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selftests/seccomp: Enhance per-arch ptrace syscall skip tests
commited5f13261c
upstream. Passing EPERM during syscall skipping was confusing since the test wasn't actually exercising the errno evaluation -- it was just passing a literal "1" (EPERM). Instead, expand the tests to check both direct value returns (positive, 45000 in this case), and errno values (negative, -ESRCH in this case) to check both fake success and fake failure during syscall skipping. Reported-by: Colin Ian King <colin.king@canonical.com> Fixes:a33b2d0359
("selftests/seccomp: Add tests for basic ptrace actions") Cc: stable@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Shuah Khan <shuah@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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1 changed files with 57 additions and 15 deletions
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@ -1554,7 +1554,16 @@ TEST_F(TRACE_poke, getpid_runs_normally)
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#ifdef SYSCALL_NUM_RET_SHARE_REG
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# define EXPECT_SYSCALL_RETURN(val, action) EXPECT_EQ(-1, action)
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#else
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# define EXPECT_SYSCALL_RETURN(val, action) EXPECT_EQ(val, action)
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# define EXPECT_SYSCALL_RETURN(val, action) \
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do { \
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errno = 0; \
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if (val < 0) { \
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EXPECT_EQ(-1, action); \
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EXPECT_EQ(-(val), errno); \
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} else { \
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EXPECT_EQ(val, action); \
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} \
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} while (0)
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#endif
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/* Use PTRACE_GETREGS and PTRACE_SETREGS when available. This is useful for
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@ -1593,7 +1602,7 @@ int get_syscall(struct __test_metadata *_metadata, pid_t tracee)
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/* Architecture-specific syscall changing routine. */
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void change_syscall(struct __test_metadata *_metadata,
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pid_t tracee, int syscall)
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pid_t tracee, int syscall, int result)
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{
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int ret;
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ARCH_REGS regs;
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@ -1652,7 +1661,7 @@ void change_syscall(struct __test_metadata *_metadata,
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#ifdef SYSCALL_NUM_RET_SHARE_REG
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TH_LOG("Can't modify syscall return on this architecture");
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#else
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regs.SYSCALL_RET = EPERM;
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regs.SYSCALL_RET = result;
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#endif
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#ifdef HAVE_GETREGS
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@ -1680,14 +1689,19 @@ void tracer_syscall(struct __test_metadata *_metadata, pid_t tracee,
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case 0x1002:
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/* change getpid to getppid. */
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EXPECT_EQ(__NR_getpid, get_syscall(_metadata, tracee));
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change_syscall(_metadata, tracee, __NR_getppid);
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change_syscall(_metadata, tracee, __NR_getppid, 0);
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break;
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case 0x1003:
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/* skip gettid. */
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/* skip gettid with valid return code. */
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EXPECT_EQ(__NR_gettid, get_syscall(_metadata, tracee));
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change_syscall(_metadata, tracee, -1);
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change_syscall(_metadata, tracee, -1, 45000);
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break;
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case 0x1004:
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/* skip openat with error. */
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EXPECT_EQ(__NR_openat, get_syscall(_metadata, tracee));
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change_syscall(_metadata, tracee, -1, -ESRCH);
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break;
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case 0x1005:
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/* do nothing (allow getppid) */
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EXPECT_EQ(__NR_getppid, get_syscall(_metadata, tracee));
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break;
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@ -1720,9 +1734,11 @@ void tracer_ptrace(struct __test_metadata *_metadata, pid_t tracee,
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nr = get_syscall(_metadata, tracee);
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if (nr == __NR_getpid)
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change_syscall(_metadata, tracee, __NR_getppid);
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change_syscall(_metadata, tracee, __NR_getppid, 0);
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if (nr == __NR_gettid)
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change_syscall(_metadata, tracee, -1, 45000);
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if (nr == __NR_openat)
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change_syscall(_metadata, tracee, -1);
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change_syscall(_metadata, tracee, -1, -ESRCH);
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}
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FIXTURE_DATA(TRACE_syscall) {
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@ -1739,8 +1755,10 @@ FIXTURE_SETUP(TRACE_syscall)
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BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_TRACE | 0x1002),
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BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_gettid, 0, 1),
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BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_TRACE | 0x1003),
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BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_getppid, 0, 1),
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BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_openat, 0, 1),
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BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_TRACE | 0x1004),
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BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, __NR_getppid, 0, 1),
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BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_TRACE | 0x1005),
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BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
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};
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@ -1788,15 +1806,26 @@ TEST_F(TRACE_syscall, ptrace_syscall_redirected)
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EXPECT_NE(self->mypid, syscall(__NR_getpid));
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}
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TEST_F(TRACE_syscall, ptrace_syscall_dropped)
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TEST_F(TRACE_syscall, ptrace_syscall_errno)
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{
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/* Swap SECCOMP_RET_TRACE tracer for PTRACE_SYSCALL tracer. */
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teardown_trace_fixture(_metadata, self->tracer);
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self->tracer = setup_trace_fixture(_metadata, tracer_ptrace, NULL,
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true);
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/* Tracer should skip the open syscall, resulting in EPERM. */
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EXPECT_SYSCALL_RETURN(EPERM, syscall(__NR_openat));
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/* Tracer should skip the open syscall, resulting in ESRCH. */
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EXPECT_SYSCALL_RETURN(-ESRCH, syscall(__NR_openat));
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}
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TEST_F(TRACE_syscall, ptrace_syscall_faked)
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{
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/* Swap SECCOMP_RET_TRACE tracer for PTRACE_SYSCALL tracer. */
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teardown_trace_fixture(_metadata, self->tracer);
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self->tracer = setup_trace_fixture(_metadata, tracer_ptrace, NULL,
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true);
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/* Tracer should skip the gettid syscall, resulting fake pid. */
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EXPECT_SYSCALL_RETURN(45000, syscall(__NR_gettid));
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}
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TEST_F(TRACE_syscall, syscall_allowed)
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@ -1829,7 +1858,21 @@ TEST_F(TRACE_syscall, syscall_redirected)
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EXPECT_NE(self->mypid, syscall(__NR_getpid));
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}
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TEST_F(TRACE_syscall, syscall_dropped)
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TEST_F(TRACE_syscall, syscall_errno)
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{
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long ret;
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ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
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ASSERT_EQ(0, ret);
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ret = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &self->prog, 0, 0);
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ASSERT_EQ(0, ret);
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/* openat has been skipped and an errno return. */
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EXPECT_SYSCALL_RETURN(-ESRCH, syscall(__NR_openat));
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}
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TEST_F(TRACE_syscall, syscall_faked)
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{
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long ret;
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@ -1840,8 +1883,7 @@ TEST_F(TRACE_syscall, syscall_dropped)
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ASSERT_EQ(0, ret);
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/* gettid has been skipped and an altered return value stored. */
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EXPECT_SYSCALL_RETURN(EPERM, syscall(__NR_gettid));
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EXPECT_NE(self->mytid, syscall(__NR_gettid));
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EXPECT_SYSCALL_RETURN(45000, syscall(__NR_gettid));
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}
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TEST_F(TRACE_syscall, skip_after_RET_TRACE)
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