lkml.org 
[lkml]   [2022]   [Feb]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [PATCH V2 19/32] x86/sgx: Support adding of pages to an initialized enclave
    From
    Hi Jarkko,

    On 2/20/2022 10:40 AM, Jarkko Sakkinen wrote:
    ...

    > Do you know if it is possible to do EAUG, EMODPR and the do a single
    > EACCEPT for both? Just looking at pseudo-code, it looked doable but
    > I need to check this.
    >
    > I.e. EAUG has this
    >
    > EPCM(DS:RCX).BLOCKED := 0;
    > EPCM(DS:RCX).PENDING := 1;
    > EPCM(DS:RCX).MODIFIED := 0;
    > EPCM(DS:RCX).PR := 0;
    > (* associate the EPCPAGE with the SECS by storing the SECS identifier of DS:TMP_SECS *)
    > Update EPCM(DS:RCX) SECS identifier to reference DS:TMP_SECS identifier;
    > (* Set EPCM valid fields *)
    > EPCM(DS:RCX).VALID := 1;
    >
    > And EMODPR only checks .VALID.

    After that check there is also:
    IF (EPCM(DS:RCX).PENDING is not 0 or (EPCM(DS:RCX).MODIFIED is not 0) )
    THEN
    RFLAGS.ZF := 1;
    RAX := SGX_PAGE_NOT_MODIFIABLE;
    GOTO DONE;
    FI;

    Attempting the SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS ioctl() on a recently
    added page (EAUG) that has not yet been EACCEPTed is thus expected to fail
    with errno of EFAULT (indicating ENCLS[EMODPR] failure) and the returned
    structure's result field set to 20 (SGX_PAGE_NOT_MODIFIABLE).

    I confirmed this behavior by modifying the "augment" kselftest test by adding
    a SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS call between the new memory access and
    the EACCEPT.

    Reinette

    \
     
     \ /
      Last update: 2022-02-22 20:19    [W:2.224 / U:0.332 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site