diff options
Diffstat (limited to 'apt-pkg/contrib/fileutl.cc')
| -rw-r--r-- | apt-pkg/contrib/fileutl.cc | 102 |
1 files changed, 60 insertions, 42 deletions
diff --git a/apt-pkg/contrib/fileutl.cc b/apt-pkg/contrib/fileutl.cc index f754b313e..014f0ee51 100644 --- a/apt-pkg/contrib/fileutl.cc +++ b/apt-pkg/contrib/fileutl.cc @@ -2283,6 +2283,12 @@ bool DropPrivileges() /*{{{*/ if (toUser.empty() || toUser == "root") return true; + // a lot can go wrong trying to drop privileges completely, + // so ideally we would like to verify that we have done it – + // but the verify asks for too much in case of fakeroot (and alike) + // [Specific checks can be overridden with dedicated options] + bool const VerifySandboxing = _config->FindB("APT::Sandbox::Verify", false); + // 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(); @@ -2322,56 +2328,68 @@ bool DropPrivileges() /*{{{*/ return _error->Errno("seteuid", "Failed to seteuid"); #endif - // Verify that the user isn't still in any supplementary groups - long const ngroups_max = sysconf(_SC_NGROUPS_MAX); - std::unique_ptr<gid_t[]> gidlist(new gid_t[ngroups_max]); - if (unlikely(gidlist == NULL)) - return _error->Error("Allocation of a list of size %lu for getgroups failed", ngroups_max); - ssize_t gidlist_nr; - if ((gidlist_nr = getgroups(ngroups_max, gidlist.get())) < 0) - return _error->Errno("getgroups", "Could not get new groups (%lu)", ngroups_max); - for (ssize_t i = 0; i < gidlist_nr; ++i) - if (gidlist[i] != pw->pw_gid) - return _error->Error("Could not switch group, user %s is still in group %d", toUser.c_str(), gidlist[i]); - - // 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) - 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"); + // disabled by default as fakeroot doesn't implement getgroups currently (#806521) + if (VerifySandboxing == true || _config->FindB("APT::Sandbox::Verify::Groups", false) == true) + { + // Verify that the user isn't still in any supplementary groups + long const ngroups_max = sysconf(_SC_NGROUPS_MAX); + std::unique_ptr<gid_t[]> gidlist(new gid_t[ngroups_max]); + if (unlikely(gidlist == NULL)) + return _error->Error("Allocation of a list of size %lu for getgroups failed", ngroups_max); + ssize_t gidlist_nr; + if ((gidlist_nr = getgroups(ngroups_max, gidlist.get())) < 0) + return _error->Errno("getgroups", "Could not get new groups (%lu)", ngroups_max); + for (ssize_t i = 0; i < gidlist_nr; ++i) + if (gidlist[i] != pw->pw_gid) + return _error->Error("Could not switch group, user %s is still in group %d", toUser.c_str(), gidlist[i]); + } + + // enabled by default as all fakeroot-lookalikes should fake that accordingly + if (VerifySandboxing == true || _config->FindB("APT::Sandbox::Verify::IDs", true) == true) + { + // 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) + 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"); #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; - if (getresuid(&ruid, &euid, &suid)) - return _error->Errno("getresuid", "Could not get saved set-user-ID"); - if (suid != pw->pw_uid) - return _error->Error("Could not switch saved set-user-ID"); + // verify that the saved set-user-id was changed as well + uid_t ruid = 0; + uid_t euid = 0; + uid_t suid = 0; + if (getresuid(&ruid, &euid, &suid)) + return _error->Errno("getresuid", "Could not get saved set-user-ID"); + if (suid != pw->pw_uid) + return _error->Error("Could not switch saved set-user-ID"); #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; - if (getresgid(&rgid, &egid, &sgid)) - return _error->Errno("getresuid", "Could not get saved set-group-ID"); - if (sgid != pw->pw_gid) - return _error->Error("Could not switch saved set-group-ID"); + // verify that the saved set-group-id was changed as well + gid_t rgid = 0; + gid_t egid = 0; + gid_t sgid = 0; + if (getresgid(&rgid, &egid, &sgid)) + return _error->Errno("getresuid", "Could not get saved set-group-ID"); + if (sgid != pw->pw_gid) + return _error->Error("Could not switch saved set-group-ID"); #endif + } - // 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"); + // disabled as fakeroot doesn't forbid (by design) (re)gaining root from unprivileged + if (VerifySandboxing == true || _config->FindB("APT::Sandbox::Verify::Regain", false) == true) + { + // 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"); + 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; } |