source/smbd/oplock_linux.c

   1 /*
   2    Unix SMB/Netbios implementation.
   3    Version 3.0
   4    kernel oplock processing for Linux
   5    Copyright (C) Andrew Tridgell 2000
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20 */
  21
  22 #include "includes.h"
  23
  24 #if HAVE_KERNEL_OPLOCKS_LINUX
  25
  26 extern int DEBUGLEVEL;
  27
  28 static VOLATILE SIG_ATOMIC_T signals_received;
  29 static VOLATILE SIG_ATOMIC_T signals_processed;
  30 static VOLATILE SIG_ATOMIC_T fd_pending; /* the fd of the current pending signal */
  31
  32 #ifndef F_SETLEASE
  33 #define F_SETLEASE      1024
  34 #endif
  35
  36 #ifndef F_GETLEASE
  37 #define F_GETLEASE      1025
  38 #endif
  39
  40 #ifndef CAP_LEASE
  41 #define CAP_LEASE 28
  42 #endif
  43
  44 #ifndef RT_SIGNAL_LEASE
  45 #define RT_SIGNAL_LEASE 33
  46 #endif
  47
  48 #ifndef F_SETSIG
  49 #define F_SETSIG 10
  50 #endif
  51
  52 /****************************************************************************
  53 handle a LEASE signal, incrementing the signals_received and blocking the signal
  54 ****************************************************************************/
  55 static void signal_handler(int signal, siginfo_t *info, void *unused)
  56 {
  57         BlockSignals(True, signal);
  58         fd_pending = (SIG_ATOMIC_T)info->si_fd;
  59         signals_received++;
  60         sys_select_signal();
  61 }
  62
  63 /****************************************************************************
  64 try to gain a linux capability
  65 ****************************************************************************/static void set_capability(unsigned capability)
  66 {
  67 #ifndef _LINUX_CAPABILITY_VERSION
  68 #define _LINUX_CAPABILITY_VERSION 0x19980330
  69 #endif
  70         /* these can be removed when they are in glibc headers */
  71         struct  {
  72                 uint32 version;
  73                 int pid;
  74         } header;
  75         struct {
  76                 uint32 effective;
  77                 uint32 permitted;
  78                 uint32 inheritable;
  79         } data;
  80
  81         header.version = _LINUX_CAPABILITY_VERSION;
  82         header.pid = 0;
  83
  84         if (capget(&header, &data) == -1) {
  85                 DEBUG(3,("Unable to get kernel capabilities (%s)\n", strerror(errno)));
  86                 return;
  87         }
  88
  89         data.effective |= (1<<capability);
  90
  91         if (capset(&header, &data) == -1) {
  92                 DEBUG(3,("Unable to set %d capability (%s)\n",
  93                          capability, strerror(errno)));
  94         }
  95 }
  96
  97
  98 /****************************************************************************
  99 call SETLEASE. If we get EACCES then we try setting up the right capability and
 100 try again
 101 ****************************************************************************/
 102 static int linux_setlease(int fd, int leasetype)
 103 {
 104         int ret;
 105
 106         if (fcntl(fd, F_SETSIG, RT_SIGNAL_LEASE) == -1) {
 107                 DEBUG(3,("Failed to set signal handler for kernel lease\n"));
 108                 return -1;
 109         }
 110
 111         ret = fcntl(fd, F_SETLEASE, leasetype);
 112         if (ret == -1 && errno == EACCES) {
 113                 set_capability(CAP_LEASE);
 114                 ret = fcntl(fd, F_SETLEASE, leasetype);
 115         }
 116
 117         return ret;
 118 }
 119
 120
 121 /****************************************************************************
 122  * Deal with the Linux kernel <--> smbd
 123  * oplock break protocol.
 124 ****************************************************************************/
 125 static BOOL linux_oplock_receive_message(fd_set *fds, char *buffer, int buffer_len)
 126 {
 127         SMB_DEV_T dev;
 128         SMB_INO_T inode;
 129         SMB_STRUCT_STAT sbuf;
 130         BOOL ret;
 131
 132         if (signals_received == signals_processed) return False;
 133
 134         if (sys_fstat((int)fd_pending,&sbuf) == -1) {
 135                 DEBUG(0,("Invalid file descriptor %d in kernel oplock break!\n", (int)fd_pending));
 136                 ret = False;
 137                 goto out;
 138         }
 139
 140         dev = sbuf.st_dev;
 141         inode = sbuf.st_ino;
 142
 143         DEBUG(3,("receive_local_message: kernel oplock break request received for \
 144 dev = %x, inode = %.0f\n", (unsigned int)dev, (double)inode ));
 145
 146         /*
 147          * Create a kernel oplock break message.
 148          */
 149
 150         /* Setup the message header */
 151         SIVAL(buffer,OPBRK_CMD_LEN_OFFSET,KERNEL_OPLOCK_BREAK_MSG_LEN);
 152         SSVAL(buffer,OPBRK_CMD_PORT_OFFSET,0);
 153
 154         buffer += OPBRK_CMD_HEADER_LEN;
 155
 156         SSVAL(buffer,OPBRK_MESSAGE_CMD_OFFSET,KERNEL_OPLOCK_BREAK_CMD);
 157
 158         memcpy(buffer + KERNEL_OPLOCK_BREAK_DEV_OFFSET, (char *)&dev, sizeof(dev));
 159         memcpy(buffer + KERNEL_OPLOCK_BREAK_INODE_OFFSET, (char *)&inode, sizeof(inode));
 160
 161  out:
 162         /* now we can receive more signals */
 163         fd_pending = (SIG_ATOMIC_T)-1;
 164         signals_processed++;
 165         BlockSignals(False, RT_SIGNAL_LEASE);
 166
 167         return True;
 168 }
 169
 170
 171 /****************************************************************************
 172  Attempt to set an kernel oplock on a file.
 173 ****************************************************************************/
 174 static BOOL linux_set_kernel_oplock(files_struct *fsp, int oplock_type)
 175 {
 176         if (linux_setlease(fsp->fd, F_WRLCK) == -1) {
 177                 DEBUG(3,("set_file_oplock: Refused oplock on file %s, fd = %d, dev = %x, \
 178 inode = %.0f. (%s)\n",
 179                          fsp->fsp_name, fsp->fd,
 180                          (unsigned int)fsp->dev, (double)fsp->inode, strerror(errno)));
 181                 return False;
 182         }
 183
 184         DEBUG(3,("set_file_oplock: got kernel oplock on file %s, dev = %x, inode = %.0f\n",
 185                   fsp->fsp_name, (unsigned int)fsp->dev, (double)fsp->inode));
 186
 187         return True;
 188 }
 189
 190
 191 /****************************************************************************
 192  Release a kernel oplock on a file.
 193 ****************************************************************************/
 194 static void linux_release_kernel_oplock(files_struct *fsp)
 195 {
 196         if (DEBUGLVL(10)) {
 197                 /*
 198                  * Check and print out the current kernel
 199                  * oplock state of this file.
 200                  */
 201                 int state = fcntl(fsp->fd, F_GETLEASE, 0);
 202                 dbgtext("release_kernel_oplock: file %s, dev = %x, inode = %.0f has kernel \
 203 oplock state of %x.\n", fsp->fsp_name, (unsigned int)fsp->dev,
 204                         (double)fsp->inode, state );
 205         }
 206
 207         /*
 208          * Remove the kernel oplock on this file.
 209          */
 210         if (linux_setlease(fsp->fd, F_UNLCK) == -1) {
 211                 if (DEBUGLVL(0)) {
 212                         dbgtext("release_kernel_oplock: Error when removing kernel oplock on file " );
 213                         dbgtext("%s, dev = %x, inode = %.0f. Error was %s\n",
 214                                 fsp->fsp_name, (unsigned int)fsp->dev,
 215                                 (double)fsp->inode, strerror(errno) );
 216                 }
 217         }
 218 }
 219
 220
 221 /****************************************************************************
 222 parse a kernel oplock message
 223 ****************************************************************************/
 224 static BOOL linux_kernel_oplock_parse(char *msg_start, int msg_len, SMB_INO_T *inode, SMB_DEV_T *dev)
 225 {
 226         /* Ensure that the msg length is correct. */
 227         if (msg_len != KERNEL_OPLOCK_BREAK_MSG_LEN) {
 228                 DEBUG(0,("incorrect length for KERNEL_OPLOCK_BREAK_CMD (was %d, should be %d).\n",
 229                          msg_len, KERNEL_OPLOCK_BREAK_MSG_LEN));
 230                 return False;
 231         }
 232
 233         memcpy((char *)inode, msg_start+KERNEL_OPLOCK_BREAK_INODE_OFFSET, sizeof(*inode));
 234         memcpy((char *)dev, msg_start+KERNEL_OPLOCK_BREAK_DEV_OFFSET, sizeof(*dev));
 235
 236         DEBUG(3,("kernel oplock break request for file dev = %x, inode = %.0f\n",
 237                  (unsigned int)*dev, (double)*inode));
 238
 239         return True;
 240 }
 241
 242
 243 /****************************************************************************
 244 see if a oplock message is waiting
 245 ****************************************************************************/
 246 static BOOL linux_oplock_msg_waiting(fd_set *fds)
 247 {
 248         return signals_processed != signals_received;
 249 }
 250
 251 /****************************************************************************
 252 see if the kernel supports oplocks
 253 ****************************************************************************/
 254 static BOOL linux_oplocks_available(void)
 255 {
 256         int fd, ret;
 257         fd = open("/dev/null", O_RDONLY);
 258         if (fd == -1) return False; /* uggh! */
 259         ret = fcntl(fd, F_GETLEASE, 0);
 260         close(fd);
 261         return ret == F_UNLCK;
 262 }
 263
 264
 265 /****************************************************************************
 266 setup kernel oplocks
 267 ****************************************************************************/
 268 struct kernel_oplocks *linux_init_kernel_oplocks(void)
 269 {
 270         static struct kernel_oplocks koplocks;
 271         struct sigaction act;
 272
 273         if (!linux_oplocks_available()) {
 274                 DEBUG(3,("Linux kernel oplocks not available\n"));
 275                 return NULL;
 276         }
 277
 278         act.sa_handler = NULL;
 279         act.sa_sigaction = signal_handler;
 280         act.sa_flags = SA_SIGINFO;
 281         if (sigaction(RT_SIGNAL_LEASE, &act, NULL) != 0) {
 282                 DEBUG(0,("Failed to setup RT_SIGNAL_LEASE handler\n"));
 283                 return NULL;
 284         }
 285
 286         koplocks.receive_message = linux_oplock_receive_message;
 287         koplocks.set_oplock = linux_set_kernel_oplock;
 288         koplocks.release_oplock = linux_release_kernel_oplock;
 289         koplocks.parse_message = linux_kernel_oplock_parse;
 290         koplocks.msg_waiting = linux_oplock_msg_waiting;
 291         koplocks.notification_fd = -1;
 292
 293         DEBUG(3,("Linux kernel oplocks enabled\n"));
 294
 295         return &koplocks;
 296 }
 297
 298
 299
 300 #else
 301  void oplock_linux_dummy(void) {}
 302 #endif /* HAVE_KERNEL_OPLOCKS_LINUX */