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 LIST_HEAD(sel_ib_pkey_list); 44 static DEFINE_SPINLOCK(sel_ib_pkey_lock); 45 static struct sel_ib_pkey_bkt sel_ib_pkey_hash[SEL_PKEY_HASH_SIZE]; 46 47 /** 48 * sel_ib_pkey_hashfn - Hashing function for the pkey table 49 * @pkey: pkey number 50 * 51 * Description: 52 * This is the hashing function for the pkey table, it returns the bucket 53 * number for the given pkey. 54 * 55 */ 56 static unsigned int sel_ib_pkey_hashfn(u16 pkey) 57 { 58 return (pkey & (SEL_PKEY_HASH_SIZE - 1)); 59 } 60 61 /** 62 * sel_ib_pkey_find - Search for a pkey record 63 * @subnet_prefix: subnet_prefix 64 * @pkey_num: pkey_num 65 * 66 * Description: 67 * Search the pkey table and return the matching record. If an entry 68 * can not be found in the table return NULL. 69 * 70 */ 71 static struct sel_ib_pkey *sel_ib_pkey_find(u64 subnet_prefix, u16 pkey_num) 72 { 73 unsigned int idx; 74 struct sel_ib_pkey *pkey; 75 76 idx = sel_ib_pkey_hashfn(pkey_num); 77 list_for_each_entry_rcu(pkey, &sel_ib_pkey_hash[idx].list, list) { 78 if (pkey->psec.pkey == pkey_num && 79 pkey->psec.subnet_prefix == subnet_prefix) 80 return pkey; 81 } 82 83 return NULL; 84 } 85 86 /** 87 * sel_ib_pkey_insert - Insert a new pkey into the table 88 * @pkey: the new pkey record 89 * 90 * Description: 91 * Add a new pkey record to the hash table. 92 * 93 */ 94 static void sel_ib_pkey_insert(struct sel_ib_pkey *pkey) 95 { 96 unsigned int idx; 97 98 /* we need to impose a limit on the growth of the hash table so check 99 * this bucket to make sure it is within the specified bounds 100 */ 101 idx = sel_ib_pkey_hashfn(pkey->psec.pkey); 102 list_add_rcu(&pkey->list, &sel_ib_pkey_hash[idx].list); 103 if (sel_ib_pkey_hash[idx].size == SEL_PKEY_HASH_BKT_LIMIT) { 104 struct sel_ib_pkey *tail; 105 106 tail = list_entry( 107 rcu_dereference_protected( 108 sel_ib_pkey_hash[idx].list.prev, 109 lockdep_is_held(&sel_ib_pkey_lock)), 110 struct sel_ib_pkey, list); 111 list_del_rcu(&tail->list); 112 kfree_rcu(tail, rcu); 113 } else { 114 sel_ib_pkey_hash[idx].size++; 115 } 116 } 117 118 /** 119 * sel_ib_pkey_sid_slow - Lookup the SID of a pkey using the policy 120 * @subnet_prefix: subnet prefix 121 * @pkey_num: pkey number 122 * @sid: pkey SID 123 * 124 * Description: 125 * This function determines the SID of a pkey by querying the security 126 * policy. The result is added to the pkey table to speedup future 127 * queries. Returns zero on success, negative values on failure. 128 * 129 */ 130 static int sel_ib_pkey_sid_slow(u64 subnet_prefix, u16 pkey_num, u32 *sid) 131 { 132 int ret; 133 struct sel_ib_pkey *pkey; 134 struct sel_ib_pkey *new = NULL; 135 unsigned long flags; 136 137 spin_lock_irqsave(&sel_ib_pkey_lock, flags); 138 pkey = sel_ib_pkey_find(subnet_prefix, pkey_num); 139 if (pkey) { 140 *sid = pkey->psec.sid; 141 spin_unlock_irqrestore(&sel_ib_pkey_lock, flags); 142 return 0; 143 } 144 145 ret = security_ib_pkey_sid(&selinux_state, subnet_prefix, pkey_num, 146 sid); 147 if (ret) 148 goto out; 149 150 /* If this memory allocation fails still return 0. The SID 151 * is valid, it just won't be added to the cache. 152 */ 153 new = kzalloc(sizeof(*new), GFP_ATOMIC); 154 if (!new) 155 goto out; 156 157 new->psec.subnet_prefix = subnet_prefix; 158 new->psec.pkey = pkey_num; 159 new->psec.sid = *sid; 160 sel_ib_pkey_insert(new); 161 162 out: 163 spin_unlock_irqrestore(&sel_ib_pkey_lock, flags); 164 return ret; 165 } 166 167 /** 168 * sel_ib_pkey_sid - Lookup the SID of a PKEY 169 * @subnet_prefix: subnet_prefix 170 * @pkey_num: pkey number 171 * @sid: pkey SID 172 * 173 * Description: 174 * This function determines the SID of a PKEY using the fastest method 175 * possible. First the pkey table is queried, but if an entry can't be found 176 * then the policy is queried and the result is added to the table to speedup 177 * future queries. Returns zero on success, negative values on failure. 178 * 179 */ 180 int sel_ib_pkey_sid(u64 subnet_prefix, u16 pkey_num, u32 *sid) 181 { 182 struct sel_ib_pkey *pkey; 183 184 rcu_read_lock(); 185 pkey = sel_ib_pkey_find(subnet_prefix, pkey_num); 186 if (pkey) { 187 *sid = pkey->psec.sid; 188 rcu_read_unlock(); 189 return 0; 190 } 191 rcu_read_unlock(); 192 193 return sel_ib_pkey_sid_slow(subnet_prefix, pkey_num, sid); 194 } 195 196 /** 197 * sel_ib_pkey_flush - Flush the entire pkey table 198 * 199 * Description: 200 * Remove all entries from the pkey table 201 * 202 */ 203 void sel_ib_pkey_flush(void) 204 { 205 unsigned int idx; 206 struct sel_ib_pkey *pkey, *pkey_tmp; 207 unsigned long flags; 208 209 spin_lock_irqsave(&sel_ib_pkey_lock, flags); 210 for (idx = 0; idx < SEL_PKEY_HASH_SIZE; idx++) { 211 list_for_each_entry_safe(pkey, pkey_tmp, 212 &sel_ib_pkey_hash[idx].list, list) { 213 list_del_rcu(&pkey->list); 214 kfree_rcu(pkey, rcu); 215 } 216 sel_ib_pkey_hash[idx].size = 0; 217 } 218 spin_unlock_irqrestore(&sel_ib_pkey_lock, flags); 219 } 220 221 static __init int sel_ib_pkey_init(void) 222 { 223 int iter; 224 225 if (!selinux_enabled_boot) 226 return 0; 227 228 for (iter = 0; iter < SEL_PKEY_HASH_SIZE; iter++) { 229 INIT_LIST_HEAD(&sel_ib_pkey_hash[iter].list); 230 sel_ib_pkey_hash[iter].size = 0; 231 } 232 233 return 0; 234 } 235 236 subsys_initcall(sel_ib_pkey_init); 237