[PATCHv3 man-pages 3/3] open.2: describe O_BENEATH flag

[David Drysdale]

Signed-off-by: David Drysdale <drysdale@xxxxxxxxxx>
---
 man2/open.2 | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/man2/open.2 b/man2/open.2
index 956531b24b26..be40dd7710df 100644
--- a/man2/open.2
+++ b/man2/open.2
@@ -716,6 +716,31 @@ XFS support was added
 .\" commit ab29743117f9f4c22ac44c13c1647fb24fb2bafe
 in Linux 3.15.
 .TP
+.B O_BENEATH " (since Linux 3.??)"
+Ensure that the
+.I pathname
+is beneath the current working directory (for
+.BR open (2))
+or the
+.I dirfd
+(for
+.BR openat (2)).
+If the
+.I pathname
+is absolute or contains a path component of "..", the
+.BR open ()
+fails with the error
+.BR EPERM.
+This occurs even if ".." path component would not actually
+escape the original directory; for example, a
+.I pathname
+of "subdir/../filename" would be rejected.
+Path components that are symbolic links to absolute paths, or that are
+relative paths containing a ".." component, will also cause the
+.BR open ()
+operation to fail with the error
+.BR EPERM.
+.TP
 .B O_TRUNC
 If the file already exists and is a regular file and the access mode allows
 writing (i.e., is
@@ -984,6 +1009,13 @@ did not match the owner of the file and the caller was not privileged
 The operation was prevented by a file seal; see
 .BR fcntl (2).
 .TP
+.B EPERM
+The
+.B O_BENEATH
+flag was specified and the
+.I pathname
+was not beneath the relevant directory.
+.TP
 .B EROFS
 .I pathname
 refers to a file on a read-only filesystem and write access was
--
2.2.0.rc0.207.ga3a616c
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