security/tomoyo/memory.c

   1 /*
   2  * security/tomoyo/memory.c
   3  *
   4  * Memory management functions for TOMOYO.
   5  *
   6  * Copyright (C) 2005-2010  NTT DATA CORPORATION
   7  */
   8
   9 #include <linux/hash.h>
  10 #include <linux/slab.h>
  11 #include "common.h"
  12
  13 /**
  14  * tomoyo_warn_oom - Print out of memory warning message.
  15  *
  16  * @function: Function's name.
  17  */
  18 void tomoyo_warn_oom(const char *function)
  19 {
  20         /* Reduce error messages. */
  21         static pid_t tomoyo_last_pid;
  22         const pid_t pid = current->pid;
  23         if (tomoyo_last_pid != pid) {
  24                 printk(KERN_WARNING "ERROR: Out of memory at %s.\n",
  25                        function);
  26                 tomoyo_last_pid = pid;
  27         }
  28         if (!tomoyo_policy_loaded)
  29                 panic("MAC Initialization failed.\n");
  30 }
  31
  32 /* Memory allocated for policy. */
  33 static atomic_t tomoyo_policy_memory_size;
  34 /* Quota for holding policy. */
  35 static unsigned int tomoyo_quota_for_policy;
  36
  37 /**
  38  * tomoyo_memory_ok - Check memory quota.
  39  *
  40  * @ptr: Pointer to allocated memory.
  41  *
  42  * Returns true on success, false otherwise.
  43  *
  44  * Returns true if @ptr is not NULL and quota not exceeded, false otherwise.
  45  */
  46 bool tomoyo_memory_ok(void *ptr)
  47 {
  48         size_t s = ptr ? ksize(ptr) : 0;
  49         atomic_add(s, &tomoyo_policy_memory_size);
  50         if (ptr && (!tomoyo_quota_for_policy ||
  51                     atomic_read(&tomoyo_policy_memory_size)
  52                     <= tomoyo_quota_for_policy)) {
  53                 memset(ptr, 0, s);
  54                 return true;
  55         }
  56         atomic_sub(s, &tomoyo_policy_memory_size);
  57         tomoyo_warn_oom(__func__);
  58         return false;
  59 }
  60
  61 /**
  62  * tomoyo_commit_ok - Check memory quota.
  63  *
  64  * @data:   Data to copy from.
  65  * @size:   Size in byte.
  66  *
  67  * Returns pointer to allocated memory on success, NULL otherwise.
  68  * @data is zero-cleared on success.
  69  */
  70 void *tomoyo_commit_ok(void *data, const unsigned int size)
  71 {
  72         void *ptr = kzalloc(size, GFP_NOFS);
  73         if (tomoyo_memory_ok(ptr)) {
  74                 memmove(ptr, data, size);
  75                 memset(data, 0, size);
  76                 return ptr;
  77         }
  78         return NULL;
  79 }
  80
  81 /**
  82  * tomoyo_memory_free - Free memory for elements.
  83  *
  84  * @ptr:  Pointer to allocated memory.
  85  */
  86 void tomoyo_memory_free(void *ptr)
  87 {
  88         atomic_sub(ksize(ptr), &tomoyo_policy_memory_size);
  89         kfree(ptr);
  90 }
  91
  92 /*
  93  * tomoyo_name_list is used for holding string data used by TOMOYO.
  94  * Since same string data is likely used for multiple times (e.g.
  95  * "/lib/libc-2.5.so"), TOMOYO shares string data in the form of
  96  * "const struct tomoyo_path_info *".
  97  */
  98 struct list_head tomoyo_name_list[TOMOYO_MAX_HASH];
  99
 100 /**
 101  * tomoyo_get_name - Allocate permanent memory for string data.
 102  *
 103  * @name: The string to store into the permernent memory.
 104  *
 105  * Returns pointer to "struct tomoyo_path_info" on success, NULL otherwise.
 106  */
 107 const struct tomoyo_path_info *tomoyo_get_name(const char *name)
 108 {
 109         struct tomoyo_name_entry *ptr;
 110         unsigned int hash;
 111         int len;
 112         int allocated_len;
 113         struct list_head *head;
 114
 115         if (!name)
 116                 return NULL;
 117         len = strlen(name) + 1;
 118         hash = full_name_hash((const unsigned char *) name, len - 1);
 119         head = &tomoyo_name_list[hash_long(hash, TOMOYO_HASH_BITS)];
 120         if (mutex_lock_interruptible(&tomoyo_policy_lock))
 121                 return NULL;
 122         list_for_each_entry(ptr, head, list) {
 123                 if (hash != ptr->entry.hash || strcmp(name, ptr->entry.name))
 124                         continue;
 125                 atomic_inc(&ptr->users);
 126                 goto out;
 127         }
 128         ptr = kzalloc(sizeof(*ptr) + len, GFP_NOFS);
 129         allocated_len = ptr ? ksize(ptr) : 0;
 130         if (!ptr || (tomoyo_quota_for_policy &&
 131                      atomic_read(&tomoyo_policy_memory_size) + allocated_len
 132                      > tomoyo_quota_for_policy)) {
 133                 kfree(ptr);
 134                 ptr = NULL;
 135                 tomoyo_warn_oom(__func__);
 136                 goto out;
 137         }
 138         atomic_add(allocated_len, &tomoyo_policy_memory_size);
 139         ptr->entry.name = ((char *) ptr) + sizeof(*ptr);
 140         memmove((char *) ptr->entry.name, name, len);
 141         atomic_set(&ptr->users, 1);
 142         tomoyo_fill_path_info(&ptr->entry);
 143         list_add_tail(&ptr->list, head);
 144  out:
 145         mutex_unlock(&tomoyo_policy_lock);
 146         return ptr ? &ptr->entry : NULL;
 147 }
 148
 149 /**
 150  * tomoyo_mm_init - Initialize mm related code.
 151  */
 152 void __init tomoyo_mm_init(void)
 153 {
 154         int idx;
 155
 156         BUILD_BUG_ON(TOMOYO_MAX_PATHNAME_LEN > PATH_MAX);
 157         for (idx = 0; idx < TOMOYO_MAX_HASH; idx++)
 158                 INIT_LIST_HEAD(&tomoyo_name_list[idx]);
 159         INIT_LIST_HEAD(&tomoyo_kernel_domain.acl_info_list);
 160         tomoyo_kernel_domain.domainname = tomoyo_get_name(TOMOYO_ROOT_NAME);
 161         list_add_tail_rcu(&tomoyo_kernel_domain.list, &tomoyo_domain_list);
 162         idx = tomoyo_read_lock();
 163         if (tomoyo_find_domain(TOMOYO_ROOT_NAME) != &tomoyo_kernel_domain)
 164                 panic("Can't register tomoyo_kernel_domain");
 165         {
 166                 /* Load built-in policy. */
 167                 tomoyo_write_domain_initializer_policy("/sbin/hotplug",
 168                                                        false, false);
 169                 tomoyo_write_domain_initializer_policy("/sbin/modprobe",
 170                                                        false, false);
 171         }
 172         tomoyo_read_unlock(idx);
 173 }
 174
 175
 176 /* Memory allocated for query lists. */
 177 unsigned int tomoyo_query_memory_size;
 178 /* Quota for holding query lists. */
 179 unsigned int tomoyo_quota_for_query;
 180
 181 /**
 182  * tomoyo_read_memory_counter - Check for memory usage in bytes.
 183  *
 184  * @head: Pointer to "struct tomoyo_io_buffer".
 185  *
 186  * Returns memory usage.
 187  */
 188 int tomoyo_read_memory_counter(struct tomoyo_io_buffer *head)
 189 {
 190         if (!head->read_eof) {
 191                 const unsigned int policy
 192                         = atomic_read(&tomoyo_policy_memory_size);
 193                 const unsigned int query = tomoyo_query_memory_size;
 194                 char buffer[64];
 195
 196                 memset(buffer, 0, sizeof(buffer));
 197                 if (tomoyo_quota_for_policy)
 198                         snprintf(buffer, sizeof(buffer) - 1,
 199                                  "   (Quota: %10u)",
 200                                  tomoyo_quota_for_policy);
 201                 else
 202                         buffer[0] = '\0';
 203                 tomoyo_io_printf(head, "Policy:       %10u%s\n", policy,
 204                                  buffer);
 205                 if (tomoyo_quota_for_query)
 206                         snprintf(buffer, sizeof(buffer) - 1,
 207                                  "   (Quota: %10u)",
 208                                  tomoyo_quota_for_query);
 209                 else
 210                         buffer[0] = '\0';
 211                 tomoyo_io_printf(head, "Query lists:  %10u%s\n", query,
 212                                  buffer);
 213                 tomoyo_io_printf(head, "Total:        %10u\n", policy + query);
 214                 head->read_eof = true;
 215         }
 216         return 0;
 217 }
 218
 219 /**
 220  * tomoyo_write_memory_quota - Set memory quota.
 221  *
 222  * @head: Pointer to "struct tomoyo_io_buffer".
 223  *
 224  * Returns 0.
 225  */
 226 int tomoyo_write_memory_quota(struct tomoyo_io_buffer *head)
 227 {
 228         char *data = head->write_buf;
 229         unsigned int size;
 230
 231         if (sscanf(data, "Policy: %u", &size) == 1)
 232                 tomoyo_quota_for_policy = size;
 233         else if (sscanf(data, "Query lists: %u", &size) == 1)
 234                 tomoyo_quota_for_query = size;
 235         return 0;
 236 }