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.
> +
> 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.
> 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.
>
> 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?
> +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.
> +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.
>
> 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?
> + 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.
> +
> + # 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;
> +}
>
