1 files changed, 152 insertions, 0 deletions
diff --git a/src/daemon/caps.c b/src/daemon/caps.c
new file mode 100644
index 00000000..44ee355e
--- /dev/null
+++ b/src/daemon/caps.c
@@ -0,0 +1,152 @@
+/* $Id$ */
+
+/***
+  This file is part of PulseAudio.
+
+  Copyright 2004-2006 Lennart Poettering
+  Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB
+
+  PulseAudio is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License as published
+  by the Free Software Foundation; either version 2 of the License,
+  or (at your option) any later version.
+
+  PulseAudio is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with PulseAudio; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+  USA.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/types.h>
+#include <pulsecore/macro.h>
+
+#ifdef HAVE_SYS_CAPABILITY_H
+#include <sys/capability.h>
+#endif
+#ifdef HAVE_SYS_PRCTL_H
+#include <sys/prctl.h>
+#endif
+
+#include <pulsecore/core-error.h>
+
+#include <pulsecore/log.h>
+
+#include "caps.h"
+
+/* Glibc <= 2.2 has broken unistd.h */
+#if defined(linux) && (__GLIBC__ <= 2 && __GLIBC_MINOR__ <= 2)
+int setresgid(gid_t r, gid_t e, gid_t s);
+int setresuid(uid_t r, uid_t e, uid_t s);
+#endif
+
+#ifdef HAVE_GETUID
+
+/* Drop root rights when called SUID root */
+void pa_drop_root(void) {
+    uid_t uid = getuid();
+
+    if (uid == 0 || geteuid() != 0)
+        return;
+
+    pa_log_info("Dropping root priviliges.");
+
+#if defined(HAVE_SETRESUID)
+    pa_assert_se(setresuid(uid, uid, uid) >= 0);
+#elif defined(HAVE_SETREUID)
+    pa_assert_se(setreuid(uid, uid) >= 0);
+#else
+    pa_assert_se(setuid(uid) >= 0);
+    pa_assert_se(seteuid(uid) >= 0);
+#endif
+
+    pa_assert_se(getuid() == uid);
+    pa_assert_se(geteuid() == uid);
+}
+
+#else
+
+void pa_drop_root(void) {
+}
+
+#endif
+
+#if defined(HAVE_SYS_CAPABILITY_H) && defined(HAVE_SYS_PRCTL_H)
+
+/* Limit permitted capabilities set to CAPSYS_NICE */
+int pa_limit_caps(void) {
+    int r = -1;
+    cap_t caps;
+    cap_value_t nice_cap = CAP_SYS_NICE;
+
+    caps = cap_init();
+    pa_assert(caps);
+    cap_clear(caps);
+    cap_set_flag(caps, CAP_EFFECTIVE, 1, &nice_cap, CAP_SET);
+    cap_set_flag(caps, CAP_PERMITTED, 1, &nice_cap, CAP_SET);
+
+    if (cap_set_proc(caps) < 0)
+        goto fail;
+
+    if (prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) < 0)
+        goto fail;
+
+    pa_log_info("Dropped capabilities successfully.");
+
+    r = 1;
+
+fail:
+    cap_free(caps);
+
+    return r;
+}
+
+/* Drop all capabilities, effectively becoming a normal user */
+int pa_drop_caps(void) {
+    cap_t caps;
+    int r = -1;
+
+    caps = cap_init();
+    pa_assert(caps);
+
+    cap_clear(caps);
+
+    prctl(PR_SET_KEEPCAPS, 0, 0, 0, 0);
+
+    if (cap_set_proc(caps) < 0) {
+        pa_log("Failed to drop capabilities: %s", pa_cstrerror(errno));
+        goto fail;
+    }
+
+    r = 0;
+
+fail:
+    cap_free(caps);
+
+    return r;
+}
+
+#else
+
+/* NOOPs in case capabilities are not available. */
+int pa_limit_caps(void) {
+    return 0;
+}
+
+int pa_drop_caps(void) {
+    pa_drop_root();
+    return 0;
+}
+
+#endif