security/tomoyo/tomoyo.c

   1 /*
   2  * security/tomoyo/tomoyo.c
   3  *
   4  * LSM hooks for TOMOYO Linux.
   5  *
   6  * Copyright (C) 2005-2010  NTT DATA CORPORATION
   7  */
   8
   9 #include <linux/security.h>
  10 #include "common.h"
  11
  12 static int tomoyo_cred_alloc_blank(struct cred *new, gfp_t gfp)
  13 {
  14         new->security = NULL;
  15         return 0;
  16 }
  17
  18 static int tomoyo_cred_prepare(struct cred *new, const struct cred *old,
  19                                gfp_t gfp)
  20 {
  21         struct tomoyo_domain_info *domain = old->security;
  22         new->security = domain;
  23         if (domain)
  24                 atomic_inc(&domain->users);
  25         return 0;
  26 }
  27
  28 static void tomoyo_cred_transfer(struct cred *new, const struct cred *old)
  29 {
  30         tomoyo_cred_prepare(new, old, 0);
  31 }
  32
  33 static void tomoyo_cred_free(struct cred *cred)
  34 {
  35         struct tomoyo_domain_info *domain = cred->security;
  36         if (domain)
  37                 atomic_dec(&domain->users);
  38 }
  39
  40 static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
  41 {
  42         int rc;
  43
  44         rc = cap_bprm_set_creds(bprm);
  45         if (rc)
  46                 return rc;
  47
  48         /*
  49          * Do only if this function is called for the first time of an execve
  50          * operation.
  51          */
  52         if (bprm->cred_prepared)
  53                 return 0;
  54 #ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
  55         /*
  56          * Load policy if /sbin/tomoyo-init exists and /sbin/init is requested
  57          * for the first time.
  58          */
  59         if (!tomoyo_policy_loaded)
  60                 tomoyo_load_policy(bprm->filename);
  61 #endif
  62         /*
  63          * Release reference to "struct tomoyo_domain_info" stored inside
  64          * "bprm->cred->security". New reference to "struct tomoyo_domain_info"
  65          * stored inside "bprm->cred->security" will be acquired later inside
  66          * tomoyo_find_next_domain().
  67          */
  68         atomic_dec(&((struct tomoyo_domain_info *)
  69                      bprm->cred->security)->users);
  70         /*
  71          * Tell tomoyo_bprm_check_security() is called for the first time of an
  72          * execve operation.
  73          */
  74         bprm->cred->security = NULL;
  75         return 0;
  76 }
  77
  78 static int tomoyo_bprm_check_security(struct linux_binprm *bprm)
  79 {
  80         struct tomoyo_domain_info *domain = bprm->cred->security;
  81
  82         /*
  83          * Execute permission is checked against pathname passed to do_execve()
  84          * using current domain.
  85          */
  86         if (!domain) {
  87                 const int idx = tomoyo_read_lock();
  88                 const int err = tomoyo_find_next_domain(bprm);
  89                 tomoyo_read_unlock(idx);
  90                 return err;
  91         }
  92         /*
  93          * Read permission is checked against interpreters using next domain.
  94          */
  95         return tomoyo_check_open_permission(domain, &bprm->file->f_path, O_RDONLY);
  96 }
  97
  98 static int tomoyo_inode_getattr(struct vfsmount *mnt, struct dentry *dentry)
  99 {
 100         struct path path = { mnt, dentry };
 101         return tomoyo_path_perm(TOMOYO_TYPE_GETATTR, &path, NULL);
 102 }
 103
 104 static int tomoyo_path_truncate(struct path *path)
 105 {
 106         return tomoyo_path_perm(TOMOYO_TYPE_TRUNCATE, path, NULL);
 107 }
 108
 109 static int tomoyo_path_unlink(struct path *parent, struct dentry *dentry)
 110 {
 111         struct path path = { parent->mnt, dentry };
 112         return tomoyo_path_perm(TOMOYO_TYPE_UNLINK, &path, NULL);
 113 }
 114
 115 static int tomoyo_path_mkdir(struct path *parent, struct dentry *dentry,
 116                              int mode)
 117 {
 118         struct path path = { parent->mnt, dentry };
 119         return tomoyo_path_number_perm(TOMOYO_TYPE_MKDIR, &path,
 120                                        mode & S_IALLUGO);
 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_path_perm(TOMOYO_TYPE_RMDIR, &path, NULL);
 127 }
 128
 129 static int tomoyo_path_symlink(struct path *parent, struct dentry *dentry,
 130                                const char *old_name)
 131 {
 132         struct path path = { parent->mnt, dentry };
 133         return tomoyo_path_perm(TOMOYO_TYPE_SYMLINK, &path, old_name);
 134 }
 135
 136 static int tomoyo_path_mknod(struct path *parent, struct dentry *dentry,
 137                              int mode, unsigned int dev)
 138 {
 139         struct path path = { parent->mnt, dentry };
 140         int type = TOMOYO_TYPE_CREATE;
 141         const unsigned int perm = mode & S_IALLUGO;
 142
 143         switch (mode & S_IFMT) {
 144         case S_IFCHR:
 145                 type = TOMOYO_TYPE_MKCHAR;
 146                 break;
 147         case S_IFBLK:
 148                 type = TOMOYO_TYPE_MKBLOCK;
 149                 break;
 150         default:
 151                 goto no_dev;
 152         }
 153         return tomoyo_mkdev_perm(type, &path, perm, dev);
 154  no_dev:
 155         switch (mode & S_IFMT) {
 156         case S_IFIFO:
 157                 type = TOMOYO_TYPE_MKFIFO;
 158                 break;
 159         case S_IFSOCK:
 160                 type = TOMOYO_TYPE_MKSOCK;
 161                 break;
 162         }
 163         return tomoyo_path_number_perm(type, &path, perm);
 164 }
 165
 166 static int tomoyo_path_link(struct dentry *old_dentry, struct path *new_dir,
 167                             struct dentry *new_dentry)
 168 {
 169         struct path path1 = { new_dir->mnt, old_dentry };
 170         struct path path2 = { new_dir->mnt, new_dentry };
 171         return tomoyo_path2_perm(TOMOYO_TYPE_LINK, &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_path2_perm(TOMOYO_TYPE_RENAME, &path1, &path2);
 182 }
 183
 184 static int tomoyo_file_fcntl(struct file *file, unsigned int cmd,
 185                              unsigned long arg)
 186 {
 187         if (!(cmd == F_SETFL && ((arg ^ file->f_flags) & O_APPEND)))
 188                 return 0;
 189         return tomoyo_check_open_permission(tomoyo_domain(), &file->f_path,
 190                                             O_WRONLY | (arg & O_APPEND));
 191 }
 192
 193 static int tomoyo_dentry_open(struct file *f, const struct cred *cred)
 194 {
 195         int flags = f->f_flags;
 196         /* Don't check read permission here if called from do_execve(). */
 197         if (current->in_execve)
 198                 return 0;
 199         return tomoyo_check_open_permission(tomoyo_domain(), &f->f_path, flags);
 200 }
 201
 202 static int tomoyo_file_ioctl(struct file *file, unsigned int cmd,
 203                              unsigned long arg)
 204 {
 205         return tomoyo_path_number_perm(TOMOYO_TYPE_IOCTL, &file->f_path, cmd);
 206 }
 207
 208 static int tomoyo_path_chmod(struct dentry *dentry, struct vfsmount *mnt,
 209                              mode_t mode)
 210 {
 211         struct path path = { mnt, dentry };
 212         return tomoyo_path_number_perm(TOMOYO_TYPE_CHMOD, &path,
 213                                        mode & S_IALLUGO);
 214 }
 215
 216 static int tomoyo_path_chown(struct path *path, uid_t uid, gid_t gid)
 217 {
 218         int error = 0;
 219         if (uid != (uid_t) -1)
 220                 error = tomoyo_path_number_perm(TOMOYO_TYPE_CHOWN, path, uid);
 221         if (!error && gid != (gid_t) -1)
 222                 error = tomoyo_path_number_perm(TOMOYO_TYPE_CHGRP, path, gid);
 223         return error;
 224 }
 225
 226 static int tomoyo_path_chroot(struct path *path)
 227 {
 228         return tomoyo_path_perm(TOMOYO_TYPE_CHROOT, path, NULL);
 229 }
 230
 231 static int tomoyo_sb_mount(char *dev_name, struct path *path,
 232                            char *type, unsigned long flags, void *data)
 233 {
 234         return tomoyo_mount_permission(dev_name, path, type, flags, data);
 235 }
 236
 237 static int tomoyo_sb_umount(struct vfsmount *mnt, int flags)
 238 {
 239         struct path path = { mnt, mnt->mnt_root };
 240         return tomoyo_path_perm(TOMOYO_TYPE_UMOUNT, &path, NULL);
 241 }
 242
 243 static int tomoyo_sb_pivotroot(struct path *old_path, struct path *new_path)
 244 {
 245         return tomoyo_path2_perm(TOMOYO_TYPE_PIVOT_ROOT, new_path, old_path);
 246 }
 247
 248 /*
 249  * tomoyo_security_ops is a "struct security_operations" which is used for
 250  * registering TOMOYO.
 251  */
 252 static struct security_operations tomoyo_security_ops = {
 253         .name                = "tomoyo",
 254         .cred_alloc_blank    = tomoyo_cred_alloc_blank,
 255         .cred_prepare        = tomoyo_cred_prepare,
 256         .cred_transfer       = tomoyo_cred_transfer,
 257         .cred_free           = tomoyo_cred_free,
 258         .bprm_set_creds      = tomoyo_bprm_set_creds,
 259         .bprm_check_security = tomoyo_bprm_check_security,
 260         .file_fcntl          = tomoyo_file_fcntl,
 261         .dentry_open         = tomoyo_dentry_open,
 262         .path_truncate       = tomoyo_path_truncate,
 263         .path_unlink         = tomoyo_path_unlink,
 264         .path_mkdir          = tomoyo_path_mkdir,
 265         .path_rmdir          = tomoyo_path_rmdir,
 266         .path_symlink        = tomoyo_path_symlink,
 267         .path_mknod          = tomoyo_path_mknod,
 268         .path_link           = tomoyo_path_link,
 269         .path_rename         = tomoyo_path_rename,
 270         .inode_getattr       = tomoyo_inode_getattr,
 271         .file_ioctl          = tomoyo_file_ioctl,
 272         .path_chmod          = tomoyo_path_chmod,
 273         .path_chown          = tomoyo_path_chown,
 274         .path_chroot         = tomoyo_path_chroot,
 275         .sb_mount            = tomoyo_sb_mount,
 276         .sb_umount           = tomoyo_sb_umount,
 277         .sb_pivotroot        = tomoyo_sb_pivotroot,
 278 };
 279
 280 /* Lock for GC. */
 281 struct srcu_struct tomoyo_ss;
 282
 283 static int __init tomoyo_init(void)
 284 {
 285         struct cred *cred = (struct cred *) current_cred();
 286
 287         if (!security_module_enable(&tomoyo_security_ops))
 288                 return 0;
 289         /* register ourselves with the security framework */
 290         if (register_security(&tomoyo_security_ops) ||
 291             init_srcu_struct(&tomoyo_ss))
 292                 panic("Failure registering TOMOYO Linux");
 293         printk(KERN_INFO "TOMOYO Linux initialized\n");
 294         cred->security = &tomoyo_kernel_domain;
 295         tomoyo_mm_init();
 296         return 0;
 297 }
 298
 299 security_initcall(tomoyo_init);