source3/smbd/oplock_linux.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    kernel oplock processing for Linux
   4    Copyright (C) Andrew Tridgell 2000
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #define DBGC_CLASS DBGC_LOCKING
  21 #include "includes.h"
  22 #include "system/filesys.h"
  23 #include "smbd/smbd.h"
  24 #include "smbd/globals.h"
  25
  26 #if HAVE_KERNEL_OPLOCKS_LINUX
  27
  28 #ifndef F_SETLEASE
  29 #define F_SETLEASE      1024
  30 #endif
  31
  32 #ifndef F_GETLEASE
  33 #define F_GETLEASE      1025
  34 #endif
  35
  36 #ifndef CAP_LEASE
  37 #define CAP_LEASE 28
  38 #endif
  39
  40 #ifndef RT_SIGNAL_LEASE
  41 #define RT_SIGNAL_LEASE (SIGRTMIN+1)
  42 #endif
  43
  44 #ifndef F_SETSIG
  45 #define F_SETSIG 10
  46 #endif
  47
  48 /*
  49  * public function to get linux lease capability. Needed by some VFS modules (eg. gpfs.c)
  50  */
  51 void linux_set_lease_capability(void)
  52 {
  53         set_effective_capability(LEASE_CAPABILITY);
  54 }
  55
  56 /*
  57  * Call to set the kernel lease signal handler
  58  */
  59 int linux_set_lease_sighandler(int fd)
  60 {
  61         if (fcntl(fd, F_SETSIG, RT_SIGNAL_LEASE) == -1) {
  62                 DEBUG(3,("Failed to set signal handler for kernel lease\n"));
  63                 return -1;
  64         }
  65
  66         return 0;
  67 }
  68
  69 /****************************************************************************
  70  Call SETLEASE. If we get EACCES then we try setting up the right capability and
  71  try again.
  72  Use the SMB_VFS_LINUX_SETLEASE instead of this call directly.
  73 ****************************************************************************/
  74
  75 int linux_setlease(int fd, int leasetype)
  76 {
  77         int ret;
  78         int saved_errno;
  79
  80         /*
  81          * Ensure the lease owner is root to allow
  82          * correct delivery of lease-break signals.
  83          */
  84
  85         become_root();
  86
  87         /* First set the signal handler. */
  88         if (linux_set_lease_sighandler(fd) == -1) {
  89                 saved_errno = errno;
  90                 ret = -1;
  91                 goto out;
  92         }
  93         ret = fcntl(fd, F_SETLEASE, leasetype);
  94         if (ret == -1) {
  95                 saved_errno = errno;
  96         }
  97
  98   out:
  99
 100         unbecome_root();
 101
 102         if (ret == -1) {
 103                 errno = saved_errno;
 104         }
 105         return ret;
 106 }
 107
 108 /****************************************************************************
 109  * Deal with the Linux kernel <--> smbd
 110  * oplock break protocol.
 111 ****************************************************************************/
 112
 113 static void linux_oplock_signal_handler(struct tevent_context *ev_ctx,
 114                                         struct tevent_signal *se,
 115                                         int signum, int count,
 116                                         void *_info, void *private_data)
 117 {
 118         struct kernel_oplocks *ctx =
 119                 talloc_get_type_abort(private_data,
 120                 struct kernel_oplocks);
 121         struct smbd_server_connection *sconn =
 122                 talloc_get_type_abort(ctx->private_data,
 123                 struct smbd_server_connection);
 124         siginfo_t *info = (siginfo_t *)_info;
 125         int fd = info->si_fd;
 126         files_struct *fsp;
 127
 128         /*
 129          * This function doesn't expect any specific impersonation, as it only
 130          * sends messages to other smbd processes. And messaging_send_iov_from()
 131          * already handles EACCES.
 132          */
 133
 134         fsp = file_find_fd(sconn, fd);
 135         if (fsp == NULL) {
 136                 DEBUG(0,("linux_oplock_signal_handler: failed to find fsp for file fd=%d (file was closed ?)\n", fd ));
 137                 return;
 138         }
 139         break_kernel_oplock(sconn->msg_ctx, fsp);
 140 }
 141
 142 /****************************************************************************
 143  Attempt to set an kernel oplock on a file.
 144 ****************************************************************************/
 145
 146 static bool linux_set_kernel_oplock(struct kernel_oplocks *ctx,
 147                                     files_struct *fsp, int oplock_type)
 148 {
 149         if ( SMB_VFS_LINUX_SETLEASE(fsp, F_WRLCK) == -1) {
 150                 DEBUG(3,("linux_set_kernel_oplock: Refused oplock on file %s, "
 151                          "fd = %d, file_id = %s. (%s)\n",
 152                          fsp_str_dbg(fsp), fsp->fh->fd,
 153                          file_id_string_tos(&fsp->file_id),
 154                          strerror(errno)));
 155                 return False;
 156         }
 157
 158         DEBUG(3,("linux_set_kernel_oplock: got kernel oplock on file %s, "
 159                  "file_id = %s gen_id = %lu\n",
 160                  fsp_str_dbg(fsp), file_id_string_tos(&fsp->file_id),
 161                  fsp->fh->gen_id));
 162
 163         return True;
 164 }
 165
 166 /****************************************************************************
 167  Release a kernel oplock on a file.
 168 ****************************************************************************/
 169
 170 static void linux_release_kernel_oplock(struct kernel_oplocks *ctx,
 171                                         files_struct *fsp, int oplock_type)
 172 {
 173         if (DEBUGLVL(10)) {
 174                 /*
 175                  * Check and print out the current kernel
 176                  * oplock state of this file.
 177                  */
 178                 int state = fcntl(fsp->fh->fd, F_GETLEASE, 0);
 179                 dbgtext("linux_release_kernel_oplock: file %s, file_id = %s "
 180                         "gen_id = %lu has kernel oplock state "
 181                         "of %x.\n", fsp_str_dbg(fsp),
 182                         file_id_string_tos(&fsp->file_id),
 183                         fsp->fh->gen_id, state );
 184         }
 185
 186         /*
 187          * Remove the kernel oplock on this file.
 188          */
 189         if ( SMB_VFS_LINUX_SETLEASE(fsp, F_UNLCK) == -1) {
 190                 if (DEBUGLVL(0)) {
 191                         dbgtext("linux_release_kernel_oplock: Error when "
 192                                 "removing kernel oplock on file " );
 193                         dbgtext("%s, file_id = %s, gen_id = %lu. "
 194                                 "Error was %s\n", fsp_str_dbg(fsp),
 195                                 file_id_string_tos(&fsp->file_id),
 196                                 fsp->fh->gen_id, strerror(errno) );
 197                 }
 198         }
 199 }
 200
 201 /****************************************************************************
 202  See if the kernel supports oplocks.
 203 ****************************************************************************/
 204
 205 static bool linux_oplocks_available(void)
 206 {
 207         int fd, ret;
 208         fd = open("/dev/null", O_RDONLY);
 209         if (fd == -1)
 210                 return False; /* uggh! */
 211         ret = fcntl(fd, F_GETLEASE, 0);
 212         close(fd);
 213         return ret == F_UNLCK;
 214 }
 215
 216 /****************************************************************************
 217  Setup kernel oplocks.
 218 ****************************************************************************/
 219
 220 static const struct kernel_oplocks_ops linux_koplocks = {
 221         .set_oplock                     = linux_set_kernel_oplock,
 222         .release_oplock                 = linux_release_kernel_oplock,
 223         .contend_level2_oplocks_begin   = NULL,
 224         .contend_level2_oplocks_end     = NULL,
 225 };
 226
 227 struct kernel_oplocks *linux_init_kernel_oplocks(struct smbd_server_connection *sconn)
 228 {
 229         struct kernel_oplocks *ctx;
 230         struct tevent_signal *se;
 231
 232         if (!linux_oplocks_available()) {
 233                 DEBUG(3,("Linux kernel oplocks not available\n"));
 234                 return NULL;
 235         }
 236
 237         ctx = talloc_zero(sconn, struct kernel_oplocks);
 238         if (!ctx) {
 239                 DEBUG(0,("Linux Kernel oplocks talloc_Zero failed\n"));
 240                 return NULL;
 241         }
 242
 243         ctx->ops = &linux_koplocks;
 244         ctx->private_data = sconn;
 245
 246         /*
 247          * linux_oplock_signal_handler() only
 248          * sends messages to other smbd processes
 249          * and doesn't require any impersonation.
 250          * So we can just use the raw tevent_context.
 251          */
 252         se = tevent_add_signal(sconn->raw_ev_ctx,
 253                                ctx,
 254                                RT_SIGNAL_LEASE, SA_SIGINFO,
 255                                linux_oplock_signal_handler,
 256                                ctx);
 257         if (!se) {
 258                 DEBUG(0,("Failed to setup RT_SIGNAL_LEASE handler"));
 259                 TALLOC_FREE(ctx);
 260                 return NULL;
 261         }
 262
 263         DEBUG(3,("Linux kernel oplocks enabled\n"));
 264
 265         return ctx;
 266 }
 267 #else
 268  void oplock_linux_dummy(void);
 269
 270  void oplock_linux_dummy(void) {}
 271 #endif /* HAVE_KERNEL_OPLOCKS_LINUX */