[PATCH] tools/libxs: Open /dev/xen/xenbus fds as O_CLOEXEC

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

The header description for xs_open() goes as far as to suggest that the fd is
O_CLOEXEC, but it isn't actually.

`xl devd` has been observed leaking /dev/xen/xenbus into children.

Link: https://github.com/QubesOS/qubes-issues/issues/8292
Reported-by: Demi Marie Obenour <demi@xxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Anthony PERARD <anthony@xxxxxxxxxxxxxx>
CC: Juergen Gross <jgross@xxxxxxxx>
CC: Demi Marie Obenour <demi@xxxxxxxxxxxxxxxxxxxxxx>
CC: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>

Entirely speculative patch based on a Matrix report
---
 tools/libs/store/xs.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/libs/store/xs.c b/tools/libs/store/xs.c
index 140b9a28395e..1f74fb3c44a2 100644
--- a/tools/libs/store/xs.c
+++ b/tools/libs/store/xs.c
@@ -54,6 +54,10 @@ struct xs_stored_msg {
 #include <dlfcn.h>
 #endif
 
+#ifndef O_CLOEXEC
+#define O_CLOEXEC 0
+#endif
+
 struct xs_handle {
        /* Communications channel to xenstore daemon. */
        int fd;
@@ -227,7 +231,7 @@ static int get_socket(const char *connect_to)
 static int get_dev(const char *connect_to)
 {
        /* We cannot open read-only because requests are writes */
-       return open(connect_to, O_RDWR);
+       return open(connect_to, O_RDWR|O_CLOEXEC);
 }
 
 static int all_restrict_cb(Xentoolcore__Active_Handle *ah, domid_t domid) {

base-commit: feb9158a620040846d76981acbe8ea9e2255a07b
-- 
2.30.2