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Problem Report 0338 Details

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Report 0338 Actions

    Problem Report Number 0338
    Submitter's Classification Specification problem
    State Resolved
    Resolution Permanent Interpretation (PIN)
    Problem Resolution ID PIN.X.0054
    Raised 1995-12-07 08:00
    Updated 2003-03-13 08:00
    Published 1995-12-14 08:00
    Product Standard Internationalised System Calls and Libraries (XPG4)
    Certification Program The Open Brand certification program
    Test Suite VSX4 version 4.3.5
    Test Identification ANSI.os/streamio/tmpfile 2
    Specification System Interfaces and Headers Issue 4
    Location in Spec See Problem Text
    Problem Summary PIN4.054 The test asserts the mode of a file whose name is visible only between an open() and an immediate unlink() . Our implementation restricts the mode so as to close a possible security hole. The attached...
    Problem Text

    The test asserts the mode of a file whose name is visible
    only between an open() and an immediate unlink() . Our implementation
    restricts the mode so as to close a possible security hole.
    The attached IEEE POSIX 1003.1-90 Interpretation indicates that our
    behaviour is conforming and that there
    is a contradiction between the Test methods standard and the Base
    standard.

    _____________________________________________________________________________
    (c) 1995 by the Institute of Electrical and Electronics Engineers Inc.
    All Rights Reserved. Not to be published in full or in part
    without prior written permission from the IEEE.

    PASC Interpretation reference
    1003.1-90 #74

    _____________________________________________________________________________

    Interpretation Number: XXXX
    Topic: tmpfile
    Relevant Sections: 8.2.3.9
    Classification:


    Interpretation Request:
    -----------------------

    This is a request for interpretation of IEEE standard 1003.1-1990 (ISO
    9945-1:1990)


    Section 8.2.3.9 tmpfile(), line 398-399 describes the tmpfile()
    function as "tmpfile() shall allocate a file descriptor as fopen() does".

    The fopen() descriptions states "The fopen() function shall allocate
    a file descriptor as open() does".

    Many common implementations return a file descriptor for an unlinked file.
    Is it conforming for tmpfile() to call open() with a mode of zero, so
    that the temporary file created in the file namespace prior to
    unlinking be protected from access by other users ?

    POSIX 2003.1 has an assertion 8.2.3.9-05(B) that would say
    that it is not conforming; the assertion states:

    "When a call to tmpfile() creates a file, then the file permission bits
    are set to allow both reading and writing for owner, for group, and
    for other users except for those bits set in the process's file mode
    creation mask. No execute (search) permission bits are set. The user
    ID of the file is set to the process's effective user ID and the group
    ID of the file is set to the process's effective group ID or to the
    group owner of its parent directory."


    This assertion relates to the references between tmpfile() -> fopen() -> open().
    It appears to us that this requirement is beyond the specification in
    P1003.1 for tmpfile() which is to allocate a file descriptor and that this
    requirement in P2003.1 should be noted as incorrect.



    IEEE Interpretation for 1003.1-1990 (1003.1-90 #74)
    -----------------------------------
    Yes it is conforming. The standard clearly does not require a
    particular implementation of tmpfile(), just that
    a file descriptor be allocated.

    This is a conflict between the P1003.1 base standard and the P2003.1
    test method standard. The test method standard clearly indicates that a
    conforming test suite is required to test this, however the base
    standard indicates that a conforming implementation may fail such a test.
    This situation is being referred to the sponsor(s).

    Rationale for Interpretation:
    -----------------------------
    None.
    Forwarded to Interpretation group: Aug 30 1995
    Resolution forwarded for review: Oct 18 1995
    Finalised: Nov 21 1995


    Test Output
    ************************************************************************
    /tset/ANSI.os/streamio/tmpfile/T.tmpfile 2 Failed

    Test Description:
    When a call to tmpfile() creates a file, then the file permission bits
    are set to allow both reading and writing for owner, for group, and
    for other users except for those bits set in the process's file mode
    creation mask. No execute (search) permission bits are set. The user
    ID of the file is set to the process's effective user ID and the group
    ID of the file is set to the process's effective group ID or to the
    group owner of its parent directory
    Posix Ref: Component TMPFILE Assertion 8.2.3.9-05(B)

    Test Strategy:
    CREATE child process
    EXECUTE new program
    SUBPROGRAM:
    CREATE a temporary file using tmpfile()
    OBTAIN file descriptor for stream using fileno()
    VERIFY mode and owner of file are as expected, using fstat()
    CLOSE stream using fclose()
    RESET the file creation mask
    CREATE a temporary file using tmpfile()
    OBTAIN file descriptor for stream using fileno()
    SET all bits in the file protection mask for this process
    VERIFY mode and owner of file are as expected, using fstat()
    CLOSE stream using fclose()

    Test Information:
    tmpfile() did not creat file with mode 0666 when umask was set to 0,
    found 0
    ************************************************************************

    Review Information

    Review Type TSMA Review
    Start Date null
    Completed null
    Status Complete
    Review Recommendation No Resolution Given
    Review Response
    In the light of the interpretation of the IEEE 1003.1 standard it is recommended
    that a permanent interpretation is granted.

    Review Type SA Review
    Start Date null
    Completed null
    Status Complete
    Review Resolution Permanent Interpretation (PIN)
    Review Conclusion
    A Permanent Interpretation is granted.

    Problem Reporting System Options:

     

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