Date: Mon, 10 May 2021 23:40:02 GMT From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 5e7cdf181792 - main - openat(2): add O_EMPTY_PATH Message-ID: <202105102340.14ANe2ro012136@gitrepo.freebsd.org>
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The branch main has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=5e7cdf1817924f8ae0333c0b53c2da32f35b65ea commit 5e7cdf1817924f8ae0333c0b53c2da32f35b65ea Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2021-05-06 17:16:53 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2021-05-10 23:39:24 +0000 openat(2): add O_EMPTY_PATH It reopens the passed file descriptor, checking the file backing vnode' current access rights against open mode. In particular, this flag allows to convert file descriptor opened with O_PATH, into operable file descriptor, assuming permissions allow that. Reviewed by: markj Tested by: Andrew Walker <awalker@ixsystems.com> Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D30148 --- lib/libc/sys/open.2 | 18 +++++++++++++++++- sys/kern/vfs_vnops.c | 2 ++ sys/sys/fcntl.h | 3 +++ 3 files changed, 22 insertions(+), 1 deletion(-) diff --git a/lib/libc/sys/open.2 b/lib/libc/sys/open.2 index a7806df69daf..5a6f161291f6 100644 --- a/lib/libc/sys/open.2 +++ b/lib/libc/sys/open.2 @@ -28,7 +28,7 @@ .\" @(#)open.2 8.2 (Berkeley) 11/16/93 .\" $FreeBSD$ .\" -.Dd March 18, 2021 +.Dd May 6, 2021 .Dt OPEN 2 .Os .Sh NAME @@ -169,6 +169,7 @@ O_CLOEXEC set FD_CLOEXEC upon open O_VERIFY verify the contents of the file O_RESOLVE_BENEATH path resolution must not cross the fd directory O_PATH record only the target path in the opened descriptor +O_EMPTY_PATH openat, open file referenced by fd if path is empty .Ed .Pp Opening a file with @@ -355,6 +356,21 @@ are not allowed. File opened with the .Dv O_PATH flag does not prevent non-forced unmount of the volume it belongs to. +.Pp +A file descriptor created with the +.Dv O_PATH +flag can be opened into normal (operable) file descriptor by +specifying it as the +.Fa fd +argument to +.Fn openat +with empty +.Fa path +and flag +.Dv O_EMPTY_PATH . +Such an open behaves as if the current path of the file referenced by +.Fa fd +is passed, except that the path walk permissions are not checked. See also the description of .Dv AT_EMPTY_PATH flag for diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c index d4396f67a67b..670bc4bf8fcc 100644 --- a/sys/kern/vfs_vnops.c +++ b/sys/kern/vfs_vnops.c @@ -200,6 +200,8 @@ open2nameif(int fmode, u_int vn_open_flags) res = ISOPEN | LOCKLEAF; if ((fmode & O_RESOLVE_BENEATH) != 0) res |= RBENEATH; + if ((fmode & O_EMPTY_PATH) != 0) + res |= EMPTYPATH; if ((vn_open_flags & VN_OPEN_NOAUDIT) == 0) res |= AUDITVNODE1; if ((vn_open_flags & VN_OPEN_NOCAPCHECK) != 0) diff --git a/sys/sys/fcntl.h b/sys/sys/fcntl.h index 58d46ae26338..8fa52aeacafd 100644 --- a/sys/sys/fcntl.h +++ b/sys/sys/fcntl.h @@ -141,6 +141,9 @@ typedef __pid_t pid_t; #endif #define O_DSYNC 0x01000000 /* POSIX data sync */ +#if __BSD_VISIBLE +#define O_EMPTY_PATH 0x02000000 +#endif /* * XXX missing O_RSYNC.
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