1 files changed, 147 insertions, 0 deletions
diff --git a/src/daemon/caps.c b/src/daemon/caps.c
new file mode 100644
index 00000000..ae07119c
--- /dev/null
+++ b/src/daemon/caps.c
@@ -0,0 +1,147 @@
+/***
+  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 */
+void pa_limit_caps(void) {
+    cap_t caps;
+    cap_value_t nice_cap = CAP_SYS_NICE;
+
+    pa_assert_se(caps = cap_init());
+    pa_assert_se(cap_clear(caps) == 0);
+    pa_assert_se(cap_set_flag(caps, CAP_EFFECTIVE, 1, &nice_cap, CAP_SET) == 0);
+    pa_assert_se(cap_set_flag(caps, CAP_PERMITTED, 1, &nice_cap, CAP_SET) == 0);
+
+    if (cap_set_proc(caps) < 0)
+        /* Hmm, so we couldn't limit our caps, which probably means we
+         * hadn't any in the first place, so let's just make sure of
+         * that */
+        pa_drop_caps();
+    else
+        pa_log_info("Limited capabilities successfully to CAP_SYS_NICE.");
+
+    pa_assert_se(cap_free(caps) == 0);
+
+    pa_assert_se(prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) == 0);
+}
+
+/* Drop all capabilities, effectively becoming a normal user */
+void pa_drop_caps(void) {
+    cap_t caps;
+
+    pa_assert_se(prctl(PR_SET_KEEPCAPS, 0, 0, 0, 0) == 0);
+
+    pa_assert_se(caps = cap_init());
+    pa_assert_se(cap_clear(caps) == 0);
+    pa_assert_se(cap_set_proc(caps) == 0);
+    pa_assert_se(cap_free(caps) == 0);
+
+    pa_assert_se(!pa_have_caps());
+}
+
+pa_bool_t pa_have_caps(void) {
+    cap_t caps;
+    cap_flag_value_t flag = CAP_CLEAR;
+
+    pa_assert_se(caps = cap_get_proc());
+    pa_assert_se(cap_get_flag(caps, CAP_SYS_NICE, CAP_EFFECTIVE, &flag) >= 0);
+    pa_assert_se(cap_free(caps) == 0);
+
+    return flag == CAP_SET;
+}
+
+#else
+
+/* NOOPs in case capabilities are not available. */
+void pa_limit_caps(void) {
+}
+
+void pa_drop_caps(void) {
+    pa_drop_root();
+}
+
+pa_bool_t pa_have_caps(void) {
+    return FALSE;
+}
+
+#endif