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 cant_migrate(); 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 } 26 27 static bool bpf_cgrp_storage_trylock(void) 28 { 29 cant_migrate(); 30 if (unlikely(this_cpu_inc_return(bpf_cgrp_storage_busy) != 1)) { 31 this_cpu_dec(bpf_cgrp_storage_busy); 32 return false; 33 } 34 return true; 35 } 36 37 static struct bpf_local_storage __rcu **cgroup_storage_ptr(void *owner) 38 { 39 struct cgroup *cg = owner; 40 41 return &cg->bpf_cgrp_storage; 42 } 43 44 void bpf_cgrp_storage_free(struct cgroup *cgroup) 45 { 46 struct bpf_local_storage *local_storage; 47 48 migrate_disable(); 49 rcu_read_lock(); 50 local_storage = rcu_dereference(cgroup->bpf_cgrp_storage); 51 if (!local_storage) 52 goto out; 53 54 bpf_cgrp_storage_lock(); 55 bpf_local_storage_destroy(local_storage); 56 bpf_cgrp_storage_unlock(); 57 out: 58 rcu_read_unlock(); 59 migrate_enable(); 60 } 61 62 static struct bpf_local_storage_data * 63 cgroup_storage_lookup(struct cgroup *cgroup, struct bpf_map *map, bool cacheit_lockit) 64 { 65 struct bpf_local_storage *cgroup_storage; 66 struct bpf_local_storage_map *smap; 67 68 cgroup_storage = rcu_dereference_check(cgroup->bpf_cgrp_storage, 69 bpf_rcu_lock_held()); 70 if (!cgroup_storage) 71 return NULL; 72 73 smap = (struct bpf_local_storage_map *)map; 74 return bpf_local_storage_lookup(cgroup_storage, smap, cacheit_lockit); 75 } 76 77 static void *bpf_cgrp_storage_lookup_elem(struct bpf_map *map, void *key) 78 { 79 struct bpf_local_storage_data *sdata; 80 struct cgroup *cgroup; 81 int fd; 82 83 fd = *(int *)key; 84 cgroup = cgroup_v1v2_get_from_fd(fd); 85 if (IS_ERR(cgroup)) 86 return ERR_CAST(cgroup); 87 88 bpf_cgrp_storage_lock(); 89 sdata = cgroup_storage_lookup(cgroup, map, true); 90 bpf_cgrp_storage_unlock(); 91 cgroup_put(cgroup); 92 return sdata ? sdata->data : NULL; 93 } 94 95 static long bpf_cgrp_storage_update_elem(struct bpf_map *map, void *key, 96 void *value, u64 map_flags) 97 { 98 struct bpf_local_storage_data *sdata; 99 struct cgroup *cgroup; 100 int fd; 101 102 fd = *(int *)key; 103 cgroup = cgroup_v1v2_get_from_fd(fd); 104 if (IS_ERR(cgroup)) 105 return PTR_ERR(cgroup); 106 107 bpf_cgrp_storage_lock(); 108 sdata = bpf_local_storage_update(cgroup, (struct bpf_local_storage_map *)map, 109 value, map_flags, false, GFP_ATOMIC); 110 bpf_cgrp_storage_unlock(); 111 cgroup_put(cgroup); 112 return PTR_ERR_OR_ZERO(sdata); 113 } 114 115 static int cgroup_storage_delete(struct cgroup *cgroup, struct bpf_map *map) 116 { 117 struct bpf_local_storage_data *sdata; 118 119 sdata = cgroup_storage_lookup(cgroup, map, false); 120 if (!sdata) 121 return -ENOENT; 122 123 bpf_selem_unlink(SELEM(sdata), false); 124 return 0; 125 } 126 127 static long bpf_cgrp_storage_delete_elem(struct bpf_map *map, void *key) 128 { 129 struct cgroup *cgroup; 130 int err, fd; 131 132 fd = *(int *)key; 133 cgroup = cgroup_v1v2_get_from_fd(fd); 134 if (IS_ERR(cgroup)) 135 return PTR_ERR(cgroup); 136 137 bpf_cgrp_storage_lock(); 138 err = cgroup_storage_delete(cgroup, map); 139 bpf_cgrp_storage_unlock(); 140 cgroup_put(cgroup); 141 return err; 142 } 143 144 static int notsupp_get_next_key(struct bpf_map *map, void *key, void *next_key) 145 { 146 return -ENOTSUPP; 147 } 148 149 static struct bpf_map *cgroup_storage_map_alloc(union bpf_attr *attr) 150 { 151 return bpf_local_storage_map_alloc(attr, &cgroup_cache, true); 152 } 153 154 static void cgroup_storage_map_free(struct bpf_map *map) 155 { 156 bpf_local_storage_map_free(map, &cgroup_cache, NULL); 157 } 158 159 /* *gfp_flags* is a hidden argument provided by the verifier */ 160 BPF_CALL_5(bpf_cgrp_storage_get, struct bpf_map *, map, struct cgroup *, cgroup, 161 void *, value, u64, flags, gfp_t, gfp_flags) 162 { 163 struct bpf_local_storage_data *sdata; 164 165 WARN_ON_ONCE(!bpf_rcu_lock_held()); 166 if (flags & ~(BPF_LOCAL_STORAGE_GET_F_CREATE)) 167 return (unsigned long)NULL; 168 169 if (!cgroup) 170 return (unsigned long)NULL; 171 172 if (!bpf_cgrp_storage_trylock()) 173 return (unsigned long)NULL; 174 175 sdata = cgroup_storage_lookup(cgroup, map, true); 176 if (sdata) 177 goto unlock; 178 179 /* only allocate new storage, when the cgroup is refcounted */ 180 if (!percpu_ref_is_dying(&cgroup->self.refcnt) && 181 (flags & BPF_LOCAL_STORAGE_GET_F_CREATE)) 182 sdata = bpf_local_storage_update(cgroup, (struct bpf_local_storage_map *)map, 183 value, BPF_NOEXIST, false, gfp_flags); 184 185 unlock: 186 bpf_cgrp_storage_unlock(); 187 return IS_ERR_OR_NULL(sdata) ? (unsigned long)NULL : (unsigned long)sdata->data; 188 } 189 190 BPF_CALL_2(bpf_cgrp_storage_delete, struct bpf_map *, map, struct cgroup *, cgroup) 191 { 192 int ret; 193 194 WARN_ON_ONCE(!bpf_rcu_lock_held()); 195 if (!cgroup) 196 return -EINVAL; 197 198 if (!bpf_cgrp_storage_trylock()) 199 return -EBUSY; 200 201 ret = cgroup_storage_delete(cgroup, map); 202 bpf_cgrp_storage_unlock(); 203 return ret; 204 } 205 206 const struct bpf_map_ops cgrp_storage_map_ops = { 207 .map_meta_equal = bpf_map_meta_equal, 208 .map_alloc_check = bpf_local_storage_map_alloc_check, 209 .map_alloc = cgroup_storage_map_alloc, 210 .map_free = cgroup_storage_map_free, 211 .map_get_next_key = notsupp_get_next_key, 212 .map_lookup_elem = bpf_cgrp_storage_lookup_elem, 213 .map_update_elem = bpf_cgrp_storage_update_elem, 214 .map_delete_elem = bpf_cgrp_storage_delete_elem, 215 .map_check_btf = bpf_local_storage_map_check_btf, 216 .map_mem_usage = bpf_local_storage_map_mem_usage, 217 .map_btf_id = &bpf_local_storage_map_btf_id[0], 218 .map_owner_storage_ptr = cgroup_storage_ptr, 219 }; 220 221 const struct bpf_func_proto bpf_cgrp_storage_get_proto = { 222 .func = bpf_cgrp_storage_get, 223 .gpl_only = false, 224 .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL, 225 .arg1_type = ARG_CONST_MAP_PTR, 226 .arg2_type = ARG_PTR_TO_BTF_ID_OR_NULL, 227 .arg2_btf_id = &bpf_cgroup_btf_id[0], 228 .arg3_type = ARG_PTR_TO_MAP_VALUE_OR_NULL, 229 .arg4_type = ARG_ANYTHING, 230 }; 231 232 const struct bpf_func_proto bpf_cgrp_storage_delete_proto = { 233 .func = bpf_cgrp_storage_delete, 234 .gpl_only = false, 235 .ret_type = RET_INTEGER, 236 .arg1_type = ARG_CONST_MAP_PTR, 237 .arg2_type = ARG_PTR_TO_BTF_ID_OR_NULL, 238 .arg2_btf_id = &bpf_cgroup_btf_id[0], 239 }; 240