pciconf -lv - /dev/pci error

[Robert Watson]

On Wed, 31 Dec 2003, William Michael Grim wrote:

> I have 5.1-RELEASE installed on my system, and I've never needed to do a
> "pciconf -lv" to probe the system before.  However, I tried doing it
> earlier today after logging in through SSH and doing "su -" to become
> superuser.  I received this error: 
> 
> [root at snow 09:12:42 root]# pciconf -lv
> pciconf: /dev/pci: Operation not permitted
> 
> [root at snow 09:15:41 root]# ls -l /dev/pci
> crw-r--r--  1 root  wheel  251,   0 Nov  2 05:09 /dev/pci
> 
> So, as you can see, the permissions are correct.  Perhaps I don't have
> something compiled into my kernel?  I can attach a dmesg and kernel
> config if it's necessary. 

pciconf -lv appears to cause pciconf to open /dev/pci writable:

   731 pciconf  CALL  open(0x8049a55,0x2,0)
   731 pciconf  NAMI  "/dev/pci"
   731 pciconf  RET   open -1 errno 13 Permission denied

And, of course, it's not writable by non-root.  The attached patch causes
pciconf to open /dev/pci read-only when listing devices (apply to
usr.sbin/pciconf/pciconf.c): 

Index: pciconf.c
===================================================================
RCS file: /home/ncvs/src/usr.sbin/pciconf/pciconf.c,v
retrieving revision 1.19
diff -u -r1.19 pciconf.c
--- pciconf.c	20 Jun 2003 23:59:25 -0000	1.19
+++ pciconf.c	31 Dec 2003 17:58:45 -0000
@@ -165,7 +165,7 @@
 	if (verbose)
 		load_vendors();
 
-	fd = open(_PATH_DEVPCI, O_RDWR, 0);
+	fd = open(_PATH_DEVPCI, O_RDONLY, 0);
 	if (fd < 0)
 		err(1, "%s", _PATH_DEVPCI);
 


The pci_user.c code in the kernel requires that the caller hold a writable
file descriptor for most of the ioctls; the exception is PCIOCGETCONF,
which is the only ioctl pciconf's list_devs() uses.  We can probably just
go ahead and commit this patch, I think.  The reason a check was added to
the kernel pci ioctl code is that unaligned writes to /dev/pci can cause
faults, I believe... 

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert at fledge.watson.org      Senior Research Scientist, McAfee Research