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Diffstat (limited to 'src/common/sandbox.c')
| -rw-r--r-- | src/common/sandbox.c | 1758 |
1 files changed, 1758 insertions, 0 deletions
diff --git a/src/common/sandbox.c b/src/common/sandbox.c new file mode 100644 index 000000000..4721b8dfc --- /dev/null +++ b/src/common/sandbox.c @@ -0,0 +1,1758 @@ +/* Copyright (c) 2001 Matej Pfajfar. + * Copyright (c) 2001-2004, Roger Dingledine. + * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson. + * Copyright (c) 2007-2013, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +/** + * \file sandbox.c + * \brief Code to enable sandboxing. + **/ + +#include "orconfig.h" + +#ifndef _LARGEFILE64_SOURCE +/** + * Temporarily required for O_LARGEFILE flag. Needs to be removed + * with the libevent fix. + */ +#define _LARGEFILE64_SOURCE +#endif + +/** Malloc mprotect limit in bytes. */ +#define MALLOC_MP_LIM 1048576 + +#include <stdio.h> +#include <string.h> +#include <stdlib.h> + +#include "sandbox.h" +#include "container.h" +#include "torlog.h" +#include "torint.h" +#include "util.h" +#include "tor_queue.h" + +#define DEBUGGING_CLOSE + +#if defined(USE_LIBSECCOMP) + +#define _GNU_SOURCE + +#include <sys/mman.h> +#include <sys/syscall.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <sys/epoll.h> +#include <sys/prctl.h> +#include <linux/futex.h> +#include <bits/signum.h> + +#include <stdarg.h> +#include <seccomp.h> +#include <signal.h> +#include <unistd.h> +#include <fcntl.h> +#include <time.h> +#include <poll.h> + +#if defined(HAVE_EXECINFO_H) && defined(HAVE_BACKTRACE) && \ + defined(HAVE_BACKTRACE_SYMBOLS_FD) && defined(HAVE_SIGACTION) +#define USE_BACKTRACE +#define EXPOSE_CLEAN_BACKTRACE +#include "backtrace.h" +#endif + +#ifdef USE_BACKTRACE +#include <execinfo.h> +#endif + +/** + * Linux 32 bit definitions + */ +#if defined(__i386__) + +#define REG_SYSCALL REG_EAX +#define M_SYSCALL gregs[REG_SYSCALL] + +/** + * Linux 64 bit definitions + */ +#elif defined(__x86_64__) + +#define REG_SYSCALL REG_RAX +#define M_SYSCALL gregs[REG_SYSCALL] + +#elif defined(__arm__) + +#define M_SYSCALL arm_r7 + +#endif + +/**Determines if at least one sandbox is active.*/ +static int sandbox_active = 0; +/** Holds the parameter list configuration for the sandbox.*/ +static sandbox_cfg_t *filter_dynamic = NULL; +/** Holds a list of pre-recorded results from getaddrinfo().*/ +static sb_addr_info_t *sb_addr_info = NULL; + +#undef SCMP_CMP +#define SCMP_CMP(a,b,c) ((struct scmp_arg_cmp){(a),(b),(c),0}) +#define SCMP_CMP4(a,b,c,d) ((struct scmp_arg_cmp){(a),(b),(c),(d)}) +/* We use a wrapper here because these masked comparisons seem to be pretty + * verbose. Also, it's important to cast to scmp_datum_t before negating the + * mask, since otherwise the negation might get applied to a 32 bit value, and + * the high bits of the value might get masked out improperly. */ +#define SCMP_CMP_MASKED(a,b,c) \ + SCMP_CMP4((a), SCMP_CMP_MASKED_EQ, ~(scmp_datum_t)(b), (c)) + +/** Variable used for storing all syscall numbers that will be allowed with the + * stage 1 general Tor sandbox. + */ +static int filter_nopar_gen[] = { + SCMP_SYS(access), + SCMP_SYS(brk), + SCMP_SYS(clock_gettime), + SCMP_SYS(close), + SCMP_SYS(clone), + SCMP_SYS(epoll_create), + SCMP_SYS(epoll_wait), + SCMP_SYS(fcntl), + SCMP_SYS(fstat), +#ifdef __NR_fstat64 + SCMP_SYS(fstat64), +#endif + SCMP_SYS(getdents64), + SCMP_SYS(getegid), +#ifdef __NR_getegid32 + SCMP_SYS(getegid32), +#endif + SCMP_SYS(geteuid), +#ifdef __NR_geteuid32 + SCMP_SYS(geteuid32), +#endif + SCMP_SYS(getgid), +#ifdef __NR_getgid32 + SCMP_SYS(getgid32), +#endif +#ifdef __NR_getrlimit + SCMP_SYS(getrlimit), +#endif + SCMP_SYS(gettimeofday), + SCMP_SYS(gettid), + SCMP_SYS(getuid), +#ifdef __NR_getuid32 + SCMP_SYS(getuid32), +#endif + SCMP_SYS(lseek), +#ifdef __NR__llseek + SCMP_SYS(_llseek), +#endif + SCMP_SYS(mkdir), + SCMP_SYS(mlockall), +#ifdef __NR_mmap + /* XXXX restrict this in the same ways as mmap2 */ + SCMP_SYS(mmap), +#endif + SCMP_SYS(munmap), + SCMP_SYS(read), + SCMP_SYS(rt_sigreturn), + SCMP_SYS(sched_getaffinity), + SCMP_SYS(set_robust_list), +#ifdef __NR_sigreturn + SCMP_SYS(sigreturn), +#endif + SCMP_SYS(stat), + SCMP_SYS(uname), + SCMP_SYS(write), + SCMP_SYS(writev), + SCMP_SYS(exit_group), + SCMP_SYS(exit), + + SCMP_SYS(madvise), +#ifdef __NR_stat64 + // getaddrinfo uses this.. + SCMP_SYS(stat64), +#endif + + /* + * These socket syscalls are not required on x86_64 and not supported with + * some libseccomp versions (eg: 1.0.1) + */ +#if defined(__i386) + SCMP_SYS(recv), + SCMP_SYS(send), +#endif + + // socket syscalls + SCMP_SYS(bind), + SCMP_SYS(listen), + SCMP_SYS(connect), + SCMP_SYS(getsockname), + SCMP_SYS(recvmsg), + SCMP_SYS(recvfrom), + SCMP_SYS(sendto), + SCMP_SYS(unlink) +}; + +/* These macros help avoid the error where the number of filters we add on a + * single rule don't match the arg_cnt param. */ +#define seccomp_rule_add_0(ctx,act,call) \ + seccomp_rule_add((ctx),(act),(call),0) +#define seccomp_rule_add_1(ctx,act,call,f1) \ + seccomp_rule_add((ctx),(act),(call),1,(f1)) +#define seccomp_rule_add_2(ctx,act,call,f1,f2) \ + seccomp_rule_add((ctx),(act),(call),2,(f1),(f2)) +#define seccomp_rule_add_3(ctx,act,call,f1,f2,f3) \ + seccomp_rule_add((ctx),(act),(call),3,(f1),(f2),(f3)) +#define seccomp_rule_add_4(ctx,act,call,f1,f2,f3,f4) \ + seccomp_rule_add((ctx),(act),(call),4,(f1),(f2),(f3),(f4)) + +/** + * Function responsible for setting up the rt_sigaction syscall for + * the seccomp filter sandbox. + */ +static int +sb_rt_sigaction(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + unsigned i; + int rc; + int param[] = { SIGINT, SIGTERM, SIGPIPE, SIGUSR1, SIGUSR2, SIGHUP, SIGCHLD, +#ifdef SIGXFSZ + SIGXFSZ +#endif + }; + (void) filter; + + for (i = 0; i < ARRAY_LENGTH(param); i++) { + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(rt_sigaction), + SCMP_CMP(0, SCMP_CMP_EQ, param[i])); + if (rc) + break; + } + + return rc; +} + +#if 0 +/** + * Function responsible for setting up the execve syscall for + * the seccomp filter sandbox. + */ +static int +sb_execve(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + int rc; + sandbox_cfg_t *elem = NULL; + + // for each dynamic parameter filters + for (elem = filter; elem != NULL; elem = elem->next) { + smp_param_t *param = elem->param; + + if (param != NULL && param->prot == 1 && param->syscall + == SCMP_SYS(execve)) { + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(execve), + SCMP_CMP(0, SCMP_CMP_EQ, param->value)); + if (rc != 0) { + log_err(LD_BUG,"(Sandbox) failed to add execve syscall, received " + "libseccomp error %d", rc); + return rc; + } + } + } + + return 0; +} +#endif + +/** + * Function responsible for setting up the time syscall for + * the seccomp filter sandbox. + */ +static int +sb_time(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + (void) filter; +#ifdef __NR_time + return seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(time), + SCMP_CMP(0, SCMP_CMP_EQ, 0)); +#else + return 0; +#endif +} + +/** + * Function responsible for setting up the accept4 syscall for + * the seccomp filter sandbox. + */ +static int +sb_accept4(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + int rc = 0; + (void)filter; + +#ifdef __i386__ + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(socketcall), + SCMP_CMP(0, SCMP_CMP_EQ, 18)); + if (rc) { + return rc; + } +#endif + + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(accept4), + SCMP_CMP_MASKED(3, SOCK_CLOEXEC|SOCK_NONBLOCK, 0)); + if (rc) { + return rc; + } + + return 0; +} + +#ifdef __NR_mmap2 +/** + * Function responsible for setting up the mmap2 syscall for + * the seccomp filter sandbox. + */ +static int +sb_mmap2(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + int rc = 0; + (void)filter; + + rc = seccomp_rule_add_2(ctx, SCMP_ACT_ALLOW, SCMP_SYS(mmap2), + SCMP_CMP(2, SCMP_CMP_EQ, PROT_READ), + SCMP_CMP(3, SCMP_CMP_EQ, MAP_PRIVATE)); + if (rc) { + return rc; + } + + rc = seccomp_rule_add_2(ctx, SCMP_ACT_ALLOW, SCMP_SYS(mmap2), + SCMP_CMP(2, SCMP_CMP_EQ, PROT_NONE), + SCMP_CMP(3, SCMP_CMP_EQ, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE)); + if (rc) { + return rc; + } + + rc = seccomp_rule_add_2(ctx, SCMP_ACT_ALLOW, SCMP_SYS(mmap2), + SCMP_CMP(2, SCMP_CMP_EQ, PROT_READ|PROT_WRITE), + SCMP_CMP(3, SCMP_CMP_EQ, MAP_PRIVATE|MAP_ANONYMOUS)); + if (rc) { + return rc; + } + + rc = seccomp_rule_add_2(ctx, SCMP_ACT_ALLOW, SCMP_SYS(mmap2), + SCMP_CMP(2, SCMP_CMP_EQ, PROT_READ|PROT_WRITE), + SCMP_CMP(3, SCMP_CMP_EQ,MAP_PRIVATE|MAP_ANONYMOUS|MAP_STACK)); + if (rc) { + return rc; + } + + rc = seccomp_rule_add_2(ctx, SCMP_ACT_ALLOW, SCMP_SYS(mmap2), + SCMP_CMP(2, SCMP_CMP_EQ, PROT_READ|PROT_WRITE), + SCMP_CMP(3, SCMP_CMP_EQ, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE)); + if (rc) { + return rc; + } + + rc = seccomp_rule_add_2(ctx, SCMP_ACT_ALLOW, SCMP_SYS(mmap2), + SCMP_CMP(2, SCMP_CMP_EQ, PROT_READ|PROT_WRITE), + SCMP_CMP(3, SCMP_CMP_EQ, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS)); + if (rc) { + return rc; + } + + rc = seccomp_rule_add_2(ctx, SCMP_ACT_ALLOW, SCMP_SYS(mmap2), + SCMP_CMP(2, SCMP_CMP_EQ, PROT_READ|PROT_EXEC), + SCMP_CMP(3, SCMP_CMP_EQ, MAP_PRIVATE|MAP_DENYWRITE)); + if (rc) { + return rc; + } + + return 0; +} +#endif + +/** + * Function responsible for setting up the open syscall for + * the seccomp filter sandbox. + */ +static int +sb_open(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + int rc; + sandbox_cfg_t *elem = NULL; + + // for each dynamic parameter filters + for (elem = filter; elem != NULL; elem = elem->next) { + smp_param_t *param = elem->param; + + if (param != NULL && param->prot == 1 && param->syscall + == SCMP_SYS(open)) { + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(open), + SCMP_CMP(0, SCMP_CMP_EQ, param->value)); + if (rc != 0) { + log_err(LD_BUG,"(Sandbox) failed to add open syscall, received " + "libseccomp error %d", rc); + return rc; + } + } + } + + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ERRNO(EACCES), SCMP_SYS(open), + SCMP_CMP_MASKED(1, O_CLOEXEC|O_NONBLOCK|O_NOCTTY, O_RDONLY)); + if (rc != 0) { + log_err(LD_BUG,"(Sandbox) failed to add open syscall, received libseccomp " + "error %d", rc); + return rc; + } + + return 0; +} + +static int +sb__sysctl(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + int rc; + (void) filter; + (void) ctx; + + rc = seccomp_rule_add_0(ctx, SCMP_ACT_ERRNO(EPERM), SCMP_SYS(_sysctl)); + if (rc != 0) { + log_err(LD_BUG,"(Sandbox) failed to add _sysctl syscall, " + "received libseccomp error %d", rc); + return rc; + } + + return 0; +} + +/** + * Function responsible for setting up the rename syscall for + * the seccomp filter sandbox. + */ +static int +sb_rename(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + int rc; + sandbox_cfg_t *elem = NULL; + + // for each dynamic parameter filters + for (elem = filter; elem != NULL; elem = elem->next) { + smp_param_t *param = elem->param; + + if (param != NULL && param->prot == 1 && + param->syscall == SCMP_SYS(rename)) { + + rc = seccomp_rule_add_2(ctx, SCMP_ACT_ALLOW, SCMP_SYS(rename), + SCMP_CMP(0, SCMP_CMP_EQ, param->value), + SCMP_CMP(1, SCMP_CMP_EQ, param->value2)); + if (rc != 0) { + log_err(LD_BUG,"(Sandbox) failed to add rename syscall, received " + "libseccomp error %d", rc); + return rc; + } + } + } + + return 0; +} + +/** + * Function responsible for setting up the openat syscall for + * the seccomp filter sandbox. + */ +static int +sb_openat(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + int rc; + sandbox_cfg_t *elem = NULL; + + // for each dynamic parameter filters + for (elem = filter; elem != NULL; elem = elem->next) { + smp_param_t *param = elem->param; + + if (param != NULL && param->prot == 1 && param->syscall + == SCMP_SYS(openat)) { + rc = seccomp_rule_add_3(ctx, SCMP_ACT_ALLOW, SCMP_SYS(openat), + SCMP_CMP(0, SCMP_CMP_EQ, AT_FDCWD), + SCMP_CMP(1, SCMP_CMP_EQ, param->value), + SCMP_CMP(2, SCMP_CMP_EQ, O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY| + O_CLOEXEC)); + if (rc != 0) { + log_err(LD_BUG,"(Sandbox) failed to add openat syscall, received " + "libseccomp error %d", rc); + return rc; + } + } + } + + return 0; +} + +/** + * Function responsible for setting up the socket syscall for + * the seccomp filter sandbox. + */ +static int +sb_socket(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + int rc = 0; + int i; + (void) filter; + +#ifdef __i386__ + rc = seccomp_rule_add_0(ctx, SCMP_ACT_ALLOW, SCMP_SYS(socket)); + if (rc) + return rc; +#endif + + rc = seccomp_rule_add_2(ctx, SCMP_ACT_ALLOW, SCMP_SYS(socket), + SCMP_CMP(0, SCMP_CMP_EQ, PF_FILE), + SCMP_CMP_MASKED(1, SOCK_CLOEXEC|SOCK_NONBLOCK, SOCK_STREAM)); + if (rc) + return rc; + + for (i = 0; i < 2; ++i) { + const int pf = i ? PF_INET : PF_INET6; + + rc = seccomp_rule_add_3(ctx, SCMP_ACT_ALLOW, SCMP_SYS(socket), + SCMP_CMP(0, SCMP_CMP_EQ, pf), + SCMP_CMP_MASKED(1, SOCK_CLOEXEC|SOCK_NONBLOCK, SOCK_STREAM), + SCMP_CMP(2, SCMP_CMP_EQ, IPPROTO_TCP)); + if (rc) + return rc; + + rc = seccomp_rule_add_3(ctx, SCMP_ACT_ALLOW, SCMP_SYS(socket), + SCMP_CMP(0, SCMP_CMP_EQ, pf), + SCMP_CMP_MASKED(1, SOCK_CLOEXEC|SOCK_NONBLOCK, SOCK_DGRAM), + SCMP_CMP(2, SCMP_CMP_EQ, IPPROTO_IP)); + if (rc) + return rc; + } + + rc = seccomp_rule_add_3(ctx, SCMP_ACT_ALLOW, SCMP_SYS(socket), + SCMP_CMP(0, SCMP_CMP_EQ, PF_NETLINK), + SCMP_CMP(1, SCMP_CMP_EQ, SOCK_RAW), + SCMP_CMP(2, SCMP_CMP_EQ, 0)); + if (rc) + return rc; + + return 0; +} + +/** + * Function responsible for setting up the socketpair syscall for + * the seccomp filter sandbox. + */ +static int +sb_socketpair(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + int rc = 0; + (void) filter; + +#ifdef __i386__ + rc = seccomp_rule_add_0(ctx, SCMP_ACT_ALLOW, SCMP_SYS(socketpair)); + if (rc) + return rc; +#endif + + rc = seccomp_rule_add_2(ctx, SCMP_ACT_ALLOW, SCMP_SYS(socketpair), + SCMP_CMP(0, SCMP_CMP_EQ, PF_FILE), + SCMP_CMP(1, SCMP_CMP_EQ, SOCK_STREAM|SOCK_CLOEXEC)); + if (rc) + return rc; + + return 0; +} + +/** + * Function responsible for setting up the setsockopt syscall for + * the seccomp filter sandbox. + */ +static int +sb_setsockopt(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + int rc = 0; + (void) filter; + +#ifdef __i386__ + rc = seccomp_rule_add_0(ctx, SCMP_ACT_ALLOW, SCMP_SYS(setsockopt)); + if (rc) + return rc; +#endif + + rc = seccomp_rule_add_2(ctx, SCMP_ACT_ALLOW, SCMP_SYS(setsockopt), + SCMP_CMP(1, SCMP_CMP_EQ, SOL_SOCKET), + SCMP_CMP(2, SCMP_CMP_EQ, SO_REUSEADDR)); + if (rc) + return rc; + + rc = seccomp_rule_add_2(ctx, SCMP_ACT_ALLOW, SCMP_SYS(setsockopt), + SCMP_CMP(1, SCMP_CMP_EQ, SOL_SOCKET), + SCMP_CMP(2, SCMP_CMP_EQ, SO_SNDBUF)); + if (rc) + return rc; + + rc = seccomp_rule_add_2(ctx, SCMP_ACT_ALLOW, SCMP_SYS(setsockopt), + SCMP_CMP(1, SCMP_CMP_EQ, SOL_SOCKET), + SCMP_CMP(2, SCMP_CMP_EQ, SO_RCVBUF)); + if (rc) + return rc; + +#ifdef IP_TRANSPARENT + rc = seccomp_rule_add_2(ctx, SCMP_ACT_ALLOW, SCMP_SYS(setsockopt), + SCMP_CMP(1, SCMP_CMP_EQ, SOL_IP), + SCMP_CMP(2, SCMP_CMP_EQ, IP_TRANSPARENT)); + if (rc) + return rc; +#endif + + return 0; +} + +/** + * Function responsible for setting up the getsockopt syscall for + * the seccomp filter sandbox. + */ +static int +sb_getsockopt(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + int rc = 0; + (void) filter; + +#ifdef __i386__ + rc = seccomp_rule_add_0(ctx, SCMP_ACT_ALLOW, SCMP_SYS(getsockopt)); + if (rc) + return rc; +#endif + + rc = seccomp_rule_add_2(ctx, SCMP_ACT_ALLOW, SCMP_SYS(getsockopt), + SCMP_CMP(1, SCMP_CMP_EQ, SOL_SOCKET), + SCMP_CMP(2, SCMP_CMP_EQ, SO_ERROR)); + if (rc) + return rc; + + return 0; +} + +#ifdef __NR_fcntl64 +/** + * Function responsible for setting up the fcntl64 syscall for + * the seccomp filter sandbox. + */ +static int +sb_fcntl64(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + int rc = 0; + (void) filter; + + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(fcntl64), + SCMP_CMP(1, SCMP_CMP_EQ, F_GETFL)); + if (rc) + return rc; + + rc = seccomp_rule_add_2(ctx, SCMP_ACT_ALLOW, SCMP_SYS(fcntl64), + SCMP_CMP(1, SCMP_CMP_EQ, F_SETFL), + SCMP_CMP(2, SCMP_CMP_EQ, O_RDWR|O_NONBLOCK)); + if (rc) + return rc; + + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(fcntl64), + SCMP_CMP(1, SCMP_CMP_EQ, F_GETFD)); + if (rc) + return rc; + + rc = seccomp_rule_add_2(ctx, SCMP_ACT_ALLOW, SCMP_SYS(fcntl64), + SCMP_CMP(1, SCMP_CMP_EQ, F_SETFD), + SCMP_CMP(2, SCMP_CMP_EQ, FD_CLOEXEC)); + if (rc) + return rc; + + return 0; +} +#endif + +/** + * Function responsible for setting up the epoll_ctl syscall for + * the seccomp filter sandbox. + * + * Note: basically allows everything but will keep for now.. + */ +static int +sb_epoll_ctl(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + int rc = 0; + (void) filter; + + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(epoll_ctl), + SCMP_CMP(1, SCMP_CMP_EQ, EPOLL_CTL_ADD)); + if (rc) + return rc; + + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(epoll_ctl), + SCMP_CMP(1, SCMP_CMP_EQ, EPOLL_CTL_MOD)); + if (rc) + return rc; + + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(epoll_ctl), + SCMP_CMP(1, SCMP_CMP_EQ, EPOLL_CTL_DEL)); + if (rc) + return rc; + + return 0; +} + +/** + * Function responsible for setting up the fcntl64 syscall for + * the seccomp filter sandbox. + * + * NOTE: if multiple filters need to be added, the PR_SECCOMP parameter needs + * to be whitelisted in this function. + */ +static int +sb_prctl(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + int rc = 0; + (void) filter; + + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(prctl), + SCMP_CMP(0, SCMP_CMP_EQ, PR_SET_DUMPABLE)); + if (rc) + return rc; + + return 0; +} + +/** + * Function responsible for setting up the fcntl64 syscall for + * the seccomp filter sandbox. + * + * NOTE: does not NEED to be here.. currently only occurs before filter; will + * keep just in case for the future. + */ +static int +sb_mprotect(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + int rc = 0; + (void) filter; + + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(mprotect), + SCMP_CMP(2, SCMP_CMP_EQ, PROT_READ)); + if (rc) + return rc; + + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(mprotect), + SCMP_CMP(2, SCMP_CMP_EQ, PROT_NONE)); + if (rc) + return rc; + + return 0; +} + +/** + * Function responsible for setting up the rt_sigprocmask syscall for + * the seccomp filter sandbox. + */ +static int +sb_rt_sigprocmask(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + int rc = 0; + (void) filter; + + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(rt_sigprocmask), + SCMP_CMP(0, SCMP_CMP_EQ, SIG_UNBLOCK)); + if (rc) + return rc; + + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(rt_sigprocmask), + SCMP_CMP(0, SCMP_CMP_EQ, SIG_SETMASK)); + if (rc) + return rc; + + return 0; +} + +/** + * Function responsible for setting up the flock syscall for + * the seccomp filter sandbox. + * + * NOTE: does not need to be here, occurs before filter is applied. + */ +static int +sb_flock(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + int rc = 0; + (void) filter; + + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(flock), + SCMP_CMP(1, SCMP_CMP_EQ, LOCK_EX|LOCK_NB)); + if (rc) + return rc; + + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(flock), + SCMP_CMP(1, SCMP_CMP_EQ, LOCK_UN)); + if (rc) + return rc; + + return 0; +} + +/** + * Function responsible for setting up the futex syscall for + * the seccomp filter sandbox. + */ +static int +sb_futex(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + int rc = 0; + (void) filter; + + // can remove + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(futex), + SCMP_CMP(1, SCMP_CMP_EQ, + FUTEX_WAIT_BITSET_PRIVATE|FUTEX_CLOCK_REALTIME)); + if (rc) + return rc; + + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(futex), + SCMP_CMP(1, SCMP_CMP_EQ, FUTEX_WAKE_PRIVATE)); + if (rc) + return rc; + + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(futex), + SCMP_CMP(1, SCMP_CMP_EQ, FUTEX_WAIT_PRIVATE)); + if (rc) + return rc; + + return 0; +} + +/** + * Function responsible for setting up the mremap syscall for + * the seccomp filter sandbox. + * + * NOTE: so far only occurs before filter is applied. + */ +static int +sb_mremap(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + int rc = 0; + (void) filter; + + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(mremap), + SCMP_CMP(3, SCMP_CMP_EQ, MREMAP_MAYMOVE)); + if (rc) + return rc; + + return 0; +} + +/** + * Function responsible for setting up the poll syscall for + * the seccomp filter sandbox. + */ +static int +sb_poll(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + int rc = 0; + (void) filter; + + rc = seccomp_rule_add_2(ctx, SCMP_ACT_ALLOW, SCMP_SYS(poll), + SCMP_CMP(1, SCMP_CMP_EQ, 1), + SCMP_CMP(2, SCMP_CMP_EQ, 10)); + if (rc) + return rc; + + return 0; +} + +#ifdef __NR_stat64 +/** + * Function responsible for setting up the stat64 syscall for + * the seccomp filter sandbox. + */ +static int +sb_stat64(scmp_filter_ctx ctx, sandbox_cfg_t *filter) +{ + int rc = 0; + sandbox_cfg_t *elem = NULL; + + // for each dynamic parameter filters + for (elem = filter; elem != NULL; elem = elem->next) { + smp_param_t *param = elem->param; + + if (param != NULL && param->prot == 1 && (param->syscall == SCMP_SYS(open) + || param->syscall == SCMP_SYS(stat64))) { + rc = seccomp_rule_add_1(ctx, SCMP_ACT_ALLOW, SCMP_SYS(stat64), + SCMP_CMP(0, SCMP_CMP_EQ, param->value)); + if (rc != 0) { + log_err(LD_BUG,"(Sandbox) failed to add open syscall, received " + "libseccomp error %d", rc); + return rc; + } + } + } + + return 0; +} +#endif + +/** + * Array of function pointers responsible for filtering different syscalls at + * a parameter level. + */ +static sandbox_filter_func_t filter_func[] = { + sb_rt_sigaction, + sb_rt_sigprocmask, +#if 0 + sb_execve, +#endif + sb_time, + sb_accept4, +#ifdef __NR_mmap2 + sb_mmap2, +#endif + sb_open, + sb_openat, + sb__sysctl, + sb_rename, +#ifdef __NR_fcntl64 + sb_fcntl64, +#endif + sb_epoll_ctl, + sb_prctl, + sb_mprotect, + sb_flock, + sb_futex, + sb_mremap, + sb_poll, +#ifdef __NR_stat64 + sb_stat64, +#endif + + sb_socket, + sb_setsockopt, + sb_getsockopt, + sb_socketpair +}; + +const char * +sandbox_intern_string(const char *str) +{ + sandbox_cfg_t *elem; + + if (str == NULL) + return NULL; + + for (elem = filter_dynamic; elem != NULL; elem = elem->next) { + smp_param_t *param = elem->param; + + if (param->prot) { + if (!strcmp(str, (char*)(param->value))) { + return (char*)param->value; + } + if (param->value2 && !strcmp(str, (char*)param->value2)) { + return (char*)param->value2; + } + } + } + + if (sandbox_active) + log_warn(LD_BUG, "No interned sandbox parameter found for %s", str); + return str; +} + +/** DOCDOC */ +static int +prot_strings_helper(strmap_t *locations, + char **pr_mem_next_p, + size_t *pr_mem_left_p, + intptr_t *value_p) +{ + char *param_val; + size_t param_size; + void *location; + + if (*value_p == 0) + return 0; + + param_val = (char*) *value_p; + param_size = strlen(param_val) + 1; + location = strmap_get(locations, param_val); + + if (location) { + // We already interned this string. + tor_free(param_val); + *value_p = (intptr_t) location; + return 0; + } else if (*pr_mem_left_p >= param_size) { + // copy to protected + location = *pr_mem_next_p; + memcpy(location, param_val, param_size); + + // re-point el parameter to protected + tor_free(param_val); + *value_p = (intptr_t) location; + + strmap_set(locations, location, location); /* good real estate advice */ + + // move next available protected memory + *pr_mem_next_p += param_size; + *pr_mem_left_p -= param_size; + return 0; + } else { + log_err(LD_BUG,"(Sandbox) insufficient protected memory!"); + return -1; + } +} + +/** + * Protects all the strings in the sandbox's parameter list configuration. It + * works by calculating the total amount of memory required by the parameter + * list, allocating the memory using mmap, and protecting it from writes with + * mprotect(). + */ +static int +prot_strings(scmp_filter_ctx ctx, sandbox_cfg_t* cfg) +{ + int ret = 0; + size_t pr_mem_size = 0, pr_mem_left = 0; + char *pr_mem_next = NULL, *pr_mem_base; + sandbox_cfg_t *el = NULL; + strmap_t *locations = NULL; + + // get total number of bytes required to mmap. (Overestimate.) + for (el = cfg; el != NULL; el = el->next) { + pr_mem_size += strlen((char*) el->param->value) + 1; + if (el->param->value2) + pr_mem_size += strlen((char*) el->param->value2) + 1; + } + + // allocate protected memory with MALLOC_MP_LIM canary + pr_mem_base = (char*) mmap(NULL, MALLOC_MP_LIM + pr_mem_size, + PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0); + if (pr_mem_base == MAP_FAILED) { + log_err(LD_BUG,"(Sandbox) failed allocate protected memory! mmap: %s", + strerror(errno)); + ret = -1; + goto out; + } + + pr_mem_next = pr_mem_base + MALLOC_MP_LIM; + pr_mem_left = pr_mem_size; + + locations = strmap_new(); + + // change el value pointer to protected + for (el = cfg; el != NULL; el = el->next) { + if (prot_strings_helper(locations, &pr_mem_next, &pr_mem_left, + &el->param->value) < 0) { + ret = -2; + goto out; + } + if (prot_strings_helper(locations, &pr_mem_next, &pr_mem_left, + &el->param->value2) < 0) { + ret = -2; + goto out; + } + el->param->prot = 1; + } + + // protecting from writes + if (mprotect(pr_mem_base, MALLOC_MP_LIM + pr_mem_size, PROT_READ)) { + log_err(LD_BUG,"(Sandbox) failed to protect memory! mprotect: %s", + strerror(errno)); + ret = -3; + goto out; + } + + /* + * Setting sandbox restrictions so the string memory cannot be tampered with + */ + // no mremap of the protected base address + ret = seccomp_rule_add_1(ctx, SCMP_ACT_KILL, SCMP_SYS(mremap), + SCMP_CMP(0, SCMP_CMP_EQ, (intptr_t) pr_mem_base)); + if (ret) { + log_err(LD_BUG,"(Sandbox) mremap protected memory filter fail!"); + return ret; + } + + // no munmap of the protected base address + ret = seccomp_rule_add_1(ctx, SCMP_ACT_KILL, SCMP_SYS(munmap), + SCMP_CMP(0, SCMP_CMP_EQ, (intptr_t) pr_mem_base)); + if (ret) { + log_err(LD_BUG,"(Sandbox) munmap protected memory filter fail!"); + return ret; + } + + /* + * Allow mprotect with PROT_READ|PROT_WRITE because openssl uses it, but + * never over the memory region used by the protected strings. + * + * PROT_READ|PROT_WRITE was originally fully allowed in sb_mprotect(), but + * had to be removed due to limitation of libseccomp regarding intervals. + * + * There is a restriction on how much you can mprotect with R|W up to the + * size of the canary. + */ + ret = seccomp_rule_add_3(ctx, SCMP_ACT_ALLOW, SCMP_SYS(mprotect), + SCMP_CMP(0, SCMP_CMP_LT, (intptr_t) pr_mem_base), + SCMP_CMP(1, SCMP_CMP_LE, MALLOC_MP_LIM), + SCMP_CMP(2, SCMP_CMP_EQ, PROT_READ|PROT_WRITE)); + if (ret) { + log_err(LD_BUG,"(Sandbox) mprotect protected memory filter fail (LT)!"); + return ret; + } + + ret = seccomp_rule_add_3(ctx, SCMP_ACT_ALLOW, SCMP_SYS(mprotect), + SCMP_CMP(0, SCMP_CMP_GT, (intptr_t) pr_mem_base + pr_mem_size + + MALLOC_MP_LIM), + SCMP_CMP(1, SCMP_CMP_LE, MALLOC_MP_LIM), + SCMP_CMP(2, SCMP_CMP_EQ, PROT_READ|PROT_WRITE)); + if (ret) { + log_err(LD_BUG,"(Sandbox) mprotect protected memory filter fail (GT)!"); + return ret; + } + + out: + strmap_free(locations, NULL); + return ret; +} + +/** + * Auxiliary function used in order to allocate a sandbox_cfg_t element and set + * it's values according the the parameter list. All elements are initialised + * with the 'prot' field set to false, as the pointer is not protected at this + * point. + */ +static sandbox_cfg_t* +new_element2(int syscall, intptr_t value, intptr_t value2) +{ + smp_param_t *param = NULL; + + sandbox_cfg_t *elem = tor_malloc_zero(sizeof(sandbox_cfg_t)); + param = elem->param = tor_malloc_zero(sizeof(smp_param_t)); + + param->syscall = syscall; + param->value = value; + param->value2 = value2; + param->prot = 0; + + return elem; +} + +static sandbox_cfg_t* +new_element(int syscall, intptr_t value) +{ + return new_element2(syscall, value, 0); +} + +#ifdef __NR_stat64 +#define SCMP_stat SCMP_SYS(stat64) +#else +#define SCMP_stat SCMP_SYS(stat) +#endif + +int +sandbox_cfg_allow_stat_filename(sandbox_cfg_t **cfg, char *file) +{ + sandbox_cfg_t *elem = NULL; + + elem = new_element(SCMP_stat, (intptr_t)(void*) file); + if (!elem) { + log_err(LD_BUG,"(Sandbox) failed to register parameter!"); + return -1; + } + + elem->next = *cfg; + *cfg = elem; + + return 0; +} + +int +sandbox_cfg_allow_stat_filename_array(sandbox_cfg_t **cfg, ...) +{ + int rc = 0; + char *fn = NULL; + + va_list ap; + va_start(ap, cfg); + + while ((fn = va_arg(ap, char*)) != NULL) { + rc = sandbox_cfg_allow_stat_filename(cfg, fn); + if (rc) { + log_err(LD_BUG,"(Sandbox) sandbox_cfg_allow_stat_filename_array fail"); + goto end; + } + } + + end: + va_end(ap); + return 0; +} + +int +sandbox_cfg_allow_open_filename(sandbox_cfg_t **cfg, char *file) +{ + sandbox_cfg_t *elem = NULL; + + elem = new_element(SCMP_SYS(open), (intptr_t)(void *) file); + if (!elem) { + log_err(LD_BUG,"(Sandbox) failed to register parameter!"); + return -1; + } + + elem->next = *cfg; + *cfg = elem; + + return 0; +} + +int +sandbox_cfg_allow_rename(sandbox_cfg_t **cfg, char *file1, char *file2) +{ + sandbox_cfg_t *elem = NULL; + + elem = new_element2(SCMP_SYS(rename), + (intptr_t)(void *) file1, + (intptr_t)(void *) file2); + + if (!elem) { + log_err(LD_BUG,"(Sandbox) failed to register parameter!"); + return -1; + } + + elem->next = *cfg; + *cfg = elem; + + return 0; +} + +int +sandbox_cfg_allow_open_filename_array(sandbox_cfg_t **cfg, ...) +{ + int rc = 0; + char *fn = NULL; + + va_list ap; + va_start(ap, cfg); + + while ((fn = va_arg(ap, char*)) != NULL) { + rc = sandbox_cfg_allow_open_filename(cfg, fn); + if (rc) { + log_err(LD_BUG,"(Sandbox) sandbox_cfg_allow_open_filename_array fail"); + goto end; + } + } + + end: + va_end(ap); + return 0; +} + +int +sandbox_cfg_allow_openat_filename(sandbox_cfg_t **cfg, char *file) +{ + sandbox_cfg_t *elem = NULL; + + elem = new_element(SCMP_SYS(openat), (intptr_t)(void *) file); + if (!elem) { + log_err(LD_BUG,"(Sandbox) failed to register parameter!"); + return -1; + } + + elem->next = *cfg; + *cfg = elem; + + return 0; +} + +int +sandbox_cfg_allow_openat_filename_array(sandbox_cfg_t **cfg, ...) +{ + int rc = 0; + char *fn = NULL; + + va_list ap; + va_start(ap, cfg); + + while ((fn = va_arg(ap, char*)) != NULL) { + rc = sandbox_cfg_allow_openat_filename(cfg, fn); + if (rc) { + log_err(LD_BUG,"(Sandbox) sandbox_cfg_allow_openat_filename_array fail"); + goto end; + } + } + + end: + va_end(ap); + return 0; +} + +#if 0 +int +sandbox_cfg_allow_execve(sandbox_cfg_t **cfg, const char *com) +{ + sandbox_cfg_t *elem = NULL; + + elem = new_element(SCMP_SYS(execve), (intptr_t)(void *) com); + if (!elem) { + log_err(LD_BUG,"(Sandbox) failed to register parameter!"); + return -1; + } + + elem->next = *cfg; + *cfg = elem; + + return 0; +} + +int +sandbox_cfg_allow_execve_array(sandbox_cfg_t **cfg, ...) +{ + int rc = 0; + char *fn = NULL; + + va_list ap; + va_start(ap, cfg); + + while ((fn = va_arg(ap, char*)) != NULL) { + + rc = sandbox_cfg_allow_execve(cfg, fn); + if (rc) { + log_err(LD_BUG,"(Sandbox) sandbox_cfg_allow_execve_array failed"); + goto end; + } + } + + end: + va_end(ap); + return 0; +} +#endif + +int +sandbox_getaddrinfo(const char *name, const char *servname, + const struct addrinfo *hints, + struct addrinfo **res) +{ + sb_addr_info_t *el; + + if (servname != NULL) + return -1; + + *res = NULL; + + for (el = sb_addr_info; el; el = el->next) { + if (!strcmp(el->name, name)) { + *res = tor_malloc(sizeof(struct addrinfo)); + + memcpy(*res, el->info, sizeof(struct addrinfo)); + /* XXXX What if there are multiple items in the list? */ + return 0; + } + } + + if (!sandbox_active) { + if (getaddrinfo(name, NULL, hints, res)) { + log_err(LD_BUG,"(Sandbox) getaddrinfo failed!"); + return -1; + } + + return 0; + } + + // getting here means something went wrong + log_err(LD_BUG,"(Sandbox) failed to get address %s!", name); + if (*res) { + tor_free(*res); + res = NULL; + } + return -1; +} + +int +sandbox_add_addrinfo(const char* name) +{ + int ret; + struct addrinfo hints; + sb_addr_info_t *el = NULL; + + el = tor_malloc(sizeof(sb_addr_info_t)); + + memset(&hints, 0, sizeof(hints)); + hints.ai_family = AF_INET; + hints.ai_socktype = SOCK_STREAM; + + ret = getaddrinfo(name, NULL, &hints, &(el->info)); + if (ret) { + log_err(LD_BUG,"(Sandbox) failed to getaddrinfo"); + ret = -2; + tor_free(el); + goto out; + } + + el->name = tor_strdup(name); + el->next = sb_addr_info; + sb_addr_info = el; + + out: + return ret; +} + +/** + * Function responsible for going through the parameter syscall filters and + * call each function pointer in the list. + */ +static int +add_param_filter(scmp_filter_ctx ctx, sandbox_cfg_t* cfg) +{ + unsigned i; + int rc = 0; + + // function pointer + for (i = 0; i < ARRAY_LENGTH(filter_func); i++) { + if ((filter_func[i])(ctx, cfg)) { + log_err(LD_BUG,"(Sandbox) failed to add syscall %d, received libseccomp " + "error %d", i, rc); + return rc; + } + } + + return 0; +} + +/** + * Function responsible of loading the libseccomp syscall filters which do not + * have parameter filtering. + */ +static int +add_noparam_filter(scmp_filter_ctx ctx) +{ + unsigned i; + int rc = 0; + + // add general filters + for (i = 0; i < ARRAY_LENGTH(filter_nopar_gen); i++) { + rc = seccomp_rule_add_0(ctx, SCMP_ACT_ALLOW, filter_nopar_gen[i]); + if (rc != 0) { + log_err(LD_BUG,"(Sandbox) failed to add syscall index %d (NR=%d), " + "received libseccomp error %d", i, filter_nopar_gen[i], rc); + return rc; + } + } + + return 0; +} + +/** + * Function responsible for setting up and enabling a global syscall filter. + * The function is a prototype developed for stage 1 of sandboxing Tor. + * Returns 0 on success. + */ +static int +install_syscall_filter(sandbox_cfg_t* cfg) +{ + int rc = 0; + scmp_filter_ctx ctx; + + ctx = seccomp_init(SCMP_ACT_TRAP); + if (ctx == NULL) { + log_err(LD_BUG,"(Sandbox) failed to initialise libseccomp context"); + rc = -1; + goto end; + } + + // protectign sandbox parameter strings + if ((rc = prot_strings(ctx, cfg))) { + goto end; + } + + // add parameter filters + if ((rc = add_param_filter(ctx, cfg))) { + log_err(LD_BUG, "(Sandbox) failed to add param filters!"); + goto end; + } + + // adding filters with no parameters + if ((rc = add_noparam_filter(ctx))) { + log_err(LD_BUG, "(Sandbox) failed to add param filters!"); + goto end; + } + + // loading the seccomp2 filter + if ((rc = seccomp_load(ctx))) { + log_err(LD_BUG, "(Sandbox) failed to load: %d (%s)!", rc, + strerror(-rc)); + goto end; + } + + // marking the sandbox as active + sandbox_active = 1; + + end: + seccomp_release(ctx); + return (rc < 0 ? -rc : rc); +} + +#include "linux_syscalls.inc" +static const char * +get_syscall_name(int syscall_num) +{ + int i; + for (i = 0; SYSCALLS_BY_NUMBER[i].syscall_name; ++i) { + if (SYSCALLS_BY_NUMBER[i].syscall_num == syscall_num) + return SYSCALLS_BY_NUMBER[i].syscall_name; + } + + { + static char syscall_name_buf[64]; + format_dec_number_sigsafe(syscall_num, + syscall_name_buf, sizeof(syscall_name_buf)); + return syscall_name_buf; + } +} + +#ifdef USE_BACKTRACE +#define MAX_DEPTH 256 +static void *syscall_cb_buf[MAX_DEPTH]; +#endif + +/** + * Function called when a SIGSYS is caught by the application. It notifies the + * user that an error has occurred and either terminates or allows the + * application to continue execution, based on the DEBUGGING_CLOSE symbol. + */ +static void +sigsys_debugging(int nr, siginfo_t *info, void *void_context) +{ + ucontext_t *ctx = (ucontext_t *) (void_context); + const char *syscall_name; + int syscall; +#ifdef USE_BACKTRACE + int depth; + int n_fds, i; + const int *fds = NULL; +#endif + + (void) nr; + + if (info->si_code != SYS_SECCOMP) + return; + + if (!ctx) + return; + + syscall = (int) ctx->uc_mcontext.M_SYSCALL; + +#ifdef USE_BACKTRACE + depth = backtrace(syscall_cb_buf, MAX_DEPTH); + /* Clean up the top stack frame so we get the real function + * name for the most recently failing function. */ + clean_backtrace(syscall_cb_buf, depth, ctx); +#endif + + syscall_name = get_syscall_name(syscall); + + tor_log_err_sigsafe("(Sandbox) Caught a bad syscall attempt (syscall ", + syscall_name, + ")\n", + NULL); + +#ifdef USE_BACKTRACE + n_fds = tor_log_get_sigsafe_err_fds(&fds); + for (i=0; i < n_fds; ++i) + backtrace_symbols_fd(syscall_cb_buf, depth, fds[i]); +#endif + +#if defined(DEBUGGING_CLOSE) + _exit(1); +#endif // DEBUGGING_CLOSE +} + +/** + * Function that adds a handler for SIGSYS, which is the signal thrown + * when the application is issuing a syscall which is not allowed. The + * main purpose of this function is to help with debugging by identifying + * filtered syscalls. + */ +static int +install_sigsys_debugging(void) +{ + struct sigaction act; + sigset_t mask; + + memset(&act, 0, sizeof(act)); + sigemptyset(&mask); + sigaddset(&mask, SIGSYS); + + act.sa_sigaction = &sigsys_debugging; + act.sa_flags = SA_SIGINFO; + if (sigaction(SIGSYS, &act, NULL) < 0) { + log_err(LD_BUG,"(Sandbox) Failed to register SIGSYS signal handler"); + return -1; + } + + if (sigprocmask(SIG_UNBLOCK, &mask, NULL)) { + log_err(LD_BUG,"(Sandbox) Failed call to sigprocmask()"); + return -2; + } + + return 0; +} + +/** + * Function responsible of registering the sandbox_cfg_t list of parameter + * syscall filters to the existing parameter list. This is used for incipient + * multiple-sandbox support. + */ +static int +register_cfg(sandbox_cfg_t* cfg) +{ + sandbox_cfg_t *elem = NULL; + + if (filter_dynamic == NULL) { + filter_dynamic = cfg; + return 0; + } + + for (elem = filter_dynamic; elem->next != NULL; elem = elem->next) + ; + + elem->next = cfg; + + return 0; +} + +#endif // USE_LIBSECCOMP + +#ifdef USE_LIBSECCOMP +/** + * Initialises the syscall sandbox filter for any linux architecture, taking + * into account various available features for different linux flavours. + */ +static int +initialise_libseccomp_sandbox(sandbox_cfg_t* cfg) +{ + if (install_sigsys_debugging()) + return -1; + + if (install_syscall_filter(cfg)) + return -2; + + if (register_cfg(cfg)) + return -3; + + return 0; +} + +int +sandbox_is_active(void) +{ + return sandbox_active != 0; +} +#endif // USE_LIBSECCOMP + +sandbox_cfg_t* +sandbox_cfg_new(void) +{ + return NULL; +} + +int +sandbox_init(sandbox_cfg_t *cfg) +{ +#if defined(USE_LIBSECCOMP) + return initialise_libseccomp_sandbox(cfg); + +#elif defined(__linux__) + (void)cfg; + log_warn(LD_GENERAL, + "This version of Tor was built without support for sandboxing. To " + "build with support for sandboxing on Linux, you must have " + "libseccomp and its necessary header files (e.g. seccomp.h)."); + return 0; + +#else + (void)cfg; + log_warn(LD_GENERAL, + "Currently, sandboxing is only implemented on Linux. The feature " + "is disabled on your platform."); + return 0; +#endif +} + +#ifndef USE_LIBSECCOMP +int +sandbox_cfg_allow_open_filename(sandbox_cfg_t **cfg, char *file) +{ + (void)cfg; (void)file; + return 0; +} + +int +sandbox_cfg_allow_open_filename_array(sandbox_cfg_t **cfg, ...) +{ + (void)cfg; + return 0; +} + +int +sandbox_cfg_allow_openat_filename(sandbox_cfg_t **cfg, char *file) +{ + (void)cfg; (void)file; + return 0; +} + +int +sandbox_cfg_allow_openat_filename_array(sandbox_cfg_t **cfg, ...) +{ + (void)cfg; + return 0; +} + +#if 0 +int +sandbox_cfg_allow_execve(sandbox_cfg_t **cfg, const char *com) +{ + (void)cfg; (void)com; + return 0; +} + +int +sandbox_cfg_allow_execve_array(sandbox_cfg_t **cfg, ...) +{ + (void)cfg; + return 0; +} +#endif + +int +sandbox_cfg_allow_stat_filename(sandbox_cfg_t **cfg, char *file) +{ + (void)cfg; (void)file; + return 0; +} + +int +sandbox_cfg_allow_stat_filename_array(sandbox_cfg_t **cfg, ...) +{ + (void)cfg; + return 0; +} + +int +sandbox_cfg_allow_rename(sandbox_cfg_t **cfg, char *file1, char *file2) +{ + (void)cfg; (void)file1; (void)file2; + return 0; +} + +int +sandbox_is_active(void) +{ + return 0; +} +#endif + |