utils/mountd/v4root.c

   1 /*
   2  * Copyright (C) 2009 Red Hat <nfs@redhat.com>
   3  *
   4  * support/export/v4root.c
   5  *
   6  * Routines used to support NFSv4 pseudo roots
   7  *
   8  */
   9
  10 #ifdef HAVE_CONFIG_H
  11 #include <config.h>
  12 #endif
  13
  14 #include <sys/types.h>
  15 #include <sys/stat.h>
  16 #include <sys/queue.h>
  17 #include <stdio.h>
  18 #include <stdlib.h>
  19 #include <ctype.h>
  20
  21 #include <unistd.h>
  22 #include <errno.h>
  23
  24 #include "xlog.h"
  25 #include "exportfs.h"
  26 #include "nfslib.h"
  27 #include "misc.h"
  28 #include "v4root.h"
  29
  30 int v4root_needed;
  31
  32 static nfs_export pseudo_root = {
  33         .m_next = NULL,
  34         .m_client = NULL,
  35         .m_export = {
  36                 .e_hostname = "*",
  37                 .e_path = "/",
  38                 .e_flags = NFSEXP_READONLY | NFSEXP_ROOTSQUASH
  39                                 | NFSEXP_NOSUBTREECHECK | NFSEXP_FSID
  40                                 | NFSEXP_V4ROOT,
  41                 .e_anonuid = 65534,
  42                 .e_anongid = 65534,
  43                 .e_squids = NULL,
  44                 .e_nsquids = 0,
  45                 .e_sqgids = NULL,
  46                 .e_nsqgids = 0,
  47                 .e_fsid = 0,
  48                 .e_mountpoint = NULL,
  49                 .e_ttl = DEFAULT_TTL,
  50         },
  51         .m_exported = 0,
  52         .m_xtabent = 1,
  53         .m_mayexport = 1,
  54         .m_changed = 0,
  55         .m_warned = 0,
  56 };
  57
  58 static void
  59 set_pseudofs_security(struct exportent *pseudo, struct exportent *source)
  60 {
  61         struct sec_entry *se;
  62         int i;
  63
  64         if (source->e_flags & NFSEXP_INSECURE_PORT)
  65                 pseudo->e_flags |= NFSEXP_INSECURE_PORT;
  66         if ((source->e_flags & NFSEXP_ROOTSQUASH) == 0)
  67                 pseudo->e_flags &= ~NFSEXP_ROOTSQUASH;
  68         for (se = source->e_secinfo; se->flav; se++) {
  69                 struct sec_entry *new;
  70
  71                 i = secinfo_addflavor(se->flav, pseudo);
  72                 new = &pseudo->e_secinfo[i];
  73
  74                 if (se->flags & NFSEXP_INSECURE_PORT)
  75                         new->flags |= NFSEXP_INSECURE_PORT;
  76         }
  77 }
  78
  79 /*
  80  * Create a pseudo export
  81  */
  82 static struct exportent *
  83 v4root_create(char *path, nfs_export *export)
  84 {
  85         nfs_export *exp;
  86         struct exportent eep;
  87         struct exportent *curexp = &export->m_export;
  88
  89         dupexportent(&eep, &pseudo_root.m_export);
  90         eep.e_hostname = curexp->e_hostname;
  91         strncpy(eep.e_path, path, sizeof(eep.e_path));
  92         if (strcmp(path, "/") != 0)
  93                 eep.e_flags &= ~NFSEXP_FSID;
  94         set_pseudofs_security(&eep, curexp);
  95         exp = export_create(&eep, 0);
  96         if (exp == NULL)
  97                 return NULL;
  98         xlog(D_CALL, "v4root_create: path '%s' flags 0x%x",
  99                 exp->m_export.e_path, exp->m_export.e_flags);
 100         return &exp->m_export;
 101 }
 102
 103 /*
 104  * Make sure the kernel has pseudo root support.
 105  */
 106 static int
 107 v4root_support(void)
 108 {
 109         struct export_features *ef;
 110         static int warned = 0;
 111
 112         ef = get_export_features();
 113
 114         if (ef->flags & NFSEXP_V4ROOT)
 115                 return 1;
 116         if (!warned) {
 117                 xlog(L_WARNING, "Kernel does not have pseudo root support.");
 118                 xlog(L_WARNING, "NFS v4 mounts will be disabled unless fsid=0");
 119                 xlog(L_WARNING, "is specfied in /etc/exports file.");
 120                 warned++;
 121         }
 122         return 0;
 123 }
 124
 125 static int
 126 pseudofs_update(char *hostname, char *path, nfs_export *source)
 127 {
 128         nfs_export *exp;
 129
 130         exp = export_lookup(hostname, path, 0);
 131         if (exp && !(exp->m_export.e_flags & NFSEXP_V4ROOT))
 132                 return 0;
 133         if (!exp) {
 134                 if (v4root_create(path, source) == NULL) {
 135                         xlog(L_WARNING, "v4root_set: Unable to create "
 136                                         "pseudo export for '%s'", path);
 137                         return -ENOMEM;
 138                 }
 139                 return 0;
 140         }
 141         /* Update an existing V4ROOT export: */
 142         set_pseudofs_security(&exp->m_export, &source->m_export);
 143         return 0;
 144 }
 145
 146 static int v4root_add_parents(nfs_export *exp)
 147 {
 148         char *hostname = exp->m_export.e_hostname;
 149         char *path;
 150         char *ptr;
 151
 152         path = strdup(exp->m_export.e_path);
 153         if (!path) {
 154                 xlog(L_WARNING, "v4root_add_parents: Unable to create "
 155                                 "pseudo export for '%s'", exp->m_export.e_path);
 156                 return -ENOMEM;
 157         }
 158         for (ptr = path; ptr; ptr = strchr(ptr, '/')) {
 159                 int ret;
 160                 char saved;
 161
 162                 saved = *ptr;
 163                 *ptr = '\0';
 164                 ret = pseudofs_update(hostname, *path ? path : "/", exp);
 165                 if (ret)
 166                         return ret;
 167                 *ptr = saved;
 168                 ptr++;
 169         }
 170         free(path);
 171         return 0;
 172 }
 173
 174 /*
 175  * Create pseudo exports by running through the real export
 176  * looking at the components of the path that make up the export.
 177  * Those path components, if not exported, will become pseudo
 178  * exports allowing them to be found when the kernel does an upcall
 179  * looking for components of the v4 mount.
 180  */
 181 void
 182 v4root_set()
 183 {
 184         nfs_export      *exp;
 185         int     i;
 186
 187         if (!v4root_needed)
 188                 return;
 189         if (!v4root_support())
 190                 return;
 191
 192         for (i = 0; i < MCL_MAXTYPES; i++) {
 193                 for (exp = exportlist[i].p_head; exp; exp = exp->m_next) {
 194                         if (exp->m_export.e_flags & NFSEXP_V4ROOT)
 195                                 /*
 196                                  * We just added this one, so its
 197                                  * parents are already dealt with!
 198                                  */
 199                                 continue;
 200
 201                         if (strcmp(exp->m_export.e_path, "/") == 0 &&
 202                             !(exp->m_export.e_flags & NFSEXP_FSID)) {
 203                                 /* Force '/' to be exported as fsid == 0*/
 204                                 exp->m_export.e_flags |= NFSEXP_FSID;
 205                                 exp->m_export.e_fsid = 0;
 206                         }
 207
 208                         v4root_add_parents(exp);
 209                         /* XXX: error handling! */
 210                 }
 211         }
 212 }