1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (c) 2022 Meta Platforms, Inc. and affiliates. 4 */ 5 6 #include <linux/types.h> 7 #include <linux/bpf.h> 8 #include <linux/bpf_local_storage.h> 9 #include <uapi/linux/btf.h> 10 #include <linux/btf_ids.h> 11 12 DEFINE_BPF_STORAGE_CACHE(cgroup_cache); 13 14 static DEFINE_PER_CPU(int, bpf_cgrp_storage_busy); 15 16 static void bpf_cgrp_storage_lock(void) 17 { 18 migrate_disable(); 19 this_cpu_inc(bpf_cgrp_storage_busy); 20 } 21 22 static void bpf_cgrp_storage_unlock(void) 23 { 24 this_cpu_dec(bpf_cgrp_storage_busy); 25 migrate_enable(); 26 } 27 28 static bool bpf_cgrp_storage_trylock(void) 29 { 30 migrate_disable(); 31 if (unlikely(this_cpu_inc_return(bpf_cgrp_storage_busy) != 1)) { 32 this_cpu_dec(bpf_cgrp_storage_busy); 33 migrate_enable(); 34 return false; 35 } 36 return true; 37 } 38 39 static struct bpf_local_storage __rcu **cgroup_storage_ptr(void *owner) 40 { 41 struct cgroup *cg = owner; 42 43 return &cg->bpf_cgrp_storage; 44 } 45 46 void bpf_cgrp_storage_free(struct cgroup *cgroup) 47 { 48 struct bpf_local_storage *local_storage; 49 50 rcu_read_lock(); 51 local_storage = rcu_dereference(cgroup->bpf_cgrp_storage); 52 if (!local_storage) { 53 rcu_read_unlock(); 54 return; 55 } 56 57 bpf_cgrp_storage_lock(); 58 bpf_local_storage_destroy(local_storage); 59 bpf_cgrp_storage_unlock(); 60 rcu_read_unlock(); 61 } 62 63 static struct bpf_local_storage_data * 64 cgroup_storage_lookup(struct cgroup *cgroup, struct bpf_map *map, bool cacheit_lockit) 65 { 66 struct bpf_local_storage *cgroup_storage; 67 struct bpf_local_storage_map *smap; 68 69 cgroup_storage = rcu_dereference_check(cgroup->bpf_cgrp_storage, 70 bpf_rcu_lock_held()); 71 if (!cgroup_storage) 72 return NULL; 73 74 smap = (struct bpf_local_storage_map *)map; 75 return bpf_local_storage_lookup(cgroup_storage, smap, cacheit_lockit); 76 } 77 78 static void *bpf_cgrp_storage_lookup_elem(struct bpf_map *map, void *key) 79 { 80 struct bpf_local_storage_data *sdata; 81 struct cgroup *cgroup; 82 int fd; 83 84 fd = *(int *)key; 85 cgroup = cgroup_get_from_fd(fd); 86 if (IS_ERR(cgroup)) 87 return ERR_CAST(cgroup); 88 89 bpf_cgrp_storage_lock(); 90 sdata = cgroup_storage_lookup(cgroup, map, true); 91 bpf_cgrp_storage_unlock(); 92 cgroup_put(cgroup); 93 return sdata ? sdata->data : NULL; 94 } 95 96 static long bpf_cgrp_storage_update_elem(struct bpf_map *map, void *key, 97 void *value, u64 map_flags) 98 { 99 struct bpf_local_storage_data *sdata; 100 struct cgroup *cgroup; 101 int fd; 102 103 fd = *(int *)key; 104 cgroup = cgroup_get_from_fd(fd); 105 if (IS_ERR(cgroup)) 106 return PTR_ERR(cgroup); 107 108 bpf_cgrp_storage_lock(); 109 sdata = bpf_local_storage_update(cgroup, (struct bpf_local_storage_map *)map, 110 value, map_flags, GFP_ATOMIC); 111 bpf_cgrp_storage_unlock(); 112 cgroup_put(cgroup); 113 return PTR_ERR_OR_ZERO(sdata); 114 } 115 116 static int cgroup_storage_delete(struct cgroup *cgroup, struct bpf_map *map) 117 { 118 struct bpf_local_storage_data *sdata; 119 120 sdata = cgroup_storage_lookup(cgroup, map, false); 121 if (!sdata) 122 return -ENOENT; 123 124 bpf_selem_unlink(SELEM(sdata), false); 125 return 0; 126 } 127 128 static long bpf_cgrp_storage_delete_elem(struct bpf_map *map, void *key) 129 { 130 struct cgroup *cgroup; 131 int err, fd; 132 133 fd = *(int *)key; 134 cgroup = cgroup_get_from_fd(fd); 135 if (IS_ERR(cgroup)) 136 return PTR_ERR(cgroup); 137 138 bpf_cgrp_storage_lock(); 139 err = cgroup_storage_delete(cgroup, map); 140 bpf_cgrp_storage_unlock(); 141 cgroup_put(cgroup); 142 return err; 143 } 144 145 static int notsupp_get_next_key(struct bpf_map *map, void *key, void *next_key) 146 { 147 return -ENOTSUPP; 148 } 149 150 static struct bpf_map *cgroup_storage_map_alloc(union bpf_attr *attr) 151 { 152 return bpf_local_storage_map_alloc(attr, &cgroup_cache, true); 153 } 154 155 static void cgroup_storage_map_free(struct bpf_map *map) 156 { 157 bpf_local_storage_map_free(map, &cgroup_cache, NULL); 158 } 159 160 /* *gfp_flags* is a hidden argument provided by the verifier */ 161 BPF_CALL_5(bpf_cgrp_storage_get, struct bpf_map *, map, struct cgroup *, cgroup, 162 void *, value, u64, flags, gfp_t, gfp_flags) 163 { 164 struct bpf_local_storage_data *sdata; 165 166 WARN_ON_ONCE(!bpf_rcu_lock_held()); 167 if (flags & ~(BPF_LOCAL_STORAGE_GET_F_CREATE)) 168 return (unsigned long)NULL; 169 170 if (!cgroup) 171 return (unsigned long)NULL; 172 173 if (!bpf_cgrp_storage_trylock()) 174 return (unsigned long)NULL; 175 176 sdata = cgroup_storage_lookup(cgroup, map, true); 177 if (sdata) 178 goto unlock; 179 180 /* only allocate new storage, when the cgroup is refcounted */ 181 if (!percpu_ref_is_dying(&cgroup->self.refcnt) && 182 (flags & BPF_LOCAL_STORAGE_GET_F_CREATE)) 183 sdata = bpf_local_storage_update(cgroup, (struct bpf_local_storage_map *)map, 184 value, BPF_NOEXIST, gfp_flags); 185 186 unlock: 187 bpf_cgrp_storage_unlock(); 188 return IS_ERR_OR_NULL(sdata) ? (unsigned long)NULL : (unsigned long)sdata->data; 189 } 190 191 BPF_CALL_2(bpf_cgrp_storage_delete, struct bpf_map *, map, struct cgroup *, cgroup) 192 { 193 int ret; 194 195 WARN_ON_ONCE(!bpf_rcu_lock_held()); 196 if (!cgroup) 197 return -EINVAL; 198 199 if (!bpf_cgrp_storage_trylock()) 200 return -EBUSY; 201 202 ret = cgroup_storage_delete(cgroup, map); 203 bpf_cgrp_storage_unlock(); 204 return ret; 205 } 206 207 const struct bpf_map_ops cgrp_storage_map_ops = { 208 .map_meta_equal = bpf_map_meta_equal, 209 .map_alloc_check = bpf_local_storage_map_alloc_check, 210 .map_alloc = cgroup_storage_map_alloc, 211 .map_free = cgroup_storage_map_free, 212 .map_get_next_key = notsupp_get_next_key, 213 .map_lookup_elem = bpf_cgrp_storage_lookup_elem, 214 .map_update_elem = bpf_cgrp_storage_update_elem, 215 .map_delete_elem = bpf_cgrp_storage_delete_elem, 216 .map_check_btf = bpf_local_storage_map_check_btf, 217 .map_mem_usage = bpf_local_storage_map_mem_usage, 218 .map_btf_id = &bpf_local_storage_map_btf_id[0], 219 .map_owner_storage_ptr = cgroup_storage_ptr, 220 }; 221 222 const struct bpf_func_proto bpf_cgrp_storage_get_proto = { 223 .func = bpf_cgrp_storage_get, 224 .gpl_only = false, 225 .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL, 226 .arg1_type = ARG_CONST_MAP_PTR, 227 .arg2_type = ARG_PTR_TO_BTF_ID_OR_NULL, 228 .arg2_btf_id = &bpf_cgroup_btf_id[0], 229 .arg3_type = ARG_PTR_TO_MAP_VALUE_OR_NULL, 230 .arg4_type = ARG_ANYTHING, 231 }; 232 233 const struct bpf_func_proto bpf_cgrp_storage_delete_proto = { 234 .func = bpf_cgrp_storage_delete, 235 .gpl_only = false, 236 .ret_type = RET_INTEGER, 237 .arg1_type = ARG_CONST_MAP_PTR, 238 .arg2_type = ARG_PTR_TO_BTF_ID_OR_NULL, 239 .arg2_btf_id = &bpf_cgroup_btf_id[0], 240 }; 241