Re: [PATCH v6 4/5] seccomp: add support for passing fds via USER_NOTIF
From: Jann Horn <jannh@google.com>
Date: 2018-09-06 16:15:49
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On Thu, Sep 6, 2018 at 5:29 PM Tycho Andersen [off-list ref] wrote:
The idea here is that the userspace handler should be able to pass an fd back to the trapped task, for example so it can be returned from socket().
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diff --git a/Documentation/userspace-api/seccomp_filter.rst b/Documentation/userspace-api/seccomp_filter.rst index d1498885c1c7..1c0aab306426 100644 --- a/Documentation/userspace-api/seccomp_filter.rst +++ b/Documentation/userspace-api/seccomp_filter.rst@@ -235,6 +235,9 @@ The interface for a seccomp notification fd consists of two structures: __u64 id; __s32 error; __s64 val; + __u8 return_fd; + __u32 fd; + __u32 fd_flags;
Normally, syscalls that take an optional file descriptor accept a signed 32-bit number, with -1 standing for "no file descriptor". Is there a reason why this uses a separate variable to signal whether an fd was provided? Apart from that, this patch looks good to me.