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_prepare(struct cred *new, const struct cred *old,
  18                                gfp_t gfp)
  19 {
  20         /*
  21          * Since "struct tomoyo_domain_info *" is a sharable pointer,
  22          * we don't need to duplicate.
  23          */
  24         new->security = old->security;
  25         return 0;
  26 }
  27
  28 static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
  29 {
  30         /*
  31          * Do only if this function is called for the first time of an execve
  32          * operation.
  33          */
  34         if (bprm->cred_prepared)
  35                 return 0;
  36         /*
  37          * Load policy if /sbin/tomoyo-init exists and /sbin/init is requested
  38          * for the first time.
  39          */
  40         if (!tomoyo_policy_loaded)
  41                 tomoyo_load_policy(bprm->filename);
  42         /*
  43          * Tell tomoyo_bprm_check_security() is called for the first time of an
  44          * execve operation.
  45          */
  46         bprm->cred->security = NULL;
  47         return 0;
  48 }
  49
  50 static int tomoyo_bprm_check_security(struct linux_binprm *bprm)
  51 {
  52         struct tomoyo_domain_info *domain = bprm->cred->security;
  53
  54         /*
  55          * Execute permission is checked against pathname passed to do_execve()
  56          * using current domain.
  57          */
  58         if (!domain) {
  59                 struct tomoyo_domain_info *next_domain = NULL;
  60                 int retval = tomoyo_find_next_domain(bprm, &next_domain);
  61
  62                 if (!retval)
  63                         bprm->cred->security = next_domain;
  64                 return retval;
  65         }
  66         /*
  67          * Read permission is checked against interpreters using next domain.
  68          * '1' is the result of open_to_namei_flags(O_RDONLY).
  69          */
  70         return tomoyo_check_open_permission(domain, &bprm->file->f_path, 1);
  71 }
  72
  73 #ifdef CONFIG_SYSCTL
  74
  75 static int tomoyo_prepend(char **buffer, int *buflen, const char *str)
  76 {
  77         int namelen = strlen(str);
  78
  79         if (*buflen < namelen)
  80                 return -ENOMEM;
  81         *buflen -= namelen;
  82         *buffer -= namelen;
  83         memcpy(*buffer, str, namelen);
  84         return 0;
  85 }
  86
  87 /**
  88  * tomoyo_sysctl_path - return the realpath of a ctl_table.
  89  * @table: pointer to "struct ctl_table".
  90  *
  91  * Returns realpath(3) of the @table on success.
  92  * Returns NULL on failure.
  93  *
  94  * This function uses tomoyo_alloc(), so the caller must call tomoyo_free()
  95  * if this function didn't return NULL.
  96  */
  97 static char *tomoyo_sysctl_path(struct ctl_table *table)
  98 {
  99         int buflen = TOMOYO_MAX_PATHNAME_LEN;
 100         char *buf = tomoyo_alloc(buflen);
 101         char *end = buf + buflen;
 102         int error = -ENOMEM;
 103
 104         if (!buf)
 105                 return NULL;
 106
 107         *--end = '\0';
 108         buflen--;
 109         while (table) {
 110                 char num[32];
 111                 const char *sp = table->procname;
 112
 113                 if (!sp) {
 114                         memset(num, 0, sizeof(num));
 115                         snprintf(num, sizeof(num) - 1, "=%d=", table->ctl_name);
 116                         sp = num;
 117                 }
 118                 if (tomoyo_prepend(&end, &buflen, sp) ||
 119                     tomoyo_prepend(&end, &buflen, "/"))
 120                         goto out;
 121                 table = table->parent;
 122         }
 123         if (tomoyo_prepend(&end, &buflen, "/proc/sys"))
 124                 goto out;
 125         error = tomoyo_encode(buf, end - buf, end);
 126  out:
 127         if (!error)
 128                 return buf;
 129         tomoyo_free(buf);
 130         return NULL;
 131 }
 132
 133 static int tomoyo_sysctl(struct ctl_table *table, int op)
 134 {
 135         int error;
 136         char *name;
 137
 138         op &= MAY_READ | MAY_WRITE;
 139         if (!op)
 140                 return 0;
 141         name = tomoyo_sysctl_path(table);
 142         if (!name)
 143                 return -ENOMEM;
 144         error = tomoyo_check_file_perm(tomoyo_domain(), name, op);
 145         tomoyo_free(name);
 146         return error;
 147 }
 148 #endif
 149
 150 static int tomoyo_path_truncate(struct path *path, loff_t length,
 151                                 unsigned int time_attrs)
 152 {
 153         return tomoyo_check_1path_perm(tomoyo_domain(),
 154                                        TOMOYO_TYPE_TRUNCATE_ACL,
 155                                        path);
 156 }
 157
 158 static int tomoyo_path_unlink(struct path *parent, struct dentry *dentry)
 159 {
 160         struct path path = { parent->mnt, dentry };
 161         return tomoyo_check_1path_perm(tomoyo_domain(),
 162                                        TOMOYO_TYPE_UNLINK_ACL,
 163                                        &path);
 164 }
 165
 166 static int tomoyo_path_mkdir(struct path *parent, struct dentry *dentry,
 167                              int mode)
 168 {
 169         struct path path = { parent->mnt, dentry };
 170         return tomoyo_check_1path_perm(tomoyo_domain(),
 171                                        TOMOYO_TYPE_MKDIR_ACL,
 172                                        &path);
 173 }
 174
 175 static int tomoyo_path_rmdir(struct path *parent, struct dentry *dentry)
 176 {
 177         struct path path = { parent->mnt, dentry };
 178         return tomoyo_check_1path_perm(tomoyo_domain(),
 179                                        TOMOYO_TYPE_RMDIR_ACL,
 180                                        &path);
 181 }
 182
 183 static int tomoyo_path_symlink(struct path *parent, struct dentry *dentry,
 184                                const char *old_name)
 185 {
 186         struct path path = { parent->mnt, dentry };
 187         return tomoyo_check_1path_perm(tomoyo_domain(),
 188                                        TOMOYO_TYPE_SYMLINK_ACL,
 189                                        &path);
 190 }
 191
 192 static int tomoyo_path_mknod(struct path *parent, struct dentry *dentry,
 193                              int mode, unsigned int dev)
 194 {
 195         struct path path = { parent->mnt, dentry };
 196         int type = TOMOYO_TYPE_CREATE_ACL;
 197
 198         switch (mode & S_IFMT) {
 199         case S_IFCHR:
 200                 type = TOMOYO_TYPE_MKCHAR_ACL;
 201                 break;
 202         case S_IFBLK:
 203                 type = TOMOYO_TYPE_MKBLOCK_ACL;
 204                 break;
 205         case S_IFIFO:
 206                 type = TOMOYO_TYPE_MKFIFO_ACL;
 207                 break;
 208         case S_IFSOCK:
 209                 type = TOMOYO_TYPE_MKSOCK_ACL;
 210                 break;
 211         }
 212         return tomoyo_check_1path_perm(tomoyo_domain(),
 213                                        type, &path);
 214 }
 215
 216 static int tomoyo_path_link(struct dentry *old_dentry, struct path *new_dir,
 217                             struct dentry *new_dentry)
 218 {
 219         struct path path1 = { new_dir->mnt, old_dentry };
 220         struct path path2 = { new_dir->mnt, new_dentry };
 221         return tomoyo_check_2path_perm(tomoyo_domain(),
 222                                        TOMOYO_TYPE_LINK_ACL,
 223                                        &path1, &path2);
 224 }
 225
 226 static int tomoyo_path_rename(struct path *old_parent,
 227                               struct dentry *old_dentry,
 228                               struct path *new_parent,
 229                               struct dentry *new_dentry)
 230 {
 231         struct path path1 = { old_parent->mnt, old_dentry };
 232         struct path path2 = { new_parent->mnt, new_dentry };
 233         return tomoyo_check_2path_perm(tomoyo_domain(),
 234                                        TOMOYO_TYPE_RENAME_ACL,
 235                                        &path1, &path2);
 236 }
 237
 238 static int tomoyo_file_fcntl(struct file *file, unsigned int cmd,
 239                              unsigned long arg)
 240 {
 241         if (cmd == F_SETFL && ((arg ^ file->f_flags) & O_APPEND))
 242                 return tomoyo_check_rewrite_permission(tomoyo_domain(), file);
 243         return 0;
 244 }
 245
 246 static int tomoyo_dentry_open(struct file *f, const struct cred *cred)
 247 {
 248         int flags = f->f_flags;
 249
 250         if ((flags + 1) & O_ACCMODE)
 251                 flags++;
 252         flags |= f->f_flags & (O_APPEND | O_TRUNC);
 253         /* Don't check read permission here if called from do_execve(). */
 254         if (current->in_execve)
 255                 return 0;
 256         return tomoyo_check_open_permission(tomoyo_domain(), &f->f_path, flags);
 257 }
 258
 259 static struct security_operations tomoyo_security_ops = {
 260         .name                = "tomoyo",
 261         .cred_prepare        = tomoyo_cred_prepare,
 262         .bprm_set_creds      = tomoyo_bprm_set_creds,
 263         .bprm_check_security = tomoyo_bprm_check_security,
 264 #ifdef CONFIG_SYSCTL
 265         .sysctl              = tomoyo_sysctl,
 266 #endif
 267         .file_fcntl          = tomoyo_file_fcntl,
 268         .dentry_open         = tomoyo_dentry_open,
 269         .path_truncate       = tomoyo_path_truncate,
 270         .path_unlink         = tomoyo_path_unlink,
 271         .path_mkdir          = tomoyo_path_mkdir,
 272         .path_rmdir          = tomoyo_path_rmdir,
 273         .path_symlink        = tomoyo_path_symlink,
 274         .path_mknod          = tomoyo_path_mknod,
 275         .path_link           = tomoyo_path_link,
 276         .path_rename         = tomoyo_path_rename,
 277 };
 278
 279 static int __init tomoyo_init(void)
 280 {
 281         struct cred *cred = (struct cred *) current_cred();
 282
 283         if (!security_module_enable(&tomoyo_security_ops))
 284                 return 0;
 285         /* register ourselves with the security framework */
 286         if (register_security(&tomoyo_security_ops))
 287                 panic("Failure registering TOMOYO Linux");
 288         printk(KERN_INFO "TOMOYO Linux initialized\n");
 289         cred->security = &tomoyo_kernel_domain;
 290         tomoyo_realpath_init();
 291         return 0;
 292 }
 293
 294 security_initcall(tomoyo_init);