devfsd.c

devfsd 驱动对linux的补丁支持

/*  devfsd.c

    Main file for  devfsd  (devfs daemon for Linux).

    Copyright (C) 1998-2002  Richard Gooch

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

    Richard Gooch may be reached by email at  [e-mail]
    The postal address is:
      Richard Gooch, c/o ATNF, P. O. Box 76, Epping, N.S.W., 2121, Australia.
*/

/*
    This programme will manage the devfs filesystem.


    Written by      Richard Gooch   9-AUG-1998

    Updated by      Richard Gooch   11-AUG-1998

    Updated by      Richard Gooch   10-SEP-1998: Added support for asynchronous
  open and close events.

    Updated by      Richard Gooch   11-SEP-1998: Fixed bug in <read_config>
  where <<line>> pointer was dereferenced before being initialised.

    Updated by      Richard Gooch   9-JUN-1999: Added variable expansion
  support.

    Updated by      Richard Gooch   10-JUN-1999: Added "devname" variable and
  renamed "device" variable name to "devpath". Fixed bug in argument handling.
  Added "-d" switch.

    Updated by      Richard Gooch   13-JUN-1999: Added compile-time check of
  protocol revision.

    Updated by      Richard Gooch   14-JUN-1999: Stat inode instead of using
  device entry information (which may be out of date).

    Updated by      Richard Gooch   15-JUN-1999: Added tracing output. Thanks
  to Piete Brooks <[e-mail]>.

    Updated by      Richard Gooch   16-JUN-1999: Added action structure.

    Updated by      Richard Gooch   17-JUN-1999: Added "hostname" and "mntpnt"
  variables. Added nesting of include files. Added "CLEAR_CONFIG" key.

    Updated by      Richard Gooch   18-JUN-1999: Added "OPTIONAL_INCLUDE" key.
  Added ignore actions. Added event mask.

    Updated by      Richard Gooch   24-JUN-1999: Switched to separated event
  and action config file specifiers.

    Updated by      Richard Gooch   20-OCT-1999: Fixed typo in debugging output

    Updated by      Richard Gooch   24-OCT-1999: Added "-fg" switch and
  redefined tracing levels. Delay opening syslog until /dev/log appears. Scan
  mounted FS and generate synthetic REGISTER events.

    Updated by      Richard Gooch   25-OCT-1999: Added compatibility actions.
  Added compatibility entries for sound, printer, video4linux, parallel port
  and frame buffer drivers.

    Updated by      Richard Gooch   26-OCT-1999: Incremented protocol revision
  to 5. Extract major and minor number in <do_scan_and_service>. Added
  compatibility entries for SoundBlaster CD-ROM, netlink, SCSI generic and
  SCSI tape drivers.

    Updated by      Richard Gooch   30-OCT-1999: Added entries for /dev/st,
  /dev/sg and /dev/sr hierarchies. Added compatibility entries for loop, IDE
  tape and SCSI CD-ROM drivers.

    Updated by      Richard Gooch   31-OCT-1999: Added compatibility entries
  for floppy, RAMDISC, meta-device, SCSI disc, IDE disc and IDE CD-ROM drivers.
  Added entries for /dev/sd, /dev/ide/hd and /dev/ide/cd hierarchies.

    Updated by      Richard Gooch   3-NOV-1999: Created <make_symlink> which
  will create intermediate directories as required. Updated compatibility code
  for IDE tapes. Added entries for /dev/ide/mt hierarchy.

    Updated by      Richard Gooch   4-NOV-1999: Added compatibility entries for
  virtual console capture, serial and console devices.

    Updated by      Richard Gooch   5-NOV-1999: Added compatibility entries for
  BSD pty devices.

    Updated by      Richard Gooch   11-NOV-1999: Only show messages about
  compatibility entries being created or destroyed when in trace mode.

    Updated by      Richard Gooch   21-NOV-1999: Added compatibility entries
  for joystick devices.

    Updated by      Richard Gooch   6-DEC-1999: Change directory to devfs FS.

    Updated by      Richard Gooch   9-DEC-1999: Support compiling with 2.2.x
  kernels.

    Updated by      Richard Gooch   15-DEC-1999: Added compatibility entries
  for miscellaneous character devices.

    Updated by      Richard Gooch   17-DEC-1999: Do not grab event queue when
  just setting devfs debug mask.

    Updated by      Richard Gooch   20-DEC-1999: Swap pathname and action
  fields in config file.

    Updated by      Richard Gooch   25-DEC-1999: Discard lookups on "/dev/log"
  and "/dev/initctl". Added "MODLOAD" action.

    Updated by      Richard Gooch   3-FEB-2000: Bitch and moan if modprobe(8)
  is used with "EXECUTE" action.

    Updated by      Richard Gooch   3-MAR-2000: Bug fix with inclusion
  directives.

    Updated by      Richard Gooch   6-MAR-2000: Support negative UID and GID in
  config file. Thanks to Chris Richards <[e-mail]>.

    Updated by      Richard Gooch   12-APR-2000: More efficient discarding of
  lookups on "/dev/log" and "/dev/initctl".

    Updated by      Richard Gooch   16-APR-2000: Added "MFUNCTION" and
  "CFUNCTION" actions. Added compatibility entries for Computone Multiport
  serial devices.

    Updated by      Richard Gooch   17-APR-2000: Added "COPY" action.

    Updated by      Richard Gooch   18-APR-2000: Moved some things to header
  "devfsd.h". Removed special argument "ENTRY" and renamed "INFO" to "EVENT"
  for "CFUNCTION" action. Bug fix in debug mode with shared objects.

    Updated by      Richard Gooch   20-APR-2000: Changed version macro.

    Updated by      Richard Gooch   24-APR-2000: Created a table of rules for
  simple compatibility translations. Split part of <read_config> into
  <process_config_line>, in preparation for NIS support.

    Updated by      Richard Gooch   26-APR-2000: Added NIS configuration
  support.

    Updated by      Richard Gooch   27-APR-2000: Fixed DIR leak. Generate
  synthetic REGISTER events on SIGHUP. Silently ignore NIS attempts when no
  NIS domain set.

    Updated by      Richard Gooch   30-APR-2000: Moved parts of <action_compat>
  to <get_old_name> in compat_name.c. Simplified <action_compat> for SCSI and
  IDE new compatibilty entries.

    Updated by      Richard Gooch   10-JUN-2000: Moved version string to
  version.h

    Updated by      Richard Gooch   3-JUL-2000: Added "-C /etc/modules.devfs"
  when calling modprobe(8). Fail if a configuration line has EXECUTE modprobe.

    Updated by      Richard Gooch   4-JUL-2000: Added #define __USE_GNU. Thanks
  to Adam J. Richter <[e-mail]>.

    Updated by      Chris Rankin    21-JAN-2001: Allow the daemon to substitute
  regular expressions, similarly to sed. E.g. the expression ^foo\([0-9]\)$ has
  a subexpression within the \(, \) markers. The string foo4 matches this
  expression: the tag \0 would be replaced by "foo4", its first subexpression
  \1 by "4", etc.

    Updated by      Richard Gooch   5-FEB-2001: Switched from __USE_GNU to
  _GNU_SOURCE, according to recommendation from Ulrich. Do dummy opens of
  /dev/null so that fds [0:2] are open (and thus may be safely closed later).

    Updated by      Richard Gooch   21-FEB-2001: Bug fix in function
  <action_call_function>: a failed MFUNCTION would result in a bogus CFUNCTION
  being called.

    Updated by      Richard Gooch   27-JUL-2001: Bug fixes when execvp(3) fails
  (child did not exit).

    Updated by      Richard Gooch   30-JUL-2001: Applied and cleaned up patch
  by Chris Rankin (regular subexpression support). Fixed potential buffer
  overrun problems by using <snprintf>. Thanks to Sebastian Krahmer
  <[e-mail]>. Added "-np" switch. Thanks to John Fremlin.

    Updated by      Richard Gooch   31-JUL-2001: Added support for DELETE
  event. Added debug trace to <action_modload>.

    Updated by      Richard Gooch   8-AUG-2001: Added support for recursively
  reading config directories.

    Updated by      Richard Gooch   10-AUG-2001: Fixed support for recursively
  reading config directories.

    Updated by      Richard Gooch   14-AUG-2001: Move opendir(3) call to
  <do_scan_and_service>. Be more tolerant of some system errors. Fixed file
  descriptor leak in <action_copy>.

    Updated by      Richard Gooch   18-AUG-2001: Dynamically load libnsl at
  run-time as needed, rather than linking. Based on patch from Adam J. Richter.

    Updated by      Richard Gooch   19-AUG-2001: Switched to stat(2) in
  <action_permissions> to avoid harmless false positives. Return 0 instead of
  exiting if passwd or group entry not found in database. Do not exit in
  <action_execute> if fork(2) fails.

    Updated by      Richard Gooch   16-SEP-2001: Set environment to "safe mode"
  when invoking modprobe. Generate error message if /lib/modutils.so doesn't
  contain "modprobe" symbol. Add debugging message if /lib/modutils.so missing.
  Based on patch from Russell Coker.

    Updated by      Richard Gooch   6-NOV-2001: Called setsid(2) when closing
  fds[0:2] so that hangups from the old controlling terminal are ignored.

    Updated by      Richard Gooch   22-NOV-2001: Moved call to setsid(2) to
  immediately after forking child/daemon. Added call to setpgid(2) if running
  in the foreground. These changes are in anticipation of a kernel switch from
  ancestor process checking to process group checking.

    Updated by      Richard Gooch   25-NOV-2001: Created <<event_types>> table.
  Generate synthetic REGISTER event for directories in <do_scan_and_service>.

    Updated by      Richard Gooch   28-NOV-2001: Renamed <make_symlink> to
  <mksymlink> and made it global. Changed to return 0 on "success".

    Updated by      Richard Gooch   29-NOV-2001: Changed <action_copy> to set
  sticky bit as required. Added "RESTORE" key.

    Updated by      Richard Gooch   1-JAN-2002: Changed to extended regular
  expressions.

    Updated by      Richard Gooch   14-JAN-2002: Fixed dummy opens of
  /dev/null so that fds [0:2] are open (was only doing fds [0:1]) and prevent
  infinite loop if /dev/null cannot be opened.

    Updated by      Richard Gooch   20-JAN-2002: Fixed <action_compat> to
  ignore new compatibility names for IDE devices.

    Updated by      Richard Gooch   14-FEB-2002: Do not re-read config file if
  signals other than SIGHUP are caught.

    Updated by      Richard Gooch   6-MAR-2002: Catch SIGUSR1.

    Updated by      Richard Gooch   8-MAR-2002: Make /lib/devfsd the default
  directory for shared objects.

    Updated by      Richard Gooch   14-MAR-2002: Set close-on-exec flag for
  .devfsd control file.

    Last updated by Richard Gooch   21-MAR-2002: Set umask so that mknod(2),
  open(2) and mkdir(2) have complete control over permissions.


*/
#define _GNU_SOURCE
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <pwd.h>
#include <grp.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <dirent.h>
#include <fcntl.h>
#include <linux/devfs_fs.h>
#include <linux/kdev_t.h>
#include <syslog.h>
#include <signal.h>
#include <regex.h>
#include <errno.h>
#include <dlfcn.h>
#include <rpcsvc/ypclnt.h>
#include <rpcsvc/yp_prot.h>
#include <karma.h>
#include "devfsd.h"
#include "version.h"

#ifndef RTLD_DEFAULT  /*  Libc 5 doesn't define it, but it works  */
#  define RTLD_DEFAULT NULL
#endif

#define CONFIG_FILE  "/etc/devfsd.conf"
#define MAX_ARGS     (6 + 1)
#define MAX_SUBEXPR  10

/*  Update only after changing code to reflect new protocol  */
#define DEVFSD_PROTOCOL_REVISION_DAEMON  5

/*  Compile-time check  */
#if DEVFSD_PROTOCOL_REVISION_KERNEL != DEVFSD_PROTOCOL_REVISION_DAEMON
#error protocol version mismatch. Update your kernel headers
#endif

#define MKACTION(what,when) (struct action_type) {what, when}

#define AC_PERMISSIONS              0
#define AC_MODLOAD                  1
#define AC_EXECUTE                  2
#define AC_MFUNCTION                3
#define AC_CFUNCTION                4
#define AC_COPY                     5
#define AC_IGNORE                   6
#define AC_MKOLDCOMPAT              7
#define AC_MKNEWCOMPAT              8
#define AC_RMOLDCOMPAT              9
#define AC_RMNEWCOMPAT             10
#define AC_RESTORE                 11


struct permissions_type
{
    mode_t mode;
    uid_t uid;
    gid_t gid;
};

struct execute_type
{
    char *argv[MAX_ARGS + 1];  /*  argv[0] must always be the programme  */
};

struct call_function_type
{
    struct shared_object *so;
    union
    {
	int (*m) (int argc, char **argv);
	int (*c) (void *arg1, void *arg2, void *arg3, void *arg4, void *arg5);
    }
    func;
    char *argv[MAX_ARGS + 1];  /*  argv[0] is the function name          */
};

struct copy_type
{
    const char *source;
    const char *destination;
};

struct action_type
{
    unsigned int what;
    unsigned int when;
};

struct config_entry_struct
{
    struct action_type action;
    regex_t preg;
    union
    {
	struct permissions_type permissions;
	struct execute_type execute;
	struct call_function_type function;
	struct copy_type copy;
    }
    u;
    struct config_entry_struct *next;
};

struct get_variable_info
{
    const struct devfsd_notify_struct *info;
    CONST char *devname;
    char devpath[STRING_LENGTH];
};

struct shared_object
{
    CONST char *name;
    void *handle;
    struct shared_object *next;
};


/*  External functions  */
EXTERN_FUNCTION (flag st_expr_expand,
		 (char *output, unsigned int length, CONST char *input,
		  CONST char *(*get_variable) (CONST char *variable,
					       void *info),
		  void *info, FILE *errfp) );
EXTERN_FUNCTION (const char *get_old_name,
		 (const char *devname, unsigned int namelen,
		  char *buffer, unsigned int major, unsigned int minor) );


/*  Public data  */
flag syslog_is_open = FALSE;


/*  Public functions  */
int mksymlink (const char *oldpath, const char *newpath);


/*  Private functions  */
static void setup_initial_entries ();
static void read_config (CONST char *location, flag optional,
			 unsigned long *event_mask);
static void read_config_file (CONST char *path, flag optional,