libbinder: replace dup() with fcntl(F_DUPFD_CLOEXEC)
Replace calls to dup() with fcntl(F_DUPFD_CLOEXEC). The only difference
between the two is that O_CLOEXEC is set on the newly duped file
descriptor. This helps address file descriptor leaks crossing an exec()
boundary in multi-threaded processes, and potentially fixes the following
non-reproducible SELinux denials which may be occurring because of FD
leakage from netd to clatd/dnsmasq.
avc: denied { use } for comm="clatd" path="socket:[860297]" dev="sockfs"
ino=860297 scontext=u:r:clatd:s0 tcontext=u:r:untrusted_app:s0:c512,c768
tclass=fd permissive=0
avc: denied { read write } for comm="clatd" path="socket:[1414454]"
dev="sockfs" ino=1414454 scontext=u:r:clatd:s0
tcontext=u:r:system_server:s0 tclass=tcp_socket permissive=0
avc: denied { use } for comm="clatd" path="socket:[681600]" dev="sockfs"
ino=681600 scontext=u:r:clatd:s0 tcontext=u:r:priv_app:s0:c512,c768
tclass=fd permissive=0
Test: Device boots and no obvious problems
Change-Id: I9dcd9911a093f329c6f12e39d2c49ef3df651ae5
diff --git a/libs/binder/IShellCallback.cpp b/libs/binder/IShellCallback.cpp
index 8b97301..c793df3 100644
--- a/libs/binder/IShellCallback.cpp
+++ b/libs/binder/IShellCallback.cpp
@@ -16,6 +16,9 @@
#define LOG_TAG "ShellCallback"
+#include <unistd.h>
+#include <fcntl.h>
+
#include <binder/IShellCallback.h>
#include <utils/Log.h>
@@ -44,7 +47,7 @@
remote()->transact(OP_OPEN_OUTPUT_FILE, data, &reply, 0);
reply.readExceptionCode();
int fd = reply.readParcelFileDescriptor();
- return fd >= 0 ? dup(fd) : fd;
+ return fd >= 0 ? fcntl(fd, F_DUPFD_CLOEXEC, 0) : fd;
}
};