP. + * The existing autobind mechanism is sufficient to force a rebind when + * required, e.g. on connection state transitions. + */ +void +nlm_rebind_host(struct nlm_host *host) +{ + if (host->h_proto != IPPROTO_UDP) + return; + + if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) { + rpc_force_rebind(host->h_rpcclnt); + host->h_nextrebind = jiffies + NLM_HOST_REBIND; + } +} + +/* + * Increment NLM host count + */ +struct nlm_host * nlm_get_host(struct nlm_host *host) +{ + if (host) { + dprintk("lockd: get host %s\n", host->h_name); + refcount_inc(&host->h_count); + host->h_expires = jiffies + NLM_HOST_EXPIRE; + } + return host; +} + +static struct nlm_host *next_host_state(struct hlist_head *cache, + struct nsm_handle *nsm, + const struct lockd_reboot *info) +{ + struct nlm_host *host; + struct hlist_head *chain; + + mutex_lock(&nlm_host_mutex); + for_each_host(host, chain, cache) { + if (host->h_nsmhandle == nsm + && host->h_nsmstate != info->state) { + host->h_nsmstate = info->state; + host->h_state++; + + nlm_get_host(host); + mutex_unlock(&nlm_host_mutex); + return host; + } + } + + mutex_unlock(&nlm_host_mutex); + return NULL; +} + +/** + * nlm_host_rebooted - Release all resources held by rebooted host + * @net: network namespace + * @info: pointer to decoded results of NLM_SM_NOTIFY call + * + * We were notified that the specified host has rebooted. Release + * all resources held by that peer. + */ +void nlm_host_rebooted(const struct net *net, const struct lockd_reboot *info) +{ + struct nsm_handle *nsm; + struct nlm_host *host; + + nsm = nsm_reboot_lookup(net, info); + if (unlikely(nsm == NULL)) + return; + + /* Mark all hosts tied to this NSM state as having rebooted. + * We run the loop repeatedly, because we drop the host table + * lock for this. + * To avoid processing a host several times, we match the nsmstate. + */ + while ((host = next_host_state(nlm_server_hosts, nsm, info)) != NULL) { + nlmsvc_free_host_resources(host); + nlmsvc_release_host(host); + } + while ((host = next_host_state(nlm_client_hosts, nsm, info)) != NULL) { + nlmclnt_recovery(host); + nlmclnt_release_host(host); + } + + nsm_release(nsm); +} + +static void nlm_complain_hosts(struct net *net) +{ + struct hlist_head *chain; + struct nlm_host *host; + + if (net) { + struct lockd_net *ln = net_generic(net, lockd_net_id); + + if (ln->nrhosts == 0) + return; + pr_warn("lockd: couldn't shutdown host module for net %x!\n", + net->ns.inum); + dprintk("lockd: %lu hosts left in net %x:\n", ln->nrhosts, + net->ns.inum); + } else { + if (nrhosts == 0) + return; + printk(KERN_WARNING "lockd: couldn't shutdown host module!\n"); + dprintk("lockd: %lu hosts left:\n", nrhosts); + } + + for_each_host(host, chain, nlm_server_hosts) { + if (net && host->net != net) + continue; + dprintk(" %s (cnt %d use %d exp %ld net %x)\n", + host->h_name, refcount_read(&host->h_count), + host->h_inuse, host->h_expires, host->net->ns.inum); + } +} + +void +nlm_shutdown_hosts_net(struct net *net) +{ + struct hlist_head *chain; + struct nlm_host *host; + + mutex_lock(&nlm_host_mutex); + + /* First, make all hosts eligible for gc */ + dprintk("lockd: nuking all hosts in net %x...\n", + net ? net->ns.inum : 0); + for_each_host(host, chain, nlm_server_hosts) { + if (net && host->net != net) + continue; + host->h_expires = jiffies - 1; + if (host->h_rpcclnt) { + rpc_shutdown_client(host->h_rpcclnt); + host->h_rpcclnt = NULL; + } + nlmsvc_free_host_resources(host); + } + + /* Then, perform a garbage collection pass */ + nlm_gc_hosts(net); + nlm_complain_hosts(net); + mutex_unlock(&nlm_host_mutex); +} + +/* + * Shut down the hosts module. + * Note that this routine is called only at server shutdown time. + */ +void +nlm_shutdown_hosts(void) +{ + dprintk("lockd: shutting down host module\n"); + nlm_shutdown_hosts_net(NULL); +} + +/* + * Garbage collect any unused NLM hosts. + * This GC combines reference counting for async operations with + * mark & sweep for resources held by remote clients. + */ +static void +nlm_gc_hosts(struct net *net) +{ + struct hlist_head *chain; + struct hlist_node *next; + struct nlm_host *host; + + dprintk("lockd: host garbage collection for net %x\n", + net ? net->ns.inum : 0); + for_each_host(host, chain, nlm_server_hosts) { + if (net && host->net != net) + continue; + host->h_inuse = 0; + } + + /* Mark all hosts that hold locks, blocks or shares */ + nlmsvc_mark_resources(net); + + for_each_host_safe(host, next, chain, nlm_server_hosts) { + if (net && host->net != net) + continue; + if (host->h_inuse || time_before(jiffies, host->h_expires)) { + dprintk("nlm_gc_hosts skipping %s " + "(cnt %d use %d exp %ld net %x)\n", + host->h_name, refcount_read(&host->h_count), + host->h_inuse, host->h_expires, + host->net->ns.inum); + continue; + } + if (refcount_dec_if_one(&host->h_count)) + nlm_destroy_host_locked(host); + } + + if (net) { + struct lockd_net *ln = net_generic(net, lockd_net_id); + + ln->next_gc = jiffies + NLM_HOST_COLLECT; + } +} -- cgit v1.3.1