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Date:   Wed, 13 Nov 2019 02:29:06 +0000
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Aleksa Sarai <cyphar@cyphar.com>
Cc:     Jeff Layton <jlayton@kernel.org>,
        "J. Bruce Fields" <bfields@fieldses.org>,
        Arnd Bergmann <arnd@arndb.de>,
        David Howells <dhowells@redhat.com>,
        Shuah Khan <shuah@kernel.org>,
        Shuah Khan <skhan@linuxfoundation.org>,
        Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Christian Brauner <christian@brauner.io>,
        Eric Biederman <ebiederm@xmission.com>,
        Andy Lutomirski <luto@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Kees Cook <keescook@chromium.org>,
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        David Drysdale <drysdale@google.com>,
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        Oleg Nesterov <oleg@redhat.com>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>,
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Subject: Re: [PATCH v15 7/9] open: introduce openat2(2) syscall
Message-ID: <20191113022906.GD26530@ZenIV.linux.org.uk>
References: <20191105090553.6350-1-cyphar@cyphar.com>
 <20191105090553.6350-8-cyphar@cyphar.com>
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On Tue, Nov 05, 2019 at 08:05:51PM +1100, Aleksa Sarai wrote:
  
> +/*
> + * Arguments for how openat2(2) should open the target path. If @resolve is
> + * zero, then openat2(2) operates very similarly to openat(2).
> + *
> + * However, unlike openat(2), unknown bits in @flags result in -EINVAL rather
> + * than being silently ignored. @mode must be zero unless one of {O_CREAT,
> + * O_TMPFILE} are set, and @upgrade_mask must be zero unless O_PATH is set.
> + *
> + * @flags: O_* flags.
> + * @mode: O_CREAT/O_TMPFILE file mode.
> + * @upgrade_mask: UPGRADE_* flags (to restrict O_PATH re-opening).

???

> + * @resolve: RESOLVE_* flags.
> + */
> +struct open_how {
> +	__aligned_u64 flags;
> +	__u16 mode;
> +	__u16 __padding[3]; /* must be zeroed */
> +	__aligned_u64 resolve;
> +};