503 lines
11 KiB
C
503 lines
11 KiB
C
/*
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* Copyright (c) 2019 Alexey Dobriyan <adobriyan@gmail.com>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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/*
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* Fork and exec tiny 1 page executable which precisely controls its VM.
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* Test /proc/$PID/maps
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* Test /proc/$PID/smaps
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* Test /proc/$PID/smaps_rollup
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* Test /proc/$PID/statm
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*
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* FIXME require CONFIG_TMPFS which can be disabled
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* FIXME test other values from "smaps"
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* FIXME support other archs
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*/
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#undef NDEBUG
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#include <assert.h>
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#include <errno.h>
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#include <sched.h>
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#include <signal.h>
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#include <stdbool.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#include <sys/mount.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/wait.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <sys/syscall.h>
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#include <sys/uio.h>
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#include <linux/kdev_t.h>
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#include <sys/time.h>
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#include <sys/resource.h>
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#include "../kselftest.h"
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static inline long sys_execveat(int dirfd, const char *pathname, char **argv, char **envp, int flags)
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{
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return syscall(SYS_execveat, dirfd, pathname, argv, envp, flags);
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}
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static void make_private_tmp(void)
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{
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if (unshare(CLONE_NEWNS) == -1) {
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if (errno == ENOSYS || errno == EPERM) {
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exit(4);
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}
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exit(1);
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}
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if (mount(NULL, "/", NULL, MS_PRIVATE|MS_REC, NULL) == -1) {
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exit(1);
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}
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if (mount(NULL, "/tmp", "tmpfs", 0, NULL) == -1) {
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exit(1);
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}
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}
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static pid_t pid = -1;
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static void ate(void)
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{
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if (pid > 0) {
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kill(pid, SIGTERM);
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}
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}
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struct elf64_hdr {
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uint8_t e_ident[16];
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uint16_t e_type;
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uint16_t e_machine;
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uint32_t e_version;
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uint64_t e_entry;
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uint64_t e_phoff;
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uint64_t e_shoff;
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uint32_t e_flags;
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uint16_t e_ehsize;
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uint16_t e_phentsize;
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uint16_t e_phnum;
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uint16_t e_shentsize;
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uint16_t e_shnum;
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uint16_t e_shstrndx;
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};
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struct elf64_phdr {
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uint32_t p_type;
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uint32_t p_flags;
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uint64_t p_offset;
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uint64_t p_vaddr;
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uint64_t p_paddr;
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uint64_t p_filesz;
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uint64_t p_memsz;
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uint64_t p_align;
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};
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#ifdef __x86_64__
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#define PAGE_SIZE 4096
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#define VADDR (1UL << 32)
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#define MAPS_OFFSET 73
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#define syscall 0x0f, 0x05
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#define mov_rdi(x) \
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0x48, 0xbf, \
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(x)&0xff, ((x)>>8)&0xff, ((x)>>16)&0xff, ((x)>>24)&0xff, \
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((x)>>32)&0xff, ((x)>>40)&0xff, ((x)>>48)&0xff, ((x)>>56)&0xff
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#define mov_rsi(x) \
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0x48, 0xbe, \
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(x)&0xff, ((x)>>8)&0xff, ((x)>>16)&0xff, ((x)>>24)&0xff, \
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((x)>>32)&0xff, ((x)>>40)&0xff, ((x)>>48)&0xff, ((x)>>56)&0xff
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#define mov_eax(x) \
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0xb8, (x)&0xff, ((x)>>8)&0xff, ((x)>>16)&0xff, ((x)>>24)&0xff
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static const uint8_t payload[] = {
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/* Casually unmap stack, vDSO and everything else. */
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/* munmap */
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mov_rdi(VADDR + 4096),
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mov_rsi((1ULL << 47) - 4096 - VADDR - 4096),
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mov_eax(11),
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syscall,
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/* Ping parent. */
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/* write(0, &c, 1); */
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0x31, 0xff, /* xor edi, edi */
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0x48, 0x8d, 0x35, 0x00, 0x00, 0x00, 0x00, /* lea rsi, [rip] */
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0xba, 0x01, 0x00, 0x00, 0x00, /* mov edx, 1 */
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mov_eax(1),
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syscall,
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/* 1: pause(); */
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mov_eax(34),
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syscall,
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0xeb, 0xf7, /* jmp 1b */
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};
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static int make_exe(const uint8_t *payload, size_t len)
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{
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struct elf64_hdr h;
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struct elf64_phdr ph;
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struct iovec iov[3] = {
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{&h, sizeof(struct elf64_hdr)},
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{&ph, sizeof(struct elf64_phdr)},
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{(void *)payload, len},
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};
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int fd, fd1;
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char buf[64];
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memset(&h, 0, sizeof(h));
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h.e_ident[0] = 0x7f;
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h.e_ident[1] = 'E';
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h.e_ident[2] = 'L';
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h.e_ident[3] = 'F';
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h.e_ident[4] = 2;
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h.e_ident[5] = 1;
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h.e_ident[6] = 1;
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h.e_ident[7] = 0;
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h.e_type = 2;
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h.e_machine = 0x3e;
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h.e_version = 1;
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h.e_entry = VADDR + sizeof(struct elf64_hdr) + sizeof(struct elf64_phdr);
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h.e_phoff = sizeof(struct elf64_hdr);
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h.e_shoff = 0;
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h.e_flags = 0;
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h.e_ehsize = sizeof(struct elf64_hdr);
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h.e_phentsize = sizeof(struct elf64_phdr);
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h.e_phnum = 1;
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h.e_shentsize = 0;
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h.e_shnum = 0;
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h.e_shstrndx = 0;
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memset(&ph, 0, sizeof(ph));
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ph.p_type = 1;
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ph.p_flags = (1<<2)|1;
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ph.p_offset = 0;
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ph.p_vaddr = VADDR;
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ph.p_paddr = 0;
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ph.p_filesz = sizeof(struct elf64_hdr) + sizeof(struct elf64_phdr) + len;
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ph.p_memsz = sizeof(struct elf64_hdr) + sizeof(struct elf64_phdr) + len;
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ph.p_align = 4096;
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fd = openat(AT_FDCWD, "/tmp", O_WRONLY|O_EXCL|O_TMPFILE, 0700);
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if (fd == -1) {
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exit(1);
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}
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if (writev(fd, iov, 3) != sizeof(struct elf64_hdr) + sizeof(struct elf64_phdr) + len) {
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exit(1);
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}
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/* Avoid ETXTBSY on exec. */
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snprintf(buf, sizeof(buf), "/proc/self/fd/%u", fd);
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fd1 = open(buf, O_RDONLY|O_CLOEXEC);
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close(fd);
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return fd1;
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}
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#endif
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/*
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* 0: vsyscall VMA doesn't exist vsyscall=none
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* 1: vsyscall VMA is --xp vsyscall=xonly
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* 2: vsyscall VMA is r-xp vsyscall=emulate
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*/
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static volatile int g_vsyscall;
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static const char *str_vsyscall;
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static const char str_vsyscall_0[] = "";
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static const char str_vsyscall_1[] =
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"ffffffffff600000-ffffffffff601000 --xp 00000000 00:00 0 [vsyscall]\n";
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static const char str_vsyscall_2[] =
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"ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]\n";
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#ifdef __x86_64__
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static void sigaction_SIGSEGV(int _, siginfo_t *__, void *___)
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{
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_exit(g_vsyscall);
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}
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/*
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* vsyscall page can't be unmapped, probe it directly.
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*/
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static void vsyscall(void)
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{
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pid_t pid;
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int wstatus;
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pid = fork();
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if (pid < 0) {
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fprintf(stderr, "fork, errno %d\n", errno);
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exit(1);
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}
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if (pid == 0) {
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struct rlimit rlim = {0, 0};
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(void)setrlimit(RLIMIT_CORE, &rlim);
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/* Hide "segfault at ffffffffff600000" messages. */
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struct sigaction act;
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memset(&act, 0, sizeof(struct sigaction));
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act.sa_flags = SA_SIGINFO;
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act.sa_sigaction = sigaction_SIGSEGV;
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(void)sigaction(SIGSEGV, &act, NULL);
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g_vsyscall = 0;
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/* gettimeofday(NULL, NULL); */
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uint64_t rax = 0xffffffffff600000;
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asm volatile (
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"call *%[rax]"
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: [rax] "+a" (rax)
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: "D" (NULL), "S" (NULL)
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: "rcx", "r11"
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);
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g_vsyscall = 1;
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*(volatile int *)0xffffffffff600000UL;
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g_vsyscall = 2;
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exit(g_vsyscall);
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}
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waitpid(pid, &wstatus, 0);
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if (WIFEXITED(wstatus)) {
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g_vsyscall = WEXITSTATUS(wstatus);
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} else {
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fprintf(stderr, "error: wstatus %08x\n", wstatus);
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exit(1);
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}
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}
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int main(void)
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{
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int pipefd[2];
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int exec_fd;
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vsyscall();
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switch (g_vsyscall) {
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case 0:
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str_vsyscall = str_vsyscall_0;
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break;
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case 1:
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str_vsyscall = str_vsyscall_1;
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break;
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case 2:
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str_vsyscall = str_vsyscall_2;
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break;
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default:
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abort();
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}
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atexit(ate);
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make_private_tmp();
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/* Reserve fd 0 for 1-byte pipe ping from child. */
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close(0);
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if (open("/", O_RDONLY|O_DIRECTORY|O_PATH) != 0) {
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return 1;
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}
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exec_fd = make_exe(payload, sizeof(payload));
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if (pipe(pipefd) == -1) {
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return 1;
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}
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if (dup2(pipefd[1], 0) != 0) {
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return 1;
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}
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pid = fork();
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if (pid == -1) {
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return 1;
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}
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if (pid == 0) {
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sys_execveat(exec_fd, "", NULL, NULL, AT_EMPTY_PATH);
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return 1;
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}
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char _;
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if (read(pipefd[0], &_, 1) != 1) {
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return 1;
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}
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struct stat st;
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if (fstat(exec_fd, &st) == -1) {
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return 1;
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}
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/* Generate "head -n1 /proc/$PID/maps" */
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char buf0[256];
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memset(buf0, ' ', sizeof(buf0));
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int len = snprintf(buf0, sizeof(buf0),
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"%08lx-%08lx r-xp 00000000 %02lx:%02lx %llu",
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VADDR, VADDR + PAGE_SIZE,
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MAJOR(st.st_dev), MINOR(st.st_dev),
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(unsigned long long)st.st_ino);
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buf0[len] = ' ';
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snprintf(buf0 + MAPS_OFFSET, sizeof(buf0) - MAPS_OFFSET,
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"/tmp/#%llu (deleted)\n", (unsigned long long)st.st_ino);
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/* Test /proc/$PID/maps */
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{
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const size_t len = strlen(buf0) + strlen(str_vsyscall);
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char buf[256];
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ssize_t rv;
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int fd;
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snprintf(buf, sizeof(buf), "/proc/%u/maps", pid);
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fd = open(buf, O_RDONLY);
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if (fd == -1) {
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return 1;
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}
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rv = read(fd, buf, sizeof(buf));
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assert(rv == len);
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assert(memcmp(buf, buf0, strlen(buf0)) == 0);
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if (g_vsyscall > 0) {
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assert(memcmp(buf + strlen(buf0), str_vsyscall, strlen(str_vsyscall)) == 0);
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}
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}
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/* Test /proc/$PID/smaps */
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{
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char buf[4096];
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ssize_t rv;
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int fd;
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snprintf(buf, sizeof(buf), "/proc/%u/smaps", pid);
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fd = open(buf, O_RDONLY);
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if (fd == -1) {
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return 1;
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}
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rv = read(fd, buf, sizeof(buf));
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assert(0 <= rv && rv <= sizeof(buf));
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assert(rv >= strlen(buf0));
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assert(memcmp(buf, buf0, strlen(buf0)) == 0);
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#define RSS1 "Rss: 4 kB\n"
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#define RSS2 "Rss: 0 kB\n"
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#define PSS1 "Pss: 4 kB\n"
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#define PSS2 "Pss: 0 kB\n"
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assert(memmem(buf, rv, RSS1, strlen(RSS1)) ||
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memmem(buf, rv, RSS2, strlen(RSS2)));
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assert(memmem(buf, rv, PSS1, strlen(PSS1)) ||
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memmem(buf, rv, PSS2, strlen(PSS2)));
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static const char *S[] = {
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"Size: 4 kB\n",
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"KernelPageSize: 4 kB\n",
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"MMUPageSize: 4 kB\n",
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"Anonymous: 0 kB\n",
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"AnonHugePages: 0 kB\n",
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"Shared_Hugetlb: 0 kB\n",
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"Private_Hugetlb: 0 kB\n",
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"Locked: 0 kB\n",
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};
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int i;
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for (i = 0; i < ARRAY_SIZE(S); i++) {
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assert(memmem(buf, rv, S[i], strlen(S[i])));
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}
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if (g_vsyscall > 0) {
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assert(memmem(buf, rv, str_vsyscall, strlen(str_vsyscall)));
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}
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}
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/* Test /proc/$PID/smaps_rollup */
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{
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char bufr[256];
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memset(bufr, ' ', sizeof(bufr));
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len = snprintf(bufr, sizeof(bufr),
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"%08lx-%08lx ---p 00000000 00:00 0",
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VADDR, VADDR + PAGE_SIZE);
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bufr[len] = ' ';
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snprintf(bufr + MAPS_OFFSET, sizeof(bufr) - MAPS_OFFSET,
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"[rollup]\n");
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char buf[1024];
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ssize_t rv;
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int fd;
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snprintf(buf, sizeof(buf), "/proc/%u/smaps_rollup", pid);
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fd = open(buf, O_RDONLY);
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if (fd == -1) {
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return 1;
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}
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rv = read(fd, buf, sizeof(buf));
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assert(0 <= rv && rv <= sizeof(buf));
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assert(rv >= strlen(bufr));
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assert(memcmp(buf, bufr, strlen(bufr)) == 0);
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assert(memmem(buf, rv, RSS1, strlen(RSS1)) ||
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memmem(buf, rv, RSS2, strlen(RSS2)));
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assert(memmem(buf, rv, PSS1, strlen(PSS1)) ||
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memmem(buf, rv, PSS2, strlen(PSS2)));
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static const char *S[] = {
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"Anonymous: 0 kB\n",
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"AnonHugePages: 0 kB\n",
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"Shared_Hugetlb: 0 kB\n",
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"Private_Hugetlb: 0 kB\n",
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"Locked: 0 kB\n",
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};
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int i;
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for (i = 0; i < ARRAY_SIZE(S); i++) {
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assert(memmem(buf, rv, S[i], strlen(S[i])));
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}
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}
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/* Test /proc/$PID/statm */
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{
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char buf[64];
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ssize_t rv;
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int fd;
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snprintf(buf, sizeof(buf), "/proc/%u/statm", pid);
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fd = open(buf, O_RDONLY);
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if (fd == -1) {
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return 1;
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}
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rv = read(fd, buf, sizeof(buf));
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assert(rv == 7 * 2);
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assert(buf[0] == '1'); /* ->total_vm */
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assert(buf[1] == ' ');
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assert(buf[2] == '0' || buf[2] == '1'); /* rss */
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assert(buf[3] == ' ');
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assert(buf[4] == '0' || buf[2] == '1'); /* file rss */
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assert(buf[5] == ' ');
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assert(buf[6] == '1'); /* ELF executable segments */
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assert(buf[7] == ' ');
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assert(buf[8] == '0');
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assert(buf[9] == ' ');
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assert(buf[10] == '0'); /* ->data_vm + ->stack_vm */
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assert(buf[11] == ' ');
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assert(buf[12] == '0');
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assert(buf[13] == '\n');
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}
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return 0;
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}
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#else
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int main(void)
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{
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return 4;
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}
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#endif
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