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    Subject[PATCH v2 2/2] uapi: split openat2(2) definitions from fcntl.h
    Date
    Florian mentioned that glibc doesn't use fcntl.h because it has some
    issues with namespace cleanliness, and that we should have a separate
    header for openat2(2) if possible. In addition, userspace has no real
    use for the OPEN_HOW_SIZE_* constants so move them to the in-kernel
    headers.

    Suggested-by: Florian Weimer <fweimer@redhat.com>
    Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
    ---
    MAINTAINERS | 1 +
    include/linux/fcntl.h | 4 ++++
    include/uapi/linux/fcntl.h | 36 +--------------------------------
    include/uapi/linux/openat2.h | 39 ++++++++++++++++++++++++++++++++++++
    4 files changed, 45 insertions(+), 35 deletions(-)
    create mode 100644 include/uapi/linux/openat2.h

    diff --git a/MAINTAINERS b/MAINTAINERS
    index bd5847e802de..737ada377ac3 100644
    --- a/MAINTAINERS
    +++ b/MAINTAINERS
    @@ -6397,6 +6397,7 @@ F: fs/*
    F: include/linux/fs.h
    F: include/linux/fs_types.h
    F: include/uapi/linux/fs.h
    +F: include/uapi/linux/openat2.h

    FINTEK F75375S HARDWARE MONITOR AND FAN CONTROLLER DRIVER
    M: Riku Voipio <riku.voipio@iki.fi>
    diff --git a/include/linux/fcntl.h b/include/linux/fcntl.h
    index f2eb05bd3af3..7bcdcf4f6ab2 100644
    --- a/include/linux/fcntl.h
    +++ b/include/linux/fcntl.h
    @@ -21,6 +21,10 @@
    (RESOLVE_NO_XDEV | RESOLVE_NO_MAGICLINKS | RESOLVE_NO_SYMLINKS | \
    RESOLVE_BENEATH | RESOLVE_IN_ROOT)

    +/* List of all open_how "versions". */
    +#define OPEN_HOW_SIZE_VER0 24 /* sizeof first published struct */
    +#define OPEN_HOW_SIZE_LATEST OPEN_HOW_SIZE_VER0
    +
    #ifndef force_o_largefile
    #define force_o_largefile() (!IS_ENABLED(CONFIG_ARCH_32BIT_OFF_T))
    #endif
    diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h
    index 5aaadfd79dd5..ca88b7bce553 100644
    --- a/include/uapi/linux/fcntl.h
    +++ b/include/uapi/linux/fcntl.h
    @@ -3,6 +3,7 @@
    #define _UAPI_LINUX_FCNTL_H

    #include <asm/fcntl.h>
    +#include <linux/openat2.h>

    #define F_SETLEASE (F_LINUX_SPECIFIC_BASE + 0)
    #define F_GETLEASE (F_LINUX_SPECIFIC_BASE + 1)
    @@ -100,39 +101,4 @@

    #define AT_RECURSIVE 0x8000 /* Apply to the entire subtree */

    -/*
    - * Arguments for how openat2(2) should open the target path. If only @flags and
    - * @mode are non-zero, then openat2(2) operates very similarly to openat(2).
    - *
    - * However, unlike openat(2), unknown or invalid bits in @flags result in
    - * -EINVAL rather than being silently ignored. @mode must be zero unless one of
    - * {O_CREAT, O_TMPFILE} are set.
    - *
    - * @flags: O_* flags.
    - * @mode: O_CREAT/O_TMPFILE file mode.
    - * @resolve: RESOLVE_* flags.
    - */
    -struct open_how {
    - __u64 flags;
    - __u64 mode;
    - __u64 resolve;
    -};
    -
    -#define OPEN_HOW_SIZE_VER0 24 /* sizeof first published struct */
    -#define OPEN_HOW_SIZE_LATEST OPEN_HOW_SIZE_VER0
    -
    -/* how->resolve flags for openat2(2). */
    -#define RESOLVE_NO_XDEV 0x01 /* Block mount-point crossings
    - (includes bind-mounts). */
    -#define RESOLVE_NO_MAGICLINKS 0x02 /* Block traversal through procfs-style
    - "magic-links". */
    -#define RESOLVE_NO_SYMLINKS 0x04 /* Block traversal through all symlinks
    - (implies OEXT_NO_MAGICLINKS) */
    -#define RESOLVE_BENEATH 0x08 /* Block "lexical" trickery like
    - "..", symlinks, and absolute
    - paths which escape the dirfd. */
    -#define RESOLVE_IN_ROOT 0x10 /* Make all jumps to "/" and ".."
    - be scoped inside the dirfd
    - (similar to chroot(2)). */
    -
    #endif /* _UAPI_LINUX_FCNTL_H */
    diff --git a/include/uapi/linux/openat2.h b/include/uapi/linux/openat2.h
    new file mode 100644
    index 000000000000..58b1eb711360
    --- /dev/null
    +++ b/include/uapi/linux/openat2.h
    @@ -0,0 +1,39 @@
    +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
    +#ifndef _UAPI_LINUX_OPENAT2_H
    +#define _UAPI_LINUX_OPENAT2_H
    +
    +#include <linux/types.h>
    +
    +/*
    + * Arguments for how openat2(2) should open the target path. If only @flags and
    + * @mode are non-zero, then openat2(2) operates very similarly to openat(2).
    + *
    + * However, unlike openat(2), unknown or invalid bits in @flags result in
    + * -EINVAL rather than being silently ignored. @mode must be zero unless one of
    + * {O_CREAT, O_TMPFILE} are set.
    + *
    + * @flags: O_* flags.
    + * @mode: O_CREAT/O_TMPFILE file mode.
    + * @resolve: RESOLVE_* flags.
    + */
    +struct open_how {
    + __u64 flags;
    + __u64 mode;
    + __u64 resolve;
    +};
    +
    +/* how->resolve flags for openat2(2). */
    +#define RESOLVE_NO_XDEV 0x01 /* Block mount-point crossings
    + (includes bind-mounts). */
    +#define RESOLVE_NO_MAGICLINKS 0x02 /* Block traversal through procfs-style
    + "magic-links". */
    +#define RESOLVE_NO_SYMLINKS 0x04 /* Block traversal through all symlinks
    + (implies OEXT_NO_MAGICLINKS) */
    +#define RESOLVE_BENEATH 0x08 /* Block "lexical" trickery like
    + "..", symlinks, and absolute
    + paths which escape the dirfd. */
    +#define RESOLVE_IN_ROOT 0x10 /* Make all jumps to "/" and ".."
    + be scoped inside the dirfd
    + (similar to chroot(2)). */
    +
    +#endif /* _UAPI_LINUX_OPENAT2_H */
    --
    2.24.0
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