[LTP] [PATCH v2] syscalls/prctl04.c: New test for prctl() with PR_{SET, GET}_SECCOMP
xuyang
xuyang2018.jy@cn.fujitsu.com
Thu May 23 04:49:34 CEST 2019
Hi cyril
I will send a v3 patch for this. Thanks for your review.
Kind Regards
Yang Xu
> 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.
>
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