diff options
Diffstat (limited to 'security/selinux/ss/sidtab.h')
| -rw-r--r-- | security/selinux/ss/sidtab.h | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/security/selinux/ss/sidtab.h b/security/selinux/ss/sidtab.h new file mode 100644 index 000000000..9fce0d553 --- /dev/null +++ b/security/selinux/ss/sidtab.h @@ -0,0 +1,159 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * A security identifier table (sidtab) is a lookup table + * of security context structures indexed by SID value. + * + * Original author: Stephen Smalley, <sds@tycho.nsa.gov> + * Author: Ondrej Mosnacek, <omosnacek@gmail.com> + * + * Copyright (C) 2018 Red Hat, Inc. + */ +#ifndef _SS_SIDTAB_H_ +#define _SS_SIDTAB_H_ + +#include <linux/spinlock_types.h> +#include <linux/log2.h> +#include <linux/hashtable.h> + +#include "context.h" + +struct sidtab_entry { + u32 sid; + u32 hash; + struct context context; +#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0 + struct sidtab_str_cache __rcu *cache; +#endif + struct hlist_node list; +}; + +union sidtab_entry_inner { + struct sidtab_node_inner *ptr_inner; + struct sidtab_node_leaf *ptr_leaf; +}; + +/* align node size to page boundary */ +#define SIDTAB_NODE_ALLOC_SHIFT PAGE_SHIFT +#define SIDTAB_NODE_ALLOC_SIZE PAGE_SIZE + +#define size_to_shift(size) ((size) == 1 ? 1 : (const_ilog2((size) - 1) + 1)) + +#define SIDTAB_INNER_SHIFT \ + (SIDTAB_NODE_ALLOC_SHIFT - size_to_shift(sizeof(union sidtab_entry_inner))) +#define SIDTAB_INNER_ENTRIES ((size_t)1 << SIDTAB_INNER_SHIFT) +#define SIDTAB_LEAF_ENTRIES \ + (SIDTAB_NODE_ALLOC_SIZE / sizeof(struct sidtab_entry)) + +#define SIDTAB_MAX_BITS 32 +#define SIDTAB_MAX U32_MAX +/* ensure enough tree levels for SIDTAB_MAX entries */ +#define SIDTAB_MAX_LEVEL \ + DIV_ROUND_UP(SIDTAB_MAX_BITS - size_to_shift(SIDTAB_LEAF_ENTRIES), \ + SIDTAB_INNER_SHIFT) + +struct sidtab_node_leaf { + struct sidtab_entry entries[SIDTAB_LEAF_ENTRIES]; +}; + +struct sidtab_node_inner { + union sidtab_entry_inner entries[SIDTAB_INNER_ENTRIES]; +}; + +struct sidtab_isid_entry { + int set; + struct sidtab_entry entry; +}; + +struct sidtab_convert_params { + int (*func)(struct context *oldc, struct context *newc, void *args, gfp_t gfp_flags); + void *args; + struct sidtab *target; +}; + +#define SIDTAB_HASH_BITS CONFIG_SECURITY_SELINUX_SIDTAB_HASH_BITS +#define SIDTAB_HASH_BUCKETS (1 << SIDTAB_HASH_BITS) + +struct sidtab { + /* + * lock-free read access only for as many items as a prior read of + * 'count' + */ + union sidtab_entry_inner roots[SIDTAB_MAX_LEVEL + 1]; + /* + * access atomically via {READ|WRITE}_ONCE(); only increment under + * spinlock + */ + u32 count; + /* access only under spinlock */ + struct sidtab_convert_params *convert; + bool frozen; + spinlock_t lock; + +#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0 + /* SID -> context string cache */ + u32 cache_free_slots; + struct list_head cache_lru_list; + spinlock_t cache_lock; +#endif + + /* index == SID - 1 (no entry for SECSID_NULL) */ + struct sidtab_isid_entry isids[SECINITSID_NUM]; + + /* Hash table for fast reverse context-to-sid lookups. */ + DECLARE_HASHTABLE(context_to_sid, SIDTAB_HASH_BITS); +}; + +int sidtab_init(struct sidtab *s); +int sidtab_set_initial(struct sidtab *s, u32 sid, struct context *context); +struct sidtab_entry *sidtab_search_entry(struct sidtab *s, u32 sid); +struct sidtab_entry *sidtab_search_entry_force(struct sidtab *s, u32 sid); + +static inline struct context *sidtab_search(struct sidtab *s, u32 sid) +{ + struct sidtab_entry *entry = sidtab_search_entry(s, sid); + + return entry ? &entry->context : NULL; +} + +static inline struct context *sidtab_search_force(struct sidtab *s, u32 sid) +{ + struct sidtab_entry *entry = sidtab_search_entry_force(s, sid); + + return entry ? &entry->context : NULL; +} + +int sidtab_convert(struct sidtab *s, struct sidtab_convert_params *params); + +void sidtab_cancel_convert(struct sidtab *s); + +void sidtab_freeze_begin(struct sidtab *s, unsigned long *flags) __acquires(&s->lock); +void sidtab_freeze_end(struct sidtab *s, unsigned long *flags) __releases(&s->lock); + +int sidtab_context_to_sid(struct sidtab *s, struct context *context, u32 *sid); + +void sidtab_destroy(struct sidtab *s); + +int sidtab_hash_stats(struct sidtab *sidtab, char *page); + +#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); +int sidtab_sid2str_get(struct sidtab *s, struct sidtab_entry *entry, + char **out, u32 *out_len); +#else +static inline void sidtab_sid2str_put(struct sidtab *s, + struct sidtab_entry *entry, + const char *str, u32 str_len) +{ +} +static inline int sidtab_sid2str_get(struct sidtab *s, + struct sidtab_entry *entry, + char **out, u32 *out_len) +{ + return -ENOENT; +} +#endif /* CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0 */ + +#endif /* _SS_SIDTAB_H_ */ + + |