1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (c) 2019 Facebook 4 * Copyright 2020 Google LLC. 5 */ 6 7 #include <linux/rculist.h> 8 #include <linux/list.h> 9 #include <linux/hash.h> 10 #include <linux/types.h> 11 #include <linux/spinlock.h> 12 #include <linux/bpf.h> 13 #include <linux/bpf_local_storage.h> 14 #include <net/sock.h> 15 #include <uapi/linux/sock_diag.h> 16 #include <uapi/linux/btf.h> 17 #include <linux/bpf_lsm.h> 18 #include <linux/btf_ids.h> 19 #include <linux/fdtable.h> 20 #include <linux/rcupdate_trace.h> 21 22 DEFINE_BPF_STORAGE_CACHE(inode_cache); 23 24 static struct bpf_local_storage __rcu ** 25 inode_storage_ptr(void *owner) 26 { 27 struct inode *inode = owner; 28 struct bpf_storage_blob *bsb; 29 30 bsb = bpf_inode(inode); 31 if (!bsb) 32 return NULL; 33 return &bsb->storage; 34 } 35 36 static struct bpf_local_storage_data *inode_storage_lookup(struct inode *inode, 37 struct bpf_map *map, 38 bool cacheit_lockit) 39 { 40 struct bpf_local_storage *inode_storage; 41 struct bpf_local_storage_map *smap; 42 struct bpf_storage_blob *bsb; 43 44 bsb = bpf_inode(inode); 45 if (!bsb) 46 return NULL; 47 48 inode_storage = 49 rcu_dereference_check(bsb->storage, bpf_rcu_lock_held()); 50 if (!inode_storage) 51 return NULL; 52 53 smap = (struct bpf_local_storage_map *)map; 54 return bpf_local_storage_lookup(inode_storage, smap, cacheit_lockit); 55 } 56 57 void bpf_inode_storage_free(struct inode *inode) 58 { 59 struct bpf_local_storage *local_storage; 60 struct bpf_storage_blob *bsb; 61 62 bsb = bpf_inode(inode); 63 if (!bsb) 64 return; 65 66 rcu_read_lock(); 67 68 local_storage = rcu_dereference(bsb->storage); 69 if (!local_storage) { 70 rcu_read_unlock(); 71 return; 72 } 73 74 bpf_local_storage_destroy(local_storage); 75 rcu_read_unlock(); 76 } 77 78 static void *bpf_fd_inode_storage_lookup_elem(struct bpf_map *map, void *key) 79 { 80 struct bpf_local_storage_data *sdata; 81 struct fd f = fdget_raw(*(int *)key); 82 83 if (!f.file) 84 return ERR_PTR(-EBADF); 85 86 sdata = inode_storage_lookup(file_inode(f.file), map, true); 87 fdput(f); 88 return sdata ? sdata->data : NULL; 89 } 90 91 static long bpf_fd_inode_storage_update_elem(struct bpf_map *map, void *key, 92 void *value, u64 map_flags) 93 { 94 struct bpf_local_storage_data *sdata; 95 struct fd f = fdget_raw(*(int *)key); 96 97 if (!f.file) 98 return -EBADF; 99 if (!inode_storage_ptr(file_inode(f.file))) { 100 fdput(f); 101 return -EBADF; 102 } 103 104 sdata = bpf_local_storage_update(file_inode(f.file), 105 (struct bpf_local_storage_map *)map, 106 value, map_flags, GFP_ATOMIC); 107 fdput(f); 108 return PTR_ERR_OR_ZERO(sdata); 109 } 110 111 static int inode_storage_delete(struct inode *inode, struct bpf_map *map) 112 { 113 struct bpf_local_storage_data *sdata; 114 115 sdata = inode_storage_lookup(inode, map, false); 116 if (!sdata) 117 return -ENOENT; 118 119 bpf_selem_unlink(SELEM(sdata), false); 120 121 return 0; 122 } 123 124 static long bpf_fd_inode_storage_delete_elem(struct bpf_map *map, void *key) 125 { 126 struct fd f = fdget_raw(*(int *)key); 127 int err; 128 129 if (!f.file) 130 return -EBADF; 131 132 err = inode_storage_delete(file_inode(f.file), map); 133 fdput(f); 134 return err; 135 } 136 137 /* *gfp_flags* is a hidden argument provided by the verifier */ 138 BPF_CALL_5(bpf_inode_storage_get, struct bpf_map *, map, struct inode *, inode, 139 void *, value, u64, flags, gfp_t, gfp_flags) 140 { 141 struct bpf_local_storage_data *sdata; 142 143 WARN_ON_ONCE(!bpf_rcu_lock_held()); 144 if (flags & ~(BPF_LOCAL_STORAGE_GET_F_CREATE)) 145 return (unsigned long)NULL; 146 147 /* explicitly check that the inode_storage_ptr is not 148 * NULL as inode_storage_lookup returns NULL in this case and 149 * bpf_local_storage_update expects the owner to have a 150 * valid storage pointer. 151 */ 152 if (!inode || !inode_storage_ptr(inode)) 153 return (unsigned long)NULL; 154 155 sdata = inode_storage_lookup(inode, map, true); 156 if (sdata) 157 return (unsigned long)sdata->data; 158 159 /* This helper must only called from where the inode is guaranteed 160 * to have a refcount and cannot be freed. 161 */ 162 if (flags & BPF_LOCAL_STORAGE_GET_F_CREATE) { 163 sdata = bpf_local_storage_update( 164 inode, (struct bpf_local_storage_map *)map, value, 165 BPF_NOEXIST, gfp_flags); 166 return IS_ERR(sdata) ? (unsigned long)NULL : 167 (unsigned long)sdata->data; 168 } 169 170 return (unsigned long)NULL; 171 } 172 173 BPF_CALL_2(bpf_inode_storage_delete, 174 struct bpf_map *, map, struct inode *, inode) 175 { 176 WARN_ON_ONCE(!bpf_rcu_lock_held()); 177 if (!inode) 178 return -EINVAL; 179 180 /* This helper must only called from where the inode is guaranteed 181 * to have a refcount and cannot be freed. 182 */ 183 return inode_storage_delete(inode, map); 184 } 185 186 static int notsupp_get_next_key(struct bpf_map *map, void *key, 187 void *next_key) 188 { 189 return -ENOTSUPP; 190 } 191 192 static struct bpf_map *inode_storage_map_alloc(union bpf_attr *attr) 193 { 194 return bpf_local_storage_map_alloc(attr, &inode_cache, false); 195 } 196 197 static void inode_storage_map_free(struct bpf_map *map) 198 { 199 bpf_local_storage_map_free(map, &inode_cache, NULL); 200 } 201 202 const struct bpf_map_ops inode_storage_map_ops = { 203 .map_meta_equal = bpf_map_meta_equal, 204 .map_alloc_check = bpf_local_storage_map_alloc_check, 205 .map_alloc = inode_storage_map_alloc, 206 .map_free = inode_storage_map_free, 207 .map_get_next_key = notsupp_get_next_key, 208 .map_lookup_elem = bpf_fd_inode_storage_lookup_elem, 209 .map_update_elem = bpf_fd_inode_storage_update_elem, 210 .map_delete_elem = bpf_fd_inode_storage_delete_elem, 211 .map_check_btf = bpf_local_storage_map_check_btf, 212 .map_mem_usage = bpf_local_storage_map_mem_usage, 213 .map_btf_id = &bpf_local_storage_map_btf_id[0], 214 .map_owner_storage_ptr = inode_storage_ptr, 215 }; 216 217 BTF_ID_LIST_SINGLE(bpf_inode_storage_btf_ids, struct, inode) 218 219 const struct bpf_func_proto bpf_inode_storage_get_proto = { 220 .func = bpf_inode_storage_get, 221 .gpl_only = false, 222 .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL, 223 .arg1_type = ARG_CONST_MAP_PTR, 224 .arg2_type = ARG_PTR_TO_BTF_ID_OR_NULL, 225 .arg2_btf_id = &bpf_inode_storage_btf_ids[0], 226 .arg3_type = ARG_PTR_TO_MAP_VALUE_OR_NULL, 227 .arg4_type = ARG_ANYTHING, 228 }; 229 230 const struct bpf_func_proto bpf_inode_storage_delete_proto = { 231 .func = bpf_inode_storage_delete, 232 .gpl_only = false, 233 .ret_type = RET_INTEGER, 234 .arg1_type = ARG_CONST_MAP_PTR, 235 .arg2_type = ARG_PTR_TO_BTF_ID_OR_NULL, 236 .arg2_btf_id = &bpf_inode_storage_btf_ids[0], 237 }; 238