On Fri, Nov 13, 2020 at 10:25:43AM +0000, Mel Gorman wrote: > On Fri, Nov 13, 2020 at 12:01:21AM +0200, Jarkko Sakkinen wrote: > > From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx> > > > > Background > > ========== > > > > 1. SGX enclave pages are populated with data by copying from normal memory > > via ioctl() (SGX_IOC_ENCLAVE_ADD_PAGES), which will be added later in > > this series. > > 2. It is desirable to be able to restrict those normal memory data sources. > > For instance, to ensure that the source data is executable before > > copying data to an executable enclave page. > > 3. Enclave page permissions are dynamic (just like normal permissions) and > > can be adjusted at runtime with mprotect(). > > > > This creates a problem because the original data source may have long since > > vanished at the time when enclave page permissions are established (mmap() > > or mprotect()). > > > > The solution (elsewhere in this series) is to force enclaves creators to > > declare their paging permission *intent* up front to the ioctl(). This > > intent can be immediately compared to the source data???s mapping and > > rejected if necessary. > > > > The ???intent??? is also stashed off for later comparison with enclave > > PTEs. This ensures that any future mmap()/mprotect() operations > > performed by the enclave creator or done on behalf of the enclave > > can be compared with the earlier declared permissions. > > > > Problem > > ======= > > > > There is an existing mmap() hook which allows SGX to perform this > > permission comparison at mmap() time. However, there is no corresponding > > ->mprotect() hook. > > > > Solution > > ======== > > > > Add a vm_ops->mprotect() hook so that mprotect() operations which are > > inconsistent with any page's stashed intent can be rejected by the driver. > > > > Cc: linux-mm@xxxxxxxxx > > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > > Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> > > Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> > > Acked-by: Jethro Beekman <jethro@xxxxxxxxxxxx> # v40 > > Acked-by: Dave Hansen <dave.hansen@xxxxxxxxx> # v40 > > # Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx> > > Co-developed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx> > > Signed-off-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx> > > Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Thank you. /Jarkko
