libbb/capability.c

   1 /*
   2  * Copyright (C) 2017 by  <assafgordon@gmail.com>
   3  *
   4  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   5  */
   6 //kbuild:lib-$(CONFIG_FEATURE_SETPRIV_CAPABILITIES) += capability.o
   7 //kbuild:lib-$(CONFIG_RUN_INIT) += capability.o
   8
   9 #include <linux/capability.h>
  10 // #include <sys/capability.h>
  11 // This header is in libcap, but the functions are in libc.
  12 // Comment in the header says this above capset/capget:
  13 /* system calls - look to libc for function to system call mapping */
  14 extern int capset(cap_user_header_t header, cap_user_data_t data);
  15 extern int capget(cap_user_header_t header, const cap_user_data_t data);
  16 // so for bbox, let's just repeat the declarations.
  17 // This way, libcap needs not be installed in build environment.
  18 #include "libbb.h"
  19
  20 static const char *const capabilities[] = {
  21         "chown",
  22         "dac_override",
  23         "dac_read_search",
  24         "fowner",
  25         "fsetid",
  26         "kill",
  27         "setgid",
  28         "setuid",
  29         "setpcap",
  30         "linux_immutable",
  31         "net_bind_service",
  32         "net_broadcast",
  33         "net_admin",
  34         "net_raw",
  35         "ipc_lock",
  36         "ipc_owner",
  37         "sys_module",
  38         "sys_rawio",
  39         "sys_chroot",
  40         "sys_ptrace",
  41         "sys_pacct",
  42         "sys_admin",
  43         "sys_boot",
  44         "sys_nice",
  45         "sys_resource",
  46         "sys_time",
  47         "sys_tty_config",
  48         "mknod",
  49         "lease",
  50         "audit_write",
  51         "audit_control",
  52         "setfcap",
  53         "mac_override",
  54         "mac_admin",
  55         "syslog",
  56         "wake_alarm",
  57         "block_suspend",
  58         "audit_read",
  59 };
  60
  61 unsigned FAST_FUNC cap_name_to_number(const char *cap)
  62 {
  63         unsigned i, n;
  64
  65         if ((sscanf(cap, "cap_%u", &n)) == 1) {
  66                 i = n;
  67                 goto found;
  68         }
  69         for (i = 0; i < ARRAY_SIZE(capabilities); i++) {
  70                 if (strcasecmp(capabilities[i], cap) == 0)
  71                         goto found;
  72         }
  73         bb_error_msg_and_die("unknown capability '%s'", cap);
  74
  75  found:
  76         if (!cap_valid(i))
  77                 bb_error_msg_and_die("unknown capability '%s'", cap);
  78         return i;
  79 }
  80
  81 void FAST_FUNC printf_cap(const char *pfx, unsigned cap_no)
  82 {
  83         if (cap_no < ARRAY_SIZE(capabilities)) {
  84                 printf("%s%s", pfx, capabilities[cap_no]);
  85                 return;
  86         }
  87         printf("%scap_%u", pfx, cap_no);
  88 }
  89
  90 DEFINE_STRUCT_CAPS;
  91
  92 void FAST_FUNC getcaps(void *arg)
  93 {
  94         static const uint8_t versions[] = {
  95                 _LINUX_CAPABILITY_U32S_3, /* = 2 (fits into byte) */
  96                 _LINUX_CAPABILITY_U32S_2, /* = 2 */
  97                 _LINUX_CAPABILITY_U32S_1, /* = 1 */
  98         };
  99         int i;
 100         struct caps *caps = arg;
 101
 102         caps->header.pid = 0;
 103         for (i = 0; i < ARRAY_SIZE(versions); i++) {
 104                 caps->header.version = versions[i];
 105                 if (capget(&caps->header, NULL) == 0)
 106                         goto got_it;
 107         }
 108         bb_simple_perror_msg_and_die("capget");
 109  got_it:
 110
 111         switch (caps->header.version) {
 112                 case _LINUX_CAPABILITY_VERSION_1:
 113                         caps->u32s = _LINUX_CAPABILITY_U32S_1;
 114                         break;
 115                 case _LINUX_CAPABILITY_VERSION_2:
 116                         caps->u32s = _LINUX_CAPABILITY_U32S_2;
 117                         break;
 118                 case _LINUX_CAPABILITY_VERSION_3:
 119                         caps->u32s = _LINUX_CAPABILITY_U32S_3;
 120                         break;
 121                 default:
 122                         bb_simple_error_msg_and_die("unsupported capability version");
 123         }
 124
 125         if (capget(&caps->header, caps->data) != 0)
 126                 bb_simple_perror_msg_and_die("capget");
 127 }