diff options
| author | Liu Hua <sdu.liu@huawei.com> | 2019-07-09 22:20:45 -0700 |
|---|---|---|
| committer | gVisor bot <gvisor-bot@google.com> | 2019-07-09 22:21:56 -0700 |
| commit | 7581e84cb6b709019c51a1e7d86414f696470554 (patch) | |
| tree | 3d3f83615896429df1a0dd52b6d271518d2b2bf6 /pkg/sentry/platform | |
| parent | 7965b1272bb0579da47960e64ea902c74f49483d (diff) | |
tss: block userspace access to all I/O ports.
A userspace process (CPL=3) can access an i/o port if the bit corresponding to
the port is set to 0 in the I/O permission bitmap.
Configure the I/O permission bitmap address beyond the last valid byte in the
TSS so access to all i/o ports is blocked.
Signed-off-by: Liu Hua <sdu.liu@huawei.com>
Change-Id: I3df76980c3735491db768f7210e71703f86bb989
PiperOrigin-RevId: 257336518
Diffstat (limited to 'pkg/sentry/platform')
| -rw-r--r-- | pkg/sentry/platform/ring0/kernel_amd64.go | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/pkg/sentry/platform/ring0/kernel_amd64.go b/pkg/sentry/platform/ring0/kernel_amd64.go index 3577b5127..0feff8778 100644 --- a/pkg/sentry/platform/ring0/kernel_amd64.go +++ b/pkg/sentry/platform/ring0/kernel_amd64.go @@ -70,6 +70,14 @@ func (c *CPU) init() { c.tss.ist1Lo = uint32(stackAddr) c.tss.ist1Hi = uint32(stackAddr >> 32) + // Set the I/O bitmap base address beyond the last byte in the TSS + // to block access to the entire I/O address range. + // + // From section 18.5.2 "I/O Permission Bit Map" from Intel SDM vol1: + // I/O addresses not spanned by the map are treated as if they had set + // bits in the map. + c.tss.ioPerm = tssLimit + 1 + // Permanently set the kernel segments. c.registers.Cs = uint64(Kcode) c.registers.Ds = uint64(Kdata) |