/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com * Copyright (c) 2016,2017 Facebook * * This program is free software; you can redistribute it and/or * modify it under the terms of version 2 of the GNU General Public * License as published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. */ #include #include #include #include #include #include #include #include #include "map_in_map.h" #define ARRAY_CREATE_FLAG_MASK \ (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY) static void bpf_array_free_percpu(struct bpf_array *array) { int i; for (i = 0; i < array->map.max_entries; i++) { free_percpu(array->pptrs[i]); cond_resched(); } } static int bpf_array_alloc_percpu(struct bpf_array *array) { void __percpu *ptr; int i; for (i = 0; i < array->map.max_entries; i++) { ptr = __alloc_percpu_gfp(array->elem_size, 8, GFP_USER | __GFP_NOWARN); if (!ptr) { bpf_array_free_percpu(array); return -ENOMEM; } array->pptrs[i] = ptr; cond_resched(); } return 0; } /* Called from syscall */ static int array_map_alloc_check(union bpf_attr *attr) { bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY; int numa_node = bpf_map_attr_numa_node(attr); /* check sanity of attributes */ if (attr->max_entries == 0 || attr->key_size != 4 || attr->value_size == 0 || attr->map_flags & ~ARRAY_CREATE_FLAG_MASK || (percpu && numa_node != NUMA_NO_NODE)) return -EINVAL; if (attr->value_size > KMALLOC_MAX_SIZE) /* if value_size is bigger, the user space won't be able to * access the elements. */ return -E2BIG; return 0; } static struct bpf_map *array_map_alloc(union bpf_attr *attr) { bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY; int ret, numa_node = bpf_map_attr_numa_node(attr); u32 elem_size, index_mask, max_entries; bool unpriv = !capable(CAP_SYS_ADMIN); u64 cost, array_size, mask64; struct bpf_array *array; elem_size = round_up(attr->value_size, 8); max_entries = attr->max_entries; /* On 32 bit archs roundup_pow_of_two() with max_entries that has * upper most bit set in u32 space is undefined behavior due to * resulting 1U << 32, so do it manually here in u64 space. */ mask64 = fls_long(max_entries - 1); mask64 = 1ULL << mask64; mask64 -= 1; index_mask = mask64; if (unpriv) { /* round up array size to nearest power of 2, * since cpu will speculate within index_mask limits */ max_entries = index_mask + 1; /* Check for overflows. */ if (max_entries < attr->max_entries) return ERR_PTR(-E2BIG); } array_size = sizeof(*array); if (percpu) array_size += (u64) max_entries * sizeof(void *); else array_size += (u64) max_entries * elem_size; /* make sure there is no u32 overflow later in round_up() */ cost = array_size; if (cost >= U32_MAX - PAGE_SIZE) return ERR_PTR(-ENOMEM); if (percpu) { cost += (u64)attr->max_entries * elem_size * num_possible_cpus(); if (cost >= U32_MAX - PAGE_SIZE) return ERR_PTR(-ENOMEM); } cost = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT; ret = bpf_map_precharge_memlock(cost); if (ret < 0) return ERR_PTR(ret); /* allocate all map elements and zero-initialize them */ array = bpf_map_area_alloc(array_size, numa_node); if (!array) return ERR_PTR(-ENOMEM); array->index_mask = index_mask; array->map.unpriv_array = unpriv; /* copy mandatory map attributes */ bpf_map_init_from_attr(&array->map, attr); array->map.pages = cost; array->elem_size = elem_size; if (percpu && bpf_array_alloc_percpu(array)) { bpf_map_area_free(array); return ERR_PTR(-ENOMEM); } return &array->map; } /* Called from syscall or from eBPF program */ static void *array_map_lookup_elem(struct bpf_map *map, void *key) { struct bpf_array *array = container_of(map, struct bpf_array, map); u32 index = *(u32 *)key; if (unlikely(index >= array->map.max_entries)) return NULL; return array->value + array->elem_size * (index & array->index_mask); } /* emit BPF instructions equivalent to C code of array_map_lookup_elem() */ static u32 array_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf) { struct bpf_array *array = container_of(map, struct bpf_array, map); struct bpf_insn *insn = insn_buf; u32 elem_size = round_up(map->value_size, 8); const int ret = BPF_REG_0; const int map_ptr = BPF_REG_1; const int index = BPF_REG_2; *insn++ = BPF_ALU64_IMM(BPF_ADD, map_ptr, offsetof(struct bpf_array, value)); *insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0); if (map->unpriv_array) { *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 4); *insn++ = BPF_ALU32_IMM(BPF_AND, ret, array->index_mask); } else { *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 3); } if (is_power_of_2(elem_size)) { *insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(elem_size)); } else { *insn++ = BPF_ALU64_IMM(BPF_MUL, ret, elem_size); } *insn++ = BPF_ALU64_REG(BPF_ADD, ret, map_ptr); *insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1); *insn++ = BPF_MOV64_IMM(ret, 0); return insn - insn_buf; } /* Called from eBPF program */ static void *percpu_array_map_lookup_elem(struct bpf_map *map, void *key) { struct bpf_array *array = container_of(map, struct bpf_array, map); u32 index = *(u32 *)key; if (unlikely(index >= array->map.max_entries)) return NULL; return this_cpu_ptr(array->pptrs[index & array->index_mask]); } int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value) { struct bpf_array *array = container_of(map, struct bpf_array, map); u32 index = *(u32 *)key; void __percpu *pptr; int cpu, off = 0; u32 size; if (unlikely(index >= array->map.max_entries)) return -ENOENT; /* per_cpu areas are zero-filled and bpf programs can only * access 'value_size' of them, so copying rounded areas * will not leak any kernel data */ size = round_up(map->value_size, 8); rcu_read_lock(); pptr = array->pptrs[index & array->index_mask]; for_each_possible_cpu(cpu) { bpf_long_memcpy(value + off, per_cpu_ptr(pptr, cpu), size); off += size; } rcu_read_unlock(); return 0; } /* Called from syscall */ static int array_map_get_next_key(struct bpf_map *map, void *key, void *next_key) { struct bpf_array *array = container_of(map, struct bpf_array, map); u32 index = key ? *(u32 *)key : U32_MAX; u32 *next = (u32 *)next_key; if (index >= array->map.max_entries) { *next = 0; return 0; } if (index == array->map.max_entries - 1) return -ENOENT; *next = index + 1; return 0; } /* Called from syscall or from eBPF program */ static int array_map_update_elem(struct bpf_map *map, void *key, void *value, u64 map_flags) { struct bpf_array *array = container_of(map, struct bpf_array, map); u32 index = *(u32 *)key; if (unlikely(map_flags > BPF_EXIST)) /* unknown flags */ return -EINVAL; if (unlikely(index >= array->map.max_entries)) /* all elements were pre-allocated, cannot insert a new one */ return -E2BIG; if (unlikely(map_flags == BPF_NOEXIST)) /* all elements already exist */ return -EEXIST; if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY) memcpy(this_cpu_ptr(array->pptrs[index & array->index_mask]), value, map->value_size); else memcpy(array->value + array->elem_size * (index & array->index_mask), value, map->value_size); return 0; } int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value, u64 map_flags) { struct bpf_array *array = container_of(map, struct bpf_array, map); u32 index = *(u32 *)key; void __percpu *pptr; int cpu, off = 0; u32 size; if (unlikely(map_flags > BPF_EXIST)) /* unknown flags */ return -EINVAL; if (unlikely(index >= array->map.max_entries)) /* all elements were pre-allocated, cannot insert a new one */ return -E2BIG; if (unlikely(map_flags == BPF_NOEXIST)) /* all elements already exist */ return -EEXIST; /* the user space will provide round_up(value_size, 8) bytes that * will be copied into per-cpu area. bpf programs can only access * value_size of it. During lookup the same extra bytes will be * returned or zeros which were zero-filled by percpu_alloc, * so no kernel data leaks possible */ size = round_up(map->value_size, 8); rcu_read_lock(); pptr = array->pptrs[index & array->index_mask]; for_each_possible_cpu(cpu) { bpf_long_memcpy(per_cpu_ptr(pptr, cpu), value + off, size); off += size; } rcu_read_unlock(); return 0; } /* Called from syscall or from eBPF program */ static int array_map_delete_elem(struct bpf_map *map, void *key) { return -EINVAL; } /* Called when map->refcnt goes to zero, either from workqueue or from syscall */ static void array_map_free(struct bpf_map *map) { struct bpf_array *array = container_of(map, struct bpf_array, map); /* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0, * so the programs (can be more than one that used this map) were * disconnected from events. Wait for outstanding programs to complete * and free the array */ synchronize_rcu(); if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY) bpf_array_free_percpu(array); bpf_map_area_free(array); } static void array_map_seq_show_elem(struct bpf_map *map, void *key, struct seq_file *m) { void *value; rcu_read_lock(); value = array_map_lookup_elem(map, key); if (!value) { rcu_read_unlock(); return; } seq_printf(m, "%u: ", *(u32 *)key); btf_type_seq_show(map->btf, map->btf_value_id, value, m); seq_puts(m, "\n"); rcu_read_unlock(); } static int array_map_check_btf(const struct bpf_map *map, const struct btf *btf, u32 btf_key_id, u32 btf_value_id) { const struct btf_type *key_type, *value_type; u32 key_size, value_size; u32 int_data; key_type = btf_type_id_size(btf, &btf_key_id, &key_size); if (!key_type || BTF_INFO_KIND(key_type->info) != BTF_KIND_INT) return -EINVAL; int_data = *(u32 *)(key_type + 1); /* bpf array can only take a u32 key. This check makes * sure that the btf matches the attr used during map_create. */ if (BTF_INT_BITS(int_data) != 32 || key_size != 4 || BTF_INT_OFFSET(int_data)) return -EINVAL; value_type = btf_type_id_size(btf, &btf_value_id, &value_size); if (!value_type || value_size > map->value_size) return -EINVAL; return 0; } const struct bpf_map_ops array_map_ops = { .map_alloc_check = array_map_alloc_check, .map_alloc = array_map_alloc, .map_free = array_map_free, .map_get_next_key = array_map_get_next_key, .map_lookup_elem = array_map_lookup_elem, .map_update_elem = array_map_update_elem, .map_delete_elem = array_map_delete_elem, .map_gen_lookup = array_map_gen_lookup, .map_seq_show_elem = array_map_seq_show_elem, .map_check_btf = array_map_check_btf, }; const struct bpf_map_ops percpu_array_map_ops = { .map_alloc_check = array_map_alloc_check, .map_alloc = array_map_alloc, .map_free = array_map_free, .map_get_next_key = array_map_get_next_key, .map_lookup_elem = percpu_array_map_lookup_elem, .map_update_elem = array_map_update_elem, .map_delete_elem = array_map_delete_elem, }; static int fd_array_map_alloc_check(union bpf_attr *attr) { /* only file descriptors can be stored in this type of map */ if (attr->value_size != sizeof(u32)) return -EINVAL; return array_map_alloc_check(attr); } static void fd_array_map_free(struct bpf_map *map) { struct bpf_array *array = container_of(map, struct bpf_array, map); int i; synchronize_rcu(); /* make sure it's empty */ for (i = 0; i < array->map.max_entries; i++) BUG_ON(array->ptrs[i] != NULL); bpf_map_area_free(array); } static void *fd_array_map_lookup_elem(struct bpf_map *map, void *key) { return NULL; } /* only called from syscall */ int bpf_fd_array_map_lookup_elem(struct bpf_map *map, void *key, u32 *value) { void **elem, *ptr; int ret = 0; if (!map->ops->map_fd_sys_lookup_elem) return -ENOTSUPP; rcu_read_lock(); elem = array_map_lookup_elem(map, key); if (elem && (ptr = READ_ONCE(*elem))) *value = map->ops->map_fd_sys_lookup_elem(ptr); else ret = -ENOENT; rcu_read_unlock(); return ret; } /* only called from syscall */ int bpf_fd_array_map_update_elem(struct bpf_map *map, struct file *map_file, void *key, void *value, u64 map_flags) { struct bpf_array *array = container_of(map, struct bpf_array, map); void *new_ptr, *old_ptr; u32 index = *(u32 *)key, ufd; if (map_flags != BPF_ANY) return -EINVAL; if (index >= array->map.max_entries) return -E2BIG; ufd = *(u32 *)value; new_ptr = map->ops->map_fd_get_ptr(map, map_file, ufd); if (IS_ERR(new_ptr)) return PTR_ERR(new_ptr); old_ptr = xchg(array->ptrs + index, new_ptr); if (old_ptr) map->ops->map_fd_put_ptr(old_ptr); return 0; } static int fd_array_map_delete_elem(struct bpf_map *map, void *key) { struct bpf_array *array = container_of(map, struct bpf_array, map); void *old_ptr; u32 index = *(u32 *)key; if (index >= array->map.max_entries) return -E2BIG; old_ptr = xchg(array->ptrs + index, NULL); if (old_ptr) { map->ops->map_fd_put_ptr(old_ptr); return 0; } else { return -ENOENT; } } static void *prog_fd_array_get_ptr(struct bpf_map *map, struct file *map_file, int fd) { struct bpf_array *array = container_of(map, struct bpf_array, map); struct bpf_prog *prog = bpf_prog_get(fd); if (IS_ERR(prog)) return prog; if (!bpf_prog_array_compatible(array, prog)) { bpf_prog_put(prog); return ERR_PTR(-EINVAL); } return prog; } static void prog_fd_array_put_ptr(void *ptr) { bpf_prog_put(ptr); } static u32 prog_fd_array_sys_lookup_elem(void *ptr) { return ((struct bpf_prog *)ptr)->aux->id; } /* decrement refcnt of all bpf_progs that are stored in this map */ void bpf_fd_array_map_clear(struct bpf_map *map) { struct bpf_array *array = container_of(map, struct bpf_array, map); int i; for (i = 0; i < array->map.max_entries; i++) fd_array_map_delete_elem(map, &i); } const struct bpf_map_ops prog_array_map_ops = { .map_alloc_check = fd_array_map_alloc_check, .map_alloc = array_map_alloc, .map_free = fd_array_map_free, .map_get_next_key = array_map_get_next_key, .map_lookup_elem = fd_array_map_lookup_elem, .map_delete_elem = fd_array_map_delete_elem, .map_fd_get_ptr = prog_fd_array_get_ptr, .map_fd_put_ptr = prog_fd_array_put_ptr, .map_fd_sys_lookup_elem = prog_fd_array_sys_lookup_elem, }; static struct bpf_event_entry *bpf_event_entry_gen(struct file *perf_file, struct file *map_file) { struct bpf_event_entry *ee; ee = kzalloc(sizeof(*ee), GFP_ATOMIC); if (ee) { ee->event = perf_file->private_data; ee->perf_file = perf_file; ee->map_file = map_file; } return ee; } static void __bpf_event_entry_free(struct rcu_head *rcu) { struct bpf_event_entry *ee; ee = container_of(rcu, struct bpf_event_entry, rcu); fput(ee->perf_file); kfree(ee); } static void bpf_event_entry_free_rcu(struct bpf_event_entry *ee) { call_rcu(&ee->rcu, __bpf_event_entry_free); } static void *perf_event_fd_array_get_ptr(struct bpf_map *map, struct file *map_file, int fd) { struct bpf_event_entry *ee; struct perf_event *event; struct file *perf_file; u64 value; perf_file = perf_event_get(fd); if (IS_ERR(perf_file)) return perf_file; ee = ERR_PTR(-EOPNOTSUPP); event = perf_file->private_data; if (perf_event_read_local(event, &value, NULL, NULL) == -EOPNOTSUPP) goto err_out; ee = bpf_event_entry_gen(perf_file, map_file); if (ee) return ee; ee = ERR_PTR(-ENOMEM); err_out: fput(perf_file); return ee; } static void perf_event_fd_array_put_ptr(void *ptr) { bpf_event_entry_free_rcu(ptr); } static void perf_event_fd_array_release(struct bpf_map *map, struct file *map_file) { struct bpf_array *array = container_of(map, struct bpf_array, map); struct bpf_event_entry *ee; int i; rcu_read_lock(); for (i = 0; i < array->map.max_entries; i++) { ee = READ_ONCE(array->ptrs[i]); if (ee && ee->map_file == map_file) fd_array_map_delete_elem(map, &i); } rcu_read_unlock(); } const struct bpf_map_ops perf_event_array_map_ops = { .map_alloc_check = fd_array_map_alloc_check, .map_alloc = array_map_alloc, .map_free = fd_array_map_free, .map_get_next_key = array_map_get_next_key, .map_lookup_elem = fd_array_map_lookup_elem, .map_delete_elem = fd_array_map_delete_elem, .map_fd_get_ptr = perf_event_fd_array_get_ptr, .map_fd_put_ptr = perf_event_fd_array_put_ptr, .map_release = perf_event_fd_array_release, }; #ifdef CONFIG_CGROUPS static void *cgroup_fd_array_get_ptr(struct bpf_map *map, struct file *map_file /* not used */, int fd) { return cgroup_get_from_fd(fd); } static void cgroup_fd_array_put_ptr(void *ptr) { /* cgroup_put free cgrp after a rcu grace period */ cgroup_put(ptr); } static void cgroup_fd_array_free(struct bpf_map *map) { bpf_fd_array_map_clear(map); fd_array_map_free(map); } const struct bpf_map_ops cgroup_array_map_ops = { .map_alloc_check = fd_array_map_alloc_check, .map_alloc = array_map_alloc, .map_free = cgroup_fd_array_free, .map_get_next_key = array_map_get_next_key, .map_lookup_elem = fd_array_map_lookup_elem, .map_delete_elem = fd_array_map_delete_elem, .map_fd_get_ptr = cgroup_fd_array_get_ptr, .map_fd_put_ptr = cgroup_fd_array_put_ptr, }; #endif static struct bpf_map *array_of_map_alloc(union bpf_attr *attr) { struct bpf_map *map, *inner_map_meta; inner_map_meta = bpf_map_meta_alloc(attr->inner_map_fd); if (IS_ERR(inner_map_meta)) return inner_map_meta; map = array_map_alloc(attr); if (IS_ERR(map)) { bpf_map_meta_free(inner_map_meta); return map; } map->inner_map_meta = inner_map_meta; return map; } static void array_of_map_free(struct bpf_map *map) { /* map->inner_map_meta is only accessed by syscall which * is protected by fdget/fdput. */ bpf_map_meta_free(map->inner_map_meta); bpf_fd_array_map_clear(map); fd_array_map_free(map); } static void *array_of_map_lookup_elem(struct bpf_map *map, void *key) { struct bpf_map **inner_map = array_map_lookup_elem(map, key); if (!inner_map) return NULL; return READ_ONCE(*inner_map); } static u32 array_of_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf) { struct bpf_array *array = container_of(map, struct bpf_array, map); u32 elem_size = round_up(map->value_size, 8); struct bpf_insn *insn = insn_buf; const int ret = BPF_REG_0; const int map_ptr = BPF_REG_1; const int index = BPF_REG_2; *insn++ = BPF_ALU64_IMM(BPF_ADD, map_ptr, offsetof(struct bpf_array, value)); *insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0); if (map->unpriv_array) { *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 6); *insn++ = BPF_ALU32_IMM(BPF_AND, ret, array->index_mask); } else { *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5); } if (is_power_of_2(elem_size)) *insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(elem_size)); else *insn++ = BPF_ALU64_IMM(BPF_MUL, ret, elem_size); *insn++ = BPF_ALU64_REG(BPF_ADD, ret, map_ptr); *insn++ = BPF_LDX_MEM(BPF_DW, ret, ret, 0); *insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 1); *insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1); *insn++ = BPF_MOV64_IMM(ret, 0); return insn - insn_buf; } const struct bpf_map_ops array_of_maps_map_ops = { .map_alloc_check = fd_array_map_alloc_check, .map_alloc = array_of_map_alloc, .map_free = array_of_map_free, .map_get_next_key = array_map_get_next_key, .map_lookup_elem = array_of_map_lookup_elem, .map_delete_elem = fd_array_map_delete_elem, .map_fd_get_ptr = bpf_map_fd_get_ptr, .map_fd_put_ptr = bpf_map_fd_put_ptr, .map_fd_sys_lookup_elem = bpf_map_fd_sys_lookup_elem, .map_gen_lookup = array_of_map_gen_lookup, };