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    SubjectRe: [PATCH v7 04/11] task_isolation: provide strict mode configurable signal
    On Mon, Sep 28, 2015 at 11:17 AM, Chris Metcalf <cmetcalf@ezchip.com> wrote:
    > Allow userspace to override the default SIGKILL delivered
    > when a task_isolation process in STRICT mode does a syscall
    > or otherwise synchronously enters the kernel.
    >
    > In addition to being able to set the signal, we now also
    > pass whether or not the interruption was from a syscall in
    > the si_code field of the siginfo.
    >
    > Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
    > ---
    > include/uapi/linux/prctl.h | 2 ++
    > kernel/isolation.c | 17 +++++++++++++----
    > 2 files changed, 15 insertions(+), 4 deletions(-)
    >
    > diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
    > index 2b8038b0d1e1..a5582ace987f 100644
    > --- a/include/uapi/linux/prctl.h
    > +++ b/include/uapi/linux/prctl.h
    > @@ -202,5 +202,7 @@ struct prctl_mm_map {
    > #define PR_GET_TASK_ISOLATION 49
    > # define PR_TASK_ISOLATION_ENABLE (1 << 0)
    > # define PR_TASK_ISOLATION_STRICT (1 << 1)
    > +# define PR_TASK_ISOLATION_SET_SIG(sig) (((sig) & 0x7f) << 8)
    > +# define PR_TASK_ISOLATION_GET_SIG(bits) (((bits) >> 8) & 0x7f)
    >
    > #endif /* _LINUX_PRCTL_H */
    > diff --git a/kernel/isolation.c b/kernel/isolation.c
    > index 3779ba670472..44bafcd08bca 100644
    > --- a/kernel/isolation.c
    > +++ b/kernel/isolation.c
    > @@ -77,14 +77,23 @@ void task_isolation_enter(void)
    > }
    > }
    >
    > -static void kill_task_isolation_strict_task(void)
    > +static void kill_task_isolation_strict_task(int is_syscall)
    > {
    > + siginfo_t info = {};
    > + int sig;
    > +
    > /* RCU should have been enabled prior to this point. */
    > RCU_LOCKDEP_WARN(!rcu_is_watching(), "kernel entry without RCU");
    >
    > dump_stack();
    > current->task_isolation_flags &= ~PR_TASK_ISOLATION_ENABLE;
    > - send_sig(SIGKILL, current, 1);
    > +
    > + sig = PR_TASK_ISOLATION_GET_SIG(current->task_isolation_flags);
    > + if (sig == 0)
    > + sig = SIGKILL;
    > + info.si_signo = sig;
    > + info.si_code = is_syscall;

    I think this needs real SI_ defines.

    > + send_sig_info(sig, &info, current);
    > }
    >
    > /*
    > @@ -103,7 +112,7 @@ void task_isolation_syscall(int syscall)
    >
    > pr_warn("%s/%d: task_isolation strict mode violated by syscall %d\n",
    > current->comm, current->pid, syscall);
    > - kill_task_isolation_strict_task();
    > + kill_task_isolation_strict_task(1);

    No magic numbers please.

    --Andy


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