Annotation of src/sys/kern/exec_script.c, Revision 1.26
1.26 ! thorpej 1: /* $NetBSD: exec_script.c,v 1.25 2000/08/01 04:57:29 thorpej 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: */
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>
1.18 christos 44: #ifdef SETUIDSCRIPTS
45: #include <sys/stat.h>
46: #endif
1.1 cgd 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
1.25 thorpej 66: exec_script_makecmds(struct proc *p, struct exec_package *epp)
1.1 cgd 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
1.18 christos 74: /* Gcc needs those initialized for spurious uninitialized warning */
75: uid_t script_uid = (uid_t) -1;
76: gid_t script_gid = NOGROUP;
1.1 cgd 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: */
1.6 cgd 96: hdrlinelen = min(epp->ep_hdrvalid, MAXINTERP);
1.1 cgd 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;
1.13 christos 109: shellarglen = 0;
1.1 cgd 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: */
1.17 mycroft 149: script_sbits = epp->ep_vap->va_mode & (S_ISUID | S_ISGID);
1.1 cgd 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: */
1.19 fvdl 163: vn_lock(epp->ep_vp, LK_EXCLUSIVE | LK_RETRY);
1.14 cgd 164: error = VOP_ACCESS(epp->ep_vp, VREAD, p->p_ucred, p);
1.19 fvdl 165: VOP_UNLOCK(epp->ep_vp, 0);
1.14 cgd 166: if (error == EACCES
1.9 cgd 167: #ifdef SETUIDSCRIPTS
168: || script_sbits
169: #endif
170: ) {
1.1 cgd 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:
1.21 thorpej 178: /* falloc() will use the descriptor for us */
1.18 christos 179: if ((error = falloc(p, &fp, &epp->ep_fd)) != 0) {
180: scriptvp = NULL;
181: shellargp = NULL;
1.4 cgd 182: goto fail;
1.18 christos 183: }
1.1 cgd 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;
1.22 tv 190: FILE_UNUSE(fp, p);
1.1 cgd 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 */
1.11 mycroft 213: error = copyinstr(epp->ep_name, *tmpsap++, MAXPATHLEN,
214: (size_t *)0);
1.1 cgd 215: #ifdef DIAGNOSTIC
216: if (error != 0)
217: panic("exec_script: copyinstr couldn't fail\n");
218: #endif
219: #ifdef FDSCRIPTS
220: } else
1.16 christos 221: sprintf(*tmpsap++, "/dev/fd/%d", epp->ep_fd);
1.1 cgd 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;
1.7 mycroft 236: oldpnbuf = epp->ep_ndp->ni_cnd.cn_pnbuf;
1.1 cgd 237:
238: if ((error = check_exec(p, epp)) == 0) {
1.4 cgd 239: /* note that we've clobbered the header */
240: epp->ep_flags |= EXEC_DESTR;
241:
1.1 cgd 242: /*
243: * It succeeded. Unlock the script and
244: * close it if we aren't using it any more.
1.4 cgd 245: * Also, set things up so that the fake args
1.1 cgd 246: * list will be used.
247: */
1.14 cgd 248: if ((epp->ep_flags & EXEC_HASFD) == 0) {
1.20 wrstuden 249: vn_lock(scriptvp, LK_EXCLUSIVE | LK_RETRY);
1.14 cgd 250: VOP_CLOSE(scriptvp, FREAD, p->p_ucred, p);
1.20 wrstuden 251: vput(scriptvp);
1.14 cgd 252: }
1.2 cgd 253:
254: /* free the old pathname buffer */
1.26 ! thorpej 255: PNBUF_PUT(oldpnbuf);
1.1 cgd 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;
1.17 mycroft 265: if (script_sbits & S_ISUID)
1.1 cgd 266: epp->ep_vap->va_uid = script_uid;
1.17 mycroft 267: if (script_sbits & S_ISGID)
1.1 cgd 268: epp->ep_vap->va_gid = script_gid;
269: #endif
1.4 cgd 270: return (0);
271: }
272:
1.5 cgd 273: /* XXX oldpnbuf not set for "goto fail" path */
1.7 mycroft 274: epp->ep_ndp->ni_cnd.cn_pnbuf = oldpnbuf;
1.13 christos 275: #ifdef FDSCRIPTS
1.4 cgd 276: fail:
1.13 christos 277: #endif
1.4 cgd 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;
1.12 mycroft 284: (void) fdrelease(p, epp->ep_fd);
1.18 christos 285: } else if (scriptvp) {
1.20 wrstuden 286: vn_lock(scriptvp, LK_EXCLUSIVE | LK_RETRY);
1.14 cgd 287: VOP_CLOSE(scriptvp, FREAD, p->p_ucred, p);
1.20 wrstuden 288: vput(scriptvp);
1.14 cgd 289: }
1.4 cgd 290:
1.26 ! thorpej 291: PNBUF_PUT(epp->ep_ndp->ni_cnd.cn_pnbuf);
1.1 cgd 292:
1.4 cgd 293: /* free the fake arg list, because we're not returning it */
1.18 christos 294: if ((tmpsap = shellargp) != NULL) {
295: while (*tmpsap != NULL) {
296: FREE(*tmpsap, M_EXEC);
297: tmpsap++;
298: }
299: FREE(shellargp, M_EXEC);
1.1 cgd 300: }
1.4 cgd 301:
302: /*
303: * free any vmspace-creation commands,
304: * and release their references
305: */
306: kill_vmcmds(&epp->ep_vmcmds);
1.1 cgd 307:
1.4 cgd 308: return error;
1.1 cgd 309: }
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