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    SubjectRe: [RFC,PATCH 1/2] seccomp_filters: system call filtering using BPF
    On 01/12, 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?
    >
    > Maybe I don't understand this correctly.

    May be this needs something like LSM_UNSAFE_SECCOMP, or perhaps
    cap_bprm_set_creds() should take seccomp.mode == 2 into account, I dunno.

    OTOH, currently seccomp.mode == 1 doesn't allow to exec at all.

    Oleg.



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