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 // SPDX-License-Identifier: GPL-2.0
 /*
  * Implementation of the extensible bitmap type.
  *
  * Author : Stephen Smalley, <sds@tycho.nsa.gov>
  */
 /*
  * Updated: Hewlett-Packard <paul@paul-moore.com>
  *
  *      Added support to import/export the NetLabel category bitmap
  *
  * (c) Copyright Hewlett-Packard Development Company, L.P., 2006
  */
 /*
  * Updated: KaiGai Kohei <kaigai@ak.jp.nec.com>
  *      Applied standard bit operations to improve bitmap scanning.
  */
 
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/errno.h>
 #include <linux/jhash.h>
 #include <net/netlabel.h>
 #include "ebitmap.h"
 #include "policydb.h"
 
 #define BITS_PER_U64    (sizeof(u64) * 8)
 
 static struct kmem_cache *ebitmap_node_cachep __ro_after_init;
 
 int ebitmap_cmp(struct ebitmap *e1, struct ebitmap *e2)
 {
     struct ebitmap_node *n1, *n2;
 
     if (e1->highbit != e2->highbit)
         return 0;
 
     n1 = e1->node;
     n2 = e2->node;
     while (n1 && n2 &&
            (n1->startbit == n2->startbit) &&
            !memcmp(n1->maps, n2->maps, EBITMAP_SIZE / 8)) {
         n1 = n1->next;
         n2 = n2->next;
     }
 
     if (n1 || n2)
         return 0;
 
     return 1;
 }
 
 int ebitmap_cpy(struct ebitmap *dst, struct ebitmap *src)
 {
     struct ebitmap_node *n, *new, *prev;
 
     ebitmap_init(dst);
     n = src->node;
     prev = NULL;
     while (n) {
         new = kmem_cache_zalloc(ebitmap_node_cachep, GFP_ATOMIC);
         if (!new) {
             ebitmap_destroy(dst);
             return -ENOMEM;
         }
         new->startbit = n->startbit;
         memcpy(new->maps, n->maps, EBITMAP_SIZE / 8);
         new->next = NULL;
         if (prev)
             prev->next = new;
         else
             dst->node = new;
         prev = new;
         n = n->next;
     }
 
     dst->highbit = src->highbit;
     return 0;
 }
 
 int ebitmap_and(struct ebitmap *dst, struct ebitmap *e1, struct ebitmap *e2)
 {
     struct ebitmap_node *n;
     int bit, rc;
 
     ebitmap_init(dst);
 
     ebitmap_for_each_positive_bit(e1, n, bit) {
         if (ebitmap_get_bit(e2, bit)) {
             rc = ebitmap_set_bit(dst, bit, 1);
             if (rc < 0)
                 return rc;
         }
     }
     return 0;
 }
 
 
 #ifdef CONFIG_NETLABEL
 /**
  * ebitmap_netlbl_export - Export an ebitmap into a NetLabel category bitmap
  * @ebmap: the ebitmap to export
  * @catmap: the NetLabel category bitmap
  *
  * Description:
  * Export a SELinux extensibile bitmap into a NetLabel category bitmap.
  * Returns zero on success, negative values on error.
  *
  */
 int ebitmap_netlbl_export(struct ebitmap *ebmap,
               struct netlbl_lsm_catmap **catmap)
 {
     struct ebitmap_node *e_iter = ebmap->node;
     unsigned long e_map;
     u32 offset;
     unsigned int iter;
     int rc;
 
     if (e_iter == NULL) {
         *catmap = NULL;
         return 0;
     }
 
     if (*catmap != NULL)
         netlbl_catmap_free(*catmap);
     *catmap = NULL;
 
     while (e_iter) {
         offset = e_iter->startbit;
         for (iter = 0; iter < EBITMAP_UNIT_NUMS; iter++) {
             e_map = e_iter->maps[iter];
             if (e_map != 0) {
                 rc = netlbl_catmap_setlong(catmap,
                                offset,
                                e_map,
                                GFP_ATOMIC);
                 if (rc != 0)
                     goto netlbl_export_failure;
             }
             offset += EBITMAP_UNIT_SIZE;
         }
         e_iter = e_iter->next;
     }
 
     return 0;
 
 netlbl_export_failure:
     netlbl_catmap_free(*catmap);
     return -ENOMEM;
 }
 
 /**
  * ebitmap_netlbl_import - Import a NetLabel category bitmap into an ebitmap
  * @ebmap: the ebitmap to import
  * @catmap: the NetLabel category bitmap
  *
  * Description:
  * Import a NetLabel category bitmap into a SELinux extensibile bitmap.
  * Returns zero on success, negative values on error.
  *
  */
 int ebitmap_netlbl_import(struct ebitmap *ebmap,
               struct netlbl_lsm_catmap *catmap)
 {
     int rc;
     struct ebitmap_node *e_iter = NULL;
     struct ebitmap_node *e_prev = NULL;
     u32 offset = 0, idx;
     unsigned long bitmap;
 
     for (;;) {
         rc = netlbl_catmap_getlong(catmap, &offset, &bitmap);
         if (rc < 0)
             goto netlbl_import_failure;
         if (offset == (u32)-1)
             return 0;
 
         /* don't waste ebitmap space if the netlabel bitmap is empty */
         if (bitmap == 0) {
             offset += EBITMAP_UNIT_SIZE;
             continue;
         }
 
         if (e_iter == NULL ||
             offset >= e_iter->startbit + EBITMAP_SIZE) {
             e_prev = e_iter;
             e_iter = kmem_cache_zalloc(ebitmap_node_cachep, GFP_ATOMIC);
             if (e_iter == NULL)
                 goto netlbl_import_failure;
             e_iter->startbit = offset - (offset % EBITMAP_SIZE);
             if (e_prev == NULL)
                 ebmap->node = e_iter;
             else
                 e_prev->next = e_iter;
             ebmap->highbit = e_iter->startbit + EBITMAP_SIZE;
         }
 
         /* offset will always be aligned to an unsigned long */
         idx = EBITMAP_NODE_INDEX(e_iter, offset);
         e_iter->maps[idx] = bitmap;
 
         /* next */
         offset += EBITMAP_UNIT_SIZE;
     }
 
     /* NOTE: we should never reach this return */
     return 0;
 
 netlbl_import_failure:
     ebitmap_destroy(ebmap);
     return -ENOMEM;
 }
 #endif /* CONFIG_NETLABEL */
 
 /*
  * Check to see if all the bits set in e2 are also set in e1. Optionally,
  * if last_e2bit is non-zero, the highest set bit in e2 cannot exceed
  * last_e2bit.
  */
 int ebitmap_contains(struct ebitmap *e1, struct ebitmap *e2, u32 last_e2bit)
 {
     struct ebitmap_node *n1, *n2;
     int i;
 
     if (e1->highbit < e2->highbit)
         return 0;
 
     n1 = e1->node;
     n2 = e2->node;
 
     while (n1 && n2 && (n1->startbit <= n2->startbit)) {
         if (n1->startbit < n2->startbit) {
             n1 = n1->next;
             continue;
         }
         for (i = EBITMAP_UNIT_NUMS - 1; (i >= 0) && !n2->maps[i]; )
             i--;    /* Skip trailing NULL map entries */
         if (last_e2bit && (i >= 0)) {
             u32 lastsetbit = n2->startbit + i * EBITMAP_UNIT_SIZE +
                      __fls(n2->maps[i]);
             if (lastsetbit > last_e2bit)
                 return 0;
         }
 
         while (i >= 0) {
             if ((n1->maps[i] & n2->maps[i]) != n2->maps[i])
                 return 0;
             i--;
         }
 
         n1 = n1->next;
         n2 = n2->next;
     }
 
     if (n2)
         return 0;
 
     return 1;
 }
 
 int ebitmap_get_bit(struct ebitmap *e, unsigned long bit)
 {
     struct ebitmap_node *n;
 
     if (e->highbit < bit)
         return 0;
 
     n = e->node;
     while (n && (n->startbit <= bit)) {
         if ((n->startbit + EBITMAP_SIZE) > bit)
             return ebitmap_node_get_bit(n, bit);
         n = n->next;
     }
 
     return 0;
 }
 
 int ebitmap_set_bit(struct ebitmap *e, unsigned long bit, int value)
 {
     struct ebitmap_node *n, *prev, *new;
 
     prev = NULL;
     n = e->node;
     while (n && n->startbit <= bit) {
         if ((n->startbit + EBITMAP_SIZE) > bit) {
             if (value) {
                 ebitmap_node_set_bit(n, bit);
             } else {
                 unsigned int s;
 
                 ebitmap_node_clr_bit(n, bit);
 
                 s = find_first_bit(n->maps, EBITMAP_SIZE);
                 if (s < EBITMAP_SIZE)
                     return 0;
 
                 /* drop this node from the bitmap */
                 if (!n->next) {
                     /*
                      * this was the highest map
                      * within the bitmap
                      */
                     if (prev)
                         e->highbit = prev->startbit
                                  + EBITMAP_SIZE;
                     else
                         e->highbit = 0;
                 }
                 if (prev)
                     prev->next = n->next;
                 else
                     e->node = n->next;
                 kmem_cache_free(ebitmap_node_cachep, n);
             }
             return 0;
         }
         prev = n;
         n = n->next;
     }
 
     if (!value)
         return 0;
 
     new = kmem_cache_zalloc(ebitmap_node_cachep, GFP_ATOMIC);
     if (!new)
         return -ENOMEM;
 
     new->startbit = bit - (bit % EBITMAP_SIZE);
     ebitmap_node_set_bit(new, bit);
 
     if (!n)
         /* this node will be the highest map within the bitmap */
         e->highbit = new->startbit + EBITMAP_SIZE;
 
     if (prev) {
         new->next = prev->next;
         prev->next = new;
     } else {
         new->next = e->node;
         e->node = new;
     }
 
     return 0;
 }
 
 void ebitmap_destroy(struct ebitmap *e)
 {
     struct ebitmap_node *n, *temp;
 
     if (!e)
         return;
 
     n = e->node;
     while (n) {
         temp = n;
         n = n->next;
         kmem_cache_free(ebitmap_node_cachep, temp);
     }
 
     e->highbit = 0;
     e->node = NULL;
 }
 
 int ebitmap_read(struct ebitmap *e, void *fp)
 {
     struct ebitmap_node *n = NULL;
     u32 mapunit, count, startbit, index;
     __le32 ebitmap_start;
     u64 map;
     __le64 mapbits;
     __le32 buf[3];
     int rc, i;
 
     ebitmap_init(e);
 
     rc = next_entry(buf, fp, sizeof buf);
     if (rc < 0)
         goto out;
 
     mapunit = le32_to_cpu(buf[0]);
     e->highbit = le32_to_cpu(buf[1]);
     count = le32_to_cpu(buf[2]);
 
     if (mapunit != BITS_PER_U64) {
         pr_err("SELinux: ebitmap: map size %u does not "
                "match my size %zd (high bit was %d)\n",
                mapunit, BITS_PER_U64, e->highbit);
         goto bad;
     }
 
     /* round up e->highbit */
     e->highbit += EBITMAP_SIZE - 1;
     e->highbit -= (e->highbit % EBITMAP_SIZE);
 
     if (!e->highbit) {
         e->node = NULL;
         goto ok;
     }
 
     if (e->highbit && !count)
         goto bad;
 
     for (i = 0; i < count; i++) {
         rc = next_entry(&ebitmap_start, fp, sizeof(u32));
         if (rc < 0) {
             pr_err("SELinux: ebitmap: truncated map\n");
             goto bad;
         }
         startbit = le32_to_cpu(ebitmap_start);
 
         if (startbit & (mapunit - 1)) {
             pr_err("SELinux: ebitmap start bit (%d) is "
                    "not a multiple of the map unit size (%u)\n",
                    startbit, mapunit);
             goto bad;
         }
         if (startbit > e->highbit - mapunit) {
             pr_err("SELinux: ebitmap start bit (%d) is "
                    "beyond the end of the bitmap (%u)\n",
                    startbit, (e->highbit - mapunit));
             goto bad;
         }
 
         if (!n || startbit >= n->startbit + EBITMAP_SIZE) {
             struct ebitmap_node *tmp;
             tmp = kmem_cache_zalloc(ebitmap_node_cachep, GFP_KERNEL);
             if (!tmp) {
                 pr_err("SELinux: ebitmap: out of memory\n");
                 rc = -ENOMEM;
                 goto bad;
             }
             /* round down */
             tmp->startbit = startbit - (startbit % EBITMAP_SIZE);
             if (n)
                 n->next = tmp;
             else
                 e->node = tmp;
             n = tmp;
         } else if (startbit <= n->startbit) {
             pr_err("SELinux: ebitmap: start bit %d"
                    " comes after start bit %d\n",
                    startbit, n->startbit);
             goto bad;
         }
 
         rc = next_entry(&mapbits, fp, sizeof(u64));
         if (rc < 0) {
             pr_err("SELinux: ebitmap: truncated map\n");
             goto bad;
         }
         map = le64_to_cpu(mapbits);
 
         index = (startbit - n->startbit) / EBITMAP_UNIT_SIZE;
         while (map) {
             n->maps[index++] = map & (-1UL);
             map = EBITMAP_SHIFT_UNIT_SIZE(map);
         }
     }
 ok:
     rc = 0;
 out:
     return rc;
 bad:
     if (!rc)
         rc = -EINVAL;
     ebitmap_destroy(e);
     goto out;
 }
 
 int ebitmap_write(struct ebitmap *e, void *fp)
 {
     struct ebitmap_node *n;
     u32 count;
     __le32 buf[3];
     u64 map;
     int bit, last_bit, last_startbit, rc;
 
     buf[0] = cpu_to_le32(BITS_PER_U64);
 
     count = 0;
     last_bit = 0;
     last_startbit = -1;
     ebitmap_for_each_positive_bit(e, n, bit) {
         if (rounddown(bit, (int)BITS_PER_U64) > last_startbit) {
             count++;
             last_startbit = rounddown(bit, BITS_PER_U64);
         }
         last_bit = roundup(bit + 1, BITS_PER_U64);
     }
     buf[1] = cpu_to_le32(last_bit);
     buf[2] = cpu_to_le32(count);
 
     rc = put_entry(buf, sizeof(u32), 3, fp);
     if (rc)
         return rc;
 
     map = 0;
     last_startbit = INT_MIN;
     ebitmap_for_each_positive_bit(e, n, bit) {
         if (rounddown(bit, (int)BITS_PER_U64) > last_startbit) {
             __le64 buf64[1];
 
             /* this is the very first bit */
             if (!map) {
                 last_startbit = rounddown(bit, BITS_PER_U64);
                 map = (u64)1 << (bit - last_startbit);
                 continue;
             }
 
             /* write the last node */
             buf[0] = cpu_to_le32(last_startbit);
             rc = put_entry(buf, sizeof(u32), 1, fp);
             if (rc)
                 return rc;
 
             buf64[0] = cpu_to_le64(map);
             rc = put_entry(buf64, sizeof(u64), 1, fp);
             if (rc)
                 return rc;
 
             /* set up for the next node */
             map = 0;
             last_startbit = rounddown(bit, BITS_PER_U64);
         }
         map |= (u64)1 << (bit - last_startbit);
     }
     /* write the last node */
     if (map) {
         __le64 buf64[1];
 
         /* write the last node */
         buf[0] = cpu_to_le32(last_startbit);
         rc = put_entry(buf, sizeof(u32), 1, fp);
         if (rc)
             return rc;
 
         buf64[0] = cpu_to_le64(map);
         rc = put_entry(buf64, sizeof(u64), 1, fp);
         if (rc)
             return rc;
     }
     return 0;
 }
 
 u32 ebitmap_hash(const struct ebitmap *e, u32 hash)
 {
     struct ebitmap_node *node;
 
     /* need to change hash even if ebitmap is empty */
     hash = jhash_1word(e->highbit, hash);
     for (node = e->node; node; node = node->next) {
         hash = jhash_1word(node->startbit, hash);
         hash = jhash(node->maps, sizeof(node->maps), hash);
     }
     return hash;
 }
 
 void __init ebitmap_cache_init(void)
 {
     ebitmap_node_cachep = kmem_cache_create("ebitmap_node",
                             sizeof(struct ebitmap_node),
                             0, SLAB_PANIC, NULL);
 }

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