On Tue, 2018-05-15 at 09:43 -0400, Stephen Smalley wrote:
> On 05/15/2018 09:36 AM, Stephen Smalley wrote:
> > On 05/15/2018 04:25 AM, Richard Haines via Selinux wrote:
> > > Add binder tests. See tests/binder/test_binder.c for details on
> > > message flows to test security_binder*() functions.
> > >
> > > Signed-off-by: Richard Haines <richard_c_haines@xxxxxxxxxxxxxx>
> > > ---
> > > README.md | 8 +
> > > defconfig | 8 +
> > > policy/Makefile | 2 +-
> > > policy/test_binder.te | 83 +++++++
> > > tests/Makefile | 2 +-
> > > tests/binder/Makefile | 7 +
> > > tests/binder/check_binder.c | 80 +++++++
> > > tests/binder/test | 131 +++++++++++
> > > tests/binder/test_binder.c | 543
> > > ++++++++++++++++++++++++++++++++++++++++++++
> > > 9 files changed, 862 insertions(+), 2 deletions(-)
> > > create mode 100644 policy/test_binder.te
> > > create mode 100644 tests/binder/Makefile
> > > create mode 100644 tests/binder/check_binder.c
> > > create mode 100644 tests/binder/test
> > > create mode 100644 tests/binder/test_binder.c
> > >
> > > diff --git a/README.md b/README.md
> > > index c9f3b2b..60a249e 100644
> > > --- a/README.md
> > > +++ b/README.md
> > > @@ -141,6 +141,14 @@ directory or you can follow these broken-out
> > > steps:
> > > The broken-out steps allow you to run the tests multiple times
> > > without
> > > loading policy each time.
> > >
> > > +Note that if leaving the test policy in-place for further
> > > testing, the
> > > +policy build process changes a boolean:
> > > + On policy load: setsebool allow_domain_fd_use=0
> > > + On policy unload: setsebool allow_domain_fd_use=1
> > > +The consequence of this is that after a system reboot, the
> > > boolean
> > > +defaults to true. Therefore if running the fdreceive or binder
> > > tests,
> > > +reset the boolean to false, otherwise some tests will fail.
> >
> > This isn't accurate - we aren't doing setsebool -P so the boolean
> > change is not persistent across
> > reboots. It will persist across policy reloads however because the
> > kernel preserves booleans across
> > policy reloads.
>
> Sorry, never mind - I misread the text above. You are correct.
>
> >
> > > +
> > > 4) Review the test results.
> > >
> > > As each test script is run, the name of the script will be
> > > displayed followed
> > > diff --git a/defconfig b/defconfig
> > > index 7dce8bc..dc6ef30 100644
> > > --- a/defconfig
> > > +++ b/defconfig
> > > @@ -51,3 +51,11 @@ CONFIG_CRYPTO_USER=m
> > > # This is enabled to test overlayfs SELinux integration.
> > > # It is not required for SELinux operation itself.
> > > CONFIG_OVERLAY_FS=m
> > > +
> > > +# Android binder implementations.
> > > +# These are enabled to test the binder controls in
> > > +# tests/binder; they are not required for SELinux operation
> > > itself.
> > > +CONFIG_ANDROID=y
> > > +CONFIG_ANDROID_BINDER_IPC=y
> > > +CONFIG_ANDROID_BINDER_DEVICES="binder"
> > > +# CONFIG_ANDROID_BINDER_IPC_SELFTEST is not set
> >
> > I don't think we need the last line.
It appears it is requred as if not there are complaints when building,
in fact I missed some out and should be:
# Android binder implementations.
# These are enabled to test the binder controls in
# tests/binder; they are not required for SELinux operation itself.
# The 'is not set' items MUST be included unless they are required by
your configuration.
# CONFIG_ASHMEM is not set
# CONFIG_ION is not set
CONFIG_ANDROID_BINDER_DEVICES="binder"
CONFIG_ANDROID_BINDER_IPC=y
# CONFIG_ANDROID_BINDER_IPC_SELFTEST is not set
> >
> > > diff --git a/policy/Makefile b/policy/Makefile
> > > index 8ed5e46..5a9d411 100644
> > > --- a/policy/Makefile
> > > +++ b/policy/Makefile
> > > @@ -25,7 +25,7 @@ TARGETS = \
> > > test_task_getsid.te test_task_setpgid.te
> > > test_task_setsched.te \
> > > test_transition.te test_inet_socket.te
> > > test_unix_socket.te \
> > > test_mmap.te test_overlayfs.te test_mqueue.te
> > > test_mac_admin.te \
> > > - test_ibpkey.te test_atsecure.te
> > > + test_ibpkey.te test_atsecure.te test_binder.te
> >
> > Likely need to make this conditional on the binder class being
> > defined in the policy;
> > see similar logic for e.g. cap_userns, icmp_socket, etc. Otherwise
> > policy won't build
> > on earlier Fedora/RHEL before definition of the binder class.
> >
I'll fix
> > >
> > > ifeq ($(shell [ $(POL_VERS) -ge 24 ] && echo true),true)
> > > TARGETS += test_bounds.te
> > > diff --git a/policy/test_binder.te b/policy/test_binder.te
> > > new file mode 100644
> > > index 0000000..c4ad2ae
> > > --- /dev/null
> > > +++ b/policy/test_binder.te
> > > @@ -0,0 +1,83 @@
> > > +
> > > +attribute binderdomain;
> > > +
> > > +#
> > > +################################## Manager
> > > ###################################
> > > +#
> > > +type test_binder_mgr_t;
> > > +domain_type(test_binder_mgr_t)
> > > +unconfined_runs_test(test_binder_mgr_t)
> > > +typeattribute test_binder_mgr_t testdomain;
> > > +typeattribute test_binder_mgr_t binderdomain;
> > > +allow test_binder_mgr_t self:binder { set_context_mgr call };
> > > +allow test_binder_mgr_t device_t:chr_file { ioctl open read
> > > write map };
> >
> > Wondering if we should define a .fc file with /dev/binder and a
> > proper binder_device_t type
> > and restorecon it before the test. But not clear it is worth
> > it. Never mind.
> >
> > > +allow test_binder_mgr_t self:capability { sys_nice };
> >
> > Needed or just to suppress noise in the audit?
The binder driver does something with nice, but tests work okay
without.
> >
> > > +allow test_binder_client_t test_binder_mgr_t:fd use;
> > > +
> > > +#
> > > +################################# Client
> > > ####################################
> > > +#
> > > +type test_binder_client_t;
> > > +domain_type(test_binder_client_t)
> > > +unconfined_runs_test(test_binder_client_t)
> > > +typeattribute test_binder_client_t testdomain;
> > > +typeattribute test_binder_client_t binderdomain;
> > > +allow test_binder_client_t self:binder { call };
> > > +allow test_binder_client_t test_binder_mgr_t:binder { call
> > > transfer impersonate };
> >
> > Are you actually exercising impersonate? I largely didn't expect
> > it to ever be used in Android itself,
> > just included the check because I saw that it was technically
> > possible as far as the kernel interface
> > is concerned.
I think I am. The client requests the Managers fd, then uses it to send
message. I patched kernel to check this. Also I read your helpful note:
https://marc.info/?l=seandroid-list&m=141901419332280&w=2
> >
> > > +allow test_binder_client_t device_t:chr_file { ioctl open read
> > > write map };
> > > +# For fstat:
> > > +allow test_binder_client_t device_t:chr_file getattr;
> > > +
> > > +#
> > > +############################## Client no call
> > > ################################
> > > +#
> > > +type test_binder_client_no_call_t;
> > > +domain_type(test_binder_client_no_call_t)
> > > +unconfined_runs_test(test_binder_client_no_call_t)
> > > +typeattribute test_binder_client_no_call_t testdomain;
> > > +typeattribute test_binder_client_no_call_t binderdomain;
> > > +allow test_binder_client_no_call_t device_t:chr_file { ioctl
> > > open read write map };
> > > +
> > > +#
> > > +############################ Client no transfer
> > > #############################
> > > +#
> > > +type test_binder_client_no_transfer_t;
> > > +domain_type(test_binder_client_no_transfer_t)
> > > +unconfined_runs_test(test_binder_client_no_transfer_t)
> > > +typeattribute test_binder_client_no_transfer_t testdomain;
> > > +typeattribute test_binder_client_no_transfer_t binderdomain;
> > > +allow test_binder_client_no_transfer_t test_binder_mgr_t:binder
> > > { call };
> > > +allow test_binder_client_no_transfer_t device_t:chr_file { ioctl
> > > open read write map };
> > > +
> > > +#
> > > +########################## Manager no fd {use}
> > > ###############################
> > > +#
> > > +type test_binder_mgr_no_fd_t;
> > > +domain_type(test_binder_mgr_no_fd_t)
> > > +unconfined_runs_test(test_binder_mgr_no_fd_t)
> > > +typeattribute test_binder_mgr_no_fd_t testdomain;
> > > +typeattribute test_binder_mgr_no_fd_t binderdomain;
> > > +allow test_binder_mgr_no_fd_t self:binder { set_context_mgr call
> > > };
> > > +allow test_binder_mgr_no_fd_t device_t:chr_file { ioctl open
> > > read write map };
> > > +allow test_binder_mgr_no_fd_t self:capability { sys_nice };
> > > +allow test_binder_client_t test_binder_mgr_no_fd_t:binder { call
> > > transfer };
> > > +
> > > +#
> > > +########################### Client no impersonate
> > > ############################
> > > +#
> > > +type test_binder_client_no_im_t;
> > > +domain_type(test_binder_client_no_im_t)
> > > +unconfined_runs_test(test_binder_client_no_im_t)
> > > +typeattribute test_binder_client_no_im_t testdomain;
> > > +typeattribute test_binder_client_no_im_t binderdomain;
> > > +allow test_binder_client_no_im_t self:binder { call };
> > > +allow test_binder_client_no_im_t test_binder_mgr_t:binder { call
> > > transfer };
> > > +allow test_binder_client_no_im_t device_t:chr_file { ioctl open
> > > read write map };
> > > +allow test_binder_client_no_im_t test_binder_mgr_t:fd use;
> > > +allow test_binder_client_no_im_t device_t:chr_file getattr;
> > > +
> > > +#
> > > +############ Allow these domains to be entered from sysadm
> > > domain ############
> > > +#
> > > +miscfiles_domain_entry_test_files(binderdomain)
> > > +userdom_sysadm_entry_spec_domtrans_to(binderdomain)
> > > diff --git a/tests/Makefile b/tests/Makefile
> > > index 27ed6eb..7607c22 100644
> > > --- a/tests/Makefile
> > > +++ b/tests/Makefile
> > > @@ -10,7 +10,7 @@ SUBDIRS:= domain_trans entrypoint execshare
> > > exectrace execute_no_trans \
> > > task_setnice task_setscheduler task_getscheduler
> > > task_getsid \
> > > task_getpgid task_setpgid file ioctl capable_file
> > > capable_net \
> > > capable_sys dyntrans dyntrace bounds nnp_nosuid mmap
> > > unix_socket \
> > > - inet_socket overlay checkreqprot mqueue mac_admin
> > > atsecure
> > > + inet_socket overlay checkreqprot mqueue mac_admin
> > > atsecure binder
> >
> > Likely needs to be conditional on binder class being defined in
> > policy as with cap_userns,
> > and also depends on e.g. linux/android/binder.h
> > existing? Otherwise will break build on earlier
> > Fedora/RHEL releases.
> >
I'll fix
> > >
> > > ifeq ($(shell grep -q cap_userns
> > > $(POLDEV)/include/support/all_perms.spt && echo true),true)
> > > ifneq ($(shell ./kvercmp $$(uname -r) 4.7),-1)
> > > diff --git a/tests/binder/Makefile b/tests/binder/Makefile
> > > new file mode 100644
> > > index 0000000..a60eeb3
> > > --- /dev/null
> > > +++ b/tests/binder/Makefile
> > > @@ -0,0 +1,7 @@
> > > +TARGETS = check_binder test_binder
> > > +
> > > +LDLIBS += -lselinux
> > > +
> > > +all: $(TARGETS)
> > > +clean:
> > > + rm -f $(TARGETS)
> > > diff --git a/tests/binder/check_binder.c
> > > b/tests/binder/check_binder.c
> > > new file mode 100644
> > > index 0000000..3d553a0
> > > --- /dev/null
> > > +++ b/tests/binder/check_binder.c
> > > @@ -0,0 +1,80 @@
> > > +#include <stdio.h>
> > > +#include <stdlib.h>
> > > +#include <string.h>
> > > +#include <unistd.h>
> > > +#include <fcntl.h>
> > > +#include <errno.h>
> > > +#include <stdbool.h>
> > > +#include <sys/mman.h>
> > > +#include <sys/ioctl.h>
> > > +#include <linux/android/binder.h>
> > > +
> > > +static void usage(char *progname)
> > > +{
> > > + fprintf(stderr,
> > > + "usage: %s [-v]\n"
> > > + "Where:\n\t"
> > > + "-v Print binder version.\n", progname);
> > > + exit(-1);
> > > +}
> > > +
> > > +int main(int argc, char **argv)
> > > +{
> > > + int opt, result, fd;
> > > + char *driver = "/dev/binder";
> > > + bool verbose;
> > > + void *mapped;
> > > + size_t mapsize = 1024;
> > > + struct binder_version vers;
> > > +
> > > + while ((opt = getopt(argc, argv, "v")) != -1) {
> > > + switch (opt) {
> > > + case 'v':
> > > + verbose = true;
> > > + break;
> > > + default:
> > > + usage(argv[0]);
> > > + }
> > > + }
> > > +
> > > + fd = open(driver, O_RDWR | O_CLOEXEC);
> > > + if (fd < 0) {
> > > + fprintf(stderr, "Cannot open: %s error: %s\n",
> > > + driver, strerror(errno));
> > > + exit(-1);
> > > + }
> > > +
> > > + /* Need this or no VMA error from kernel */
> > > + mapped = mmap(NULL, mapsize, PROT_READ, MAP_PRIVATE, fd,
> > > 0);
> > > + if (mapped == MAP_FAILED) {
> > > + fprintf(stderr, "mmap error: %s\n",
> > > strerror(errno));
> > > + close(fd);
> > > + exit(-1);
> > > + }
> > > +
> > > + result = ioctl(fd, BINDER_VERSION, &vers);
> > > + if (result < 0) {
> > > + fprintf(stderr, "ioctl BINDER_VERSION: %s\n",
> > > + strerror(errno));
> > > + goto brexit;
> > > + }
> > > +
> > > + if (vers.protocol_version !=
> > > BINDER_CURRENT_PROTOCOL_VERSION) {
> > > + fprintf(stderr,
> > > + "Binder kernel version: %d differs from
> > > user space version: %d\n",
> > > + vers.protocol_version,
> > > + BINDER_CURRENT_PROTOCOL_VERSION);
> > > + result = -1;
> > > + goto brexit;
> > > + }
> > > +
> > > + if (verbose)
> > > + fprintf(stderr, "Binder kernel version: %d\n",
> > > + vers.protocol_version);
> > > +
> > > +brexit:
> > > + munmap(mapped, mapsize);
> > > + close(fd);
> > > +
> > > + return result;
> > > +}
> > > diff --git a/tests/binder/test b/tests/binder/test
> > > new file mode 100644
> > > index 0000000..434ae32
> > > --- /dev/null
> > > +++ b/tests/binder/test
> > > @@ -0,0 +1,131 @@
> > > +#!/usr/bin/perl
> > > +use Test::More;
> > > +
> > > +BEGIN {
> > > + $basedir = $0;
> > > + $basedir =~ s|(.*)/[^/]*|$1|;
> > > +
> > > + # allow binder info to be shown
> > > + $v = $ARGV[0];
> > > + if ($v) {
> > > + if ( $v ne "-v" ) {
> > > + plan skip_all => "Invalid option (use -v)";
> > > + }
> > > + }
> > > +
> > > + # check if binder driver available and the kernel/userspace
> > > versions.
> > > + if ( system("$basedir/check_binder 2> /dev/null") != 0 ) {
> > > + plan skip_all =>
> > > + "Binder not supported or kernel/userspace versions
> > > differ";
> > > + }
> > > + else {
> > > + plan tests => 6;
> > > + }
> > > +}
> > > +
> > > +if ($v) {
> >
> > Duplicating the test cases for $v and !$v seems prone to
> > inconsistency in the future;
> > can't we just embed $v into the command string being executed?
I'll find another way as I tried that but perl complained about
uninitialised variables (or something like that)
> >
> > > + if ( ( $pid = fork() ) == 0 ) {
> > > + exec "runcon -t test_binder_mgr_t $basedir/test_binder
> > > -v manager";
> > > + }
> > > +
> > > + select( undef, undef, undef, 0.25 ); # Give it a moment
> > > to initialize.
> > > +
> > > + # Verify that authorized client can transact with the
> > > manager.
> > > + $result =
> > > + system "runcon -t test_binder_client_t
> > > $basedir/test_binder -v client";
> > > + ok( $result eq 0 );
> >
> > This test is failing for me (with or without -v):
> > # ./test -v
> > 1..6
> > Manager PID: 5608 Process context:
> > unconfined_u:unconfined_r:test_binder_mgr_t:s0-s0:c0.c1023
> > Client PID: 5609 Process context:
> > unconfined_u:unconfined_r:test_binder_client_t:s0-s0:c0.c1023
> > Client read_consumed: 28
> > Manager read_consumed: 72
> > Client command: BR_NOOP
> > Manager command: BR_NOOP
> > Client command: BR_INCREFS
> > Manager command: BR_TRANSACTION
> > Client command: BR_TRANSACTION_COMPLETE
> > BR_TRANSACTION data:
> > handle: 0
> > cookie: 0
> > code: 0
> > flag: TF_ACCEPT_FDS
> > sender pid: 5609
> > sender euid: 0
> > data_size: 24
> > offsets_size: 8
> > Sending BC_REPLY
> > Manager read_consumed: 8
> > Manager command: BR_NOOP
> > Manager command: BR_TRANSACTION_COMPLETE
> > Client read_consumed: 72
> > Client command: BR_NOOP
> > Client command: BR_REPLY
> > BR_REPLY data:
> > handle: 0
> > cookie: 0
> > code: 0
> > flag: TF_ACCEPT_FDS
> > sender pid: 0
> > sender euid: 0
> > data_size: 24
> > offsets_size: 8
> > Retrieved Managers fd: 4 st_dev: 6
> > Client read_consumed: 8
> > Client using Managers FD command: BR_NOOP
> > Client using Managers FD command: BR_FAILED_REPLY
> > Client using Managers received FD failed response
> > Manager read_consumed: 4
> > Manager command: BR_NOOP
> > not ok 1
> > # Failed test at ./test line 36.
>
> Just realized that I was testing with a kernel that still had Casey's
> stacking support enabled.
> Will re-try without that.
I'm rebuilding on Fedora 28 so I'll test that as well.
>
> >
> >
> > > +
> > > + # Verify that client cannot call manager (no call perm).
> > > + $result = system
> > > +"runcon -t test_binder_client_no_call_t $basedir/test_binder -v
> > > client 2>&1";
> > > + ok( $result >> 8 eq 9 );
> > > +
> > > + # Verify that client cannot communicate with manager (no
> > > impersonate perm).
> > > + $result = system
> > > +"runcon -t test_binder_client_no_im_t $basedir/test_binder -v
> > > client 2>&1";
> > > + ok( $result >> 8 eq 102 );
> > > +
> > > + # Verify that client cannot communicate with manager (no
> > > transfer perm).
> > > + $result = system
> > > +"runcon -t test_binder_client_no_transfer_t $basedir/test_binder
> > > -v client 2>&1";
> > > + ok( $result >> 8 eq 9 );
> > > +
> > > + # Kill the manager.
> > > + kill TERM, $pid;
> > > +
> > > + # Verify that client cannot become a manager (no
> > > set_context_mgr perm).
> > > + $result =
> > > + system
> > > + "runcon -t test_binder_client_t $basedir/test_binder -v
> > > manager 2>&1";
> > > + ok( $result >> 8 eq 4 );
> > > +
> > > +# Start manager to test that selinux_binder_transfer_file()
> > > fails when fd { use } is denied by policy.
> > > + if ( ( $pid = fork() ) == 0 ) {
> > > + exec
> > > + "runcon -t test_binder_mgr_no_fd_t
> > > $basedir/test_binder -v manager";
> > > + }
> > > +
> > > + select( undef, undef, undef, 0.25 ); # Give it a moment
> > > to initialize.
> > > +
> > > +# Verify that authorized client can communicate with the server,
> > > however the fd passed will not be valid for manager
> > > +# domain and binder will return BR_FAILED_REPLY.
> > > + $result =
> > > + system
> > > + "runcon -t test_binder_client_t $basedir/test_binder -v
> > > client 2>&1";
> > > + ok( $result >> 8 eq 9 );
> > > +
> > > + # Kill the manager
> > > + kill TERM, $pid;
> > > +}
> > > +else {
> > > + if ( ( $pid = fork() ) == 0 ) {
> > > + exec "runcon -t test_binder_mgr_t $basedir/test_binder
> > > manager";
> > > + }
> > > +
> > > + select( undef, undef, undef, 0.25 ); # Give it a moment
> > > to initialize.
> > > +
> > > + # Verify that authorized client can transact with the
> > > manager.
> > > + $result =
> > > + system "runcon -t test_binder_client_t
> > > $basedir/test_binder client";
> > > + ok( $result eq 0 );
> > > +
> > > + # Verify that client cannot call manager (no call perm).
> > > + $result = system
> > > + "runcon -t test_binder_client_no_call_t
> > > $basedir/test_binder client 2>&1";
> > > + ok( $result >> 8 eq 9 );
> > > +
> > > + # Verify that client cannot communicate with manager (no
> > > impersonate perm).
> > > + $result = system
> > > + "runcon -t test_binder_client_no_im_t $basedir/test_binder
> > > client 2>&1";
> > > + ok( $result >> 8 eq 102 );
> > > +
> > > + # Verify that client cannot communicate with manager (no
> > > transfer perm).
> > > + $result = system
> > > +"runcon -t test_binder_client_no_transfer_t $basedir/test_binder
> > > client 2>&1";
> > > + ok( $result >> 8 eq 9 );
> > > +
> > > + # Kill the manager.
> > > + kill TERM, $pid;
> > > +
> > > + # Verify that client cannot become a manager (no
> > > set_context_mgr perm).
> > > + $result =
> > > + system "runcon -t test_binder_client_t
> > > $basedir/test_binder manager 2>&1";
> > > + ok( $result >> 8 eq 4 );
> > > +
> > > +# Start manager to test that selinux_binder_transfer_file()
> > > fails when fd { use } is denied by policy.
> > > + if ( ( $pid = fork() ) == 0 ) {
> > > + exec "runcon -t test_binder_mgr_no_fd_t
> > > $basedir/test_binder manager";
> > > + }
> > > +
> > > + select( undef, undef, undef, 0.25 ); # Give it a moment
> > > to initialize.
> > > +
> > > +# Verify that authorized client can communicate with the server,
> > > however the fd passed will not be valid for manager
> > > +# domain and binder will return BR_FAILED_REPLY.
> > > + $result =
> > > + system "runcon -t test_binder_client_t
> > > $basedir/test_binder client 2>&1";
> > > + ok( $result >> 8 eq 9 );
> > > +
> > > + # Kill the manager
> > > + kill TERM, $pid;
> > > +}
> > > +exit;
> > > diff --git a/tests/binder/test_binder.c
> > > b/tests/binder/test_binder.c
> > > new file mode 100644
> > > index 0000000..8881cce
> > > --- /dev/null
> > > +++ b/tests/binder/test_binder.c
> > > @@ -0,0 +1,543 @@
> > > +/*
> > > + * This is a simple binder client/server(manager) that only uses
> > > the
> > > + * raw ioctl commands. It does not rely on a 'service manager'
> > > as in
> > > + * the Android world as it only uses one 'target' = 0.
> > > + *
> > > + * The transaction/reply flow is basically:
> > > + * Client Manager
> > > + * ======== =========
> > > + *
> > > + * Becomes context
> > > manager
> > > + * Send transaction
> > > + * requesting file
> > > + * descriptor from
> > > + * the Manager
> > > + * --------------------------------------->
> > > + * Manager replies with
> > > its
> > > + * binder file descriptor
> > > + * <--------------------------------------
> > > + * Check fd valid, if so send
> > > + * TF_ONE_WAY transaction to Manager
> > > + * using the received fd
> > > + * --------------------------------------->
> > > + * End of tests so
> > > Manager
> > > + * waits to be killed
> > > + * Client exits
> > > + *
> > > + * Using binder test policy the following will be validated:
> > > + * security_binder_set_context_mgr() binder { set_context_mgr
> > > }
> > > + * security_binder_transaction() binder { call
> > > impersonate }
> > > + * security_binder_transfer_binder() binder { transfer }
> > > + * security_binder_transfer_file() fd { use }
> > > + *
> > > + * TODO security_binder_transfer_file() uses BPF if configured
> > > in kernel.
> > > + */
> > > +
> > > +#include <errno.h>
> > > +#include <fcntl.h>
> > > +#include <inttypes.h>
> > > +#include <stdio.h>
> > > +#include <stdlib.h>
> > > +#include <string.h>
> > > +#include <unistd.h>
> > > +#include <sys/stat.h>
> > > +#include <stdbool.h>
> > > +#include <sys/mman.h>
> > > +#include <sys/ioctl.h>
> > > +#include <selinux/selinux.h>
> > > +#include <linux/android/binder.h>
> > > +
> > > +static uint32_t target; /* This will be set to '0' as only need
> > > one target */
> > > +static bool verbose;
> > > +
> > > +static int binder_parse(int fd, uintptr_t ptr, size_t size, char
> > > *text);
> > > +
> > > +static void usage(char *progname)
> > > +{
> > > + fprintf(stderr,
> > > + "usage: %s [-v] manager | client\n"
> > > + "Where:\n\t"
> > > + "-v Print context and command
> > > information.\n\t"
> > > + "manager Act as binder context manager.\n\t"
> > > + "client Act as binder client.\n"
> > > + "\nNote: Ensure this boolean command is run when
> > > "
> > > + "testing after a reboot:\n\t"
> > > + "setsebool allow_domain_fd_use=0\n", progname);
> > > + exit(1);
> > > +}
> > > +
> > > +static const char *cmd_name(uint32_t cmd)
> > > +{
> > > + switch (cmd) {
> > > + case BR_NOOP:
> > > + return "BR_NOOP";
> > > + case BR_TRANSACTION_COMPLETE:
> > > + return "BR_TRANSACTION_COMPLETE";
> > > + case BR_INCREFS:
> > > + return "BR_INCREFS";
> > > + case BR_ACQUIRE:
> > > + return "BR_ACQUIRE";
> > > + case BR_RELEASE:
> > > + return "BR_RELEASE";
> > > + case BR_DECREFS:
> > > + return "BR_DECREFS";
> > > + case BR_TRANSACTION:
> > > + return "BR_TRANSACTION";
> > > + case BR_REPLY:
> > > + return "BR_REPLY";
> > > + case BR_FAILED_REPLY:
> > > + return "BR_FAILED_REPLY";
> > > + case BR_DEAD_REPLY:
> > > + return "BR_DEAD_REPLY";
> > > + case BR_DEAD_BINDER:
> > > + return "BR_DEAD_BINDER";
> > > + case BR_ERROR:
> > > + return "BR_ERROR";
> > > + /* fallthrough */
> > > + default:
> > > + return "Unknown command";
> > > + }
> > > +}
> > > +
> > > +void print_trans_data(struct binder_transaction_data *txn)
> > > +{
> > > + printf("\thandle: %ld\n", (unsigned long)txn-
> > > >target.handle);
> > > + printf("\tcookie: %lld\n", txn->cookie);
> > > + printf("\tcode: %u\n", txn->code);
> > > + switch (txn->flags) {
> > > + case TF_ONE_WAY:
> > > + printf("\tflag: TF_ONE_WAY\n");
> > > + break;
> > > + case TF_ROOT_OBJECT:
> > > + printf("\tflag: TF_ROOT_OBJECT\n");
> > > + break;
> > > + case TF_STATUS_CODE:
> > > + printf("\tflag: TF_STATUS_CODE\n");
> > > + break;
> > > + case TF_ACCEPT_FDS:
> > > + printf("\tflag: TF_ACCEPT_FDS\n");
> > > + break;
> > > + default:
> > > + printf("Unknown flag: %u\n", txn->flags);
> > > + }
> > > + printf("\tsender pid: %u\n", txn->sender_pid);
> > > + printf("\tsender euid: %u\n", txn->sender_euid);
> > > + printf("\tdata_size: %llu\n", txn->data_size);
> > > + printf("\toffsets_size: %llu\n", txn->offsets_size);
> > > +}
> > > +
> > > +
> > > +static int send_reply(int fd, struct binder_transaction_data
> > > *txn_in)
> > > +{
> > > + int result;
> > > + unsigned int writebuf[1024];
> > > + struct flat_binder_object obj;
> > > + struct binder_write_read bwr;
> > > + struct binder_transaction_data *txn;
> > > +
> > > + if (txn_in->flags == TF_ONE_WAY) {
> > > + if (verbose)
> > > + printf("No reply to BC_TRANSACTION as
> > > flags = TF_ONE_WAY\n");
> > > + return 0;
> > > + }
> > > +
> > > + if (verbose)
> > > + printf("Sending BC_REPLY\n");
> > > +
> > > + writebuf[0] = BC_REPLY;
> > > + txn = (struct binder_transaction_data *)(&writebuf[1]);
> > > +
> > > + memset(txn, 0, sizeof(*txn));
> > > + txn->target.handle = txn_in->target.handle;
> > > + txn->cookie = txn_in->cookie;
> > > + txn->code = txn_in->code;
> > > + txn->flags = TF_ACCEPT_FDS;
> > > +
> > > + memset(&obj, 0, sizeof(struct flat_binder_object));
> > > + obj.hdr.type = BINDER_TYPE_FD;
> > > + obj.flags = 0x7f | FLAT_BINDER_FLAG_ACCEPTS_FDS;
> > > + obj.binder = txn->target.handle;
> > > + obj.cookie = txn->cookie;
> > > + /* The binder fd is used for testing as it allows policy
> > > to set
> > > + * whether the Client/Manager can be allowed access (fd
> > > use) or
> > > + * not. For example test_binder_mgr_t has:
> > > + * allow test_binder_client_t
> > > test_binder_mgr_t:fd use;
> > > + * whereas test_binder_mgr_no_fd_t does not allow this
> > > fd use.
> > > + *
> > > + * This also allows a check for the impersonate
> > > permission later as
> > > + * the Client will use this (the Managers fd) to send a
> > > transaction.
> > > + */
> > > + obj.handle = fd;
> > > +
> > > + txn->data_size = sizeof(struct flat_binder_object);
> > > + txn->data.ptr.buffer = (uintptr_t)&obj;
> > > + txn->data.ptr.offsets = (uintptr_t)&obj +
> > > + sizeof(struct
> > > flat_binder_object);
> > > + txn->offsets_size = sizeof(binder_size_t);
> > > +
> > > + memset(&bwr, 0, sizeof(bwr));
> > > + bwr.write_buffer = (unsigned long)writebuf;
> > > + bwr.write_size = sizeof(writebuf[0]) + sizeof(*txn);
> > > +
> > > + result = ioctl(fd, BINDER_WRITE_READ, &bwr);
> > > + if (result < 0) {
> > > + fprintf(stderr, "%s ioctl BINDER_WRITE_READ:
> > > %s\n",
> > > + __func__, strerror(errno));
> > > + return -1;
> > > + }
> > > +
> > > + return result;
> > > +}
> > > +
> > > +/* This retrieves the requested Managers file descriptor, then
> > > using this
> > > + * sends a simple transaction to trigger the impersonate
> > > permission.
> > > + */
> > > +static void extract_fd_and_respond(struct
> > > binder_transaction_data *txn_in)
> > > +{
> > > + int result;
> > > + uint32_t cmd;
> > > + struct stat sb;
> > > + struct binder_write_read bwr;
> > > + struct flat_binder_object *obj;
> > > + struct binder_transaction_data *txn;
> > > + unsigned int readbuf[32];
> > > + unsigned int writebuf[1024];
> > > + binder_size_t *offs = (binder_size_t
> > > *)(uintptr_t)txn_in->data.ptr.offsets;
> > > +
> > > + /* Get the fbo that contains the Managers binder file
> > > descriptor. */
> > > + obj = (struct flat_binder_object *)
> > > + (((char *)(uintptr_t)txn_in->data.ptr.buffer) +
> > > *offs);
> > > +
> > > + /* fstat this just to see if a valid fd */
> > > + result = fstat(obj->handle, &sb);
> > > + if (result < 0) {
> > > + fprintf(stderr, "Not a valid fd: %s\n",
> > > strerror(errno));
> > > + exit(100);
> > > + }
> > > +
> > > + if (verbose)
> > > + printf("Retrieved Managers fd: %d st_dev:
> > > %ld\n",
> > > + obj->handle, sb.st_dev);
> > > +
> > > + /* Send response using Managers fd to trigger
> > > impersonate check. */
> > > + writebuf[0] = BC_TRANSACTION;
> > > + txn = (struct binder_transaction_data *)(&writebuf[1]);
> > > + memset(txn, 0, sizeof(*txn));
> > > + txn->target.handle = target;
> > > + txn->cookie = 0;
> > > + txn->code = 0;
> > > + txn->flags = TF_ONE_WAY;
> > > +
> > > + txn->data_size = 0;
> > > + txn->data.ptr.buffer = (uintptr_t)NULL;
> > > + txn->data.ptr.offsets = (uintptr_t)NULL;
> > > + txn->offsets_size = 0;
> > > +
> > > + memset(&bwr, 0, sizeof(bwr));
> > > + bwr.write_buffer = (unsigned long)writebuf;
> > > + bwr.write_size = sizeof(writebuf[0]) + sizeof(*txn);
> > > +
> > > + bwr.read_size = sizeof(readbuf);
> > > + bwr.read_consumed = 0;
> > > + bwr.read_buffer = (uintptr_t)readbuf;
> > > +
> > > + result = ioctl(obj->handle, BINDER_WRITE_READ, &bwr);
> > > + if (result < 0) {
> > > + fprintf(stderr,
> > > + "CLIENT ioctl BINDER_WRITE_READ: %s\n",
> > > + strerror(errno));
> > > + exit(101);
> > > + }
> > > +
> > > + if (verbose)
> > > + printf("Client read_consumed: %lld\n",
> > > bwr.read_consumed);
> > > +
> > > + cmd = binder_parse(obj->handle, (uintptr_t)readbuf,
> > > + bwr.read_consumed,
> > > + "Client using Managers FD");
> > > +
> > > + if (cmd == BR_FAILED_REPLY ||
> > > + cmd == BR_DEAD_REPLY ||
> > > + cmd == BR_DEAD_BINDER) {
> > > + fprintf(stderr,
> > > + "Client using Managers received FD
> > > failed response\n");
> > > + exit(102);
> > > + }
> > > +}
> > > +
> > > +/* Parse response, reply as required and then return last CMD */
> > > +static int binder_parse(int fd, uintptr_t ptr, size_t size, char
> > > *text)
> > > +{
> > > + uintptr_t end = ptr + (uintptr_t)size;
> > > + uint32_t cmd;
> > > +
> > > + while (ptr < end) {
> > > + cmd = *(uint32_t *)ptr;
> > > + ptr += sizeof(uint32_t);
> > > +
> > > + if (verbose)
> > > + printf("%s command: %s\n", text,
> > > cmd_name(cmd));
> > > +
> > > + switch (cmd) {
> > > + case BR_NOOP:
> > > + break;
> > > + case BR_TRANSACTION_COMPLETE:
> > > + break;
> > > + case BR_INCREFS:
> > > + case BR_ACQUIRE:
> > > + case BR_RELEASE:
> > > + case BR_DECREFS:
> > > + ptr += sizeof(struct binder_ptr_cookie);
> > > + break;
> > > + case BR_TRANSACTION: {
> > > + struct binder_transaction_data *txn =
> > > + (struct binder_transaction_data
> > > *)ptr;
> > > +
> > > + if (verbose) {
> > > + printf("BR_TRANSACTION
> > > data:\n");
> > > + print_trans_data(txn);
> > > + }
> > > +
> > > + /* The manager sends reply that will
> > > contain its fd */
> > > + if (send_reply(fd, txn) < 0) {
> > > + fprintf(stderr, "send_reply()
> > > failed.\n");
> > > + return -1;
> > > + }
> > > + ptr += sizeof(*txn);
> > > + break;
> > > + }
> > > + case BR_REPLY: {
> > > + struct binder_transaction_data *txn =
> > > + (struct binder_transaction_data
> > > *)ptr;
> > > +
> > > + if (verbose) {
> > > + printf("BR_REPLY data:\n");
> > > + print_trans_data(txn);
> > > + }
> > > +
> > > + /* Client extracts the Manager fd, and
> > > responds */
> > > + extract_fd_and_respond(txn);
> > > + ptr += sizeof(*txn);
> > > + break;
> > > + }
> > > + case BR_DEAD_BINDER:
> > > + break;
> > > + case BR_FAILED_REPLY:
> > > + break;
> > > + case BR_DEAD_REPLY:
> > > + break;
> > > + case BR_ERROR:
> > > + ptr += sizeof(uint32_t);
> > > + break;
> > > + default:
> > > + if (verbose)
> > > + printf("%s Parsed unknown
> > > command: %d\n",
> > > + text, cmd);
> > > + return -1;
> > > + }
> > > + }
> > > +
> > > + return cmd;
> > > +}
> > > +
> > > +int main(int argc, char **argv)
> > > +{
> > > + int opt, option, result, fd, count;
> > > + uint32_t cmd;
> > > + pid_t pid;
> > > + char *driver = "/dev/binder";
> > > + char *context;
> > > + void *mapped;
> > > + size_t mapsize = 2048;
> > > + struct binder_write_read bwr;
> > > + struct flat_binder_object obj;
> > > + struct binder_transaction_data *txn;
> > > + unsigned int readbuf[32];
> > > + unsigned int writebuf[1024];
> > > +
> > > + target = 0; /* Only need one target - the Manager */
> > > + verbose = false;
> > > +
> > > + while ((opt = getopt(argc, argv, "v")) != -1) {
> > > + switch (opt) {
> > > + case 'v':
> > > + verbose = true;
> > > + break;
> > > + default:
> > > + usage(argv[0]);
> > > + }
> > > + }
> > > +
> > > + if ((argc - optind) != 1)
> > > + usage(argv[0]);
> > > +
> > > + if (!strcmp(argv[optind], "manager"))
> > > + option = 1;
> > > + else if (!strcmp(argv[optind], "client"))
> > > + option = 2;
> > > + else
> > > + usage(argv[0]);
> > > +
> > > + fd = open(driver, O_RDWR | O_CLOEXEC);
> > > + if (fd < 0) {
> > > + fprintf(stderr, "Cannot open %s error: %s\n",
> > > driver,
> > > + strerror(errno));
> > > + exit(1);
> > > + }
> > > +
> > > + /* Need this or "no VMA" error from kernel */
> > > + mapped = mmap(NULL, mapsize, PROT_READ, MAP_PRIVATE, fd,
> > > 0);
> > > + if (mapped == MAP_FAILED) {
> > > + fprintf(stderr, "mmap error: %s\n",
> > > strerror(errno));
> > > + close(fd);
> > > + exit(2);
> > > + }
> > > +
> > > + /* Get our context and pid */
> > > + result = getcon(&context);
> > > + if (result < 0) {
> > > + fprintf(stderr, "Failed to obtain SELinux
> > > context\n");
> > > + result = 3;
> > > + goto brexit;
> > > + }
> > > + pid = getpid();
> > > +
> > > + switch (option) {
> > > + case 1: /* manager */
> > > + if (verbose) {
> > > + printf("Manager PID: %d Process
> > > context:\n\t%s\n",
> > > + pid, context);
> > > + }
> > > +
> > > + result = ioctl(fd, BINDER_SET_CONTEXT_MGR, 0);
> > > + if (result < 0) {
> > > + fprintf(stderr,
> > > + "Failed to become context
> > > manager: %s\n",
> > > + strerror(errno));
> > > + result = 4;
> > > + goto brexit;
> > > + }
> > > +
> > > + readbuf[0] = BC_ENTER_LOOPER;
> > > + bwr.write_size = sizeof(readbuf[0]);
> > > + bwr.write_consumed = 0;
> > > + bwr.write_buffer = (uintptr_t)readbuf;
> > > +
> > > + bwr.read_size = 0;
> > > + bwr.read_consumed = 0;
> > > + bwr.read_buffer = 0;
> > > +
> > > + result = ioctl(fd, BINDER_WRITE_READ, &bwr);
> > > + if (result < 0) {
> > > + fprintf(stderr,
> > > + "Manager ioctl
> > > BINDER_WRITE_READ: %s\n",
> > > + strerror(errno));
> > > + result = 5;
> > > + goto brexit;
> > > + }
> > > +
> > > + while (true) {
> > > + bwr.read_size = sizeof(readbuf);
> > > + bwr.read_consumed = 0;
> > > + bwr.read_buffer = (uintptr_t)readbuf;
> > > +
> > > + result = ioctl(fd, BINDER_WRITE_READ,
> > > &bwr);
> > > + if (result < 0) {
> > > + fprintf(stderr,
> > > + "Manager ioctl
> > > BINDER_WRITE_READ: %s\n",
> > > + strerror(errno));
> > > + result = 6;
> > > + goto brexit;
> > > + }
> > > +
> > > + if (bwr.read_consumed == 0)
> > > + continue;
> > > +
> > > + if (verbose)
> > > + printf("Manager read_consumed:
> > > %lld\n",
> > > + bwr.read_consumed);
> > > +
> > > + cmd = binder_parse(fd,
> > > (uintptr_t)readbuf,
> > > + bwr.read_consumed,
> > > "Manager");
> > > + }
> > > + break;
> > > +
> > > + case 2: /* client */
> > > + if (verbose) {
> > > + printf("Client PID: %d Process
> > > context:\n\t%s\n",
> > > + pid, context);
> > > + }
> > > +
> > > + writebuf[0] = BC_TRANSACTION;
> > > + txn = (struct binder_transaction_data
> > > *)(&writebuf[1]);
> > > + memset(txn, 0, sizeof(*txn));
> > > + txn->target.handle = target;
> > > + txn->cookie = 0;
> > > + txn->code = 0;
> > > + txn->flags = TF_ACCEPT_FDS;
> > > +
> > > + memset(&obj, 0, sizeof(struct
> > > flat_binder_object));
> > > + obj.hdr.type = BINDER_TYPE_WEAK_BINDER;
> > > + obj.flags = 0x7f | FLAT_BINDER_FLAG_ACCEPTS_FDS;
> > > + obj.binder = target;
> > > + obj.handle = 0;
> > > + obj.cookie = 0;
> > > +
> > > + txn->data_size = sizeof(struct
> > > flat_binder_object);
> > > + txn->data.ptr.buffer = (uintptr_t)&obj;
> > > + txn->data.ptr.offsets = (uintptr_t)&obj +
> > > + sizeof(struct
> > > flat_binder_object);
> > > + txn->offsets_size = sizeof(binder_size_t);
> > > +
> > > + memset(&bwr, 0, sizeof(bwr));
> > > + bwr.write_buffer = (unsigned long)writebuf;
> > > + bwr.write_size = sizeof(writebuf[0]) +
> > > sizeof(*txn);
> > > +
> > > + /* Expect client to get max two responses:
> > > + * 1) From the above BC_TRANSACTION
> > > + * 2) The responding BC_REPLY from
> > > send_reply()
> > > + * unless an error.
> > > + */
> > > + count = 0;
> > > + while (count != 2) {
> > > + bwr.read_size = sizeof(readbuf);
> > > + bwr.read_consumed = 0;
> > > + bwr.read_buffer = (uintptr_t)readbuf;
> > > +
> > > + result = ioctl(fd, BINDER_WRITE_READ,
> > > &bwr);
> > > + if (result < 0) {
> > > + fprintf(stderr,
> > > + "Client ioctl
> > > BINDER_WRITE_READ: %s\n",
> > > + strerror(errno));
> > > + result = 8;
> > > + goto brexit;
> > > + }
> > > +
> > > + if (verbose)
> > > + printf("Client read_consumed:
> > > %lld\n",
> > > + bwr.read_consumed);
> > > +
> > > + cmd = binder_parse(fd,
> > > (uintptr_t)readbuf,
> > > + bwr.read_consumed,
> > > "Client");
> > > +
> > > + if (cmd == BR_FAILED_REPLY ||
> > > + cmd == BR_DEAD_REPLY ||
> > > + cmd == BR_DEAD_BINDER) {
> > > + result = 9;
> > > + goto brexit;
> > > + }
> > > + count++;
> > > + }
> > > + break;
> > > +
> > > + default:
> > > + result = -1;
> > > + }
> > > +
> > > +brexit:
> > > + free(context);
> > > + munmap(mapped, mapsize);
> > > + close(fd);
> > > +
> > > + return result;
> > > +}
> > >
>
>
