+static void *
+xmalloc(size_t size)
+{
+ void *p = malloc(size);
+ if (!p)
+ die("Out of memory");
+ return p;
+}
+
+/*** Syscall rules ***/
+
+static const char * const syscall_names[] = {
+#include "syscall-table.h"
+};
+#define NUM_SYSCALLS ARRAY_SIZE(syscall_names)
+#define NUM_ACTIONS (NUM_SYSCALLS+64)
+
+enum action {
+ A_DEFAULT, // Use the default action
+ A_NO, // Always forbid
+ A_YES, // Always permit
+ A_FILENAME, // Permit if arg1 is a known filename
+ A_LIBERAL = 128, // Valid only in liberal mode
+};
+
+static unsigned char syscall_action[NUM_ACTIONS] = {
+#define S(x) [__NR_##x]
+
+ // Syscalls permitted for specific file names
+ S(open) = A_FILENAME,
+ S(creat) = A_FILENAME,
+ S(unlink) = A_FILENAME,
+ S(oldstat) = A_FILENAME,
+ S(access) = A_FILENAME,
+ S(oldlstat) = A_FILENAME,
+ S(truncate) = A_FILENAME,
+ S(stat) = A_FILENAME,
+ S(lstat) = A_FILENAME,
+ S(truncate64) = A_FILENAME,
+ S(stat64) = A_FILENAME,
+ S(lstat64) = A_FILENAME,
+ S(readlink) = A_FILENAME,
+
+ // Syscalls permitted always
+ S(exit) = A_YES,
+ S(read) = A_YES,
+ S(write) = A_YES,
+ S(close) = A_YES,
+ S(lseek) = A_YES,
+ S(getpid) = A_YES,
+ S(getuid) = A_YES,
+ S(oldfstat) = A_YES,
+ S(dup) = A_YES,
+ S(brk) = A_YES,
+ S(getgid) = A_YES,
+ S(geteuid) = A_YES,
+ S(getegid) = A_YES,
+ S(dup2) = A_YES,
+ S(ftruncate) = A_YES,
+ S(fstat) = A_YES,
+ S(personality) = A_YES,
+ S(_llseek) = A_YES,
+ S(readv) = A_YES,
+ S(writev) = A_YES,
+ S(getresuid) = A_YES,
+#ifdef __NR_pread64
+ S(pread64) = A_YES,
+ S(pwrite64) = A_YES,
+#else
+ S(pread) = A_YES,
+ S(pwrite) = A_YES,
+#endif
+ S(ftruncate64) = A_YES,
+ S(fstat64) = A_YES,
+ S(fcntl) = A_YES,
+ S(fcntl64) = A_YES,
+ S(mmap) = A_YES,
+ S(munmap) = A_YES,
+ S(ioctl) = A_YES,
+ S(uname) = A_YES,
+ S(gettid) = A_YES,
+ S(set_thread_area) = A_YES,
+ S(get_thread_area) = A_YES,
+ S(exit_group) = A_YES,
+
+ // Syscalls permitted only in liberal mode
+ S(time) = A_YES | A_LIBERAL,
+ S(alarm) = A_YES | A_LIBERAL,
+ S(pause) = A_YES | A_LIBERAL,
+ S(signal) = A_YES | A_LIBERAL,
+ S(fchmod) = A_YES | A_LIBERAL,
+ S(sigaction) = A_YES | A_LIBERAL,
+ S(sgetmask) = A_YES | A_LIBERAL,
+ S(ssetmask) = A_YES | A_LIBERAL,
+ S(sigsuspend) = A_YES | A_LIBERAL,
+ S(sigpending) = A_YES | A_LIBERAL,
+ S(getrlimit) = A_YES | A_LIBERAL,
+ S(getrusage) = A_YES | A_LIBERAL,
+ S(ugetrlimit) = A_YES | A_LIBERAL,
+ S(gettimeofday) = A_YES | A_LIBERAL,
+ S(select) = A_YES | A_LIBERAL,
+ S(readdir) = A_YES | A_LIBERAL,
+ S(setitimer) = A_YES | A_LIBERAL,
+ S(getitimer) = A_YES | A_LIBERAL,
+ S(sigreturn) = A_YES | A_LIBERAL,
+ S(mprotect) = A_YES | A_LIBERAL,
+ S(sigprocmask) = A_YES | A_LIBERAL,
+ S(getdents) = A_YES | A_LIBERAL,
+ S(getdents64) = A_YES | A_LIBERAL,
+ S(_newselect) = A_YES | A_LIBERAL,
+ S(fdatasync) = A_YES | A_LIBERAL,
+ S(mremap) = A_YES | A_LIBERAL,
+ S(poll) = A_YES | A_LIBERAL,
+ S(getcwd) = A_YES | A_LIBERAL,
+ S(nanosleep) = A_YES | A_LIBERAL,
+ S(rt_sigreturn) = A_YES | A_LIBERAL,
+ S(rt_sigaction) = A_YES | A_LIBERAL,
+ S(rt_sigprocmask) = A_YES | A_LIBERAL,
+ S(rt_sigpending) = A_YES | A_LIBERAL,
+ S(rt_sigtimedwait) = A_YES | A_LIBERAL,
+ S(rt_sigqueueinfo) = A_YES | A_LIBERAL,
+ S(rt_sigsuspend) = A_YES | A_LIBERAL,
+ S(mmap2) = A_YES | A_LIBERAL,
+ S(_sysctl) = A_YES | A_LIBERAL,
+#undef S
+};
+
+static const char *
+syscall_name(unsigned int id, char *buf)
+{
+ if (id < NUM_SYSCALLS && syscall_names[id])
+ return syscall_names[id];
+ else
+ {
+ sprintf(buf, "#%d", id);
+ return buf;
+ }
+}
+
+static int
+syscall_by_name(char *name)
+{
+ for (unsigned int i=0; i<NUM_SYSCALLS; i++)
+ if (syscall_names[i] && !strcmp(syscall_names[i], name))
+ return i;
+ if (name[0] == '#')
+ name++;
+ if (!*name)
+ return -1;
+ char *ep;
+ unsigned long l = strtoul(name, &ep, 0);
+ if (*ep)
+ return -1;
+ if (l >= NUM_ACTIONS)
+ return NUM_ACTIONS;
+ return l;
+}
+
+static int
+set_syscall_action(char *a)
+{
+ char *sep = strchr(a, '=');
+ enum action act = A_YES;
+ if (sep)
+ {
+ *sep++ = 0;
+ if (!strcmp(sep, "yes"))
+ act = A_YES;
+ else if (!strcmp(sep, "no"))
+ act = A_NO;
+ else if (!strcmp(sep, "file"))
+ act = A_FILENAME;
+ else
+ return 0;
+ }
+
+ int sys = syscall_by_name(a);
+ if (sys < 0)
+ die("Unknown syscall `%s'", a);
+ if (sys >= NUM_ACTIONS)
+ die("Syscall `%s' out of range", a);
+ syscall_action[sys] = act;
+ return 1;
+}
+
+/*** Path rules ***/
+
+struct path_rule {
+ char *path;
+ enum action action;
+ struct path_rule *next;
+};
+
+static struct path_rule default_path_rules[] = {
+ { "/etc/", A_YES },
+ { "/lib/", A_YES },
+ { "/usr/lib/", A_YES },
+ { "/opt/lib/", A_YES },
+ { "/usr/share/zoneinfo/", A_YES },
+ { "/usr/share/locale/", A_YES },
+ { "/dev/null", A_YES },
+ { "/dev/zero", A_YES },
+ { "/proc/meminfo", A_YES },
+ { "/proc/self/stat", A_YES },
+ { "/proc/self/exe", A_YES }, // Needed by FPC 2.0.x runtime
+};
+
+static struct path_rule *user_path_rules;
+static struct path_rule **last_path_rule = &user_path_rules;
+
+static int
+set_path_action(char *a)
+{
+ char *sep = strchr(a, '=');
+ enum action act = A_YES;
+ if (sep)
+ {
+ *sep++ = 0;
+ if (!strcmp(sep, "yes"))
+ act = A_YES;
+ else if (!strcmp(sep, "no"))
+ act = A_NO;
+ else
+ return 0;
+ }
+
+ struct path_rule *r = xmalloc(sizeof(*r) + strlen(a) + 1);
+ r->path = (char *)(r+1);
+ strcpy(r->path, a);
+ r->action = act;
+ r->next = NULL;
+ *last_path_rule = r;
+ last_path_rule = &r->next;
+ return 1;
+}
+
+static enum action
+match_path_rule(struct path_rule *r, char *path)
+{
+ char *rr = r->path;
+ while (*rr)
+ if (*rr++ != *path++)
+ {
+ if (rr[-1] == '/' && !path[-1])
+ break;
+ return A_DEFAULT;
+ }
+ if (rr > r->path && rr[-1] != '/' && *path)
+ return A_DEFAULT;
+ return r->action;
+}
+
+/*** Environment rules ***/
+
+struct env_rule {
+ char *var; // Variable to match
+ char *val; // ""=clear, NULL=inherit
+ int var_len;
+ struct env_rule *next;
+};
+
+static struct env_rule *first_env_rule;
+static struct env_rule **last_env_rule = &first_env_rule;
+
+static struct env_rule default_env_rules[] = {
+ { "LIBC_FATAL_STDERR_", "1" }
+};
+
+static int
+set_env_action(char *a0)
+{
+ struct env_rule *r = xmalloc(sizeof(*r) + strlen(a0) + 1);
+ char *a = (char *)(r+1);
+ strcpy(a, a0);
+
+ char *sep = strchr(a, '=');
+ if (sep == a)
+ return 0;
+ r->var = a;
+ if (sep)
+ {
+ *sep++ = 0;
+ r->val = sep;
+ }
+ else
+ r->val = NULL;
+ *last_env_rule = r;
+ last_env_rule = &r->next;
+ r->next = NULL;
+ return 1;
+}
+
+static int
+match_env_var(char *env_entry, struct env_rule *r)
+{
+ if (strncmp(env_entry, r->var, r->var_len))
+ return 0;
+ return (env_entry[r->var_len] == '=');
+}
+
+static void
+apply_env_rule(char **env, int *env_sizep, struct env_rule *r)
+{
+ // First remove the variable if already set
+ int pos = 0;
+ while (pos < *env_sizep && !match_env_var(env[pos], r))
+ pos++;
+ if (pos < *env_sizep)
+ {
+ (*env_sizep)--;
+ env[pos] = env[*env_sizep];
+ env[*env_sizep] = NULL;
+ }
+
+ // What is the new value?
+ char *new;
+ if (r->val)
+ {
+ if (!r->val[0])
+ return;
+ new = xmalloc(r->var_len + 1 + strlen(r->val) + 1);
+ sprintf(new, "%s=%s", r->var, r->val);
+ }
+ else
+ {
+ pos = 0;
+ while (environ[pos] && !match_env_var(environ[pos], r))
+ pos++;
+ if (!(new = environ[pos]))
+ return;
+ }
+
+ // Add it at the end of the array
+ env[(*env_sizep)++] = new;
+ env[*env_sizep] = NULL;
+}
+
+static char **
+setup_environment(void)
+{
+ // Link built-in rules with user rules
+ for (int i=ARRAY_SIZE(default_env_rules)-1; i >= 0; i--)
+ {
+ default_env_rules[i].next = first_env_rule;
+ first_env_rule = &default_env_rules[i];
+ }
+
+ // Scan the original environment
+ char **orig_env = environ;
+ int orig_size = 0;
+ while (orig_env[orig_size])
+ orig_size++;
+
+ // For each rule, reserve one more slot and calculate length
+ int num_rules = 0;
+ for (struct env_rule *r = first_env_rule; r; r=r->next)
+ {
+ num_rules++;
+ r->var_len = strlen(r->var);
+ }
+
+ // Create a new environment
+ char **env = xmalloc((orig_size + num_rules + 1) * sizeof(char *));
+ int size;
+ if (pass_environ)
+ {
+ memcpy(env, environ, orig_size * sizeof(char *));
+ size = orig_size;
+ }
+ else
+ size = 0;
+ env[size] = NULL;
+
+ // Apply the rules one by one
+ for (struct env_rule *r = first_env_rule; r; r=r->next)
+ apply_env_rule(env, &size, r);
+
+ // Return the new env and pass some gossip
+ if (verbose > 1)
+ {
+ fprintf(stderr, "Passing environment:\n");
+ for (int i=0; env[i]; i++)
+ fprintf(stderr, "\t%s\n", env[i]);
+ }
+ return env;
+}
+
+/*** Syscall checks ***/
+