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    Subject[PATCH 46/50] perf: Disable monitoring on setuid processes for regular users
    Date
    3.5.7.16 -stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Stephane Eranian <eranian@google.com>

    commit 2976b10f05bd7f6dab9f9e7524451ddfed656a89 upstream.

    There was a a bug in setup_new_exec(), whereby
    the test to disabled perf monitoring was not
    correct because the new credentials for the
    process were not yet committed and therefore
    the get_dumpable() test was never firing.

    The patch fixes the problem by moving the
    perf_event test until after the credentials
    are committed.

    Signed-off-by: Stephane Eranian <eranian@google.com>
    Tested-by: Jiri Olsa <jolsa@redhat.com>
    Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
    ---
    fs/exec.c | 16 +++++++++-------
    1 file changed, 9 insertions(+), 7 deletions(-)

    diff --git a/fs/exec.c b/fs/exec.c
    index 5a76464..832763a 100644
    --- a/fs/exec.c
    +++ b/fs/exec.c
    @@ -1162,13 +1162,6 @@ void setup_new_exec(struct linux_binprm * bprm)
    set_dumpable(current->mm, suid_dumpable);
    }

    - /*
    - * Flush performance counters when crossing a
    - * security domain:
    - */
    - if (!get_dumpable(current->mm))
    - perf_event_exit_task(current);
    -
    /* An exec changes our domain. We are no longer part of the thread
    group */

    @@ -1232,6 +1225,15 @@ void install_exec_creds(struct linux_binprm *bprm)

    commit_creds(bprm->cred);
    bprm->cred = NULL;
    +
    + /*
    + * Disable monitoring for regular users
    + * when executing setuid binaries. Must
    + * wait until new credentials are committed
    + * by commit_creds() above
    + */
    + if (get_dumpable(current->mm) != SUID_DUMP_USER)
    + perf_event_exit_task(current);
    /*
    * cred_guard_mutex must be held at least to this point to prevent
    * ptrace_attach() from altering our determination of the task's
    --
    1.8.1.2


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