1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved. 24 * Copyright 2013, Joyent, Inc. All rights reserved. 25 * Copyright (C) 2016 Lawrence Livermore National Security, LLC. 26 * 27 * For Linux the vast majority of this enforcement is already handled via 28 * the standard Linux VFS permission checks. However certain administrative 29 * commands which bypass the standard mechanisms may need to make use of 30 * this functionality. 31 */ 32 33 #include <sys/policy.h> 34 #include <linux/security.h> 35 #include <linux/vfs_compat.h> 36 37 /* 38 * The passed credentials cannot be directly verified because Linux only 39 * provides and interface to check the *current* process credentials. In 40 * order to handle this the capable() test is only run when the passed 41 * credentials match the current process credentials or the kcred. In 42 * all other cases this function must fail and return the passed err. 43 */ 44 static int 45 priv_policy_ns(const cred_t *cr, int capability, int err, 46 struct user_namespace *ns) 47 { 48 if (cr != CRED() && (cr != kcred)) 49 return (err); 50 51 #if defined(CONFIG_USER_NS) 52 if (!(ns ? ns_capable(ns, capability) : capable(capability))) 53 #else 54 if (!capable(capability)) 55 #endif 56 return (err); 57 58 return (0); 59 } 60 61 static int 62 priv_policy(const cred_t *cr, int capability, int err) 63 { 64 return (priv_policy_ns(cr, capability, err, NULL)); 65 } 66 67 static int 68 priv_policy_user(const cred_t *cr, int capability, int err) 69 { 70 /* 71 * All priv_policy_user checks are preceded by kuid/kgid_has_mapping() 72 * checks. If we cannot do them, we shouldn't be using ns_capable() 73 * since we don't know whether the affected files are valid in our 74 * namespace. 75 */ 76 #if defined(CONFIG_USER_NS) 77 return (priv_policy_ns(cr, capability, err, cr->user_ns)); 78 #else 79 return (priv_policy_ns(cr, capability, err, NULL)); 80 #endif 81 } 82 83 /* 84 * Checks for operations that are either client-only or are used by 85 * both clients and servers. 86 */ 87 int 88 secpolicy_nfs(const cred_t *cr) 89 { 90 return (priv_policy(cr, CAP_SYS_ADMIN, EPERM)); 91 } 92 93 /* 94 * Catch all system configuration. 95 */ 96 int 97 secpolicy_sys_config(const cred_t *cr, boolean_t checkonly) 98 { 99 return (priv_policy(cr, CAP_SYS_ADMIN, EPERM)); 100 } 101 102 /* 103 * Like secpolicy_vnode_access() but we get the actual wanted mode and the 104 * current mode of the file, not the missing bits. 105 * 106 * Enforced in the Linux VFS. 107 */ 108 int 109 secpolicy_vnode_access2(const cred_t *cr, struct inode *ip, uid_t owner, 110 mode_t curmode, mode_t wantmode) 111 { 112 return (0); 113 } 114 115 /* 116 * This is a special routine for ZFS; it is used to determine whether 117 * any of the privileges in effect allow any form of access to the 118 * file. There's no reason to audit this or any reason to record 119 * this. More work is needed to do the "KPLD" stuff. 120 */ 121 int 122 secpolicy_vnode_any_access(const cred_t *cr, struct inode *ip, uid_t owner) 123 { 124 if (crgetfsuid(cr) == owner) 125 return (0); 126 127 if (inode_owner_or_capable(ip)) 128 return (0); 129 130 #if defined(CONFIG_USER_NS) 131 if (!kuid_has_mapping(cr->user_ns, SUID_TO_KUID(owner))) 132 return (EPERM); 133 #endif 134 135 if (priv_policy_user(cr, CAP_DAC_OVERRIDE, EPERM) == 0) 136 return (0); 137 138 if (priv_policy_user(cr, CAP_DAC_READ_SEARCH, EPERM) == 0) 139 return (0); 140 141 return (EPERM); 142 } 143 144 /* 145 * Determine if subject can chown owner of a file. 146 */ 147 int 148 secpolicy_vnode_chown(const cred_t *cr, uid_t owner) 149 { 150 if (crgetfsuid(cr) == owner) 151 return (0); 152 153 #if defined(CONFIG_USER_NS) 154 if (!kuid_has_mapping(cr->user_ns, SUID_TO_KUID(owner))) 155 return (EPERM); 156 #endif 157 158 return (priv_policy_user(cr, CAP_FOWNER, EPERM)); 159 } 160 161 /* 162 * Determine if subject can change group ownership of a file. 163 */ 164 int 165 secpolicy_vnode_create_gid(const cred_t *cr) 166 { 167 return (priv_policy(cr, CAP_SETGID, EPERM)); 168 } 169 170 /* 171 * Policy determines whether we can remove an entry from a directory, 172 * regardless of permission bits. 173 */ 174 int 175 secpolicy_vnode_remove(const cred_t *cr) 176 { 177 return (priv_policy(cr, CAP_FOWNER, EPERM)); 178 } 179 180 /* 181 * Determine that subject can modify the mode of a file. allzone privilege 182 * needed when modifying root owned object. 183 */ 184 int 185 secpolicy_vnode_setdac(const cred_t *cr, uid_t owner) 186 { 187 if (crgetfsuid(cr) == owner) 188 return (0); 189 190 #if defined(CONFIG_USER_NS) 191 if (!kuid_has_mapping(cr->user_ns, SUID_TO_KUID(owner))) 192 return (EPERM); 193 #endif 194 195 return (priv_policy_user(cr, CAP_FOWNER, EPERM)); 196 } 197 198 /* 199 * Are we allowed to retain the set-uid/set-gid bits when 200 * changing ownership or when writing to a file? 201 * "issuid" should be true when set-uid; only in that case 202 * root ownership is checked (setgid is assumed). 203 * 204 * Enforced in the Linux VFS. 205 */ 206 int 207 secpolicy_vnode_setid_retain(const cred_t *cr, boolean_t issuidroot) 208 { 209 return (priv_policy_user(cr, CAP_FSETID, EPERM)); 210 } 211 212 /* 213 * Determine that subject can set the file setgid flag. 214 */ 215 int 216 secpolicy_vnode_setids_setgids(const cred_t *cr, gid_t gid) 217 { 218 #if defined(CONFIG_USER_NS) 219 if (!kgid_has_mapping(cr->user_ns, SGID_TO_KGID(gid))) 220 return (EPERM); 221 #endif 222 if (crgetfsgid(cr) != gid && !groupmember(gid, cr)) 223 return (priv_policy_user(cr, CAP_FSETID, EPERM)); 224 225 return (0); 226 } 227 228 /* 229 * Determine if the subject can inject faults in the ZFS fault injection 230 * framework. Requires all privileges. 231 */ 232 int 233 secpolicy_zinject(const cred_t *cr) 234 { 235 return (priv_policy(cr, CAP_SYS_ADMIN, EACCES)); 236 } 237 238 /* 239 * Determine if the subject has permission to manipulate ZFS datasets 240 * (not pools). Equivalent to the SYS_MOUNT privilege. 241 */ 242 int 243 secpolicy_zfs(const cred_t *cr) 244 { 245 return (priv_policy(cr, CAP_SYS_ADMIN, EACCES)); 246 } 247 248 /* 249 * Equivalent to secpolicy_zfs(), but works even if the cred_t is not that of 250 * the current process. Takes both cred_t and proc_t so that this can work 251 * easily on all platforms. 252 * 253 * The has_capability() function was first exported in the 4.10 Linux kernel 254 * then backported to some LTS kernels. Prior to this change there was no 255 * mechanism to perform this check therefore EACCES is returned when the 256 * functionality is not present in the kernel. 257 */ 258 int 259 secpolicy_zfs_proc(const cred_t *cr, proc_t *proc) 260 { 261 #if defined(HAVE_HAS_CAPABILITY) 262 if (!has_capability(proc, CAP_SYS_ADMIN)) 263 return (EACCES); 264 return (0); 265 #else 266 return (EACCES); 267 #endif 268 } 269 270 void 271 secpolicy_setid_clear(vattr_t *vap, cred_t *cr) 272 { 273 if ((vap->va_mode & (S_ISUID | S_ISGID)) != 0 && 274 secpolicy_vnode_setid_retain(cr, 275 (vap->va_mode & S_ISUID) != 0 && 276 (vap->va_mask & AT_UID) != 0 && vap->va_uid == 0) != 0) { 277 vap->va_mask |= AT_MODE; 278 vap->va_mode &= ~(S_ISUID|S_ISGID); 279 } 280 } 281 282 /* 283 * Determine that subject can set the file setid flags. 284 */ 285 static int 286 secpolicy_vnode_setid_modify(const cred_t *cr, uid_t owner) 287 { 288 if (crgetfsuid(cr) == owner) 289 return (0); 290 291 #if defined(CONFIG_USER_NS) 292 if (!kuid_has_mapping(cr->user_ns, SUID_TO_KUID(owner))) 293 return (EPERM); 294 #endif 295 296 return (priv_policy_user(cr, CAP_FSETID, EPERM)); 297 } 298 299 /* 300 * Determine that subject can make a file a "sticky". 301 * 302 * Enforced in the Linux VFS. 303 */ 304 static int 305 secpolicy_vnode_stky_modify(const cred_t *cr) 306 { 307 return (0); 308 } 309 310 int 311 secpolicy_setid_setsticky_clear(struct inode *ip, vattr_t *vap, 312 const vattr_t *ovap, cred_t *cr) 313 { 314 int error; 315 316 if ((vap->va_mode & S_ISUID) != 0 && 317 (error = secpolicy_vnode_setid_modify(cr, 318 ovap->va_uid)) != 0) { 319 return (error); 320 } 321 322 /* 323 * Check privilege if attempting to set the 324 * sticky bit on a non-directory. 325 */ 326 if (!S_ISDIR(ip->i_mode) && (vap->va_mode & S_ISVTX) != 0 && 327 secpolicy_vnode_stky_modify(cr) != 0) { 328 vap->va_mode &= ~S_ISVTX; 329 } 330 331 /* 332 * Check for privilege if attempting to set the 333 * group-id bit. 334 */ 335 if ((vap->va_mode & S_ISGID) != 0 && 336 secpolicy_vnode_setids_setgids(cr, ovap->va_gid) != 0) { 337 vap->va_mode &= ~S_ISGID; 338 } 339 340 return (0); 341 } 342 343 /* 344 * Check privileges for setting xvattr attributes 345 */ 346 int 347 secpolicy_xvattr(xvattr_t *xvap, uid_t owner, cred_t *cr, mode_t type) 348 { 349 return (secpolicy_vnode_chown(cr, owner)); 350 } 351 352 /* 353 * Check privileges for setattr attributes. 354 * 355 * Enforced in the Linux VFS. 356 */ 357 int 358 secpolicy_vnode_setattr(cred_t *cr, struct inode *ip, struct vattr *vap, 359 const struct vattr *ovap, int flags, 360 int unlocked_access(void *, int, cred_t *), void *node) 361 { 362 return (0); 363 } 364 365 /* 366 * Check privileges for links. 367 * 368 * Enforced in the Linux VFS. 369 */ 370 int 371 secpolicy_basic_link(const cred_t *cr) 372 { 373 return (0); 374 } 375