Annotation of src/sys/kern/exec_script.c, Revision 1.36
1.35 darrenr 1: /* $NetBSD: exec_script.c,v 1.34 2003/05/16 14:25:03 itojun Exp $ */
1.8 cgd 2:
1.1 cgd 3: /*
1.14 cgd 4: * Copyright (c) 1993, 1994, 1996 Christopher G. Demetriou
1.1 cgd 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
1.3 jtc 19: * derived from this software without specific prior written permission
1.1 cgd 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: */
1.30 lukem 32:
33: #include <sys/cdefs.h>
1.35 darrenr 34: __KERNEL_RCSID(0, "$NetBSD: exec_script.c,v 1.34 2003/05/16 14:25:03 itojun Exp $");
1.1 cgd 35:
36: #if defined(SETUIDSCRIPTS) && !defined(FDSCRIPTS)
37: #define FDSCRIPTS /* Need this for safe set-id scripts. */
38: #endif
39:
40: #include <sys/param.h>
41: #include <sys/systm.h>
42: #include <sys/proc.h>
43: #include <sys/malloc.h>
44: #include <sys/vnode.h>
45: #include <sys/namei.h>
46: #include <sys/file.h>
1.18 christos 47: #ifdef SETUIDSCRIPTS
48: #include <sys/stat.h>
49: #endif
1.1 cgd 50: #include <sys/filedesc.h>
51: #include <sys/exec.h>
52: #include <sys/resourcevar.h>
53:
54: #include <sys/exec_script.h>
55:
56: /*
57: * exec_script_makecmds(): Check if it's an executable shell script.
58: *
59: * Given a proc pointer and an exec package pointer, see if the referent
60: * of the epp is in shell script. If it is, then set thing up so that
61: * the script can be run. This involves preparing the address space
62: * and arguments for the shell which will run the script.
63: *
64: * This function is ultimately responsible for creating a set of vmcmds
65: * which can be used to build the process's vm space and inserting them
66: * into the exec package.
67: */
68: int
1.36 ! fvdl 69: exec_script_makecmds(struct proc *p, struct exec_package *epp)
1.1 cgd 70: {
71: int error, hdrlinelen, shellnamelen, shellarglen;
72: char *hdrstr = epp->ep_hdr;
73: char *cp, *shellname, *shellarg, *oldpnbuf;
74: char **shellargp, **tmpsap;
75: struct vnode *scriptvp;
76: #ifdef SETUIDSCRIPTS
1.18 christos 77: /* Gcc needs those initialized for spurious uninitialized warning */
78: uid_t script_uid = (uid_t) -1;
79: gid_t script_gid = NOGROUP;
1.1 cgd 80: u_short script_sbits;
81: #endif
82:
83: /*
84: * if the magic isn't that of a shell script, or we've already
85: * done shell script processing for this exec, punt on it.
86: */
87: if ((epp->ep_flags & EXEC_INDIR) != 0 ||
88: epp->ep_hdrvalid < EXEC_SCRIPT_MAGICLEN ||
89: strncmp(hdrstr, EXEC_SCRIPT_MAGIC, EXEC_SCRIPT_MAGICLEN))
90: return ENOEXEC;
91:
92: /*
93: * check that the shell spec is terminated by a newline,
94: * and that it isn't too large. Don't modify the
95: * buffer unless we're ready to commit to handling it.
96: * (The latter requirement means that we have to check
97: * for both spaces and tabs later on.)
98: */
1.33 perry 99: hdrlinelen = min(epp->ep_hdrvalid, SCRIPT_HDR_SIZE);
1.1 cgd 100: for (cp = hdrstr + EXEC_SCRIPT_MAGICLEN; cp < hdrstr + hdrlinelen;
101: cp++) {
102: if (*cp == '\n') {
103: *cp = '\0';
104: break;
105: }
106: }
107: if (cp >= hdrstr + hdrlinelen)
108: return ENOEXEC;
109:
110: shellname = NULL;
111: shellarg = NULL;
1.13 christos 112: shellarglen = 0;
1.1 cgd 113:
114: /* strip spaces before the shell name */
115: for (cp = hdrstr + EXEC_SCRIPT_MAGICLEN; *cp == ' ' || *cp == '\t';
116: cp++)
117: ;
118:
119: /* collect the shell name; remember it's length for later */
120: shellname = cp;
121: shellnamelen = 0;
122: if (*cp == '\0')
123: goto check_shell;
124: for ( /* cp = cp */ ; *cp != '\0' && *cp != ' ' && *cp != '\t'; cp++)
125: shellnamelen++;
126: if (*cp == '\0')
127: goto check_shell;
128: *cp++ = '\0';
129:
130: /* skip spaces before any argument */
131: for ( /* cp = cp */ ; *cp == ' ' || *cp == '\t'; cp++)
132: ;
133: if (*cp == '\0')
134: goto check_shell;
135:
136: /*
137: * collect the shell argument. everything after the shell name
138: * is passed as ONE argument; that's the correct (historical)
139: * behaviour.
140: */
141: shellarg = cp;
142: for ( /* cp = cp */ ; *cp != '\0'; cp++)
143: shellarglen++;
144: *cp++ = '\0';
145:
146: check_shell:
147: #ifdef SETUIDSCRIPTS
148: /*
1.29 thorpej 149: * MNT_NOSUID has already taken care of by check_exec,
150: * so we don't need to worry about it now or later. We
151: * will need to check P_TRACED later, however.
1.1 cgd 152: */
1.17 mycroft 153: script_sbits = epp->ep_vap->va_mode & (S_ISUID | S_ISGID);
1.1 cgd 154: if (script_sbits != 0) {
155: script_uid = epp->ep_vap->va_uid;
156: script_gid = epp->ep_vap->va_gid;
157: }
158: #endif
159: #ifdef FDSCRIPTS
160: /*
161: * if the script isn't readable, or it's set-id, then we've
162: * gotta supply a "/dev/fd/..." for the shell to read.
163: * Note that stupid shells (csh) do the wrong thing, and
164: * close all open fd's when the start. That kills this
165: * method of implementing "safe" set-id and x-only scripts.
166: */
1.19 fvdl 167: vn_lock(epp->ep_vp, LK_EXCLUSIVE | LK_RETRY);
1.14 cgd 168: error = VOP_ACCESS(epp->ep_vp, VREAD, p->p_ucred, p);
1.19 fvdl 169: VOP_UNLOCK(epp->ep_vp, 0);
1.14 cgd 170: if (error == EACCES
1.9 cgd 171: #ifdef SETUIDSCRIPTS
172: || script_sbits
173: #endif
174: ) {
1.1 cgd 175: struct file *fp;
176:
177: #if defined(DIAGNOSTIC) && defined(FDSCRIPTS)
178: if (epp->ep_flags & EXEC_HASFD)
179: panic("exec_script_makecmds: epp already has a fd");
180: #endif
181:
1.21 thorpej 182: /* falloc() will use the descriptor for us */
1.18 christos 183: if ((error = falloc(p, &fp, &epp->ep_fd)) != 0) {
184: scriptvp = NULL;
185: shellargp = NULL;
1.4 cgd 186: goto fail;
1.18 christos 187: }
1.1 cgd 188:
189: epp->ep_flags |= EXEC_HASFD;
190: fp->f_type = DTYPE_VNODE;
191: fp->f_ops = &vnops;
192: fp->f_data = (caddr_t) epp->ep_vp;
193: fp->f_flag = FREAD;
1.28 thorpej 194: FILE_SET_MATURE(fp);
1.22 tv 195: FILE_UNUSE(fp, p);
1.1 cgd 196: }
197: #endif
198:
199: /* set up the parameters for the recursive check_exec() call */
200: epp->ep_ndp->ni_dirp = shellname;
201: epp->ep_ndp->ni_segflg = UIO_SYSSPACE;
202: epp->ep_flags |= EXEC_INDIR;
203:
204: /* and set up the fake args list, for later */
205: MALLOC(shellargp, char **, 4 * sizeof(char *), M_EXEC, M_WAITOK);
206: tmpsap = shellargp;
207: MALLOC(*tmpsap, char *, shellnamelen + 1, M_EXEC, M_WAITOK);
1.34 itojun 208: strlcpy(*tmpsap++, shellname, shellnamelen + 1);
1.1 cgd 209: if (shellarg != NULL) {
210: MALLOC(*tmpsap, char *, shellarglen + 1, M_EXEC, M_WAITOK);
1.34 itojun 211: strlcpy(*tmpsap++, shellarg, shellarglen + 1);
1.1 cgd 212: }
213: MALLOC(*tmpsap, char *, MAXPATHLEN, M_EXEC, M_WAITOK);
214: #ifdef FDSCRIPTS
215: if ((epp->ep_flags & EXEC_HASFD) == 0) {
216: #endif
217: /* normally can't fail, but check for it if diagnostic */
1.11 mycroft 218: error = copyinstr(epp->ep_name, *tmpsap++, MAXPATHLEN,
219: (size_t *)0);
1.1 cgd 220: #ifdef DIAGNOSTIC
221: if (error != 0)
1.31 provos 222: panic("exec_script: copyinstr couldn't fail");
1.1 cgd 223: #endif
224: #ifdef FDSCRIPTS
225: } else
1.16 christos 226: sprintf(*tmpsap++, "/dev/fd/%d", epp->ep_fd);
1.1 cgd 227: #endif
228: *tmpsap = NULL;
229:
230: /*
231: * mark the header we have as invalid; check_exec will read
232: * the header from the new executable
233: */
234: epp->ep_hdrvalid = 0;
235:
236: /*
237: * remember the old vp and pnbuf for later, so we can restore
238: * them if check_exec() fails.
239: */
240: scriptvp = epp->ep_vp;
1.7 mycroft 241: oldpnbuf = epp->ep_ndp->ni_cnd.cn_pnbuf;
1.1 cgd 242:
1.32 blymn 243: #ifdef VERIFIED_EXEC
1.36 ! fvdl 244: if ((error = check_exec(p, epp, 0)) == 0) {
1.32 blymn 245: #else
1.36 ! fvdl 246: if ((error = check_exec(p, epp)) == 0) {
1.32 blymn 247: #endif
1.4 cgd 248: /* note that we've clobbered the header */
1.27 jdolecek 249: epp->ep_flags |= EXEC_DESTR|EXEC_HASES;
1.4 cgd 250:
1.1 cgd 251: /*
252: * It succeeded. Unlock the script and
253: * close it if we aren't using it any more.
1.4 cgd 254: * Also, set things up so that the fake args
1.1 cgd 255: * list will be used.
256: */
1.14 cgd 257: if ((epp->ep_flags & EXEC_HASFD) == 0) {
1.20 wrstuden 258: vn_lock(scriptvp, LK_EXCLUSIVE | LK_RETRY);
1.36 ! fvdl 259: VOP_CLOSE(scriptvp, FREAD, p->p_ucred, p);
1.20 wrstuden 260: vput(scriptvp);
1.14 cgd 261: }
1.2 cgd 262:
263: /* free the old pathname buffer */
1.26 thorpej 264: PNBUF_PUT(oldpnbuf);
1.1 cgd 265:
266: epp->ep_flags |= (EXEC_HASARGL | EXEC_SKIPARG);
267: epp->ep_fa = shellargp;
268: #ifdef SETUIDSCRIPTS
269: /*
270: * set thing up so that set-id scripts will be
1.29 thorpej 271: * handled appropriately. P_TRACED will be
272: * checked later when the shell is actually
273: * exec'd.
1.1 cgd 274: */
275: epp->ep_vap->va_mode |= script_sbits;
1.17 mycroft 276: if (script_sbits & S_ISUID)
1.1 cgd 277: epp->ep_vap->va_uid = script_uid;
1.17 mycroft 278: if (script_sbits & S_ISGID)
1.1 cgd 279: epp->ep_vap->va_gid = script_gid;
280: #endif
1.4 cgd 281: return (0);
282: }
283:
1.5 cgd 284: /* XXX oldpnbuf not set for "goto fail" path */
1.7 mycroft 285: epp->ep_ndp->ni_cnd.cn_pnbuf = oldpnbuf;
1.13 christos 286: #ifdef FDSCRIPTS
1.4 cgd 287: fail:
1.13 christos 288: #endif
1.4 cgd 289: /* note that we've clobbered the header */
290: epp->ep_flags |= EXEC_DESTR;
291:
292: /* kill the opened file descriptor, else close the file */
293: if (epp->ep_flags & EXEC_HASFD) {
294: epp->ep_flags &= ~EXEC_HASFD;
1.36 ! fvdl 295: (void) fdrelease(p, epp->ep_fd);
1.18 christos 296: } else if (scriptvp) {
1.20 wrstuden 297: vn_lock(scriptvp, LK_EXCLUSIVE | LK_RETRY);
1.36 ! fvdl 298: VOP_CLOSE(scriptvp, FREAD, p->p_ucred, p);
1.20 wrstuden 299: vput(scriptvp);
1.14 cgd 300: }
1.4 cgd 301:
1.26 thorpej 302: PNBUF_PUT(epp->ep_ndp->ni_cnd.cn_pnbuf);
1.1 cgd 303:
1.4 cgd 304: /* free the fake arg list, because we're not returning it */
1.18 christos 305: if ((tmpsap = shellargp) != NULL) {
306: while (*tmpsap != NULL) {
307: FREE(*tmpsap, M_EXEC);
308: tmpsap++;
309: }
310: FREE(shellargp, M_EXEC);
1.1 cgd 311: }
1.4 cgd 312:
313: /*
314: * free any vmspace-creation commands,
315: * and release their references
316: */
317: kill_vmcmds(&epp->ep_vmcmds);
1.1 cgd 318:
1.4 cgd 319: return error;
1.1 cgd 320: }
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