diff options
Diffstat (limited to 'net/sunrpc/svc.c')
| -rw-r--r-- | net/sunrpc/svc.c | 1698 |
1 files changed, 1698 insertions, 0 deletions
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c new file mode 100644 index 000000000..9b0b21ccc --- /dev/null +++ b/net/sunrpc/svc.c @@ -0,0 +1,1698 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * linux/net/sunrpc/svc.c + * + * High-level RPC service routines + * + * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de> + * + * Multiple threads pools and NUMAisation + * Copyright (c) 2006 Silicon Graphics, Inc. + * by Greg Banks <gnb@melbourne.sgi.com> + */ + +#include <linux/linkage.h> +#include <linux/sched/signal.h> +#include <linux/errno.h> +#include <linux/net.h> +#include <linux/in.h> +#include <linux/mm.h> +#include <linux/interrupt.h> +#include <linux/module.h> +#include <linux/kthread.h> +#include <linux/slab.h> + +#include <linux/sunrpc/types.h> +#include <linux/sunrpc/xdr.h> +#include <linux/sunrpc/stats.h> +#include <linux/sunrpc/svcsock.h> +#include <linux/sunrpc/clnt.h> +#include <linux/sunrpc/bc_xprt.h> + +#include <trace/events/sunrpc.h> + +#include "fail.h" + +#define RPCDBG_FACILITY RPCDBG_SVCDSP + +static void svc_unregister(const struct svc_serv *serv, struct net *net); + +#define SVC_POOL_DEFAULT SVC_POOL_GLOBAL + +/* + * Mode for mapping cpus to pools. + */ +enum { + SVC_POOL_AUTO = -1, /* choose one of the others */ + SVC_POOL_GLOBAL, /* no mapping, just a single global pool + * (legacy & UP mode) */ + SVC_POOL_PERCPU, /* one pool per cpu */ + SVC_POOL_PERNODE /* one pool per numa node */ +}; + +/* + * Structure for mapping cpus to pools and vice versa. + * Setup once during sunrpc initialisation. + */ + +struct svc_pool_map { + int count; /* How many svc_servs use us */ + int mode; /* Note: int not enum to avoid + * warnings about "enumeration value + * not handled in switch" */ + unsigned int npools; + unsigned int *pool_to; /* maps pool id to cpu or node */ + unsigned int *to_pool; /* maps cpu or node to pool id */ +}; + +static struct svc_pool_map svc_pool_map = { + .mode = SVC_POOL_DEFAULT +}; + +static DEFINE_MUTEX(svc_pool_map_mutex);/* protects svc_pool_map.count only */ + +static int +param_set_pool_mode(const char *val, const struct kernel_param *kp) +{ + int *ip = (int *)kp->arg; + struct svc_pool_map *m = &svc_pool_map; + int err; + + mutex_lock(&svc_pool_map_mutex); + + err = -EBUSY; + if (m->count) + goto out; + + err = 0; + if (!strncmp(val, "auto", 4)) + *ip = SVC_POOL_AUTO; + else if (!strncmp(val, "global", 6)) + *ip = SVC_POOL_GLOBAL; + else if (!strncmp(val, "percpu", 6)) + *ip = SVC_POOL_PERCPU; + else if (!strncmp(val, "pernode", 7)) + *ip = SVC_POOL_PERNODE; + else + err = -EINVAL; + +out: + mutex_unlock(&svc_pool_map_mutex); + return err; +} + +static int +param_get_pool_mode(char *buf, const struct kernel_param *kp) +{ + int *ip = (int *)kp->arg; + + switch (*ip) + { + case SVC_POOL_AUTO: + return strlcpy(buf, "auto\n", 20); + case SVC_POOL_GLOBAL: + return strlcpy(buf, "global\n", 20); + case SVC_POOL_PERCPU: + return strlcpy(buf, "percpu\n", 20); + case SVC_POOL_PERNODE: + return strlcpy(buf, "pernode\n", 20); + default: + return sprintf(buf, "%d\n", *ip); + } +} + +module_param_call(pool_mode, param_set_pool_mode, param_get_pool_mode, + &svc_pool_map.mode, 0644); + +/* + * Detect best pool mapping mode heuristically, + * according to the machine's topology. + */ +static int +svc_pool_map_choose_mode(void) +{ + unsigned int node; + + if (nr_online_nodes > 1) { + /* + * Actually have multiple NUMA nodes, + * so split pools on NUMA node boundaries + */ + return SVC_POOL_PERNODE; + } + + node = first_online_node; + if (nr_cpus_node(node) > 2) { + /* + * Non-trivial SMP, or CONFIG_NUMA on + * non-NUMA hardware, e.g. with a generic + * x86_64 kernel on Xeons. In this case we + * want to divide the pools on cpu boundaries. + */ + return SVC_POOL_PERCPU; + } + + /* default: one global pool */ + return SVC_POOL_GLOBAL; +} + +/* + * Allocate the to_pool[] and pool_to[] arrays. + * Returns 0 on success or an errno. + */ +static int +svc_pool_map_alloc_arrays(struct svc_pool_map *m, unsigned int maxpools) +{ + m->to_pool = kcalloc(maxpools, sizeof(unsigned int), GFP_KERNEL); + if (!m->to_pool) + goto fail; + m->pool_to = kcalloc(maxpools, sizeof(unsigned int), GFP_KERNEL); + if (!m->pool_to) + goto fail_free; + + return 0; + +fail_free: + kfree(m->to_pool); + m->to_pool = NULL; +fail: + return -ENOMEM; +} + +/* + * Initialise the pool map for SVC_POOL_PERCPU mode. + * Returns number of pools or <0 on error. + */ +static int +svc_pool_map_init_percpu(struct svc_pool_map *m) +{ + unsigned int maxpools = nr_cpu_ids; + unsigned int pidx = 0; + unsigned int cpu; + int err; + + err = svc_pool_map_alloc_arrays(m, maxpools); + if (err) + return err; + + for_each_online_cpu(cpu) { + BUG_ON(pidx >= maxpools); + m->to_pool[cpu] = pidx; + m->pool_to[pidx] = cpu; + pidx++; + } + /* cpus brought online later all get mapped to pool0, sorry */ + + return pidx; +}; + + +/* + * Initialise the pool map for SVC_POOL_PERNODE mode. + * Returns number of pools or <0 on error. + */ +static int +svc_pool_map_init_pernode(struct svc_pool_map *m) +{ + unsigned int maxpools = nr_node_ids; + unsigned int pidx = 0; + unsigned int node; + int err; + + err = svc_pool_map_alloc_arrays(m, maxpools); + if (err) + return err; + + for_each_node_with_cpus(node) { + /* some architectures (e.g. SN2) have cpuless nodes */ + BUG_ON(pidx > maxpools); + m->to_pool[node] = pidx; + m->pool_to[pidx] = node; + pidx++; + } + /* nodes brought online later all get mapped to pool0, sorry */ + + return pidx; +} + + +/* + * Add a reference to the global map of cpus to pools (and + * vice versa) if pools are in use. + * Initialise the map if we're the first user. + * Returns the number of pools. If this is '1', no reference + * was taken. + */ +static unsigned int +svc_pool_map_get(void) +{ + struct svc_pool_map *m = &svc_pool_map; + int npools = -1; + + mutex_lock(&svc_pool_map_mutex); + + if (m->count++) { + mutex_unlock(&svc_pool_map_mutex); + WARN_ON_ONCE(m->npools <= 1); + return m->npools; + } + + if (m->mode == SVC_POOL_AUTO) + m->mode = svc_pool_map_choose_mode(); + + switch (m->mode) { + case SVC_POOL_PERCPU: + npools = svc_pool_map_init_percpu(m); + break; + case SVC_POOL_PERNODE: + npools = svc_pool_map_init_pernode(m); + break; + } + + if (npools <= 0) { + /* default, or memory allocation failure */ + npools = 1; + m->mode = SVC_POOL_GLOBAL; + } + m->npools = npools; + + if (npools == 1) + /* service is unpooled, so doesn't hold a reference */ + m->count--; + + mutex_unlock(&svc_pool_map_mutex); + return npools; +} + +/* + * Drop a reference to the global map of cpus to pools, if + * pools were in use, i.e. if npools > 1. + * When the last reference is dropped, the map data is + * freed; this allows the sysadmin to change the pool + * mode using the pool_mode module option without + * rebooting or re-loading sunrpc.ko. + */ +static void +svc_pool_map_put(int npools) +{ + struct svc_pool_map *m = &svc_pool_map; + + if (npools <= 1) + return; + mutex_lock(&svc_pool_map_mutex); + + if (!--m->count) { + kfree(m->to_pool); + m->to_pool = NULL; + kfree(m->pool_to); + m->pool_to = NULL; + m->npools = 0; + } + + mutex_unlock(&svc_pool_map_mutex); +} + +static int svc_pool_map_get_node(unsigned int pidx) +{ + const struct svc_pool_map *m = &svc_pool_map; + + if (m->count) { + if (m->mode == SVC_POOL_PERCPU) + return cpu_to_node(m->pool_to[pidx]); + if (m->mode == SVC_POOL_PERNODE) + return m->pool_to[pidx]; + } + return NUMA_NO_NODE; +} +/* + * Set the given thread's cpus_allowed mask so that it + * will only run on cpus in the given pool. + */ +static inline void +svc_pool_map_set_cpumask(struct task_struct *task, unsigned int pidx) +{ + struct svc_pool_map *m = &svc_pool_map; + unsigned int node = m->pool_to[pidx]; + + /* + * The caller checks for sv_nrpools > 1, which + * implies that we've been initialized. + */ + WARN_ON_ONCE(m->count == 0); + if (m->count == 0) + return; + + switch (m->mode) { + case SVC_POOL_PERCPU: + { + set_cpus_allowed_ptr(task, cpumask_of(node)); + break; + } + case SVC_POOL_PERNODE: + { + set_cpus_allowed_ptr(task, cpumask_of_node(node)); + break; + } + } +} + +/** + * svc_pool_for_cpu - Select pool to run a thread on this cpu + * @serv: An RPC service + * + * Use the active CPU and the svc_pool_map's mode setting to + * select the svc thread pool to use. Once initialized, the + * svc_pool_map does not change. + * + * Return value: + * A pointer to an svc_pool + */ +struct svc_pool *svc_pool_for_cpu(struct svc_serv *serv) +{ + struct svc_pool_map *m = &svc_pool_map; + int cpu = raw_smp_processor_id(); + unsigned int pidx = 0; + + if (serv->sv_nrpools <= 1) + return serv->sv_pools; + + switch (m->mode) { + case SVC_POOL_PERCPU: + pidx = m->to_pool[cpu]; + break; + case SVC_POOL_PERNODE: + pidx = m->to_pool[cpu_to_node(cpu)]; + break; + } + + return &serv->sv_pools[pidx % serv->sv_nrpools]; +} + +int svc_rpcb_setup(struct svc_serv *serv, struct net *net) +{ + int err; + + err = rpcb_create_local(net); + if (err) + return err; + + /* Remove any stale portmap registrations */ + svc_unregister(serv, net); + return 0; +} +EXPORT_SYMBOL_GPL(svc_rpcb_setup); + +void svc_rpcb_cleanup(struct svc_serv *serv, struct net *net) +{ + svc_unregister(serv, net); + rpcb_put_local(net); +} +EXPORT_SYMBOL_GPL(svc_rpcb_cleanup); + +static int svc_uses_rpcbind(struct svc_serv *serv) +{ + struct svc_program *progp; + unsigned int i; + + for (progp = serv->sv_program; progp; progp = progp->pg_next) { + for (i = 0; i < progp->pg_nvers; i++) { + if (progp->pg_vers[i] == NULL) + continue; + if (!progp->pg_vers[i]->vs_hidden) + return 1; + } + } + + return 0; +} + +int svc_bind(struct svc_serv *serv, struct net *net) +{ + if (!svc_uses_rpcbind(serv)) + return 0; + return svc_rpcb_setup(serv, net); +} +EXPORT_SYMBOL_GPL(svc_bind); + +#if defined(CONFIG_SUNRPC_BACKCHANNEL) +static void +__svc_init_bc(struct svc_serv *serv) +{ + INIT_LIST_HEAD(&serv->sv_cb_list); + spin_lock_init(&serv->sv_cb_lock); + init_waitqueue_head(&serv->sv_cb_waitq); +} +#else +static void +__svc_init_bc(struct svc_serv *serv) +{ +} +#endif + +/* + * Create an RPC service + */ +static struct svc_serv * +__svc_create(struct svc_program *prog, unsigned int bufsize, int npools, + int (*threadfn)(void *data)) +{ + struct svc_serv *serv; + unsigned int vers; + unsigned int xdrsize; + unsigned int i; + + if (!(serv = kzalloc(sizeof(*serv), GFP_KERNEL))) + return NULL; + serv->sv_name = prog->pg_name; + serv->sv_program = prog; + kref_init(&serv->sv_refcnt); + serv->sv_stats = prog->pg_stats; + if (bufsize > RPCSVC_MAXPAYLOAD) + bufsize = RPCSVC_MAXPAYLOAD; + serv->sv_max_payload = bufsize? bufsize : 4096; + serv->sv_max_mesg = roundup(serv->sv_max_payload + PAGE_SIZE, PAGE_SIZE); + serv->sv_threadfn = threadfn; + xdrsize = 0; + while (prog) { + prog->pg_lovers = prog->pg_nvers-1; + for (vers=0; vers<prog->pg_nvers ; vers++) + if (prog->pg_vers[vers]) { + prog->pg_hivers = vers; + if (prog->pg_lovers > vers) + prog->pg_lovers = vers; + if (prog->pg_vers[vers]->vs_xdrsize > xdrsize) + xdrsize = prog->pg_vers[vers]->vs_xdrsize; + } + prog = prog->pg_next; + } + serv->sv_xdrsize = xdrsize; + INIT_LIST_HEAD(&serv->sv_tempsocks); + INIT_LIST_HEAD(&serv->sv_permsocks); + timer_setup(&serv->sv_temptimer, NULL, 0); + spin_lock_init(&serv->sv_lock); + + __svc_init_bc(serv); + + serv->sv_nrpools = npools; + serv->sv_pools = + kcalloc(serv->sv_nrpools, sizeof(struct svc_pool), + GFP_KERNEL); + if (!serv->sv_pools) { + kfree(serv); + return NULL; + } + + for (i = 0; i < serv->sv_nrpools; i++) { + struct svc_pool *pool = &serv->sv_pools[i]; + + dprintk("svc: initialising pool %u for %s\n", + i, serv->sv_name); + + pool->sp_id = i; + INIT_LIST_HEAD(&pool->sp_sockets); + INIT_LIST_HEAD(&pool->sp_all_threads); + spin_lock_init(&pool->sp_lock); + } + + return serv; +} + +/** + * svc_create - Create an RPC service + * @prog: the RPC program the new service will handle + * @bufsize: maximum message size for @prog + * @threadfn: a function to service RPC requests for @prog + * + * Returns an instantiated struct svc_serv object or NULL. + */ +struct svc_serv *svc_create(struct svc_program *prog, unsigned int bufsize, + int (*threadfn)(void *data)) +{ + return __svc_create(prog, bufsize, 1, threadfn); +} +EXPORT_SYMBOL_GPL(svc_create); + +/** + * svc_create_pooled - Create an RPC service with pooled threads + * @prog: the RPC program the new service will handle + * @bufsize: maximum message size for @prog + * @threadfn: a function to service RPC requests for @prog + * + * Returns an instantiated struct svc_serv object or NULL. + */ +struct svc_serv *svc_create_pooled(struct svc_program *prog, + unsigned int bufsize, + int (*threadfn)(void *data)) +{ + struct svc_serv *serv; + unsigned int npools = svc_pool_map_get(); + + serv = __svc_create(prog, bufsize, npools, threadfn); + if (!serv) + goto out_err; + return serv; +out_err: + svc_pool_map_put(npools); + return NULL; +} +EXPORT_SYMBOL_GPL(svc_create_pooled); + +/* + * Destroy an RPC service. Should be called with appropriate locking to + * protect sv_permsocks and sv_tempsocks. + */ +void +svc_destroy(struct kref *ref) +{ + struct svc_serv *serv = container_of(ref, struct svc_serv, sv_refcnt); + + dprintk("svc: svc_destroy(%s)\n", serv->sv_program->pg_name); + del_timer_sync(&serv->sv_temptimer); + + /* + * The last user is gone and thus all sockets have to be destroyed to + * the point. Check this. + */ + BUG_ON(!list_empty(&serv->sv_permsocks)); + BUG_ON(!list_empty(&serv->sv_tempsocks)); + + cache_clean_deferred(serv); + + svc_pool_map_put(serv->sv_nrpools); + + kfree(serv->sv_pools); + kfree(serv); +} +EXPORT_SYMBOL_GPL(svc_destroy); + +/* + * Allocate an RPC server's buffer space. + * We allocate pages and place them in rq_pages. + */ +static int +svc_init_buffer(struct svc_rqst *rqstp, unsigned int size, int node) +{ + unsigned int pages, arghi; + + /* bc_xprt uses fore channel allocated buffers */ + if (svc_is_backchannel(rqstp)) + return 1; + + pages = size / PAGE_SIZE + 1; /* extra page as we hold both request and reply. + * We assume one is at most one page + */ + arghi = 0; + WARN_ON_ONCE(pages > RPCSVC_MAXPAGES); + if (pages > RPCSVC_MAXPAGES) + pages = RPCSVC_MAXPAGES; + while (pages) { + struct page *p = alloc_pages_node(node, GFP_KERNEL, 0); + if (!p) + break; + rqstp->rq_pages[arghi++] = p; + pages--; + } + return pages == 0; +} + +/* + * Release an RPC server buffer + */ +static void +svc_release_buffer(struct svc_rqst *rqstp) +{ + unsigned int i; + + for (i = 0; i < ARRAY_SIZE(rqstp->rq_pages); i++) + if (rqstp->rq_pages[i]) + put_page(rqstp->rq_pages[i]); +} + +struct svc_rqst * +svc_rqst_alloc(struct svc_serv *serv, struct svc_pool *pool, int node) +{ + struct svc_rqst *rqstp; + + rqstp = kzalloc_node(sizeof(*rqstp), GFP_KERNEL, node); + if (!rqstp) + return rqstp; + + __set_bit(RQ_BUSY, &rqstp->rq_flags); + spin_lock_init(&rqstp->rq_lock); + rqstp->rq_server = serv; + rqstp->rq_pool = pool; + + rqstp->rq_scratch_page = alloc_pages_node(node, GFP_KERNEL, 0); + if (!rqstp->rq_scratch_page) + goto out_enomem; + + rqstp->rq_argp = kmalloc_node(serv->sv_xdrsize, GFP_KERNEL, node); + if (!rqstp->rq_argp) + goto out_enomem; + + rqstp->rq_resp = kmalloc_node(serv->sv_xdrsize, GFP_KERNEL, node); + if (!rqstp->rq_resp) + goto out_enomem; + + if (!svc_init_buffer(rqstp, serv->sv_max_mesg, node)) + goto out_enomem; + + return rqstp; +out_enomem: + svc_rqst_free(rqstp); + return NULL; +} +EXPORT_SYMBOL_GPL(svc_rqst_alloc); + +static struct svc_rqst * +svc_prepare_thread(struct svc_serv *serv, struct svc_pool *pool, int node) +{ + struct svc_rqst *rqstp; + + rqstp = svc_rqst_alloc(serv, pool, node); + if (!rqstp) + return ERR_PTR(-ENOMEM); + + svc_get(serv); + spin_lock_bh(&serv->sv_lock); + serv->sv_nrthreads += 1; + spin_unlock_bh(&serv->sv_lock); + + spin_lock_bh(&pool->sp_lock); + pool->sp_nrthreads++; + list_add_rcu(&rqstp->rq_all, &pool->sp_all_threads); + spin_unlock_bh(&pool->sp_lock); + return rqstp; +} + +/* + * Choose a pool in which to create a new thread, for svc_set_num_threads + */ +static inline struct svc_pool * +choose_pool(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state) +{ + if (pool != NULL) + return pool; + + return &serv->sv_pools[(*state)++ % serv->sv_nrpools]; +} + +/* + * Choose a thread to kill, for svc_set_num_threads + */ +static inline struct task_struct * +choose_victim(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state) +{ + unsigned int i; + struct task_struct *task = NULL; + + if (pool != NULL) { + spin_lock_bh(&pool->sp_lock); + } else { + /* choose a pool in round-robin fashion */ + for (i = 0; i < serv->sv_nrpools; i++) { + pool = &serv->sv_pools[--(*state) % serv->sv_nrpools]; + spin_lock_bh(&pool->sp_lock); + if (!list_empty(&pool->sp_all_threads)) + goto found_pool; + spin_unlock_bh(&pool->sp_lock); + } + return NULL; + } + +found_pool: + if (!list_empty(&pool->sp_all_threads)) { + struct svc_rqst *rqstp; + + /* + * Remove from the pool->sp_all_threads list + * so we don't try to kill it again. + */ + rqstp = list_entry(pool->sp_all_threads.next, struct svc_rqst, rq_all); + set_bit(RQ_VICTIM, &rqstp->rq_flags); + list_del_rcu(&rqstp->rq_all); + task = rqstp->rq_task; + } + spin_unlock_bh(&pool->sp_lock); + + return task; +} + +/* create new threads */ +static int +svc_start_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) +{ + struct svc_rqst *rqstp; + struct task_struct *task; + struct svc_pool *chosen_pool; + unsigned int state = serv->sv_nrthreads-1; + int node; + + do { + nrservs--; + chosen_pool = choose_pool(serv, pool, &state); + + node = svc_pool_map_get_node(chosen_pool->sp_id); + rqstp = svc_prepare_thread(serv, chosen_pool, node); + if (IS_ERR(rqstp)) + return PTR_ERR(rqstp); + + task = kthread_create_on_node(serv->sv_threadfn, rqstp, + node, "%s", serv->sv_name); + if (IS_ERR(task)) { + svc_exit_thread(rqstp); + return PTR_ERR(task); + } + + rqstp->rq_task = task; + if (serv->sv_nrpools > 1) + svc_pool_map_set_cpumask(task, chosen_pool->sp_id); + + svc_sock_update_bufs(serv); + wake_up_process(task); + } while (nrservs > 0); + + return 0; +} + +/* + * Create or destroy enough new threads to make the number + * of threads the given number. If `pool' is non-NULL, applies + * only to threads in that pool, otherwise round-robins between + * all pools. Caller must ensure that mutual exclusion between this and + * server startup or shutdown. + */ + +/* destroy old threads */ +static int +svc_stop_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) +{ + struct svc_rqst *rqstp; + struct task_struct *task; + unsigned int state = serv->sv_nrthreads-1; + + /* destroy old threads */ + do { + task = choose_victim(serv, pool, &state); + if (task == NULL) + break; + rqstp = kthread_data(task); + /* Did we lose a race to svo_function threadfn? */ + if (kthread_stop(task) == -EINTR) + svc_exit_thread(rqstp); + nrservs++; + } while (nrservs < 0); + return 0; +} + +int +svc_set_num_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) +{ + if (pool == NULL) { + nrservs -= serv->sv_nrthreads; + } else { + spin_lock_bh(&pool->sp_lock); + nrservs -= pool->sp_nrthreads; + spin_unlock_bh(&pool->sp_lock); + } + + if (nrservs > 0) + return svc_start_kthreads(serv, pool, nrservs); + if (nrservs < 0) + return svc_stop_kthreads(serv, pool, nrservs); + return 0; +} +EXPORT_SYMBOL_GPL(svc_set_num_threads); + +/** + * svc_rqst_replace_page - Replace one page in rq_pages[] + * @rqstp: svc_rqst with pages to replace + * @page: replacement page + * + * When replacing a page in rq_pages, batch the release of the + * replaced pages to avoid hammering the page allocator. + */ +void svc_rqst_replace_page(struct svc_rqst *rqstp, struct page *page) +{ + if (*rqstp->rq_next_page) { + if (!pagevec_space(&rqstp->rq_pvec)) + __pagevec_release(&rqstp->rq_pvec); + pagevec_add(&rqstp->rq_pvec, *rqstp->rq_next_page); + } + + get_page(page); + *(rqstp->rq_next_page++) = page; +} +EXPORT_SYMBOL_GPL(svc_rqst_replace_page); + +/* + * Called from a server thread as it's exiting. Caller must hold the "service + * mutex" for the service. + */ +void +svc_rqst_free(struct svc_rqst *rqstp) +{ + svc_release_buffer(rqstp); + if (rqstp->rq_scratch_page) + put_page(rqstp->rq_scratch_page); + kfree(rqstp->rq_resp); + kfree(rqstp->rq_argp); + kfree(rqstp->rq_auth_data); + kfree_rcu(rqstp, rq_rcu_head); +} +EXPORT_SYMBOL_GPL(svc_rqst_free); + +void +svc_exit_thread(struct svc_rqst *rqstp) +{ + struct svc_serv *serv = rqstp->rq_server; + struct svc_pool *pool = rqstp->rq_pool; + + spin_lock_bh(&pool->sp_lock); + pool->sp_nrthreads--; + if (!test_and_set_bit(RQ_VICTIM, &rqstp->rq_flags)) + list_del_rcu(&rqstp->rq_all); + spin_unlock_bh(&pool->sp_lock); + + spin_lock_bh(&serv->sv_lock); + serv->sv_nrthreads -= 1; + spin_unlock_bh(&serv->sv_lock); + svc_sock_update_bufs(serv); + + svc_rqst_free(rqstp); + + svc_put(serv); +} +EXPORT_SYMBOL_GPL(svc_exit_thread); + +/* + * Register an "inet" protocol family netid with the local + * rpcbind daemon via an rpcbind v4 SET request. + * + * No netconfig infrastructure is available in the kernel, so + * we map IP_ protocol numbers to netids by hand. + * + * Returns zero on success; a negative errno value is returned + * if any error occurs. + */ +static int __svc_rpcb_register4(struct net *net, const u32 program, + const u32 version, + const unsigned short protocol, + const unsigned short port) +{ + const struct sockaddr_in sin = { + .sin_family = AF_INET, + .sin_addr.s_addr = htonl(INADDR_ANY), + .sin_port = htons(port), + }; + const char *netid; + int error; + + switch (protocol) { + case IPPROTO_UDP: + netid = RPCBIND_NETID_UDP; + break; + case IPPROTO_TCP: + netid = RPCBIND_NETID_TCP; + break; + default: + return -ENOPROTOOPT; + } + + error = rpcb_v4_register(net, program, version, + (const struct sockaddr *)&sin, netid); + + /* + * User space didn't support rpcbind v4, so retry this + * registration request with the legacy rpcbind v2 protocol. + */ + if (error == -EPROTONOSUPPORT) + error = rpcb_register(net, program, version, protocol, port); + + return error; +} + +#if IS_ENABLED(CONFIG_IPV6) +/* + * Register an "inet6" protocol family netid with the local + * rpcbind daemon via an rpcbind v4 SET request. + * + * No netconfig infrastructure is available in the kernel, so + * we map IP_ protocol numbers to netids by hand. + * + * Returns zero on success; a negative errno value is returned + * if any error occurs. + */ +static int __svc_rpcb_register6(struct net *net, const u32 program, + const u32 version, + const unsigned short protocol, + const unsigned short port) +{ + const struct sockaddr_in6 sin6 = { + .sin6_family = AF_INET6, + .sin6_addr = IN6ADDR_ANY_INIT, + .sin6_port = htons(port), + }; + const char *netid; + int error; + + switch (protocol) { + case IPPROTO_UDP: + netid = RPCBIND_NETID_UDP6; + break; + case IPPROTO_TCP: + netid = RPCBIND_NETID_TCP6; + break; + default: + return -ENOPROTOOPT; + } + + error = rpcb_v4_register(net, program, version, + (const struct sockaddr *)&sin6, netid); + + /* + * User space didn't support rpcbind version 4, so we won't + * use a PF_INET6 listener. + */ + if (error == -EPROTONOSUPPORT) + error = -EAFNOSUPPORT; + + return error; +} +#endif /* IS_ENABLED(CONFIG_IPV6) */ + +/* + * Register a kernel RPC service via rpcbind version 4. + * + * Returns zero on success; a negative errno value is returned + * if any error occurs. + */ +static int __svc_register(struct net *net, const char *progname, + const u32 program, const u32 version, + const int family, + const unsigned short protocol, + const unsigned short port) +{ + int error = -EAFNOSUPPORT; + + switch (family) { + case PF_INET: + error = __svc_rpcb_register4(net, program, version, + protocol, port); + break; +#if IS_ENABLED(CONFIG_IPV6) + case PF_INET6: + error = __svc_rpcb_register6(net, program, version, + protocol, port); +#endif + } + + trace_svc_register(progname, version, family, protocol, port, error); + return error; +} + +int svc_rpcbind_set_version(struct net *net, + const struct svc_program *progp, + u32 version, int family, + unsigned short proto, + unsigned short port) +{ + return __svc_register(net, progp->pg_name, progp->pg_prog, + version, family, proto, port); + +} +EXPORT_SYMBOL_GPL(svc_rpcbind_set_version); + +int svc_generic_rpcbind_set(struct net *net, + const struct svc_program *progp, + u32 version, int family, + unsigned short proto, + unsigned short port) +{ + const struct svc_version *vers = progp->pg_vers[version]; + int error; + + if (vers == NULL) + return 0; + + if (vers->vs_hidden) { + trace_svc_noregister(progp->pg_name, version, proto, + port, family, 0); + return 0; + } + + /* + * Don't register a UDP port if we need congestion + * control. + */ + if (vers->vs_need_cong_ctrl && proto == IPPROTO_UDP) + return 0; + + error = svc_rpcbind_set_version(net, progp, version, + family, proto, port); + + return (vers->vs_rpcb_optnl) ? 0 : error; +} +EXPORT_SYMBOL_GPL(svc_generic_rpcbind_set); + +/** + * svc_register - register an RPC service with the local portmapper + * @serv: svc_serv struct for the service to register + * @net: net namespace for the service to register + * @family: protocol family of service's listener socket + * @proto: transport protocol number to advertise + * @port: port to advertise + * + * Service is registered for any address in the passed-in protocol family + */ +int svc_register(const struct svc_serv *serv, struct net *net, + const int family, const unsigned short proto, + const unsigned short port) +{ + struct svc_program *progp; + unsigned int i; + int error = 0; + + WARN_ON_ONCE(proto == 0 && port == 0); + if (proto == 0 && port == 0) + return -EINVAL; + + for (progp = serv->sv_program; progp; progp = progp->pg_next) { + for (i = 0; i < progp->pg_nvers; i++) { + + error = progp->pg_rpcbind_set(net, progp, i, + family, proto, port); + if (error < 0) { + printk(KERN_WARNING "svc: failed to register " + "%sv%u RPC service (errno %d).\n", + progp->pg_name, i, -error); + break; + } + } + } + + return error; +} + +/* + * If user space is running rpcbind, it should take the v4 UNSET + * and clear everything for this [program, version]. If user space + * is running portmap, it will reject the v4 UNSET, but won't have + * any "inet6" entries anyway. So a PMAP_UNSET should be sufficient + * in this case to clear all existing entries for [program, version]. + */ +static void __svc_unregister(struct net *net, const u32 program, const u32 version, + const char *progname) +{ + int error; + + error = rpcb_v4_register(net, program, version, NULL, ""); + + /* + * User space didn't support rpcbind v4, so retry this + * request with the legacy rpcbind v2 protocol. + */ + if (error == -EPROTONOSUPPORT) + error = rpcb_register(net, program, version, 0, 0); + + trace_svc_unregister(progname, version, error); +} + +/* + * All netids, bind addresses and ports registered for [program, version] + * are removed from the local rpcbind database (if the service is not + * hidden) to make way for a new instance of the service. + * + * The result of unregistration is reported via dprintk for those who want + * verification of the result, but is otherwise not important. + */ +static void svc_unregister(const struct svc_serv *serv, struct net *net) +{ + struct svc_program *progp; + unsigned long flags; + unsigned int i; + + clear_thread_flag(TIF_SIGPENDING); + + for (progp = serv->sv_program; progp; progp = progp->pg_next) { + for (i = 0; i < progp->pg_nvers; i++) { + if (progp->pg_vers[i] == NULL) + continue; + if (progp->pg_vers[i]->vs_hidden) + continue; + __svc_unregister(net, progp->pg_prog, i, progp->pg_name); + } + } + + spin_lock_irqsave(¤t->sighand->siglock, flags); + recalc_sigpending(); + spin_unlock_irqrestore(¤t->sighand->siglock, flags); +} + +/* + * dprintk the given error with the address of the client that caused it. + */ +#if IS_ENABLED(CONFIG_SUNRPC_DEBUG) +static __printf(2, 3) +void svc_printk(struct svc_rqst *rqstp, const char *fmt, ...) +{ + struct va_format vaf; + va_list args; + char buf[RPC_MAX_ADDRBUFLEN]; + + va_start(args, fmt); + + vaf.fmt = fmt; + vaf.va = &args; + + dprintk("svc: %s: %pV", svc_print_addr(rqstp, buf, sizeof(buf)), &vaf); + + va_end(args); +} +#else +static __printf(2,3) void svc_printk(struct svc_rqst *rqstp, const char *fmt, ...) {} +#endif + +__be32 +svc_generic_init_request(struct svc_rqst *rqstp, + const struct svc_program *progp, + struct svc_process_info *ret) +{ + const struct svc_version *versp = NULL; /* compiler food */ + const struct svc_procedure *procp = NULL; + + if (rqstp->rq_vers >= progp->pg_nvers ) + goto err_bad_vers; + versp = progp->pg_vers[rqstp->rq_vers]; + if (!versp) + goto err_bad_vers; + + /* + * Some protocol versions (namely NFSv4) require some form of + * congestion control. (See RFC 7530 section 3.1 paragraph 2) + * In other words, UDP is not allowed. We mark those when setting + * up the svc_xprt, and verify that here. + * + * The spec is not very clear about what error should be returned + * when someone tries to access a server that is listening on UDP + * for lower versions. RPC_PROG_MISMATCH seems to be the closest + * fit. + */ + if (versp->vs_need_cong_ctrl && rqstp->rq_xprt && + !test_bit(XPT_CONG_CTRL, &rqstp->rq_xprt->xpt_flags)) + goto err_bad_vers; + + if (rqstp->rq_proc >= versp->vs_nproc) + goto err_bad_proc; + rqstp->rq_procinfo = procp = &versp->vs_proc[rqstp->rq_proc]; + if (!procp) + goto err_bad_proc; + + /* Initialize storage for argp and resp */ + memset(rqstp->rq_argp, 0, procp->pc_argzero); + memset(rqstp->rq_resp, 0, procp->pc_ressize); + + /* Bump per-procedure stats counter */ + versp->vs_count[rqstp->rq_proc]++; + + ret->dispatch = versp->vs_dispatch; + return rpc_success; +err_bad_vers: + ret->mismatch.lovers = progp->pg_lovers; + ret->mismatch.hivers = progp->pg_hivers; + return rpc_prog_mismatch; +err_bad_proc: + return rpc_proc_unavail; +} +EXPORT_SYMBOL_GPL(svc_generic_init_request); + +/* + * Common routine for processing the RPC request. + */ +static int +svc_process_common(struct svc_rqst *rqstp, struct kvec *argv, struct kvec *resv) +{ + struct svc_program *progp; + const struct svc_procedure *procp = NULL; + struct svc_serv *serv = rqstp->rq_server; + struct svc_process_info process; + __be32 *statp; + u32 prog, vers; + __be32 rpc_stat; + int auth_res, rc; + __be32 *reply_statp; + + rpc_stat = rpc_success; + + if (argv->iov_len < 6*4) + goto err_short_len; + + /* Will be turned off by GSS integrity and privacy services */ + set_bit(RQ_SPLICE_OK, &rqstp->rq_flags); + /* Will be turned off only when NFSv4 Sessions are used */ + set_bit(RQ_USEDEFERRAL, &rqstp->rq_flags); + clear_bit(RQ_DROPME, &rqstp->rq_flags); + + svc_putu32(resv, rqstp->rq_xid); + + vers = svc_getnl(argv); + + /* First words of reply: */ + svc_putnl(resv, 1); /* REPLY */ + + if (vers != 2) /* RPC version number */ + goto err_bad_rpc; + + /* Save position in case we later decide to reject: */ + reply_statp = resv->iov_base + resv->iov_len; + + svc_putnl(resv, 0); /* ACCEPT */ + + rqstp->rq_prog = prog = svc_getnl(argv); /* program number */ + rqstp->rq_vers = svc_getnl(argv); /* version number */ + rqstp->rq_proc = svc_getnl(argv); /* procedure number */ + + for (progp = serv->sv_program; progp; progp = progp->pg_next) + if (prog == progp->pg_prog) + break; + + /* + * Decode auth data, and add verifier to reply buffer. + * We do this before anything else in order to get a decent + * auth verifier. + */ + auth_res = svc_authenticate(rqstp); + /* Also give the program a chance to reject this call: */ + if (auth_res == SVC_OK && progp) + auth_res = progp->pg_authenticate(rqstp); + if (auth_res != SVC_OK) + trace_svc_authenticate(rqstp, auth_res); + switch (auth_res) { + case SVC_OK: + break; + case SVC_GARBAGE: + goto err_garbage; + case SVC_SYSERR: + rpc_stat = rpc_system_err; + goto err_bad; + case SVC_DENIED: + goto err_bad_auth; + case SVC_CLOSE: + goto close; + case SVC_DROP: + goto dropit; + case SVC_COMPLETE: + goto sendit; + } + + if (progp == NULL) + goto err_bad_prog; + + rpc_stat = progp->pg_init_request(rqstp, progp, &process); + switch (rpc_stat) { + case rpc_success: + break; + case rpc_prog_unavail: + goto err_bad_prog; + case rpc_prog_mismatch: + goto err_bad_vers; + case rpc_proc_unavail: + goto err_bad_proc; + } + + procp = rqstp->rq_procinfo; + /* Should this check go into the dispatcher? */ + if (!procp || !procp->pc_func) + goto err_bad_proc; + + /* Syntactic check complete */ + serv->sv_stats->rpccnt++; + trace_svc_process(rqstp, progp->pg_name); + + /* Build the reply header. */ + statp = resv->iov_base +resv->iov_len; + svc_putnl(resv, RPC_SUCCESS); + + /* un-reserve some of the out-queue now that we have a + * better idea of reply size + */ + if (procp->pc_xdrressize) + svc_reserve_auth(rqstp, procp->pc_xdrressize<<2); + + /* Call the function that processes the request. */ + rc = process.dispatch(rqstp, statp); + if (procp->pc_release) + procp->pc_release(rqstp); + if (!rc) + goto dropit; + if (rqstp->rq_auth_stat != rpc_auth_ok) + goto err_bad_auth; + + /* Check RPC status result */ + if (*statp != rpc_success) + resv->iov_len = ((void*)statp) - resv->iov_base + 4; + + if (procp->pc_encode == NULL) + goto dropit; + + sendit: + if (svc_authorise(rqstp)) + goto close_xprt; + return 1; /* Caller can now send it */ + + dropit: + svc_authorise(rqstp); /* doesn't hurt to call this twice */ + dprintk("svc: svc_process dropit\n"); + return 0; + + close: + svc_authorise(rqstp); +close_xprt: + if (rqstp->rq_xprt && test_bit(XPT_TEMP, &rqstp->rq_xprt->xpt_flags)) + svc_xprt_close(rqstp->rq_xprt); + dprintk("svc: svc_process close\n"); + return 0; + +err_short_len: + svc_printk(rqstp, "short len %zd, dropping request\n", + argv->iov_len); + goto close_xprt; + +err_bad_rpc: + serv->sv_stats->rpcbadfmt++; + svc_putnl(resv, 1); /* REJECT */ + svc_putnl(resv, 0); /* RPC_MISMATCH */ + svc_putnl(resv, 2); /* Only RPCv2 supported */ + svc_putnl(resv, 2); + goto sendit; + +err_bad_auth: + dprintk("svc: authentication failed (%d)\n", + be32_to_cpu(rqstp->rq_auth_stat)); + serv->sv_stats->rpcbadauth++; + /* Restore write pointer to location of accept status: */ + xdr_ressize_check(rqstp, reply_statp); + svc_putnl(resv, 1); /* REJECT */ + svc_putnl(resv, 1); /* AUTH_ERROR */ + svc_putu32(resv, rqstp->rq_auth_stat); /* status */ + goto sendit; + +err_bad_prog: + dprintk("svc: unknown program %d\n", prog); + serv->sv_stats->rpcbadfmt++; + svc_putnl(resv, RPC_PROG_UNAVAIL); + goto sendit; + +err_bad_vers: + svc_printk(rqstp, "unknown version (%d for prog %d, %s)\n", + rqstp->rq_vers, rqstp->rq_prog, progp->pg_name); + + serv->sv_stats->rpcbadfmt++; + svc_putnl(resv, RPC_PROG_MISMATCH); + svc_putnl(resv, process.mismatch.lovers); + svc_putnl(resv, process.mismatch.hivers); + goto sendit; + +err_bad_proc: + svc_printk(rqstp, "unknown procedure (%d)\n", rqstp->rq_proc); + + serv->sv_stats->rpcbadfmt++; + svc_putnl(resv, RPC_PROC_UNAVAIL); + goto sendit; + +err_garbage: + svc_printk(rqstp, "failed to decode args\n"); + + rpc_stat = rpc_garbage_args; +err_bad: + serv->sv_stats->rpcbadfmt++; + svc_putnl(resv, ntohl(rpc_stat)); + goto sendit; +} + +/* + * Process the RPC request. + */ +int +svc_process(struct svc_rqst *rqstp) +{ + struct kvec *argv = &rqstp->rq_arg.head[0]; + struct kvec *resv = &rqstp->rq_res.head[0]; + __be32 dir; + +#if IS_ENABLED(CONFIG_FAIL_SUNRPC) + if (!fail_sunrpc.ignore_server_disconnect && + should_fail(&fail_sunrpc.attr, 1)) + svc_xprt_deferred_close(rqstp->rq_xprt); +#endif + + /* + * Setup response xdr_buf. + * Initially it has just one page + */ + rqstp->rq_next_page = &rqstp->rq_respages[1]; + resv->iov_base = page_address(rqstp->rq_respages[0]); + resv->iov_len = 0; + rqstp->rq_res.pages = rqstp->rq_next_page; + rqstp->rq_res.len = 0; + rqstp->rq_res.page_base = 0; + rqstp->rq_res.page_len = 0; + rqstp->rq_res.buflen = PAGE_SIZE; + rqstp->rq_res.tail[0].iov_base = NULL; + rqstp->rq_res.tail[0].iov_len = 0; + + dir = svc_getu32(argv); + if (dir != rpc_call) + goto out_baddir; + if (!svc_process_common(rqstp, argv, resv)) + goto out_drop; + return svc_send(rqstp); + +out_baddir: + svc_printk(rqstp, "bad direction 0x%08x, dropping request\n", + be32_to_cpu(dir)); + rqstp->rq_server->sv_stats->rpcbadfmt++; +out_drop: + svc_drop(rqstp); + return 0; +} +EXPORT_SYMBOL_GPL(svc_process); + +#if defined(CONFIG_SUNRPC_BACKCHANNEL) +/* + * Process a backchannel RPC request that arrived over an existing + * outbound connection + */ +int +bc_svc_process(struct svc_serv *serv, struct rpc_rqst *req, + struct svc_rqst *rqstp) +{ + struct kvec *argv = &rqstp->rq_arg.head[0]; + struct kvec *resv = &rqstp->rq_res.head[0]; + struct rpc_task *task; + int proc_error; + int error; + + dprintk("svc: %s(%p)\n", __func__, req); + + /* Build the svc_rqst used by the common processing routine */ + rqstp->rq_xid = req->rq_xid; + rqstp->rq_prot = req->rq_xprt->prot; + rqstp->rq_server = serv; + rqstp->rq_bc_net = req->rq_xprt->xprt_net; + + rqstp->rq_addrlen = sizeof(req->rq_xprt->addr); + memcpy(&rqstp->rq_addr, &req->rq_xprt->addr, rqstp->rq_addrlen); + memcpy(&rqstp->rq_arg, &req->rq_rcv_buf, sizeof(rqstp->rq_arg)); + memcpy(&rqstp->rq_res, &req->rq_snd_buf, sizeof(rqstp->rq_res)); + + /* Adjust the argument buffer length */ + rqstp->rq_arg.len = req->rq_private_buf.len; + if (rqstp->rq_arg.len <= rqstp->rq_arg.head[0].iov_len) { + rqstp->rq_arg.head[0].iov_len = rqstp->rq_arg.len; + rqstp->rq_arg.page_len = 0; + } else if (rqstp->rq_arg.len <= rqstp->rq_arg.head[0].iov_len + + rqstp->rq_arg.page_len) + rqstp->rq_arg.page_len = rqstp->rq_arg.len - + rqstp->rq_arg.head[0].iov_len; + else + rqstp->rq_arg.len = rqstp->rq_arg.head[0].iov_len + + rqstp->rq_arg.page_len; + + /* reset result send buffer "put" position */ + resv->iov_len = 0; + + /* + * Skip the next two words because they've already been + * processed in the transport + */ + svc_getu32(argv); /* XID */ + svc_getnl(argv); /* CALLDIR */ + + /* Parse and execute the bc call */ + proc_error = svc_process_common(rqstp, argv, resv); + + atomic_dec(&req->rq_xprt->bc_slot_count); + if (!proc_error) { + /* Processing error: drop the request */ + xprt_free_bc_request(req); + error = -EINVAL; + goto out; + } + /* Finally, send the reply synchronously */ + memcpy(&req->rq_snd_buf, &rqstp->rq_res, sizeof(req->rq_snd_buf)); + task = rpc_run_bc_task(req); + if (IS_ERR(task)) { + error = PTR_ERR(task); + goto out; + } + + WARN_ON_ONCE(atomic_read(&task->tk_count) != 1); + error = task->tk_status; + rpc_put_task(task); + +out: + dprintk("svc: %s(), error=%d\n", __func__, error); + return error; +} +EXPORT_SYMBOL_GPL(bc_svc_process); +#endif /* CONFIG_SUNRPC_BACKCHANNEL */ + +/** + * svc_max_payload - Return transport-specific limit on the RPC payload + * @rqstp: RPC transaction context + * + * Returns the maximum number of payload bytes the current transport + * allows. + */ +u32 svc_max_payload(const struct svc_rqst *rqstp) +{ + u32 max = rqstp->rq_xprt->xpt_class->xcl_max_payload; + + if (rqstp->rq_server->sv_max_payload < max) + max = rqstp->rq_server->sv_max_payload; + return max; +} +EXPORT_SYMBOL_GPL(svc_max_payload); + +/** + * svc_proc_name - Return RPC procedure name in string form + * @rqstp: svc_rqst to operate on + * + * Return value: + * Pointer to a NUL-terminated string + */ +const char *svc_proc_name(const struct svc_rqst *rqstp) +{ + if (rqstp && rqstp->rq_procinfo) + return rqstp->rq_procinfo->pc_name; + return "unknown"; +} + + +/** + * svc_encode_result_payload - mark a range of bytes as a result payload + * @rqstp: svc_rqst to operate on + * @offset: payload's byte offset in rqstp->rq_res + * @length: size of payload, in bytes + * + * Returns zero on success, or a negative errno if a permanent + * error occurred. + */ +int svc_encode_result_payload(struct svc_rqst *rqstp, unsigned int offset, + unsigned int length) +{ + return rqstp->rq_xprt->xpt_ops->xpo_result_payload(rqstp, offset, + length); +} +EXPORT_SYMBOL_GPL(svc_encode_result_payload); + +/** + * svc_fill_write_vector - Construct data argument for VFS write call + * @rqstp: svc_rqst to operate on + * @payload: xdr_buf containing only the write data payload + * + * Fills in rqstp::rq_vec, and returns the number of elements. + */ +unsigned int svc_fill_write_vector(struct svc_rqst *rqstp, + struct xdr_buf *payload) +{ + struct page **pages = payload->pages; + struct kvec *first = payload->head; + struct kvec *vec = rqstp->rq_vec; + size_t total = payload->len; + unsigned int i; + + /* Some types of transport can present the write payload + * entirely in rq_arg.pages. In this case, @first is empty. + */ + i = 0; + if (first->iov_len) { + vec[i].iov_base = first->iov_base; + vec[i].iov_len = min_t(size_t, total, first->iov_len); + total -= vec[i].iov_len; + ++i; + } + + while (total) { + vec[i].iov_base = page_address(*pages); + vec[i].iov_len = min_t(size_t, total, PAGE_SIZE); + total -= vec[i].iov_len; + ++i; + ++pages; + } + + WARN_ON_ONCE(i > ARRAY_SIZE(rqstp->rq_vec)); + return i; +} +EXPORT_SYMBOL_GPL(svc_fill_write_vector); + +/** + * svc_fill_symlink_pathname - Construct pathname argument for VFS symlink call + * @rqstp: svc_rqst to operate on + * @first: buffer containing first section of pathname + * @p: buffer containing remaining section of pathname + * @total: total length of the pathname argument + * + * The VFS symlink API demands a NUL-terminated pathname in mapped memory. + * Returns pointer to a NUL-terminated string, or an ERR_PTR. Caller must free + * the returned string. + */ +char *svc_fill_symlink_pathname(struct svc_rqst *rqstp, struct kvec *first, + void *p, size_t total) +{ + size_t len, remaining; + char *result, *dst; + + result = kmalloc(total + 1, GFP_KERNEL); + if (!result) + return ERR_PTR(-ESERVERFAULT); + + dst = result; + remaining = total; + + len = min_t(size_t, total, first->iov_len); + if (len) { + memcpy(dst, first->iov_base, len); + dst += len; + remaining -= len; + } + + if (remaining) { + len = min_t(size_t, remaining, PAGE_SIZE); + memcpy(dst, p, len); + dst += len; + } + + *dst = '\0'; + + /* Sanity check: Linux doesn't allow the pathname argument to + * contain a NUL byte. + */ + if (strlen(result) != total) { + kfree(result); + return ERR_PTR(-EINVAL); + } + return result; +} +EXPORT_SYMBOL_GPL(svc_fill_symlink_pathname); |