diff options
author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
---|---|---|
committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
commit | 2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch) | |
tree | 848558de17fb3008cdf4d861b01ac7781903ce39 /security/selinux/ss/sidtab.c | |
parent | Initial commit. (diff) | |
download | linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip |
Adding upstream version 6.1.76.upstream/6.1.76upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | security/selinux/ss/sidtab.c | 628 |
1 files changed, 628 insertions, 0 deletions
diff --git a/security/selinux/ss/sidtab.c b/security/selinux/ss/sidtab.c new file mode 100644 index 000000000..db5cce385 --- /dev/null +++ b/security/selinux/ss/sidtab.c @@ -0,0 +1,628 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Implementation of the SID table type. + * + * Original author: Stephen Smalley, <sds@tycho.nsa.gov> + * Author: Ondrej Mosnacek, <omosnacek@gmail.com> + * + * Copyright (C) 2018 Red Hat, Inc. + */ +#include <linux/errno.h> +#include <linux/kernel.h> +#include <linux/list.h> +#include <linux/rcupdate.h> +#include <linux/slab.h> +#include <linux/sched.h> +#include <linux/spinlock.h> +#include <asm/barrier.h> +#include "flask.h" +#include "security.h" +#include "sidtab.h" + +struct sidtab_str_cache { + struct rcu_head rcu_member; + struct list_head lru_member; + struct sidtab_entry *parent; + u32 len; + char str[]; +}; + +#define index_to_sid(index) ((index) + SECINITSID_NUM + 1) +#define sid_to_index(sid) ((sid) - (SECINITSID_NUM + 1)) + +int sidtab_init(struct sidtab *s) +{ + u32 i; + + memset(s->roots, 0, sizeof(s->roots)); + + for (i = 0; i < SECINITSID_NUM; i++) + s->isids[i].set = 0; + + s->frozen = false; + s->count = 0; + s->convert = NULL; + hash_init(s->context_to_sid); + + spin_lock_init(&s->lock); + +#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0 + s->cache_free_slots = CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE; + INIT_LIST_HEAD(&s->cache_lru_list); + spin_lock_init(&s->cache_lock); +#endif + + return 0; +} + +static u32 context_to_sid(struct sidtab *s, struct context *context, u32 hash) +{ + struct sidtab_entry *entry; + u32 sid = 0; + + rcu_read_lock(); + hash_for_each_possible_rcu(s->context_to_sid, entry, list, hash) { + if (entry->hash != hash) + continue; + if (context_cmp(&entry->context, context)) { + sid = entry->sid; + break; + } + } + rcu_read_unlock(); + return sid; +} + +int sidtab_set_initial(struct sidtab *s, u32 sid, struct context *context) +{ + struct sidtab_isid_entry *isid; + u32 hash; + int rc; + + if (sid == 0 || sid > SECINITSID_NUM) + return -EINVAL; + + isid = &s->isids[sid - 1]; + + rc = context_cpy(&isid->entry.context, context); + if (rc) + return rc; + +#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0 + isid->entry.cache = NULL; +#endif + isid->set = 1; + + hash = context_compute_hash(context); + + /* + * Multiple initial sids may map to the same context. Check that this + * context is not already represented in the context_to_sid hashtable + * to avoid duplicate entries and long linked lists upon hash + * collision. + */ + if (!context_to_sid(s, context, hash)) { + isid->entry.sid = sid; + isid->entry.hash = hash; + hash_add(s->context_to_sid, &isid->entry.list, hash); + } + + return 0; +} + +int sidtab_hash_stats(struct sidtab *sidtab, char *page) +{ + int i; + int chain_len = 0; + int slots_used = 0; + int entries = 0; + int max_chain_len = 0; + int cur_bucket = 0; + struct sidtab_entry *entry; + + rcu_read_lock(); + hash_for_each_rcu(sidtab->context_to_sid, i, entry, list) { + entries++; + if (i == cur_bucket) { + chain_len++; + if (chain_len == 1) + slots_used++; + } else { + cur_bucket = i; + if (chain_len > max_chain_len) + max_chain_len = chain_len; + chain_len = 0; + } + } + rcu_read_unlock(); + + if (chain_len > max_chain_len) + max_chain_len = chain_len; + + return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n" + "longest chain: %d\n", entries, + slots_used, SIDTAB_HASH_BUCKETS, max_chain_len); +} + +static u32 sidtab_level_from_count(u32 count) +{ + u32 capacity = SIDTAB_LEAF_ENTRIES; + u32 level = 0; + + while (count > capacity) { + capacity <<= SIDTAB_INNER_SHIFT; + ++level; + } + return level; +} + +static int sidtab_alloc_roots(struct sidtab *s, u32 level) +{ + u32 l; + + if (!s->roots[0].ptr_leaf) { + s->roots[0].ptr_leaf = kzalloc(SIDTAB_NODE_ALLOC_SIZE, + GFP_ATOMIC); + if (!s->roots[0].ptr_leaf) + return -ENOMEM; + } + for (l = 1; l <= level; ++l) + if (!s->roots[l].ptr_inner) { + s->roots[l].ptr_inner = kzalloc(SIDTAB_NODE_ALLOC_SIZE, + GFP_ATOMIC); + if (!s->roots[l].ptr_inner) + return -ENOMEM; + s->roots[l].ptr_inner->entries[0] = s->roots[l - 1]; + } + return 0; +} + +static struct sidtab_entry *sidtab_do_lookup(struct sidtab *s, u32 index, + int alloc) +{ + union sidtab_entry_inner *entry; + u32 level, capacity_shift, leaf_index = index / SIDTAB_LEAF_ENTRIES; + + /* find the level of the subtree we need */ + level = sidtab_level_from_count(index + 1); + capacity_shift = level * SIDTAB_INNER_SHIFT; + + /* allocate roots if needed */ + if (alloc && sidtab_alloc_roots(s, level) != 0) + return NULL; + + /* lookup inside the subtree */ + entry = &s->roots[level]; + while (level != 0) { + capacity_shift -= SIDTAB_INNER_SHIFT; + --level; + + entry = &entry->ptr_inner->entries[leaf_index >> capacity_shift]; + leaf_index &= ((u32)1 << capacity_shift) - 1; + + if (!entry->ptr_inner) { + if (alloc) + entry->ptr_inner = kzalloc(SIDTAB_NODE_ALLOC_SIZE, + GFP_ATOMIC); + if (!entry->ptr_inner) + return NULL; + } + } + if (!entry->ptr_leaf) { + if (alloc) + entry->ptr_leaf = kzalloc(SIDTAB_NODE_ALLOC_SIZE, + GFP_ATOMIC); + if (!entry->ptr_leaf) + return NULL; + } + return &entry->ptr_leaf->entries[index % SIDTAB_LEAF_ENTRIES]; +} + +static struct sidtab_entry *sidtab_lookup(struct sidtab *s, u32 index) +{ + /* read entries only after reading count */ + u32 count = smp_load_acquire(&s->count); + + if (index >= count) + return NULL; + + return sidtab_do_lookup(s, index, 0); +} + +static struct sidtab_entry *sidtab_lookup_initial(struct sidtab *s, u32 sid) +{ + return s->isids[sid - 1].set ? &s->isids[sid - 1].entry : NULL; +} + +static struct sidtab_entry *sidtab_search_core(struct sidtab *s, u32 sid, + int force) +{ + if (sid != 0) { + struct sidtab_entry *entry; + + if (sid > SECINITSID_NUM) + entry = sidtab_lookup(s, sid_to_index(sid)); + else + entry = sidtab_lookup_initial(s, sid); + if (entry && (!entry->context.len || force)) + return entry; + } + + return sidtab_lookup_initial(s, SECINITSID_UNLABELED); +} + +struct sidtab_entry *sidtab_search_entry(struct sidtab *s, u32 sid) +{ + return sidtab_search_core(s, sid, 0); +} + +struct sidtab_entry *sidtab_search_entry_force(struct sidtab *s, u32 sid) +{ + return sidtab_search_core(s, sid, 1); +} + +int sidtab_context_to_sid(struct sidtab *s, struct context *context, + u32 *sid) +{ + unsigned long flags; + u32 count, hash = context_compute_hash(context); + struct sidtab_convert_params *convert; + struct sidtab_entry *dst, *dst_convert; + int rc; + + *sid = context_to_sid(s, context, hash); + if (*sid) + return 0; + + /* lock-free search failed: lock, re-search, and insert if not found */ + spin_lock_irqsave(&s->lock, flags); + + rc = 0; + *sid = context_to_sid(s, context, hash); + if (*sid) + goto out_unlock; + + if (unlikely(s->frozen)) { + /* + * This sidtab is now frozen - tell the caller to abort and + * get the new one. + */ + rc = -ESTALE; + goto out_unlock; + } + + count = s->count; + convert = s->convert; + + /* bail out if we already reached max entries */ + rc = -EOVERFLOW; + if (count >= SIDTAB_MAX) + goto out_unlock; + + /* insert context into new entry */ + rc = -ENOMEM; + dst = sidtab_do_lookup(s, count, 1); + if (!dst) + goto out_unlock; + + dst->sid = index_to_sid(count); + dst->hash = hash; + + rc = context_cpy(&dst->context, context); + if (rc) + goto out_unlock; + + /* + * if we are building a new sidtab, we need to convert the context + * and insert it there as well + */ + if (convert) { + rc = -ENOMEM; + dst_convert = sidtab_do_lookup(convert->target, count, 1); + if (!dst_convert) { + context_destroy(&dst->context); + goto out_unlock; + } + + rc = convert->func(context, &dst_convert->context, + convert->args, GFP_ATOMIC); + if (rc) { + context_destroy(&dst->context); + goto out_unlock; + } + dst_convert->sid = index_to_sid(count); + dst_convert->hash = context_compute_hash(&dst_convert->context); + convert->target->count = count + 1; + + hash_add_rcu(convert->target->context_to_sid, + &dst_convert->list, dst_convert->hash); + } + + if (context->len) + pr_info("SELinux: Context %s is not valid (left unmapped).\n", + context->str); + + *sid = index_to_sid(count); + + /* write entries before updating count */ + smp_store_release(&s->count, count + 1); + hash_add_rcu(s->context_to_sid, &dst->list, dst->hash); + + rc = 0; +out_unlock: + spin_unlock_irqrestore(&s->lock, flags); + return rc; +} + +static void sidtab_convert_hashtable(struct sidtab *s, u32 count) +{ + struct sidtab_entry *entry; + u32 i; + + for (i = 0; i < count; i++) { + entry = sidtab_do_lookup(s, i, 0); + entry->sid = index_to_sid(i); + entry->hash = context_compute_hash(&entry->context); + + hash_add_rcu(s->context_to_sid, &entry->list, entry->hash); + } +} + +static int sidtab_convert_tree(union sidtab_entry_inner *edst, + union sidtab_entry_inner *esrc, + u32 *pos, u32 count, u32 level, + struct sidtab_convert_params *convert) +{ + int rc; + u32 i; + + if (level != 0) { + if (!edst->ptr_inner) { + edst->ptr_inner = kzalloc(SIDTAB_NODE_ALLOC_SIZE, + GFP_KERNEL); + if (!edst->ptr_inner) + return -ENOMEM; + } + i = 0; + while (i < SIDTAB_INNER_ENTRIES && *pos < count) { + rc = sidtab_convert_tree(&edst->ptr_inner->entries[i], + &esrc->ptr_inner->entries[i], + pos, count, level - 1, + convert); + if (rc) + return rc; + i++; + } + } else { + if (!edst->ptr_leaf) { + edst->ptr_leaf = kzalloc(SIDTAB_NODE_ALLOC_SIZE, + GFP_KERNEL); + if (!edst->ptr_leaf) + return -ENOMEM; + } + i = 0; + while (i < SIDTAB_LEAF_ENTRIES && *pos < count) { + rc = convert->func(&esrc->ptr_leaf->entries[i].context, + &edst->ptr_leaf->entries[i].context, + convert->args, GFP_KERNEL); + if (rc) + return rc; + (*pos)++; + i++; + } + cond_resched(); + } + return 0; +} + +int sidtab_convert(struct sidtab *s, struct sidtab_convert_params *params) +{ + unsigned long flags; + u32 count, level, pos; + int rc; + + spin_lock_irqsave(&s->lock, flags); + + /* concurrent policy loads are not allowed */ + if (s->convert) { + spin_unlock_irqrestore(&s->lock, flags); + return -EBUSY; + } + + count = s->count; + level = sidtab_level_from_count(count); + + /* allocate last leaf in the new sidtab (to avoid race with + * live convert) + */ + rc = sidtab_do_lookup(params->target, count - 1, 1) ? 0 : -ENOMEM; + if (rc) { + spin_unlock_irqrestore(&s->lock, flags); + return rc; + } + + /* set count in case no new entries are added during conversion */ + params->target->count = count; + + /* enable live convert of new entries */ + s->convert = params; + + /* we can safely convert the tree outside the lock */ + spin_unlock_irqrestore(&s->lock, flags); + + pr_info("SELinux: Converting %u SID table entries...\n", count); + + /* convert all entries not covered by live convert */ + pos = 0; + rc = sidtab_convert_tree(¶ms->target->roots[level], + &s->roots[level], &pos, count, level, params); + if (rc) { + /* we need to keep the old table - disable live convert */ + spin_lock_irqsave(&s->lock, flags); + s->convert = NULL; + spin_unlock_irqrestore(&s->lock, flags); + return rc; + } + /* + * The hashtable can also be modified in sidtab_context_to_sid() + * so we must re-acquire the lock here. + */ + spin_lock_irqsave(&s->lock, flags); + sidtab_convert_hashtable(params->target, count); + spin_unlock_irqrestore(&s->lock, flags); + + return 0; +} + +void sidtab_cancel_convert(struct sidtab *s) +{ + unsigned long flags; + + /* cancelling policy load - disable live convert of sidtab */ + spin_lock_irqsave(&s->lock, flags); + s->convert = NULL; + spin_unlock_irqrestore(&s->lock, flags); +} + +void sidtab_freeze_begin(struct sidtab *s, unsigned long *flags) __acquires(&s->lock) +{ + spin_lock_irqsave(&s->lock, *flags); + s->frozen = true; + s->convert = NULL; +} +void sidtab_freeze_end(struct sidtab *s, unsigned long *flags) __releases(&s->lock) +{ + spin_unlock_irqrestore(&s->lock, *flags); +} + +static void sidtab_destroy_entry(struct sidtab_entry *entry) +{ + context_destroy(&entry->context); +#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0 + kfree(rcu_dereference_raw(entry->cache)); +#endif +} + +static void sidtab_destroy_tree(union sidtab_entry_inner entry, u32 level) +{ + u32 i; + + if (level != 0) { + struct sidtab_node_inner *node = entry.ptr_inner; + + if (!node) + return; + + for (i = 0; i < SIDTAB_INNER_ENTRIES; i++) + sidtab_destroy_tree(node->entries[i], level - 1); + kfree(node); + } else { + struct sidtab_node_leaf *node = entry.ptr_leaf; + + if (!node) + return; + + for (i = 0; i < SIDTAB_LEAF_ENTRIES; i++) + sidtab_destroy_entry(&node->entries[i]); + kfree(node); + } +} + +void sidtab_destroy(struct sidtab *s) +{ + u32 i, level; + + for (i = 0; i < SECINITSID_NUM; i++) + if (s->isids[i].set) + sidtab_destroy_entry(&s->isids[i].entry); + + level = SIDTAB_MAX_LEVEL; + while (level && !s->roots[level].ptr_inner) + --level; + + sidtab_destroy_tree(s->roots[level], level); + /* + * The context_to_sid hashtable's objects are all shared + * with the isids array and context tree, and so don't need + * to be cleaned up here. + */ +} + +#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0 + +void sidtab_sid2str_put(struct sidtab *s, struct sidtab_entry *entry, + const char *str, u32 str_len) +{ + struct sidtab_str_cache *cache, *victim = NULL; + unsigned long flags; + + /* do not cache invalid contexts */ + if (entry->context.len) + return; + + spin_lock_irqsave(&s->cache_lock, flags); + + cache = rcu_dereference_protected(entry->cache, + lockdep_is_held(&s->cache_lock)); + if (cache) { + /* entry in cache - just bump to the head of LRU list */ + list_move(&cache->lru_member, &s->cache_lru_list); + goto out_unlock; + } + + cache = kmalloc(struct_size(cache, str, str_len), GFP_ATOMIC); + if (!cache) + goto out_unlock; + + if (s->cache_free_slots == 0) { + /* pop a cache entry from the tail and free it */ + victim = container_of(s->cache_lru_list.prev, + struct sidtab_str_cache, lru_member); + list_del(&victim->lru_member); + rcu_assign_pointer(victim->parent->cache, NULL); + } else { + s->cache_free_slots--; + } + cache->parent = entry; + cache->len = str_len; + memcpy(cache->str, str, str_len); + list_add(&cache->lru_member, &s->cache_lru_list); + + rcu_assign_pointer(entry->cache, cache); + +out_unlock: + spin_unlock_irqrestore(&s->cache_lock, flags); + kfree_rcu(victim, rcu_member); +} + +int sidtab_sid2str_get(struct sidtab *s, struct sidtab_entry *entry, + char **out, u32 *out_len) +{ + struct sidtab_str_cache *cache; + int rc = 0; + + if (entry->context.len) + return -ENOENT; /* do not cache invalid contexts */ + + rcu_read_lock(); + + cache = rcu_dereference(entry->cache); + if (!cache) { + rc = -ENOENT; + } else { + *out_len = cache->len; + if (out) { + *out = kmemdup(cache->str, cache->len, GFP_ATOMIC); + if (!*out) + rc = -ENOMEM; + } + } + + rcu_read_unlock(); + + if (!rc && out) + sidtab_sid2str_put(s, entry, *out, *out_len); + return rc; +} + +#endif /* CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0 */ |