exec_script.c revision 1.22.2.1
1 /* $NetBSD: exec_script.c,v 1.22.2.1 2000/11/20 18:08:55 bouyer Exp $ */ 2 3 /* 4 * Copyright (c) 1993, 1994, 1996 Christopher G. Demetriou 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by Christopher G. Demetriou. 18 * 4. The name of the author may not be used to endorse or promote products 19 * derived from this software without specific prior written permission 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 #if defined(SETUIDSCRIPTS) && !defined(FDSCRIPTS) 34 #define FDSCRIPTS /* Need this for safe set-id scripts. */ 35 #endif 36 37 #include <sys/param.h> 38 #include <sys/systm.h> 39 #include <sys/proc.h> 40 #include <sys/malloc.h> 41 #include <sys/vnode.h> 42 #include <sys/namei.h> 43 #include <sys/file.h> 44 #ifdef SETUIDSCRIPTS 45 #include <sys/stat.h> 46 #endif 47 #include <sys/filedesc.h> 48 #include <sys/exec.h> 49 #include <sys/resourcevar.h> 50 51 #include <sys/exec_script.h> 52 53 /* 54 * exec_script_makecmds(): Check if it's an executable shell script. 55 * 56 * Given a proc pointer and an exec package pointer, see if the referent 57 * of the epp is in shell script. If it is, then set thing up so that 58 * the script can be run. This involves preparing the address space 59 * and arguments for the shell which will run the script. 60 * 61 * This function is ultimately responsible for creating a set of vmcmds 62 * which can be used to build the process's vm space and inserting them 63 * into the exec package. 64 */ 65 int 66 exec_script_makecmds(struct proc *p, struct exec_package *epp) 67 { 68 int error, hdrlinelen, shellnamelen, shellarglen; 69 char *hdrstr = epp->ep_hdr; 70 char *cp, *shellname, *shellarg, *oldpnbuf; 71 char **shellargp, **tmpsap; 72 struct vnode *scriptvp; 73 #ifdef SETUIDSCRIPTS 74 /* Gcc needs those initialized for spurious uninitialized warning */ 75 uid_t script_uid = (uid_t) -1; 76 gid_t script_gid = NOGROUP; 77 u_short script_sbits; 78 #endif 79 80 /* 81 * if the magic isn't that of a shell script, or we've already 82 * done shell script processing for this exec, punt on it. 83 */ 84 if ((epp->ep_flags & EXEC_INDIR) != 0 || 85 epp->ep_hdrvalid < EXEC_SCRIPT_MAGICLEN || 86 strncmp(hdrstr, EXEC_SCRIPT_MAGIC, EXEC_SCRIPT_MAGICLEN)) 87 return ENOEXEC; 88 89 /* 90 * check that the shell spec is terminated by a newline, 91 * and that it isn't too large. Don't modify the 92 * buffer unless we're ready to commit to handling it. 93 * (The latter requirement means that we have to check 94 * for both spaces and tabs later on.) 95 */ 96 hdrlinelen = min(epp->ep_hdrvalid, MAXINTERP); 97 for (cp = hdrstr + EXEC_SCRIPT_MAGICLEN; cp < hdrstr + hdrlinelen; 98 cp++) { 99 if (*cp == '\n') { 100 *cp = '\0'; 101 break; 102 } 103 } 104 if (cp >= hdrstr + hdrlinelen) 105 return ENOEXEC; 106 107 shellname = NULL; 108 shellarg = NULL; 109 shellarglen = 0; 110 111 /* strip spaces before the shell name */ 112 for (cp = hdrstr + EXEC_SCRIPT_MAGICLEN; *cp == ' ' || *cp == '\t'; 113 cp++) 114 ; 115 116 /* collect the shell name; remember it's length for later */ 117 shellname = cp; 118 shellnamelen = 0; 119 if (*cp == '\0') 120 goto check_shell; 121 for ( /* cp = cp */ ; *cp != '\0' && *cp != ' ' && *cp != '\t'; cp++) 122 shellnamelen++; 123 if (*cp == '\0') 124 goto check_shell; 125 *cp++ = '\0'; 126 127 /* skip spaces before any argument */ 128 for ( /* cp = cp */ ; *cp == ' ' || *cp == '\t'; cp++) 129 ; 130 if (*cp == '\0') 131 goto check_shell; 132 133 /* 134 * collect the shell argument. everything after the shell name 135 * is passed as ONE argument; that's the correct (historical) 136 * behaviour. 137 */ 138 shellarg = cp; 139 for ( /* cp = cp */ ; *cp != '\0'; cp++) 140 shellarglen++; 141 *cp++ = '\0'; 142 143 check_shell: 144 #ifdef SETUIDSCRIPTS 145 /* 146 * MNT_NOSUID and STRC are already taken care of by check_exec, 147 * so we don't need to worry about them now or later. 148 */ 149 script_sbits = epp->ep_vap->va_mode & (S_ISUID | S_ISGID); 150 if (script_sbits != 0) { 151 script_uid = epp->ep_vap->va_uid; 152 script_gid = epp->ep_vap->va_gid; 153 } 154 #endif 155 #ifdef FDSCRIPTS 156 /* 157 * if the script isn't readable, or it's set-id, then we've 158 * gotta supply a "/dev/fd/..." for the shell to read. 159 * Note that stupid shells (csh) do the wrong thing, and 160 * close all open fd's when the start. That kills this 161 * method of implementing "safe" set-id and x-only scripts. 162 */ 163 vn_lock(epp->ep_vp, LK_EXCLUSIVE | LK_RETRY); 164 error = VOP_ACCESS(epp->ep_vp, VREAD, p->p_ucred, p); 165 VOP_UNLOCK(epp->ep_vp, 0); 166 if (error == EACCES 167 #ifdef SETUIDSCRIPTS 168 || script_sbits 169 #endif 170 ) { 171 struct file *fp; 172 173 #if defined(DIAGNOSTIC) && defined(FDSCRIPTS) 174 if (epp->ep_flags & EXEC_HASFD) 175 panic("exec_script_makecmds: epp already has a fd"); 176 #endif 177 178 /* falloc() will use the descriptor for us */ 179 if ((error = falloc(p, &fp, &epp->ep_fd)) != 0) { 180 scriptvp = NULL; 181 shellargp = NULL; 182 goto fail; 183 } 184 185 epp->ep_flags |= EXEC_HASFD; 186 fp->f_type = DTYPE_VNODE; 187 fp->f_ops = &vnops; 188 fp->f_data = (caddr_t) epp->ep_vp; 189 fp->f_flag = FREAD; 190 FILE_UNUSE(fp, p); 191 } 192 #endif 193 194 /* set up the parameters for the recursive check_exec() call */ 195 epp->ep_ndp->ni_dirp = shellname; 196 epp->ep_ndp->ni_segflg = UIO_SYSSPACE; 197 epp->ep_flags |= EXEC_INDIR; 198 199 /* and set up the fake args list, for later */ 200 MALLOC(shellargp, char **, 4 * sizeof(char *), M_EXEC, M_WAITOK); 201 tmpsap = shellargp; 202 MALLOC(*tmpsap, char *, shellnamelen + 1, M_EXEC, M_WAITOK); 203 strcpy(*tmpsap++, shellname); 204 if (shellarg != NULL) { 205 MALLOC(*tmpsap, char *, shellarglen + 1, M_EXEC, M_WAITOK); 206 strcpy(*tmpsap++, shellarg); 207 } 208 MALLOC(*tmpsap, char *, MAXPATHLEN, M_EXEC, M_WAITOK); 209 #ifdef FDSCRIPTS 210 if ((epp->ep_flags & EXEC_HASFD) == 0) { 211 #endif 212 /* normally can't fail, but check for it if diagnostic */ 213 error = copyinstr(epp->ep_name, *tmpsap++, MAXPATHLEN, 214 (size_t *)0); 215 #ifdef DIAGNOSTIC 216 if (error != 0) 217 panic("exec_script: copyinstr couldn't fail\n"); 218 #endif 219 #ifdef FDSCRIPTS 220 } else 221 sprintf(*tmpsap++, "/dev/fd/%d", epp->ep_fd); 222 #endif 223 *tmpsap = NULL; 224 225 /* 226 * mark the header we have as invalid; check_exec will read 227 * the header from the new executable 228 */ 229 epp->ep_hdrvalid = 0; 230 231 /* 232 * remember the old vp and pnbuf for later, so we can restore 233 * them if check_exec() fails. 234 */ 235 scriptvp = epp->ep_vp; 236 oldpnbuf = epp->ep_ndp->ni_cnd.cn_pnbuf; 237 238 if ((error = check_exec(p, epp)) == 0) { 239 /* note that we've clobbered the header */ 240 epp->ep_flags |= EXEC_DESTR; 241 242 /* 243 * It succeeded. Unlock the script and 244 * close it if we aren't using it any more. 245 * Also, set things up so that the fake args 246 * list will be used. 247 */ 248 if ((epp->ep_flags & EXEC_HASFD) == 0) { 249 vn_lock(scriptvp, LK_EXCLUSIVE | LK_RETRY); 250 VOP_CLOSE(scriptvp, FREAD, p->p_ucred, p); 251 vput(scriptvp); 252 } 253 254 /* free the old pathname buffer */ 255 PNBUF_PUT(oldpnbuf); 256 257 epp->ep_flags |= (EXEC_HASARGL | EXEC_SKIPARG); 258 epp->ep_fa = shellargp; 259 #ifdef SETUIDSCRIPTS 260 /* 261 * set thing up so that set-id scripts will be 262 * handled appropriately 263 */ 264 epp->ep_vap->va_mode |= script_sbits; 265 if (script_sbits & S_ISUID) 266 epp->ep_vap->va_uid = script_uid; 267 if (script_sbits & S_ISGID) 268 epp->ep_vap->va_gid = script_gid; 269 #endif 270 return (0); 271 } 272 273 /* XXX oldpnbuf not set for "goto fail" path */ 274 epp->ep_ndp->ni_cnd.cn_pnbuf = oldpnbuf; 275 #ifdef FDSCRIPTS 276 fail: 277 #endif 278 /* note that we've clobbered the header */ 279 epp->ep_flags |= EXEC_DESTR; 280 281 /* kill the opened file descriptor, else close the file */ 282 if (epp->ep_flags & EXEC_HASFD) { 283 epp->ep_flags &= ~EXEC_HASFD; 284 (void) fdrelease(p, epp->ep_fd); 285 } else if (scriptvp) { 286 vn_lock(scriptvp, LK_EXCLUSIVE | LK_RETRY); 287 VOP_CLOSE(scriptvp, FREAD, p->p_ucred, p); 288 vput(scriptvp); 289 } 290 291 PNBUF_PUT(epp->ep_ndp->ni_cnd.cn_pnbuf); 292 293 /* free the fake arg list, because we're not returning it */ 294 if ((tmpsap = shellargp) != NULL) { 295 while (*tmpsap != NULL) { 296 FREE(*tmpsap, M_EXEC); 297 tmpsap++; 298 } 299 FREE(shellargp, M_EXEC); 300 } 301 302 /* 303 * free any vmspace-creation commands, 304 * and release their references 305 */ 306 kill_vmcmds(&epp->ep_vmcmds); 307 308 return error; 309 } 310
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