1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Pkey table 4 * 5 * SELinux must keep a mapping of Infinband PKEYs to labels/SIDs. This 6 * mapping is maintained as part of the normal policy but a fast cache is 7 * needed to reduce the lookup overhead. 8 * 9 * This code is heavily based on the "netif" and "netport" concept originally 10 * developed by 11 * James Morris <jmorris@redhat.com> and 12 * Paul Moore <paul@paul-moore.com> 13 * (see security/selinux/netif.c and security/selinux/netport.c for more 14 * information) 15 */ 16 17 /* 18 * (c) Mellanox Technologies, 2016 19 */ 20 21 #include <linux/types.h> 22 #include <linux/rcupdate.h> 23 #include <linux/list.h> 24 #include <linux/spinlock.h> 25 26 #include "ibpkey.h" 27 #include "objsec.h" 28 29 #define SEL_PKEY_HASH_SIZE 256 30 #define SEL_PKEY_HASH_BKT_LIMIT 16 31 32 struct sel_ib_pkey_bkt { 33 int size; 34 struct list_head list; 35 }; 36 37 struct sel_ib_pkey { 38 struct pkey_security_struct psec; 39 struct list_head list; 40 struct rcu_head rcu; 41 }; 42 43 static DEFINE_SPINLOCK(sel_ib_pkey_lock); 44 static struct sel_ib_pkey_bkt sel_ib_pkey_hash[SEL_PKEY_HASH_SIZE]; 45 46 /** 47 * sel_ib_pkey_hashfn - Hashing function for the pkey table 48 * @pkey: pkey number 49 * 50 * Description: 51 * This is the hashing function for the pkey table, it returns the bucket 52 * number for the given pkey. 53 * 54 */ 55 static unsigned int sel_ib_pkey_hashfn(u16 pkey) 56 { 57 return (pkey & (SEL_PKEY_HASH_SIZE - 1)); 58 } 59 60 /** 61 * sel_ib_pkey_find - Search for a pkey record 62 * @subnet_prefix: subnet_prefix 63 * @pkey_num: pkey_num 64 * 65 * Description: 66 * Search the pkey table and return the matching record. If an entry 67 * can not be found in the table return NULL. 68 * 69 */ 70 static struct sel_ib_pkey *sel_ib_pkey_find(u64 subnet_prefix, u16 pkey_num) 71 { 72 unsigned int idx; 73 struct sel_ib_pkey *pkey; 74 75 idx = sel_ib_pkey_hashfn(pkey_num); 76 list_for_each_entry_rcu(pkey, &sel_ib_pkey_hash[idx].list, list) { 77 if (pkey->psec.pkey == pkey_num && 78 pkey->psec.subnet_prefix == subnet_prefix) 79 return pkey; 80 } 81 82 return NULL; 83 } 84 85 /** 86 * sel_ib_pkey_insert - Insert a new pkey into the table 87 * @pkey: the new pkey record 88 * 89 * Description: 90 * Add a new pkey record to the hash table. 91 * 92 */ 93 static void sel_ib_pkey_insert(struct sel_ib_pkey *pkey) 94 { 95 unsigned int idx; 96 97 /* we need to impose a limit on the growth of the hash table so check 98 * this bucket to make sure it is within the specified bounds 99 */ 100 idx = sel_ib_pkey_hashfn(pkey->psec.pkey); 101 list_add_rcu(&pkey->list, &sel_ib_pkey_hash[idx].list); 102 if (sel_ib_pkey_hash[idx].size == SEL_PKEY_HASH_BKT_LIMIT) { 103 struct sel_ib_pkey *tail; 104 105 tail = list_entry( 106 rcu_dereference_protected( 107 list_tail_rcu(&sel_ib_pkey_hash[idx].list), 108 lockdep_is_held(&sel_ib_pkey_lock)), 109 struct sel_ib_pkey, list); 110 list_del_rcu(&tail->list); 111 kfree_rcu(tail, rcu); 112 } else { 113 sel_ib_pkey_hash[idx].size++; 114 } 115 } 116 117 /** 118 * sel_ib_pkey_sid_slow - Lookup the SID of a pkey using the policy 119 * @subnet_prefix: subnet prefix 120 * @pkey_num: pkey number 121 * @sid: pkey SID 122 * 123 * Description: 124 * This function determines the SID of a pkey by querying the security 125 * policy. The result is added to the pkey table to speedup future 126 * queries. Returns zero on success, negative values on failure. 127 * 128 */ 129 static int sel_ib_pkey_sid_slow(u64 subnet_prefix, u16 pkey_num, u32 *sid) 130 { 131 int ret; 132 struct sel_ib_pkey *pkey; 133 struct sel_ib_pkey *new = NULL; 134 unsigned long flags; 135 136 spin_lock_irqsave(&sel_ib_pkey_lock, flags); 137 pkey = sel_ib_pkey_find(subnet_prefix, pkey_num); 138 if (pkey) { 139 *sid = pkey->psec.sid; 140 spin_unlock_irqrestore(&sel_ib_pkey_lock, flags); 141 return 0; 142 } 143 144 ret = security_ib_pkey_sid(subnet_prefix, pkey_num, 145 sid); 146 if (ret) 147 goto out; 148 149 /* If this memory allocation fails still return 0. The SID 150 * is valid, it just won't be added to the cache. 151 */ 152 new = kzalloc(sizeof(*new), GFP_ATOMIC); 153 if (!new) { 154 ret = -ENOMEM; 155 goto out; 156 } 157 158 new->psec.subnet_prefix = subnet_prefix; 159 new->psec.pkey = pkey_num; 160 new->psec.sid = *sid; 161 sel_ib_pkey_insert(new); 162 163 out: 164 spin_unlock_irqrestore(&sel_ib_pkey_lock, flags); 165 return ret; 166 } 167 168 /** 169 * sel_ib_pkey_sid - Lookup the SID of a PKEY 170 * @subnet_prefix: subnet_prefix 171 * @pkey_num: pkey number 172 * @sid: pkey SID 173 * 174 * Description: 175 * This function determines the SID of a PKEY using the fastest method 176 * possible. First the pkey table is queried, but if an entry can't be found 177 * then the policy is queried and the result is added to the table to speedup 178 * future queries. Returns zero on success, negative values on failure. 179 * 180 */ 181 int sel_ib_pkey_sid(u64 subnet_prefix, u16 pkey_num, u32 *sid) 182 { 183 struct sel_ib_pkey *pkey; 184 185 rcu_read_lock(); 186 pkey = sel_ib_pkey_find(subnet_prefix, pkey_num); 187 if (pkey) { 188 *sid = pkey->psec.sid; 189 rcu_read_unlock(); 190 return 0; 191 } 192 rcu_read_unlock(); 193 194 return sel_ib_pkey_sid_slow(subnet_prefix, pkey_num, sid); 195 } 196 197 /** 198 * sel_ib_pkey_flush - Flush the entire pkey table 199 * 200 * Description: 201 * Remove all entries from the pkey table 202 * 203 */ 204 void sel_ib_pkey_flush(void) 205 { 206 unsigned int idx; 207 struct sel_ib_pkey *pkey, *pkey_tmp; 208 unsigned long flags; 209 210 spin_lock_irqsave(&sel_ib_pkey_lock, flags); 211 for (idx = 0; idx < SEL_PKEY_HASH_SIZE; idx++) { 212 list_for_each_entry_safe(pkey, pkey_tmp, 213 &sel_ib_pkey_hash[idx].list, list) { 214 list_del_rcu(&pkey->list); 215 kfree_rcu(pkey, rcu); 216 } 217 sel_ib_pkey_hash[idx].size = 0; 218 } 219 spin_unlock_irqrestore(&sel_ib_pkey_lock, flags); 220 } 221 222 static __init int sel_ib_pkey_init(void) 223 { 224 int iter; 225 226 if (!selinux_enabled_boot) 227 return 0; 228 229 for (iter = 0; iter < SEL_PKEY_HASH_SIZE; iter++) { 230 INIT_LIST_HEAD(&sel_ib_pkey_hash[iter].list); 231 sel_ib_pkey_hash[iter].size = 0; 232 } 233 234 return 0; 235 } 236 237 subsys_initcall(sel_ib_pkey_init); 238