PCI: Lock down BAR access when the kernel is locked down

Any hardware that can potentially generate DMA has to be locked down in
order to avoid it being possible for an attacker to modify kernel code,
allowing them to circumvent disabled module loading or module signing.
Default to paranoid - in future we can potentially relax this for
sufficiently IOMMU-isolated devices.

Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Gbp-Pq: Topic features/all/lockdown
Gbp-Pq: Name 0050-PCI-Lock-down-BAR-access-when-the-kernel-is-locked-d.patch

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 7ac258fd3c5ce0d4b87fb47241ccdbe9215a4107..7d29b03d9321933ae1352da59968167200330288 100644 (file)
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -727,6 +727,9 @@ static ssize_t pci_write_config(struct file *filp, struct kobject *kobj,
        loff_t init_off = off;
        u8 *data = (u8 *) buf;
 
+       if (kernel_is_locked_down())
+               return -EPERM;
+
        if (off > dev->cfg_size)
                return 0;
        if (off + count > dev->cfg_size) {
@@ -1022,6 +1025,9 @@ static int pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr,
        resource_size_t start, end;
        int i;
 
+       if (kernel_is_locked_down())
+               return -EPERM;
+
        for (i = 0; i < PCI_ROM_RESOURCE; i++)
                if (res == &pdev->resource[i])
                        break;
@@ -1121,6 +1127,9 @@ static ssize_t pci_write_resource_io(struct file *filp, struct kobject *kobj,
                                     struct bin_attribute *attr, char *buf,
                                     loff_t off, size_t count)
 {
+       if (kernel_is_locked_down())
+               return -EPERM;
+
        return pci_resource_io(filp, kobj, attr, buf, off, count, true);
 }
 

diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c
index dc8912e2d4a1c12a9cf336c2172ed6f48b8bca8d..e2c5eff543f197bc9f8eb7a7733c8fb445e91c51 100644 (file)
--- a/drivers/pci/proc.c
+++ b/drivers/pci/proc.c
@@ -116,6 +116,9 @@ static ssize_t proc_bus_pci_write(struct file *file, const char __user *buf,
        int size = dev->cfg_size;
        int cnt;
 
+       if (kernel_is_locked_down())
+               return -EPERM;
+
        if (pos >= size)
                return 0;
        if (nbytes >= size)
@@ -195,6 +198,9 @@ static long proc_bus_pci_ioctl(struct file *file, unsigned int cmd,
 #endif /* HAVE_PCI_MMAP */
        int ret = 0;
 
+       if (kernel_is_locked_down())
+               return -EPERM;
+
        switch (cmd) {
        case PCIIOC_CONTROLLER:
                ret = pci_domain_nr(dev->bus);
@@ -233,7 +239,7 @@ static int proc_bus_pci_mmap(struct file *file, struct vm_area_struct *vma)
        struct pci_filp_private *fpriv = file->private_data;
        int i, ret, write_combine = 0, res_bit;
 
-       if (!capable(CAP_SYS_RAWIO))
+       if (!capable(CAP_SYS_RAWIO) || kernel_is_locked_down())
                return -EPERM;
 
        if (fpriv->mmap_state == pci_mmap_io)

diff --git a/drivers/pci/syscall.c b/drivers/pci/syscall.c
index 9bf993e1f71e837faebe8227accb6a7225a3d7cc..c09524738ceba602dc1883ea17e121d48884c000 100644 (file)
--- a/drivers/pci/syscall.c
+++ b/drivers/pci/syscall.c
@@ -92,7 +92,7 @@ SYSCALL_DEFINE5(pciconfig_write, unsigned long, bus, unsigned long, dfn,
        u32 dword;
        int err = 0;
 
-       if (!capable(CAP_SYS_ADMIN))
+       if (!capable(CAP_SYS_ADMIN) || kernel_is_locked_down())
                return -EPERM;
 
        dev = pci_get_bus_and_slot(bus, dfn);