1 files changed, 88 insertions, 0 deletions
diff --git a/src/basic/capability-util.h b/src/basic/capability-util.h
new file mode 100644
index 0000000..f911de8
--- /dev/null
+++ b/src/basic/capability-util.h
@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <sys/capability.h>
+#include <sys/types.h>
+
+#include "macro.h"
+#include "missing_capability.h"
+
+/* Special marker used when storing a capabilities mask as "unset" */
+#define CAP_MASK_UNSET UINT64_MAX
+
+/* All possible capabilities bits on */
+#define CAP_MASK_ALL UINT64_C(0x7fffffffffffffff)
+
+/* The largest capability we can deal with, given we want to be able to store cap masks in uint64_t but still
+ * be able to use UINT64_MAX as indicator for "not set". The latter makes capability 63 unavailable. */
+#define CAP_LIMIT 62
+
+unsigned cap_last_cap(void);
+int have_effective_cap(int value);
+int capability_gain_cap_setpcap(cap_t *return_caps);
+int capability_bounding_set_drop(uint64_t keep, bool right_now);
+int capability_bounding_set_drop_usermode(uint64_t keep);
+
+int capability_ambient_set_apply(uint64_t set, bool also_inherit);
+int capability_update_inherited_set(cap_t caps, uint64_t ambient_set);
+
+int drop_privileges(uid_t uid, gid_t gid, uint64_t keep_capabilities);
+
+int drop_capability(cap_value_t cv);
+int keep_capability(cap_value_t cv);
+
+DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(cap_t, cap_free, NULL);
+#define _cleanup_cap_free_ _cleanup_(cap_freep)
+
+static inline void cap_free_charpp(char **p) {
+        if (*p)
+                cap_free(*p);
+}
+#define _cleanup_cap_free_charp_ _cleanup_(cap_free_charpp)
+
+static inline uint64_t all_capabilities(void) {
+        return UINT64_MAX >> (63 - cap_last_cap());
+}
+
+static inline bool cap_test_all(uint64_t caps) {
+        return FLAGS_SET(caps, all_capabilities());
+}
+
+bool ambient_capabilities_supported(void);
+
+/* Identical to linux/capability.h's CAP_TO_MASK(), but uses an unsigned 1U instead of a signed 1 for shifting left, in
+ * order to avoid complaints about shifting a signed int left by 31 bits, which would make it negative. */
+#define CAP_TO_MASK_CORRECTED(x) (1U << ((x) & 31U))
+
+typedef struct CapabilityQuintet {
+        /* Stores all five types of capabilities in one go. Note that we use UINT64_MAX for unset here. This hence
+         * needs to be updated as soon as Linux learns more than 63 caps. */
+        uint64_t effective;
+        uint64_t bounding;
+        uint64_t inheritable;
+        uint64_t permitted;
+        uint64_t ambient;
+} CapabilityQuintet;
+
+assert_cc(CAP_LAST_CAP < 64);
+
+#define CAPABILITY_QUINTET_NULL { CAP_MASK_UNSET, CAP_MASK_UNSET, CAP_MASK_UNSET, CAP_MASK_UNSET, CAP_MASK_UNSET }
+
+static inline bool capability_quintet_is_set(const CapabilityQuintet *q) {
+        return q->effective != CAP_MASK_UNSET ||
+                q->bounding != CAP_MASK_UNSET ||
+                q->inheritable != CAP_MASK_UNSET ||
+                q->permitted != CAP_MASK_UNSET ||
+                q->ambient != CAP_MASK_UNSET;
+}
+
+/* Mangles the specified caps quintet taking the current bounding set into account:
+ * drops all caps from all five sets if our bounding set doesn't allow them.
+ * Returns true if the quintet was modified. */
+bool capability_quintet_mangle(CapabilityQuintet *q);
+
+int capability_quintet_enforce(const CapabilityQuintet *q);
+
+int capability_get_ambient(uint64_t *ret);