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
  15 static int tomoyo_cred_alloc_blank(struct cred *new, gfp_t gfp)
  16 {
  17         new->security = NULL;
  18         return 0;
  19 }
  20
  21 static int tomoyo_cred_prepare(struct cred *new, const struct cred *old,
  22                                gfp_t gfp)
  23 {
  24         struct tomoyo_domain_info *domain = old->security;
  25         new->security = domain;
  26         if (domain)
  27                 atomic_inc(&domain->users);
  28         return 0;
  29 }
  30
  31 static void tomoyo_cred_transfer(struct cred *new, const struct cred *old)
  32 {
  33         tomoyo_cred_prepare(new, old, 0);
  34 }
  35
  36 static void tomoyo_cred_free(struct cred *cred)
  37 {
  38         struct tomoyo_domain_info *domain = cred->security;
  39         if (domain)
  40                 atomic_dec(&domain->users);
  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          * Release reference to "struct tomoyo_domain_info" stored inside
  65          * "bprm->cred->security". New reference to "struct tomoyo_domain_info"
  66          * stored inside "bprm->cred->security" will be acquired later inside
  67          * tomoyo_find_next_domain().
  68          */
  69         atomic_dec(&((struct tomoyo_domain_info *)
  70                      bprm->cred->security)->users);
  71         /*
  72          * Tell tomoyo_bprm_check_security() is called for the first time of an
  73          * execve operation.
  74          */
  75         bprm->cred->security = NULL;
  76         return 0;
  77 }
  78
  79 static int tomoyo_bprm_check_security(struct linux_binprm *bprm)
  80 {
  81         struct tomoyo_domain_info *domain = bprm->cred->security;
  82
  83         /*
  84          * Execute permission is checked against pathname passed to do_execve()
  85          * using current domain.
  86          */
  87         if (!domain) {
  88                 const int idx = tomoyo_read_lock();
  89                 const int err = tomoyo_find_next_domain(bprm);
  90                 tomoyo_read_unlock(idx);
  91                 return err;
  92         }
  93         /*
  94          * Read permission is checked against interpreters using next domain.
  95          */
  96         return tomoyo_check_open_permission(domain, &bprm->file->f_path, O_RDONLY);
  97 }
  98
  99 static int tomoyo_path_truncate(struct path *path, loff_t length,
 100                                 unsigned int time_attrs)
 101 {
 102         return tomoyo_path_perm(TOMOYO_TYPE_TRUNCATE, path);
 103 }
 104
 105 static int tomoyo_path_unlink(struct path *parent, struct dentry *dentry)
 106 {
 107         struct path path = { parent->mnt, dentry };
 108         return tomoyo_path_perm(TOMOYO_TYPE_UNLINK, &path);
 109 }
 110
 111 static int tomoyo_path_mkdir(struct path *parent, struct dentry *dentry,
 112                              int mode)
 113 {
 114         struct path path = { parent->mnt, dentry };
 115         return tomoyo_path_number_perm(TOMOYO_TYPE_MKDIR, &path,
 116                                        mode & S_IALLUGO);
 117 }
 118
 119 static int tomoyo_path_rmdir(struct path *parent, struct dentry *dentry)
 120 {
 121         struct path path = { parent->mnt, dentry };
 122         return tomoyo_path_perm(TOMOYO_TYPE_RMDIR, &path);
 123 }
 124
 125 static int tomoyo_path_symlink(struct path *parent, struct dentry *dentry,
 126                                const char *old_name)
 127 {
 128         struct path path = { parent->mnt, dentry };
 129         return tomoyo_path_perm(TOMOYO_TYPE_SYMLINK, &path);
 130 }
 131
 132 static int tomoyo_path_mknod(struct path *parent, struct dentry *dentry,
 133                              int mode, unsigned int dev)
 134 {
 135         struct path path = { parent->mnt, dentry };
 136         int type = TOMOYO_TYPE_CREATE;
 137         const unsigned int perm = mode & S_IALLUGO;
 138
 139         switch (mode & S_IFMT) {
 140         case S_IFCHR:
 141                 type = TOMOYO_TYPE_MKCHAR;
 142                 break;
 143         case S_IFBLK:
 144                 type = TOMOYO_TYPE_MKBLOCK;
 145                 break;
 146         default:
 147                 goto no_dev;
 148         }
 149         return tomoyo_path_number3_perm(type, &path, perm, dev);
 150  no_dev:
 151         switch (mode & S_IFMT) {
 152         case S_IFIFO:
 153                 type = TOMOYO_TYPE_MKFIFO;
 154                 break;
 155         case S_IFSOCK:
 156                 type = TOMOYO_TYPE_MKSOCK;
 157                 break;
 158         }
 159         return tomoyo_path_number_perm(type, &path, perm);
 160 }
 161
 162 static int tomoyo_path_link(struct dentry *old_dentry, struct path *new_dir,
 163                             struct dentry *new_dentry)
 164 {
 165         struct path path1 = { new_dir->mnt, old_dentry };
 166         struct path path2 = { new_dir->mnt, new_dentry };
 167         return tomoyo_path2_perm(TOMOYO_TYPE_LINK, &path1, &path2);
 168 }
 169
 170 static int tomoyo_path_rename(struct path *old_parent,
 171                               struct dentry *old_dentry,
 172                               struct path *new_parent,
 173                               struct dentry *new_dentry)
 174 {
 175         struct path path1 = { old_parent->mnt, old_dentry };
 176         struct path path2 = { new_parent->mnt, new_dentry };
 177         return tomoyo_path2_perm(TOMOYO_TYPE_RENAME, &path1, &path2);
 178 }
 179
 180 static int tomoyo_file_fcntl(struct file *file, unsigned int cmd,
 181                              unsigned long arg)
 182 {
 183         if (cmd == F_SETFL && ((arg ^ file->f_flags) & O_APPEND))
 184                 return tomoyo_path_perm(TOMOYO_TYPE_REWRITE, &file->f_path);
 185         return 0;
 186 }
 187
 188 static int tomoyo_dentry_open(struct file *f, const struct cred *cred)
 189 {
 190         int flags = f->f_flags;
 191         /* Don't check read permission here if called from do_execve(). */
 192         if (current->in_execve)
 193                 return 0;
 194         return tomoyo_check_open_permission(tomoyo_domain(), &f->f_path, flags);
 195 }
 196
 197 static int tomoyo_file_ioctl(struct file *file, unsigned int cmd,
 198                              unsigned long arg)
 199 {
 200         return tomoyo_path_number_perm(TOMOYO_TYPE_IOCTL, &file->f_path, cmd);
 201 }
 202
 203 static int tomoyo_path_chmod(struct dentry *dentry, struct vfsmount *mnt,
 204                              mode_t mode)
 205 {
 206         struct path path = { mnt, dentry };
 207         return tomoyo_path_number_perm(TOMOYO_TYPE_CHMOD, &path,
 208                                        mode & S_IALLUGO);
 209 }
 210
 211 static int tomoyo_path_chown(struct path *path, uid_t uid, gid_t gid)
 212 {
 213         int error = 0;
 214         if (uid != (uid_t) -1)
 215                 error = tomoyo_path_number_perm(TOMOYO_TYPE_CHOWN, path, uid);
 216         if (!error && gid != (gid_t) -1)
 217                 error = tomoyo_path_number_perm(TOMOYO_TYPE_CHGRP, path, gid);
 218         return error;
 219 }
 220
 221 static int tomoyo_path_chroot(struct path *path)
 222 {
 223         return tomoyo_path_perm(TOMOYO_TYPE_CHROOT, path);
 224 }
 225
 226 static int tomoyo_sb_mount(char *dev_name, struct path *path,
 227                            char *type, unsigned long flags, void *data)
 228 {
 229         return tomoyo_mount_permission(dev_name, path, type, flags, data);
 230 }
 231
 232 static int tomoyo_sb_umount(struct vfsmount *mnt, int flags)
 233 {
 234         struct path path = { mnt, mnt->mnt_root };
 235         return tomoyo_path_perm(TOMOYO_TYPE_UMOUNT, &path);
 236 }
 237
 238 static int tomoyo_sb_pivotroot(struct path *old_path, struct path *new_path)
 239 {
 240         return tomoyo_path2_perm(TOMOYO_TYPE_PIVOT_ROOT, new_path, old_path);
 241 }
 242
 243 /*
 244  * tomoyo_security_ops is a "struct security_operations" which is used for
 245  * registering TOMOYO.
 246  */
 247 static struct security_operations tomoyo_security_ops = {
 248         .name                = "tomoyo",
 249         .cred_alloc_blank    = tomoyo_cred_alloc_blank,
 250         .cred_prepare        = tomoyo_cred_prepare,
 251         .cred_transfer       = tomoyo_cred_transfer,
 252         .cred_free           = tomoyo_cred_free,
 253         .bprm_set_creds      = tomoyo_bprm_set_creds,
 254         .bprm_check_security = tomoyo_bprm_check_security,
 255         .file_fcntl          = tomoyo_file_fcntl,
 256         .dentry_open         = tomoyo_dentry_open,
 257         .path_truncate       = tomoyo_path_truncate,
 258         .path_unlink         = tomoyo_path_unlink,
 259         .path_mkdir          = tomoyo_path_mkdir,
 260         .path_rmdir          = tomoyo_path_rmdir,
 261         .path_symlink        = tomoyo_path_symlink,
 262         .path_mknod          = tomoyo_path_mknod,
 263         .path_link           = tomoyo_path_link,
 264         .path_rename         = tomoyo_path_rename,
 265         .file_ioctl          = tomoyo_file_ioctl,
 266         .path_chmod          = tomoyo_path_chmod,
 267         .path_chown          = tomoyo_path_chown,
 268         .path_chroot         = tomoyo_path_chroot,
 269         .sb_mount            = tomoyo_sb_mount,
 270         .sb_umount           = tomoyo_sb_umount,
 271         .sb_pivotroot        = tomoyo_sb_pivotroot,
 272 };
 273
 274 /* Lock for GC. */
 275 struct srcu_struct tomoyo_ss;
 276
 277 static int __init tomoyo_init(void)
 278 {
 279         struct cred *cred = (struct cred *) current_cred();
 280
 281         if (!security_module_enable(&tomoyo_security_ops))
 282                 return 0;
 283         /* register ourselves with the security framework */
 284         if (register_security(&tomoyo_security_ops) ||
 285             init_srcu_struct(&tomoyo_ss))
 286                 panic("Failure registering TOMOYO Linux");
 287         printk(KERN_INFO "TOMOYO Linux initialized\n");
 288         cred->security = &tomoyo_kernel_domain;
 289         tomoyo_realpath_init();
 290         return 0;
 291 }
 292
 293 security_initcall(tomoyo_init);