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, loff_t length,
  97                                 unsigned int time_attrs)
  98 {
  99         return tomoyo_path_perm(TOMOYO_TYPE_TRUNCATE, path);
 100 }
 101
 102 static int tomoyo_path_unlink(struct path *parent, struct dentry *dentry)
 103 {
 104         struct path path = { parent->mnt, dentry };
 105         return tomoyo_path_perm(TOMOYO_TYPE_UNLINK, &path);
 106 }
 107
 108 static int tomoyo_path_mkdir(struct path *parent, struct dentry *dentry,
 109                              int mode)
 110 {
 111         struct path path = { parent->mnt, dentry };
 112         return tomoyo_path_number_perm(TOMOYO_TYPE_MKDIR, &path,
 113                                        mode & S_IALLUGO);
 114 }
 115
 116 static int tomoyo_path_rmdir(struct path *parent, struct dentry *dentry)
 117 {
 118         struct path path = { parent->mnt, dentry };
 119         return tomoyo_path_perm(TOMOYO_TYPE_RMDIR, &path);
 120 }
 121
 122 static int tomoyo_path_symlink(struct path *parent, struct dentry *dentry,
 123                                const char *old_name)
 124 {
 125         struct path path = { parent->mnt, dentry };
 126         return tomoyo_path_perm(TOMOYO_TYPE_SYMLINK, &path);
 127 }
 128
 129 static int tomoyo_path_mknod(struct path *parent, struct dentry *dentry,
 130                              int mode, unsigned int dev)
 131 {
 132         struct path path = { parent->mnt, dentry };
 133         int type = TOMOYO_TYPE_CREATE;
 134         const unsigned int perm = mode & S_IALLUGO;
 135
 136         switch (mode & S_IFMT) {
 137         case S_IFCHR:
 138                 type = TOMOYO_TYPE_MKCHAR;
 139                 break;
 140         case S_IFBLK:
 141                 type = TOMOYO_TYPE_MKBLOCK;
 142                 break;
 143         default:
 144                 goto no_dev;
 145         }
 146         return tomoyo_path_number3_perm(type, &path, perm, dev);
 147  no_dev:
 148         switch (mode & S_IFMT) {
 149         case S_IFIFO:
 150                 type = TOMOYO_TYPE_MKFIFO;
 151                 break;
 152         case S_IFSOCK:
 153                 type = TOMOYO_TYPE_MKSOCK;
 154                 break;
 155         }
 156         return tomoyo_path_number_perm(type, &path, perm);
 157 }
 158
 159 static int tomoyo_path_link(struct dentry *old_dentry, struct path *new_dir,
 160                             struct dentry *new_dentry)
 161 {
 162         struct path path1 = { new_dir->mnt, old_dentry };
 163         struct path path2 = { new_dir->mnt, new_dentry };
 164         return tomoyo_path2_perm(TOMOYO_TYPE_LINK, &path1, &path2);
 165 }
 166
 167 static int tomoyo_path_rename(struct path *old_parent,
 168                               struct dentry *old_dentry,
 169                               struct path *new_parent,
 170                               struct dentry *new_dentry)
 171 {
 172         struct path path1 = { old_parent->mnt, old_dentry };
 173         struct path path2 = { new_parent->mnt, new_dentry };
 174         return tomoyo_path2_perm(TOMOYO_TYPE_RENAME, &path1, &path2);
 175 }
 176
 177 static int tomoyo_file_fcntl(struct file *file, unsigned int cmd,
 178                              unsigned long arg)
 179 {
 180         if (cmd == F_SETFL && ((arg ^ file->f_flags) & O_APPEND))
 181                 return tomoyo_path_perm(TOMOYO_TYPE_REWRITE, &file->f_path);
 182         return 0;
 183 }
 184
 185 static int tomoyo_dentry_open(struct file *f, const struct cred *cred)
 186 {
 187         int flags = f->f_flags;
 188         /* Don't check read permission here if called from do_execve(). */
 189         if (current->in_execve)
 190                 return 0;
 191         return tomoyo_check_open_permission(tomoyo_domain(), &f->f_path, flags);
 192 }
 193
 194 static int tomoyo_file_ioctl(struct file *file, unsigned int cmd,
 195                              unsigned long arg)
 196 {
 197         return tomoyo_path_number_perm(TOMOYO_TYPE_IOCTL, &file->f_path, cmd);
 198 }
 199
 200 static int tomoyo_path_chmod(struct dentry *dentry, struct vfsmount *mnt,
 201                              mode_t mode)
 202 {
 203         struct path path = { mnt, dentry };
 204         return tomoyo_path_number_perm(TOMOYO_TYPE_CHMOD, &path,
 205                                        mode & S_IALLUGO);
 206 }
 207
 208 static int tomoyo_path_chown(struct path *path, uid_t uid, gid_t gid)
 209 {
 210         int error = 0;
 211         if (uid != (uid_t) -1)
 212                 error = tomoyo_path_number_perm(TOMOYO_TYPE_CHOWN, path, uid);
 213         if (!error && gid != (gid_t) -1)
 214                 error = tomoyo_path_number_perm(TOMOYO_TYPE_CHGRP, path, gid);
 215         return error;
 216 }
 217
 218 static int tomoyo_path_chroot(struct path *path)
 219 {
 220         return tomoyo_path_perm(TOMOYO_TYPE_CHROOT, path);
 221 }
 222
 223 static int tomoyo_sb_mount(char *dev_name, struct path *path,
 224                            char *type, unsigned long flags, void *data)
 225 {
 226         return tomoyo_mount_permission(dev_name, path, type, flags, data);
 227 }
 228
 229 static int tomoyo_sb_umount(struct vfsmount *mnt, int flags)
 230 {
 231         struct path path = { mnt, mnt->mnt_root };
 232         return tomoyo_path_perm(TOMOYO_TYPE_UMOUNT, &path);
 233 }
 234
 235 static int tomoyo_sb_pivotroot(struct path *old_path, struct path *new_path)
 236 {
 237         return tomoyo_path2_perm(TOMOYO_TYPE_PIVOT_ROOT, new_path, old_path);
 238 }
 239
 240 /*
 241  * tomoyo_security_ops is a "struct security_operations" which is used for
 242  * registering TOMOYO.
 243  */
 244 static struct security_operations tomoyo_security_ops = {
 245         .name                = "tomoyo",
 246         .cred_alloc_blank    = tomoyo_cred_alloc_blank,
 247         .cred_prepare        = tomoyo_cred_prepare,
 248         .cred_transfer       = tomoyo_cred_transfer,
 249         .cred_free           = tomoyo_cred_free,
 250         .bprm_set_creds      = tomoyo_bprm_set_creds,
 251         .bprm_check_security = tomoyo_bprm_check_security,
 252         .file_fcntl          = tomoyo_file_fcntl,
 253         .dentry_open         = tomoyo_dentry_open,
 254         .path_truncate       = tomoyo_path_truncate,
 255         .path_unlink         = tomoyo_path_unlink,
 256         .path_mkdir          = tomoyo_path_mkdir,
 257         .path_rmdir          = tomoyo_path_rmdir,
 258         .path_symlink        = tomoyo_path_symlink,
 259         .path_mknod          = tomoyo_path_mknod,
 260         .path_link           = tomoyo_path_link,
 261         .path_rename         = tomoyo_path_rename,
 262         .file_ioctl          = tomoyo_file_ioctl,
 263         .path_chmod          = tomoyo_path_chmod,
 264         .path_chown          = tomoyo_path_chown,
 265         .path_chroot         = tomoyo_path_chroot,
 266         .sb_mount            = tomoyo_sb_mount,
 267         .sb_umount           = tomoyo_sb_umount,
 268         .sb_pivotroot        = tomoyo_sb_pivotroot,
 269 };
 270
 271 /* Lock for GC. */
 272 struct srcu_struct tomoyo_ss;
 273
 274 static int __init tomoyo_init(void)
 275 {
 276         struct cred *cred = (struct cred *) current_cred();
 277
 278         if (!security_module_enable(&tomoyo_security_ops))
 279                 return 0;
 280         /* register ourselves with the security framework */
 281         if (register_security(&tomoyo_security_ops) ||
 282             init_srcu_struct(&tomoyo_ss))
 283                 panic("Failure registering TOMOYO Linux");
 284         printk(KERN_INFO "TOMOYO Linux initialized\n");
 285         cred->security = &tomoyo_kernel_domain;
 286         tomoyo_mm_init();
 287         return 0;
 288 }
 289
 290 security_initcall(tomoyo_init);