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    SubjectRe: [RFC,PATCH 1/2] seccomp_filters: system call filtering using BPF
    Steven Rostedt wrote:
    > On Wed, 2012-01-11 at 11:25 -0600, Will Drewry wrote:
    > > Filter programs may _only_ cross the execve(2) barrier if last filter
    > > program was attached by a task with CAP_SYS_ADMIN capabilities in its
    > > user namespace. Once a task-local filter program is attached from a
    > > process without privileges, execve will fail. This ensures that only
    > > privileged parent task can affect its privileged children (e.g., setuid
    > > binary).
    > This means that a non privileged user can not run another program with
    > limited features? How would a process exec another program and filter
    > it? I would assume that the filter would need to be attached first and
    > then the execv() would be performed. But after the filter is attached,
    > the execv is prevented?

    Ugly method: Using ptrace(), trap after the execve() and issue fake
    syscalls to install the filter. I feel dirty thinking it, in a good way.

    LD_PRELOAD has been suggested. It's not 100% reliable because not all
    executables are dynamic (on some uClinux platforms none of them are),
    but it will usually work.

    -- Jamie

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