mirror of
https://github.com/omar-polo/gmid.git
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before we matched ppc64le as ppc64 (which is big ending I presume), so the seccomp filter would always kill gmid #4 related
551 lines
12 KiB
C
551 lines
12 KiB
C
/*
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* Copyright (c) 2021 Omar Polo <op@omarpolo.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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#include "gmid.h"
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#if DISABLE_SANDBOX
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#warning "Sandbox disabled! Please report issues upstream instead of disabling the sandbox."
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void
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sandbox_server_process(void)
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{
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return;
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}
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void
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sandbox_executor_process(void)
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{
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log_notice(NULL, "Sandbox disabled! "
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"Please report issues upstream instead of disabling the sandbox.");
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}
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void
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sandbox_logger_process(void)
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{
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return;
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}
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#elif defined(__FreeBSD__)
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#include <sys/capsicum.h>
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void
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sandbox_server_process(void)
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{
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if (cap_enter() == -1)
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fatal("cap_enter");
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}
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void
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sandbox_executor_process(void)
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{
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/* We cannot capsicum the executor process because it needs
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* to fork(2)+execve(2) cgi scripts */
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return;
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}
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void
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sandbox_logger_process(void)
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{
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if (cap_enter() == -1)
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fatal("cap_enter");
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}
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#elif defined(__linux__)
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#include <sys/prctl.h>
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#include <sys/syscall.h>
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#include <sys/syscall.h>
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#include <sys/types.h>
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#include <linux/audit.h>
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#include <linux/filter.h>
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#include <linux/seccomp.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stddef.h>
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#include <stdio.h>
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#include <string.h>
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/* uncomment to enable debugging. ONLY FOR DEVELOPMENT */
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/* #define SC_DEBUG */
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#ifdef SC_DEBUG
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# define SC_FAIL SECCOMP_RET_TRAP
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#else
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# define SC_FAIL SECCOMP_RET_KILL
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#endif
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#if (BYTE_ORDER == LITTLE_ENDIAN)
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# define SC_ARG_LO 0
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# define SC_ARG_HI sizeof(uint32_t)
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#elif (BYTE_ORDER == BIG_ENDIAN)
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# define SC_ARG_LO sizeof(uint32_t)
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# define SC_ARG_HI 0
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#else
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# error "Uknown endian"
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#endif
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/* make the filter more readable */
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#define SC_ALLOW(nr) \
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BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, __NR_##nr, 0, 1), \
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BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_ALLOW)
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/*
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* SC_ALLOW_ARG and the SECCOMP_AUDIT_ARCH below are courtesy of
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* https://roy.marples.name/git/dhcpcd/blob/HEAD:/src/privsep-linux.c
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*/
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#define SC_ALLOW_ARG(_nr, _arg, _val) \
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BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, (_nr), 0, 6), \
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BPF_STMT(BPF_LD + BPF_W + BPF_ABS, \
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offsetof(struct seccomp_data, args[(_arg)]) + SC_ARG_LO), \
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BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, \
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((_val) & 0xffffffff), 0, 3), \
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BPF_STMT(BPF_LD + BPF_W + BPF_ABS, \
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offsetof(struct seccomp_data, args[(_arg)]) + SC_ARG_HI), \
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BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, \
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(((uint32_t)((uint64_t)(_val) >> 32)) & 0xffffffff), 0, 1), \
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BPF_STMT(BPF_RET + BPF_K, SECCOMP_RET_ALLOW), \
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BPF_STMT(BPF_LD + BPF_W + BPF_ABS, \
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offsetof(struct seccomp_data, nr))
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/*
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* I personally find this quite nutty. Why can a system header not
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* define a default for this?
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*/
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#if defined(__i386__)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_I386
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#elif defined(__x86_64__)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_X86_64
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#elif defined(__arc__)
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# if defined(__A7__)
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# if (BYTE_ORDER == LITTLE_ENDIAN)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_ARCOMPACT
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# else
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_ARCOMPACTBE
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# endif
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# elif defined(__HS__)
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# if (BYTE_ORDER == LITTLE_ENDIAN)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_ARCV2
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# else
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_ARCV2BE
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# endif
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# else
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# error "Platform does not support seccomp filter yet"
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# endif
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#elif defined(__arm__)
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# ifndef EM_ARM
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# define EM_ARM 40
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# endif
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# if (BYTE_ORDER == LITTLE_ENDIAN)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_ARM
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# else
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_ARMEB
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# endif
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#elif defined(__aarch64__)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_AARCH64
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#elif defined(__alpha__)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_ALPHA
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#elif defined(__hppa__)
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# if defined(__LP64__)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_PARISC64
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# else
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_PARISC
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# endif
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#elif defined(__ia64__)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_IA64
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#elif defined(__microblaze__)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_MICROBLAZE
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#elif defined(__m68k__)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_M68K
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#elif defined(__mips__)
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# if defined(__MIPSEL__)
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# if defined(__LP64__)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_MIPSEL64
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# else
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_MIPSEL
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# endif
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# elif defined(__LP64__)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_MIPS64
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# else
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_MIPS
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# endif
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#elif defined(__nds32__)
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# if (BYTE_ORDER == LITTLE_ENDIAN)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_NDS32
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#else
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_NDS32BE
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#endif
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#elif defined(__nios2__)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_NIOS2
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#elif defined(__or1k__)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_OPENRISC
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#elif defined(__powerpc64__)
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# if (BYTE_ORDER == LITTLE_ENDIAN)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_PPC64LE
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# else
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_PPC64
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# endif
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#elif defined(__powerpc__)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_PPC
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#elif defined(__riscv)
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# if defined(__LP64__)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_RISCV64
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# else
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_RISCV32
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# endif
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#elif defined(__s390x__)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_S390X
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#elif defined(__s390__)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_S390
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#elif defined(__sh__)
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# if defined(__LP64__)
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# if (BYTE_ORDER == LITTLE_ENDIAN)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_SHEL64
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# else
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_SH64
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# endif
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# else
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# if (BYTE_ORDER == LITTLE_ENDIAN)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_SHEL
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# else
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_SH
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# endif
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# endif
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#elif defined(__sparc__)
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# if defined(__arch64__)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_SPARC64
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# else
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_SPARC
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# endif
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#elif defined(__xtensa__)
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# define SECCOMP_AUDIT_ARCH AUDIT_ARCH_XTENSA
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#else
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# error "Platform does not support seccomp filter yet"
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#endif
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static struct sock_filter filter[] = {
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/* load the *current* architecture */
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BPF_STMT(BPF_LD | BPF_W | BPF_ABS,
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(offsetof(struct seccomp_data, arch))),
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/* ensure it's the same that we've been compiled on */
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BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K,
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SECCOMP_AUDIT_ARCH, 1, 0),
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/* if not, kill the program */
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BPF_STMT(BPF_RET | BPF_K, SC_FAIL),
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/* load the syscall number */
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BPF_STMT(BPF_LD | BPF_W | BPF_ABS,
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(offsetof(struct seccomp_data, nr))),
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#ifdef __NR_accept
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SC_ALLOW(accept),
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#endif
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#ifdef __NR_accept4
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SC_ALLOW(accept4),
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#endif
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#ifdef __NR_brk
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SC_ALLOW(brk),
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#endif
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#ifdef __NR_clock_gettime
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SC_ALLOW(clock_gettime),
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#endif
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#if defined(__x86_64__) && defined(__ILP32__) && defined(__X32_SYSCALL_BIT)
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SECCOMP_ALLOW(__NR_clock_gettime & ~__X32_SYSCALL_BIT),
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#endif
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#ifdef __NR_clock_gettime64
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SC_ALLOW(clock_gettime64),
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#endif
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#ifdef __NR_close
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SC_ALLOW(close),
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#endif
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#ifdef __NR_epoll_ctl
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SC_ALLOW(epoll_ctl),
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#endif
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#ifdef __NR_epoll_pwait
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SC_ALLOW(epoll_pwait),
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#endif
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#ifdef __NR_epoll_wait
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SC_ALLOW(epoll_wait),
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#endif
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#ifdef __NR_exit
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SC_ALLOW(exit),
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#endif
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#ifdef __NR_exit_group
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SC_ALLOW(exit_group),
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#endif
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#ifdef __NR_fcntl
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SC_ALLOW(fcntl),
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#endif
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#ifdef __NR_fcntl64
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SC_ALLOW(fcntl64),
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#endif
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#ifdef __NR_fstat
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SC_ALLOW(fstat),
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#endif
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#ifdef __NR_getdents64
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SC_ALLOW(getdents64),
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#endif
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#ifdef __NR_getpid
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SC_ALLOW(getpid),
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#endif
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#ifdef __NR_getrandom
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SC_ALLOW(getrandom),
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#endif
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#ifdef __NR_gettimeofday
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SC_ALLOW(gettimeofday),
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#endif
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#ifdef __NR_ioctl
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/* allow ioctl only on fd 1, glibc doing stuff? */
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SC_ALLOW_ARG(__NR_ioctl, 0, 1),
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#endif
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#ifdef __NR_lseek
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SC_ALLOW(lseek),
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#endif
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#ifdef __NR_madvise
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SC_ALLOW(madvise),
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#endif
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#ifdef __NR_mmap
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SC_ALLOW(mmap),
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#endif
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#ifdef __NR_mmap2
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SC_ALLOW(mmap2),
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#endif
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#ifdef __NR_munmap
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SC_ALLOW(munmap),
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#endif
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#ifdef __NR_newfstatat
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SC_ALLOW(newfstatat),
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#endif
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#ifdef __NR_oldfstat
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SC_ALLOW(oldfstat),
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#endif
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#ifdef __NR_openat
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SC_ALLOW(openat),
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#endif
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#ifdef __NR_prlimit64
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SC_ALLOW(prlimit64),
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#endif
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#ifdef __NR_read
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SC_ALLOW(read),
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#endif
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#ifdef __NR_recvmsg
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SC_ALLOW(recvmsg),
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#endif
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#ifdef __NR_redav
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SC_ALLOW(redav),
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#endif
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#ifdef __NR_rt_sigaction
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SC_ALLOW(rt_sigaction),
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#endif
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#ifdef __NR_rt_sigreturn
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SC_ALLOW(rt_sigreturn),
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#endif
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#ifdef __NR_sendmsg
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SC_ALLOW(sendmsg),
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#endif
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#ifdef __NR_statx
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SC_ALLOW(statx),
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#endif
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#ifdef __NR_write
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SC_ALLOW(write),
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#endif
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#ifdef __NR_writev
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SC_ALLOW(writev),
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#endif
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/* disallow enything else */
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BPF_STMT(BPF_RET | BPF_K, SC_FAIL),
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};
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#ifdef SC_DEBUG
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#include <signal.h>
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#include <unistd.h>
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static void
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sandbox_seccomp_violation(int signum, siginfo_t *info, void *ctx)
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{
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(void)signum;
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(void)ctx;
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fprintf(stderr, "%s: unexpected system call (arch:0x%x,syscall:%d @ %p)\n",
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__func__, info->si_arch, info->si_syscall, info->si_call_addr);
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_exit(1);
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}
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static void
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sandbox_seccomp_catch_sigsys(void)
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{
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struct sigaction act;
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sigset_t mask;
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memset(&act, 0, sizeof(act));
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sigemptyset(&mask);
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sigaddset(&mask, SIGSYS);
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act.sa_sigaction = &sandbox_seccomp_violation;
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act.sa_flags = SA_SIGINFO;
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if (sigaction(SIGSYS, &act, NULL) == -1)
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fatal("%s: sigaction(SIGSYS): %s",
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__func__, strerror(errno));
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if (sigprocmask(SIG_UNBLOCK, &mask, NULL) == -1)
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fatal("%s: sigprocmask(SIGSYS): %s\n",
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__func__, strerror(errno));
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}
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#endif /* SC_DEBUG */
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void
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sandbox_server_process(void)
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{
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struct sock_fprog prog = {
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.len = (unsigned short) (sizeof(filter) / sizeof(filter[0])),
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.filter = filter,
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};
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#ifdef SC_DEBUG
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sandbox_seccomp_catch_sigsys();
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#endif
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if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) == -1)
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fatal("%s: prctl(PR_SET_NO_NEW_PRIVS): %s",
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__func__, strerror(errno));
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if (prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog) == -1)
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fatal("%s: prctl(PR_SET_SECCOMP): %s\n",
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__func__, strerror(errno));
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}
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void
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sandbox_executor_process(void)
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{
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/* We cannot use seccomp for the executor process because we
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* don't know what the child will do. Also, our filter will
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* be inherited so the child cannot set its own seccomp
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* policy. */
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return;
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}
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void
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sandbox_logger_process(void)
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{
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/* To be honest, here we could use a seccomp policy to only
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* allow writev(2) and memory allocations. */
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return;
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}
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#elif defined(__OpenBSD__)
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#include <unistd.h>
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void
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sandbox_server_process(void)
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{
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struct vhost *h;
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struct location *l;
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TAILQ_FOREACH(h, &hosts, vhosts) {
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TAILQ_FOREACH(l, &h->locations, locations) {
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if (l->dir == NULL)
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continue;
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if (unveil(l->dir, "r") == -1)
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fatal("unveil %s for domain %s",
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l->dir,
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h->domain);
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}
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}
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if (pledge("stdio recvfd rpath inet", NULL) == -1)
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fatal("pledge");
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}
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void
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sandbox_executor_process(void)
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{
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struct vhost *h;
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struct location *l;
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struct fcgi *f;
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size_t i;
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TAILQ_FOREACH(h, &hosts, vhosts) {
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TAILQ_FOREACH(l, &h->locations, locations) {
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if (l->dir == NULL)
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continue;
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/* r so we can chdir into the correct directory */
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if (unveil(l->dir, "rx") == -1)
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fatal("unveil %s for domain %s",
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l->dir, h->domain);
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}
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}
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for (i = 0; i < FCGI_MAX; i++) {
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f = &fcgi[i];
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if (f->path != NULL) {
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if (unveil(f->path, "rw") == -1)
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fatal("unveil %s", f->path);
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}
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if (f->prog != NULL) {
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if (unveil(f->prog, "rx") == -1)
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|
fatal("unveil %s", f->prog);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* rpath: to chdir into the correct directory
|
|
* proc exec: CGI
|
|
* dns inet unix: FastCGI
|
|
*/
|
|
if (pledge("stdio rpath sendfd proc exec dns inet unix", NULL))
|
|
err(1, "pledge");
|
|
}
|
|
|
|
void
|
|
sandbox_logger_process(void)
|
|
{
|
|
if (pledge("stdio recvfd", NULL) == -1)
|
|
err(1, "pledge");
|
|
}
|
|
|
|
#else
|
|
|
|
#warning "No sandbox method known for this OS"
|
|
|
|
void
|
|
sandbox_server_process(void)
|
|
{
|
|
return;
|
|
}
|
|
|
|
void
|
|
sandbox_executor_process(void)
|
|
{
|
|
log_notice(NULL, "no sandbox method known for this OS");
|
|
}
|
|
|
|
void
|
|
sandbox_logger_process(void)
|
|
{
|
|
return;
|
|
}
|
|
|
|
#endif
|