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                 /*
  81                  * We will need to protect whole execve() operation when GC
  82                  * starts kfree()ing "struct tomoyo_domain_info" because
  83                  * bprm->cred->security points to "struct tomoyo_domain_info"
  84                  * but "struct tomoyo_domain_info" does not have a refcounter.
  85                  */
  86                 const int idx = tomoyo_read_lock();
  87                 const int err = tomoyo_find_next_domain(bprm);
  88                 tomoyo_read_unlock(idx);
  89                 return err;
  90         }
  91         /*
  92          * Read permission is checked against interpreters using next domain.
  93          * '1' is the result of open_to_namei_flags(O_RDONLY).
  94          */
  95         return tomoyo_check_open_permission(domain, &bprm->file->f_path, 1);
  96 }
  97
  98 static int tomoyo_path_truncate(struct path *path, loff_t length,
  99                                 unsigned int time_attrs)
 100 {
 101         return tomoyo_check_1path_perm(tomoyo_domain(),
 102                                        TOMOYO_TYPE_TRUNCATE_ACL,
 103                                        path);
 104 }
 105
 106 static int tomoyo_path_unlink(struct path *parent, struct dentry *dentry)
 107 {
 108         struct path path = { parent->mnt, dentry };
 109         return tomoyo_check_1path_perm(tomoyo_domain(),
 110                                        TOMOYO_TYPE_UNLINK_ACL,
 111                                        &path);
 112 }
 113
 114 static int tomoyo_path_mkdir(struct path *parent, struct dentry *dentry,
 115                              int mode)
 116 {
 117         struct path path = { parent->mnt, dentry };
 118         return tomoyo_check_1path_perm(tomoyo_domain(),
 119                                        TOMOYO_TYPE_MKDIR_ACL,
 120                                        &path);
 121 }
 122
 123 static int tomoyo_path_rmdir(struct path *parent, struct dentry *dentry)
 124 {
 125         struct path path = { parent->mnt, dentry };
 126         return tomoyo_check_1path_perm(tomoyo_domain(),
 127                                        TOMOYO_TYPE_RMDIR_ACL,
 128                                        &path);
 129 }
 130
 131 static int tomoyo_path_symlink(struct path *parent, struct dentry *dentry,
 132                                const char *old_name)
 133 {
 134         struct path path = { parent->mnt, dentry };
 135         return tomoyo_check_1path_perm(tomoyo_domain(),
 136                                        TOMOYO_TYPE_SYMLINK_ACL,
 137                                        &path);
 138 }
 139
 140 static int tomoyo_path_mknod(struct path *parent, struct dentry *dentry,
 141                              int mode, unsigned int dev)
 142 {
 143         struct path path = { parent->mnt, dentry };
 144         int type = TOMOYO_TYPE_CREATE_ACL;
 145
 146         switch (mode & S_IFMT) {
 147         case S_IFCHR:
 148                 type = TOMOYO_TYPE_MKCHAR_ACL;
 149                 break;
 150         case S_IFBLK:
 151                 type = TOMOYO_TYPE_MKBLOCK_ACL;
 152                 break;
 153         case S_IFIFO:
 154                 type = TOMOYO_TYPE_MKFIFO_ACL;
 155                 break;
 156         case S_IFSOCK:
 157                 type = TOMOYO_TYPE_MKSOCK_ACL;
 158                 break;
 159         }
 160         return tomoyo_check_1path_perm(tomoyo_domain(),
 161                                        type, &path);
 162 }
 163
 164 static int tomoyo_path_link(struct dentry *old_dentry, struct path *new_dir,
 165                             struct dentry *new_dentry)
 166 {
 167         struct path path1 = { new_dir->mnt, old_dentry };
 168         struct path path2 = { new_dir->mnt, new_dentry };
 169         return tomoyo_check_2path_perm(tomoyo_domain(),
 170                                        TOMOYO_TYPE_LINK_ACL,
 171                                        &path1, &path2);
 172 }
 173
 174 static int tomoyo_path_rename(struct path *old_parent,
 175                               struct dentry *old_dentry,
 176                               struct path *new_parent,
 177                               struct dentry *new_dentry)
 178 {
 179         struct path path1 = { old_parent->mnt, old_dentry };
 180         struct path path2 = { new_parent->mnt, new_dentry };
 181         return tomoyo_check_2path_perm(tomoyo_domain(),
 182                                        TOMOYO_TYPE_RENAME_ACL,
 183                                        &path1, &path2);
 184 }
 185
 186 static int tomoyo_file_fcntl(struct file *file, unsigned int cmd,
 187                              unsigned long arg)
 188 {
 189         if (cmd == F_SETFL && ((arg ^ file->f_flags) & O_APPEND))
 190                 return tomoyo_check_rewrite_permission(tomoyo_domain(), file);
 191         return 0;
 192 }
 193
 194 static int tomoyo_dentry_open(struct file *f, const struct cred *cred)
 195 {
 196         int flags = f->f_flags;
 197
 198         if ((flags + 1) & O_ACCMODE)
 199                 flags++;
 200         flags |= f->f_flags & (O_APPEND | O_TRUNC);
 201         /* Don't check read permission here if called from do_execve(). */
 202         if (current->in_execve)
 203                 return 0;
 204         return tomoyo_check_open_permission(tomoyo_domain(), &f->f_path, flags);
 205 }
 206
 207 static int tomoyo_file_ioctl(struct file *file, unsigned int cmd,
 208                              unsigned long arg)
 209 {
 210         return tomoyo_check_1path_perm(tomoyo_domain(), TOMOYO_TYPE_IOCTL_ACL,
 211                                        &file->f_path);
 212 }
 213
 214 static int tomoyo_path_chmod(struct dentry *dentry, struct vfsmount *mnt,
 215                              mode_t mode)
 216 {
 217         struct path path = { mnt, dentry };
 218         return tomoyo_check_1path_perm(tomoyo_domain(), TOMOYO_TYPE_CHMOD_ACL,
 219                                        &path);
 220 }
 221
 222 static int tomoyo_path_chown(struct path *path, uid_t uid, gid_t gid)
 223 {
 224         int error = 0;
 225         if (uid != (uid_t) -1)
 226                 error = tomoyo_check_1path_perm(tomoyo_domain(),
 227                                                 TOMOYO_TYPE_CHOWN_ACL, path);
 228         if (!error && gid != (gid_t) -1)
 229                 error = tomoyo_check_1path_perm(tomoyo_domain(),
 230                                                 TOMOYO_TYPE_CHGRP_ACL, path);
 231         return error;
 232 }
 233
 234 static int tomoyo_path_chroot(struct path *path)
 235 {
 236         return tomoyo_check_1path_perm(tomoyo_domain(), TOMOYO_TYPE_CHROOT_ACL,
 237                                        path);
 238 }
 239
 240 static int tomoyo_sb_mount(char *dev_name, struct path *path,
 241                            char *type, unsigned long flags, void *data)
 242 {
 243         return tomoyo_check_1path_perm(tomoyo_domain(), TOMOYO_TYPE_MOUNT_ACL,
 244                                        path);
 245 }
 246
 247 static int tomoyo_sb_umount(struct vfsmount *mnt, int flags)
 248 {
 249         struct path path = { mnt, mnt->mnt_root };
 250         return tomoyo_check_1path_perm(tomoyo_domain(), TOMOYO_TYPE_UMOUNT_ACL,
 251                                        &path);
 252 }
 253
 254 static int tomoyo_sb_pivotroot(struct path *old_path, struct path *new_path)
 255 {
 256         return tomoyo_check_2path_perm(tomoyo_domain(),
 257                                        TOMOYO_TYPE_PIVOT_ROOT_ACL,
 258                                        new_path, old_path);
 259 }
 260
 261 /*
 262  * tomoyo_security_ops is a "struct security_operations" which is used for
 263  * registering TOMOYO.
 264  */
 265 static struct security_operations tomoyo_security_ops = {
 266         .name                = "tomoyo",
 267         .cred_alloc_blank    = tomoyo_cred_alloc_blank,
 268         .cred_prepare        = tomoyo_cred_prepare,
 269         .cred_transfer       = tomoyo_cred_transfer,
 270         .bprm_set_creds      = tomoyo_bprm_set_creds,
 271         .bprm_check_security = tomoyo_bprm_check_security,
 272         .file_fcntl          = tomoyo_file_fcntl,
 273         .dentry_open         = tomoyo_dentry_open,
 274         .path_truncate       = tomoyo_path_truncate,
 275         .path_unlink         = tomoyo_path_unlink,
 276         .path_mkdir          = tomoyo_path_mkdir,
 277         .path_rmdir          = tomoyo_path_rmdir,
 278         .path_symlink        = tomoyo_path_symlink,
 279         .path_mknod          = tomoyo_path_mknod,
 280         .path_link           = tomoyo_path_link,
 281         .path_rename         = tomoyo_path_rename,
 282         .file_ioctl          = tomoyo_file_ioctl,
 283         .path_chmod          = tomoyo_path_chmod,
 284         .path_chown          = tomoyo_path_chown,
 285         .path_chroot         = tomoyo_path_chroot,
 286         .sb_mount            = tomoyo_sb_mount,
 287         .sb_umount           = tomoyo_sb_umount,
 288         .sb_pivotroot        = tomoyo_sb_pivotroot,
 289 };
 290
 291 /* Lock for GC. */
 292 struct srcu_struct tomoyo_ss;
 293
 294 static int __init tomoyo_init(void)
 295 {
 296         struct cred *cred = (struct cred *) current_cred();
 297
 298         if (!security_module_enable(&tomoyo_security_ops))
 299                 return 0;
 300         /* register ourselves with the security framework */
 301         if (register_security(&tomoyo_security_ops) ||
 302             init_srcu_struct(&tomoyo_ss))
 303                 panic("Failure registering TOMOYO Linux");
 304         printk(KERN_INFO "TOMOYO Linux initialized\n");
 305         cred->security = &tomoyo_kernel_domain;
 306         tomoyo_realpath_init();
 307         return 0;
 308 }
 309
 310 security_initcall(tomoyo_init);