On 2019-12-16, Florian Weimer <fweimer@xxxxxxxxxx> wrote:
diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h index 1d338357df8a..58c3a0e543c6 100644 --- a/include/uapi/linux/fcntl.h +++ b/include/uapi/linux/fcntl.h @@ -93,5 +93,40 @@ #define AT_RECURSIVE 0x8000 /* Apply to the entire subtree */ +/* + * 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. + * + * @flags: O_* flags. + * @mode: O_CREAT/O_TMPFILE file mode. + * @resolve: RESOLVE_* flags. + */ +struct open_how { + __aligned_u64 flags; + __u16 mode; + __u16 __padding[3]; /* must be zeroed */ + __aligned_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 */Would it be possible to move these to a new UAPI header? In glibc, we currently do not #include <linux/fcntl.h>. We need some of the AT_* constants in POSIX mode, and the header is not necessarily namespace-clean. If there was a separate header for openat2 support, we could use that easily, and we would only have to maintain the baseline definitions (which never change).
Sure, (assuming nobody objects) I can move it to "linux/openat2.h". -- Aleksa Sarai Senior Software Engineer (Containers) SUSE Linux GmbH <https://www.cyphar.com/>
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