Date: Wed, 31 Dec 2003 13:01:06 -0500 (EST) From: Robert Watson <rwatson@freebsd.org> To: William Michael Grim <wgrim@siue.edu> Cc: hackers@freebsd.org Subject: Re: pciconf -lv - /dev/pci error Message-ID: <Pine.NEB.3.96L.1031231125153.54208A-100000@fledge.watson.org> In-Reply-To: <Pine.SO4.4.05.10312310916470.24534-100000@cougar.isg.siue.edu>
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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@snow 09:12:42 root]# pciconf -lv > pciconf: /dev/pci: Operation not permitted > > [root@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@fledge.watson.org Senior Research Scientist, McAfee Research
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