src/basic/capability-util.h

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 #pragma once
   3
   4 #include <stdbool.h>
   5 #include <stdint.h>
   6 #include <sys/capability.h>
   7 #include <sys/types.h>
   8
   9 #include "macro.h"
  10 #include "missing_capability.h"
  11 #include "util.h"
  12
  13 #define CAP_ALL (uint64_t) -1
  14
  15 unsigned cap_last_cap(void);
  16 int have_effective_cap(int value);
  17 int capability_bounding_set_drop(uint64_t keep, bool right_now);
  18 int capability_bounding_set_drop_usermode(uint64_t keep);
  19
  20 int capability_ambient_set_apply(uint64_t set, bool also_inherit);
  21 int capability_update_inherited_set(cap_t caps, uint64_t ambient_set);
  22
  23 int drop_privileges(uid_t uid, gid_t gid, uint64_t keep_capabilities);
  24
  25 int drop_capability(cap_value_t cv);
  26
  27 DEFINE_TRIVIAL_CLEANUP_FUNC(cap_t, cap_free);
  28 #define _cleanup_cap_free_ _cleanup_(cap_freep)
  29
  30 static inline void cap_free_charpp(char **p) {
  31         if (*p)
  32                 cap_free(*p);
  33 }
  34 #define _cleanup_cap_free_charp_ _cleanup_(cap_free_charpp)
  35
  36 static inline uint64_t all_capabilities(void) {
  37         return UINT64_MAX >> (63 - cap_last_cap());
  38 }
  39
  40 static inline bool cap_test_all(uint64_t caps) {
  41         return FLAGS_SET(caps, all_capabilities());
  42 }
  43
  44 bool ambient_capabilities_supported(void);
  45
  46 /* Identical to linux/capability.h's CAP_TO_MASK(), but uses an unsigned 1U instead of a signed 1 for shifting left, in
  47  * order to avoid complaints about shifting a signed int left by 31 bits, which would make it negative. */
  48 #define CAP_TO_MASK_CORRECTED(x) (1U << ((x) & 31U))
  49
  50 typedef struct CapabilityQuintet {
  51         /* Stores all five types of capabilities in one go. Note that we use (uint64_t) -1 for unset here. This hence
  52          * needs to be updated as soon as Linux learns more than 63 caps. */
  53         uint64_t effective;
  54         uint64_t bounding;
  55         uint64_t inheritable;
  56         uint64_t permitted;
  57         uint64_t ambient;
  58 } CapabilityQuintet;
  59
  60 assert_cc(CAP_LAST_CAP < 64);
  61
  62 #define CAPABILITY_QUINTET_NULL { (uint64_t) -1, (uint64_t) -1, (uint64_t) -1, (uint64_t) -1, (uint64_t) -1 }
  63
  64 static inline bool capability_quintet_is_set(const CapabilityQuintet *q) {
  65         return q->effective != (uint64_t) -1 ||
  66                 q->bounding != (uint64_t) -1 ||
  67                 q->inheritable != (uint64_t) -1 ||
  68                 q->permitted != (uint64_t) -1 ||
  69                 q->ambient != (uint64_t) -1;
  70 }
  71
  72 /* Mangles the specified caps quintet taking the current bounding set into account:
  73  * drops all caps from all five sets if our bounding set doesn't allow them.
  74  * Returns true if the quintet was modified. */
  75 bool capability_quintet_mangle(CapabilityQuintet *q);
  76
  77 int capability_quintet_enforce(const CapabilityQuintet *q);