[LTP] [PATCH] syscalls/prctl04.c: New test for prctl() with PR_{SET, GET}_SECCOMP
Cyril Hrubis
chrubis@suse.cz
Mon May 20 15:04:07 CEST 2019
Hi!
> diff --git a/configure.ac b/configure.ac
> index fad8f8396..c858aff42 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -46,6 +46,7 @@ AC_CHECK_HEADERS([ \
> linux/mempolicy.h \
> linux/module.h \
> linux/netlink.h \
> + linux/seccomp.h \
> linux/userfaultfd.h \
> mm.h \
> netinet/sctp.h \
> diff --git a/include/lapi/prctl.h b/include/lapi/prctl.h
> index 6db8a6480..c3612e643 100644
> --- a/include/lapi/prctl.h
> +++ b/include/lapi/prctl.h
> @@ -14,4 +14,9 @@
> # define PR_GET_CHILD_SUBREAPER 37
> #endif
>
> +#ifndef PR_SET_SECCOMP
> +# define PR_GET_SECCOMP 21
> +# define PR_SET_SECCOMP 22
> +#endif
> +
> #endif /* LAPI_PRCTL_H__ */
> diff --git a/include/lapi/seccomp.h b/include/lapi/seccomp.h
> new file mode 100644
> index 000000000..1e5bc3933
> --- /dev/null
> +++ b/include/lapi/seccomp.h
> @@ -0,0 +1,36 @@
> +// 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>
> +
> +/* 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 /* _LAPI_SECCOMP_H */
> 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..e3ba69af3
> --- /dev/null
> +++ b/testcases/kernel/syscalls/prctl/prctl04.c
> @@ -0,0 +1,262 @@
> +// 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"
> +#ifdef HAVE_LINUX_SECCOMP_H
> +#include <linux/seccomp.h>
> +#else
> +#include <lapi/seccomp.h>
> +#endif
This ifdef should be in the lapi/seccomp.h instead.
I.e. the test should only include lapi/seccomp.h and should not care if
linux/seccomp.h is present or not.
> +#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 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) {
> + if (TST_ERR == EINVAL) {
> + tst_res(TCONF,
> + "prctl(PR_SET_SECCOMP) doesn't support "
> + "SECCOMP_MODE_STRICT");
> + } else {
> + tst_res(TFAIL | TTERRNO,
> + "prctl(PR_SET_SECCOMP) sets "
> + "SECCOMP_MODE_STRICT failed");
> + }
> + return;
> + }
> + if (val == 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");
> + }
> + if (val == 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)");
> + }
> + if (val == 3) {
> + close(fd);
> + tst_res(TFAIL,
> + "SECCOMP_MODE_STRICT permits close(2) unexpectdly");
> + }
This is way too ugly, if nothing else we should use switch() here.
> + tst_syscall(__NR_exit, 0);
> +}
> +
> +static void check_filter_mode(int val)
> +{
> + int childpid;
> + int childstatus;
> + 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 == EFAULT)
> + tst_res(TFAIL, "the strict prog is an invalid address");
> + else
> + tst_res(TFAIL | TERRNO,
> + "prctl(PR_SET_SECCOMP) sets strict filter "
> + "failed");
> + return;
> + }
> + if (val == 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");
> + }
> + if (val == 2) {
> + close(fd);
> + tst_res(TPASS, "SECCOMP_MODE_FILTER permits close(2)");
> + }
> + if (val == 3)
> + exit(0);
> + if (val == 4) {
> + childpid = fork();
> + if (childpid == 0) {
> + tst_res(TPASS, "SECCOMP_MODE_FILTER permits fork(2)");
> + exit(0);
> + } else {
> + 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");
> + }
> + }
Here as well, use switch().
Also it would make sense to put the more complicated bodies, for
instance case val == 4 into a separate function.
> + tst_syscall(__NR_exit, 0);
> +}
> +
> +static void verify_prctl(void)
> +{
> + int pid;
> + int status;
> +
> + TEST(prctl(PR_GET_SECCOMP));
> + if (TST_RET == -1) {
> + if (TST_ERR == EINVAL) {
> + tst_res(TCONF,
> + "prctl() doesn't support PR_GET_SECCOMP");
> + } else {
> + tst_res(TFAIL | TTERRNO,
> + "prctl(PR_GET_SECCOMP) failed");
> + }
> + return;
> + }
> + tst_res(TPASS, "prctl(PR_GET_SECCOMP) succeed");
> +
> + /*call get_seccomp when in stric mode ,it should be killed*/
> + pid = SAFE_FORK();
> + if (pid == 0) {
> + check_strict_mode(1);
> + } else {
> + SAFE_WAITPID(pid, &status, 0);
> + if (WIFSIGNALED(status) && WTERMSIG(status) == SIGKILL)
> + tst_res(TPASS,
> + "SECCOMP_MODE_STRICT doesn't permit "
> + "GET_SECCOMP call");
> + }
> +
> + /*positive check in secure computing mode*/
> + pid = SAFE_FORK();
> + if (pid == 0) {
> + check_strict_mode(2);
> + } else {
> + SAFE_WAITPID(pid, &status, 0);
> + if (WIFSIGNALED(status) && WTERMSIG(status) == SIGKILL)
> + tst_res(TFAIL,
> + "SECCOMP_MODE_STRICT doesn't permit "
> + "read(2) write(2) and _exit(2)");
> + }
> +
> + /*negative check in secure computing mode*/
> + pid = SAFE_FORK();
> + if (pid == 0) {
> + check_strict_mode(3);
> + } else {
> + SAFE_WAITPID(pid, &status, 0);
> + if (WIFSIGNALED(status) && WTERMSIG(status) == SIGKILL)
> + tst_res(TPASS,
> + "SECCOMP_MODE_STRICT doesn't permit close(2)");
> + }
> +
> + /*call get_seccomp in filter mode should be killed by SIGSYS signal*/
> + pid = SAFE_FORK();
> + if (pid == 0) {
> + check_filter_mode(1);
> + } else {
> + SAFE_WAITPID(pid, &status, 0);
> + if (WIFSIGNALED(status) && WTERMSIG(status) == SIGSYS)
> + tst_res(TPASS,
> + "SECCOMP_MODE_FILTER doestn't permit "
> + "GET_SECCOMP call");
> + }
> +
> + /*positive check in SECCOMP_MODE_FILTER*/
> + pid = SAFE_FORK();
> + if (pid == 0) {
> + check_filter_mode(2);
> + } else {
> + SAFE_WAITPID(pid, &status, 0);
> + if (WIFSIGNALED(status) && WTERMSIG(status) == SIGSYS)
> + tst_res(TFAIL,
> + "SECCOMP_MODE_FILTER doesn't permit close(2)");
> + }
> +
> + /*negative check in SECCOMP_MODE_FILTER*/
> + pid = SAFE_FORK();
> + if (pid == 0) {
> + check_filter_mode(3);
> + } else {
> + SAFE_WAITPID(pid, &status, 0);
> + if (WIFSIGNALED(status) && WTERMSIG(status) == SIGSYS)
> + tst_res(TPASS,
> + "SECCOMP_MODE_FILTER doesn't permit exit()");
> + else
> + tst_res(TFAIL,
> + "SECCOMP_MODE_FILTER permits exit() "
> + "unexpectdly");
> + }
> +
> + pid = SAFE_FORK();
> + if (pid == 0) {
> + check_filter_mode(4);
> + } else {
> + SAFE_WAITPID(pid, &status, 0);
> + if (WIFSIGNALED(status) && WTERMSIG(status) == SIGSYS)
> + tst_res(TFAIL,
> + "SECCOMP_MODE_FILTER fork failed "
> + "unexpectdly");
This is a minor, but multiline statements should be enclosed in a curly
braces accodingly to LKML and also string constants shouldn't be split
into multiple lines, so this should be:
if (WIFSIGNALED(status) && WTERMSIG(status) == SIGSYS) {
tst_res(TFAIL,
"SECCOMP_MODE_FILTER fork failed unexpectdly");
}
Also the else branch is useless since the function check_filter_mode()
calls exit.
So we can simply do:
pid = SAFE_FORK();
if (pid == 0)
check_fitler_mode(4);
SAFE_WAITPID(...);
> + }
> +}
You are doing several different tests in this function, can we split
this and use .test and .tcnt instead of .test_all?
> +static struct tst_test test = {
> + .test_all = verify_prctl,
> + .forks_child = 1,
> + .needs_tmpdir = 1,
> + .needs_root = 1,
> +};
Otherwise it looks good.
--
Cyril Hrubis
chrubis@suse.cz
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