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         /*
  55          * Load policy if /sbin/tomoyo-init exists and /sbin/init is requested
  56          * for the first time.
  57          */
  58         if (!tomoyo_policy_loaded)
  59                 tomoyo_load_policy(bprm->filename);
  60         /*
  61          * Release reference to "struct tomoyo_domain_info" stored inside
  62          * "bprm->cred->security". New reference to "struct tomoyo_domain_info"
  63          * stored inside "bprm->cred->security" will be acquired later inside
  64          * tomoyo_find_next_domain().
  65          */
  66         atomic_dec(&((struct tomoyo_domain_info *)
  67                      bprm->cred->security)->users);
  68         /*
  69          * Tell tomoyo_bprm_check_security() is called for the first time of an
  70          * execve operation.
  71          */
  72         bprm->cred->security = NULL;
  73         return 0;
  74 }
  75
  76 static int tomoyo_bprm_check_security(struct linux_binprm *bprm)
  77 {
  78         struct tomoyo_domain_info *domain = bprm->cred->security;
  79
  80         /*
  81          * Execute permission is checked against pathname passed to do_execve()
  82          * using current domain.
  83          */
  84         if (!domain) {
  85                 const int idx = tomoyo_read_lock();
  86                 const int err = tomoyo_find_next_domain(bprm);
  87                 tomoyo_read_unlock(idx);
  88                 return err;
  89         }
  90         /*
  91          * Read permission is checked against interpreters using next domain.
  92          */
  93         return tomoyo_check_open_permission(domain, &bprm->file->f_path, O_RDONLY);
  94 }
  95
  96 static int tomoyo_path_truncate(struct path *path)
  97 {
  98         return tomoyo_path_perm(TOMOYO_TYPE_TRUNCATE, path);
  99 }
 100
 101 static int tomoyo_path_unlink(struct path *parent, struct dentry *dentry)
 102 {
 103         struct path path = { parent->mnt, dentry };
 104         return tomoyo_path_perm(TOMOYO_TYPE_UNLINK, &path);
 105 }
 106
 107 static int tomoyo_path_mkdir(struct path *parent, struct dentry *dentry,
 108                              int mode)
 109 {
 110         struct path path = { parent->mnt, dentry };
 111         return tomoyo_path_number_perm(TOMOYO_TYPE_MKDIR, &path,
 112                                        mode & S_IALLUGO);
 113 }
 114
 115 static int tomoyo_path_rmdir(struct path *parent, struct dentry *dentry)
 116 {
 117         struct path path = { parent->mnt, dentry };
 118         return tomoyo_path_perm(TOMOYO_TYPE_RMDIR, &path);
 119 }
 120
 121 static int tomoyo_path_symlink(struct path *parent, struct dentry *dentry,
 122                                const char *old_name)
 123 {
 124         struct path path = { parent->mnt, dentry };
 125         return tomoyo_path_perm(TOMOYO_TYPE_SYMLINK, &path);
 126 }
 127
 128 static int tomoyo_path_mknod(struct path *parent, struct dentry *dentry,
 129                              int mode, unsigned int dev)
 130 {
 131         struct path path = { parent->mnt, dentry };
 132         int type = TOMOYO_TYPE_CREATE;
 133         const unsigned int perm = mode & S_IALLUGO;
 134
 135         switch (mode & S_IFMT) {
 136         case S_IFCHR:
 137                 type = TOMOYO_TYPE_MKCHAR;
 138                 break;
 139         case S_IFBLK:
 140                 type = TOMOYO_TYPE_MKBLOCK;
 141                 break;
 142         default:
 143                 goto no_dev;
 144         }
 145         return tomoyo_mkdev_perm(type, &path, perm, dev);
 146  no_dev:
 147         switch (mode & S_IFMT) {
 148         case S_IFIFO:
 149                 type = TOMOYO_TYPE_MKFIFO;
 150                 break;
 151         case S_IFSOCK:
 152                 type = TOMOYO_TYPE_MKSOCK;
 153                 break;
 154         }
 155         return tomoyo_path_number_perm(type, &path, perm);
 156 }
 157
 158 static int tomoyo_path_link(struct dentry *old_dentry, struct path *new_dir,
 159                             struct dentry *new_dentry)
 160 {
 161         struct path path1 = { new_dir->mnt, old_dentry };
 162         struct path path2 = { new_dir->mnt, new_dentry };
 163         return tomoyo_path2_perm(TOMOYO_TYPE_LINK, &path1, &path2);
 164 }
 165
 166 static int tomoyo_path_rename(struct path *old_parent,
 167                               struct dentry *old_dentry,
 168                               struct path *new_parent,
 169                               struct dentry *new_dentry)
 170 {
 171         struct path path1 = { old_parent->mnt, old_dentry };
 172         struct path path2 = { new_parent->mnt, new_dentry };
 173         return tomoyo_path2_perm(TOMOYO_TYPE_RENAME, &path1, &path2);
 174 }
 175
 176 static int tomoyo_file_fcntl(struct file *file, unsigned int cmd,
 177                              unsigned long arg)
 178 {
 179         if (cmd == F_SETFL && ((arg ^ file->f_flags) & O_APPEND))
 180                 return tomoyo_path_perm(TOMOYO_TYPE_REWRITE, &file->f_path);
 181         return 0;
 182 }
 183
 184 static int tomoyo_dentry_open(struct file *f, const struct cred *cred)
 185 {
 186         int flags = f->f_flags;
 187         /* Don't check read permission here if called from do_execve(). */
 188         if (current->in_execve)
 189                 return 0;
 190         return tomoyo_check_open_permission(tomoyo_domain(), &f->f_path, flags);
 191 }
 192
 193 static int tomoyo_file_ioctl(struct file *file, unsigned int cmd,
 194                              unsigned long arg)
 195 {
 196         return tomoyo_path_number_perm(TOMOYO_TYPE_IOCTL, &file->f_path, cmd);
 197 }
 198
 199 static int tomoyo_path_chmod(struct dentry *dentry, struct vfsmount *mnt,
 200                              mode_t mode)
 201 {
 202         struct path path = { mnt, dentry };
 203         return tomoyo_path_number_perm(TOMOYO_TYPE_CHMOD, &path,
 204                                        mode & S_IALLUGO);
 205 }
 206
 207 static int tomoyo_path_chown(struct path *path, uid_t uid, gid_t gid)
 208 {
 209         int error = 0;
 210         if (uid != (uid_t) -1)
 211                 error = tomoyo_path_number_perm(TOMOYO_TYPE_CHOWN, path, uid);
 212         if (!error && gid != (gid_t) -1)
 213                 error = tomoyo_path_number_perm(TOMOYO_TYPE_CHGRP, path, gid);
 214         return error;
 215 }
 216
 217 static int tomoyo_path_chroot(struct path *path)
 218 {
 219         return tomoyo_path_perm(TOMOYO_TYPE_CHROOT, path);
 220 }
 221
 222 static int tomoyo_sb_mount(char *dev_name, struct path *path,
 223                            char *type, unsigned long flags, void *data)
 224 {
 225         return tomoyo_mount_permission(dev_name, path, type, flags, data);
 226 }
 227
 228 static int tomoyo_sb_umount(struct vfsmount *mnt, int flags)
 229 {
 230         struct path path = { mnt, mnt->mnt_root };
 231         return tomoyo_path_perm(TOMOYO_TYPE_UMOUNT, &path);
 232 }
 233
 234 static int tomoyo_sb_pivotroot(struct path *old_path, struct path *new_path)
 235 {
 236         return tomoyo_path2_perm(TOMOYO_TYPE_PIVOT_ROOT, new_path, old_path);
 237 }
 238
 239 /*
 240  * tomoyo_security_ops is a "struct security_operations" which is used for
 241  * registering TOMOYO.
 242  */
 243 static struct security_operations tomoyo_security_ops = {
 244         .name                = "tomoyo",
 245         .cred_alloc_blank    = tomoyo_cred_alloc_blank,
 246         .cred_prepare        = tomoyo_cred_prepare,
 247         .cred_transfer       = tomoyo_cred_transfer,
 248         .cred_free           = tomoyo_cred_free,
 249         .bprm_set_creds      = tomoyo_bprm_set_creds,
 250         .bprm_check_security = tomoyo_bprm_check_security,
 251         .file_fcntl          = tomoyo_file_fcntl,
 252         .dentry_open         = tomoyo_dentry_open,
 253         .path_truncate       = tomoyo_path_truncate,
 254         .path_unlink         = tomoyo_path_unlink,
 255         .path_mkdir          = tomoyo_path_mkdir,
 256         .path_rmdir          = tomoyo_path_rmdir,
 257         .path_symlink        = tomoyo_path_symlink,
 258         .path_mknod          = tomoyo_path_mknod,
 259         .path_link           = tomoyo_path_link,
 260         .path_rename         = tomoyo_path_rename,
 261         .file_ioctl          = tomoyo_file_ioctl,
 262         .path_chmod          = tomoyo_path_chmod,
 263         .path_chown          = tomoyo_path_chown,
 264         .path_chroot         = tomoyo_path_chroot,
 265         .sb_mount            = tomoyo_sb_mount,
 266         .sb_umount           = tomoyo_sb_umount,
 267         .sb_pivotroot        = tomoyo_sb_pivotroot,
 268 };
 269
 270 /* Lock for GC. */
 271 struct srcu_struct tomoyo_ss;
 272
 273 static int __init tomoyo_init(void)
 274 {
 275         struct cred *cred = (struct cred *) current_cred();
 276
 277         if (!security_module_enable(&tomoyo_security_ops))
 278                 return 0;
 279         /* register ourselves with the security framework */
 280         if (register_security(&tomoyo_security_ops) ||
 281             init_srcu_struct(&tomoyo_ss))
 282                 panic("Failure registering TOMOYO Linux");
 283         printk(KERN_INFO "TOMOYO Linux initialized\n");
 284         cred->security = &tomoyo_kernel_domain;
 285         tomoyo_mm_init();
 286         return 0;
 287 }
 288
 289 security_initcall(tomoyo_init);