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    SubjectRe: Secure-linux and standard kernel
    Date
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    On Thu, June 25 1998, Chris Evans <chris@ferret.lmh.ox.ac.uk> wrote:
    |
    |On Thu, 25 Jun 1998, MOLNAR Ingo wrote:
    |
    |> if 'ping' is setuid root and the first thing say ping.c does is:
    |>
    |> drop_cap(ALL_BUT_RAWSOCKET);
    |
    |Yes this is good isn't it. Note that traceroute's a better example; ping
    |for linux already does:
    |
    |main()
    |fd = socket(SOCK_RAW ...)
    |setuid(getuid());
    |
    |
    |
    |rlogin, rsh, dump, restore, even lpr, lprm, lpq, etc. all benefit a
    |similar way with
    |
    |drop_cap(ALL_BUT_BIND_TO_LOW_PORT);

    I really don't like this idea. It's certainly easier to implement than the
    "nice" way, and maybe its good in the mean time, but it would require:

    1. maintenance of separate source code for linux binaries (or asking the
    "upstream maintainers" to insert this code)

    2. reliance on the binary for behaving well - what if someone breaks in and
    changes the binary not to call this?

    3. the admin can't control things in an administrative way

    I think a more "generic" solution would be to attach access control to
    sockets, e.g. have /dev/tcp/1-65535, /dev/raw/, /dev/udp, /dev/icmp
    (?) as special device files (only creat inodes for sockets with
    special access control) and set the owner/group/premissions like any
    other file. If such a file exists then use its permissions, if not
    then resort back to the standard method (root-only for raw and TCP/UDP
    sockets less than 1024, open for everyone else (?) on other sockets)

    You can even link the same i-node with all ports with identical access
    permissions to save inode consumption.

    What do you think?

    Cheers,

    --Amos

    --Amos Shapira | "Of course Australia was marked for
    133 Shlomo Ben-Yosef st. | glory, for its people had been chosen
    Jerusalem 93 805 | by the finest judges in England."
    ISRAEL amos@gezernet.co.il | -- Anonymous

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