/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Implementation of the access vector table type.
 *
 * Author : Stephen Smalley, <stephen.smalley.work@gmail.com>
 */

/* Updated: Frank Mayer <mayerf@tresys.com> and
 *          Karl MacMillan <kmacmillan@tresys.com>
 *          Added conditional policy language extensions
 *          Copyright (C) 2003 Tresys Technology, LLC
 *
 * Updated: Yuichi Nakamura <ynakam@hitachisoft.jp>
 *          Tuned number of hash slots for avtab to reduce memory usage
 */

#include <linux/bitops.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include "avtab.h"
#include "policydb.h"
#include "hash.h"

static struct kmem_cache *avtab_node_cachep __ro_after_init;
static struct kmem_cache *avtab_xperms_cachep __ro_after_init;

static inline u32 avtab_hash(const struct avtab_key *keyp, u32 mask)
{
        return av_hash((u32)keyp->target_class, (u32)keyp->target_type,
                       (u32)keyp->source_type, mask);
}

static struct avtab_node *avtab_insert_node(struct avtab *h,
                                            struct avtab_node **dst,
                                            const struct avtab_key *key,
                                            const struct avtab_datum *datum)
{
        struct avtab_node *newnode;
        struct avtab_extended_perms *xperms;
        newnode = kmem_cache_zalloc(avtab_node_cachep, GFP_KERNEL);
        if (newnode == NULL)
                return NULL;
        newnode->key = *key;

        if (key->specified & AVTAB_XPERMS) {
                xperms = kmem_cache_zalloc(avtab_xperms_cachep, GFP_KERNEL);
                if (xperms == NULL) {
                        kmem_cache_free(avtab_node_cachep, newnode);
                        return NULL;
                }
                *xperms = *(datum->u.xperms);
                newnode->datum.u.xperms = xperms;
        } else {
                newnode->datum.u.data = datum->u.data;
        }

        newnode->next = *dst;
        *dst = newnode;

        h->nel++;
        return newnode;
}

static int avtab_node_cmp(const struct avtab_key *key1,
                          const struct avtab_key *key2)
{
        u16 specified = key1->specified & ~(AVTAB_ENABLED | AVTAB_ENABLED_OLD);

        if (key1->source_type == key2->source_type &&
            key1->target_type == key2->target_type &&
            key1->target_class == key2->target_class &&
            (specified & key2->specified))
                return 0;
        if (key1->source_type < key2->source_type)
                return -1;
        if (key1->source_type == key2->source_type &&
            key1->target_type < key2->target_type)
                return -1;
        if (key1->source_type == key2->source_type &&
            key1->target_type == key2->target_type &&
            key1->target_class < key2->target_class)
                return -1;
        return 1;
}

static int avtab_insert(struct avtab *h, const struct avtab_key *key,
                        const struct avtab_datum *datum)
{
        u32 hvalue;
        struct avtab_node *prev, *cur, *newnode;
        int cmp;

        if (!h || !h->nslot || h->nel == U32_MAX)
                return -EINVAL;

        hvalue = avtab_hash(key, h->mask);
        for (prev = NULL, cur = h->htable[hvalue]; cur;
             prev = cur, cur = cur->next) {
                cmp = avtab_node_cmp(key, &cur->key);
                /* extended perms may not be unique */
                if (cmp == 0 && !(key->specified & AVTAB_XPERMS))
                        return -EEXIST;
                if (cmp <= 0)
                        break;
        }

        newnode = avtab_insert_node(h, prev ? &prev->next : &h->htable[hvalue],
                                    key, datum);
        if (!newnode)
                return -ENOMEM;

        return 0;
}

/* Unlike avtab_insert(), this function allow multiple insertions of the same
 * key/specified mask into the table, as needed by the conditional avtab.
 * It also returns a pointer to the node inserted.
 */
struct avtab_node *avtab_insert_nonunique(struct avtab *h,
                                          const struct avtab_key *key,
                                          const struct avtab_datum *datum)
{
        u32 hvalue;
        struct avtab_node *prev, *cur;
        int cmp;

        if (!h || !h->nslot || h->nel == U32_MAX)
                return NULL;
        hvalue = avtab_hash(key, h->mask);
        for (prev = NULL, cur = h->htable[hvalue]; cur;
             prev = cur, cur = cur->next) {
                cmp = avtab_node_cmp(key, &cur->key);
                if (cmp <= 0)
                        break;
        }
        return avtab_insert_node(h, prev ? &prev->next : &h->htable[hvalue],
                                 key, datum);
}

/* This search function returns a node pointer, and can be used in
 * conjunction with avtab_search_next_node()
 */
struct avtab_node *avtab_search_node(struct avtab *h,
                                     const struct avtab_key *key)
{
        u32 hvalue;
        struct avtab_node *cur;
        int cmp;

        if (!h || !h->nslot)
                return NULL;

        hvalue = avtab_hash(key, h->mask);
        for (cur = h->htable[hvalue]; cur; cur = cur->next) {
                cmp = avtab_node_cmp(key, &cur->key);
                if (cmp == 0)
                        return cur;
                if (cmp < 0)
                        break;
        }
        return NULL;
}

struct avtab_node *avtab_search_node_next(struct avtab_node *node,
                                          u16 specified)
{
        struct avtab_key tmp_key;
        struct avtab_node *cur;
        int cmp;

        if (!node)
                return NULL;
        tmp_key = node->key;
        tmp_key.specified = specified;
        for (cur = node->next; cur; cur = cur->next) {
                cmp = avtab_node_cmp(&tmp_key, &cur->key);
                if (cmp == 0)
                        return cur;
                if (cmp < 0)
                        break;
        }
        return NULL;
}

void avtab_destroy(struct avtab *h)
{
        u32 i;
        struct avtab_node *cur, *temp;

        if (!h)
                return;

        for (i = 0; i < h->nslot; i++) {
                cur = h->htable[i];
                while (cur) {
                        temp = cur;
                        cur = cur->next;
                        if (temp->key.specified & AVTAB_XPERMS)
                                kmem_cache_free(avtab_xperms_cachep,
                                                temp->datum.u.xperms);
                        kmem_cache_free(avtab_node_cachep, temp);
                }
        }
        kvfree(h->htable);
        h->htable = NULL;
        h->nel = 0;
        h->nslot = 0;
        h->mask = 0;
}

void avtab_init(struct avtab *h)
{
        h->htable = NULL;
        h->nel = 0;
        h->nslot = 0;
        h->mask = 0;
}

static int avtab_alloc_common(struct avtab *h, u32 nslot)
{
        if (!nslot)
                return 0;

        h->htable = kvcalloc(nslot, sizeof(void *), GFP_KERNEL);
        if (!h->htable)
                return -ENOMEM;

        h->nslot = nslot;
        h->mask = nslot - 1;
        return 0;
}

int avtab_alloc(struct avtab *h, u32 nrules)
{
        int rc;
        u32 nslot = 0;

        if (nrules != 0) {
                nslot = nrules > 3 ? rounddown_pow_of_two(nrules / 2) : 2;
                if (nslot > MAX_AVTAB_HASH_BUCKETS)
                        nslot = MAX_AVTAB_HASH_BUCKETS;

                rc = avtab_alloc_common(h, nslot);
                if (rc)
                        return rc;
        }

        pr_debug("SELinux: %d avtab hash slots, %d rules.\n", nslot, nrules);
        return 0;
}

int avtab_alloc_dup(struct avtab *new, const struct avtab *orig)
{
        return avtab_alloc_common(new, orig->nslot);
}

#ifdef CONFIG_SECURITY_SELINUX_DEBUG
void avtab_hash_eval(struct avtab *h, const char *tag)
{
        u32 i, chain_len, slots_used, max_chain_len;
        unsigned long long chain2_len_sum;
        struct avtab_node *cur;

        slots_used = 0;
        max_chain_len = 0;
        chain2_len_sum = 0;
        for (i = 0; i < h->nslot; i++) {
                cur = h->htable[i];
                if (cur) {
                        slots_used++;
                        chain_len = 0;
                        while (cur) {
                                chain_len++;
                                cur = cur->next;
                        }

                        if (chain_len > max_chain_len)
                                max_chain_len = chain_len;
                        chain2_len_sum +=
                                (unsigned long long)chain_len * chain_len;
                }
        }

        pr_debug("SELinux: %s:  %d entries and %d/%d buckets used, "
                 "longest chain length %d, sum of chain length^2 %llu\n",
                 tag, h->nel, slots_used, h->nslot, max_chain_len,
                 chain2_len_sum);
}
#endif /* CONFIG_SECURITY_SELINUX_DEBUG */

/* clang-format off */
static const uint16_t spec_order[] = {
        AVTAB_ALLOWED,
        AVTAB_AUDITDENY,
        AVTAB_AUDITALLOW,
        AVTAB_TRANSITION,
        AVTAB_CHANGE,
        AVTAB_MEMBER,
        AVTAB_XPERMS_ALLOWED,
        AVTAB_XPERMS_AUDITALLOW,
        AVTAB_XPERMS_DONTAUDIT
};
/* clang-format on */

int avtab_read_item(struct avtab *a, struct policy_file *fp, struct policydb *pol,
                    int (*insertf)(struct avtab *a, const struct avtab_key *k,
                                   const struct avtab_datum *d, void *p),
                    void *p, bool conditional)
{
        __le16 buf16[4];
        u16 enabled;
        u32 items, items2, val, i;
        struct avtab_key key;
        struct avtab_datum datum;
        struct avtab_extended_perms xperms;
        __le32 buf32[ARRAY_SIZE(xperms.perms.p)];
        int rc;
        unsigned int set, vers = pol->policyvers;

        memset(&key, 0, sizeof(struct avtab_key));
        memset(&datum, 0, sizeof(struct avtab_datum));

        if (vers < POLICYDB_VERSION_AVTAB) {
                rc = next_entry(buf32, fp, sizeof(u32));
                if (rc) {
                        pr_err("SELinux: avtab: truncated entry\n");
                        return rc;
                }
                items2 = le32_to_cpu(buf32[0]);
                if (items2 > ARRAY_SIZE(buf32)) {
                        pr_err("SELinux: avtab: entry overflow\n");
                        return -EINVAL;
                }
                rc = next_entry(buf32, fp, sizeof(u32) * items2);
                if (rc) {
                        pr_err("SELinux: avtab: truncated entry\n");
                        return rc;
                }
                items = 0;

                val = le32_to_cpu(buf32[items++]);
                key.source_type = (u16)val;
                if (key.source_type != val) {
                        pr_err("SELinux: avtab: truncated source type\n");
                        return -EINVAL;
                }
                val = le32_to_cpu(buf32[items++]);
                key.target_type = (u16)val;
                if (key.target_type != val) {
                        pr_err("SELinux: avtab: truncated target type\n");
                        return -EINVAL;
                }
                val = le32_to_cpu(buf32[items++]);
                key.target_class = (u16)val;
                if (key.target_class != val) {
                        pr_err("SELinux: avtab: truncated target class\n");
                        return -EINVAL;
                }

                val = le32_to_cpu(buf32[items++]);
                enabled = (val & AVTAB_ENABLED_OLD) ? AVTAB_ENABLED : 0;

                if (!(val & (AVTAB_AV | AVTAB_TYPE))) {
                        pr_err("SELinux: avtab: null entry\n");
                        return -EINVAL;
                }
                if ((val & AVTAB_AV) && (val & AVTAB_TYPE)) {
                        pr_err("SELinux: avtab: entry has both access vectors and types\n");
                        return -EINVAL;
                }
                if (val & AVTAB_XPERMS) {
                        pr_err("SELinux: avtab: entry has extended permissions\n");
                        return -EINVAL;
                }

                for (i = 0; i < ARRAY_SIZE(spec_order); i++) {
                        if (val & spec_order[i]) {
                                key.specified = spec_order[i] | enabled;
                                datum.u.data = le32_to_cpu(buf32[items++]);
                                rc = insertf(a, &key, &datum, p);
                                if (rc)
                                        return rc;
                        }
                }

                if (items != items2) {
                        pr_err("SELinux: avtab: entry only had %d items, expected %d\n",
                               items2, items);
                        return -EINVAL;
                }
                return 0;
        }

        rc = next_entry(buf16, fp, sizeof(u16) * 4);
        if (rc) {
                pr_err("SELinux: avtab: truncated entry\n");
                return rc;
        }

        items = 0;
        key.source_type = le16_to_cpu(buf16[items++]);
        key.target_type = le16_to_cpu(buf16[items++]);
        key.target_class = le16_to_cpu(buf16[items++]);
        key.specified = le16_to_cpu(buf16[items++]);

        if (!policydb_type_isvalid(pol, key.source_type) ||
            !policydb_type_isvalid(pol, key.target_type) ||
            !policydb_class_isvalid(pol, key.target_class)) {
                pr_err("SELinux: avtab: invalid type or class\n");
                return -EINVAL;
        }

        set = hweight16(key.specified & (AVTAB_XPERMS | AVTAB_TYPE | AVTAB_AV));
        if (!set || set > 1) {
                pr_err("SELinux:  avtab:  more than one specifier\n");
                return -EINVAL;
        }

        if ((vers < POLICYDB_VERSION_XPERMS_IOCTL) &&
            (key.specified & AVTAB_XPERMS)) {
                pr_err("SELinux:  avtab:  policy version %u does not "
                       "support extended permissions rules and one "
                       "was specified\n",
                       vers);
                return -EINVAL;
        } else if ((vers < POLICYDB_VERSION_COND_XPERMS) &&
                   (key.specified & AVTAB_XPERMS) && conditional) {
                pr_err("SELinux:  avtab:  policy version %u does not "
                       "support extended permissions rules in conditional "
                       "policies and one was specified\n",
                       vers);
                return -EINVAL;
        } else if (key.specified & AVTAB_XPERMS) {
                memset(&xperms, 0, sizeof(struct avtab_extended_perms));
                rc = next_entry(&xperms.specified, fp, sizeof(u8));
                if (rc) {
                        pr_err("SELinux: avtab: truncated entry\n");
                        return rc;
                }
                rc = next_entry(&xperms.driver, fp, sizeof(u8));
                if (rc) {
                        pr_err("SELinux: avtab: truncated entry\n");
                        return rc;
                }
                rc = next_entry(buf32, fp,
                                sizeof(u32) * ARRAY_SIZE(xperms.perms.p));
                if (rc) {
                        pr_err("SELinux: avtab: truncated entry\n");
                        return rc;
                }
                for (i = 0; i < ARRAY_SIZE(xperms.perms.p); i++)
                        xperms.perms.p[i] = le32_to_cpu(buf32[i]);
                datum.u.xperms = &xperms;
        } else {
                rc = next_entry(buf32, fp, sizeof(u32));
                if (rc) {
                        pr_err("SELinux: avtab: truncated entry\n");
                        return rc;
                }
                datum.u.data = le32_to_cpu(*buf32);
        }
        if ((key.specified & AVTAB_TYPE) &&
            !policydb_type_isvalid(pol, datum.u.data)) {
                pr_err("SELinux: avtab: invalid type\n");
                return -EINVAL;
        }
        return insertf(a, &key, &datum, p);
}

static int avtab_insertf(struct avtab *a, const struct avtab_key *k,
                         const struct avtab_datum *d, void *p)
{
        return avtab_insert(a, k, d);
}

int avtab_read(struct avtab *a, struct policy_file *fp, struct policydb *pol)
{
        int rc;
        __le32 buf[1];
        u32 nel, i;

        rc = next_entry(buf, fp, sizeof(u32));
        if (rc < 0) {
                pr_err("SELinux: avtab: truncated table\n");
                goto bad;
        }
        nel = le32_to_cpu(buf[0]);
        if (!nel) {
                pr_err("SELinux: avtab: table is empty\n");
                rc = -EINVAL;
                goto bad;
        }

        rc = avtab_alloc(a, nel);
        if (rc)
                goto bad;

        for (i = 0; i < nel; i++) {
                rc = avtab_read_item(a, fp, pol, avtab_insertf, NULL, false);
                if (rc) {
                        if (rc == -ENOMEM)
                                pr_err("SELinux: avtab: out of memory\n");
                        else if (rc == -EEXIST)
                                pr_err("SELinux: avtab: duplicate entry\n");

                        goto bad;
                }
        }

        rc = 0;
out:
        return rc;

bad:
        avtab_destroy(a);
        goto out;
}

int avtab_write_item(struct policydb *p, const struct avtab_node *cur, struct policy_file *fp)
{
        __le16 buf16[4];
        __le32 buf32[ARRAY_SIZE(cur->datum.u.xperms->perms.p)];
        int rc;
        unsigned int i;

        buf16[0] = cpu_to_le16(cur->key.source_type);
        buf16[1] = cpu_to_le16(cur->key.target_type);
        buf16[2] = cpu_to_le16(cur->key.target_class);
        buf16[3] = cpu_to_le16(cur->key.specified);
        rc = put_entry(buf16, sizeof(u16), 4, fp);
        if (rc)
                return rc;

        if (cur->key.specified & AVTAB_XPERMS) {
                rc = put_entry(&cur->datum.u.xperms->specified, sizeof(u8), 1,
                               fp);
                if (rc)
                        return rc;
                rc = put_entry(&cur->datum.u.xperms->driver, sizeof(u8), 1, fp);
                if (rc)
                        return rc;
                for (i = 0; i < ARRAY_SIZE(cur->datum.u.xperms->perms.p); i++)
                        buf32[i] = cpu_to_le32(cur->datum.u.xperms->perms.p[i]);
                rc = put_entry(buf32, sizeof(u32),
                               ARRAY_SIZE(cur->datum.u.xperms->perms.p), fp);
        } else {
                buf32[0] = cpu_to_le32(cur->datum.u.data);
                rc = put_entry(buf32, sizeof(u32), 1, fp);
        }
        if (rc)
                return rc;
        return 0;
}

int avtab_write(struct policydb *p, struct avtab *a, struct policy_file *fp)
{
        u32 i;
        int rc = 0;
        struct avtab_node *cur;
        __le32 buf[1];

        buf[0] = cpu_to_le32(a->nel);
        rc = put_entry(buf, sizeof(u32), 1, fp);
        if (rc)
                return rc;

        for (i = 0; i < a->nslot; i++) {
                for (cur = a->htable[i]; cur; cur = cur->next) {
                        rc = avtab_write_item(p, cur, fp);
                        if (rc)
                                return rc;
                }
        }

        return rc;
}

void __init avtab_cache_init(void)
{
        avtab_node_cachep = KMEM_CACHE(avtab_node, SLAB_PANIC);
        avtab_xperms_cachep = KMEM_CACHE(avtab_extended_perms, SLAB_PANIC);
}