1 /* 2 * Copyright (c) 2007 Pawel Jakub Dawidek <pjd@FreeBSD.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <sys/cdefs.h> 28 __FBSDID("$FreeBSD$"); 29 30 #include <sys/types.h> 31 #include <sys/param.h> 32 #include <sys/priv.h> 33 #include <sys/vnode.h> 34 #include <sys/mntent.h> 35 #include <sys/mount.h> 36 #include <sys/stat.h> 37 #include <sys/jail.h> 38 #include <sys/policy.h> 39 #include <sys/zfs_vfsops.h> 40 #include <sys/zfs_znode.h> 41 42 43 int 44 secpolicy_nfs(cred_t *cr) 45 { 46 47 return (spl_priv_check_cred(cr, PRIV_NFS_DAEMON)); 48 } 49 50 int 51 secpolicy_zfs(cred_t *cr) 52 { 53 54 return (spl_priv_check_cred(cr, PRIV_VFS_MOUNT)); 55 } 56 57 int 58 secpolicy_zfs_proc(cred_t *cr, proc_t *proc) 59 { 60 61 return (spl_priv_check_cred(cr, PRIV_VFS_MOUNT)); 62 } 63 64 int 65 secpolicy_sys_config(cred_t *cr, int checkonly __unused) 66 { 67 68 return (spl_priv_check_cred(cr, PRIV_ZFS_POOL_CONFIG)); 69 } 70 71 int 72 secpolicy_zinject(cred_t *cr) 73 { 74 75 return (spl_priv_check_cred(cr, PRIV_ZFS_INJECT)); 76 } 77 78 int 79 secpolicy_fs_unmount(cred_t *cr, struct mount *vfsp __unused) 80 { 81 82 return (spl_priv_check_cred(cr, PRIV_VFS_UNMOUNT)); 83 } 84 85 int 86 secpolicy_fs_owner(struct mount *mp, cred_t *cr) 87 { 88 89 if (zfs_super_owner) { 90 if (cr->cr_uid == mp->mnt_cred->cr_uid && 91 cr->cr_prison == mp->mnt_cred->cr_prison) { 92 return (0); 93 } 94 } 95 return (EPERM); 96 } 97 98 /* 99 * This check is done in kern_link(), so we could just return 0 here. 100 */ 101 extern int hardlink_check_uid; 102 int 103 secpolicy_basic_link(vnode_t *vp, cred_t *cr) 104 { 105 106 if (!hardlink_check_uid) 107 return (0); 108 if (secpolicy_fs_owner(vp->v_mount, cr) == 0) 109 return (0); 110 return (spl_priv_check_cred(cr, PRIV_VFS_LINK)); 111 } 112 113 int 114 secpolicy_vnode_stky_modify(cred_t *cr) 115 { 116 117 return (EPERM); 118 } 119 120 int 121 secpolicy_vnode_remove(vnode_t *vp, cred_t *cr) 122 { 123 124 if (secpolicy_fs_owner(vp->v_mount, cr) == 0) 125 return (0); 126 return (spl_priv_check_cred(cr, PRIV_VFS_ADMIN)); 127 } 128 129 int 130 secpolicy_vnode_access(cred_t *cr, vnode_t *vp, uid_t owner, accmode_t accmode) 131 { 132 133 if (secpolicy_fs_owner(vp->v_mount, cr) == 0) 134 return (0); 135 136 if ((accmode & VREAD) && spl_priv_check_cred(cr, PRIV_VFS_READ) != 0) 137 return (EACCES); 138 if ((accmode & VWRITE) && 139 spl_priv_check_cred(cr, PRIV_VFS_WRITE) != 0) { 140 return (EACCES); 141 } 142 if (accmode & VEXEC) { 143 if (vp->v_type == VDIR) { 144 if (spl_priv_check_cred(cr, PRIV_VFS_LOOKUP) != 0) 145 return (EACCES); 146 } else { 147 if (spl_priv_check_cred(cr, PRIV_VFS_EXEC) != 0) 148 return (EACCES); 149 } 150 } 151 return (0); 152 } 153 154 /* 155 * Like secpolicy_vnode_access() but we get the actual wanted mode and the 156 * current mode of the file, not the missing bits. 157 */ 158 int 159 secpolicy_vnode_access2(cred_t *cr, vnode_t *vp, uid_t owner, 160 accmode_t curmode, accmode_t wantmode) 161 { 162 accmode_t mode; 163 164 mode = ~curmode & wantmode; 165 166 if (mode == 0) 167 return (0); 168 169 return (secpolicy_vnode_access(cr, vp, owner, mode)); 170 } 171 172 int 173 secpolicy_vnode_any_access(cred_t *cr, vnode_t *vp, uid_t owner) 174 { 175 static int privs[] = { 176 PRIV_VFS_ADMIN, 177 PRIV_VFS_READ, 178 PRIV_VFS_WRITE, 179 PRIV_VFS_EXEC, 180 PRIV_VFS_LOOKUP 181 }; 182 int i; 183 184 if (secpolicy_fs_owner(vp->v_mount, cr) == 0) 185 return (0); 186 187 /* Same as secpolicy_vnode_setdac */ 188 if (owner == cr->cr_uid) 189 return (0); 190 191 for (i = 0; i < sizeof (privs)/sizeof (int); i++) { 192 int priv; 193 194 switch (priv = privs[i]) { 195 case PRIV_VFS_EXEC: 196 if (vp->v_type == VDIR) 197 continue; 198 break; 199 case PRIV_VFS_LOOKUP: 200 if (vp->v_type != VDIR) 201 continue; 202 break; 203 } 204 if (spl_priv_check_cred(cr, priv) == 0) 205 return (0); 206 } 207 return (EPERM); 208 } 209 210 int 211 secpolicy_vnode_setdac(vnode_t *vp, cred_t *cr, uid_t owner) 212 { 213 214 if (owner == cr->cr_uid) 215 return (0); 216 if (secpolicy_fs_owner(vp->v_mount, cr) == 0) 217 return (0); 218 return (spl_priv_check_cred(cr, PRIV_VFS_ADMIN)); 219 } 220 221 int 222 secpolicy_vnode_setattr(cred_t *cr, vnode_t *vp, struct vattr *vap, 223 const struct vattr *ovap, int flags, 224 int unlocked_access(void *, int, cred_t *), void *node) 225 { 226 int mask = vap->va_mask; 227 int error; 228 229 if (mask & AT_SIZE) { 230 if (vp->v_type == VDIR) 231 return (EISDIR); 232 error = unlocked_access(node, VWRITE, cr); 233 if (error) 234 return (error); 235 } 236 if (mask & AT_MODE) { 237 /* 238 * If not the owner of the file then check privilege 239 * for two things: the privilege to set the mode at all 240 * and, if we're setting setuid, we also need permissions 241 * to add the set-uid bit, if we're not the owner. 242 * In the specific case of creating a set-uid root 243 * file, we need even more permissions. 244 */ 245 error = secpolicy_vnode_setdac(vp, cr, ovap->va_uid); 246 if (error) 247 return (error); 248 error = secpolicy_setid_setsticky_clear(vp, vap, ovap, cr); 249 if (error) 250 return (error); 251 } else { 252 vap->va_mode = ovap->va_mode; 253 } 254 if (mask & (AT_UID | AT_GID)) { 255 error = secpolicy_vnode_setdac(vp, cr, ovap->va_uid); 256 if (error) 257 return (error); 258 259 /* 260 * To change the owner of a file, or change the group of 261 * a file to a group of which we are not a member, the 262 * caller must have privilege. 263 */ 264 if (((mask & AT_UID) && vap->va_uid != ovap->va_uid) || 265 ((mask & AT_GID) && vap->va_gid != ovap->va_gid && 266 !groupmember(vap->va_gid, cr))) { 267 if (secpolicy_fs_owner(vp->v_mount, cr) != 0) { 268 error = spl_priv_check_cred(cr, PRIV_VFS_CHOWN); 269 if (error) 270 return (error); 271 } 272 } 273 274 if (((mask & AT_UID) && vap->va_uid != ovap->va_uid) || 275 ((mask & AT_GID) && vap->va_gid != ovap->va_gid)) { 276 secpolicy_setid_clear(vap, vp, cr); 277 } 278 } 279 if (mask & (AT_ATIME | AT_MTIME)) { 280 /* 281 * From utimes(2): 282 * If times is NULL, ... The caller must be the owner of 283 * the file, have permission to write the file, or be the 284 * super-user. 285 * If times is non-NULL, ... The caller must be the owner of 286 * the file or be the super-user. 287 */ 288 error = secpolicy_vnode_setdac(vp, cr, ovap->va_uid); 289 if (error && (vap->va_vaflags & VA_UTIMES_NULL)) 290 error = unlocked_access(node, VWRITE, cr); 291 if (error) 292 return (error); 293 } 294 return (0); 295 } 296 297 int 298 secpolicy_vnode_create_gid(cred_t *cr) 299 { 300 301 return (EPERM); 302 } 303 304 int 305 secpolicy_vnode_setids_setgids(vnode_t *vp, cred_t *cr, gid_t gid) 306 { 307 308 if (groupmember(gid, cr)) 309 return (0); 310 if (secpolicy_fs_owner(vp->v_mount, cr) == 0) 311 return (0); 312 return (spl_priv_check_cred(cr, PRIV_VFS_SETGID)); 313 } 314 315 int 316 secpolicy_vnode_setid_retain(znode_t *zp, cred_t *cr, 317 boolean_t issuidroot __unused) 318 { 319 320 if (secpolicy_fs_owner(ZTOV(zp)->v_mount, cr) == 0) 321 return (0); 322 return (spl_priv_check_cred(cr, PRIV_VFS_RETAINSUGID)); 323 } 324 325 void 326 secpolicy_setid_clear(struct vattr *vap, vnode_t *vp, cred_t *cr) 327 { 328 329 if (secpolicy_fs_owner(vp->v_mount, cr) == 0) 330 return; 331 332 if ((vap->va_mode & (S_ISUID | S_ISGID)) != 0) { 333 if (spl_priv_check_cred(cr, PRIV_VFS_RETAINSUGID)) { 334 vap->va_mask |= AT_MODE; 335 vap->va_mode &= ~(S_ISUID|S_ISGID); 336 } 337 } 338 } 339 340 int 341 secpolicy_setid_setsticky_clear(vnode_t *vp, struct vattr *vap, 342 const struct vattr *ovap, cred_t *cr) 343 { 344 int error; 345 346 if (secpolicy_fs_owner(vp->v_mount, cr) == 0) 347 return (0); 348 349 /* 350 * Privileged processes may set the sticky bit on non-directories, 351 * as well as set the setgid bit on a file with a group that the process 352 * is not a member of. Both of these are allowed in jail(8). 353 */ 354 if (vp->v_type != VDIR && (vap->va_mode & S_ISTXT)) { 355 if (spl_priv_check_cred(cr, PRIV_VFS_STICKYFILE)) 356 return (EFTYPE); 357 } 358 /* 359 * Check for privilege if attempting to set the 360 * group-id bit. 361 */ 362 if ((vap->va_mode & S_ISGID) != 0) { 363 error = secpolicy_vnode_setids_setgids(vp, cr, ovap->va_gid); 364 if (error) 365 return (error); 366 } 367 /* 368 * Deny setting setuid if we are not the file owner. 369 */ 370 if ((vap->va_mode & S_ISUID) && ovap->va_uid != cr->cr_uid) { 371 error = spl_priv_check_cred(cr, PRIV_VFS_ADMIN); 372 if (error) 373 return (error); 374 } 375 return (0); 376 } 377 378 int 379 secpolicy_fs_mount(cred_t *cr, vnode_t *mvp, struct mount *vfsp) 380 { 381 382 return (spl_priv_check_cred(cr, PRIV_VFS_MOUNT)); 383 } 384 385 int 386 secpolicy_vnode_owner(vnode_t *vp, cred_t *cr, uid_t owner) 387 { 388 389 if (owner == cr->cr_uid) 390 return (0); 391 if (secpolicy_fs_owner(vp->v_mount, cr) == 0) 392 return (0); 393 394 /* XXX: vfs_suser()? */ 395 return (spl_priv_check_cred(cr, PRIV_VFS_MOUNT_OWNER)); 396 } 397 398 int 399 secpolicy_vnode_chown(vnode_t *vp, cred_t *cr, uid_t owner) 400 { 401 402 if (secpolicy_fs_owner(vp->v_mount, cr) == 0) 403 return (0); 404 return (spl_priv_check_cred(cr, PRIV_VFS_CHOWN)); 405 } 406 407 void 408 secpolicy_fs_mount_clearopts(cred_t *cr, struct mount *vfsp) 409 { 410 411 if (spl_priv_check_cred(cr, PRIV_VFS_MOUNT_NONUSER) != 0) { 412 MNT_ILOCK(vfsp); 413 vfsp->vfs_flag |= VFS_NOSETUID | MNT_USER; 414 vfs_clearmntopt(vfsp, MNTOPT_SETUID); 415 vfs_setmntopt(vfsp, MNTOPT_NOSETUID, NULL, 0); 416 MNT_IUNLOCK(vfsp); 417 } 418 } 419 420 /* 421 * Check privileges for setting xvattr attributes 422 */ 423 int 424 secpolicy_xvattr(vnode_t *vp, xvattr_t *xvap, uid_t owner, cred_t *cr, 425 vtype_t vtype) 426 { 427 428 if (secpolicy_fs_owner(vp->v_mount, cr) == 0) 429 return (0); 430 return (spl_priv_check_cred(cr, PRIV_VFS_SYSFLAGS)); 431 } 432 433 int 434 secpolicy_smb(cred_t *cr) 435 { 436 437 return (spl_priv_check_cred(cr, PRIV_NETSMB)); 438 } 439