/*
* Copyright (c) 1993, 1994, 1996 Christopher G. Demetriou
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Christopher G. Demetriou.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
static int
exec_script_modcmd(modcmd_t cmd, void *arg)
{
switch (cmd) {
case MODULE_CMD_INIT:
return exec_add(&exec_script_execsw, 1);
case MODULE_CMD_FINI:
return exec_remove(&exec_script_execsw, 1);
case MODULE_CMD_AUTOUNLOAD:
/*
* We don't want to be autounloaded because our use is
* transient: no executables with p_execsw equal to
* exec_script_execsw will exist, so FINI will never
* return EBUSY. However, the system will run scripts
* often. Return EBUSY here to prevent this module from
* ping-ponging in and out of the kernel.
*/
return SET_ERROR(EBUSY);
default:
return SET_ERROR(ENOTTY);
}
}
/*
* exec_script_makecmds(): Check if it's an executable shell script.
*
* Given a proc pointer and an exec package pointer, see if the referent
* of the epp is in shell script. If it is, then set thing up so that
* the script can be run. This involves preparing the address space
* and arguments for the shell which will run the script.
*
* This function is ultimately responsible for creating a set of vmcmds
* which can be used to build the process's vm space and inserting them
* into the exec package.
*/
int
exec_script_makecmds(struct lwp *l, struct exec_package *epp)
{
int error, hdrlinelen, shellnamelen, shellarglen;
char *hdrstr = epp->ep_hdr;
char *cp, *shellname, *shellarg;
size_t shellargp_len;
struct exec_fakearg *shellargp;
struct exec_fakearg *tmpsap;
struct pathbuf *shell_pathbuf;
struct vnode *scriptvp;
#ifdef SETUIDSCRIPTS
/* Gcc needs those initialized for spurious uninitialized warning */
uid_t script_uid = (uid_t) -1;
gid_t script_gid = NOGROUP;
u_short script_sbits;
#endif
/*
* if the magic isn't that of a shell script, or we've already
* done shell script processing for this exec, punt on it.
*/
if ((epp->ep_flags & EXEC_INDIR) != 0 ||
epp->ep_hdrvalid < EXEC_SCRIPT_MAGICLEN ||
strncmp(hdrstr, EXEC_SCRIPT_MAGIC, EXEC_SCRIPT_MAGICLEN))
return SET_ERROR(ENOEXEC);
/*
* Check that the shell spec is terminated by a newline, and that
* it isn't too large.
*/
hdrlinelen = uimin(epp->ep_hdrvalid, SCRIPT_HDR_SIZE);
for (cp = hdrstr + EXEC_SCRIPT_MAGICLEN; cp < hdrstr + hdrlinelen;
cp++) {
if (*cp == '\n') {
*cp = '\0';
break;
}
}
if (cp >= hdrstr + hdrlinelen)
return SET_ERROR(ENOEXEC);
/* strip spaces before the shell name */
for (cp = hdrstr + EXEC_SCRIPT_MAGICLEN; *cp == ' ' || *cp == '\t';
cp++)
;
if (*cp == '\0')
return SET_ERROR(ENOEXEC);
shellarg = NULL;
shellarglen = 0;
/* collect the shell name; remember its length for later */
shellname = cp;
shellnamelen = 0;
for ( /* cp = cp */ ; *cp != '\0' && *cp != ' ' && *cp != '\t'; cp++)
shellnamelen++;
if (*cp == '\0')
goto check_shell;
*cp++ = '\0';
/* skip spaces before any argument */
for ( /* cp = cp */ ; *cp == ' ' || *cp == '\t'; cp++)
;
if (*cp == '\0')
goto check_shell;
/*
* collect the shell argument. everything after the shell name
* is passed as ONE argument; that's the correct (historical)
* behaviour.
*/
shellarg = cp;
for ( /* cp = cp */ ; *cp != '\0'; cp++)
shellarglen++;
*cp++ = '\0';
check_shell:
#ifdef SETUIDSCRIPTS
/*
* MNT_NOSUID has already taken care of by check_exec,
* so we don't need to worry about it now or later. We
* will need to check PSL_TRACED later, however.
*/
script_sbits = epp->ep_vap->va_mode & (S_ISUID | S_ISGID);
if (script_sbits != 0) {
script_uid = epp->ep_vap->va_uid;
script_gid = epp->ep_vap->va_gid;
}
#endif
#ifdef FDSCRIPTS
/*
* if the script isn't readable, or it's set-id, then we've
* gotta supply a "/dev/fd/..." for the shell to read.
* Note that stupid shells (csh) do the wrong thing, and
* close all open fd's when they start. That kills this
* method of implementing "safe" set-id and x-only scripts.
*/
vn_lock(epp->ep_vp, LK_SHARED | LK_RETRY);
error = VOP_ACCESS(epp->ep_vp, VREAD, l->l_cred);
VOP_UNLOCK(epp->ep_vp);
if (error == EACCES
#ifdef SETUIDSCRIPTS
|| script_sbits
#endif
) {
struct file *fp;
/* note that we've clobbered the header */
epp->ep_flags |= EXEC_DESTR;
if (error == 0) {
/*
* It succeeded. Unlock the script and
* close it if we aren't using it any more.
* Also, set things up so that the fake args
* list will be used.
*/
if ((epp->ep_flags & EXEC_HASFD) == 0) {
vn_lock(scriptvp, LK_EXCLUSIVE | LK_RETRY);
VOP_CLOSE(scriptvp, FREAD, l->l_cred);
vput(scriptvp);
}
epp->ep_flags |= (EXEC_HASARGL | EXEC_SKIPARG);
epp->ep_fa = shellargp;
epp->ep_fa_len = shellargp_len;
#ifdef SETUIDSCRIPTS
/*
* set thing up so that set-id scripts will be
* handled appropriately. PSL_TRACED will be
* checked later when the shell is actually
* exec'd.
*/
epp->ep_vap->va_mode |= script_sbits;
if (script_sbits & S_ISUID)
epp->ep_vap->va_uid = script_uid;
if (script_sbits & S_ISGID)
epp->ep_vap->va_gid = script_gid;
#endif
return (0);
}
#ifdef FDSCRIPTS
fail:
#endif
/* kill the opened file descriptor, else close the file */
if (epp->ep_flags & EXEC_HASFD) {
epp->ep_flags &= ~EXEC_HASFD;
fd_close(epp->ep_fd);
} else if (scriptvp) {
vn_lock(scriptvp, LK_EXCLUSIVE | LK_RETRY);
VOP_CLOSE(scriptvp, FREAD, l->l_cred);
vput(scriptvp);
}
/* free the fake arg list, because we're not returning it */
if ((tmpsap = shellargp) != NULL) {
while (tmpsap->fa_arg != NULL) {
kmem_free(tmpsap->fa_arg, tmpsap->fa_len);
tmpsap++;
}
kmem_free(shellargp, shellargp_len);
}
/*
* free any vmspace-creation commands,
* and release their references
*/
kill_vmcmds(&epp->ep_vmcmds);
