158d83921SDag-Erling Smørgrav /*
258d83921SDag-Erling Smørgrav  * Copyright (c) 2012 Will Drewry <wad@dataspill.org>
3*4d3fc8b0SEd Maste  * Copyright (c) 2015,2017,2019,2020,2023 Damien Miller <djm@mindrot.org>
458d83921SDag-Erling Smørgrav  *
558d83921SDag-Erling Smørgrav  * Permission to use, copy, modify, and distribute this software for any
658d83921SDag-Erling Smørgrav  * purpose with or without fee is hereby granted, provided that the above
758d83921SDag-Erling Smørgrav  * copyright notice and this permission notice appear in all copies.
858d83921SDag-Erling Smørgrav  *
958d83921SDag-Erling Smørgrav  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
1058d83921SDag-Erling Smørgrav  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
1158d83921SDag-Erling Smørgrav  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
1258d83921SDag-Erling Smørgrav  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
1358d83921SDag-Erling Smørgrav  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
1458d83921SDag-Erling Smørgrav  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
1558d83921SDag-Erling Smørgrav  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
1658d83921SDag-Erling Smørgrav  */
1758d83921SDag-Erling Smørgrav 
1858d83921SDag-Erling Smørgrav /*
1958d83921SDag-Erling Smørgrav  * Uncomment the SANDBOX_SECCOMP_FILTER_DEBUG macro below to help diagnose
2058d83921SDag-Erling Smørgrav  * filter breakage during development. *Do not* use this in production,
2158d83921SDag-Erling Smørgrav  * as it relies on making library calls that are unsafe in signal context.
2258d83921SDag-Erling Smørgrav  *
2358d83921SDag-Erling Smørgrav  * Instead, live systems the auditctl(8) may be used to monitor failures.
2458d83921SDag-Erling Smørgrav  * E.g.
2558d83921SDag-Erling Smørgrav  *   auditctl -a task,always -F uid=<privsep uid>
2658d83921SDag-Erling Smørgrav  */
27f374ba41SEd Maste /* #define SANDBOX_SECCOMP_FILTER_DEBUG 1 */
2858d83921SDag-Erling Smørgrav 
2938a52bd3SEd Maste #if 0
3038a52bd3SEd Maste /*
3138a52bd3SEd Maste  * For older toolchains, it may be necessary to use the kernel
3238a52bd3SEd Maste  * headers directly.
3338a52bd3SEd Maste  */
3458d83921SDag-Erling Smørgrav #ifdef SANDBOX_SECCOMP_FILTER_DEBUG
3558d83921SDag-Erling Smørgrav # include <asm/siginfo.h>
3658d83921SDag-Erling Smørgrav # define __have_siginfo_t 1
3758d83921SDag-Erling Smørgrav # define __have_sigval_t 1
3858d83921SDag-Erling Smørgrav # define __have_sigevent_t 1
3958d83921SDag-Erling Smørgrav #endif /* SANDBOX_SECCOMP_FILTER_DEBUG */
4038a52bd3SEd Maste #endif
4158d83921SDag-Erling Smørgrav 
4258d83921SDag-Erling Smørgrav #include "includes.h"
4358d83921SDag-Erling Smørgrav 
4458d83921SDag-Erling Smørgrav #ifdef SANDBOX_SECCOMP_FILTER
4558d83921SDag-Erling Smørgrav 
4658d83921SDag-Erling Smørgrav #include <sys/types.h>
4758d83921SDag-Erling Smørgrav #include <sys/resource.h>
4858d83921SDag-Erling Smørgrav #include <sys/prctl.h>
4919261079SEd Maste #include <sys/mman.h>
5019261079SEd Maste #include <sys/syscall.h>
5158d83921SDag-Erling Smørgrav 
52*4d3fc8b0SEd Maste #include <linux/futex.h>
53557f75e5SDag-Erling Smørgrav #include <linux/net.h>
5458d83921SDag-Erling Smørgrav #include <linux/audit.h>
5558d83921SDag-Erling Smørgrav #include <linux/filter.h>
5658d83921SDag-Erling Smørgrav #include <linux/seccomp.h>
5758d83921SDag-Erling Smørgrav #include <elf.h>
5858d83921SDag-Erling Smørgrav 
5958d83921SDag-Erling Smørgrav #include <asm/unistd.h>
604f52dfbbSDag-Erling Smørgrav #ifdef __s390__
614f52dfbbSDag-Erling Smørgrav #include <asm/zcrypt.h>
624f52dfbbSDag-Erling Smørgrav #endif
6358d83921SDag-Erling Smørgrav 
6458d83921SDag-Erling Smørgrav #include <errno.h>
6558d83921SDag-Erling Smørgrav #include <signal.h>
6658d83921SDag-Erling Smørgrav #include <stdarg.h>
6758d83921SDag-Erling Smørgrav #include <stddef.h>  /* for offsetof */
6858d83921SDag-Erling Smørgrav #include <stdio.h>
6958d83921SDag-Erling Smørgrav #include <stdlib.h>
7058d83921SDag-Erling Smørgrav #include <string.h>
7158d83921SDag-Erling Smørgrav #include <unistd.h>
7258d83921SDag-Erling Smørgrav 
7358d83921SDag-Erling Smørgrav #include "log.h"
7458d83921SDag-Erling Smørgrav #include "ssh-sandbox.h"
7558d83921SDag-Erling Smørgrav #include "xmalloc.h"
7658d83921SDag-Erling Smørgrav 
7758d83921SDag-Erling Smørgrav /* Linux seccomp_filter sandbox */
7858d83921SDag-Erling Smørgrav #define SECCOMP_FILTER_FAIL SECCOMP_RET_KILL
7958d83921SDag-Erling Smørgrav 
8058d83921SDag-Erling Smørgrav /* Use a signal handler to emit violations when debugging */
8158d83921SDag-Erling Smørgrav #ifdef SANDBOX_SECCOMP_FILTER_DEBUG
8258d83921SDag-Erling Smørgrav # undef SECCOMP_FILTER_FAIL
8358d83921SDag-Erling Smørgrav # define SECCOMP_FILTER_FAIL SECCOMP_RET_TRAP
8458d83921SDag-Erling Smørgrav #endif /* SANDBOX_SECCOMP_FILTER_DEBUG */
8558d83921SDag-Erling Smørgrav 
86d93a896eSDag-Erling Smørgrav #if __BYTE_ORDER == __LITTLE_ENDIAN
87d93a896eSDag-Erling Smørgrav # define ARG_LO_OFFSET  0
88d93a896eSDag-Erling Smørgrav # define ARG_HI_OFFSET  sizeof(uint32_t)
89d93a896eSDag-Erling Smørgrav #elif __BYTE_ORDER == __BIG_ENDIAN
90d93a896eSDag-Erling Smørgrav # define ARG_LO_OFFSET  sizeof(uint32_t)
91d93a896eSDag-Erling Smørgrav # define ARG_HI_OFFSET  0
92d93a896eSDag-Erling Smørgrav #else
93d93a896eSDag-Erling Smørgrav #error "Unknown endianness"
94d93a896eSDag-Erling Smørgrav #endif
95d93a896eSDag-Erling Smørgrav 
9658d83921SDag-Erling Smørgrav /* Simple helpers to avoid manual errors (but larger BPF programs). */
9758d83921SDag-Erling Smørgrav #define SC_DENY(_nr, _errno) \
98d93a896eSDag-Erling Smørgrav 	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (_nr), 0, 1), \
9958d83921SDag-Erling Smørgrav 	BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ERRNO|(_errno))
10058d83921SDag-Erling Smørgrav #define SC_ALLOW(_nr) \
101d93a896eSDag-Erling Smørgrav 	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (_nr), 0, 1), \
10258d83921SDag-Erling Smørgrav 	BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW)
103557f75e5SDag-Erling Smørgrav #define SC_ALLOW_ARG(_nr, _arg_nr, _arg_val) \
104d93a896eSDag-Erling Smørgrav 	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (_nr), 0, 6), \
10519261079SEd Maste 	/* load and test syscall argument, low word */ \
106557f75e5SDag-Erling Smørgrav 	BPF_STMT(BPF_LD+BPF_W+BPF_ABS, \
107d93a896eSDag-Erling Smørgrav 	    offsetof(struct seccomp_data, args[(_arg_nr)]) + ARG_LO_OFFSET), \
108d93a896eSDag-Erling Smørgrav 	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, \
109d93a896eSDag-Erling Smørgrav 	    ((_arg_val) & 0xFFFFFFFF), 0, 3), \
11019261079SEd Maste 	/* load and test syscall argument, high word */ \
111d93a896eSDag-Erling Smørgrav 	BPF_STMT(BPF_LD+BPF_W+BPF_ABS, \
112d93a896eSDag-Erling Smørgrav 	    offsetof(struct seccomp_data, args[(_arg_nr)]) + ARG_HI_OFFSET), \
113d93a896eSDag-Erling Smørgrav 	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, \
114d93a896eSDag-Erling Smørgrav 	    (((uint32_t)((uint64_t)(_arg_val) >> 32)) & 0xFFFFFFFF), 0, 1), \
115557f75e5SDag-Erling Smørgrav 	BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW), \
116557f75e5SDag-Erling Smørgrav 	/* reload syscall number; all rules expect it in accumulator */ \
117557f75e5SDag-Erling Smørgrav 	BPF_STMT(BPF_LD+BPF_W+BPF_ABS, \
118557f75e5SDag-Erling Smørgrav 		offsetof(struct seccomp_data, nr))
11919261079SEd Maste /* Allow if syscall argument contains only values in mask */
12019261079SEd Maste #define SC_ALLOW_ARG_MASK(_nr, _arg_nr, _arg_mask) \
12119261079SEd Maste 	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (_nr), 0, 8), \
12219261079SEd Maste 	/* load, mask and test syscall argument, low word */ \
12319261079SEd Maste 	BPF_STMT(BPF_LD+BPF_W+BPF_ABS, \
12419261079SEd Maste 	    offsetof(struct seccomp_data, args[(_arg_nr)]) + ARG_LO_OFFSET), \
12519261079SEd Maste 	BPF_STMT(BPF_ALU+BPF_AND+BPF_K, ~((_arg_mask) & 0xFFFFFFFF)), \
12619261079SEd Maste 	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, 0, 0, 4), \
12719261079SEd Maste 	/* load, mask and test syscall argument, high word */ \
12819261079SEd Maste 	BPF_STMT(BPF_LD+BPF_W+BPF_ABS, \
12919261079SEd Maste 	    offsetof(struct seccomp_data, args[(_arg_nr)]) + ARG_HI_OFFSET), \
13019261079SEd Maste 	BPF_STMT(BPF_ALU+BPF_AND+BPF_K, \
13119261079SEd Maste 	    ~(((uint32_t)((uint64_t)(_arg_mask) >> 32)) & 0xFFFFFFFF)), \
13219261079SEd Maste 	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, 0, 0, 1), \
13319261079SEd Maste 	BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW), \
13419261079SEd Maste 	/* reload syscall number; all rules expect it in accumulator */ \
13519261079SEd Maste 	BPF_STMT(BPF_LD+BPF_W+BPF_ABS, \
13619261079SEd Maste 		offsetof(struct seccomp_data, nr))
137*4d3fc8b0SEd Maste /* Deny unless syscall argument contains only values in mask */
138*4d3fc8b0SEd Maste #define SC_DENY_UNLESS_ARG_MASK(_nr, _arg_nr, _arg_mask, _errno) \
139*4d3fc8b0SEd Maste 	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (_nr), 0, 8), \
140*4d3fc8b0SEd Maste 	/* load, mask and test syscall argument, low word */ \
141*4d3fc8b0SEd Maste 	BPF_STMT(BPF_LD+BPF_W+BPF_ABS, \
142*4d3fc8b0SEd Maste 	    offsetof(struct seccomp_data, args[(_arg_nr)]) + ARG_LO_OFFSET), \
143*4d3fc8b0SEd Maste 	BPF_STMT(BPF_ALU+BPF_AND+BPF_K, ~((_arg_mask) & 0xFFFFFFFF)), \
144*4d3fc8b0SEd Maste 	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, 0, 0, 3), \
145*4d3fc8b0SEd Maste 	/* load, mask and test syscall argument, high word */ \
146*4d3fc8b0SEd Maste 	BPF_STMT(BPF_LD+BPF_W+BPF_ABS, \
147*4d3fc8b0SEd Maste 	    offsetof(struct seccomp_data, args[(_arg_nr)]) + ARG_HI_OFFSET), \
148*4d3fc8b0SEd Maste 	BPF_STMT(BPF_ALU+BPF_AND+BPF_K, \
149*4d3fc8b0SEd Maste 	    ~(((uint32_t)((uint64_t)(_arg_mask) >> 32)) & 0xFFFFFFFF)), \
150*4d3fc8b0SEd Maste 	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, 0, 1, 0), \
151*4d3fc8b0SEd Maste 	BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ERRNO|(_errno)), \
152*4d3fc8b0SEd Maste 	/* reload syscall number; all rules expect it in accumulator */ \
153*4d3fc8b0SEd Maste 	BPF_STMT(BPF_LD+BPF_W+BPF_ABS, \
154*4d3fc8b0SEd Maste 		offsetof(struct seccomp_data, nr))
155*4d3fc8b0SEd Maste #define SC_DENY_UNLESS_MASK(_nr, _arg_nr, _arg_val, _errno) \
156*4d3fc8b0SEd Maste /* Special handling for futex(2) that combines a bitmap and operation number */
157*4d3fc8b0SEd Maste #if defined(__NR_futex) || defined(__NR_futex_time64)
158*4d3fc8b0SEd Maste #define SC_FUTEX_MASK (FUTEX_PRIVATE_FLAG|FUTEX_CLOCK_REALTIME)
159*4d3fc8b0SEd Maste #define SC_ALLOW_FUTEX_OP(_nr, _op) \
160*4d3fc8b0SEd Maste 	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (_nr), 0, 8), \
161*4d3fc8b0SEd Maste 	/* load syscall argument, low word */ \
162*4d3fc8b0SEd Maste 	BPF_STMT(BPF_LD+BPF_W+BPF_ABS, \
163*4d3fc8b0SEd Maste 	    offsetof(struct seccomp_data, args[1]) + ARG_LO_OFFSET), \
164*4d3fc8b0SEd Maste 	/* mask off allowed bitmap values, low word */ \
165*4d3fc8b0SEd Maste 	BPF_STMT(BPF_ALU+BPF_AND+BPF_K, ~(SC_FUTEX_MASK & 0xFFFFFFFF)), \
166*4d3fc8b0SEd Maste 	/* test operation number, low word */ \
167*4d3fc8b0SEd Maste 	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, ((_op) & 0xFFFFFFFF), 0, 4), \
168*4d3fc8b0SEd Maste 	/* load syscall argument, high word */ \
169*4d3fc8b0SEd Maste 	BPF_STMT(BPF_LD+BPF_W+BPF_ABS, \
170*4d3fc8b0SEd Maste 	    offsetof(struct seccomp_data, args[1]) + ARG_HI_OFFSET), \
171*4d3fc8b0SEd Maste 	/* mask off allowed bitmap values, high word */ \
172*4d3fc8b0SEd Maste 	BPF_STMT(BPF_ALU+BPF_AND+BPF_K, \
173*4d3fc8b0SEd Maste 	    ~(((uint32_t)((uint64_t)SC_FUTEX_MASK >> 32)) & 0xFFFFFFFF)), \
174*4d3fc8b0SEd Maste 	/* test operation number, high word */ \
175*4d3fc8b0SEd Maste 	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, \
176*4d3fc8b0SEd Maste 	    (((uint32_t)((uint64_t)(_op) >> 32)) & 0xFFFFFFFF), 0, 1), \
177*4d3fc8b0SEd Maste 	BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW), \
178*4d3fc8b0SEd Maste 	/* reload syscall number; all rules expect it in accumulator */ \
179*4d3fc8b0SEd Maste 	BPF_STMT(BPF_LD+BPF_W+BPF_ABS, offsetof(struct seccomp_data, nr))
180*4d3fc8b0SEd Maste 
181*4d3fc8b0SEd Maste /* Use this for both __NR_futex and __NR_futex_time64 */
182*4d3fc8b0SEd Maste # define SC_FUTEX(_nr) \
183*4d3fc8b0SEd Maste 	SC_ALLOW_FUTEX_OP(__NR_futex, FUTEX_WAIT), \
184*4d3fc8b0SEd Maste 	SC_ALLOW_FUTEX_OP(__NR_futex, FUTEX_WAIT_BITSET), \
185*4d3fc8b0SEd Maste 	SC_ALLOW_FUTEX_OP(__NR_futex, FUTEX_WAKE), \
186*4d3fc8b0SEd Maste 	SC_ALLOW_FUTEX_OP(__NR_futex, FUTEX_WAKE_BITSET), \
187*4d3fc8b0SEd Maste 	SC_ALLOW_FUTEX_OP(__NR_futex, FUTEX_REQUEUE), \
188*4d3fc8b0SEd Maste 	SC_ALLOW_FUTEX_OP(__NR_futex, FUTEX_CMP_REQUEUE)
189*4d3fc8b0SEd Maste #endif /* __NR_futex || __NR_futex_time64 */
190*4d3fc8b0SEd Maste 
191*4d3fc8b0SEd Maste #if defined(__NR_mmap) || defined(__NR_mmap2)
192*4d3fc8b0SEd Maste # ifdef MAP_FIXED_NOREPLACE
193*4d3fc8b0SEd Maste #  define SC_MMAP_FLAGS MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED|MAP_FIXED_NOREPLACE
194*4d3fc8b0SEd Maste # else
195*4d3fc8b0SEd Maste #  define SC_MMAP_FLAGS MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED
196*4d3fc8b0SEd Maste # endif /* MAP_FIXED_NOREPLACE */
197*4d3fc8b0SEd Maste /* Use this for both __NR_mmap and __NR_mmap2 variants */
198*4d3fc8b0SEd Maste # define SC_MMAP(_nr) \
199*4d3fc8b0SEd Maste 	SC_DENY_UNLESS_ARG_MASK(_nr, 3, SC_MMAP_FLAGS, EINVAL), \
200*4d3fc8b0SEd Maste 	SC_ALLOW_ARG_MASK(_nr, 2, PROT_READ|PROT_WRITE|PROT_NONE)
201*4d3fc8b0SEd Maste #endif /* __NR_mmap || __NR_mmap2 */
20258d83921SDag-Erling Smørgrav 
20358d83921SDag-Erling Smørgrav /* Syscall filtering set for preauth. */
20458d83921SDag-Erling Smørgrav static const struct sock_filter preauth_insns[] = {
20558d83921SDag-Erling Smørgrav 	/* Ensure the syscall arch convention is as expected. */
20658d83921SDag-Erling Smørgrav 	BPF_STMT(BPF_LD+BPF_W+BPF_ABS,
20758d83921SDag-Erling Smørgrav 		offsetof(struct seccomp_data, arch)),
20858d83921SDag-Erling Smørgrav 	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, SECCOMP_AUDIT_ARCH, 1, 0),
20958d83921SDag-Erling Smørgrav 	BPF_STMT(BPF_RET+BPF_K, SECCOMP_FILTER_FAIL),
21058d83921SDag-Erling Smørgrav 	/* Load the syscall number for checking. */
21158d83921SDag-Erling Smørgrav 	BPF_STMT(BPF_LD+BPF_W+BPF_ABS,
21258d83921SDag-Erling Smørgrav 		offsetof(struct seccomp_data, nr)),
213557f75e5SDag-Erling Smørgrav 
214557f75e5SDag-Erling Smørgrav 	/* Syscalls to non-fatally deny */
215076ad2f8SDag-Erling Smørgrav #ifdef __NR_lstat
216d93a896eSDag-Erling Smørgrav 	SC_DENY(__NR_lstat, EACCES),
217076ad2f8SDag-Erling Smørgrav #endif
218076ad2f8SDag-Erling Smørgrav #ifdef __NR_lstat64
219d93a896eSDag-Erling Smørgrav 	SC_DENY(__NR_lstat64, EACCES),
220076ad2f8SDag-Erling Smørgrav #endif
221557f75e5SDag-Erling Smørgrav #ifdef __NR_fstat
222d93a896eSDag-Erling Smørgrav 	SC_DENY(__NR_fstat, EACCES),
223557f75e5SDag-Erling Smørgrav #endif
224557f75e5SDag-Erling Smørgrav #ifdef __NR_fstat64
225d93a896eSDag-Erling Smørgrav 	SC_DENY(__NR_fstat64, EACCES),
226557f75e5SDag-Erling Smørgrav #endif
22719261079SEd Maste #ifdef __NR_fstatat64
22819261079SEd Maste 	SC_DENY(__NR_fstatat64, EACCES),
22919261079SEd Maste #endif
230557f75e5SDag-Erling Smørgrav #ifdef __NR_open
231d93a896eSDag-Erling Smørgrav 	SC_DENY(__NR_open, EACCES),
232557f75e5SDag-Erling Smørgrav #endif
233557f75e5SDag-Erling Smørgrav #ifdef __NR_openat
234d93a896eSDag-Erling Smørgrav 	SC_DENY(__NR_openat, EACCES),
235557f75e5SDag-Erling Smørgrav #endif
236557f75e5SDag-Erling Smørgrav #ifdef __NR_newfstatat
237d93a896eSDag-Erling Smørgrav 	SC_DENY(__NR_newfstatat, EACCES),
238557f75e5SDag-Erling Smørgrav #endif
239557f75e5SDag-Erling Smørgrav #ifdef __NR_stat
240d93a896eSDag-Erling Smørgrav 	SC_DENY(__NR_stat, EACCES),
24158d83921SDag-Erling Smørgrav #endif
242557f75e5SDag-Erling Smørgrav #ifdef __NR_stat64
243d93a896eSDag-Erling Smørgrav 	SC_DENY(__NR_stat64, EACCES),
244b83788ffSDag-Erling Smørgrav #endif
24519261079SEd Maste #ifdef __NR_shmget
24619261079SEd Maste 	SC_DENY(__NR_shmget, EACCES),
24719261079SEd Maste #endif
24819261079SEd Maste #ifdef __NR_shmat
24919261079SEd Maste 	SC_DENY(__NR_shmat, EACCES),
25019261079SEd Maste #endif
25119261079SEd Maste #ifdef __NR_shmdt
25219261079SEd Maste 	SC_DENY(__NR_shmdt, EACCES),
25319261079SEd Maste #endif
25419261079SEd Maste #ifdef __NR_ipc
25519261079SEd Maste 	SC_DENY(__NR_ipc, EACCES),
25619261079SEd Maste #endif
25719261079SEd Maste #ifdef __NR_statx
25819261079SEd Maste 	SC_DENY(__NR_statx, EACCES),
25919261079SEd Maste #endif
260557f75e5SDag-Erling Smørgrav 
261557f75e5SDag-Erling Smørgrav 	/* Syscalls to permit */
262557f75e5SDag-Erling Smørgrav #ifdef __NR_brk
263d93a896eSDag-Erling Smørgrav 	SC_ALLOW(__NR_brk),
26458d83921SDag-Erling Smørgrav #endif
265557f75e5SDag-Erling Smørgrav #ifdef __NR_clock_gettime
266d93a896eSDag-Erling Smørgrav 	SC_ALLOW(__NR_clock_gettime),
267557f75e5SDag-Erling Smørgrav #endif
26819261079SEd Maste #ifdef __NR_clock_gettime64
26919261079SEd Maste 	SC_ALLOW(__NR_clock_gettime64),
27019261079SEd Maste #endif
271557f75e5SDag-Erling Smørgrav #ifdef __NR_close
272d93a896eSDag-Erling Smørgrav 	SC_ALLOW(__NR_close),
273557f75e5SDag-Erling Smørgrav #endif
274557f75e5SDag-Erling Smørgrav #ifdef __NR_exit
275d93a896eSDag-Erling Smørgrav 	SC_ALLOW(__NR_exit),
276557f75e5SDag-Erling Smørgrav #endif
277557f75e5SDag-Erling Smørgrav #ifdef __NR_exit_group
278d93a896eSDag-Erling Smørgrav 	SC_ALLOW(__NR_exit_group),
279557f75e5SDag-Erling Smørgrav #endif
2802f513db7SEd Maste #ifdef __NR_futex
281*4d3fc8b0SEd Maste 	SC_FUTEX(__NR_futex),
2822f513db7SEd Maste #endif
28319261079SEd Maste #ifdef __NR_futex_time64
284*4d3fc8b0SEd Maste 	SC_FUTEX(__NR_futex_time64),
28519261079SEd Maste #endif
286190cef3dSDag-Erling Smørgrav #ifdef __NR_geteuid
287190cef3dSDag-Erling Smørgrav 	SC_ALLOW(__NR_geteuid),
288190cef3dSDag-Erling Smørgrav #endif
289190cef3dSDag-Erling Smørgrav #ifdef __NR_geteuid32
290190cef3dSDag-Erling Smørgrav 	SC_ALLOW(__NR_geteuid32),
291190cef3dSDag-Erling Smørgrav #endif
292557f75e5SDag-Erling Smørgrav #ifdef __NR_getpgid
293d93a896eSDag-Erling Smørgrav 	SC_ALLOW(__NR_getpgid),
294557f75e5SDag-Erling Smørgrav #endif
295557f75e5SDag-Erling Smørgrav #ifdef __NR_getpid
296d93a896eSDag-Erling Smørgrav 	SC_ALLOW(__NR_getpid),
297557f75e5SDag-Erling Smørgrav #endif
298acc1a9efSDag-Erling Smørgrav #ifdef __NR_getrandom
299d93a896eSDag-Erling Smørgrav 	SC_ALLOW(__NR_getrandom),
300acc1a9efSDag-Erling Smørgrav #endif
3011323ec57SEd Maste #ifdef __NR_gettid
3021323ec57SEd Maste 	SC_ALLOW(__NR_gettid),
3031323ec57SEd Maste #endif
304557f75e5SDag-Erling Smørgrav #ifdef __NR_gettimeofday
305d93a896eSDag-Erling Smørgrav 	SC_ALLOW(__NR_gettimeofday),
306557f75e5SDag-Erling Smørgrav #endif
307190cef3dSDag-Erling Smørgrav #ifdef __NR_getuid
308190cef3dSDag-Erling Smørgrav 	SC_ALLOW(__NR_getuid),
309190cef3dSDag-Erling Smørgrav #endif
310190cef3dSDag-Erling Smørgrav #ifdef __NR_getuid32
311190cef3dSDag-Erling Smørgrav 	SC_ALLOW(__NR_getuid32),
312190cef3dSDag-Erling Smørgrav #endif
313557f75e5SDag-Erling Smørgrav #ifdef __NR_madvise
314*4d3fc8b0SEd Maste 	SC_ALLOW_ARG(__NR_madvise, 2, MADV_NORMAL),
315*4d3fc8b0SEd Maste # ifdef MADV_FREE
316*4d3fc8b0SEd Maste 	SC_ALLOW_ARG(__NR_madvise, 2, MADV_FREE),
317*4d3fc8b0SEd Maste # endif
318*4d3fc8b0SEd Maste # ifdef MADV_DONTNEED
319*4d3fc8b0SEd Maste 	SC_ALLOW_ARG(__NR_madvise, 2, MADV_DONTNEED),
320*4d3fc8b0SEd Maste # endif
321*4d3fc8b0SEd Maste # ifdef MADV_DONTFORK
322*4d3fc8b0SEd Maste 	SC_ALLOW_ARG(__NR_madvise, 2, MADV_DONTFORK),
323*4d3fc8b0SEd Maste # endif
324*4d3fc8b0SEd Maste # ifdef MADV_DONTDUMP
325*4d3fc8b0SEd Maste 	SC_ALLOW_ARG(__NR_madvise, 2, MADV_DONTDUMP),
326*4d3fc8b0SEd Maste # endif
327*4d3fc8b0SEd Maste # ifdef MADV_WIPEONFORK
328*4d3fc8b0SEd Maste 	SC_ALLOW_ARG(__NR_madvise, 2, MADV_WIPEONFORK),
329*4d3fc8b0SEd Maste # endif
330*4d3fc8b0SEd Maste 	SC_DENY(__NR_madvise, EINVAL),
33158d83921SDag-Erling Smørgrav #endif
33258d83921SDag-Erling Smørgrav #ifdef __NR_mmap
333*4d3fc8b0SEd Maste 	SC_MMAP(__NR_mmap),
33458d83921SDag-Erling Smørgrav #endif
335557f75e5SDag-Erling Smørgrav #ifdef __NR_mmap2
336*4d3fc8b0SEd Maste 	SC_MMAP(__NR_mmap2),
33719261079SEd Maste #endif
33819261079SEd Maste #ifdef __NR_mprotect
33919261079SEd Maste 	SC_ALLOW_ARG_MASK(__NR_mprotect, 2, PROT_READ|PROT_WRITE|PROT_NONE),
340a0ee8cc6SDag-Erling Smørgrav #endif
341557f75e5SDag-Erling Smørgrav #ifdef __NR_mremap
342d93a896eSDag-Erling Smørgrav 	SC_ALLOW(__NR_mremap),
343557f75e5SDag-Erling Smørgrav #endif
344557f75e5SDag-Erling Smørgrav #ifdef __NR_munmap
345d93a896eSDag-Erling Smørgrav 	SC_ALLOW(__NR_munmap),
346557f75e5SDag-Erling Smørgrav #endif
347190cef3dSDag-Erling Smørgrav #ifdef __NR_nanosleep
348190cef3dSDag-Erling Smørgrav 	SC_ALLOW(__NR_nanosleep),
349190cef3dSDag-Erling Smørgrav #endif
35019261079SEd Maste #ifdef __NR_clock_nanosleep
35119261079SEd Maste 	SC_ALLOW(__NR_clock_nanosleep),
35219261079SEd Maste #endif
35319261079SEd Maste #ifdef __NR_clock_nanosleep_time64
35419261079SEd Maste 	SC_ALLOW(__NR_clock_nanosleep_time64),
35519261079SEd Maste #endif
35619261079SEd Maste #ifdef __NR_clock_gettime64
35719261079SEd Maste 	SC_ALLOW(__NR_clock_gettime64),
35819261079SEd Maste #endif
359557f75e5SDag-Erling Smørgrav #ifdef __NR__newselect
360d93a896eSDag-Erling Smørgrav 	SC_ALLOW(__NR__newselect),
361557f75e5SDag-Erling Smørgrav #endif
3621323ec57SEd Maste #ifdef __NR_ppoll
3631323ec57SEd Maste 	SC_ALLOW(__NR_ppoll),
3641323ec57SEd Maste #endif
36558def461SEd Maste #ifdef __NR_ppoll_time64
36658def461SEd Maste 	SC_ALLOW(__NR_ppoll_time64),
36758def461SEd Maste #endif
368557f75e5SDag-Erling Smørgrav #ifdef __NR_poll
369d93a896eSDag-Erling Smørgrav 	SC_ALLOW(__NR_poll),
370557f75e5SDag-Erling Smørgrav #endif
371557f75e5SDag-Erling Smørgrav #ifdef __NR_pselect6
372d93a896eSDag-Erling Smørgrav 	SC_ALLOW(__NR_pselect6),
373557f75e5SDag-Erling Smørgrav #endif
37419261079SEd Maste #ifdef __NR_pselect6_time64
37519261079SEd Maste 	SC_ALLOW(__NR_pselect6_time64),
37619261079SEd Maste #endif
377557f75e5SDag-Erling Smørgrav #ifdef __NR_read
378d93a896eSDag-Erling Smørgrav 	SC_ALLOW(__NR_read),
379557f75e5SDag-Erling Smørgrav #endif
38058d83921SDag-Erling Smørgrav #ifdef __NR_rt_sigprocmask
381d93a896eSDag-Erling Smørgrav 	SC_ALLOW(__NR_rt_sigprocmask),
382557f75e5SDag-Erling Smørgrav #endif
383557f75e5SDag-Erling Smørgrav #ifdef __NR_select
384d93a896eSDag-Erling Smørgrav 	SC_ALLOW(__NR_select),
385557f75e5SDag-Erling Smørgrav #endif
386557f75e5SDag-Erling Smørgrav #ifdef __NR_shutdown
387d93a896eSDag-Erling Smørgrav 	SC_ALLOW(__NR_shutdown),
388557f75e5SDag-Erling Smørgrav #endif
389557f75e5SDag-Erling Smørgrav #ifdef __NR_sigprocmask
390d93a896eSDag-Erling Smørgrav 	SC_ALLOW(__NR_sigprocmask),
39158d83921SDag-Erling Smørgrav #endif
392557f75e5SDag-Erling Smørgrav #ifdef __NR_time
393d93a896eSDag-Erling Smørgrav 	SC_ALLOW(__NR_time),
394557f75e5SDag-Erling Smørgrav #endif
395557f75e5SDag-Erling Smørgrav #ifdef __NR_write
396d93a896eSDag-Erling Smørgrav 	SC_ALLOW(__NR_write),
397557f75e5SDag-Erling Smørgrav #endif
398f374ba41SEd Maste #ifdef __NR_writev
399f374ba41SEd Maste 	SC_ALLOW(__NR_writev),
400f374ba41SEd Maste #endif
401557f75e5SDag-Erling Smørgrav #ifdef __NR_socketcall
402d93a896eSDag-Erling Smørgrav 	SC_ALLOW_ARG(__NR_socketcall, 0, SYS_SHUTDOWN),
4034f52dfbbSDag-Erling Smørgrav 	SC_DENY(__NR_socketcall, EACCES),
404d93a896eSDag-Erling Smørgrav #endif
405d93a896eSDag-Erling Smørgrav #if defined(__NR_ioctl) && defined(__s390__)
406d93a896eSDag-Erling Smørgrav 	/* Allow ioctls for ICA crypto card on s390 */
407d93a896eSDag-Erling Smørgrav 	SC_ALLOW_ARG(__NR_ioctl, 1, Z90STAT_STATUS_MASK),
408d93a896eSDag-Erling Smørgrav 	SC_ALLOW_ARG(__NR_ioctl, 1, ICARSAMODEXPO),
409d93a896eSDag-Erling Smørgrav 	SC_ALLOW_ARG(__NR_ioctl, 1, ICARSACRT),
41019261079SEd Maste 	SC_ALLOW_ARG(__NR_ioctl, 1, ZSECSENDCPRB),
41119261079SEd Maste 	/* Allow ioctls for EP11 crypto card on s390 */
41219261079SEd Maste 	SC_ALLOW_ARG(__NR_ioctl, 1, ZSENDEP11CPRB),
413d93a896eSDag-Erling Smørgrav #endif
414d93a896eSDag-Erling Smørgrav #if defined(__x86_64__) && defined(__ILP32__) && defined(__X32_SYSCALL_BIT)
415d93a896eSDag-Erling Smørgrav 	/*
416d93a896eSDag-Erling Smørgrav 	 * On Linux x32, the clock_gettime VDSO falls back to the
417d93a896eSDag-Erling Smørgrav 	 * x86-64 syscall under some circumstances, e.g.
418d93a896eSDag-Erling Smørgrav 	 * https://bugs.debian.org/849923
419d93a896eSDag-Erling Smørgrav 	 */
4204f52dfbbSDag-Erling Smørgrav 	SC_ALLOW(__NR_clock_gettime & ~__X32_SYSCALL_BIT),
421557f75e5SDag-Erling Smørgrav #endif
422557f75e5SDag-Erling Smørgrav 
423557f75e5SDag-Erling Smørgrav 	/* Default deny */
42458d83921SDag-Erling Smørgrav 	BPF_STMT(BPF_RET+BPF_K, SECCOMP_FILTER_FAIL),
42558d83921SDag-Erling Smørgrav };
42658d83921SDag-Erling Smørgrav 
42758d83921SDag-Erling Smørgrav static const struct sock_fprog preauth_program = {
42858d83921SDag-Erling Smørgrav 	.len = (unsigned short)(sizeof(preauth_insns)/sizeof(preauth_insns[0])),
42958d83921SDag-Erling Smørgrav 	.filter = (struct sock_filter *)preauth_insns,
43058d83921SDag-Erling Smørgrav };
43158d83921SDag-Erling Smørgrav 
43258d83921SDag-Erling Smørgrav struct ssh_sandbox {
43358d83921SDag-Erling Smørgrav 	pid_t child_pid;
43458d83921SDag-Erling Smørgrav };
43558d83921SDag-Erling Smørgrav 
43658d83921SDag-Erling Smørgrav struct ssh_sandbox *
ssh_sandbox_init(struct monitor * monitor)437f7167e0eSDag-Erling Smørgrav ssh_sandbox_init(struct monitor *monitor)
43858d83921SDag-Erling Smørgrav {
43958d83921SDag-Erling Smørgrav 	struct ssh_sandbox *box;
44058d83921SDag-Erling Smørgrav 
44158d83921SDag-Erling Smørgrav 	/*
44258d83921SDag-Erling Smørgrav 	 * Strictly, we don't need to maintain any state here but we need
44358d83921SDag-Erling Smørgrav 	 * to return non-NULL to satisfy the API.
44458d83921SDag-Erling Smørgrav 	 */
44558d83921SDag-Erling Smørgrav 	debug3("%s: preparing seccomp filter sandbox", __func__);
44658d83921SDag-Erling Smørgrav 	box = xcalloc(1, sizeof(*box));
44758d83921SDag-Erling Smørgrav 	box->child_pid = 0;
44858d83921SDag-Erling Smørgrav 
44958d83921SDag-Erling Smørgrav 	return box;
45058d83921SDag-Erling Smørgrav }
45158d83921SDag-Erling Smørgrav 
45258d83921SDag-Erling Smørgrav #ifdef SANDBOX_SECCOMP_FILTER_DEBUG
45358d83921SDag-Erling Smørgrav extern struct monitor *pmonitor;
45438a52bd3SEd Maste void mm_log_handler(LogLevel level, int forced, const char *msg, void *ctx);
45558d83921SDag-Erling Smørgrav 
45658d83921SDag-Erling Smørgrav static void
ssh_sandbox_violation(int signum,siginfo_t * info,void * void_context)45758d83921SDag-Erling Smørgrav ssh_sandbox_violation(int signum, siginfo_t *info, void *void_context)
45858d83921SDag-Erling Smørgrav {
45958d83921SDag-Erling Smørgrav 	char msg[256];
46058d83921SDag-Erling Smørgrav 
46158d83921SDag-Erling Smørgrav 	snprintf(msg, sizeof(msg),
46258d83921SDag-Erling Smørgrav 	    "%s: unexpected system call (arch:0x%x,syscall:%d @ %p)",
46358d83921SDag-Erling Smørgrav 	    __func__, info->si_arch, info->si_syscall, info->si_call_addr);
46438a52bd3SEd Maste 	mm_log_handler(SYSLOG_LEVEL_FATAL, 0, msg, pmonitor);
46558d83921SDag-Erling Smørgrav 	_exit(1);
46658d83921SDag-Erling Smørgrav }
46758d83921SDag-Erling Smørgrav 
46858d83921SDag-Erling Smørgrav static void
ssh_sandbox_child_debugging(void)46958d83921SDag-Erling Smørgrav ssh_sandbox_child_debugging(void)
47058d83921SDag-Erling Smørgrav {
47158d83921SDag-Erling Smørgrav 	struct sigaction act;
47258d83921SDag-Erling Smørgrav 	sigset_t mask;
47358d83921SDag-Erling Smørgrav 
47458d83921SDag-Erling Smørgrav 	debug3("%s: installing SIGSYS handler", __func__);
47558d83921SDag-Erling Smørgrav 	memset(&act, 0, sizeof(act));
47658d83921SDag-Erling Smørgrav 	sigemptyset(&mask);
47758d83921SDag-Erling Smørgrav 	sigaddset(&mask, SIGSYS);
47858d83921SDag-Erling Smørgrav 
47958d83921SDag-Erling Smørgrav 	act.sa_sigaction = &ssh_sandbox_violation;
48058d83921SDag-Erling Smørgrav 	act.sa_flags = SA_SIGINFO;
48158d83921SDag-Erling Smørgrav 	if (sigaction(SIGSYS, &act, NULL) == -1)
48258d83921SDag-Erling Smørgrav 		fatal("%s: sigaction(SIGSYS): %s", __func__, strerror(errno));
48358d83921SDag-Erling Smørgrav 	if (sigprocmask(SIG_UNBLOCK, &mask, NULL) == -1)
48458d83921SDag-Erling Smørgrav 		fatal("%s: sigprocmask(SIGSYS): %s",
48558d83921SDag-Erling Smørgrav 		    __func__, strerror(errno));
48658d83921SDag-Erling Smørgrav }
48758d83921SDag-Erling Smørgrav #endif /* SANDBOX_SECCOMP_FILTER_DEBUG */
48858d83921SDag-Erling Smørgrav 
48958d83921SDag-Erling Smørgrav void
ssh_sandbox_child(struct ssh_sandbox * box)49058d83921SDag-Erling Smørgrav ssh_sandbox_child(struct ssh_sandbox *box)
49158d83921SDag-Erling Smørgrav {
4921323ec57SEd Maste 	struct rlimit rl_zero, rl_one = {.rlim_cur = 1, .rlim_max = 1};
49358d83921SDag-Erling Smørgrav 	int nnp_failed = 0;
49458d83921SDag-Erling Smørgrav 
49558d83921SDag-Erling Smørgrav 	/* Set rlimits for completeness if possible. */
49658d83921SDag-Erling Smørgrav 	rl_zero.rlim_cur = rl_zero.rlim_max = 0;
49758d83921SDag-Erling Smørgrav 	if (setrlimit(RLIMIT_FSIZE, &rl_zero) == -1)
49858d83921SDag-Erling Smørgrav 		fatal("%s: setrlimit(RLIMIT_FSIZE, { 0, 0 }): %s",
49958d83921SDag-Erling Smørgrav 			__func__, strerror(errno));
5001323ec57SEd Maste 	/*
5011323ec57SEd Maste 	 * Cannot use zero for nfds, because poll(2) will fail with
5021323ec57SEd Maste 	 * errno=EINVAL if npfds>RLIMIT_NOFILE.
5031323ec57SEd Maste 	 */
5041323ec57SEd Maste 	if (setrlimit(RLIMIT_NOFILE, &rl_one) == -1)
50558d83921SDag-Erling Smørgrav 		fatal("%s: setrlimit(RLIMIT_NOFILE, { 0, 0 }): %s",
50658d83921SDag-Erling Smørgrav 			__func__, strerror(errno));
50758d83921SDag-Erling Smørgrav 	if (setrlimit(RLIMIT_NPROC, &rl_zero) == -1)
50858d83921SDag-Erling Smørgrav 		fatal("%s: setrlimit(RLIMIT_NPROC, { 0, 0 }): %s",
50958d83921SDag-Erling Smørgrav 			__func__, strerror(errno));
51058d83921SDag-Erling Smørgrav 
51158d83921SDag-Erling Smørgrav #ifdef SANDBOX_SECCOMP_FILTER_DEBUG
51258d83921SDag-Erling Smørgrav 	ssh_sandbox_child_debugging();
51358d83921SDag-Erling Smørgrav #endif /* SANDBOX_SECCOMP_FILTER_DEBUG */
51458d83921SDag-Erling Smørgrav 
51558d83921SDag-Erling Smørgrav 	debug3("%s: setting PR_SET_NO_NEW_PRIVS", __func__);
51658d83921SDag-Erling Smørgrav 	if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) == -1) {
51758d83921SDag-Erling Smørgrav 		debug("%s: prctl(PR_SET_NO_NEW_PRIVS): %s",
51858d83921SDag-Erling Smørgrav 		    __func__, strerror(errno));
51958d83921SDag-Erling Smørgrav 		nnp_failed = 1;
52058d83921SDag-Erling Smørgrav 	}
52158d83921SDag-Erling Smørgrav 	debug3("%s: attaching seccomp filter program", __func__);
52258d83921SDag-Erling Smørgrav 	if (prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &preauth_program) == -1)
52358d83921SDag-Erling Smørgrav 		debug("%s: prctl(PR_SET_SECCOMP): %s",
52458d83921SDag-Erling Smørgrav 		    __func__, strerror(errno));
52558d83921SDag-Erling Smørgrav 	else if (nnp_failed)
52658d83921SDag-Erling Smørgrav 		fatal("%s: SECCOMP_MODE_FILTER activated but "
52758d83921SDag-Erling Smørgrav 		    "PR_SET_NO_NEW_PRIVS failed", __func__);
52858d83921SDag-Erling Smørgrav }
52958d83921SDag-Erling Smørgrav 
53058d83921SDag-Erling Smørgrav void
ssh_sandbox_parent_finish(struct ssh_sandbox * box)53158d83921SDag-Erling Smørgrav ssh_sandbox_parent_finish(struct ssh_sandbox *box)
53258d83921SDag-Erling Smørgrav {
53358d83921SDag-Erling Smørgrav 	free(box);
53458d83921SDag-Erling Smørgrav 	debug3("%s: finished", __func__);
53558d83921SDag-Erling Smørgrav }
53658d83921SDag-Erling Smørgrav 
53758d83921SDag-Erling Smørgrav void
ssh_sandbox_parent_preauth(struct ssh_sandbox * box,pid_t child_pid)53858d83921SDag-Erling Smørgrav ssh_sandbox_parent_preauth(struct ssh_sandbox *box, pid_t child_pid)
53958d83921SDag-Erling Smørgrav {
54058d83921SDag-Erling Smørgrav 	box->child_pid = child_pid;
54158d83921SDag-Erling Smørgrav }
54258d83921SDag-Erling Smørgrav 
54358d83921SDag-Erling Smørgrav #endif /* SANDBOX_SECCOMP_FILTER */
544