// SPDX-License-Identifier: GPL-2.0-only/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com * Copyright (c) 2016 Facebook */#include <linux/bpf.h>#include <linux/btf.h>#include <linux/jhash.h>#include <linux/filter.h>#include <linux/rculist_nulls.h>#include <linux/random.h>#include <uapi/linux/btf.h>#include "percpu_freelist.h"#include "bpf_lru_list.h"#include "map_in_map.h" #define HTAB_CREATE_FLAG_MASK \ (BPF_F_NO_PREALLOC | BPF_F_NO_COMMON_LRU | BPF_F_NUMA_NODE | \ BPF_F_ACCESS_MASK | BPF_F_ZERO_SEED) #define BATCH_OPS(_name) \ .map_lookup_batch = \ _name##_map_lookup_batch, \ .map_lookup_and_delete_batch = \ _name##_map_lookup_and_delete_batch, \ .map_update_batch = \ generic_map_update_batch, \ .map_delete_batch = \ generic_map_delete_batch /* * The bucket lock has two protection scopes: * * 1) Serializing concurrent operations from BPF programs on differrent * CPUs * * 2) Serializing concurrent operations from BPF programs and sys_bpf() * * BPF programs can execute in any context including perf, kprobes and * tracing. As there are almost no limits where perf, kprobes and tracing * can be invoked from the lock operations need to be protected against * deadlocks. Deadlocks can be caused by recursion and by an invocation in * the lock held section when functions which acquire this lock are invoked * from sys_bpf(). BPF recursion is prevented by incrementing the per CPU * variable bpf_prog_active, which prevents BPF programs attached to perf * events, kprobes and tracing to be invoked before the prior invocation * from one of these contexts completed. sys_bpf() uses the same mechanism * by pinning the task to the current CPU and incrementing the recursion * protection accross the map operation. * * This has subtle implications on PREEMPT_RT. PREEMPT_RT forbids certain * operations like memory allocations (even with GFP_ATOMIC) from atomic * contexts. This is required because even with GFP_ATOMIC the memory * allocator calls into code pathes which acquire locks with long held lock * sections. To ensure the deterministic behaviour these locks are regular * spinlocks, which are converted to 'sleepable' spinlocks on RT. The only * true atomic contexts on an RT kernel are the low level hardware * handling, scheduling, low level interrupt handling, NMIs etc. None of * these contexts should ever do memory allocations. * * As regular device interrupt handlers and soft interrupts are forced into * thread context, the existing code which does * spin_lock*(); alloc(GPF_ATOMIC); spin_unlock*(); * just works. * * In theory the BPF locks could be converted to regular spinlocks as well, * but the bucket locks and percpu_freelist locks can be taken from * arbitrary contexts (perf, kprobes, tracepoints) which are required to be * atomic contexts even on RT. These mechanisms require preallocated maps, * so there is no need to invoke memory allocations within the lock held * sections. * * BPF maps which need dynamic allocation are only used from (forced) * thread context on RT and can therefore use regular spinlocks which in * turn allows to invoke memory allocations from the lock held section. * * On a non RT kernel this distinction is neither possible nor required. * spinlock maps to raw_spinlock and the extra code is optimized out by the * compiler. */struct bucket { struct hlist_nulls_head head; union { raw_spinlock_t raw_lock; spinlock_t lock; };}; struct bpf_htab { struct bpf_map map; struct bucket *buckets; void *elems; union { struct pcpu_freelist freelist; struct bpf_lru lru; }; struct htab_elem *__percpu *extra_elems; atomic_t count; /* number of elements in this hashtable */ u32 n_buckets; /* number of hash buckets */ u32 elem_size; /* size of each element in bytes */ u32 hashrnd;}; /* each htab element is struct htab_elem + key + value */struct htab_elem { union { struct hlist_nulls_node hash_node; struct { void *padding; union { struct bpf_htab *htab; struct pcpu_freelist_node fnode; struct htab_elem *batch_flink; }; }; }; union { struct rcu_head rcu; struct bpf_lru_node lru_node; }; u32 hash; char key[] __aligned(8);}; static inline bool htab_is_prealloc(const struct bpf_htab *htab){ return !(htab->map.map_flags & BPF_F_NO_PREALLOC);} static inline bool htab_use_raw_lock(const struct bpf_htab *htab){ return (!IS_ENABLED(CONFIG_PREEMPT_RT) || htab_is_prealloc(htab));} static void htab_init_buckets(struct bpf_htab *htab){ unsigned i; for (i = 0; i < htab->n_buckets; i++) { INIT_HLIST_NULLS_HEAD(&htab->buckets[i].head, i); if (htab_use_raw_lock(htab)) raw_spin_lock_init(&htab->buckets[i].raw_lock); else spin_lock_init(&htab->buckets[i].lock); }} static inline unsigned long htab_lock_bucket(const struct bpf_htab *htab, struct bucket *b){ unsigned long flags; if (htab_use_raw_lock(htab)) raw_spin_lock_irqsave(&b->raw_lock, flags); else spin_lock_irqsave(&b->lock, flags); return flags;} static inline void htab_unlock_bucket(const struct bpf_htab *htab, struct bucket *b, unsigned long flags){ if (htab_use_raw_lock(htab)) raw_spin_unlock_irqrestore(&b->raw_lock, flags); else spin_unlock_irqrestore(&b->lock, flags);} static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node); static bool htab_is_lru(const struct bpf_htab *htab){ return htab->map.map_type == BPF_MAP_TYPE_LRU_HASH || htab->map.map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH;} static bool htab_is_percpu(const struct bpf_htab *htab){ return htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH || htab->map.map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH;} static inline void htab_elem_set_ptr(struct htab_elem *l, u32 key_size, void __percpu *pptr){ *(void __percpu **)(l->key + key_size) = pptr;} static inline void __percpu *htab_elem_get_ptr(struct htab_elem *l, u32 key_size){ return *(void __percpu **)(l->key + key_size);} static void *fd_htab_map_get_ptr(const struct bpf_map *map, struct htab_elem *l){ return *(void **)(l->key + roundup(map->key_size, 8));} static struct htab_elem *get_htab_elem(struct bpf_htab *htab, int i){ return (struct htab_elem *) (htab->elems + i * htab->elem_size);} static void htab_free_elems(struct bpf_htab *htab){ int i; if (!htab_is_percpu(htab)) goto free_elems; for (i = 0; i < htab->map.max_entries; i++) { void __percpu *pptr; pptr = htab_elem_get_ptr(get_htab_elem(htab, i), htab->map.key_size); free_percpu(pptr); cond_resched(); }free_elems: bpf_map_area_free(htab->elems);} /* The LRU list has a lock (lru_lock). Each htab bucket has a lock * (bucket_lock). If both locks need to be acquired together, the lock * order is always lru_lock -> bucket_lock and this only happens in * bpf_lru_list.c logic. For example, certain code path of * bpf_lru_pop_free(), which is called by function prealloc_lru_pop(), * will acquire lru_lock first followed by acquiring bucket_lock. * * In hashtab.c, to avoid deadlock, lock acquisition of * bucket_lock followed by lru_lock is not allowed. In such cases, * bucket_lock needs to be released first before acquiring lru_lock. */static struct htab_elem *prealloc_lru_pop(struct bpf_htab *htab, void *key, u32 hash){ struct bpf_lru_node *node = bpf_lru_pop_free(&htab->lru, hash); struct htab_elem *l; if (node) { l = container_of(node, struct htab_elem, lru_node); memcpy(l->key, key, htab->map.key_size); return l; } return NULL;} static int prealloc_init(struct bpf_htab *htab){ u32 num_entries = htab->map.max_entries; int err = -ENOMEM, i; if (!htab_is_percpu(htab) && !htab_is_lru(htab)) num_entries += num_possible_cpus(); htab->elems = bpf_map_area_alloc(htab->elem_size * num_entries, htab->map.numa_node); if (!htab->elems) return -ENOMEM; if (!htab_is_percpu(htab)) goto skip_percpu_elems; for (i = 0; i < num_entries; i++) { u32 size = round_up(htab->map.value_size, 8); void __percpu *pptr; pptr = __alloc_percpu_gfp(size, 8, GFP_USER | __GFP_NOWARN); if (!pptr) goto free_elems; htab_elem_set_ptr(get_htab_elem(htab, i), htab->map.key_size, pptr); cond_resched(); } skip_percpu_elems: if (htab_is_lru(htab)) err = bpf_lru_init(&htab->lru, htab->map.map_flags & BPF_F_NO_COMMON_LRU, offsetof(struct htab_elem, hash) - offsetof(struct htab_elem, lru_node), htab_lru_map_delete_node, htab); else err = pcpu_freelist_init(&htab->freelist); if (err) goto free_elems; if (htab_is_lru(htab)) bpf_lru_populate(&htab->lru, htab->elems, offsetof(struct htab_elem, lru_node), htab->elem_size, num_entries); else pcpu_freelist_populate(&htab->freelist, htab->elems + offsetof(struct htab_elem, fnode), htab->elem_size, num_entries); return 0; free_elems: htab_free_elems(htab); return err;} static void prealloc_destroy(struct bpf_htab *htab){ htab_free_elems(htab); if (htab_is_lru(htab)) bpf_lru_destroy(&htab->lru); else pcpu_freelist_destroy(&htab->freelist);} static int alloc_extra_elems(struct bpf_htab *htab){ struct htab_elem *__percpu *pptr, *l_new; struct pcpu_freelist_node *l; int cpu; pptr = __alloc_percpu_gfp(sizeof(struct htab_elem *), 8, GFP_USER | __GFP_NOWARN); if (!pptr) return -ENOMEM; for_each_possible_cpu(cpu) { l = pcpu_freelist_pop(&htab->freelist); /* pop will succeed, since prealloc_init() * preallocated extra num_possible_cpus elements */ l_new = container_of(l, struct htab_elem, fnode); *per_cpu_ptr(pptr, cpu) = l_new; } htab->extra_elems = pptr; return 0;} /* Called from syscall */static int htab_map_alloc_check(union bpf_attr *attr){ bool percpu = (attr->map_type == BPF_MAP_TYPE_PERCPU_HASH || attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH); bool lru = (attr->map_type == BPF_MAP_TYPE_LRU_HASH || attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH); /* percpu_lru means each cpu has its own LRU list. * it is different from BPF_MAP_TYPE_PERCPU_HASH where * the map's value itself is percpu. percpu_lru has * nothing to do with the map's value. */ bool percpu_lru = (attr->map_flags & BPF_F_NO_COMMON_LRU); bool prealloc = !(attr->map_flags & BPF_F_NO_PREALLOC); bool zero_seed = (attr->map_flags & BPF_F_ZERO_SEED); int numa_node = bpf_map_attr_numa_node(attr); BUILD_BUG_ON(offsetof(struct htab_elem, htab) != offsetof(struct htab_elem, hash_node.pprev)); BUILD_BUG_ON(offsetof(struct htab_elem, fnode.next) != offsetof(struct htab_elem, hash_node.pprev)); if (lru && !bpf_capable()) /* LRU implementation is much complicated than other * maps. Hence, limit to CAP_BPF. */ return -EPERM; if (zero_seed && !capable(CAP_SYS_ADMIN)) /* Guard against local DoS, and discourage production use. */ return -EPERM; if (attr->map_flags & ~HTAB_CREATE_FLAG_MASK || !bpf_map_flags_access_ok(attr->map_flags)) return -EINVAL; if (!lru && percpu_lru) return -EINVAL; if (lru && !prealloc) return -ENOTSUPP; if (numa_node != NUMA_NO_NODE && (percpu || percpu_lru)) return -EINVAL; /* check sanity of attributes. * value_size == 0 may be allowed in the future to use map as a set */ if (attr->max_entries == 0 || attr->key_size == 0 || attr->value_size == 0) return -EINVAL; if (attr->key_size > MAX_BPF_STACK) /* eBPF programs initialize keys on stack, so they cannot be * larger than max stack size */ return -E2BIG; if (attr->value_size >= KMALLOC_MAX_SIZE - MAX_BPF_STACK - sizeof(struct htab_elem)) /* if value_size is bigger, the user space won't be able to * access the elements via bpf syscall. This check also makes * sure that the elem_size doesn't overflow and it's * kmalloc-able later in htab_map_update_elem() */ return -E2BIG; return 0;} static struct bpf_map *htab_map_alloc(union bpf_attr *attr){ bool percpu = (attr->map_type == BPF_MAP_TYPE_PERCPU_HASH || attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH); bool lru = (attr->map_type == BPF_MAP_TYPE_LRU_HASH || attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH); /* percpu_lru means each cpu has its own LRU list. * it is different from BPF_MAP_TYPE_PERCPU_HASH where * the map's value itself is percpu. percpu_lru has * nothing to do with the map's value. */ bool percpu_lru = (attr->map_flags & BPF_F_NO_COMMON_LRU); bool prealloc = !(attr->map_flags & BPF_F_NO_PREALLOC); struct bpf_htab *htab; u64 cost; int err; htab = kzalloc(sizeof(*htab), GFP_USER); if (!htab) return ERR_PTR(-ENOMEM); bpf_map_init_from_attr(&htab->map, attr); if (percpu_lru) { /* ensure each CPU's lru list has >=1 elements. * since we are at it, make each lru list has the same * number of elements. */ htab->map.max_entries = roundup(attr->max_entries, num_possible_cpus()); if (htab->map.max_entries < attr->max_entries) htab->map.max_entries = rounddown(attr->max_entries, num_possible_cpus()); } /* hash table size must be power of 2 */ htab->n_buckets = roundup_pow_of_two(htab->map.max_entries); htab->elem_size = sizeof(struct htab_elem) + round_up(htab->map.key_size, 8); if (percpu) htab->elem_size += sizeof(void *); else htab->elem_size += round_up(htab->map.value_size, 8); err = -E2BIG; /* prevent zero size kmalloc and check for u32 overflow */ if (htab->n_buckets == 0 || htab->n_buckets > U32_MAX / sizeof(struct bucket)) goto free_htab; cost = (u64) htab->n_buckets * sizeof(struct bucket) + (u64) htab->elem_size * htab->map.max_entries; if (percpu) cost += (u64) round_up(htab->map.value_size, 8) * num_possible_cpus() * htab->map.max_entries; else cost += (u64) htab->elem_size * num_possible_cpus(); /* if map size is larger than memlock limit, reject it */ err = bpf_map_charge_init(&htab->map.memory, cost); if (err) goto free_htab; err = -ENOMEM; htab->buckets = bpf_map_area_alloc(htab->n_buckets * sizeof(struct bucket), htab->map.numa_node); if (!htab->buckets) goto free_charge; if (htab->map.map_flags & BPF_F_ZERO_SEED) htab->hashrnd = 0; else htab->hashrnd = get_random_int(); htab_init_buckets(htab); if (prealloc) { err = prealloc_init(htab); if (err) goto free_buckets; if (!percpu && !lru) { /* lru itself can remove the least used element, so * there is no need for an extra elem during map_update. */ err = alloc_extra_elems(htab); if (err) goto free_prealloc;Lines 1–500 of 2115. 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// SPDX-License-Identifier: GPL-2.0-only /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com * Copyright (c) 2016 Facebook */ #include <linux/bpf.h> #include <linux/btf.h> #include <linux/jhash.h> #include <linux/filter.h> #include <linux/rculist_nulls.h> #include <linux/random.h> #include <uapi/linux/btf.h> #include "percpu_freelist.h" #include "bpf_lru_list.h" #include "map_in_map.h" #define HTAB_CREATE_FLAG_MASK \ (BPF_F_NO_PREALLOC | BPF_F_NO_COMMON_LRU | BPF_F_NUMA_NODE | \ BPF_F_ACCESS_MASK | BPF_F_ZERO_SEED) #define BATCH_OPS(_name) \ .map_lookup_batch = \ _name##_map_lookup_batch, \ .map_lookup_and_delete_batch = \ _name##_map_lookup_and_delete_batch, \ .map_update_batch = \ generic_map_update_batch, \ .map_delete_batch = \ generic_map_delete_batch /* * The bucket lock has two protection scopes: * * 1) Serializing concurrent operations from BPF programs on differrent * CPUs * * 2) Serializing concurrent operations from BPF programs and sys_bpf() * * BPF programs can execute in any context including perf, kprobes and * tracing. As there are almost no limits where perf, kprobes and tracing * can be invoked from the lock operations need to be protected against * deadlocks. Deadlocks can be caused by recursion and by an invocation in * the lock held section when functions which acquire this lock are invoked * from sys_bpf(). BPF recursion is prevented by incrementing the per CPU * variable bpf_prog_active, which prevents BPF programs attached to perf * events, kprobes and tracing to be invoked before the prior invocation * from one of these contexts completed. sys_bpf() uses the same mechanism * by pinning the task to the current CPU and incrementing the recursion * protection accross the map operation. * * This has subtle implications on PREEMPT_RT. PREEMPT_RT forbids certain * operations like memory allocations (even with GFP_ATOMIC) from atomic * contexts. This is required because even with GFP_ATOMIC the memory * allocator calls into code pathes which acquire locks with long held lock * sections. To ensure the deterministic behaviour these locks are regular * spinlocks, which are converted to 'sleepable' spinlocks on RT. The only * true atomic contexts on an RT kernel are the low level hardware * handling, scheduling, low level interrupt handling, NMIs etc. None of * these contexts should ever do memory allocations. * * As regular device interrupt handlers and soft interrupts are forced into * thread context, the existing code which does * spin_lock*(); alloc(GPF_ATOMIC); spin_unlock*(); * just works. * * In theory the BPF locks could be converted to regular spinlocks as well, * but the bucket locks and percpu_freelist locks can be taken from * arbitrary contexts (perf, kprobes, tracepoints) which are required to be * atomic contexts even on RT. These mechanisms require preallocated maps, * so there is no need to invoke memory allocations within the lock held * sections. * * BPF maps which need dynamic allocation are only used from (forced) * thread context on RT and can therefore use regular spinlocks which in * turn allows to invoke memory allocations from the lock held section. * * On a non RT kernel this distinction is neither possible nor required. * spinlock maps to raw_spinlock and the extra code is optimized out by the * compiler. */ struct bucket { struct hlist_nulls_head head; union { raw_spinlock_t raw_lock; spinlock_t lock; }; }; struct bpf_htab { struct bpf_map map; struct bucket *buckets; void *elems; union { struct pcpu_freelist freelist; struct bpf_lru lru; }; struct htab_elem *__percpu *extra_elems; atomic_t count; /* number of elements in this hashtable */ u32 n_buckets; /* number of hash buckets */ u32 elem_size; /* size of each element in bytes */ u32 hashrnd; }; /* each htab element is struct htab_elem + key + value */ struct htab_elem { union { struct hlist_nulls_node hash_node; struct { void *padding; union { struct bpf_htab *htab; struct pcpu_freelist_node fnode; struct htab_elem *batch_flink; }; }; }; union { struct rcu_head rcu; struct bpf_lru_node lru_node; }; u32 hash; char key[] __aligned(8); }; static inline bool htab_is_prealloc(const struct bpf_htab *htab) { return !(htab->map.map_flags & BPF_F_NO_PREALLOC); } static inline bool htab_use_raw_lock(const struct bpf_htab *htab) { return (!IS_ENABLED(CONFIG_PREEMPT_RT) || htab_is_prealloc(htab)); } static void htab_init_buckets(struct bpf_htab *htab) { unsigned i; for (i = 0; i < htab->n_buckets; i++) { INIT_HLIST_NULLS_HEAD(&htab->buckets[i].head, i); if (htab_use_raw_lock(htab)) raw_spin_lock_init(&htab->buckets[i].raw_lock); else spin_lock_init(&htab->buckets[i].lock); } } static inline unsigned long htab_lock_bucket(const struct bpf_htab *htab, struct bucket *b) { unsigned long flags; if (htab_use_raw_lock(htab)) raw_spin_lock_irqsave(&b->raw_lock, flags); else spin_lock_irqsave(&b->lock, flags); return flags; } static inline void htab_unlock_bucket(const struct bpf_htab *htab, struct bucket *b, unsigned long flags) { if (htab_use_raw_lock(htab)) raw_spin_unlock_irqrestore(&b->raw_lock, flags); else spin_unlock_irqrestore(&b->lock, flags); } static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node); static bool htab_is_lru(const struct bpf_htab *htab) { return htab->map.map_type == BPF_MAP_TYPE_LRU_HASH || htab->map.map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH; } static bool htab_is_percpu(const struct bpf_htab *htab) { return htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH || htab->map.map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH; } static inline void htab_elem_set_ptr(struct htab_elem *l, u32 key_size, void __percpu *pptr) { *(void __percpu **)(l->key + key_size) = pptr; } static inline void __percpu *htab_elem_get_ptr(struct htab_elem *l, u32 key_size) { return *(void __percpu **)(l->key + key_size); } static void *fd_htab_map_get_ptr(const struct bpf_map *map, struct htab_elem *l) { return *(void **)(l->key + roundup(map->key_size, 8)); } static struct htab_elem *get_htab_elem(struct bpf_htab *htab, int i) { return (struct htab_elem *) (htab->elems + i * htab->elem_size); } static void htab_free_elems(struct bpf_htab *htab) { int i; if (!htab_is_percpu(htab)) goto free_elems; for (i = 0; i < htab->map.max_entries; i++) { void __percpu *pptr; pptr = htab_elem_get_ptr(get_htab_elem(htab, i), htab->map.key_size); free_percpu(pptr); cond_resched(); } free_elems: bpf_map_area_free(htab->elems); } /* The LRU list has a lock (lru_lock). Each htab bucket has a lock * (bucket_lock). If both locks need to be acquired together, the lock * order is always lru_lock -> bucket_lock and this only happens in * bpf_lru_list.c logic. For example, certain code path of * bpf_lru_pop_free(), which is called by function prealloc_lru_pop(), * will acquire lru_lock first followed by acquiring bucket_lock. * * In hashtab.c, to avoid deadlock, lock acquisition of * bucket_lock followed by lru_lock is not allowed. In such cases, * bucket_lock needs to be released first before acquiring lru_lock. */ static struct htab_elem *prealloc_lru_pop(struct bpf_htab *htab, void *key, u32 hash) { struct bpf_lru_node *node = bpf_lru_pop_free(&htab->lru, hash); struct htab_elem *l; if (node) { l = container_of(node, struct htab_elem, lru_node); memcpy(l->key, key, htab->map.key_size); return l; } return NULL; } static int prealloc_init(struct bpf_htab *htab) { u32 num_entries = htab->map.max_entries; int err = -ENOMEM, i; if (!htab_is_percpu(htab) && !htab_is_lru(htab)) num_entries += num_possible_cpus(); htab->elems = bpf_map_area_alloc(htab->elem_size * num_entries, htab->map.numa_node); if (!htab->elems) return -ENOMEM; if (!htab_is_percpu(htab)) goto skip_percpu_elems; for (i = 0; i < num_entries; i++) { u32 size = round_up(htab->map.value_size, 8); void __percpu *pptr; pptr = __alloc_percpu_gfp(size, 8, GFP_USER | __GFP_NOWARN); if (!pptr) goto free_elems; htab_elem_set_ptr(get_htab_elem(htab, i), htab->map.key_size, pptr); cond_resched(); } skip_percpu_elems: if (htab_is_lru(htab)) err = bpf_lru_init(&htab->lru, htab->map.map_flags & BPF_F_NO_COMMON_LRU, offsetof(struct htab_elem, hash) - offsetof(struct htab_elem, lru_node), htab_lru_map_delete_node, htab); else err = pcpu_freelist_init(&htab->freelist); if (err) goto free_elems; if (htab_is_lru(htab)) bpf_lru_populate(&htab->lru, htab->elems, offsetof(struct htab_elem, lru_node), htab->elem_size, num_entries); else pcpu_freelist_populate(&htab->freelist, htab->elems + offsetof(struct htab_elem, fnode), htab->elem_size, num_entries); return 0; free_elems: htab_free_elems(htab); return err; } static void prealloc_destroy(struct bpf_htab *htab) { htab_free_elems(htab); if (htab_is_lru(htab)) bpf_lru_destroy(&htab->lru); else pcpu_freelist_destroy(&htab->freelist); } static int alloc_extra_elems(struct bpf_htab *htab) { struct htab_elem *__percpu *pptr, *l_new; struct pcpu_freelist_node *l; int cpu; pptr = __alloc_percpu_gfp(sizeof(struct htab_elem *), 8, GFP_USER | __GFP_NOWARN); if (!pptr) return -ENOMEM; for_each_possible_cpu(cpu) { l = pcpu_freelist_pop(&htab->freelist); /* pop will succeed, since prealloc_init() * preallocated extra num_possible_cpus elements */ l_new = container_of(l, struct htab_elem, fnode); *per_cpu_ptr(pptr, cpu) = l_new; } htab->extra_elems = pptr; return 0; } /* Called from syscall */ static int htab_map_alloc_check(union bpf_attr *attr) { bool percpu = (attr->map_type == BPF_MAP_TYPE_PERCPU_HASH || attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH); bool lru = (attr->map_type == BPF_MAP_TYPE_LRU_HASH || attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH); /* percpu_lru means each cpu has its own LRU list. * it is different from BPF_MAP_TYPE_PERCPU_HASH where * the map's value itself is percpu. percpu_lru has * nothing to do with the map's value. */ bool percpu_lru = (attr->map_flags & BPF_F_NO_COMMON_LRU); bool prealloc = !(attr->map_flags & BPF_F_NO_PREALLOC); bool zero_seed = (attr->map_flags & BPF_F_ZERO_SEED); int numa_node = bpf_map_attr_numa_node(attr); BUILD_BUG_ON(offsetof(struct htab_elem, htab) != offsetof(struct htab_elem, hash_node.pprev)); BUILD_BUG_ON(offsetof(struct htab_elem, fnode.next) != offsetof(struct htab_elem, hash_node.pprev)); if (lru && !bpf_capable()) /* LRU implementation is much complicated than other * maps. Hence, limit to CAP_BPF. */ return -EPERM; if (zero_seed && !capable(CAP_SYS_ADMIN)) /* Guard against local DoS, and discourage production use. */ return -EPERM; if (attr->map_flags & ~HTAB_CREATE_FLAG_MASK || !bpf_map_flags_access_ok(attr->map_flags)) return -EINVAL; if (!lru && percpu_lru) return -EINVAL; if (lru && !prealloc) return -ENOTSUPP; if (numa_node != NUMA_NO_NODE && (percpu || percpu_lru)) return -EINVAL; /* check sanity of attributes. * value_size == 0 may be allowed in the future to use map as a set */ if (attr->max_entries == 0 || attr->key_size == 0 || attr->value_size == 0) return -EINVAL; if (attr->key_size > MAX_BPF_STACK) /* eBPF programs initialize keys on stack, so they cannot be * larger than max stack size */ return -E2BIG; if (attr->value_size >= KMALLOC_MAX_SIZE - MAX_BPF_STACK - sizeof(struct htab_elem)) /* if value_size is bigger, the user space won't be able to * access the elements via bpf syscall. This check also makes * sure that the elem_size doesn't overflow and it's * kmalloc-able later in htab_map_update_elem() */ return -E2BIG; return 0; } static struct bpf_map *htab_map_alloc(union bpf_attr *attr) { bool percpu = (attr->map_type == BPF_MAP_TYPE_PERCPU_HASH || attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH); bool lru = (attr->map_type == BPF_MAP_TYPE_LRU_HASH || attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH); /* percpu_lru means each cpu has its own LRU list. * it is different from BPF_MAP_TYPE_PERCPU_HASH where * the map's value itself is percpu. percpu_lru has * nothing to do with the map's value. */ bool percpu_lru = (attr->map_flags & BPF_F_NO_COMMON_LRU); bool prealloc = !(attr->map_flags & BPF_F_NO_PREALLOC); struct bpf_htab *htab; u64 cost; int err; htab = kzalloc(sizeof(*htab), GFP_USER); if (!htab) return ERR_PTR(-ENOMEM); bpf_map_init_from_attr(&htab->map, attr); if (percpu_lru) { /* ensure each CPU's lru list has >=1 elements. * since we are at it, make each lru list has the same * number of elements. */ htab->map.max_entries = roundup(attr->max_entries, num_possible_cpus()); if (htab->map.max_entries < attr->max_entries) htab->map.max_entries = rounddown(attr->max_entries, num_possible_cpus()); } /* hash table size must be power of 2 */ htab->n_buckets = roundup_pow_of_two(htab->map.max_entries); htab->elem_size = sizeof(struct htab_elem) + round_up(htab->map.key_size, 8); if (percpu) htab->elem_size += sizeof(void *); else htab->elem_size += round_up(htab->map.value_size, 8); err = -E2BIG; /* prevent zero size kmalloc and check for u32 overflow */ if (htab->n_buckets == 0 || htab->n_buckets > U32_MAX / sizeof(struct bucket)) goto free_htab; cost = (u64) htab->n_buckets * sizeof(struct bucket) + (u64) htab->elem_size * htab->map.max_entries; if (percpu) cost += (u64) round_up(htab->map.value_size, 8) * num_possible_cpus() * htab->map.max_entries; else cost += (u64) htab->elem_size * num_possible_cpus(); /* if map size is larger than memlock limit, reject it */ err = bpf_map_charge_init(&htab->map.memory, cost); if (err) goto free_htab; err = -ENOMEM; htab->buckets = bpf_map_area_alloc(htab->n_buckets * sizeof(struct bucket), htab->map.numa_node); if (!htab->buckets) goto free_charge; if (htab->map.map_flags & BPF_F_ZERO_SEED) htab->hashrnd = 0; else htab->hashrnd = get_random_int(); htab_init_buckets(htab); if (prealloc) { err = prealloc_init(htab); if (err) goto free_buckets; if (!percpu && !lru) { /* lru itself can remove the least used element, so * there is no need for an extra elem during map_update. */ err = alloc_extra_elems(htab); if (err) goto free_prealloc;