Re: 2001_05_09 patch against 2.4.4

From: Chris Evans (chrisat_private)
Date: Thu May 10 2001 - 14:58:54 PDT

  • Next message: jmjonesat_private: "Re: 2001_05_09 patch against 2.4.4"

    On Wed, 9 May 2001, Chris Wright wrote:
    > Latest lsm patch is available.
    Found the time for a quick look at "security.h" within this patch.
    Comments follow.
    1) I didn't see any explict hook for file opening. I see
    file_ops->alloc_security, but that seems to be something else. (also it
    does not allow a security module to return other than EACCES. For
    prevention of covert channels, you might want to return ENOENT even if
    the file exists)
    2) I see, currently, that syscalls are not hooked in a generic manner.
    From exceptionally brief scanning of the archives, this seems to be a
    debated point.
    Are there plans to hook syscalls? If not, I can make a very strong
    argument to do so. Let me know if you want to hear it.
    3) There's a problem brewing with regards lack of central control points
    for logically equivalent operations.
    For example, in file_security_ops, I see separate hooks for mmap, read,
    write, readv, writev. But, logically, mmap(..., PROT_WRITE,
    MAP_SHARED, ...) is equivalent to write().
    Lack of central control may result in a module blocking access to some
    operation, but leave a "backdoor" where the same operation is let through
    by a different syscall sequence to achieve the same effect.
    linux-security-module mailing list

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