shbin.c revision 93cf283ac1d0119d2ee3842f515f8d0e1bc7cbdb
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2010 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#include <sys/types.h>
#include <sys/param.h>
#include <sys/sysmacros.h>
#include <sys/signal.h>
#include <sys/cred.h>
#include <sys/user.h>
#include <sys/errno.h>
#include <sys/vnode.h>
#include <sys/proc.h>
#include <sys/cmn_err.h>
#include <sys/debug.h>
#include <sys/pathname.h>
#include <sys/disp.h>
#include <sys/exec.h>
#include <sys/kmem.h>
#include <sys/note.h>
/*
* This is the loadable module wrapper.
*/
#include <sys/modctl.h>
/* Local prototypes */
static int
shbinexec(
struct vnode *vp,
struct execa *uap,
struct uarg *args,
struct intpdata *idatap,
int level,
long *execsz,
int setid,
caddr_t exec_file,
struct cred *cred,
int brand_action);
#define SHBIN_CNTL(x) ((x)&037)
#define SHBINMAGIC_LEN 4
extern char shbinmagicstr[];
/*
* Our list where we may find a copy of ksh93. The ordering is:
* 1. 64bit (may not be installed or not supported in hardware)
* 2. 32bit
* 3. Use /sbin/ksh93 when /usr is not available
*
* ([1] and [2] explicitly bypass /usr/bin/ksh93 to avoid the
* isaexec overhead).
*/
static char *shell_list[] =
{
/* Bypass /usr/bin/ksh93 (which is "isaexec") for performance */
#if defined(__sparc)
"/usr/bin/sparcv9/ksh93",
"/usr/bin/sparcv7/ksh93",
#elif defined(__amd64)
"/usr/bin/amd64/ksh93",
"/usr/bin/i86/ksh93",
#elif defined(__i386)
"/usr/bin/i86/ksh93",
#else
#error "Unrecognized platform/CPU (use /usr/bin/ksh93 when in doubt)."
#endif
"/sbin/ksh93",
NULL
};
static struct execsw esw = {
shbinmagicstr,
0,
SHBINMAGIC_LEN,
shbinexec,
NULL
};
/*
* Module linkage information for the kernel.
*/
extern struct mod_ops mod_execops;
static struct modlexec modlexec = {
&mod_execops, "exec mod for shell binaries (ksh93)", &esw
};
static struct modlinkage modlinkage = {
MODREV_1, (void *)&modlexec, NULL
};
int
_init(void)
{
return (mod_install(&modlinkage));
}
int
_fini(void)
{
return (mod_remove(&modlinkage));
}
int
_info(struct modinfo *modinfop)
{
return (mod_info(&modlinkage, modinfop));
}
static int
checkshbinmagic(struct vnode *vp)
{
int error;
char linep[SHBINMAGIC_LEN];
ssize_t resid;
/*
* Read the entire line and confirm that it starts with the magic
* sequence for compiled ksh93 shell scripts.
*/
if (error = vn_rdwr(UIO_READ, vp, linep, sizeof (linep), (offset_t)0,
UIO_SYSSPACE, 0, (rlim64_t)0, CRED(), &resid))
return (error);
if (memcmp(linep, shbinmagicstr, SHBINMAGIC_LEN) != 0)
return (ENOEXEC);
return (0);
}
static int
shbinexec(
struct vnode *vp,
struct execa *uap,
struct uarg *args,
struct intpdata *idatap,
int level,
long *execsz,
int setid,
caddr_t exec_file,
struct cred *cred,
int brand_action)
{
_NOTE(ARGUNUSED(brand_action))
vnode_t *nvp;
int error = 0;
struct intpdata idata;
struct pathname intppn;
struct pathname resolvepn;
char *opath;
char devfd[19]; /* 32-bit int fits in 10 digits + 8 for "/dev/fd/" */
int fd = -1;
int i;
if (level) { /* Can't recurse */
error = ENOEXEC;
goto bad;
}
ASSERT(idatap == (struct intpdata *)NULL);
/*
* Check whether the executable has the correct magic value.
*/
if (error = checkshbinmagic(vp))
goto fail;
pn_alloc(&resolvepn);
/*
* Travel the list of shells and look for one which is available...
*/
for (i = 0; shell_list[i] != NULL; i++) {
error = pn_get(shell_list[i], UIO_SYSSPACE, &intppn);
if (error != 0) {
break;
}
error = lookuppn(&intppn, &resolvepn, FOLLOW, NULLVPP, &nvp);
if (!error) {
/* Found match */
break;
}
/* No match found ? Then continue with the next item... */
pn_free(&intppn);
}
if (error) {
pn_free(&resolvepn);
goto fail;
}
/*
* Setup interpreter data
* "--" is passed to mark the end-of-arguments before adding
* the scripts file name, preventing problems when a
* a script's name starts with a '-' character.
*/
idata.intp = NULL;
idata.intp_name[0] = shell_list[i];
idata.intp_arg[0] = "--";
opath = args->pathname;
args->pathname = resolvepn.pn_path;
/* don't free resolvepn until we are done with args */
pn_free(&intppn);
/*
* When we're executing a set-uid script resulting in uids
* mismatching or when we execute with additional privileges,
* we close the "replace script between exec and open by shell"
* hole by passing the script as /dev/fd parameter.
*/
if ((setid & EXECSETID_PRIVS) != 0 ||
(setid & (EXECSETID_UGIDS|EXECSETID_SETID)) ==
(EXECSETID_UGIDS|EXECSETID_SETID)) {
(void) strcpy(devfd, "/dev/fd/");
if (error = execopen(&vp, &fd))
goto done;
numtos(fd, &devfd[8]);
args->fname = devfd;
}
error = gexec(&nvp, uap, args, &idata, ++level, execsz, exec_file, cred,
EBA_NONE);
if (!error) {
/*
* Close this script as the sh interpreter
* will open and close it later on.
*/
(void) VOP_CLOSE(vp, FREAD, 1, (offset_t)0, cred, NULL);
}
done:
VN_RELE(nvp);
args->pathname = opath;
pn_free(&resolvepn);
fail:
if (error && fd != -1)
(void) execclose(fd);
bad:
return (error);
}