On Mon, May 03, 2021 at 09:39:05AM -0700, Dave Hansen wrote: > On 5/3/21 8:41 AM, Jarkko Sakkinen wrote: > >> $ ls -l /dev/sgx_enclave > >> crw------- 1 dave dave 10, 125 Apr 28 11:32 /dev/sgx_enclave > >> $ ./test_sgx > >> 0x0000000000000000 0x0000000000002000 0x03 > >> 0x0000000000002000 0x0000000000001000 0x05 > >> 0x0000000000003000 0x0000000000003000 0x03 > >> SUCCESS > >> > >> *But*, is that OK? Should we be happily creating a PROT_EXEC mapping on > >> a ugo-x file? Why were we respecting noexec on the filesystem but not > >> ugo-x on the file? > > Yeah, this supports my earlier response: > > > > "EPERM The prot argument asks for PROT_EXEC but the mapped area > > belongs to a file on a filesystem that was mounted no-exec." > > https://man7.org/linux/man-pages/man2/mmap.2.html > > > > I guess the right model is to think just as "anonymous memory" > > with equivalent access control semantics after succesfully > > opened for read and write. > > I guess I'll answer my own question: The "x" bit on file permissions > really only controls the ability for the file to be execve()'d, but has > no bearing on the ability for an executable *mapping* to be created. > This is existing VFS behavior and is not specific to SGX. Yeah, that's nicely put it into one sentence :-) > I think I'll just send a patch to pull that warning out. /Jarkko
