Message ID | 149141232449.31282.15045536717220570492.stgit@warthog.procyon.org.uk (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
On Wed, Apr 5, 2017 at 10:12 AM, David Howells <dhowells@redhat.com> wrote: > From: Matthew Garrett <matthew.garrett@nebula.com> > > Writing to MSRs should not be allowed if the kernel is locked down, since > it could lead to execution of arbitrary code in kernel mode. Based on a > patch by Kees Cook. > > Cc: Kees Cook <keescook@chromium.org> > Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com> > Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Kees Cook <keescook@chromium.org> -Kees > --- > > arch/x86/kernel/msr.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c > index ef688804f80d..fbcce028e502 100644 > --- a/arch/x86/kernel/msr.c > +++ b/arch/x86/kernel/msr.c > @@ -84,6 +84,9 @@ static ssize_t msr_write(struct file *file, const char __user *buf, > int err = 0; > ssize_t bytes = 0; > > + if (kernel_is_locked_down()) > + return -EPERM; > + > if (count % 8) > return -EINVAL; /* Invalid chunk size */ > > @@ -131,6 +134,10 @@ static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg) > err = -EBADF; > break; > } > + if (kernel_is_locked_down()) { > + err = -EPERM; > + break; > + } > if (copy_from_user(®s, uregs, sizeof regs)) { > err = -EFAULT; > break; >
diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c index ef688804f80d..fbcce028e502 100644 --- a/arch/x86/kernel/msr.c +++ b/arch/x86/kernel/msr.c @@ -84,6 +84,9 @@ static ssize_t msr_write(struct file *file, const char __user *buf, int err = 0; ssize_t bytes = 0; + if (kernel_is_locked_down()) + return -EPERM; + if (count % 8) return -EINVAL; /* Invalid chunk size */ @@ -131,6 +134,10 @@ static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg) err = -EBADF; break; } + if (kernel_is_locked_down()) { + err = -EPERM; + break; + } if (copy_from_user(®s, uregs, sizeof regs)) { err = -EFAULT; break;