avc_open() creates the netlink socket in nonblocking mode. If the
application later takes control of the netlink socket with
avc_netlink_acquire_fd() and then calls avc_netlink_loop(), it
will fail with EWOULDBLOCK.
To remedy this, remove the O_NONBLOCK flag from the netlink socket
at the start of avc_netlink_loop(). Also, with this fix, there is
no need for avc_open() to ever create a blocking socket, so change
that and update the man page.
Signed-off-by: Eamon Walsh <ewalsh@xxxxxxxxxxxxx>
---
man/man3/avc_netlink_loop.3 | 5 +----
src/avc.c | 2 +-
src/avc_internal.c | 2 ++
3 files changed, 4 insertions(+), 5 deletions(-)
diff --git a/libselinux/man/man3/avc_netlink_loop.3 b/libselinux/man/man3/avc_netlink_loop.3
index 67df6e4..7d8c9a4 100644
--- a/libselinux/man/man3/avc_netlink_loop.3
+++ b/libselinux/man/man3/avc_netlink_loop.3
@@ -43,10 +43,7 @@ to take ownership of it in application code. The
.I blocking
argument specifies whether read operations on the socket will block.
.BR avc_open (3)
-calls this function internally, specifying non-blocking behavior (unless
-threading callbacks were explicitly set using the deprecated
-.BR avc_init (3)
-interface, in which case blocking behavior is set).
+calls this function internally, specifying non-blocking behavior.
.B avc_netlink_close
closes the netlink socket. This function is called automatically by
diff --git a/libselinux/src/avc.c b/libselinux/src/avc.c
index 881b915..5c8def0 100644
--- a/libselinux/src/avc.c
+++ b/libselinux/src/avc.c
@@ -222,7 +222,7 @@ int avc_init(const char *prefix,
avc_enforcing = rc;
}
- rc = avc_netlink_open(avc_using_threads);
+ rc = avc_netlink_open(0);
if (rc < 0) {
avc_log(SELINUX_ERROR,
"%s: can't open netlink socket: %d (%s)\n",
diff --git a/libselinux/src/avc_internal.c b/libselinux/src/avc_internal.c
index 8372f52..90dfa51 100644
--- a/libselinux/src/avc_internal.c
+++ b/libselinux/src/avc_internal.c
@@ -233,6 +233,8 @@ void avc_netlink_loop(void)
int rc;
char buf[1024] __attribute__ ((aligned));
+ fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) & ~O_NONBLOCK);
+
while (1) {
errno = 0;
rc = avc_netlink_receive(buf, sizeof(buf));
--
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