On Thu, Jul 16, 2020 at 04:52:50PM +0300, Jarkko Sakkinen wrote:
Just minor things below - I'm not even going to pretend I fully
understand what's going on but FWICT, it looks non-threateningly ok to
me.
> diff --git a/arch/x86/kernel/cpu/sgx/driver.c b/arch/x86/kernel/cpu/sgx/driver.c
> new file mode 100644
> index 000000000000..b52520407f5b
> --- /dev/null
> +++ b/arch/x86/kernel/cpu/sgx/driver.c
> @@ -0,0 +1,177 @@
> +// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
> +// Copyright(c) 2016-18 Intel Corporation.
> +
> +#include <linux/acpi.h>
> +#include <linux/miscdevice.h>
> +#include <linux/mman.h>
> +#include <linux/security.h>
> +#include <linux/suspend.h>
> +#include <asm/traps.h>
> +#include "driver.h"
> +#include "encl.h"
> +
> +MODULE_DESCRIPTION("Intel SGX Enclave Driver");
> +MODULE_AUTHOR("Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>");
> +MODULE_LICENSE("Dual BSD/GPL");
That boilerplate stuff usually goes to the end of the file.
...
> +static struct sgx_encl_page *sgx_encl_load_page(struct sgx_encl *encl,
> + unsigned long addr)
> +{
> + struct sgx_encl_page *entry;
> + unsigned int flags;
> +
> + /* If process was forked, VMA is still there but vm_private_data is set
> + * to NULL.
> + */
> + if (!encl)
> + return ERR_PTR(-EFAULT);
> +
> + flags = atomic_read(&encl->flags);
> +
^ Superfluous newline.
> + if ((flags & SGX_ENCL_DEAD) || !(flags & SGX_ENCL_INITIALIZED))
> + return ERR_PTR(-EFAULT);
> +
> + entry = xa_load(&encl->page_array, PFN_DOWN(addr));
> + if (!entry)
> + return ERR_PTR(-EFAULT);
> +
> + /* Page is already resident in the EPC. */
> + if (entry->epc_page)
> + return entry;
> +
> + return ERR_PTR(-EFAULT);
> +}
> +
> +static void sgx_mmu_notifier_release(struct mmu_notifier *mn,
> + struct mm_struct *mm)
> +{
> + struct sgx_encl_mm *encl_mm =
> + container_of(mn, struct sgx_encl_mm, mmu_notifier);
Just let it stick out.
> + struct sgx_encl_mm *tmp = NULL;
> +
> + /*
> + * The enclave itself can remove encl_mm. Note, objects can't be moved
> + * off an RCU protected list, but deletion is ok.
> + */
> + spin_lock(&encl_mm->encl->mm_lock);
> + list_for_each_entry(tmp, &encl_mm->encl->mm_list, list) {
> + if (tmp == encl_mm) {
> + list_del_rcu(&encl_mm->list);
> + break;
> + }
> + }
> + spin_unlock(&encl_mm->encl->mm_lock);
> +
> + if (tmp == encl_mm) {
> + synchronize_srcu(&encl_mm->encl->srcu);
> + mmu_notifier_put(mn);
> + }
> +}
> +
> +static void sgx_mmu_notifier_free(struct mmu_notifier *mn)
> +{
> + struct sgx_encl_mm *encl_mm =
> + container_of(mn, struct sgx_encl_mm, mmu_notifier);
Ditto.
...
> +/**
> + * sgx_encl_may_map() - Check if a requested VMA mapping is allowed
> + * @encl: an enclave
> + * @start: lower bound of the address range, inclusive
> + * @end: upper bound of the address range, exclusive
> + * @vm_prot_bits: requested protections of the address range
> + *
> + * Iterate through the enclave pages contained within [@start, @end) to verify
> + * the permissions requested by @vm_prot_bits do not exceed that of any enclave
> + * page to be mapped.
> + *
> + * Return:
> + * 0 on success,
> + * -EACCES if VMA permissions exceed enclave page permissions
> + */
> +int sgx_encl_may_map(struct sgx_encl *encl, unsigned long start,
> + unsigned long end, unsigned long vm_flags)
> +{
> + unsigned long vm_prot_bits = vm_flags & (VM_READ | VM_WRITE | VM_EXEC);
> + unsigned long idx_start = PFN_DOWN(start);
> + unsigned long idx_end = PFN_DOWN(end - 1);
> + struct sgx_encl_page *page;
> + XA_STATE(xas, &encl->page_array, idx_start);
> +
> + /*
> + * Disallow RIE tasks as their VMA permissions might conflict with the
"RIE", hmm what is that?
/me looks at the test
Aaah, READ_IMPLIES_EXEC. Is "RIE" some widely accepted acronym I'm not
aware of?
> + * enclave page permissions.
> + */
> + if (!!(current->personality & READ_IMPLIES_EXEC))
The "!!" is not really needed - you're in boolean context.
...
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
