+
+bool Popen(const char* Args[], FileFd &Fd, pid_t &Child, FileFd::OpenMode Mode)
+{
+ int fd;
+ if (Mode != FileFd::ReadOnly && Mode != FileFd::WriteOnly)
+ return _error->Error("Popen supports ReadOnly (x)or WriteOnly mode only");
+
+ int Pipe[2] = {-1, -1};
+ if(pipe(Pipe) != 0)
+ {
+ return _error->Errno("pipe", _("Failed to create subprocess IPC"));
+ return NULL;
+ }
+ std::set<int> keep_fds;
+ keep_fds.insert(Pipe[0]);
+ keep_fds.insert(Pipe[1]);
+ Child = ExecFork(keep_fds);
+ if(Child < 0)
+ return _error->Errno("fork", "Failed to fork");
+ if(Child == 0)
+ {
+ if(Mode == FileFd::ReadOnly)
+ {
+ close(Pipe[0]);
+ fd = Pipe[1];
+ }
+ else if(Mode == FileFd::WriteOnly)
+ {
+ close(Pipe[1]);
+ fd = Pipe[0];
+ }
+
+ if(Mode == FileFd::ReadOnly)
+ {
+ dup2(fd, 1);
+ dup2(fd, 2);
+ } else if(Mode == FileFd::WriteOnly)
+ dup2(fd, 0);
+
+ execv(Args[0], (char**)Args);
+ _exit(100);
+ }
+ if(Mode == FileFd::ReadOnly)
+ {
+ close(Pipe[1]);
+ fd = Pipe[0];
+ } else if(Mode == FileFd::WriteOnly)
+ {
+ close(Pipe[0]);
+ fd = Pipe[1];
+ }
+ Fd.OpenDescriptor(fd, Mode, FileFd::None, true);
+
+ return true;
+}
+
+bool DropPrivs()
+{
+ /* uid will be 0 in the end, but gid might be different anyway */
+ uid_t old_uid = getuid();
+ gid_t old_gid = getgid();
+
+ if (old_uid != 0)
+ return true;
+ if(_config->FindB("Debug::NoDropPrivs", false) == true)
+ return true;
+
+ const std::string nobody = _config->Find("APT::User::Nobody", "_apt");
+ struct passwd *pw = getpwnam(nobody.c_str());
+ if (pw == NULL)
+ return _error->Warning("No user %s, can not drop rights", nobody.c_str());
+
+#if __gnu_linux__
+ // see prctl(2), needs linux3.5
+ int ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0,0, 0);
+ if(ret < 0)
+ _error->Warning("PR_SET_NO_NEW_PRIVS failed with %i", ret);
+#endif
+
+ if (setgroups(1, &pw->pw_gid) != 1)
+ return _error->Errno("setgroups", "Failed to setgroups");
+
+ if (setegid(pw->pw_gid) != 0)
+ return _error->Errno("setegid", "Failed to setegid");
+
+ if (setgid(pw->pw_gid) != 0)
+ return _error->Errno("setgid", "Failed to setgid");
+
+ if (setuid(pw->pw_uid) != 0)
+ return _error->Errno("setuid", "Failed to setuid");
+ // the seteuid() is probably uneeded (at least thats what the linux
+ // man-page says about setuid(2)) but we cargo culted it anyway
+
+
+ if (seteuid(pw->pw_uid) != 0)
+ return _error->Errno("seteuid", "Failed to seteuid");
+
+ /* Try changing GID/EGID */
+ if (pw->pw_gid != old_gid && (setgid(old_gid) != -1 || setegid(old_gid) != -1))
+ return _error->Error("Could restore a gid to root, privilege dropping did not work");
+
+ if (pw->pw_uid != old_uid && (setuid(old_uid) != -1 || seteuid(old_uid) != -1))
+ return _error->Error("Could restore a uid to root, privilege dropping did not work");
+
+ /* Verify the list of supplementary groups is what we expected */
+ gid_t groups[1];
+ if (getgroups(1, groups) != 1)
+ return _error->Errno("getgroups", "Could not get new groups");
+ if (groups[0] != pw->pw_gid)
+ return _error->Error("Could not switch group");
+ /* Verify gid, egid, uid, and euid */
+ if (getgid() != pw->pw_gid)
+ return _error->Error("Could not switch group");
+ if (getegid() != pw->pw_gid)
+ return _error->Error("Could not switch effective group");
+ if (getuid() != pw->pw_uid)
+ return _error->Error("Could not switch user");
+ if (geteuid() != pw->pw_uid)
+ return _error->Error("Could not switch effective user");
+
+ /* TODO: Check saved uid/saved gid as well */
+ return true;
+}
projects / apt.git / blobdiff