X-Git-Url: https://git.saurik.com/apt.git/blobdiff_plain/550ab420d398f303ff8cbc51e1f4dab79f8cbdf2..e8afd16892e87a6e2f17c1019ee455f5583387c2:/apt-pkg/contrib/fileutl.cc diff --git a/apt-pkg/contrib/fileutl.cc b/apt-pkg/contrib/fileutl.cc index 05c2f2e00..8ec868ec0 100644 --- a/apt-pkg/contrib/fileutl.cc +++ b/apt-pkg/contrib/fileutl.cc @@ -800,8 +800,9 @@ pid_t ExecFork(std::set KeepFDs) signal(SIGCONT,SIG_DFL); signal(SIGTSTP,SIG_DFL); + long ScOpenMax = sysconf(_SC_OPEN_MAX); // Close all of our FDs - just in case - for (int K = 3; K != sysconf(_SC_OPEN_MAX); K++) + for (int K = 3; K != ScOpenMax; K++) { if(KeepFDs.find(K) == KeepFDs.end()) fcntl(K,F_SETFD,FD_CLOEXEC); @@ -857,11 +858,7 @@ bool ExecWait(pid_t Pid,const char *Name,bool Reap) return true; } /*}}}*/ - - -// StartsWithGPGClearTextSignature - Check if a file is Pgp/GPG clearsigned /*{{{*/ -// --------------------------------------------------------------------- -/* */ +// StartsWithGPGClearTextSignature - Check if a file is Pgp/GPG clearsigned /*{{{*/ bool StartsWithGPGClearTextSignature(string const &FileName) { static const char* SIGMSG = "-----BEGIN PGP SIGNED MESSAGE-----\n"; @@ -877,7 +874,26 @@ bool StartsWithGPGClearTextSignature(string const &FileName) return true; } - + /*}}}*/ +// ChangeOwnerAndPermissionOfFile - set file attributes to requested values /*{{{*/ +bool ChangeOwnerAndPermissionOfFile(char const * const requester, char const * const file, char const * const user, char const * const group, mode_t const mode) +{ + if (strcmp(file, "/dev/null") == 0) + return true; + bool Res = true; + if (getuid() == 0 && strlen(user) != 0 && strlen(group) != 0) // if we aren't root, we can't chown, so don't try it + { + // ensure the file is owned by root and has good permissions + struct passwd const * const pw = getpwnam(user); + struct group const * const gr = getgrnam(group); + if (pw != NULL && gr != NULL && chown(file, pw->pw_uid, gr->gr_gid) != 0) + Res &= _error->WarningE(requester, "chown to %s:%s of file %s failed", user, group, file); + } + if (chmod(file, mode) != 0) + Res &= _error->WarningE(requester, "chmod 0%o of file %s failed", mode, file); + return Res; +} + /*}}}*/ class FileFdPrivate { /*{{{*/ public: @@ -896,7 +912,7 @@ class FileFdPrivate { /*{{{*/ bool eof; bool compressing; - LZMAFILE() : file(NULL), eof(false), compressing(false) {} + LZMAFILE() : file(NULL), eof(false), compressing(false) { buffer[0] = '\0'; } ~LZMAFILE() { if (compressing == true) { @@ -1525,7 +1541,7 @@ bool FileFd::Read(void *To,unsigned long long Size,unsigned long long *Actual) int err; char const * const errmsg = BZ2_bzerror(d->bz2, &err); if (err != BZ_IO_ERROR) - return FileFdError("BZ2_bzread: %s (%d: %s)", _("Read error"), err, errmsg); + return FileFdError("BZ2_bzread: %s %s (%d: %s)", FileName.c_str(), _("Read error"), err, errmsg); } #endif #ifdef HAVE_LZMA @@ -2035,10 +2051,7 @@ APT_DEPRECATED gzFile FileFd::gzFd() { #endif } - -// Glob - wrapper around "glob()" /*{{{*/ -// --------------------------------------------------------------------- -/* */ +// Glob - wrapper around "glob()" /*{{{*/ std::vector Glob(std::string const &pattern, int flags) { std::vector result; @@ -2064,8 +2077,7 @@ std::vector Glob(std::string const &pattern, int flags) return result; } /*}}}*/ - -std::string GetTempDir() +std::string GetTempDir() /*{{{*/ { const char *tmpdir = getenv("TMPDIR"); @@ -2074,15 +2086,17 @@ std::string GetTempDir() tmpdir = P_tmpdir; #endif - // check that tmpdir is set and exists struct stat st; - if (!tmpdir || strlen(tmpdir) == 0 || stat(tmpdir, &st) != 0) + if (!tmpdir || strlen(tmpdir) == 0 || // tmpdir is set + stat(tmpdir, &st) != 0 || (st.st_mode & S_IFDIR) == 0 || // exists and is directory + access(tmpdir, R_OK | W_OK | X_OK) != 0 // current user has rwx access to directory + ) tmpdir = "/tmp"; return string(tmpdir); } - -FileFd* GetTempFile(std::string const &Prefix, bool ImmediateUnlink) + /*}}}*/ +FileFd* GetTempFile(std::string const &Prefix, bool ImmediateUnlink) /*{{{*/ { char fn[512]; FileFd *Fd = new FileFd(); @@ -2106,19 +2120,19 @@ FileFd* GetTempFile(std::string const &Prefix, bool ImmediateUnlink) return Fd; } - -bool Rename(std::string From, std::string To) + /*}}}*/ +bool Rename(std::string From, std::string To) /*{{{*/ { if (rename(From.c_str(),To.c_str()) != 0) { _error->Error(_("rename failed, %s (%s -> %s)."),strerror(errno), From.c_str(),To.c_str()); return false; - } + } return true; } - -bool Popen(const char* Args[], FileFd &Fd, pid_t &Child, FileFd::OpenMode Mode) + /*}}}*/ +bool Popen(const char* Args[], FileFd &Fd, pid_t &Child, FileFd::OpenMode Mode)/*{{{*/ { int fd; if (Mode != FileFd::ReadOnly && Mode != FileFd::WriteOnly) @@ -2126,10 +2140,8 @@ bool Popen(const char* Args[], FileFd &Fd, pid_t &Child, FileFd::OpenMode Mode) int Pipe[2] = {-1, -1}; if(pipe(Pipe) != 0) - { return _error->Errno("pipe", _("Failed to create subprocess IPC")); - return NULL; - } + std::set keep_fds; keep_fds.insert(Pipe[0]); keep_fds.insert(Pipe[1]); @@ -2172,30 +2184,41 @@ bool Popen(const char* Args[], FileFd &Fd, pid_t &Child, FileFd::OpenMode Mode) return true; } - -bool DropPrivs() + /*}}}*/ +bool DropPrivileges() /*{{{*/ { - /* 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) +#if defined(PR_SET_NO_NEW_PRIVS) && ( PR_SET_NO_NEW_PRIVS != 38 ) +#error "PR_SET_NO_NEW_PRIVS is defined, but with a different value than expected!" +#endif + // see prctl(2), needs linux3.5 at runtime - magic constant to avoid it at buildtime + int ret = prctl(38, 1, 0, 0, 0); + // ignore EINVAL - kernel is too old to understand the option + if(ret < 0 && errno != EINVAL) _error->Warning("PR_SET_NO_NEW_PRIVS failed with %i", ret); #endif + // empty setting disables privilege dropping - this also ensures + // backward compatibility, see bug #764506 + const std::string toUser = _config->Find("APT::Sandbox::User"); + if (toUser.empty()) + return true; + + // uid will be 0 in the end, but gid might be different anyway + uid_t const old_uid = getuid(); + gid_t const old_gid = getgid(); + + if (old_uid != 0) + return true; + + struct passwd *pw = getpwnam(toUser.c_str()); + if (pw == NULL) + return _error->Error("No user %s, can not drop rights", toUser.c_str()); + + // Do not change the order here, it might break things if (setgroups(1, &pw->pw_gid)) return _error->Errno("setgroups", "Failed to setgroups"); @@ -2207,27 +2230,20 @@ bool DropPrivs() 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 */ + // Verify that the user has only a single group, and the correct one 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 */ + + // Verify that gid, egid, uid, and euid changed if (getgid() != pw->pw_gid) return _error->Error("Could not switch group"); if (getegid() != pw->pw_gid) @@ -2238,6 +2254,7 @@ bool DropPrivs() return _error->Error("Could not switch effective user"); #ifdef HAVE_GETRESUID + // verify that the saved set-user-id was changed as well uid_t ruid = 0; uid_t euid = 0; uid_t suid = 0; @@ -2248,6 +2265,7 @@ bool DropPrivs() #endif #ifdef HAVE_GETRESGID + // verify that the saved set-group-id was changed as well gid_t rgid = 0; gid_t egid = 0; gid_t sgid = 0; @@ -2257,6 +2275,13 @@ bool DropPrivs() return _error->Error("Could not switch saved set-group-ID"); #endif - /* TODO: Check saved uid/saved gid as well */ + // Check that uid and gid changes do not work anymore + 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"); + return true; } + /*}}}*/