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