On Mon, Mar 07, 2022 at 05:35:04PM +0200, Jarkko Sakkinen wrote: > vm_max_permissions was created to control the pre-initialization content > that contributes to MRSIGNATURE. It was never meant to be as a limit to > dynamically added pages. > > E.g. static content could be used as a hook for LSM's to decide whether > certain signature is qualified for EINIT. Dynamic content has nothing to > do with that. The current mechanisms only add to the complexity on how > to control PTE and EPCM permissions, and do not add anything else than > obfuscity to security side of things. > > Thus add PROT_EXEC to the permissions assigned by the #PF handler. > > Signed-off-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx> > --- > arch/x86/kernel/cpu/sgx/encl.c | 9 ++++----- > 1 file changed, 4 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c > index 79e39bd99c09..0256918b2c2f 100644 > --- a/arch/x86/kernel/cpu/sgx/encl.c > +++ b/arch/x86/kernel/cpu/sgx/encl.c > @@ -160,12 +160,11 @@ static vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma, > encl_page->encl = encl; > > /* > - * Adding a regular page that is architecturally allowed to only > - * be created with RW permissions. > - * TBD: Interface with user space policy to support max permissions > - * of RWX. > + * Dynamic pages do not contribute to MRSIGNATURE, i.e. they are > + * controlled only by PTE and EPCM permissions. Thus, the no limit > + * is set here. > */ > - prot = PROT_READ | PROT_WRITE; > + prot = PROT_READ | PROT_WRITE | PROT_EXEC; > encl_page->vm_run_prot_bits = calc_vm_prot_bits(prot, 0); > encl_page->vm_max_prot_bits = encl_page->vm_run_prot_bits; > > -- > 2.35.1 > This is really a show stopper. I think here's a logical mistake on for what purpose vm_max_prot_bits are used for. They are meant for the static and also signed content of the enclave. These changes in the patch set that are related to vm_max_prot_bits only messes up what already exists, and make incredibly hard to implement anything decent on top of SGX2 features. BR, Jarkko
