github.com/apptainer/singularity@v3.1.1+incompatible/cmd/starter/c/include/securebits.h (about)

     1  #ifndef _LINUX_SECUREBITS_H
     2  #define _LINUX_SECUREBITS_H
     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  
    10  #define SECUREBITS_DEFAULT 0x00000000
    11  
    12  /* When set UID 0 has no special privileges. When unset, we support
    13     inheritance of root-permissions and suid-root executable under
    14     compatibility mode. We raise the effective and inheritable bitmasks
    15     *of the executable file* if the effective uid of the new process is
    16     0. If the real uid is 0, we raise the effective (legacy) bit of the
    17     executable file. */
    18  #define SECURE_NOROOT           0
    19  #define SECURE_NOROOT_LOCKED    1  /* make bit-0 immutable */
    20  
    21  #define SECBIT_NOROOT           (issecure_mask(SECURE_NOROOT))
    22  #define SECBIT_NOROOT_LOCKED    (issecure_mask(SECURE_NOROOT_LOCKED))
    23  
    24  /* When set, setuid to/from uid 0 does not trigger capability-"fixup".
    25     When unset, to provide compatiblility with old programs relying on
    26     set*uid to gain/lose privilege, transitions to/from uid 0 cause
    27     capabilities to be gained/lost. */
    28  #define SECURE_NO_SETUID_FIXUP          2
    29  #define SECURE_NO_SETUID_FIXUP_LOCKED   3  /* make bit-2 immutable */
    30  
    31  #define SECBIT_NO_SETUID_FIXUP      (issecure_mask(SECURE_NO_SETUID_FIXUP))
    32  #define SECBIT_NO_SETUID_FIXUP_LOCKED \
    33  			(issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED))
    34  
    35  /* When set, a process can retain its capabilities even after
    36     transitioning to a non-root user (the set-uid fixup suppressed by
    37     bit 2). Bit-4 is cleared when a process calls exec(); setting both
    38     bit 4 and 5 will create a barrier through exec that no exec()'d
    39     child can use this feature again. */
    40  #define SECURE_KEEP_CAPS            4
    41  #define SECURE_KEEP_CAPS_LOCKED     5  /* make bit-4 immutable */
    42  
    43  #define SECBIT_KEEP_CAPS        (issecure_mask(SECURE_KEEP_CAPS))
    44  #define SECBIT_KEEP_CAPS_LOCKED (issecure_mask(SECURE_KEEP_CAPS_LOCKED))
    45  
    46  /* When set, a process cannot add new capabilities to its ambient set. */
    47  #define SECURE_NO_CAP_AMBIENT_RAISE         6
    48  #define SECURE_NO_CAP_AMBIENT_RAISE_LOCKED  7  /* make bit-6 immutable */
    49  
    50  #define SECBIT_NO_CAP_AMBIENT_RAISE (issecure_mask(SECURE_NO_CAP_AMBIENT_RAISE))
    51  #define SECBIT_NO_CAP_AMBIENT_RAISE_LOCKED \
    52              (issecure_mask(SECURE_NO_CAP_AMBIENT_RAISE_LOCKED))
    53  
    54  #ifdef USER_CAPABILITIES
    55  
    56  #  define SECURE_ALL_BITS   (issecure_mask(SECURE_NOROOT) | \
    57                               issecure_mask(SECURE_NO_SETUID_FIXUP) | \
    58                               issecure_mask(SECURE_KEEP_CAPS) | \
    59                               issecure_mask(SECURE_NO_CAP_AMBIENT_RAISE))
    60  
    61  #else
    62  
    63  #  define SECURE_ALL_BITS   (issecure_mask(SECURE_NOROOT) | \
    64                               issecure_mask(SECURE_NO_SETUID_FIXUP) | \
    65                               issecure_mask(SECURE_KEEP_CAPS))
    66  
    67  #endif /* USER_CAPABILITIES */
    68  
    69  #  define SECURE_ALL_LOCKS  (SECURE_ALL_BITS << 1)
    70  
    71  #endif /* _LINUX_SECUREBITS_H */