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 nl_policy_dump { 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 nl_policy_dump **statep, 28 const struct nla_policy *policy, 29 unsigned int maxtype) 30 { 31 struct nl_policy_dump *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 return 0; 40 41 if (!state->policies[i].policy) { 42 state->policies[i].policy = policy; 43 state->policies[i].maxtype = maxtype; 44 return 0; 45 } 46 } 47 48 n_alloc = state->n_alloc + INITIAL_POLICIES_ALLOC; 49 state = krealloc(state, struct_size(state, policies, n_alloc), 50 GFP_KERNEL); 51 if (!state) 52 return -ENOMEM; 53 54 memset(&state->policies[state->n_alloc], 0, 55 flex_array_size(state, policies, n_alloc - state->n_alloc)); 56 57 state->policies[state->n_alloc].policy = policy; 58 state->policies[state->n_alloc].maxtype = maxtype; 59 state->n_alloc = n_alloc; 60 *statep = state; 61 62 return 0; 63 } 64 65 static unsigned int get_policy_idx(struct nl_policy_dump *state, 66 const struct nla_policy *policy) 67 { 68 unsigned int i; 69 70 for (i = 0; i < state->n_alloc; i++) { 71 if (state->policies[i].policy == policy) 72 return i; 73 } 74 75 WARN_ON_ONCE(1); 76 return -1; 77 } 78 79 int netlink_policy_dump_start(const struct nla_policy *policy, 80 unsigned int maxtype, 81 unsigned long *_state) 82 { 83 struct nl_policy_dump *state; 84 unsigned int policy_idx; 85 int err; 86 87 if (*_state) 88 return 0; 89 90 /* 91 * walk the policies and nested ones first, and build 92 * a linear list of them. 93 */ 94 95 state = kzalloc(struct_size(state, policies, INITIAL_POLICIES_ALLOC), 96 GFP_KERNEL); 97 if (!state) 98 return -ENOMEM; 99 state->n_alloc = INITIAL_POLICIES_ALLOC; 100 101 err = add_policy(&state, policy, maxtype); 102 if (err) 103 return err; 104 105 for (policy_idx = 0; 106 policy_idx < state->n_alloc && state->policies[policy_idx].policy; 107 policy_idx++) { 108 const struct nla_policy *policy; 109 unsigned int type; 110 111 policy = state->policies[policy_idx].policy; 112 113 for (type = 0; 114 type <= state->policies[policy_idx].maxtype; 115 type++) { 116 switch (policy[type].type) { 117 case NLA_NESTED: 118 case NLA_NESTED_ARRAY: 119 err = add_policy(&state, 120 policy[type].nested_policy, 121 policy[type].len); 122 if (err) 123 return err; 124 break; 125 default: 126 break; 127 } 128 } 129 } 130 131 *_state = (unsigned long)state; 132 133 return 0; 134 } 135 136 static bool netlink_policy_dump_finished(struct nl_policy_dump *state) 137 { 138 return state->policy_idx >= state->n_alloc || 139 !state->policies[state->policy_idx].policy; 140 } 141 142 bool netlink_policy_dump_loop(unsigned long _state) 143 { 144 struct nl_policy_dump *state = (void *)_state; 145 146 return !netlink_policy_dump_finished(state); 147 } 148 149 int netlink_policy_dump_write(struct sk_buff *skb, unsigned long _state) 150 { 151 struct nl_policy_dump *state = (void *)_state; 152 const struct nla_policy *pt; 153 struct nlattr *policy, *attr; 154 enum netlink_attribute_type type; 155 bool again; 156 157 send_attribute: 158 again = false; 159 160 pt = &state->policies[state->policy_idx].policy[state->attr_idx]; 161 162 policy = nla_nest_start(skb, state->policy_idx); 163 if (!policy) 164 return -ENOBUFS; 165 166 attr = nla_nest_start(skb, state->attr_idx); 167 if (!attr) 168 goto nla_put_failure; 169 170 switch (pt->type) { 171 default: 172 case NLA_UNSPEC: 173 case NLA_REJECT: 174 /* skip - use NLA_MIN_LEN to advertise such */ 175 nla_nest_cancel(skb, policy); 176 again = true; 177 goto next; 178 case NLA_NESTED: 179 type = NL_ATTR_TYPE_NESTED; 180 fallthrough; 181 case NLA_NESTED_ARRAY: 182 if (pt->type == NLA_NESTED_ARRAY) 183 type = NL_ATTR_TYPE_NESTED_ARRAY; 184 if (pt->nested_policy && pt->len && 185 (nla_put_u32(skb, NL_POLICY_TYPE_ATTR_POLICY_IDX, 186 get_policy_idx(state, pt->nested_policy)) || 187 nla_put_u32(skb, NL_POLICY_TYPE_ATTR_POLICY_MAXTYPE, 188 pt->len))) 189 goto nla_put_failure; 190 break; 191 case NLA_U8: 192 case NLA_U16: 193 case NLA_U32: 194 case NLA_U64: 195 case NLA_MSECS: { 196 struct netlink_range_validation range; 197 198 if (pt->type == NLA_U8) 199 type = NL_ATTR_TYPE_U8; 200 else if (pt->type == NLA_U16) 201 type = NL_ATTR_TYPE_U16; 202 else if (pt->type == NLA_U32) 203 type = NL_ATTR_TYPE_U32; 204 else 205 type = NL_ATTR_TYPE_U64; 206 207 nla_get_range_unsigned(pt, &range); 208 209 if (nla_put_u64_64bit(skb, NL_POLICY_TYPE_ATTR_MIN_VALUE_U, 210 range.min, NL_POLICY_TYPE_ATTR_PAD) || 211 nla_put_u64_64bit(skb, NL_POLICY_TYPE_ATTR_MAX_VALUE_U, 212 range.max, NL_POLICY_TYPE_ATTR_PAD)) 213 goto nla_put_failure; 214 break; 215 } 216 case NLA_S8: 217 case NLA_S16: 218 case NLA_S32: 219 case NLA_S64: { 220 struct netlink_range_validation_signed range; 221 222 if (pt->type == NLA_S8) 223 type = NL_ATTR_TYPE_S8; 224 else if (pt->type == NLA_S16) 225 type = NL_ATTR_TYPE_S16; 226 else if (pt->type == NLA_S32) 227 type = NL_ATTR_TYPE_S32; 228 else 229 type = NL_ATTR_TYPE_S64; 230 231 nla_get_range_signed(pt, &range); 232 233 if (nla_put_s64(skb, NL_POLICY_TYPE_ATTR_MIN_VALUE_S, 234 range.min, NL_POLICY_TYPE_ATTR_PAD) || 235 nla_put_s64(skb, NL_POLICY_TYPE_ATTR_MAX_VALUE_S, 236 range.max, NL_POLICY_TYPE_ATTR_PAD)) 237 goto nla_put_failure; 238 break; 239 } 240 case NLA_BITFIELD32: 241 type = NL_ATTR_TYPE_BITFIELD32; 242 if (nla_put_u32(skb, NL_POLICY_TYPE_ATTR_BITFIELD32_MASK, 243 pt->bitfield32_valid)) 244 goto nla_put_failure; 245 break; 246 case NLA_EXACT_LEN: 247 type = NL_ATTR_TYPE_BINARY; 248 if (nla_put_u32(skb, NL_POLICY_TYPE_ATTR_MIN_LENGTH, pt->len) || 249 nla_put_u32(skb, NL_POLICY_TYPE_ATTR_MAX_LENGTH, pt->len)) 250 goto nla_put_failure; 251 break; 252 case NLA_STRING: 253 case NLA_NUL_STRING: 254 case NLA_BINARY: 255 if (pt->type == NLA_STRING) 256 type = NL_ATTR_TYPE_STRING; 257 else if (pt->type == NLA_NUL_STRING) 258 type = NL_ATTR_TYPE_NUL_STRING; 259 else 260 type = NL_ATTR_TYPE_BINARY; 261 if (pt->len && nla_put_u32(skb, NL_POLICY_TYPE_ATTR_MAX_LENGTH, 262 pt->len)) 263 goto nla_put_failure; 264 break; 265 case NLA_MIN_LEN: 266 type = NL_ATTR_TYPE_BINARY; 267 if (nla_put_u32(skb, NL_POLICY_TYPE_ATTR_MIN_LENGTH, pt->len)) 268 goto nla_put_failure; 269 break; 270 case NLA_FLAG: 271 type = NL_ATTR_TYPE_FLAG; 272 break; 273 } 274 275 if (nla_put_u32(skb, NL_POLICY_TYPE_ATTR_TYPE, type)) 276 goto nla_put_failure; 277 278 /* finish and move state to next attribute */ 279 nla_nest_end(skb, attr); 280 nla_nest_end(skb, policy); 281 282 next: 283 state->attr_idx += 1; 284 if (state->attr_idx > state->policies[state->policy_idx].maxtype) { 285 state->attr_idx = 0; 286 state->policy_idx++; 287 } 288 289 if (again) { 290 if (netlink_policy_dump_finished(state)) 291 return -ENODATA; 292 goto send_attribute; 293 } 294 295 return 0; 296 297 nla_put_failure: 298 nla_nest_cancel(skb, policy); 299 return -ENOBUFS; 300 } 301 302 void netlink_policy_dump_free(unsigned long _state) 303 { 304 struct nl_policy_dump *state = (void *)_state; 305 306 kfree(state); 307 } 308