diff options
Diffstat (limited to 'security/selinux/ibpkey.c')
| -rw-r--r-- | security/selinux/ibpkey.c | 238 |
1 files changed, 238 insertions, 0 deletions
diff --git a/security/selinux/ibpkey.c b/security/selinux/ibpkey.c new file mode 100644 index 000000000..3a63a989e --- /dev/null +++ b/security/selinux/ibpkey.c @@ -0,0 +1,238 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Pkey table + * + * SELinux must keep a mapping of Infinband PKEYs to labels/SIDs. This + * mapping is maintained as part of the normal policy but a fast cache is + * needed to reduce the lookup overhead. + * + * This code is heavily based on the "netif" and "netport" concept originally + * developed by + * James Morris <jmorris@redhat.com> and + * Paul Moore <paul@paul-moore.com> + * (see security/selinux/netif.c and security/selinux/netport.c for more + * information) + */ + +/* + * (c) Mellanox Technologies, 2016 + */ + +#include <linux/types.h> +#include <linux/rcupdate.h> +#include <linux/list.h> +#include <linux/spinlock.h> + +#include "ibpkey.h" +#include "objsec.h" + +#define SEL_PKEY_HASH_SIZE 256 +#define SEL_PKEY_HASH_BKT_LIMIT 16 + +struct sel_ib_pkey_bkt { + int size; + struct list_head list; +}; + +struct sel_ib_pkey { + struct pkey_security_struct psec; + struct list_head list; + struct rcu_head rcu; +}; + +static LIST_HEAD(sel_ib_pkey_list); +static DEFINE_SPINLOCK(sel_ib_pkey_lock); +static struct sel_ib_pkey_bkt sel_ib_pkey_hash[SEL_PKEY_HASH_SIZE]; + +/** + * sel_ib_pkey_hashfn - Hashing function for the pkey table + * @pkey: pkey number + * + * Description: + * This is the hashing function for the pkey table, it returns the bucket + * number for the given pkey. + * + */ +static unsigned int sel_ib_pkey_hashfn(u16 pkey) +{ + return (pkey & (SEL_PKEY_HASH_SIZE - 1)); +} + +/** + * sel_ib_pkey_find - Search for a pkey record + * @subnet_prefix: subnet_prefix + * @pkey_num: pkey_num + * + * Description: + * Search the pkey table and return the matching record. If an entry + * can not be found in the table return NULL. + * + */ +static struct sel_ib_pkey *sel_ib_pkey_find(u64 subnet_prefix, u16 pkey_num) +{ + unsigned int idx; + struct sel_ib_pkey *pkey; + + idx = sel_ib_pkey_hashfn(pkey_num); + list_for_each_entry_rcu(pkey, &sel_ib_pkey_hash[idx].list, list) { + if (pkey->psec.pkey == pkey_num && + pkey->psec.subnet_prefix == subnet_prefix) + return pkey; + } + + return NULL; +} + +/** + * sel_ib_pkey_insert - Insert a new pkey into the table + * @pkey: the new pkey record + * + * Description: + * Add a new pkey record to the hash table. + * + */ +static void sel_ib_pkey_insert(struct sel_ib_pkey *pkey) +{ + unsigned int idx; + + /* we need to impose a limit on the growth of the hash table so check + * this bucket to make sure it is within the specified bounds + */ + idx = sel_ib_pkey_hashfn(pkey->psec.pkey); + list_add_rcu(&pkey->list, &sel_ib_pkey_hash[idx].list); + if (sel_ib_pkey_hash[idx].size == SEL_PKEY_HASH_BKT_LIMIT) { + struct sel_ib_pkey *tail; + + tail = list_entry( + rcu_dereference_protected( + sel_ib_pkey_hash[idx].list.prev, + lockdep_is_held(&sel_ib_pkey_lock)), + struct sel_ib_pkey, list); + list_del_rcu(&tail->list); + kfree_rcu(tail, rcu); + } else { + sel_ib_pkey_hash[idx].size++; + } +} + +/** + * sel_ib_pkey_sid_slow - Lookup the SID of a pkey using the policy + * @subnet_prefix: subnet prefix + * @pkey_num: pkey number + * @sid: pkey SID + * + * Description: + * This function determines the SID of a pkey by querying the security + * policy. The result is added to the pkey table to speedup future + * queries. Returns zero on success, negative values on failure. + * + */ +static int sel_ib_pkey_sid_slow(u64 subnet_prefix, u16 pkey_num, u32 *sid) +{ + int ret; + struct sel_ib_pkey *pkey; + struct sel_ib_pkey *new = NULL; + unsigned long flags; + + spin_lock_irqsave(&sel_ib_pkey_lock, flags); + pkey = sel_ib_pkey_find(subnet_prefix, pkey_num); + if (pkey) { + *sid = pkey->psec.sid; + spin_unlock_irqrestore(&sel_ib_pkey_lock, flags); + return 0; + } + + ret = security_ib_pkey_sid(&selinux_state, subnet_prefix, pkey_num, + sid); + if (ret) + goto out; + + /* If this memory allocation fails still return 0. The SID + * is valid, it just won't be added to the cache. + */ + new = kzalloc(sizeof(*new), GFP_ATOMIC); + if (!new) { + ret = -ENOMEM; + goto out; + } + + new->psec.subnet_prefix = subnet_prefix; + new->psec.pkey = pkey_num; + new->psec.sid = *sid; + sel_ib_pkey_insert(new); + +out: + spin_unlock_irqrestore(&sel_ib_pkey_lock, flags); + return ret; +} + +/** + * sel_ib_pkey_sid - Lookup the SID of a PKEY + * @subnet_prefix: subnet_prefix + * @pkey_num: pkey number + * @sid: pkey SID + * + * Description: + * This function determines the SID of a PKEY using the fastest method + * possible. First the pkey table is queried, but if an entry can't be found + * then the policy is queried and the result is added to the table to speedup + * future queries. Returns zero on success, negative values on failure. + * + */ +int sel_ib_pkey_sid(u64 subnet_prefix, u16 pkey_num, u32 *sid) +{ + struct sel_ib_pkey *pkey; + + rcu_read_lock(); + pkey = sel_ib_pkey_find(subnet_prefix, pkey_num); + if (pkey) { + *sid = pkey->psec.sid; + rcu_read_unlock(); + return 0; + } + rcu_read_unlock(); + + return sel_ib_pkey_sid_slow(subnet_prefix, pkey_num, sid); +} + +/** + * sel_ib_pkey_flush - Flush the entire pkey table + * + * Description: + * Remove all entries from the pkey table + * + */ +void sel_ib_pkey_flush(void) +{ + unsigned int idx; + struct sel_ib_pkey *pkey, *pkey_tmp; + unsigned long flags; + + spin_lock_irqsave(&sel_ib_pkey_lock, flags); + for (idx = 0; idx < SEL_PKEY_HASH_SIZE; idx++) { + list_for_each_entry_safe(pkey, pkey_tmp, + &sel_ib_pkey_hash[idx].list, list) { + list_del_rcu(&pkey->list); + kfree_rcu(pkey, rcu); + } + sel_ib_pkey_hash[idx].size = 0; + } + spin_unlock_irqrestore(&sel_ib_pkey_lock, flags); +} + +static __init int sel_ib_pkey_init(void) +{ + int iter; + + if (!selinux_enabled_boot) + return 0; + + for (iter = 0; iter < SEL_PKEY_HASH_SIZE; iter++) { + INIT_LIST_HEAD(&sel_ib_pkey_hash[iter].list); + sel_ib_pkey_hash[iter].size = 0; + } + + return 0; +} + +subsys_initcall(sel_ib_pkey_init); |