1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * NETLINK Policy advertisement to userspace 4 * 5 * Authors: Johannes Berg <johannes@sipsolutions.net> 6 * 7 * Copyright 2019 Intel Corporation 8 */ 9 10 #include <linux/kernel.h> 11 #include <linux/errno.h> 12 #include <linux/types.h> 13 #include <net/netlink.h> 14 15 #define INITIAL_POLICIES_ALLOC 10 16 17 struct netlink_policy_dump_state { 18 unsigned int policy_idx; 19 unsigned int attr_idx; 20 unsigned int n_alloc; 21 struct { 22 const struct nla_policy *policy; 23 unsigned int maxtype; 24 } policies[]; 25 }; 26 27 static int add_policy(struct netlink_policy_dump_state **statep, 28 const struct nla_policy *policy, 29 unsigned int maxtype) 30 { 31 struct netlink_policy_dump_state *state = *statep; 32 unsigned int n_alloc, i; 33 34 if (!policy || !maxtype) 35 return 0; 36 37 for (i = 0; i < state->n_alloc; i++) { 38 if (state->policies[i].policy == policy && 39 state->policies[i].maxtype == maxtype) 40 return 0; 41 42 if (!state->policies[i].policy) { 43 state->policies[i].policy = policy; 44 state->policies[i].maxtype = maxtype; 45 return 0; 46 } 47 } 48 49 n_alloc = state->n_alloc + INITIAL_POLICIES_ALLOC; 50 state = krealloc(state, struct_size(state, policies, n_alloc), 51 GFP_KERNEL); 52 if (!state) 53 return -ENOMEM; 54 55 memset(&state->policies[state->n_alloc], 0, 56 flex_array_size(state, policies, n_alloc - state->n_alloc)); 57 58 state->policies[state->n_alloc].policy = policy; 59 state->policies[state->n_alloc].maxtype = maxtype; 60 state->n_alloc = n_alloc; 61 *statep = state; 62 63 return 0; 64 } 65 66 /** 67 * netlink_policy_dump_get_policy_idx - retrieve policy index 68 * @state: the policy dump state 69 * @policy: the policy to find 70 * @maxtype: the policy's maxattr 71 * 72 * Returns: the index of the given policy in the dump state 73 * 74 * Call this to find a policy index when you've added multiple and e.g. 75 * need to tell userspace which command has which policy (by index). 76 * 77 * Note: this will WARN and return 0 if the policy isn't found, which 78 * means it wasn't added in the first place, which would be an 79 * internal consistency bug. 80 */ 81 int netlink_policy_dump_get_policy_idx(struct netlink_policy_dump_state *state, 82 const struct nla_policy *policy, 83 unsigned int maxtype) 84 { 85 unsigned int i; 86 87 if (WARN_ON(!policy || !maxtype)) 88 return 0; 89 90 for (i = 0; i < state->n_alloc; i++) { 91 if (state->policies[i].policy == policy && 92 state->policies[i].maxtype == maxtype) 93 return i; 94 } 95 96 WARN_ON(1); 97 return 0; 98 } 99 100 static struct netlink_policy_dump_state *alloc_state(void) 101 { 102 struct netlink_policy_dump_state *state; 103 104 state = kzalloc(struct_size(state, policies, INITIAL_POLICIES_ALLOC), 105 GFP_KERNEL); 106 if (!state) 107 return ERR_PTR(-ENOMEM); 108 state->n_alloc = INITIAL_POLICIES_ALLOC; 109 110 return state; 111 } 112 113 /** 114 * netlink_policy_dump_add_policy - add a policy to the dump 115 * @pstate: state to add to, may be reallocated, must be %NULL the first time 116 * @policy: the new policy to add to the dump 117 * @maxtype: the new policy's max attr type 118 * 119 * Returns: 0 on success, a negative error code otherwise. 120 * 121 * Call this to allocate a policy dump state, and to add policies to it. This 122 * should be called from the dump start() callback. 123 * 124 * Note: on failures, any previously allocated state is freed. 125 */ 126 int netlink_policy_dump_add_policy(struct netlink_policy_dump_state **pstate, 127 const struct nla_policy *policy, 128 unsigned int maxtype) 129 { 130 struct netlink_policy_dump_state *state = *pstate; 131 unsigned int policy_idx; 132 int err; 133 134 if (!state) { 135 state = alloc_state(); 136 if (IS_ERR(state)) 137 return PTR_ERR(state); 138 } 139 140 /* 141 * walk the policies and nested ones first, and build 142 * a linear list of them. 143 */ 144 145 err = add_policy(&state, policy, maxtype); 146 if (err) 147 return err; 148 149 for (policy_idx = 0; 150 policy_idx < state->n_alloc && state->policies[policy_idx].policy; 151 policy_idx++) { 152 const struct nla_policy *policy; 153 unsigned int type; 154 155 policy = state->policies[policy_idx].policy; 156 157 for (type = 0; 158 type <= state->policies[policy_idx].maxtype; 159 type++) { 160 switch (policy[type].type) { 161 case NLA_NESTED: 162 case NLA_NESTED_ARRAY: 163 err = add_policy(&state, 164 policy[type].nested_policy, 165 policy[type].len); 166 if (err) 167 return err; 168 break; 169 default: 170 break; 171 } 172 } 173 } 174 175 *pstate = state; 176 return 0; 177 } 178 179 static bool 180 netlink_policy_dump_finished(struct netlink_policy_dump_state *state) 181 { 182 return state->policy_idx >= state->n_alloc || 183 !state->policies[state->policy_idx].policy; 184 } 185 186 /** 187 * netlink_policy_dump_loop - dumping loop indicator 188 * @state: the policy dump state 189 * 190 * Returns: %true if the dump continues, %false otherwise 191 * 192 * Note: this frees the dump state when finishing 193 */ 194 bool netlink_policy_dump_loop(struct netlink_policy_dump_state *state) 195 { 196 return !netlink_policy_dump_finished(state); 197 } 198 199 /** 200 * netlink_policy_dump_write - write current policy dump attributes 201 * @skb: the message skb to write to 202 * @state: the policy dump state 203 * 204 * Returns: 0 on success, an error code otherwise 205 */ 206 int netlink_policy_dump_write(struct sk_buff *skb, 207 struct netlink_policy_dump_state *state) 208 { 209 const struct nla_policy *pt; 210 struct nlattr *policy, *attr; 211 enum netlink_attribute_type type; 212 bool again; 213 214 send_attribute: 215 again = false; 216 217 pt = &state->policies[state->policy_idx].policy[state->attr_idx]; 218 219 policy = nla_nest_start(skb, state->policy_idx); 220 if (!policy) 221 return -ENOBUFS; 222 223 attr = nla_nest_start(skb, state->attr_idx); 224 if (!attr) 225 goto nla_put_failure; 226 227 switch (pt->type) { 228 default: 229 case NLA_UNSPEC: 230 case NLA_REJECT: 231 /* skip - use NLA_MIN_LEN to advertise such */ 232 nla_nest_cancel(skb, policy); 233 again = true; 234 goto next; 235 case NLA_NESTED: 236 type = NL_ATTR_TYPE_NESTED; 237 fallthrough; 238 case NLA_NESTED_ARRAY: 239 if (pt->type == NLA_NESTED_ARRAY) 240 type = NL_ATTR_TYPE_NESTED_ARRAY; 241 if (pt->nested_policy && pt->len && 242 (nla_put_u32(skb, NL_POLICY_TYPE_ATTR_POLICY_IDX, 243 netlink_policy_dump_get_policy_idx(state, 244 pt->nested_policy, 245 pt->len)) || 246 nla_put_u32(skb, NL_POLICY_TYPE_ATTR_POLICY_MAXTYPE, 247 pt->len))) 248 goto nla_put_failure; 249 break; 250 case NLA_U8: 251 case NLA_U16: 252 case NLA_U32: 253 case NLA_U64: 254 case NLA_MSECS: { 255 struct netlink_range_validation range; 256 257 if (pt->type == NLA_U8) 258 type = NL_ATTR_TYPE_U8; 259 else if (pt->type == NLA_U16) 260 type = NL_ATTR_TYPE_U16; 261 else if (pt->type == NLA_U32) 262 type = NL_ATTR_TYPE_U32; 263 else 264 type = NL_ATTR_TYPE_U64; 265 266 if (pt->validation_type == NLA_VALIDATE_MASK) { 267 if (nla_put_u64_64bit(skb, NL_POLICY_TYPE_ATTR_MASK, 268 pt->mask, 269 NL_POLICY_TYPE_ATTR_PAD)) 270 goto nla_put_failure; 271 break; 272 } 273 274 nla_get_range_unsigned(pt, &range); 275 276 if (nla_put_u64_64bit(skb, NL_POLICY_TYPE_ATTR_MIN_VALUE_U, 277 range.min, NL_POLICY_TYPE_ATTR_PAD) || 278 nla_put_u64_64bit(skb, NL_POLICY_TYPE_ATTR_MAX_VALUE_U, 279 range.max, NL_POLICY_TYPE_ATTR_PAD)) 280 goto nla_put_failure; 281 break; 282 } 283 case NLA_S8: 284 case NLA_S16: 285 case NLA_S32: 286 case NLA_S64: { 287 struct netlink_range_validation_signed range; 288 289 if (pt->type == NLA_S8) 290 type = NL_ATTR_TYPE_S8; 291 else if (pt->type == NLA_S16) 292 type = NL_ATTR_TYPE_S16; 293 else if (pt->type == NLA_S32) 294 type = NL_ATTR_TYPE_S32; 295 else 296 type = NL_ATTR_TYPE_S64; 297 298 nla_get_range_signed(pt, &range); 299 300 if (nla_put_s64(skb, NL_POLICY_TYPE_ATTR_MIN_VALUE_S, 301 range.min, NL_POLICY_TYPE_ATTR_PAD) || 302 nla_put_s64(skb, NL_POLICY_TYPE_ATTR_MAX_VALUE_S, 303 range.max, NL_POLICY_TYPE_ATTR_PAD)) 304 goto nla_put_failure; 305 break; 306 } 307 case NLA_BITFIELD32: 308 type = NL_ATTR_TYPE_BITFIELD32; 309 if (nla_put_u32(skb, NL_POLICY_TYPE_ATTR_BITFIELD32_MASK, 310 pt->bitfield32_valid)) 311 goto nla_put_failure; 312 break; 313 case NLA_STRING: 314 case NLA_NUL_STRING: 315 case NLA_BINARY: 316 if (pt->type == NLA_STRING) 317 type = NL_ATTR_TYPE_STRING; 318 else if (pt->type == NLA_NUL_STRING) 319 type = NL_ATTR_TYPE_NUL_STRING; 320 else 321 type = NL_ATTR_TYPE_BINARY; 322 323 if (pt->validation_type == NLA_VALIDATE_RANGE || 324 pt->validation_type == NLA_VALIDATE_RANGE_WARN_TOO_LONG) { 325 struct netlink_range_validation range; 326 327 nla_get_range_unsigned(pt, &range); 328 329 if (range.min && 330 nla_put_u32(skb, NL_POLICY_TYPE_ATTR_MIN_LENGTH, 331 range.min)) 332 goto nla_put_failure; 333 334 if (range.max < U16_MAX && 335 nla_put_u32(skb, NL_POLICY_TYPE_ATTR_MAX_LENGTH, 336 range.max)) 337 goto nla_put_failure; 338 } else if (pt->len && 339 nla_put_u32(skb, NL_POLICY_TYPE_ATTR_MAX_LENGTH, 340 pt->len)) { 341 goto nla_put_failure; 342 } 343 break; 344 case NLA_FLAG: 345 type = NL_ATTR_TYPE_FLAG; 346 break; 347 } 348 349 if (nla_put_u32(skb, NL_POLICY_TYPE_ATTR_TYPE, type)) 350 goto nla_put_failure; 351 352 /* finish and move state to next attribute */ 353 nla_nest_end(skb, attr); 354 nla_nest_end(skb, policy); 355 356 next: 357 state->attr_idx += 1; 358 if (state->attr_idx > state->policies[state->policy_idx].maxtype) { 359 state->attr_idx = 0; 360 state->policy_idx++; 361 } 362 363 if (again) { 364 if (netlink_policy_dump_finished(state)) 365 return -ENODATA; 366 goto send_attribute; 367 } 368 369 return 0; 370 371 nla_put_failure: 372 nla_nest_cancel(skb, policy); 373 return -ENOBUFS; 374 } 375 376 /** 377 * netlink_policy_dump_free - free policy dump state 378 * @state: the policy dump state to free 379 * 380 * Call this from the done() method to ensure dump state is freed. 381 */ 382 void netlink_policy_dump_free(struct netlink_policy_dump_state *state) 383 { 384 kfree(state); 385 } 386