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30 FILE_RCSID("@(#)$File: seccomp.c,v 1.15 2020/05/30 23:56:26 christos Exp $")
34 #include <seccomp.h> /* libseccomp */
35 #include <sys/prctl.h> /* prctl */
36 #include <sys/ioctl.h>
37 #include <sys/socket.h>
42 #define DENY_RULE(call) \
44 if (seccomp_rule_add (ctx, SCMP_ACT_KILL, SCMP_SYS(call), 0) == -1) \
46 while (/*CONSTCOND*/0)
47 #define ALLOW_RULE(call) \
49 if (seccomp_rule_add (ctx, SCMP_ACT_ALLOW, SCMP_SYS(call), 0) == -1) \
51 while (/*CONSTCOND*/0)
53 #define ALLOW_IOCTL_RULE(param) \
55 if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(ioctl), 1, \
56 SCMP_CMP(1, SCMP_CMP_EQ, param)) == -1) \
58 while (/*CONSTCOND*/0)
60 static scmp_filter_ctx ctx;
63 enable_sandbox_basic(void)
66 if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) == -1)
69 if (prctl(PR_SET_DUMPABLE, 0, 0, 0, 0) == -1)
72 // initialize the filter
73 ctx = seccomp_init(SCMP_ACT_ALLOW);
82 DENY_RULE(clock_adjtime);
83 DENY_RULE(create_module);
84 DENY_RULE(delete_module);
85 DENY_RULE(fanotify_init);
86 DENY_RULE(finit_module);
87 DENY_RULE(get_kernel_syms);
88 DENY_RULE(get_mempolicy);
89 DENY_RULE(init_module);
91 DENY_RULE(io_destroy);
92 DENY_RULE(io_getevents);
97 DENY_RULE(ioprio_set);
99 #ifdef __NR_kexec_file_load
100 DENY_RULE(kexec_file_load);
102 DENY_RULE(kexec_load);
104 DENY_RULE(lookup_dcookie);
106 DENY_RULE(nfsservctl);
107 DENY_RULE(migrate_pages);
108 DENY_RULE(modify_ldt);
110 DENY_RULE(move_pages);
111 DENY_RULE(name_to_handle_at);
112 DENY_RULE(open_by_handle_at);
113 DENY_RULE(perf_event_open);
114 DENY_RULE(pivot_root);
115 DENY_RULE(process_vm_readv);
116 DENY_RULE(process_vm_writev);
119 DENY_RULE(remap_file_pages);
120 DENY_RULE(request_key);
121 DENY_RULE(set_mempolicy);
131 // blocking dangerous syscalls that file should not need
137 // applying filter...
138 if (seccomp_load (ctx) == -1)
140 // free ctx after the filter has been loaded into the kernel
141 seccomp_release(ctx);
145 seccomp_release(ctx);
151 enable_sandbox_full(void)
154 // prevent child processes from getting more priv e.g. via setuid,
156 if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) == -1)
159 if (prctl(PR_SET_DUMPABLE, 0, 0, 0, 0) == -1)
162 // initialize the filter
163 ctx = seccomp_init(SCMP_ACT_KILL);
172 ALLOW_RULE(exit_group);
180 ALLOW_RULE(getdents);
181 #ifdef __NR_getdents64
182 ALLOW_RULE(getdents64);
185 // called in src/compress.c under sread
186 ALLOW_IOCTL_RULE(FIONREAD);
189 // musl libc may call ioctl TIOCGWINSZ on stdout
190 ALLOW_IOCTL_RULE(TIOCGWINSZ);
193 // glibc may call ioctl TCGETS on stdout on physical terminal
194 ALLOW_IOCTL_RULE(TCGETS);
203 ALLOW_RULE(mprotect);
206 #ifdef __NR_newfstatat
207 ALLOW_RULE(newfstatat);
213 ALLOW_RULE(readlink);
214 #ifdef __NR_readlinkat
215 ALLOW_RULE(readlinkat);
217 ALLOW_RULE(rt_sigaction);
218 ALLOW_RULE(rt_sigprocmask);
219 ALLOW_RULE(rt_sigreturn);
224 ALLOW_RULE(umask); // Used in file_pipe2file()
225 ALLOW_RULE(getpid); // Used by glibc in file_pipe2file()
231 // needed by valgrind
233 ALLOW_RULE(rt_sigtimedwait);
237 /* special restrictions for socket, only allow AF_UNIX/AF_LOCAL */
238 if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(socket), 1,
239 SCMP_CMP(0, SCMP_CMP_EQ, AF_UNIX)) == -1)
242 if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(socket), 1,
243 SCMP_CMP(0, SCMP_CMP_EQ, AF_LOCAL)) == -1)
247 /* special restrictions for open, prevent opening files for writing */
248 if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(open), 1,
249 SCMP_CMP(1, SCMP_CMP_MASKED_EQ, O_WRONLY | O_RDWR, 0)) == -1)
252 if (seccomp_rule_add(ctx, SCMP_ACT_ERRNO(EACCES), SCMP_SYS(open), 1,
253 SCMP_CMP(1, SCMP_CMP_MASKED_EQ, O_WRONLY, O_WRONLY)) == -1)
256 if (seccomp_rule_add(ctx, SCMP_ACT_ERRNO(EACCES), SCMP_SYS(open), 1,
257 SCMP_CMP(1, SCMP_CMP_MASKED_EQ, O_RDWR, O_RDWR)) == -1)
262 if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(write), 1,
263 SCMP_CMP(0, SCMP_CMP_EQ, 2)) == -1)
267 // applying filter...
268 if (seccomp_load(ctx) == -1)
270 // free ctx after the filter has been loaded into the kernel
271 seccomp_release(ctx);
275 // something went wrong
276 seccomp_release(ctx);