support/namespace.h

   1 /* Entering namespaces for test case isolation.
   2    Copyright (C) 2016-2023 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #ifndef SUPPORT_NAMESPACE_H
  20 #define SUPPORT_NAMESPACE_H
  21
  22 #include <stdbool.h>
  23 #include <sys/cdefs.h>
  24
  25 __BEGIN_DECLS
  26
  27 /* Attempts to become root (or acquire root-like privileges), possibly
  28    with the help of user namespaces.  Return true if (restricted) root
  29    privileges could be attained in some way.  Print diagnostics to
  30    standard output.
  31
  32    Note that this function generally has to be called before a process
  33    becomes multi-threaded, otherwise it may fail with insufficient
  34    privileges on systems which would support this operation for
  35    single-threaded processes.  */
  36 bool support_become_root (void);
  37
  38 /* Return true if this process can perform a chroot operation.  In
  39    general, this is only possible if support_become_root has been
  40    called.  Note that the actual test is performed in a subprocess,
  41    after fork, so that the file system root of the original process is
  42    not changed.  */
  43 bool support_can_chroot (void);
  44
  45 /* Enter a network namespace (and a UTS namespace if possible) and
  46    configure the loopback interface.  Return true if a network
  47    namespace could be created.  Print diagnostics to standard output.
  48    If a network namespace could be created, but networking in it could
  49    not be configured, terminate the process.  It is recommended to
  50    call support_become_root before this function so that the process
  51    has sufficient privileges.  */
  52 bool support_enter_network_namespace (void);
  53
  54 /* Enter a mount namespace and mark / as private (not shared).  If
  55    this function returns true, mount operations in this process will
  56    not affect the host system afterwards.  */
  57 bool support_enter_mount_namespace (void);
  58
  59 /* Return true if support_enter_network_namespace managed to enter a
  60    UTS namespace.  */
  61 bool support_in_uts_namespace (void);
  62
  63 /* Invoke CALLBACK (CLOSURE) in a subprocess created using fork.
  64    Terminate the calling process if the subprocess exits with a
  65    non-zero exit status.  */
  66 void support_isolate_in_subprocess (void (*callback) (void *), void *closure);
  67
  68 /* Describe the setup of a chroot environment, for
  69    support_chroot_create below.  */
  70 struct support_chroot_configuration
  71 {
  72   /* File contents.  The files are not created if the field is
  73      NULL.  */
  74   const char *resolv_conf;      /* /etc/resolv.conf.  */
  75   const char *hosts;            /* /etc/hosts.  */
  76   const char *host_conf;        /* /etc/host.conf.  */
  77   const char *aliases;          /* /etc/aliases.  */
  78 };
  79
  80 /* The result of the creation of a chroot.  */
  81 struct support_chroot
  82 {
  83   /* Path information.  All these paths are relative to the parent
  84      chroot.  */
  85
  86   /* Path to the chroot directory.  */
  87   char *path_chroot;
  88
  89   /* Paths to files in the chroot.  These are absolute and outside of
  90      the chroot.  */
  91   char *path_resolv_conf;       /* /etc/resolv.conf.  */
  92   char *path_hosts;             /* /etc/hosts.  */
  93   char *path_host_conf;         /* /etc/host.conf.  */
  94   char *path_aliases;           /* /etc/aliases.  */
  95 };
  96
  97 /* Create a chroot environment.  The returned data should be freed
  98    using support_chroot_free below.  The files will be deleted when
  99    the process exits.  This function does not enter the chroot.  */
 100 struct support_chroot *support_chroot_create
 101   (struct support_chroot_configuration);
 102
 103 /* Deallocate the chroot information created by
 104    support_chroot_create.  */
 105 void support_chroot_free (struct support_chroot *);
 106
 107 __END_DECLS
 108
 109 #endif