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