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30 FILE_RCSID("@(#)$File: seccomp.c,v 1.8 2019/02/24 18:12:04 christos Exp $")
34 #include <seccomp.h> /* libseccomp */
35 #include <sys/prctl.h> /* prctl */
36 #include <sys/socket.h>
41 #define DENY_RULE(call) \
43 if (seccomp_rule_add (ctx, SCMP_ACT_KILL, SCMP_SYS(call), 0) == -1) \
45 while (/*CONSTCOND*/0)
46 #define ALLOW_RULE(call) \
48 if (seccomp_rule_add (ctx, SCMP_ACT_ALLOW, SCMP_SYS(call), 0) == -1) \
50 while (/*CONSTCOND*/0)
52 static scmp_filter_ctx ctx;
56 enable_sandbox_basic(void)
59 if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) == -1)
62 if (prctl(PR_SET_DUMPABLE, 0, 0, 0, 0) == -1)
65 // initialize the filter
66 ctx = seccomp_init(SCMP_ACT_ALLOW);
75 DENY_RULE(clock_adjtime);
76 DENY_RULE(create_module);
77 DENY_RULE(delete_module);
78 DENY_RULE(fanotify_init);
79 DENY_RULE(finit_module);
80 DENY_RULE(get_kernel_syms);
81 DENY_RULE(get_mempolicy);
82 DENY_RULE(init_module);
84 DENY_RULE(io_destroy);
85 DENY_RULE(io_getevents);
90 DENY_RULE(ioprio_set);
92 #ifdef __NR_kexec_file_load
93 DENY_RULE(kexec_file_load);
95 DENY_RULE(kexec_load);
97 DENY_RULE(lookup_dcookie);
99 DENY_RULE(nfsservctl);
100 DENY_RULE(migrate_pages);
101 DENY_RULE(modify_ldt);
103 DENY_RULE(move_pages);
104 DENY_RULE(name_to_handle_at);
105 DENY_RULE(open_by_handle_at);
106 DENY_RULE(perf_event_open);
107 DENY_RULE(pivot_root);
108 DENY_RULE(process_vm_readv);
109 DENY_RULE(process_vm_writev);
112 DENY_RULE(remap_file_pages);
113 DENY_RULE(request_key);
114 DENY_RULE(set_mempolicy);
124 // blocking dangerous syscalls that file should not need
130 // applying filter...
131 if (seccomp_load (ctx) == -1)
133 // free ctx after the filter has been loaded into the kernel
134 seccomp_release(ctx);
138 seccomp_release(ctx);
144 enable_sandbox_full(void)
147 // prevent child processes from getting more priv e.g. via setuid,
149 if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) == -1)
152 if (prctl(PR_SET_DUMPABLE, 0, 0, 0, 0) == -1)
155 // initialize the filter
156 ctx = seccomp_init(SCMP_ACT_KILL);
165 ALLOW_RULE(exit_group);
170 ALLOW_RULE(getdents);
171 #ifdef __NR_getdents64
172 ALLOW_RULE(getdents64);
182 ALLOW_RULE(mprotect);
185 #ifdef __NR_newfstatat
186 ALLOW_RULE(newfstatat);
192 ALLOW_RULE(readlink);
193 ALLOW_RULE(rt_sigaction);
194 ALLOW_RULE(rt_sigprocmask);
195 ALLOW_RULE(rt_sigreturn);
205 // needed by valgrind
208 ALLOW_RULE(rt_sigtimedwait);
212 /* special restrictions for socket, only allow AF_UNIX/AF_LOCAL */
213 if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(socket), 1,
214 SCMP_CMP(0, SCMP_CMP_EQ, AF_UNIX)) == -1)
217 if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(socket), 1,
218 SCMP_CMP(0, SCMP_CMP_EQ, AF_LOCAL)) == -1)
222 /* special restrictions for open, prevent opening files for writing */
223 if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(open), 1,
224 SCMP_CMP(1, SCMP_CMP_MASKED_EQ, O_WRONLY | O_RDWR, 0)) == -1)
227 if (seccomp_rule_add(ctx, SCMP_ACT_ERRNO(EACCES), SCMP_SYS(open), 1,
228 SCMP_CMP(1, SCMP_CMP_MASKED_EQ, O_WRONLY, O_WRONLY)) == -1)
231 if (seccomp_rule_add(ctx, SCMP_ACT_ERRNO(EACCES), SCMP_SYS(open), 1,
232 SCMP_CMP(1, SCMP_CMP_MASKED_EQ, O_RDWR, O_RDWR)) == -1)
237 if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(write), 1,
238 SCMP_CMP(0, SCMP_CMP_EQ, 2)) == -1)
242 // applying filter...
243 if (seccomp_load(ctx) == -1)
245 // free ctx after the filter has been loaded into the kernel
246 seccomp_release(ctx);
250 // something went wrong
251 seccomp_release(ctx);