1 /* $NetBSD: compat_util.c,v 1.29 2005/05/29 22:08:16 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 1994 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Christos Zoulas and Frank van der Linden. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 __KERNEL_RCSID(0, "$NetBSD: compat_util.c,v 1.29 2005/05/29 22:08:16 christos Exp $"); 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/namei.h> 45 #include <sys/proc.h> 46 #include <sys/file.h> 47 #include <sys/stat.h> 48 #include <sys/filedesc.h> 49 #include <sys/exec.h> 50 #include <sys/ioctl.h> 51 #include <sys/kernel.h> 52 #include <sys/malloc.h> 53 #include <sys/vnode.h> 54 #include <sys/syslog.h> 55 #include <sys/mount.h> 56 57 58 #include <compat/common/compat_util.h> 59 60 /* 61 * Search an alternate path before passing pathname arguments on 62 * to system calls. Useful for keeping a separate 'emulation tree'. 63 * 64 * According to sflag, we either check for existance of the file or if 65 * it can be created or if the file is symlink. 66 * 67 * In case of success, emul_find returns 0: 68 * If sgp is provided, the path is in user space, and pbuf gets 69 * allocated in user space (in the stackgap). Otherwise the path 70 * is already in kernel space and a kernel buffer gets allocated 71 * and returned in pbuf, that must be freed by the user. 72 * In case of error, the error number is returned and *pbuf = path. 73 */ 74 int 75 emul_find(p, sgp, prefix, path, pbuf, sflag) 76 struct proc *p; 77 caddr_t *sgp; /* Pointer to stackgap memory */ 78 const char *prefix; 79 const char *path; 80 const char **pbuf; 81 int sflag; 82 { 83 struct nameidata nd; 84 struct nameidata ndroot; 85 struct vattr vat; 86 struct vattr vatroot; 87 int error; 88 char *ptr, *tbuf, *cp; 89 const char *pr; 90 size_t sz, len; 91 92 tbuf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 93 *pbuf = path; 94 95 for (ptr = tbuf, pr = prefix; (*ptr = *pr) != '\0'; ptr++, pr++) 96 continue; 97 98 sz = MAXPATHLEN - (ptr - tbuf); 99 100 /* 101 * If sgp is not given then the path is already in kernel space 102 */ 103 if (sgp == NULL) 104 error = copystr(path, ptr, sz, &len); 105 else 106 error = copyinstr(path, ptr, sz, &len); 107 108 if (error) 109 goto bad; 110 111 if (*ptr != '/') { 112 error = EINVAL; 113 goto bad; 114 } 115 116 /* 117 * We provide an escape method, so that the user can 118 * always specify the real root. If the path is prefixed 119 * by /../ we kill the alternate search 120 */ 121 if (ptr[1] == '.' && ptr[2] == '.' && ptr[3] == '/') { 122 len -= 3; 123 (void)memcpy(tbuf, &ptr[3], len); 124 ptr = tbuf; 125 goto good; 126 } 127 128 /* 129 * We know that there is a / somewhere in this pathname. 130 * Search backwards for it, to find the file's parent dir 131 * to see if it exists in the alternate tree. If it does, 132 * and we want to create a file (sflag is set). We don't 133 * need to worry about the root comparison in this case. 134 */ 135 136 switch (sflag) { 137 case CHECK_ALT_FL_CREAT: 138 for (cp = &ptr[len] - 1; *cp != '/'; cp--) 139 ; 140 *cp = '\0'; 141 142 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, tbuf, p); 143 144 if ((error = namei(&nd)) != 0) 145 goto bad; 146 147 *cp = '/'; 148 break; 149 case CHECK_ALT_FL_EXISTS: 150 case CHECK_ALT_FL_SYMLINK: 151 NDINIT(&nd, LOOKUP, 152 (sflag == CHECK_ALT_FL_SYMLINK) ? NOFOLLOW : FOLLOW, 153 UIO_SYSSPACE, tbuf, p); 154 155 if ((error = namei(&nd)) != 0) 156 goto bad; 157 158 /* 159 * We now compare the vnode of the emulation root to the one 160 * vnode asked. If they resolve to be the same, then we 161 * ignore the match so that the real root gets used. 162 * This avoids the problem of traversing "../.." to find the 163 * root directory and never finding it, because "/" resolves 164 * to the emulation root directory. This is expensive :-( 165 */ 166 NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, prefix, p); 167 168 if ((error = namei(&ndroot)) != 0) 169 goto bad2; 170 171 if ((error = VOP_GETATTR(nd.ni_vp, &vat, p->p_ucred, p)) != 0) 172 goto bad3; 173 174 if ((error = VOP_GETATTR(ndroot.ni_vp, &vatroot, p->p_ucred, p)) 175 != 0) 176 goto bad3; 177 178 if (vat.va_fsid == vatroot.va_fsid && 179 vat.va_fileid == vatroot.va_fileid) { 180 error = ENOENT; 181 goto bad3; 182 } 183 184 break; 185 } 186 187 vrele(nd.ni_vp); 188 if (sflag == CHECK_ALT_FL_EXISTS) 189 vrele(ndroot.ni_vp); 190 191 good: 192 if (sgp == NULL) 193 *pbuf = tbuf; 194 else { 195 sz = &ptr[len] - tbuf; 196 *pbuf = stackgap_alloc(p, sgp, sz + 1); 197 if (*pbuf == NULL) { 198 error = ENAMETOOLONG; 199 goto bad; 200 } 201 /*XXXUNCONST*/ 202 if ((error = copyout(tbuf, __UNCONST(*pbuf), sz)) != 0) { 203 *pbuf = path; 204 goto bad; 205 } 206 free(tbuf, M_TEMP); 207 } 208 return 0; 209 210 bad3: 211 vrele(ndroot.ni_vp); 212 bad2: 213 vrele(nd.ni_vp); 214 bad: 215 free(tbuf, M_TEMP); 216 return error; 217 } 218 219 /* 220 * Search the alternate path for dynamic binary interpreter. If not found 221 * there, check if the interpreter exists in within 'proper' tree. 222 */ 223 int 224 emul_find_interp(struct proc *p, const char *prefix, char *itp) 225 { 226 const char *bp; 227 int error; 228 229 if (emul_find(p, NULL, prefix, itp, &bp, CHECK_ALT_FL_EXISTS) == 0) { 230 size_t len; 231 232 if ((error = copystr(bp, itp, MAXPATHLEN, &len))) 233 return error; 234 /*XXXUNCONST*/ 235 free(__UNCONST(bp), M_TEMP); 236 } else { 237 /* check filename without the emul prefix */ 238 struct nameidata nd; 239 240 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, itp, p); 241 242 if ((error = namei(&nd))) 243 return error; 244 245 vrele(nd.ni_vp); 246 } 247 248 return (0); 249 } 250 251 /* 252 * Translate one set of flags to another, based on the entries in 253 * the given table. If 'leftover' is specified, it is filled in 254 * with any flags which could not be translated. 255 */ 256 unsigned long 257 emul_flags_translate(const struct emul_flags_xtab *tab, 258 unsigned long in, unsigned long *leftover) 259 { 260 unsigned long out; 261 262 for (out = 0; tab->omask != 0; tab++) { 263 if ((in & tab->omask) == tab->oval) { 264 in &= ~tab->omask; 265 out |= tab->nval; 266 } 267 } 268 if (leftover != NULL) 269 *leftover = in; 270 return (out); 271 } 272 273 caddr_t 274 stackgap_init(p, sz) 275 const struct proc *p; 276 size_t sz; 277 { 278 if (sz == 0) 279 sz = STACKGAPLEN; 280 if (sz > STACKGAPLEN) 281 panic("size %lu > STACKGAPLEN", (unsigned long)sz); 282 #define szsigcode ((caddr_t)(p->p_emul->e_esigcode - p->p_emul->e_sigcode)) 283 return (caddr_t)(((unsigned long)p->p_psstr - (unsigned long)szsigcode 284 - sz) & ~ALIGNBYTES); 285 #undef szsigcode 286 } 287 288 289 void * 290 stackgap_alloc(p, sgp, sz) 291 const struct proc *p; 292 caddr_t *sgp; 293 size_t sz; 294 { 295 void *n = (void *) *sgp; 296 caddr_t nsgp; 297 const struct emul *e = p->p_emul; 298 int sigsize = e->e_esigcode - e->e_sigcode; 299 300 sz = ALIGN(sz); 301 nsgp = *sgp + sz; 302 if (nsgp > (((caddr_t)p->p_psstr) - sigsize)) 303 return NULL; 304 *sgp = nsgp; 305 return n; 306 } 307 308 void 309 compat_offseterr(vp, msg) 310 struct vnode *vp; 311 const char *msg; 312 { 313 struct mount *mp; 314 315 mp = vp->v_mount; 316 317 log(LOG_ERR, "%s: dir offset too large on fs %s (mounted from %s)\n", 318 msg, mp->mnt_stat.f_mntonname, mp->mnt_stat.f_mntfromname); 319 uprintf("%s: dir offset too large for emulated program\n", msg); 320 } 321