// 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/rcupdate_wait.h>#include <linux/random.h>#include <linux/rhashtable.h>#include <uapi/linux/btf.h>#include <linux/rcupdate_trace.h>#include <linux/btf_ids.h>#include "percpu_freelist.h"#include "bpf_lru_list.h"#include "map_in_map.h"#include <linux/bpf_mem_alloc.h>#include <asm/rqspinlock.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 different * 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 across 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 paths 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(GFP_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. Before the introduction of bpf_mem_alloc, * it is only safe to use raw spinlock for preallocated hash map on a RT kernel, * because there is no memory allocation within the lock held sections. However * after hash map was fully converted to use bpf_mem_alloc, there will be * non-synchronous memory allocation for non-preallocated hash map, so it is * safe to always use raw spinlock for bucket lock. */struct bucket { struct hlist_nulls_head head; rqspinlock_t raw_lock;}; struct bpf_htab { struct bpf_map map; struct bpf_mem_alloc ma; struct bpf_mem_alloc pcpu_ma; struct bucket *buckets; void *elems; union { struct pcpu_freelist freelist; struct bpf_lru lru; }; struct htab_elem *__percpu *extra_elems; /* number of elements in non-preallocated hashtable are kept * in either pcount or count */ struct percpu_counter pcount; atomic_t count; bool use_percpu_counter; 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 pcpu_freelist_node fnode; struct htab_elem *batch_flink; }; }; }; union { /* pointer to per-cpu pointer */ void *ptr_to_pptr; struct bpf_lru_node lru_node; }; u32 hash; char key[] __aligned(8);}; struct htab_btf_record { struct btf_record *record; u32 key_size;}; static inline bool htab_is_prealloc(const struct bpf_htab *htab){ return !(htab->map.map_flags & BPF_F_NO_PREALLOC);} static void htab_init_buckets(struct bpf_htab *htab){ unsigned int i; for (i = 0; i < htab->n_buckets; i++) { INIT_HLIST_NULLS_HEAD(&htab->buckets[i].head, i); raw_res_spin_lock_init(&htab->buckets[i].raw_lock); cond_resched(); }} static inline int htab_lock_bucket(struct bucket *b, unsigned long *pflags){ unsigned long flags; int ret; ret = raw_res_spin_lock_irqsave(&b->raw_lock, flags); if (ret) return ret; *pflags = flags; return 0;} static inline void htab_unlock_bucket(struct bucket *b, unsigned long flags){ raw_res_spin_unlock_irqrestore(&b->raw_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 bool is_fd_htab(const struct bpf_htab *htab){ return htab->map.map_type == BPF_MAP_TYPE_HASH_OF_MAPS;} static inline void *htab_elem_value(struct htab_elem *l, u32 key_size){ return l->key + round_up(key_size, 8);} static inline void htab_elem_set_ptr(struct htab_elem *l, u32 key_size, void __percpu *pptr){ *(void __percpu **)htab_elem_value(l, key_size) = pptr;} static inline void __percpu *htab_elem_get_ptr(struct htab_elem *l, u32 key_size){ return *(void __percpu **)htab_elem_value(l, key_size);} static void *fd_htab_map_get_ptr(const struct bpf_map *map, struct htab_elem *l){ return *(void **)htab_elem_value(l, map->key_size);} static struct htab_elem *get_htab_elem(struct bpf_htab *htab, int i){ return (struct htab_elem *) (htab->elems + i * (u64)htab->elem_size);} /* Both percpu and fd htab support in-place update, so no need for * extra elem. LRU itself can remove the least used element, so * there is no need for an extra elem during map_update. */static bool htab_has_extra_elems(struct bpf_htab *htab){ return !htab_is_percpu(htab) && !htab_is_lru(htab) && !is_fd_htab(htab);} static void htab_free_prealloced_internal_structs(struct bpf_htab *htab){ u32 num_entries = htab->map.max_entries; int i; if (htab_has_extra_elems(htab)) num_entries += num_possible_cpus(); for (i = 0; i < num_entries; i++) { struct htab_elem *elem; elem = get_htab_elem(htab, i); bpf_map_free_internal_structs(&htab->map, htab_elem_value(elem, htab->map.key_size)); cond_resched(); }} static void htab_free_prealloced_fields(struct bpf_htab *htab){ u32 num_entries = htab->map.max_entries; int i; if (IS_ERR_OR_NULL(htab->map.record)) return; /* * Preallocated maps do not have a bpf_mem_alloc destructor, so fully * destroy every element, including the extra elements. */ if (htab_has_extra_elems(htab)) num_entries += num_possible_cpus(); for (i = 0; i < num_entries; i++) { struct htab_elem *elem; elem = get_htab_elem(htab, i); if (htab_is_percpu(htab)) { void __percpu *pptr = htab_elem_get_ptr(elem, htab->map.key_size); int cpu; for_each_possible_cpu(cpu) { bpf_obj_free_fields(htab->map.record, per_cpu_ptr(pptr, cpu)); cond_resched(); } } else { bpf_obj_free_fields(htab->map.record, htab_elem_value(elem, htab->map.key_size)); cond_resched(); } cond_resched(); }} 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) { bpf_map_inc_elem_count(&htab->map); 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_has_extra_elems(htab)) num_entries += num_possible_cpus(); htab->elems = bpf_map_area_alloc((u64)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 = bpf_map_alloc_percpu(&htab->map, 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 = bpf_map_alloc_percpu(&htab->map, 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, fnode.next) != offsetof(struct htab_elem, hash_node.pprev)); 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 ((u64)attr->key_size + attr->value_size >= KMALLOC_MAX_SIZE - sizeof(struct htab_elem)) /* if key_size + 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; /* percpu map value size is bound by PCPU_MIN_UNIT_SIZE */ if (percpu && round_up(attr->value_size, 8) > PCPU_MIN_UNIT_SIZE) return -E2BIG; return 0;} static void htab_mem_dtor(void *obj, void *ctx){ struct htab_btf_record *hrec = ctx; struct htab_elem *elem = obj; void *map_value; if (IS_ERR_OR_NULL(hrec->record)) return; map_value = htab_elem_value(elem, hrec->key_size); bpf_obj_free_fields(hrec->record, map_value);} static void htab_pcpu_mem_dtor(void *obj, void *ctx){ void __percpu *pptr = *(void __percpu **)obj; struct htab_btf_record *hrec = ctx; int cpu; if (IS_ERR_OR_NULL(hrec->record)) return; for_each_possible_cpu(cpu) bpf_obj_free_fields(hrec->record, per_cpu_ptr(pptr, cpu));} static void htab_dtor_ctx_free(void *ctx){ struct htab_btf_record *hrec = ctx; btf_record_free(hrec->record);Lines 1–500 of 3528. Load more
// 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/rcupdate_wait.h> #include <linux/random.h> #include <linux/rhashtable.h> #include <uapi/linux/btf.h> #include <linux/rcupdate_trace.h> #include <linux/btf_ids.h> #include "percpu_freelist.h" #include "bpf_lru_list.h" #include "map_in_map.h" #include <linux/bpf_mem_alloc.h> #include <asm/rqspinlock.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 different * 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 across 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 paths 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(GFP_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. Before the introduction of bpf_mem_alloc, * it is only safe to use raw spinlock for preallocated hash map on a RT kernel, * because there is no memory allocation within the lock held sections. However * after hash map was fully converted to use bpf_mem_alloc, there will be * non-synchronous memory allocation for non-preallocated hash map, so it is * safe to always use raw spinlock for bucket lock. */ struct bucket { struct hlist_nulls_head head; rqspinlock_t raw_lock; }; struct bpf_htab { struct bpf_map map; struct bpf_mem_alloc ma; struct bpf_mem_alloc pcpu_ma; struct bucket *buckets; void *elems; union { struct pcpu_freelist freelist; struct bpf_lru lru; }; struct htab_elem *__percpu *extra_elems; /* number of elements in non-preallocated hashtable are kept * in either pcount or count */ struct percpu_counter pcount; atomic_t count; bool use_percpu_counter; 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 pcpu_freelist_node fnode; struct htab_elem *batch_flink; }; }; }; union { /* pointer to per-cpu pointer */ void *ptr_to_pptr; struct bpf_lru_node lru_node; }; u32 hash; char key[] __aligned(8); }; struct htab_btf_record { struct btf_record *record; u32 key_size; }; static inline bool htab_is_prealloc(const struct bpf_htab *htab) { return !(htab->map.map_flags & BPF_F_NO_PREALLOC); } static void htab_init_buckets(struct bpf_htab *htab) { unsigned int i; for (i = 0; i < htab->n_buckets; i++) { INIT_HLIST_NULLS_HEAD(&htab->buckets[i].head, i); raw_res_spin_lock_init(&htab->buckets[i].raw_lock); cond_resched(); } } static inline int htab_lock_bucket(struct bucket *b, unsigned long *pflags) { unsigned long flags; int ret; ret = raw_res_spin_lock_irqsave(&b->raw_lock, flags); if (ret) return ret; *pflags = flags; return 0; } static inline void htab_unlock_bucket(struct bucket *b, unsigned long flags) { raw_res_spin_unlock_irqrestore(&b->raw_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 bool is_fd_htab(const struct bpf_htab *htab) { return htab->map.map_type == BPF_MAP_TYPE_HASH_OF_MAPS; } static inline void *htab_elem_value(struct htab_elem *l, u32 key_size) { return l->key + round_up(key_size, 8); } static inline void htab_elem_set_ptr(struct htab_elem *l, u32 key_size, void __percpu *pptr) { *(void __percpu **)htab_elem_value(l, key_size) = pptr; } static inline void __percpu *htab_elem_get_ptr(struct htab_elem *l, u32 key_size) { return *(void __percpu **)htab_elem_value(l, key_size); } static void *fd_htab_map_get_ptr(const struct bpf_map *map, struct htab_elem *l) { return *(void **)htab_elem_value(l, map->key_size); } static struct htab_elem *get_htab_elem(struct bpf_htab *htab, int i) { return (struct htab_elem *) (htab->elems + i * (u64)htab->elem_size); } /* Both percpu and fd htab support in-place update, so no need for * extra elem. LRU itself can remove the least used element, so * there is no need for an extra elem during map_update. */ static bool htab_has_extra_elems(struct bpf_htab *htab) { return !htab_is_percpu(htab) && !htab_is_lru(htab) && !is_fd_htab(htab); } static void htab_free_prealloced_internal_structs(struct bpf_htab *htab) { u32 num_entries = htab->map.max_entries; int i; if (htab_has_extra_elems(htab)) num_entries += num_possible_cpus(); for (i = 0; i < num_entries; i++) { struct htab_elem *elem; elem = get_htab_elem(htab, i); bpf_map_free_internal_structs(&htab->map, htab_elem_value(elem, htab->map.key_size)); cond_resched(); } } static void htab_free_prealloced_fields(struct bpf_htab *htab) { u32 num_entries = htab->map.max_entries; int i; if (IS_ERR_OR_NULL(htab->map.record)) return; /* * Preallocated maps do not have a bpf_mem_alloc destructor, so fully * destroy every element, including the extra elements. */ if (htab_has_extra_elems(htab)) num_entries += num_possible_cpus(); for (i = 0; i < num_entries; i++) { struct htab_elem *elem; elem = get_htab_elem(htab, i); if (htab_is_percpu(htab)) { void __percpu *pptr = htab_elem_get_ptr(elem, htab->map.key_size); int cpu; for_each_possible_cpu(cpu) { bpf_obj_free_fields(htab->map.record, per_cpu_ptr(pptr, cpu)); cond_resched(); } } else { bpf_obj_free_fields(htab->map.record, htab_elem_value(elem, htab->map.key_size)); cond_resched(); } cond_resched(); } } 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) { bpf_map_inc_elem_count(&htab->map); 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_has_extra_elems(htab)) num_entries += num_possible_cpus(); htab->elems = bpf_map_area_alloc((u64)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 = bpf_map_alloc_percpu(&htab->map, 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 = bpf_map_alloc_percpu(&htab->map, 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, fnode.next) != offsetof(struct htab_elem, hash_node.pprev)); 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 ((u64)attr->key_size + attr->value_size >= KMALLOC_MAX_SIZE - sizeof(struct htab_elem)) /* if key_size + 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; /* percpu map value size is bound by PCPU_MIN_UNIT_SIZE */ if (percpu && round_up(attr->value_size, 8) > PCPU_MIN_UNIT_SIZE) return -E2BIG; return 0; } static void htab_mem_dtor(void *obj, void *ctx) { struct htab_btf_record *hrec = ctx; struct htab_elem *elem = obj; void *map_value; if (IS_ERR_OR_NULL(hrec->record)) return; map_value = htab_elem_value(elem, hrec->key_size); bpf_obj_free_fields(hrec->record, map_value); } static void htab_pcpu_mem_dtor(void *obj, void *ctx) { void __percpu *pptr = *(void __percpu **)obj; struct htab_btf_record *hrec = ctx; int cpu; if (IS_ERR_OR_NULL(hrec->record)) return; for_each_possible_cpu(cpu) bpf_obj_free_fields(hrec->record, per_cpu_ptr(pptr, cpu)); } static void htab_dtor_ctx_free(void *ctx) { struct htab_btf_record *hrec = ctx; btf_record_free(hrec->record);