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From: Ken Brown <kbrown@cornell.edu>
To: cygwin-patches@cygwin.com
Subject: [PATCH 4/7] Cygwin: fix fchown on sockets that are not socket files
Date: Thu, 25 Feb 2021 17:48:09 -0500	[thread overview]
Message-ID: <20210225224812.61523-5-kbrown@cornell.edu> (raw)
In-Reply-To: <20210225224812.61523-1-kbrown@cornell.edu>

If fchown(2) is called on an AF_LOCAL or AF_UNIX socket that is not a
socket file, the current code calls fhandler_disk_file::fchown in most
cases.  The latter expects to be operating on a disk file and uses the
socket's io_handle, which is not a file handle.

Fix this by calling fhandler_disk_file::fchown only if the
fhandler_socket object is a file (determined by testing dev().isfs()).
---
 winsup/cygwin/fhandler_socket_local.cc | 6 +++++-
 winsup/cygwin/fhandler_socket_unix.cc  | 8 +++++---
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/winsup/cygwin/fhandler_socket_local.cc b/winsup/cygwin/fhandler_socket_local.cc
index d1faa079a..349ade897 100644
--- a/winsup/cygwin/fhandler_socket_local.cc
+++ b/winsup/cygwin/fhandler_socket_local.cc
@@ -724,8 +724,12 @@ fhandler_socket_local::fchmod (mode_t newmode)
 int
 fhandler_socket_local::fchown (uid_t uid, gid_t gid)
 {
-  if (get_sun_path () && get_sun_path ()[0] == '\0')
+  if (!dev ().isfs ())
+    /* fchown called on a socket. */
     return fhandler_socket_wsock::fchown (uid, gid);
+
+  /* chown/lchown on a socket file.  [We won't get here if fchown is
+     called on a socket opened w/ O_PATH.] */
   fhandler_disk_file fh (pc);
   return fh.fchown (uid, gid);
 }
diff --git a/winsup/cygwin/fhandler_socket_unix.cc b/winsup/cygwin/fhandler_socket_unix.cc
index e08e9bdd9..573864b9f 100644
--- a/winsup/cygwin/fhandler_socket_unix.cc
+++ b/winsup/cygwin/fhandler_socket_unix.cc
@@ -2395,10 +2395,12 @@ fhandler_socket_unix::fchmod (mode_t newmode)
 int
 fhandler_socket_unix::fchown (uid_t uid, gid_t gid)
 {
-  if (sun_path ()
-      && (sun_path ()->un_len <= (socklen_t) sizeof (sa_family_t)
-	  || sun_path ()->un.sun_path[0] == '\0'))
+  if (!dev ().isfs ())
+    /* fchown called on a socket. */
     return fhandler_socket::fchown (uid, gid);
+
+  /* chown/lchown on a socket file.  [We won't get here if fchown is
+     called on a socket opened w/ O_PATH.] */
   fhandler_disk_file fh (pc);
   return fh.fchown (uid, gid);
 }
-- 
2.30.0


  parent reply	other threads:[~2021-02-25 22:48 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-25 22:48 [PATCH 0/7] Fix some system calls on sockets Ken Brown
2021-02-25 22:48 ` [PATCH 1/7] Cygwin: fix fstat on sockets that are not socket files Ken Brown
2021-02-25 22:48 ` [PATCH 2/7] Cygwin: fix fstatvfs " Ken Brown
2021-02-25 22:48 ` [PATCH 3/7] Cygwin: fix fchmod " Ken Brown
2021-02-25 22:48 ` Ken Brown [this message]
2021-02-25 22:48 ` [PATCH 5/7] Cygwin: fix facl " Ken Brown
2021-02-25 22:48 ` [PATCH 6/7] Cygwin: fix linkat(2) " Ken Brown
2021-02-25 22:48 ` [PATCH 7/7] Cygwin: simplify linkat with AT_EMPTY_PATH Ken Brown
2021-03-01 12:31 ` [PATCH 0/7] Fix some system calls on sockets Corinna Vinschen

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