source/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 2 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, write to the Free Software
  18    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19 */
  20
  21 #include "includes.h"
  22
  23 #if HAVE_KERNEL_OPLOCKS_LINUX
  24
  25 static SIG_ATOMIC_T signals_received;
  26 #define FD_PENDING_SIZE 100
  27 static SIG_ATOMIC_T fd_pending_array[FD_PENDING_SIZE];
  28
  29 #ifndef F_SETLEASE
  30 #define F_SETLEASE      1024
  31 #endif
  32
  33 #ifndef F_GETLEASE
  34 #define F_GETLEASE      1025
  35 #endif
  36
  37 #ifndef CAP_LEASE
  38 #define CAP_LEASE 28
  39 #endif
  40
  41 #ifndef RT_SIGNAL_LEASE
  42 #define RT_SIGNAL_LEASE (SIGRTMIN+1)
  43 #endif
  44
  45 #ifndef F_SETSIG
  46 #define F_SETSIG 10
  47 #endif
  48
  49 /****************************************************************************
  50  Handle a LEASE signal, incrementing the signals_received and blocking the signal.
  51 ****************************************************************************/
  52
  53 static void signal_handler(int sig, siginfo_t *info, void *unused)
  54 {
  55         if (signals_received < FD_PENDING_SIZE - 1) {
  56                 fd_pending_array[signals_received] = (SIG_ATOMIC_T)info->si_fd;
  57                 signals_received++;
  58         } /* Else signal is lost. */
  59         sys_select_signal();
  60 }
  61
  62 /****************************************************************************
  63  Try to gain a linux capability.
  64 ****************************************************************************/
  65
  66 static void set_capability(unsigned capability)
  67 {
  68 #ifndef _LINUX_CAPABILITY_VERSION
  69 #define _LINUX_CAPABILITY_VERSION 0x19980330
  70 #endif
  71         /* these can be removed when they are in glibc headers */
  72         struct  {
  73                 uint32 version;
  74                 int pid;
  75         } header;
  76         struct {
  77                 uint32 effective;
  78                 uint32 permitted;
  79                 uint32 inheritable;
  80         } data;
  81
  82         header.version = _LINUX_CAPABILITY_VERSION;
  83         header.pid = 0;
  84
  85         if (capget(&header, &data) == -1) {
  86                 DEBUG(3,("Unable to get kernel capabilities (%s)\n", strerror(errno)));
  87                 return;
  88         }
  89
  90         data.effective |= (1<<capability);
  91
  92         if (capset(&header, &data) == -1) {
  93                 DEBUG(3,("Unable to set %d capability (%s)\n",
  94                          capability, strerror(errno)));
  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
 103 static int linux_setlease(int fd, int leasetype)
 104 {
 105         int ret;
 106
 107         if (fcntl(fd, F_SETSIG, RT_SIGNAL_LEASE) == -1) {
 108                 DEBUG(3,("Failed to set signal handler for kernel lease\n"));
 109                 return -1;
 110         }
 111
 112         ret = fcntl(fd, F_SETLEASE, leasetype);
 113         if (ret == -1 && errno == EACCES) {
 114                 set_capability(CAP_LEASE);
 115                 ret = fcntl(fd, F_SETLEASE, leasetype);
 116         }
 117
 118         return ret;
 119 }
 120
 121 /****************************************************************************
 122  * Deal with the Linux kernel <--> smbd
 123  * oplock break protocol.
 124 ****************************************************************************/
 125
 126 static BOOL linux_oplock_receive_message(fd_set *fds, char *buffer, int buffer_len)
 127 {
 128         int fd;
 129         struct files_struct *fsp;
 130
 131         BlockSignals(True, RT_SIGNAL_LEASE);
 132         fd = fd_pending_array[0];
 133         fsp = file_find_fd(fd);
 134         fd_pending_array[0] = (SIG_ATOMIC_T)-1;
 135         if (signals_received > 1)
 136                 memmove((void *)&fd_pending_array[0], (void *)&fd_pending_array[1],
 137                         sizeof(SIG_ATOMIC_T)*(signals_received-1));
 138         signals_received--;
 139         /* now we can receive more signals */
 140         BlockSignals(False, RT_SIGNAL_LEASE);
 141
 142         if (fsp == NULL) {
 143                 DEBUG(0,("Invalid file descriptor %d in kernel oplock break!\n", (int)fd));
 144                 return False;
 145         }
 146
 147         DEBUG(3,("linux_oplock_receive_message: kernel oplock break request received for \
 148 dev = %x, inode = %.0f fd = %d, fileid = %lu \n", (unsigned int)fsp->dev, (double)fsp->inode,
 149                         fd, fsp->file_id));
 150
 151         /*
 152          * Create a kernel oplock break message.
 153          */
 154
 155         /* Setup the message header */
 156         SIVAL(buffer,OPBRK_CMD_LEN_OFFSET,KERNEL_OPLOCK_BREAK_MSG_LEN);
 157         SSVAL(buffer,OPBRK_CMD_PORT_OFFSET,0);
 158
 159         buffer += OPBRK_CMD_HEADER_LEN;
 160
 161         SSVAL(buffer,OPBRK_MESSAGE_CMD_OFFSET,KERNEL_OPLOCK_BREAK_CMD);
 162
 163         memcpy(buffer + KERNEL_OPLOCK_BREAK_DEV_OFFSET, (char *)&fsp->dev, sizeof(fsp->dev));
 164         memcpy(buffer + KERNEL_OPLOCK_BREAK_INODE_OFFSET, (char *)&fsp->inode, sizeof(fsp->inode));
 165         memcpy(buffer + KERNEL_OPLOCK_BREAK_FILEID_OFFSET, (char *)&fsp->file_id, sizeof(fsp->file_id));
 166
 167         return True;
 168 }
 169
 170 /****************************************************************************
 171  Attempt to set an kernel oplock on a file.
 172 ****************************************************************************/
 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,("linux_set_kernel_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,("linux_set_kernel_oplock: got kernel oplock on file %s, dev = %x, inode = %.0f, file_id = %lu\n",
 185                   fsp->fsp_name, (unsigned int)fsp->dev, (double)fsp->inode, fsp->file_id));
 186
 187         return True;
 188 }
 189
 190 /****************************************************************************
 191  Release a kernel oplock on a file.
 192 ****************************************************************************/
 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("linux_release_kernel_oplock: file %s, dev = %x, inode = %.0f file_id = %lu has kernel \
 203 oplock state of %x.\n", fsp->fsp_name, (unsigned int)fsp->dev,
 204                         (double)fsp->inode, fsp->file_id, 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("linux_release_kernel_oplock: Error when removing kernel oplock on file " );
 213                         dbgtext("%s, dev = %x, inode = %.0f, file_id = %lu. Error was %s\n",
 214                                 fsp->fsp_name, (unsigned int)fsp->dev,
 215                                 (double)fsp->inode, fsp->file_id, strerror(errno) );
 216                 }
 217         }
 218 }
 219
 220 /****************************************************************************
 221  Parse a kernel oplock message.
 222 ****************************************************************************/
 223
 224 static BOOL linux_kernel_oplock_parse(char *msg_start, int msg_len, SMB_INO_T *inode,
 225                 SMB_DEV_T *dev, unsigned long *file_id)
 226 {
 227         /* Ensure that the msg length is correct. */
 228         if (msg_len != KERNEL_OPLOCK_BREAK_MSG_LEN) {
 229                 DEBUG(0,("incorrect length for KERNEL_OPLOCK_BREAK_CMD (was %d, should be %lu).\n",
 230                          msg_len, (unsigned long)KERNEL_OPLOCK_BREAK_MSG_LEN));
 231                 return False;
 232         }
 233
 234         memcpy((char *)inode, msg_start+KERNEL_OPLOCK_BREAK_INODE_OFFSET, sizeof(*inode));
 235         memcpy((char *)dev, msg_start+KERNEL_OPLOCK_BREAK_DEV_OFFSET, sizeof(*dev));
 236         memcpy((char *)file_id, msg_start+KERNEL_OPLOCK_BREAK_FILEID_OFFSET, sizeof(*file_id));
 237
 238         DEBUG(3,("kernel oplock break request for file dev = %x, inode = %.0f, file_id = %lu\n",
 239                 (unsigned int)*dev, (double)*inode, *file_id));
 240
 241         return True;
 242 }
 243
 244 /****************************************************************************
 245  See if a oplock message is waiting.
 246 ****************************************************************************/
 247
 248 static BOOL linux_oplock_msg_waiting(fd_set *fds)
 249 {
 250         return signals_received != 0;
 251 }
 252
 253 /****************************************************************************
 254  See if the kernel supports oplocks.
 255 ****************************************************************************/
 256
 257 static BOOL linux_oplocks_available(void)
 258 {
 259         int fd, ret;
 260         fd = open("/dev/null", O_RDONLY);
 261         if (fd == -1)
 262                 return False; /* uggh! */
 263         ret = fcntl(fd, F_GETLEASE, 0);
 264         close(fd);
 265         return ret == F_UNLCK;
 266 }
 267
 268 /****************************************************************************
 269  Setup kernel oplocks.
 270 ****************************************************************************/
 271
 272 struct kernel_oplocks *linux_init_kernel_oplocks(void)
 273 {
 274         static struct kernel_oplocks koplocks;
 275         struct sigaction act;
 276
 277         if (!linux_oplocks_available()) {
 278                 DEBUG(3,("Linux kernel oplocks not available\n"));
 279                 return NULL;
 280         }
 281
 282         ZERO_STRUCT(act);
 283
 284         act.sa_handler = NULL;
 285         act.sa_sigaction = signal_handler;
 286         act.sa_flags = SA_SIGINFO;
 287         sigemptyset( &act.sa_mask );
 288         if (sigaction(RT_SIGNAL_LEASE, &act, NULL) != 0) {
 289                 DEBUG(0,("Failed to setup RT_SIGNAL_LEASE handler\n"));
 290                 return NULL;
 291         }
 292
 293         koplocks.receive_message = linux_oplock_receive_message;
 294         koplocks.set_oplock = linux_set_kernel_oplock;
 295         koplocks.release_oplock = linux_release_kernel_oplock;
 296         koplocks.parse_message = linux_kernel_oplock_parse;
 297         koplocks.msg_waiting = linux_oplock_msg_waiting;
 298         koplocks.notification_fd = -1;
 299
 300         /* the signal can start off blocked due to a bug in bash */
 301         BlockSignals(False, RT_SIGNAL_LEASE);
 302
 303         DEBUG(3,("Linux kernel oplocks enabled\n"));
 304
 305         return &koplocks;
 306 }
 307 #else
 308  void oplock_linux_dummy(void) {}
 309 #endif /* HAVE_KERNEL_OPLOCKS_LINUX */