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-rw-r--r--apt-pkg/contrib/fileutl.cc34
1 files changed, 33 insertions, 1 deletions
diff --git a/apt-pkg/contrib/fileutl.cc b/apt-pkg/contrib/fileutl.cc
index 6b8f04dea..de67a94b9 100644
--- a/apt-pkg/contrib/fileutl.cc
+++ b/apt-pkg/contrib/fileutl.cc
@@ -48,6 +48,7 @@
#include <errno.h>
#include <glob.h>
#include <pwd.h>
+#include <grp.h>
#include <set>
#include <algorithm>
@@ -64,6 +65,10 @@
#include <endian.h>
#include <stdint.h>
+#if __gnu_linux__
+#include <sys/prctl.h>
+#endif
+
#include <apti18n.h>
/*}}}*/
@@ -2173,14 +2178,41 @@ bool DropPrivs()
if (getuid() != 0)
return true;
- const std::string nobody = _config->Find("APT::User::Nobody", "nobody");
+ if(_config->FindB("Debug::NoDropPrivs", false) == true)
+ return true;
+
+ const std::string nobody = _config->Find("APT::User::Nobody", "Debian-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("setgid", "Failed to setgid");
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 (setuid(pw->pw_uid) != 0)
+ return _error->Errno("setuid", "Failed to setuid");
+
+ // be defensive
+ if(setgid(0) != -1 || setegid(0) != -1)
+ return _error->Error("Could restore gid to root, privilege dropping does not work");
+ if(setuid(0) != -1 || seteuid(0) != -1)
+ return _error->Error("Could restore uid to root, privilege dropping does not work");
return true;
}