security/tomoyo/tomoyo.c

   1 /*
   2  * security/tomoyo/tomoyo.c
   3  *
   4  * LSM hooks for TOMOYO Linux.
   5  *
   6  * Copyright (C) 2005-2009  NTT DATA CORPORATION
   7  *
   8  * Version: 2.2.0   2009/04/01
   9  *
  10  */
  11
  12 #include <linux/security.h>
  13 #include "common.h"
  14 #include "tomoyo.h"
  15 #include "realpath.h"
  16
  17 static int tomoyo_cred_alloc_blank(struct cred *new, gfp_t gfp)
  18 {
  19         new->security = NULL;
  20         return 0;
  21 }
  22
  23 static int tomoyo_cred_prepare(struct cred *new, const struct cred *old,
  24                                gfp_t gfp)
  25 {
  26         /*
  27          * Since "struct tomoyo_domain_info *" is a sharable pointer,
  28          * we don't need to duplicate.
  29          */
  30         new->security = old->security;
  31         return 0;
  32 }
  33
  34 static void tomoyo_cred_transfer(struct cred *new, const struct cred *old)
  35 {
  36         /*
  37          * Since "struct tomoyo_domain_info *" is a sharable pointer,
  38          * we don't need to duplicate.
  39          */
  40         new->security = old->security;
  41 }
  42
  43 static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
  44 {
  45         int rc;
  46
  47         rc = cap_bprm_set_creds(bprm);
  48         if (rc)
  49                 return rc;
  50
  51         /*
  52          * Do only if this function is called for the first time of an execve
  53          * operation.
  54          */
  55         if (bprm->cred_prepared)
  56                 return 0;
  57         /*
  58          * Load policy if /sbin/tomoyo-init exists and /sbin/init is requested
  59          * for the first time.
  60          */
  61         if (!tomoyo_policy_loaded)
  62                 tomoyo_load_policy(bprm->filename);
  63         /*
  64          * Tell tomoyo_bprm_check_security() is called for the first time of an
  65          * execve operation.
  66          */
  67         bprm->cred->security = NULL;
  68         return 0;
  69 }
  70
  71 static int tomoyo_bprm_check_security(struct linux_binprm *bprm)
  72 {
  73         struct tomoyo_domain_info *domain = bprm->cred->security;
  74
  75         /*
  76          * Execute permission is checked against pathname passed to do_execve()
  77          * using current domain.
  78          */
  79         if (!domain)
  80                 return tomoyo_find_next_domain(bprm);
  81         /*
  82          * Read permission is checked against interpreters using next domain.
  83          * '1' is the result of open_to_namei_flags(O_RDONLY).
  84          */
  85         return tomoyo_check_open_permission(domain, &bprm->file->f_path, 1);
  86 }
  87
  88 #ifdef CONFIG_SYSCTL
  89
  90 static int tomoyo_prepend(char **buffer, int *buflen, const char *str)
  91 {
  92         int namelen = strlen(str);
  93
  94         if (*buflen < namelen)
  95                 return -ENOMEM;
  96         *buflen -= namelen;
  97         *buffer -= namelen;
  98         memcpy(*buffer, str, namelen);
  99         return 0;
 100 }
 101
 102 /**
 103  * tomoyo_sysctl_path - return the realpath of a ctl_table.
 104  * @table: pointer to "struct ctl_table".
 105  *
 106  * Returns realpath(3) of the @table on success.
 107  * Returns NULL on failure.
 108  *
 109  * This function uses tomoyo_alloc(), so the caller must call tomoyo_free()
 110  * if this function didn't return NULL.
 111  */
 112 static char *tomoyo_sysctl_path(struct ctl_table *table)
 113 {
 114         int buflen = TOMOYO_MAX_PATHNAME_LEN;
 115         char *buf = tomoyo_alloc(buflen);
 116         char *end = buf + buflen;
 117         int error = -ENOMEM;
 118
 119         if (!buf)
 120                 return NULL;
 121
 122         *--end = '\0';
 123         buflen--;
 124         while (table) {
 125                 char num[32];
 126                 const char *sp = table->procname;
 127
 128                 if (!sp) {
 129                         memset(num, 0, sizeof(num));
 130                         snprintf(num, sizeof(num) - 1, "=%d=", table->ctl_name);
 131                         sp = num;
 132                 }
 133                 if (tomoyo_prepend(&end, &buflen, sp) ||
 134                     tomoyo_prepend(&end, &buflen, "/"))
 135                         goto out;
 136                 table = table->parent;
 137         }
 138         if (tomoyo_prepend(&end, &buflen, "/proc/sys"))
 139                 goto out;
 140         error = tomoyo_encode(buf, end - buf, end);
 141  out:
 142         if (!error)
 143                 return buf;
 144         tomoyo_free(buf);
 145         return NULL;
 146 }
 147
 148 static int tomoyo_sysctl(struct ctl_table *table, int op)
 149 {
 150         int error;
 151         char *name;
 152
 153         op &= MAY_READ | MAY_WRITE;
 154         if (!op)
 155                 return 0;
 156         name = tomoyo_sysctl_path(table);
 157         if (!name)
 158                 return -ENOMEM;
 159         error = tomoyo_check_file_perm(tomoyo_domain(), name, op);
 160         tomoyo_free(name);
 161         return error;
 162 }
 163 #endif
 164
 165 static int tomoyo_path_truncate(struct path *path, loff_t length,
 166                                 unsigned int time_attrs)
 167 {
 168         return tomoyo_check_1path_perm(tomoyo_domain(),
 169                                        TOMOYO_TYPE_TRUNCATE_ACL,
 170                                        path);
 171 }
 172
 173 static int tomoyo_path_unlink(struct path *parent, struct dentry *dentry)
 174 {
 175         struct path path = { parent->mnt, dentry };
 176         return tomoyo_check_1path_perm(tomoyo_domain(),
 177                                        TOMOYO_TYPE_UNLINK_ACL,
 178                                        &path);
 179 }
 180
 181 static int tomoyo_path_mkdir(struct path *parent, struct dentry *dentry,
 182                              int mode)
 183 {
 184         struct path path = { parent->mnt, dentry };
 185         return tomoyo_check_1path_perm(tomoyo_domain(),
 186                                        TOMOYO_TYPE_MKDIR_ACL,
 187                                        &path);
 188 }
 189
 190 static int tomoyo_path_rmdir(struct path *parent, struct dentry *dentry)
 191 {
 192         struct path path = { parent->mnt, dentry };
 193         return tomoyo_check_1path_perm(tomoyo_domain(),
 194                                        TOMOYO_TYPE_RMDIR_ACL,
 195                                        &path);
 196 }
 197
 198 static int tomoyo_path_symlink(struct path *parent, struct dentry *dentry,
 199                                const char *old_name)
 200 {
 201         struct path path = { parent->mnt, dentry };
 202         return tomoyo_check_1path_perm(tomoyo_domain(),
 203                                        TOMOYO_TYPE_SYMLINK_ACL,
 204                                        &path);
 205 }
 206
 207 static int tomoyo_path_mknod(struct path *parent, struct dentry *dentry,
 208                              int mode, unsigned int dev)
 209 {
 210         struct path path = { parent->mnt, dentry };
 211         int type = TOMOYO_TYPE_CREATE_ACL;
 212
 213         switch (mode & S_IFMT) {
 214         case S_IFCHR:
 215                 type = TOMOYO_TYPE_MKCHAR_ACL;
 216                 break;
 217         case S_IFBLK:
 218                 type = TOMOYO_TYPE_MKBLOCK_ACL;
 219                 break;
 220         case S_IFIFO:
 221                 type = TOMOYO_TYPE_MKFIFO_ACL;
 222                 break;
 223         case S_IFSOCK:
 224                 type = TOMOYO_TYPE_MKSOCK_ACL;
 225                 break;
 226         }
 227         return tomoyo_check_1path_perm(tomoyo_domain(),
 228                                        type, &path);
 229 }
 230
 231 static int tomoyo_path_link(struct dentry *old_dentry, struct path *new_dir,
 232                             struct dentry *new_dentry)
 233 {
 234         struct path path1 = { new_dir->mnt, old_dentry };
 235         struct path path2 = { new_dir->mnt, new_dentry };
 236         return tomoyo_check_2path_perm(tomoyo_domain(),
 237                                        TOMOYO_TYPE_LINK_ACL,
 238                                        &path1, &path2);
 239 }
 240
 241 static int tomoyo_path_rename(struct path *old_parent,
 242                               struct dentry *old_dentry,
 243                               struct path *new_parent,
 244                               struct dentry *new_dentry)
 245 {
 246         struct path path1 = { old_parent->mnt, old_dentry };
 247         struct path path2 = { new_parent->mnt, new_dentry };
 248         return tomoyo_check_2path_perm(tomoyo_domain(),
 249                                        TOMOYO_TYPE_RENAME_ACL,
 250                                        &path1, &path2);
 251 }
 252
 253 static int tomoyo_file_fcntl(struct file *file, unsigned int cmd,
 254                              unsigned long arg)
 255 {
 256         if (cmd == F_SETFL && ((arg ^ file->f_flags) & O_APPEND))
 257                 return tomoyo_check_rewrite_permission(tomoyo_domain(), file);
 258         return 0;
 259 }
 260
 261 static int tomoyo_dentry_open(struct file *f, const struct cred *cred)
 262 {
 263         int flags = f->f_flags;
 264
 265         if ((flags + 1) & O_ACCMODE)
 266                 flags++;
 267         flags |= f->f_flags & (O_APPEND | O_TRUNC);
 268         /* Don't check read permission here if called from do_execve(). */
 269         if (current->in_execve)
 270                 return 0;
 271         return tomoyo_check_open_permission(tomoyo_domain(), &f->f_path, flags);
 272 }
 273
 274 /*
 275  * tomoyo_security_ops is a "struct security_operations" which is used for
 276  * registering TOMOYO.
 277  */
 278 static struct security_operations tomoyo_security_ops = {
 279         .name                = "tomoyo",
 280         .cred_alloc_blank    = tomoyo_cred_alloc_blank,
 281         .cred_prepare        = tomoyo_cred_prepare,
 282         .cred_transfer       = tomoyo_cred_transfer,
 283         .bprm_set_creds      = tomoyo_bprm_set_creds,
 284         .bprm_check_security = tomoyo_bprm_check_security,
 285 #ifdef CONFIG_SYSCTL
 286         .sysctl              = tomoyo_sysctl,
 287 #endif
 288         .file_fcntl          = tomoyo_file_fcntl,
 289         .dentry_open         = tomoyo_dentry_open,
 290         .path_truncate       = tomoyo_path_truncate,
 291         .path_unlink         = tomoyo_path_unlink,
 292         .path_mkdir          = tomoyo_path_mkdir,
 293         .path_rmdir          = tomoyo_path_rmdir,
 294         .path_symlink        = tomoyo_path_symlink,
 295         .path_mknod          = tomoyo_path_mknod,
 296         .path_link           = tomoyo_path_link,
 297         .path_rename         = tomoyo_path_rename,
 298 };
 299
 300 static int __init tomoyo_init(void)
 301 {
 302         struct cred *cred = (struct cred *) current_cred();
 303
 304         if (!security_module_enable(&tomoyo_security_ops))
 305                 return 0;
 306         /* register ourselves with the security framework */
 307         if (register_security(&tomoyo_security_ops))
 308                 panic("Failure registering TOMOYO Linux");
 309         printk(KERN_INFO "TOMOYO Linux initialized\n");
 310         cred->security = &tomoyo_kernel_domain;
 311         tomoyo_realpath_init();
 312         return 0;
 313 }
 314
 315 security_initcall(tomoyo_init);