Re: [PATCH] selinux_testsuite: Add socketpair test

[Stephen Smalley <sds@tycho.nsa.gov>]

On 12/4/19 9:32 AM, Richard Haines wrote:
> Test SO_PEERSEC for sockets created by socketpair(2) added in kernel 4.18
> 
> Signed-off-by: Richard Haines <richard_c_haines@btinternet.com>
> ---

> diff --git a/tests/unix_socket/Makefile b/tests/unix_socket/Makefile
> index 5266096..7770f0b 100644
> --- a/tests/unix_socket/Makefile
> +++ b/tests/unix_socket/Makefile
> @@ -2,6 +2,11 @@ TARGETS=client server
>   
>   LDLIBS+= -lselinux
>   
> +# Test SO_PEERSEC for sockets created by socketpair(2).
> +ifneq ($(shell ../kvercmp $$(uname -r) 4.18),-1)
> +	TARGETS += socketpair
> +endif
> +
>   all: $(TARGETS)
>   clean:
>   	rm -f $(TARGETS)

Wondering if we ought to unconditionally build all targets and only 
perform the kvercmp test in the test script itself, as we do in binder, 
inet_socket, keys, and sctp?  Only need to conditionalize the build if 
it won't build under older kernels.

> diff --git a/tests/unix_socket/socketpair.c b/tests/unix_socket/socketpair.c
> new file mode 100644
> index 0000000..50cd3fa
> --- /dev/null
> +++ b/tests/unix_socket/socketpair.c
> @@ -0,0 +1,190 @@
> +#include <stdlib.h>
> +#include <stdio.h>
> +#include <stddef.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <fcntl.h>
> +#include <errno.h>
> +#include <sys/types.h>
> +#include <sys/socket.h>
> +#include <selinux/selinux.h>
> +
> +#ifndef SO_PEERSEC
> +#define SO_PEERSEC 31
> +#endif
> +
> +#ifndef SCM_SECURITY
> +#define SCM_SECURITY 0x03
> +#endif
> +
> +void print_usage(char *progname)
> +{
> +	fprintf(stderr,
> +		"usage:  %s stream|dgram\n"
> +		"Where:\n\t"
> +		"stream     Use TCP protocol or:\n\t"
> +		"dgram      use UDP protocol.\n", progname);
> +	exit(-1);
> +}
> +
> +int run_parent(int sock, int type)
> +{
> +	int result, on = 1;
> +	char byte, peerlabel[256];
> +	socklen_t labellen = sizeof(peerlabel);
> +
> +	result = setsockopt(sock, SOL_SOCKET, SO_PASSSEC, &on, sizeof(on));
> +	if (result < 0) {
> +		perror("setsockopt: SO_PASSSEC");
> +		goto err;
> +	}
> +
> +	if (type == SOCK_STREAM) {
> +		result = read(sock, &byte, 1);
> +		if (result < 0) {
> +			perror("read");
> +			goto err;
> +		}
> +
> +		result = getsockopt(sock, SOL_SOCKET, SO_PEERSEC, peerlabel,
> +				    &labellen);
> +		if (result < 0) {
> +			perror("getsockopt: SO_PEERSEC");
> +			goto err;
> +		}
> +		printf("Parent got peer label=%s\n", peerlabel);
> +
> +		result = write(sock, peerlabel, sizeof(peerlabel));

You should be writing labellen bytes or strlen(peerlabel) bytes rather 
than sizeof(peerlabel); otherwise you are sending extra uninitialized 
bytes from the stack to the peer.  Looks like elsewhere we are sending 
strlen() of the label.