Solaris 9: USCSICMD ioctl on volume management devices fails

Question

Upto and including Solaris 8, it was possible to use the USCSICMD
ioctl on devices managed by the vold daemon (e.g. the CDROM device,
/vol/dev/aliases/cdrom0) without the need for root permission.
It seems this does not work any more with Solaris 9, it requires
root permission now.
An example program is appended below. On Solaris 8 with a uid != 0
it prints the CDROM drive's manufacturer and product id:
% uname -r
5.8
% id
uid=109(jk) gid=20(usr)
% vol
TOSHIBA DVD-ROM SD-M1612
It seems that on Solaris 9, the USCSICMD ioctl fails with an EPERM
error. Can anyone reproduce this on Solaris 9?
Is this a Solaris 9 bug, or a Solaris 9 feature?
/* compile with: cc -o vol vol.c */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/scsi/generic/commands.h>
#include <sys/scsi/impl/uscsi.h>
#define     CD_DEVICE     "/vol/dev/aliases/cdrom0"
/* execute a SCSI INQUIRY command on device |fd| */
int inquiry(int fd, void *inq_data, int inq_len)
struct uscsi_cmd sc;
union scsi_cdb inq_cdb;
memset(&inq_cdb, 0, sizeof(inq_cdb));
inq_cdb.scc_cmd = SCMD_INQUIRY;
inq_cdb.g0_count0 = inq_len;
memset(&sc, 0, sizeof(sc));
sc.uscsi_cdb = (caddr_t)&inq_cdb;
sc.uscsi_cdblen = 6;
sc.uscsi_bufaddr = inq_data;
sc.uscsi_buflen = inq_len;
sc.uscsi_flags = USCSI_ISOLATE|USCSI_READ;
if (ioctl(fd, USCSICMD, &sc)) {
     perror("USCSICMD ioctl, inquiry");
     exit(1);
if (sc.uscsi_status) {
     fprintf(stderr, "bad status for INQUIRY command (%d)\n",
          sc.uscsi_status);
     return -1;
return 0;
int main(int argc, char **argv)
struct scsi_inquiry inq_data;
int fd;
char *cd_device = CD_DEVICE;
if ((fd = open(cd_device, O_RDONLY)) < 0) {
     perror(cd_device);
     exit(1);
if (inquiry(fd, &inq_data, sizeof(inq_data))) {
     fprintf(stderr, "scsi inquiry command failed\n");
     exit(1);
/* print vendor/product from scsi inquiry data */
printf("%.*s %.*s\n",
     sizeof(inq_data.inq_vid), inq_data.inq_vid,
     sizeof(inq_data.inq_pid), inq_data.inq_pid);
exit(0);

Answer 1

According to a usenet thread (where I posted the same question)...
http://groups.google.de/groups?hl=de&lr=&ie=UTF-8&oe=UTF-8&selm=wyvg45125q.fsf%40tools.de
... it's a security enhancement. Or in other words: It's a feature, not a bug.
It's possible to work around the problem in your own programs using
the "-lsmedia" library, but this is not (yet?) a supported interface, it seems:
#include <sys/smedia.h>
int fd = open("/vol/dev/...", ...);
struct uscsi_cmd scsi_cmd;
smedia_handle_t handle = smedia_get_handle(fd);
/* fill in scsi_cmd structure ... */
smedia_uscsi_cmd(handle, &scsi_cmd);
smedia_release_handle(handle);