On Mon, Aug 19, 2019 at 06:25:44PM +0300, Jarkko Sakkinen wrote:
> vm_prot_bits is very bad and misleading name for the field in struct
> sgx_encl_page. What the field contains exactly is not @prot of
> mprotect() but the *maximum* VM flags for the VMA that contains the
> given enclave page.
>
> Thus, the only viable name for the field is max_vm_flags. In functions
> that also pass VM flags the parameter name is renamed from vm_prot_bits
> to vm_flags.
Why not max_vm_prot_bits? 'vm_flags' implies the field contains all
manner of VM_FLAGS. The 'vm_prot_bits' name was derived from
calc_vm_prot_bits() to provide this differentiation, especially since
there's also a calc_vm_flag_bits(),
> To summarize, this commit makes two improvements to clarify the
> permission handling:
>
> 1. Changes the name to match better the contents.
> 2. Uses naming to differentiate the field inside the struct and
> the parameter passed to functions.
>
> Cc: Sean Christopherson <sean.j.christpherson@xxxxxxxxx>
> Cc: Shay Katz-zamir <shay.katz-zamir@xxxxxxxxx>
> Cc: Serge Ayoun <serge.ayoun@xxxxxxxxx>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
> ---
> arch/x86/kernel/cpu/sgx/driver/ioctl.c | 2 +-
> arch/x86/kernel/cpu/sgx/encl.c | 14 +++++++-------
> arch/x86/kernel/cpu/sgx/encl.h | 4 ++--
> 3 files changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/sgx/driver/ioctl.c b/arch/x86/kernel/cpu/sgx/driver/ioctl.c
> index 2415dcb20a6e..b61e06daad6e 100644
> --- a/arch/x86/kernel/cpu/sgx/driver/ioctl.c
> +++ b/arch/x86/kernel/cpu/sgx/driver/ioctl.c
> @@ -261,7 +261,7 @@ static struct sgx_encl_page *sgx_encl_page_alloc(struct sgx_encl *encl,
> encl_page->encl = encl;
>
> /* Calculate maximum of the VM flags for the page. */
> - encl_page->vm_prot_bits = calc_vm_prot_bits(prot, 0);
> + encl_page->max_vm_flags = calc_vm_prot_bits(prot, 0);
>
> ret = radix_tree_insert(&encl->page_tree, PFN_DOWN(encl_page->desc),
> encl_page);
> diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
> index a20d498e9dcd..890eacb45a80 100644
> --- a/arch/x86/kernel/cpu/sgx/encl.c
> +++ b/arch/x86/kernel/cpu/sgx/encl.c
> @@ -292,25 +292,25 @@ static unsigned int sgx_vma_fault(struct vm_fault *vmf)
> * @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
> + * @vm_flags: requested VM flags for 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. Page addresses that do not have an associated enclave
> - * page are interpreted to zero permissions.
> + * the the VM flags do not exceed that of any enclave page to be mapped. Page
> + * addresses that do not have an associated enclave page are interpreted to zero
> + * permissions.
> *
> * 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_prot_bits)
> + unsigned long end, unsigned long vm_flags)
If 'vm_prot_bits' is distasteful, 'prot' would be preferrable as its used
throughout the kernel for variable that hold only the prot bits.
> {
> unsigned long idx, idx_start, idx_end;
> struct sgx_encl_page *page;
>
> /* PROT_NONE always succeeds. */
> - if (!vm_prot_bits)
> + if (!vm_flags)
> return 0;
>
> idx_start = PFN_DOWN(start);
> @@ -321,7 +321,7 @@ int sgx_encl_may_map(struct sgx_encl *encl, unsigned long start,
> page = radix_tree_lookup(&encl->page_tree, idx);
> mutex_unlock(&encl->lock);
>
> - if (!page || (~page->vm_prot_bits & vm_prot_bits))
> + if (!page || (~page->max_vm_flags & vm_flags))
> return -EACCES;
> }
>
> diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h
> index d3a1687ed84c..0e28b784a8c5 100644
> --- a/arch/x86/kernel/cpu/sgx/encl.h
> +++ b/arch/x86/kernel/cpu/sgx/encl.h
> @@ -44,7 +44,7 @@ enum sgx_encl_page_desc {
>
> struct sgx_encl_page {
> unsigned long desc;
> - unsigned long vm_prot_bits;
> + unsigned long max_vm_flags;
> struct sgx_epc_page *epc_page;
> struct sgx_va_page *va_page;
> struct sgx_encl *encl;
> @@ -134,6 +134,6 @@ void sgx_free_va_slot(struct sgx_va_page *va_page, unsigned int offset);
> bool sgx_va_page_full(struct sgx_va_page *va_page);
>
> int sgx_encl_may_map(struct sgx_encl *encl, unsigned long start,
> - unsigned long end, unsigned long vm_prot_bits);
> + unsigned long end, unsigned long vm_flags);
>
> #endif /* _X86_ENCL_H */
> --
> 2.20.1
>
