linux/include/linux/securebits.h
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   1#ifndef _LINUX_SECUREBITS_H
   2#define _LINUX_SECUREBITS_H 1
   3
   4/* Each securesetting is implemented using two bits. One bit specifies
   5   whether the setting is on or off. The other bit specify whether the
   6   setting is locked or not. A setting which is locked cannot be
   7   changed from user-level. */
   8#define issecure_mask(X)        (1 << (X))
   9#ifdef __KERNEL__
  10#define issecure(X)             (issecure_mask(X) & current_cred_xxx(securebits))
  11#endif
  12
  13#define SECUREBITS_DEFAULT 0x00000000
  14
  15/* When set UID 0 has no special privileges. When unset, we support
  16   inheritance of root-permissions and suid-root executable under
  17   compatibility mode. We raise the effective and inheritable bitmasks
  18   *of the executable file* if the effective uid of the new process is
  19   0. If the real uid is 0, we raise the effective (legacy) bit of the
  20   executable file. */
  21#define SECURE_NOROOT                   0
  22#define SECURE_NOROOT_LOCKED            1  /* make bit-0 immutable */
  23
  24#define SECBIT_NOROOT           (issecure_mask(SECURE_NOROOT))
  25#define SECBIT_NOROOT_LOCKED    (issecure_mask(SECURE_NOROOT_LOCKED))
  26
  27/* When set, setuid to/from uid 0 does not trigger capability-"fixup".
  28   When unset, to provide compatiblility with old programs relying on
  29   set*uid to gain/lose privilege, transitions to/from uid 0 cause
  30   capabilities to be gained/lost. */
  31#define SECURE_NO_SETUID_FIXUP          2
  32#define SECURE_NO_SETUID_FIXUP_LOCKED   3  /* make bit-2 immutable */
  33
  34#define SECBIT_NO_SETUID_FIXUP  (issecure_mask(SECURE_NO_SETUID_FIXUP))
  35#define SECBIT_NO_SETUID_FIXUP_LOCKED \
  36                        (issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED))
  37
  38/* When set, a process can retain its capabilities even after
  39   transitioning to a non-root user (the set-uid fixup suppressed by
  40   bit 2). Bit-4 is cleared when a process calls exec(); setting both
  41   bit 4 and 5 will create a barrier through exec that no exec()'d
  42   child can use this feature again. */
  43#define SECURE_KEEP_CAPS                4
  44#define SECURE_KEEP_CAPS_LOCKED         5  /* make bit-4 immutable */
  45
  46#define SECBIT_KEEP_CAPS        (issecure_mask(SECURE_KEEP_CAPS))
  47#define SECBIT_KEEP_CAPS_LOCKED (issecure_mask(SECURE_KEEP_CAPS_LOCKED))
  48
  49#define SECURE_ALL_BITS         (issecure_mask(SECURE_NOROOT) | \
  50                                 issecure_mask(SECURE_NO_SETUID_FIXUP) | \
  51                                 issecure_mask(SECURE_KEEP_CAPS))
  52#define SECURE_ALL_LOCKS        (SECURE_ALL_BITS << 1)
  53
  54#endif /* !_LINUX_SECUREBITS_H */
  55
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