X-Git-Url: http://mj.ucw.cz/gitweb/?a=blobdiff_plain;ds=sidebyside;f=box%2Fbox.c;h=65734db9b3c7a2ce6d1db0eae071c9c248dd6b7e;hb=9e030699033caacbda788bc1a02cfa076c65fb71;hp=892cc53eb9b8bee98fb369f7b4e8810a342375ad;hpb=e707d3466b88637003cdfa7463300df8f47aa845;p=moe.git diff --git a/box/box.c b/box/box.c index 892cc53..65734db 100644 --- a/box/box.c +++ b/box/box.c @@ -1,7 +1,7 @@ /* - * A Simple Sandbox for MO-Eval + * A Simple Sandbox for Moe * - * (c) 2001--2008 Martin Mares + * (c) 2001--2010 Martin Mares */ #define _LARGEFILE64_SOURCE @@ -13,6 +13,7 @@ #include #include #include +#include #include #include #include @@ -231,16 +232,18 @@ static unsigned char syscall_action[NUM_ACTIONS] = { S(open) = A_FILENAME, S(creat) = A_FILENAME, S(unlink) = A_FILENAME, - S(oldstat) = A_FILENAME, S(access) = A_FILENAME, - S(oldlstat) = A_FILENAME, S(truncate) = A_FILENAME, S(stat) = A_FILENAME, S(lstat) = A_FILENAME, + S(readlink) = A_FILENAME, +#ifndef CONFIG_BOX_AMD64 + S(oldstat) = A_FILENAME, + S(oldlstat) = A_FILENAME, S(truncate64) = A_FILENAME, S(stat64) = A_FILENAME, S(lstat64) = A_FILENAME, - S(readlink) = A_FILENAME, +#endif // Syscalls permitted always S(exit) = A_YES | A_SAMPLE_MEM, @@ -250,7 +253,6 @@ static unsigned char syscall_action[NUM_ACTIONS] = { S(lseek) = A_YES, S(getpid) = A_YES, S(getuid) = A_YES, - S(oldfstat) = A_YES, S(dup) = A_YES, S(brk) = A_YES, S(getgid) = A_YES, @@ -260,7 +262,6 @@ static unsigned char syscall_action[NUM_ACTIONS] = { S(ftruncate) = A_YES, S(fstat) = A_YES, S(personality) = A_YES, - S(_llseek) = A_YES, S(readv) = A_YES, S(writev) = A_YES, S(getresuid) = A_YES, @@ -271,12 +272,8 @@ static unsigned char syscall_action[NUM_ACTIONS] = { S(pread) = A_YES, S(pwrite) = A_YES, #endif - S(ftruncate64) = A_YES, - S(fstat64) = A_YES, S(fcntl) = A_YES, - S(fcntl64) = A_YES, S(mmap) = A_YES, - S(mmap2) = A_YES, S(munmap) = A_YES, S(ioctl) = A_YES, S(uname) = A_YES, @@ -285,32 +282,29 @@ static unsigned char syscall_action[NUM_ACTIONS] = { S(get_thread_area) = A_YES, S(set_tid_address) = A_YES, S(exit_group) = A_YES | A_SAMPLE_MEM, +#ifndef CONFIG_BOX_AMD64 + S(oldfstat) = A_YES, + S(ftruncate64) = A_YES, + S(_llseek) = A_YES, + S(fstat64) = A_YES, + S(fcntl64) = A_YES, + S(mmap2) = A_YES, +#endif // Syscalls permitted only in liberal mode S(time) = A_YES | A_LIBERAL, S(alarm) = A_YES | A_LIBERAL, S(pause) = A_YES | A_LIBERAL, - S(signal) = A_YES | A_LIBERAL, S(fchmod) = A_YES | A_LIBERAL, - S(sigaction) = A_YES | A_LIBERAL, - S(sgetmask) = A_YES | A_LIBERAL, - S(ssetmask) = A_YES | A_LIBERAL, - S(sigsuspend) = A_YES | A_LIBERAL, - S(sigpending) = A_YES | A_LIBERAL, S(getrlimit) = A_YES | A_LIBERAL, S(getrusage) = A_YES | A_LIBERAL, - S(ugetrlimit) = A_YES | A_LIBERAL, S(gettimeofday) = A_YES | A_LIBERAL, S(select) = A_YES | A_LIBERAL, - S(readdir) = A_YES | A_LIBERAL, S(setitimer) = A_YES | A_LIBERAL, S(getitimer) = A_YES | A_LIBERAL, - S(sigreturn) = A_YES | A_LIBERAL | A_NO_RETVAL, S(mprotect) = A_YES | A_LIBERAL, - S(sigprocmask) = A_YES | A_LIBERAL, S(getdents) = A_YES | A_LIBERAL, S(getdents64) = A_YES | A_LIBERAL, - S(_newselect) = A_YES | A_LIBERAL, S(fdatasync) = A_YES | A_LIBERAL, S(mremap) = A_YES | A_LIBERAL, S(poll) = A_YES | A_LIBERAL, @@ -324,6 +318,20 @@ static unsigned char syscall_action[NUM_ACTIONS] = { S(rt_sigqueueinfo) = A_YES | A_LIBERAL, S(rt_sigsuspend) = A_YES | A_LIBERAL, S(_sysctl) = A_YES | A_LIBERAL, +#ifndef CONFIG_BOX_AMD64 + S(sigaction) = A_YES | A_LIBERAL, + S(sgetmask) = A_YES | A_LIBERAL, + S(ssetmask) = A_YES | A_LIBERAL, + S(sigsuspend) = A_YES | A_LIBERAL, + S(sigpending) = A_YES | A_LIBERAL, + S(sigreturn) = A_YES | A_LIBERAL | A_NO_RETVAL, + S(sigprocmask) = A_YES | A_LIBERAL, + S(ugetrlimit) = A_YES | A_LIBERAL, + S(readdir) = A_YES | A_LIBERAL, + S(signal) = A_YES | A_LIBERAL, + S(_newselect) = A_YES | A_LIBERAL, +#endif + #undef S }; @@ -587,10 +595,128 @@ setup_environment(void) return env; } +/*** Low-level parsing of syscalls ***/ + +#ifdef CONFIG_BOX_AMD64 +typedef uint64_t arg_t; +#else +typedef uint32_t arg_t; +#endif + +struct syscall_args { + arg_t sys; + arg_t arg1, arg2, arg3; + arg_t result; + struct user user; +}; + +static int read_user_mem(arg_t addr, char *buf, int len) +{ + static int mem_fd; + + if (!mem_fd) + { + char memname[64]; + sprintf(memname, "/proc/%d/mem", (int) box_pid); + mem_fd = open(memname, O_RDONLY); + if (mem_fd < 0) + die("open(%s): %m", memname); + } + if (lseek64(mem_fd, addr, SEEK_SET) < 0) + die("lseek64(mem): %m"); + return read(mem_fd, buf, len); +} + +#ifdef CONFIG_BOX_AMD64 + +static void +get_syscall_args(struct syscall_args *a, int is_exit) +{ + if (ptrace(PTRACE_GETREGS, box_pid, NULL, &a->user) < 0) + die("ptrace(PTRACE_GETREGS): %m"); + a->sys = a->user.regs.orig_rax; + a->arg1 = a->user.regs.rdi; + a->arg2 = a->user.regs.rsi; + a->arg3 = a->user.regs.rdx; + a->result = a->user.regs.rax; + + /* + * CAVEAT: We have to check carefully that this is a real 64-bit syscall. + * We test whether the process runs in 64-bit mode, but surprisingly this + * is not enough: a 64-bit process can still issue the INT 0x80 instruction + * which performs a 32-bit syscall. Currently, the only known way how to + * detect this situation is to inspect the instruction code (the kernel + * keeps a syscall type flag internally, but it is not accessible from + * user space). Hopefully, there is no instruction whose suffix is the + * code of the SYSCALL instruction. Sometimes, one would wish the + * instruction codes to be unique even when read backwards :) + */ + + if (is_exit) + return; + + switch (a->user.regs.cs) + { + case 0x23: + err("FO: Forbidden 32-bit mode syscall"); + case 0x33: + break; + default: + err("XX: Unknown code segment %04jx", (intmax_t) a->user.regs.cs); + } + + uint16_t instr; + if (read_user_mem(a->user.regs.rip-2, (char *) &instr, 2) != 2) + err("FO: Cannot read syscall instruction"); + switch (instr) + { + case 0x050f: + break; + case 0x80cd: + err("FO: Forbidden 32-bit syscall in 64-bit mode"); + default: + err("FO: Unknown syscall instruction %04x", instr); + } +} + +static void +set_syscall_nr(struct syscall_args *a, arg_t sys) +{ + a->sys = sys; + a->user.regs.orig_rax = sys; + if (ptrace(PTRACE_SETREGS, box_pid, NULL, &a->user) < 0) + die("ptrace(PTRACE_SETREGS): %m"); +} + +#else + +static void +get_syscall_args(struct syscall_args *a, int is_exit UNUSED) +{ + if (ptrace(PTRACE_GETREGS, box_pid, NULL, &a->user) < 0) + die("ptrace(PTRACE_GETREGS): %m"); + a->sys = a->user.regs.orig_eax; + a->arg1 = a->user.regs.ebx; + a->arg2 = a->user.regs.ecx; + a->arg3 = a->user.regs.edx; + a->result = a->user.regs.eax; +} + +static void +set_syscall_nr(struct syscall_args *a, arg_t sys) +{ + a->sys = sys; + a->user.regs.orig_eax = sys; + if (ptrace(PTRACE_SETREGS, box_pid, NULL, &a->user) < 0) + die("ptrace(PTRACE_SETREGS): %m"); +} + +#endif + /*** Syscall checks ***/ static void -valid_filename(unsigned long addr) +valid_filename(arg_t addr) { char namebuf[4096], *p, *end; static int mem_fd; @@ -659,9 +785,9 @@ valid_filename(unsigned long addr) // Check syscall. If invalid, return -1, otherwise return the action mask. static int -valid_syscall(struct user *u) +valid_syscall(struct syscall_args *a) { - unsigned int sys = u->regs.orig_eax; + unsigned int sys = a->sys; unsigned int act = (sys < NUM_ACTIONS) ? syscall_action[sys] : A_DEFAULT; if (act & A_LIBERAL) @@ -677,7 +803,7 @@ valid_syscall(struct user *u) case A_NO: return -1; case A_FILENAME: - valid_filename(u->regs.ebx); + valid_filename(a->arg1); return act; default: ; } @@ -685,17 +811,17 @@ valid_syscall(struct user *u) switch (sys) { case __NR_kill: - if (u->regs.ebx == box_pid) + if (a->arg1 == (arg_t) box_pid) { - meta_printf("exitsig:%d\n", (int)u->regs.ecx); - err("SG: Committed suicide by signal %d", (int)u->regs.ecx); + meta_printf("exitsig:%d\n", (int) a->arg2); + err("SG: Committed suicide by signal %d", (int) a->arg2); } return -1; case __NR_tgkill: - if (u->regs.ebx == box_pid && u->regs.ecx == box_pid) + if (a->arg1 == (arg_t) box_pid && a->arg2 == (arg_t) box_pid) { - meta_printf("exitsig:%d\n", (int)u->regs.edx); - err("SG: Committed suicide by signal %d", (int)u->regs.edx); + meta_printf("exitsig:%d\n", (int) a->arg3); + err("SG: Committed suicide by signal %d", (int) a->arg3); } return -1; default: @@ -924,23 +1050,24 @@ boxkeeper(void) { if (verbose > 2) msg("[ptrace status %08x] ", stat); - struct user u; - static unsigned int sys_tick, last_sys, last_act; - if (ptrace(PTRACE_GETREGS, box_pid, NULL, &u) < 0) - die("ptrace(PTRACE_GETREGS): %m"); - unsigned int sys = u.regs.orig_eax; + struct syscall_args a; + static unsigned int sys_tick, last_act; + static arg_t last_sys; if (++sys_tick & 1) /* Syscall entry */ { char namebuf[32]; int act; - msg(">> Syscall %-12s (%08lx,%08lx,%08lx) ", syscall_name(sys, namebuf), u.regs.ebx, u.regs.ecx, u.regs.edx); + + get_syscall_args(&a, 0); + arg_t sys = a.sys; + msg(">> Syscall %-12s (%08jx,%08jx,%08jx) ", syscall_name(sys, namebuf), (intmax_t) a.arg1, (intmax_t) a.arg2, (intmax_t) a.arg3); if (!exec_seen) { msg("[master] "); if (sys == __NR_execve) exec_seen = 1; } - else if ((act = valid_syscall(&u)) >= 0) + else if ((act = valid_syscall(&a)) >= 0) { last_act = act; syscall_count++; @@ -954,16 +1081,15 @@ boxkeeper(void) * so we have to change it to something harmless (e.g., an undefined * syscall) and make the program continue. */ - u.regs.orig_eax = 0xffffffff; - if (ptrace(PTRACE_SETREGS, box_pid, NULL, &u) < 0) - die("ptrace(PTRACE_SETREGS): %m"); + set_syscall_nr(&a, ~(arg_t)0); err("FO: Forbidden syscall %s", syscall_name(sys, namebuf)); } last_sys = sys; } else /* Syscall return */ { - if (sys == 0xffffffff) + get_syscall_args(&a, 1); + if (a.sys == ~(arg_t)0) { /* Some syscalls (sigreturn et al.) do not return a value */ if (!(last_act & A_NO_RETVAL)) @@ -971,13 +1097,13 @@ boxkeeper(void) } else { - if (sys != last_sys) + if (a.sys != last_sys) err("XX: Mismatched syscall entry/exit"); } if (last_act & A_NO_RETVAL) msg("= ?\n"); else - msg("= %ld\n", u.regs.eax); + msg("= %jd\n", (intmax_t) a.result); } ptrace(PTRACE_SYSCALL, box_pid, 0, 0); }