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We were relying on luck to make the mapping before our first mmap() be inaccessible. Let's make it explicit.
94 lines
4.9 KiB
C++
94 lines
4.9 KiB
C++
/*
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* Copyright (c) 2018-2022, Andreas Kling <kling@serenityos.org>
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* Copyright (c) 2021, Andrew Kaster <akaster@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/Assertions.h>
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#include <AK/Format.h>
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#include <AK/Types.h>
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#include <LibTest/TestCase.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <sys/mman.h>
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#include <unistd.h>
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#define EXPECT_OK(syscall, address, size) \
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do { \
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errno = 0; \
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rc = syscall(fd, (void*)(address), (size_t)(size)); \
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EXPECT(rc >= 0); \
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if (rc < 0) { \
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warnln("Expected success: " #syscall "({:p}, {}), got rc={}, errno={}", (void*)(address), (size_t)(size), rc, errno); \
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} \
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} while (0)
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#define EXPECT_EFAULT(syscall, address, size) \
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do { \
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errno = 0; \
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rc = syscall(fd, (void*)(address), (size_t)(size)); \
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EXPECT(rc < 0); \
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EXPECT_EQ(errno, EFAULT); \
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if (rc >= 0 || errno != EFAULT) { \
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warnln("Expected EFAULT: " #syscall "({:p}, {}), got rc={}, errno={}", (void*)(address), (size_t)(size), rc, errno); \
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} \
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} while (0)
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TEST_CASE(test_efault)
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{
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int fd = open("/dev/zero", O_RDONLY);
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int rc = -1;
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// Make an inaccessible hole before the next mapping.
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(void)mmap(nullptr, 4096, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
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// Test a one-page mapping (4KB)
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u8* one_page = (u8*)mmap(nullptr, 4096, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
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VERIFY(one_page);
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EXPECT_OK(read, one_page, 4096);
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EXPECT_EFAULT(read, one_page, 4097);
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EXPECT_EFAULT(read, one_page - 1, 4096);
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// Make an unused hole mapping to create some inaccessible distance between our one and two-page mappings.
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(void)mmap(nullptr, 16384, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
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// Test a two-page mapping (8KB)
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u8* two_page = (u8*)mmap(nullptr, 8192, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
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VERIFY(two_page);
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EXPECT_OK(read, two_page, 4096);
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EXPECT_OK(read, two_page + 4096, 4096);
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EXPECT_OK(read, two_page, 8192);
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EXPECT_OK(read, two_page + 4095, 4097);
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EXPECT_OK(read, two_page + 1, 8191);
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EXPECT_EFAULT(read, two_page, 8193);
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EXPECT_EFAULT(read, two_page - 1, 1);
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// Check validation of pages between the first and last address.
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ptrdiff_t distance = two_page - one_page;
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EXPECT_EFAULT(read, one_page, (u32)distance + 1024);
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constexpr auto user_range_ceiling = (sizeof(void*) == 4 ? 0xbe000000u : 0x1ffe000000);
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u8* jerk_page = nullptr;
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// Test every kernel page just because.
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constexpr auto kernel_range_ceiling = (sizeof(void*) == 4 ? 0xffffffffu : 0x203fffffff);
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for (u64 kernel_address = user_range_ceiling; kernel_address <= kernel_range_ceiling; kernel_address += PAGE_SIZE) {
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jerk_page = (u8*)mmap((void*)kernel_address, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, 0, 0);
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EXPECT_EQ(jerk_page, MAP_FAILED);
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EXPECT_EQ(errno, EFAULT);
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}
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// Test the page just below where the user VM ends.
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jerk_page = (u8*)mmap((void*)(user_range_ceiling - PAGE_SIZE), PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, 0, 0);
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EXPECT_EQ(jerk_page, (u8*)(user_range_ceiling - PAGE_SIZE));
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EXPECT_OK(read, jerk_page, PAGE_SIZE);
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EXPECT_EFAULT(read, jerk_page, PAGE_SIZE + 1);
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// Test something that would wrap around the 2^32 mark.
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EXPECT_EFAULT(read, jerk_page, 0x50000000);
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}
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