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    SubjectRe: /proc/<pid>/mem unreadable (was strace and linux 1.3.97)
    Date
    In article <96May3.101144+0100met_dst.2218-305+20@work.smurf.noris.de>,
    Matthias Urlichs <smurf@smurf.noris.de> wrote:
    >In linux.dev.kernel, article <199605021038.FAA16498@caffeine.io.com>,
    > "James H. Cloos Jr." <cloos@jhcloos.com> writes:
    >>
    >> Seems to me that the answer, then, is to have /prov/<pid>/mem mod 600
    >> and owned by the euid of the process, rather than owned by the uid
    >> that ran it. Linus?
    >>
    >No, that woon't work, for when the setuid program does a
    >seteuid(getuid())
    >exec(user_program)
    >
    >it's still vulnerable between these two calls.
    >
    >The _only_ workable solution for this is to invalidate the /proc/###/mem
    >inode when the process in question calls exec().

    As you might have seen, it is fixed in 1.3.98. Access to /proc/###/mem
    is only allowed if the process has been PTRACE_ATTACHed to by the
    process that tries to read/write/mmap to it.

    Mike.
    --
    + Miquel van Smoorenburg + Cistron Internet Services + Living is a |
    | miquels@cistron.nl (SP6) | Independent Dutch ISP | horizontal |
    + miquels@drinkel.ow.org + http://www.cistron.nl/ + fall +



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