lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Tue, 6 Oct 2015 17:40:23 +0300 From: Vlad Zolotarov <vladz@...udius-systems.com> To: "Michael S. Tsirkin" <mst@...hat.com> Cc: linux-kernel@...r.kernel.org, hjk@...sjkoch.de, corbet@....net, gregkh@...uxfoundation.org, bruce.richardson@...el.com, avi@...udius-systems.com, gleb@...udius-systems.com, stephen@...workplumber.org, alexander.duyck@...il.com Subject: Re: [PATCH v3 0/3] uio: add MSI/MSI-X support to uio_pci_generic driver On 10/06/15 17:30, Michael S. Tsirkin wrote: > On Tue, Oct 06, 2015 at 11:37:59AM +0300, Vlad Zolotarov wrote: >> Bus mastering is easily enabled from the user space (taken from DPDK code): >> >> static int >> pci_uio_set_bus_master(int dev_fd) >> { >> uint16_t reg; >> int ret; >> >> ret = pread(dev_fd, ®, sizeof(reg), PCI_COMMAND); >> if (ret != sizeof(reg)) { >> RTE_LOG(ERR, EAL, >> "Cannot read command from PCI config space!\n"); >> return -1; >> } >> >> /* return if bus mastering is already on */ >> if (reg & PCI_COMMAND_MASTER) >> return 0; >> >> reg |= PCI_COMMAND_MASTER; >> >> ret = pwrite(dev_fd, ®, sizeof(reg), PCI_COMMAND); >> if (ret != sizeof(reg)) { >> RTE_LOG(ERR, EAL, >> "Cannot write command to PCI config space!\n"); >> return -1; >> } >> >> return 0; >> } >> >> So, this is a non-issue. ;) > There might be valid reasons for DPDK to do this, e.g. if using VFIO. Michael, I'm afraid u are missing the main point here - the code above destroys all your long arguments. U can't possibly prevent the root-user from enabling the device bus mastering. And as me and other people on this thread have already mentioned MSI and MSI-X device configuration is controlled from the device BAR, thus may not be prevented too. > > I'm guessing it doesn't enable MSI though, does it? Again, enabling MSI is a matter of a trivial patch configuring device registers on the device BAR. > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists