| /* | |
| * 32-bit syscall ABI conformance test. | |
| * | |
| * Copyright (c) 2015 Denys Vlasenko | |
| * | |
| * This program is free software; you can redistribute it and/or modify | |
| * it under the terms and conditions of the GNU General Public License, | |
| * version 2, as published by the Free Software Foundation. | |
| * | |
| * This program is distributed in the hope it will be useful, but | |
| * WITHOUT ANY WARRANTY; without even the implied warranty of | |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| * General Public License for more details. | |
| */ | |
| /* | |
| * Can be built statically: | |
| * gcc -Os -Wall -static -m32 test_syscall_vdso.c thunks_32.S | |
| */ | |
| #undef _GNU_SOURCE | |
| #define _GNU_SOURCE 1 | |
| #undef __USE_GNU | |
| #define __USE_GNU 1 | |
| #include <unistd.h> | |
| #include <stdlib.h> | |
| #include <string.h> | |
| #include <stdio.h> | |
| #include <signal.h> | |
| #include <sys/types.h> | |
| #include <sys/select.h> | |
| #include <sys/time.h> | |
| #include <elf.h> | |
| #include <sys/ptrace.h> | |
| #include <sys/wait.h> | |
| #if !defined(__i386__) | |
| int main(int argc, char **argv, char **envp) | |
| { | |
| printf("[SKIP]\tNot a 32-bit x86 userspace\n"); | |
| return 0; | |
| } | |
| #else | |
| long syscall_addr; | |
| long get_syscall(char **envp) | |
| { | |
| Elf32_auxv_t *auxv; | |
| while (*envp++ != NULL) | |
| continue; | |
| for (auxv = (void *)envp; auxv->a_type != AT_NULL; auxv++) | |
| if (auxv->a_type == AT_SYSINFO) | |
| return auxv->a_un.a_val; | |
| printf("[WARN]\tAT_SYSINFO not supplied\n"); | |
| return 0; | |
| } | |
| asm ( | |
| " .pushsection .text\n" | |
| " .global int80\n" | |
| "int80:\n" | |
| " int $0x80\n" | |
| " ret\n" | |
| " .popsection\n" | |
| ); | |
| extern char int80; | |
| struct regs64 { | |
| uint64_t rax, rbx, rcx, rdx; | |
| uint64_t rsi, rdi, rbp, rsp; | |
| uint64_t r8, r9, r10, r11; | |
| uint64_t r12, r13, r14, r15; | |
| }; | |
| struct regs64 regs64; | |
| int kernel_is_64bit; | |
| asm ( | |
| " .pushsection .text\n" | |
| " .code64\n" | |
| "get_regs64:\n" | |
| " push %rax\n" | |
| " mov $regs64, %eax\n" | |
| " pop 0*8(%rax)\n" | |
| " movq %rbx, 1*8(%rax)\n" | |
| " movq %rcx, 2*8(%rax)\n" | |
| " movq %rdx, 3*8(%rax)\n" | |
| " movq %rsi, 4*8(%rax)\n" | |
| " movq %rdi, 5*8(%rax)\n" | |
| " movq %rbp, 6*8(%rax)\n" | |
| " movq %rsp, 7*8(%rax)\n" | |
| " movq %r8, 8*8(%rax)\n" | |
| " movq %r9, 9*8(%rax)\n" | |
| " movq %r10, 10*8(%rax)\n" | |
| " movq %r11, 11*8(%rax)\n" | |
| " movq %r12, 12*8(%rax)\n" | |
| " movq %r13, 13*8(%rax)\n" | |
| " movq %r14, 14*8(%rax)\n" | |
| " movq %r15, 15*8(%rax)\n" | |
| " ret\n" | |
| "poison_regs64:\n" | |
| " movq $0x7f7f7f7f, %r8\n" | |
| " shl $32, %r8\n" | |
| " orq $0x7f7f7f7f, %r8\n" | |
| " movq %r8, %r9\n" | |
| " movq %r8, %r10\n" | |
| " movq %r8, %r11\n" | |
| " movq %r8, %r12\n" | |
| " movq %r8, %r13\n" | |
| " movq %r8, %r14\n" | |
| " movq %r8, %r15\n" | |
| " ret\n" | |
| " .code32\n" | |
| " .popsection\n" | |
| ); | |
| extern void get_regs64(void); | |
| extern void poison_regs64(void); | |
| extern unsigned long call64_from_32(void (*function)(void)); | |
| void print_regs64(void) | |
| { | |
| if (!kernel_is_64bit) | |
| return; | |
| printf("ax:%016llx bx:%016llx cx:%016llx dx:%016llx\n", regs64.rax, regs64.rbx, regs64.rcx, regs64.rdx); | |
| printf("si:%016llx di:%016llx bp:%016llx sp:%016llx\n", regs64.rsi, regs64.rdi, regs64.rbp, regs64.rsp); | |
| printf(" 8:%016llx 9:%016llx 10:%016llx 11:%016llx\n", regs64.r8 , regs64.r9 , regs64.r10, regs64.r11); | |
| printf("12:%016llx 13:%016llx 14:%016llx 15:%016llx\n", regs64.r12, regs64.r13, regs64.r14, regs64.r15); | |
| } | |
| int check_regs64(void) | |
| { | |
| int err = 0; | |
| int num = 8; | |
| uint64_t *r64 = ®s64.r8; | |
| if (!kernel_is_64bit) | |
| return 0; | |
| do { | |
| if (*r64 == 0x7f7f7f7f7f7f7f7fULL) | |
| continue; /* register did not change */ | |
| if (syscall_addr != (long)&int80) { | |
| /* | |
| * Non-INT80 syscall entrypoints are allowed to clobber R8+ regs: | |
| * either clear them to 0, or for R11, load EFLAGS. | |
| */ | |
| if (*r64 == 0) | |
| continue; | |
| if (num == 11) { | |
| printf("[NOTE]\tR11 has changed:%016llx - assuming clobbered by SYSRET insn\n", *r64); | |
| continue; | |
| } | |
| } else { | |
| /* INT80 syscall entrypoint can be used by | |
| * 64-bit programs too, unlike SYSCALL/SYSENTER. | |
| * Therefore it must preserve R12+ | |
| * (they are callee-saved registers in 64-bit C ABI). | |
| * | |
| * This was probably historically not intended, | |
| * but R8..11 are clobbered (cleared to 0). | |
| * IOW: they are the only registers which aren't | |
| * preserved across INT80 syscall. | |
| */ | |
| if (*r64 == 0 && num <= 11) | |
| continue; | |
| } | |
| printf("[FAIL]\tR%d has changed:%016llx\n", num, *r64); | |
| err++; | |
| } while (r64++, ++num < 16); | |
| if (!err) | |
| printf("[OK]\tR8..R15 did not leak kernel data\n"); | |
| return err; | |
| } | |
| int nfds; | |
| fd_set rfds; | |
| fd_set wfds; | |
| fd_set efds; | |
| struct timespec timeout; | |
| sigset_t sigmask; | |
| struct { | |
| sigset_t *sp; | |
| int sz; | |
| } sigmask_desc; | |
| void prep_args() | |
| { | |
| nfds = 42; | |
| FD_ZERO(&rfds); | |
| FD_ZERO(&wfds); | |
| FD_ZERO(&efds); | |
| FD_SET(0, &rfds); | |
| FD_SET(1, &wfds); | |
| FD_SET(2, &efds); | |
| timeout.tv_sec = 0; | |
| timeout.tv_nsec = 123; | |
| sigemptyset(&sigmask); | |
| sigaddset(&sigmask, SIGINT); | |
| sigaddset(&sigmask, SIGUSR2); | |
| sigaddset(&sigmask, SIGRTMAX); | |
| sigmask_desc.sp = &sigmask; | |
| sigmask_desc.sz = 8; /* bytes */ | |
| } | |
| static void print_flags(const char *name, unsigned long r) | |
| { | |
| static const char *bitarray[] = { | |
| "\n" ,"c\n" ,/* Carry Flag */ | |
| "0 " ,"1 " ,/* Bit 1 - always on */ | |
| "" ,"p " ,/* Parity Flag */ | |
| "0 " ,"3? " , | |
| "" ,"a " ,/* Auxiliary carry Flag */ | |
| "0 " ,"5? " , | |
| "" ,"z " ,/* Zero Flag */ | |
| "" ,"s " ,/* Sign Flag */ | |
| "" ,"t " ,/* Trap Flag */ | |
| "" ,"i " ,/* Interrupt Flag */ | |
| "" ,"d " ,/* Direction Flag */ | |
| "" ,"o " ,/* Overflow Flag */ | |
| "0 " ,"1 " ,/* I/O Privilege Level (2 bits) */ | |
| "0" ,"1" ,/* I/O Privilege Level (2 bits) */ | |
| "" ,"n " ,/* Nested Task */ | |
| "0 " ,"15? ", | |
| "" ,"r " ,/* Resume Flag */ | |
| "" ,"v " ,/* Virtual Mode */ | |
| "" ,"ac " ,/* Alignment Check/Access Control */ | |
| "" ,"vif ",/* Virtual Interrupt Flag */ | |
| "" ,"vip ",/* Virtual Interrupt Pending */ | |
| "" ,"id " ,/* CPUID detection */ | |
| NULL | |
| }; | |
| const char **bitstr; | |
| int bit; | |
| printf("%s=%016lx ", name, r); | |
| bitstr = bitarray + 42; | |
| bit = 21; | |
| if ((r >> 22) != 0) | |
| printf("(extra bits are set) "); | |
| do { | |
| if (bitstr[(r >> bit) & 1][0]) | |
| fputs(bitstr[(r >> bit) & 1], stdout); | |
| bitstr -= 2; | |
| bit--; | |
| } while (bit >= 0); | |
| } | |
| int run_syscall(void) | |
| { | |
| long flags, bad_arg; | |
| prep_args(); | |
| if (kernel_is_64bit) | |
| call64_from_32(poison_regs64); | |
| /*print_regs64();*/ | |
| asm("\n" | |
| /* Try 6-arg syscall: pselect. It should return quickly */ | |
| " push %%ebp\n" | |
| " mov $308, %%eax\n" /* PSELECT */ | |
| " mov nfds, %%ebx\n" /* ebx arg1 */ | |
| " mov $rfds, %%ecx\n" /* ecx arg2 */ | |
| " mov $wfds, %%edx\n" /* edx arg3 */ | |
| " mov $efds, %%esi\n" /* esi arg4 */ | |
| " mov $timeout, %%edi\n" /* edi arg5 */ | |
| " mov $sigmask_desc, %%ebp\n" /* %ebp arg6 */ | |
| " push $0x200ed7\n" /* set almost all flags */ | |
| " popf\n" /* except TF, IOPL, NT, RF, VM, AC, VIF, VIP */ | |
| " call *syscall_addr\n" | |
| /* Check that registers are not clobbered */ | |
| " pushf\n" | |
| " pop %%eax\n" | |
| " cld\n" | |
| " cmp nfds, %%ebx\n" /* ebx arg1 */ | |
| " mov $1, %%ebx\n" | |
| " jne 1f\n" | |
| " cmp $rfds, %%ecx\n" /* ecx arg2 */ | |
| " mov $2, %%ebx\n" | |
| " jne 1f\n" | |
| " cmp $wfds, %%edx\n" /* edx arg3 */ | |
| " mov $3, %%ebx\n" | |
| " jne 1f\n" | |
| " cmp $efds, %%esi\n" /* esi arg4 */ | |
| " mov $4, %%ebx\n" | |
| " jne 1f\n" | |
| " cmp $timeout, %%edi\n" /* edi arg5 */ | |
| " mov $5, %%ebx\n" | |
| " jne 1f\n" | |
| " cmpl $sigmask_desc, %%ebp\n" /* %ebp arg6 */ | |
| " mov $6, %%ebx\n" | |
| " jne 1f\n" | |
| " mov $0, %%ebx\n" | |
| "1:\n" | |
| " pop %%ebp\n" | |
| : "=a" (flags), "=b" (bad_arg) | |
| : | |
| : "cx", "dx", "si", "di" | |
| ); | |
| if (kernel_is_64bit) { | |
| memset(®s64, 0x77, sizeof(regs64)); | |
| call64_from_32(get_regs64); | |
| /*print_regs64();*/ | |
| } | |
| /* | |
| * On paravirt kernels, flags are not preserved across syscalls. | |
| * Thus, we do not consider it a bug if some are changed. | |
| * We just show ones which do. | |
| */ | |
| if ((0x200ed7 ^ flags) != 0) { | |
| print_flags("[WARN]\tFlags before", 0x200ed7); | |
| print_flags("[WARN]\tFlags after", flags); | |
| print_flags("[WARN]\tFlags change", (0x200ed7 ^ flags)); | |
| } | |
| if (bad_arg) { | |
| printf("[FAIL]\targ#%ld clobbered\n", bad_arg); | |
| return 1; | |
| } | |
| printf("[OK]\tArguments are preserved across syscall\n"); | |
| return check_regs64(); | |
| } | |
| int run_syscall_twice() | |
| { | |
| int exitcode = 0; | |
| long sv; | |
| if (syscall_addr) { | |
| printf("[RUN]\tExecuting 6-argument 32-bit syscall via VDSO\n"); | |
| exitcode = run_syscall(); | |
| } | |
| sv = syscall_addr; | |
| syscall_addr = (long)&int80; | |
| printf("[RUN]\tExecuting 6-argument 32-bit syscall via INT 80\n"); | |
| exitcode += run_syscall(); | |
| syscall_addr = sv; | |
| return exitcode; | |
| } | |
| void ptrace_me() | |
| { | |
| pid_t pid; | |
| fflush(NULL); | |
| pid = fork(); | |
| if (pid < 0) | |
| exit(1); | |
| if (pid == 0) { | |
| /* child */ | |
| if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) != 0) | |
| exit(0); | |
| raise(SIGSTOP); | |
| return; | |
| } | |
| /* parent */ | |
| printf("[RUN]\tRunning tests under ptrace\n"); | |
| while (1) { | |
| int status; | |
| pid = waitpid(-1, &status, __WALL); | |
| if (WIFEXITED(status)) | |
| exit(WEXITSTATUS(status)); | |
| if (WIFSIGNALED(status)) | |
| exit(WTERMSIG(status)); | |
| if (pid <= 0 || !WIFSTOPPED(status)) /* paranoia */ | |
| exit(255); | |
| /* | |
| * Note: we do not inject sig = WSTOPSIG(status). | |
| * We probably should, but careful: do not inject SIGTRAP | |
| * generated by syscall entry/exit stops. | |
| * That kills the child. | |
| */ | |
| ptrace(PTRACE_SYSCALL, pid, 0L, 0L /*sig*/); | |
| } | |
| } | |
| int main(int argc, char **argv, char **envp) | |
| { | |
| int exitcode = 0; | |
| int cs; | |
| asm("\n" | |
| " movl %%cs, %%eax\n" | |
| : "=a" (cs) | |
| ); | |
| kernel_is_64bit = (cs == 0x23); | |
| if (!kernel_is_64bit) | |
| printf("[NOTE]\tNot a 64-bit kernel, won't test R8..R15 leaks\n"); | |
| /* This only works for non-static builds: | |
| * syscall_addr = dlsym(dlopen("linux-gate.so.1", RTLD_NOW), "__kernel_vsyscall"); | |
| */ | |
| syscall_addr = get_syscall(envp); | |
| exitcode += run_syscall_twice(); | |
| ptrace_me(); | |
| exitcode += run_syscall_twice(); | |
| return exitcode; | |
| } | |
| #endif |