From mboxrd@z Thu Jan  1 00:00:00 1970
From: Cyril Hrubis <chrubis@suse.cz>
Date: Wed, 22 May 2019 14:36:57 +0200
Subject: [LTP] [PATCH v2] syscalls/prctl04.c: New test for prctl() with
 PR_{SET, GET}_SECCOMP
In-Reply-To: <1558520056-2257-1-git-send-email-xuyang2018.jy@cn.fujitsu.com>
References: <20190520130407.GB27675@rei.lan>
 <1558520056-2257-1-git-send-email-xuyang2018.jy@cn.fujitsu.com>
Message-ID: <20190522123657.GB7912@rei.lan>
List-Id: <ltp.lists.linux.it>
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To: ltp@lists.linux.it

Hi!
> diff --git a/include/lapi/seccomp.h b/include/lapi/seccomp.h
> new file mode 100644
> index 000000000..eead53c48
> --- /dev/null
> +++ b/include/lapi/seccomp.h
> @@ -0,0 +1,40 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2019 FUJITSU LIMITED. All rights reserved.
> + * Author: Yang Xu <xuyang2018.jy@cn.fujitsu.com>
> + */
> +#ifndef LAPI_SECCOMP_H__
> +# define _LAPI_SECCOMP_H
> +
> +#include <linux/types.h>
> +
> +#ifdef HAVE_LINUX_SECCOMP_H
> +#include <linux/seccomp.h>
> +#else
> +/* Valid values for seccomp.mode and prctl(PR_SET_SECCOMP, <mode>) */
> +#define SECCOMP_MODE_DISABLED   0
> +#define SECCOMP_MODE_STRICT     1
> +#define SECCOMP_MODE_FILTER     2
> +
> +#define SECCOMP_RET_KILL_THREAD  0x00000000U /* kill the thread */
> +#define SECCOMP_RET_KILL         SECCOMP_RET_KILL_THREAD
> +#define SECCOMP_RET_ALLOW        0x7fff0000U /* allow */
> +
> +/**
> + * struct seccomp_data - the format the BPF program executes over.
> + * @nr: the system call number
> + * @arch: indicates system call convention as an AUDIT_ARCH_* value
> + *        as defined in <linux/audit.h>.
> + * @instruction_pointer: at the time of the system call.
> + * @args: up to 6 system call arguments always stored as 64-bit values
> + * regardless of the architecture.
> + */
> +struct seccomp_data {
> +	int nr;
> +	__u32 arch;
> +	__u64 instruction_pointer;
> +	__u64 args[6];
> +};
> +
> +#endif /* HAVE_LINUX_SECCOMP_H*/
> +#endif /* _LAPI_SECCOMP_H */

The ifdefs could be made a bit more readable by proper indentation as:

#ifndef FOO_H__
#define FOO_H__

# include <header.h>

# ifdef HAVE_BAR
#  include <bar.h>
# else
#  define BAR1
#  define BAR2

# endif
#endif /* FOO_H__ */

But that is very minor.

> diff --git a/runtest/syscalls b/runtest/syscalls
> index 2b8ca719b..51bff2990 100644
> --- a/runtest/syscalls
> +++ b/runtest/syscalls
> @@ -863,6 +863,7 @@ ppoll01 ppoll01
>  prctl01 prctl01
>  prctl02 prctl02
>  prctl03 prctl03
> +prctl04 prctl04
>  
>  pread01 pread01
>  pread01_64 pread01_64
> diff --git a/testcases/kernel/syscalls/prctl/.gitignore b/testcases/kernel/syscalls/prctl/.gitignore
> index 2f46a9a12..1c3da3052 100644
> --- a/testcases/kernel/syscalls/prctl/.gitignore
> +++ b/testcases/kernel/syscalls/prctl/.gitignore
> @@ -1,3 +1,4 @@
>  /prctl01
>  /prctl02
>  /prctl03
> +/prctl04
> diff --git a/testcases/kernel/syscalls/prctl/prctl04.c b/testcases/kernel/syscalls/prctl/prctl04.c
> new file mode 100644
> index 000000000..9acd2c6fb
> --- /dev/null
> +++ b/testcases/kernel/syscalls/prctl/prctl04.c
> @@ -0,0 +1,229 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2019 FUJITSU LIMITED. All rights reserved.
> + * Author: Yang Xu <xuyang2018.jy@cn.fujitsu.com>
> + *
> + * Test PR_GET_SECCOMP and PR_SET_SECCOMP of prctl(2).
> + * 1) If PR_SET_SECCOMP sets the SECCOMP_MODE_STRICT for the calling thread,
> + *    the only system call that the thread is permitted to make are read(2),
> + *    write(2),_exit(2)(but not exit_group(2)), and sigreturn(2).  Other
> + *    system calls result in the delivery of a SIGKILL signal. This operation
> + *    is available only if the kernel is configured with CONFIG_SECCOMP enabled.
> + * 2) If PR_SET_SECCOMP sets the SECCOMP_MODE_FILTER for the calling thread,
> + *    the system calls allowed are defined by a pointer to a Berkeley Packet
> + *    Filter. Other system calls result int the delivery of a SIGSYS signal
> + *    with SECCOMP_RET_KILL. The SECCOMP_SET_MODE_FILTER operation is available
> + *    only if the kernel is configured with CONFIG_SECCOMP_FILTER enabled.
> + * 3) If SECCOMP_MODE_FILTER filters permit fork(2), then the seccomp mode
> + *    is inherited by children created by fork(2).
> + */
> +
> +#include <errno.h>
> +#include <signal.h>
> +#include <sys/prctl.h>
> +#include <sys/wait.h>
> +#include <sys/types.h>
> +#include <linux/filter.h>
> +#include <unistd.h>
> +#include <stdlib.h>
> +#include <stddef.h>
> +#include "tst_test.h"
> +#include "lapi/syscalls.h"
> +#include "lapi/prctl.h"
> +#include "config.h"
> +#include "lapi/seccomp.h"
> +
> +#define FNAME "filename"
> +
> +static const struct sock_filter  strict_filter[] = {
> +	BPF_STMT(BPF_LD | BPF_W | BPF_ABS, (offsetof (struct seccomp_data, nr))),
> +
> +	BPF_JUMP(BPF_JMP | BPF_JEQ, __NR_close, 5, 0),
> +	BPF_JUMP(BPF_JMP | BPF_JEQ, __NR_exit,  4, 0),
> +	BPF_JUMP(BPF_JMP | BPF_JEQ, __NR_wait4, 3, 0),
> +	BPF_JUMP(BPF_JMP | BPF_JEQ, __NR_write, 2, 0),
> +	BPF_JUMP(BPF_JMP | BPF_JEQ, __NR_clone, 1, 0),
> +
> +	BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_KILL),
> +	BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_ALLOW)
> +};
> +
> +static const struct sock_fprog  strict = {
> +	.len = (unsigned short)ARRAY_SIZE(strict_filter),
> +	.filter = (struct sock_filter *)strict_filter
> +};
> +
> +static void check_strict_mode(int);
> +static void check_filter_mode(int);
> +
> +static struct tcase {
> +	void (*func_check)();
> +	int pass_flag;
> +	int val;
> +	int exp_signal;
> +	char *message;
> +} tcases[] = {
> +	{check_strict_mode, 1, 1, SIGKILL,
> +	"SECCOMP_MODE_STRICT doesn't permit GET_SECCOMP call"},
> +
> +	{check_strict_mode, 0, 2, SIGKILL,
> +	"SECCOMP_MODE_STRICT doesn't permit read(2) write(2) and _exit(2)"},
> +
> +	{check_strict_mode, 1, 3, SIGKILL,
> +	"SECCOMP_MODE_STRICT doesn't permit close(2)"},
> +
> +	{check_filter_mode, 1, 1, SIGSYS,
> +	"SECCOMP_MODE_FILTER doestn't permit GET_SECCOMP call"},
> +
> +	{check_filter_mode, 0, 2, SIGSYS,
> +	"SECCOMP_MODE_FILTER doesn't permit close(2)"},
> +
> +	{check_filter_mode, 1, 3, SIGSYS,
> +	"SECCOMP_MODE_FILTER doesn't permit exit()"},
> +
> +	{check_filter_mode, 0, 4, SIGSYS,
> +	"SECCOMP_MODE_FILTER doesn't permit exit()"}
> +};
> +
> +static void check_filter_mode_inherit(void)
> +{
> +	int childpid;
> +	int childstatus;
> +
> +	childpid = fork();
> +	if (childpid == 0) {
> +		tst_res(TPASS, "SECCOMP_MODE_FILTER permits fork(2)");
> +		exit(0);
> +	}
> +
> +	wait4(childpid, &childstatus, 0, NULL);
> +	if (WIFSIGNALED(childstatus) && WTERMSIG(childstatus) == SIGSYS)
> +		tst_res(TPASS,
> +			"SECCOMP_MODE_FILTER has been inherited by child");
> +	else
> +		tst_res(TFAIL,
> +			"SECCOMP_MODE_FILTER isn't been inherited by child");
> +}
> +
> +static void check_strict_mode(int val)
> +{
> +	int fd;
> +	char buf[2];
> +
> +	fd = SAFE_OPEN(FNAME, O_RDWR | O_CREAT, 0666);
> +
> +	TEST(prctl(PR_SET_SECCOMP, SECCOMP_MODE_STRICT));
> +	if (TST_RET == -1) {
> +		tst_res(TFAIL | TTERRNO,
> +			"prctl(PR_SET_SECCOMP) sets SECCOMP_MODE_STRICT failed");
> +		return;
> +	}
> +
> +	switch (val) {
> +	case 1:	{
> +		tst_res(TPASS,
> +			"prctl(PR_SET_SECCOMP) sets SECCOMP_MODE_STRICT succeed");
> +		prctl(PR_GET_SECCOMP);
> +		tst_res(TFAIL, "prctl(PR_GET_SECCOMP) succeed unexpectedly");
> +	break;
> +	}

There is no need to enclose the case switches between curly braces
unless you need to declare variables there.

> +	case 2: {
> +		SAFE_WRITE(1, fd, "a", 1);
> +		SAFE_READ(0, fd, buf, 1);
> +		tst_res(TPASS,
> +			"SECCOMP_MODE_STRICT permits read(2) write(2) and _exit(2)");
> +	break;
> +	}
> +	case 3: {
> +		close(fd);
> +		tst_res(TFAIL,
> +			"SECCOMP_MODE_STRICT permits close(2) unexpectdly");
> +	break;
> +	}
> +	}
> +
> +	tst_syscall(__NR_exit, 0);
> +}
> +
> +static void check_filter_mode(int val)
> +{
> +	int fd;
> +
> +	fd = SAFE_OPEN(FNAME, O_RDWR | O_CREAT, 0666);
> +
> +	TEST(prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &strict));
> +	if (TST_RET == -1) {
> +		if (TST_ERR == EINVAL)
> +			tst_res(TCONF,
> +				"kernel doesn't support SECCOMP_MODE_FILTER");
> +		else
> +			tst_res(TFAIL | TERRNO,
> +				"prctl(PR_SET_SECCOMP) sets strict filter failed");
> +		return;
> +	}
> +
> +	switch (val) {
> +	case 1: {
> +		tst_res(TPASS,
> +			"prctl(PR_SET_SECCOMP) sets strict filter succeed");
> +		prctl(PR_GET_SECCOMP);
> +		tst_res(TFAIL, "prctl(PR_GET_SECCOMP) succeed unexpectedly");
> +	break;
> +	}
> +	case 2: {
> +		close(fd);
> +		tst_res(TPASS, "SECCOMP_MODE_FILTER permits close(2)");
> +	break;
> +	}
> +	case 3:
> +		exit(0);
> +	break;
> +	case 4:
> +		check_filter_mode_inherit();
> +	break;
> +	}
> +	tst_syscall(__NR_exit, 0);
> +}
> +
> +static void verify_prctl(unsigned int n)
> +{
> +	int pid;
> +	int status;
> +	struct tcase *tc = &tcases[n];
> +
> +	pid = SAFE_FORK();
> +	if (pid == 0) {
> +		tc->func_check(tc->val);
> +	} else {
> +		SAFE_WAITPID(pid, &status, 0);
> +		if (WIFSIGNALED(status) && WTERMSIG(status) == tc->exp_signal) {
> +			if (tc->pass_flag)
> +				tst_res(TPASS, "%s", tc->message);
> +			else
> +				tst_res(TFAIL, "%s", tc->message);
> +			return;
> +		}
> +
> +		if (n == 5)
> +			tst_res(TFAIL,
> +				"SECCOMP_MODE_FILTER permits exit() unexpectdly");
                                                                            ^
									   Typo

Depending on the value of n here is wrong, this code will unexpectedly
fail to work if someone adds testcases to the tcases array.

You can at least reuse the pass_flag and set it to 2 for this case, then
you can do if (tc->pass_flag == 2) here instead.

> +	}
> +}
> +
> +static void setup(void)
> +{
> +	TEST(prctl(PR_GET_SECCOMP));
> +	if (TST_RET == 0)
> +		tst_res(TINFO, "kernel support PR_GET/SET_SECCOMP");
> +	if (TST_ERR == EINVAL)
> +		tst_brk(TBROK, "kernel doesn't support PR_GET/SET_SECCOMP");
                          ^
			  Shouldn't this be TCONF?

Also we should handle other error cases, so maybe:

	if (TST_RET == 0) {
		tst_res(TINFO, ...);
		return;
	}

	if (TST_ERR == EINVAL)
		tst_brk(TCONF, ...);

	tst_brk(TBROK | TTERRNO, ...);

> +}
> +
> +static struct tst_test test = {
> +	.setup = setup,
> +	.test = verify_prctl,
> +	.tcnt = ARRAY_SIZE(tcases),
> +	.forks_child = 1,
> +	.needs_tmpdir = 1,
> +	.needs_root = 1,
> +};

Other than these minor nits the test looks good to me.

-- 
Cyril Hrubis
chrubis@suse.cz