security: Add documentation

[Samba/gbeck.git] / source3 / smbd / mangle_hash.c

/*
   Unix SMB/CIFS implementation.
   Name mangling
   Copyright (C) Andrew Tridgell 1992-2002
   Copyright (C) Simo Sorce 2001
   Copyright (C) Andrew Bartlett 2002
   Copyright (C) Jeremy Allison 2007

   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 3 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, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"
#include "system/filesys.h"
#include "smbd/smbd.h"
#include "smbd/globals.h"
#include "mangle.h"
#include "util_tdb.h"
#include "lib/param/loadparm.h"

/* -------------------------------------------------------------------------- **
 * Other stuff...
 *
 * magic_char     - This is the magic char used for mangling.  It's
 *                  global.  There is a call to lp_magicchar() in server.c
 *                  that is used to override the initial value.
 *
 * MANGLE_BASE    - This is the number of characters we use for name mangling.
 *
 * basechars      - The set characters used for name mangling.  This
 *                  is static (scope is this file only).
 *
 * mangle()       - Macro used to select a character from basechars (i.e.,
 *                  mangle(n) will return the nth digit, modulo MANGLE_BASE).
 *
 * chartest       - array 0..255.  The index range is the set of all possible
 *                  values of a byte.  For each byte value, the content is a
 *                  two nibble pair.  See BASECHAR_MASK below.
 *
 * ct_initialized - False until the chartest array has been initialized via
 *                  a call to init_chartest().
 *
 * BASECHAR_MASK  - Masks the upper nibble of a one-byte value.
 *
 * isbasecahr()   - Given a character, check the chartest array to see
 *                  if that character is in the basechars set.  This is
 *                  faster than using strchr_m().
 *
 */

static const char basechars[43]="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_-!@#$%";
#define MANGLE_BASE       (sizeof(basechars)/sizeof(char)-1)

#define mangle(V) ((char)(basechars[(V) % MANGLE_BASE]))
#define BASECHAR_MASK 0xf0
#define isbasechar(C) ( (chartest[ ((C) & 0xff) ]) & BASECHAR_MASK )

/* -------------------------------------------------------------------- */


/*******************************************************************
 Determine if a character is valid in a 8.3 name.
********************************************************************/

/**
 * Load the valid character map table from <tt>valid.dat</tt> or
 * create from the configured codepage.
 *
 * This function is called whenever the configuration is reloaded.
 * However, the valid character table is not changed if it's loaded
 * from a file, because we can't unmap files.
 **/

static uint8 *valid_table;
static void init_valid_table(void)
{
        if (valid_table) {
                return;
        }

        valid_table = (uint8 *)map_file(data_path(talloc_tos(), "valid.dat"), 0x10000);
        if (!valid_table) {
                smb_panic("Could not load valid.dat file required for mangle method=hash");
                return;
        }
}

static bool isvalid83_w(smb_ucs2_t c)
{
        init_valid_table();
        return valid_table[SVAL(&c,0)] != 0;
}

static NTSTATUS has_valid_83_chars(const smb_ucs2_t *s, bool allow_wildcards)
{
        if (!*s) {
                return NT_STATUS_INVALID_PARAMETER;
        }

        if (!allow_wildcards && ms_has_wild_w(s)) {
                return NT_STATUS_UNSUCCESSFUL;
        }

        while (*s) {
                if(!isvalid83_w(*s)) {
                        return NT_STATUS_UNSUCCESSFUL;
                }
                s++;
        }

        return NT_STATUS_OK;
}

static NTSTATUS has_illegal_chars(const smb_ucs2_t *s, bool allow_wildcards)
{
        if (!allow_wildcards && ms_has_wild_w(s)) {
                return NT_STATUS_UNSUCCESSFUL;
        }

        while (*s) {
                if (*s <= 0x1f) {
                        /* Control characters. */
                        return NT_STATUS_UNSUCCESSFUL;
                }
                switch(*s) {
                        case UCS2_CHAR('\\'):
                        case UCS2_CHAR('/'):
                        case UCS2_CHAR('|'):
                        case UCS2_CHAR(':'):
                                return NT_STATUS_UNSUCCESSFUL;
                }
                s++;
        }

        return NT_STATUS_OK;
}

/*******************************************************************
 Duplicate string.
********************************************************************/

static smb_ucs2_t *strdup_w(const smb_ucs2_t *src)
{
        smb_ucs2_t *dest;
        size_t len = strlen_w(src);
        dest = SMB_MALLOC_ARRAY(smb_ucs2_t, len + 1);
        if (!dest) {
                DEBUG(0,("strdup_w: out of memory!\n"));
                return NULL;
        }

        memcpy(dest, src, len * sizeof(smb_ucs2_t));
        dest[len] = 0;
        return dest;
}

/* return False if something fail and
 * return 2 alloced unicode strings that contain prefix and extension
 */

static NTSTATUS mangle_get_prefix(const smb_ucs2_t *ucs2_string, smb_ucs2_t **prefix,
                smb_ucs2_t **extension, bool allow_wildcards)
{
        size_t ext_len;
        smb_ucs2_t *p;

        *extension = 0;
        *prefix = strdup_w(ucs2_string);
        if (!*prefix) {
                return NT_STATUS_NO_MEMORY;
        }
        if ((p = strrchr_w(*prefix, UCS2_CHAR('.')))) {
                ext_len = strlen_w(p+1);
                if ((ext_len > 0) && (ext_len < 4) && (p != *prefix) &&
                    (NT_STATUS_IS_OK(has_valid_83_chars(p+1,allow_wildcards)))) /* check extension */ {
                        *p = 0;
                        *extension = strdup_w(p+1);
                        if (!*extension) {
                                SAFE_FREE(*prefix);
                                return NT_STATUS_NO_MEMORY;
                        }
                }
        }
        return NT_STATUS_OK;
}

/* ************************************************************************** **
 * Return NT_STATUS_UNSUCCESSFUL if a name is a special msdos reserved name.
 * or contains illegal characters.
 *
 *  Input:  fname - String containing the name to be tested.
 *
 *  Output: NT_STATUS_UNSUCCESSFUL, if the condition above is true.
 *
 *  Notes:  This is a static function called by is_8_3(), below.
 *
 * ************************************************************************** **
 */

static NTSTATUS is_valid_name(const smb_ucs2_t *fname, bool allow_wildcards, bool only_8_3)
{
        smb_ucs2_t *str, *p;
        size_t num_ucs2_chars;
        NTSTATUS ret = NT_STATUS_OK;

        if (!fname || !*fname)
                return NT_STATUS_INVALID_PARAMETER;

        /* . and .. are valid names. */
        if (strcmp_wa(fname, ".")==0 || strcmp_wa(fname, "..")==0)
                return NT_STATUS_OK;

        if (only_8_3) {
                ret = has_valid_83_chars(fname, allow_wildcards);
                if (!NT_STATUS_IS_OK(ret))
                        return ret;
        }

        ret = has_illegal_chars(fname, allow_wildcards);
        if (!NT_STATUS_IS_OK(ret))
                return ret;

        /* Name can't end in '.' or ' ' */
        num_ucs2_chars = strlen_w(fname);
        if (fname[num_ucs2_chars-1] == UCS2_CHAR('.') || fname[num_ucs2_chars-1] == UCS2_CHAR(' ')) {
                return NT_STATUS_UNSUCCESSFUL;
        }

        str = strdup_w(fname);

        /* Truncate copy after the first dot. */
        p = strchr_w(str, UCS2_CHAR('.'));
        if (p) {
                *p = 0;
        }

        strupper_w(str);
        p = &str[1];

        switch(str[0])
        {
        case UCS2_CHAR('A'):
                if(strcmp_wa(p, "UX") == 0)
                        ret = NT_STATUS_UNSUCCESSFUL;
                break;
        case UCS2_CHAR('C'):
                if((strcmp_wa(p, "LOCK$") == 0)
                || (strcmp_wa(p, "ON") == 0)
                || (strcmp_wa(p, "OM1") == 0)
                || (strcmp_wa(p, "OM2") == 0)
                || (strcmp_wa(p, "OM3") == 0)
                || (strcmp_wa(p, "OM4") == 0)
                )
                        ret = NT_STATUS_UNSUCCESSFUL;
                break;
        case UCS2_CHAR('L'):
                if((strcmp_wa(p, "PT1") == 0)
                || (strcmp_wa(p, "PT2") == 0)
                || (strcmp_wa(p, "PT3") == 0)
                )
                        ret = NT_STATUS_UNSUCCESSFUL;
                break;
        case UCS2_CHAR('N'):
                if(strcmp_wa(p, "UL") == 0)
                        ret = NT_STATUS_UNSUCCESSFUL;
                break;
        case UCS2_CHAR('P'):
                if(strcmp_wa(p, "RN") == 0)
                        ret = NT_STATUS_UNSUCCESSFUL;
                break;
        default:
                break;
        }

        SAFE_FREE(str);
        return ret;
}

static NTSTATUS is_8_3_w(const smb_ucs2_t *fname, bool allow_wildcards)
{
        smb_ucs2_t *pref = 0, *ext = 0;
        size_t plen;
        NTSTATUS ret = NT_STATUS_UNSUCCESSFUL;

        if (!fname || !*fname)
                return NT_STATUS_INVALID_PARAMETER;

        if (strlen_w(fname) > 12)
                return NT_STATUS_UNSUCCESSFUL;

        if (strcmp_wa(fname, ".") == 0 || strcmp_wa(fname, "..") == 0)
                return NT_STATUS_OK;

        /* Name cannot start with '.' */
        if (*fname == UCS2_CHAR('.'))
                return NT_STATUS_UNSUCCESSFUL;

        if (!NT_STATUS_IS_OK(is_valid_name(fname, allow_wildcards, True)))
                goto done;

        if (!NT_STATUS_IS_OK(mangle_get_prefix(fname, &pref, &ext, allow_wildcards)))
                goto done;
        plen = strlen_w(pref);

        if (strchr_wa(pref, '.'))
                goto done;
        if (plen < 1 || plen > 8)
                goto done;
        if (ext && (strlen_w(ext) > 3))
                goto done;

        ret = NT_STATUS_OK;

done:
        SAFE_FREE(pref);
        SAFE_FREE(ext);
        return ret;
}

static bool is_8_3(const char *fname, bool check_case, bool allow_wildcards,
                   const struct share_params *p)
{
        const char *f;
        smb_ucs2_t *ucs2name;
        NTSTATUS ret = NT_STATUS_UNSUCCESSFUL;
        size_t size;

        if (!fname || !*fname)
                return False;
        if ((f = strrchr(fname, '/')) == NULL)
                f = fname;
        else
                f++;

        if (strlen(f) > 12)
                return False;

        if (!push_ucs2_talloc(NULL, &ucs2name, f, &size)) {
                DEBUG(0,("is_8_3: internal error push_ucs2_talloc() failed!\n"));
                goto done;
        }

        ret = is_8_3_w(ucs2name, allow_wildcards);

done:
        TALLOC_FREE(ucs2name);

        if (!NT_STATUS_IS_OK(ret)) {
                return False;
        }

        return True;
}

/* -------------------------------------------------------------------------- **
 * Functions...
 */

/* ************************************************************************** **
 * Initialize the static character test array.
 *
 *  Input:  none
 *
 *  Output: none
 *
 *  Notes:  This function changes (loads) the contents of the <chartest>
 *          array.  The scope of <chartest> is this file.
 *
 * ************************************************************************** **
 */

static void init_chartest( void )
{
        const unsigned char *s;

        chartest = SMB_MALLOC_ARRAY(unsigned char, 256);

        SMB_ASSERT(chartest != NULL);
        memset(chartest, '\0', 256);

        for( s = (const unsigned char *)basechars; *s; s++ ) {
                chartest[*s] |= BASECHAR_MASK;
        }
}

/* ************************************************************************** **
 * Return True if the name *could be* a mangled name.
 *
 *  Input:  s - A path name - in UNIX pathname format.
 *
 *  Output: True if the name matches the pattern described below in the
 *          notes, else False.
 *
 *  Notes:  The input name is *not* tested for 8.3 compliance.  This must be
 *          done separately.  This function returns true if the name contains
 *          a magic character followed by excactly two characters from the
 *          basechars list (above), which in turn are followed either by the
 *          nul (end of string) byte or a dot (extension) or by a '/' (end of
 *          a directory name).
 *
 * ************************************************************************** **
 */

static bool is_mangled(const char *s, const struct share_params *p)
{
        char *magic;
        char magic_char;

        magic_char = lp_magicchar(p);

        if (chartest == NULL) {
                init_chartest();
        }

        magic = strchr_m( s, magic_char );
        while( magic && magic[1] && magic[2] ) {         /* 3 chars, 1st is magic. */
                if( ('.' == magic[3] || '/' == magic[3] || !(magic[3]))          /* Ends with '.' or nul or '/' ?  */
                                && isbasechar( toupper_m(magic[1]) )           /* is 2nd char basechar?  */
                                && isbasechar( toupper_m(magic[2]) ) )         /* is 3rd char basechar?  */
                        return( True );                           /* If all above, then true, */
                magic = strchr_m( magic+1, magic_char );      /*    else seek next magic. */
        }
        return( False );
}

/***************************************************************************
 Initializes or clears the mangled cache.
***************************************************************************/

static void mangle_reset( void )
{
        /* We could close and re-open the tdb here... should we ? The old code did
           the equivalent... JRA. */
}

/***************************************************************************
 Add a mangled name into the cache.
 If the extension of the raw name maps directly to the
 extension of the mangled name, then we'll store both names
 *without* extensions.  That way, we can provide consistent
 reverse mangling for all names that match.  The test here is
 a bit more careful than the one done in earlier versions of
 mangle.c:

    - the extension must exist on the raw name,
    - it must be all lower case
    - it must match the mangled extension (to prove that no
      mangling occurred).
  crh 07-Apr-1998
**************************************************************************/

static void cache_mangled_name( const char mangled_name[13],
                                const char *raw_name )
{
        TDB_DATA data_val;
        char mangled_name_key[13];
        char *s1 = NULL;
        char *s2 = NULL;

        /* If the cache isn't initialized, give up. */
        if( !tdb_mangled_cache )
                return;

        /* Init the string lengths. */
        strlcpy(mangled_name_key, mangled_name, sizeof(mangled_name_key));

        /* See if the extensions are unmangled.  If so, store the entry
         * without the extension, thus creating a "group" reverse map.
         */
        s1 = strrchr( mangled_name_key, '.' );
        if( s1 && (s2 = strrchr( raw_name, '.' )) ) {
                size_t i = 1;
                while( s1[i] && (tolower_m( s1[i] ) == s2[i]) )
                        i++;
                if( !s1[i] && !s2[i] ) {
                        /* Truncate at the '.' */
                        *s1 = '\0';
                        /*
                         * DANGER WILL ROBINSON - this
                         * is changing a const string via
                         * an aliased pointer ! Remember to
                         * put it back once we've used it.
                         * JRA
                         */
                        *s2 = '\0';
                }
        }

        /* Allocate a new cache entry.  If the allocation fails, just return. */
        data_val = string_term_tdb_data(raw_name);
        if (tdb_store_bystring(tdb_mangled_cache, mangled_name_key, data_val, TDB_REPLACE) != 0) {
                DEBUG(0,("cache_mangled_name: Error storing entry %s -> %s\n", mangled_name_key, raw_name));
        } else {
                DEBUG(5,("cache_mangled_name: Stored entry %s -> %s\n", mangled_name_key, raw_name));
        }
        /* Restore the change we made to the const string. */
        if (s2) {
                *s2 = '.';
        }
}

/* ************************************************************************** **
 * Check for a name on the mangled name stack
 *
 *  Input:  s - Input *and* output string buffer.
 *          maxlen - space in i/o string buffer.
 *  Output: True if the name was found in the cache, else False.
 *
 *  Notes:  If a reverse map is found, the function will overwrite the string
 *          space indicated by the input pointer <s>.  This is frightening.
 *          It should be rewritten to return NULL if the long name was not
 *          found, and a pointer to the long name if it was found.
 *
 * ************************************************************************** **
 */

static bool lookup_name_from_8_3(TALLOC_CTX *ctx,
                                const char *in,
                                char **out, /* talloced on the given context. */
                                const struct share_params *p)
{
        TDB_DATA data_val;
        char *saved_ext = NULL;
        char *s = talloc_strdup(ctx, in);

        /* If the cache isn't initialized, give up. */
        if(!s || !tdb_mangled_cache ) {
                TALLOC_FREE(s);
                return False;
        }

        data_val = tdb_fetch_bystring(tdb_mangled_cache, s);

        /* If we didn't find the name *with* the extension, try without. */
        if(data_val.dptr == NULL || data_val.dsize == 0) {
                char *ext_start = strrchr( s, '.' );
                if( ext_start ) {
                        if((saved_ext = talloc_strdup(ctx,ext_start)) == NULL) {
                                TALLOC_FREE(s);
                                return False;
                        }

                        *ext_start = '\0';
                        data_val = tdb_fetch_bystring(tdb_mangled_cache, s);
                        /*
                         * At this point s is the name without the
                         * extension. We re-add the extension if saved_ext
                         * is not null, before freeing saved_ext.
                         */
                }
        }

        /* Okay, if we haven't found it we're done. */
        if(data_val.dptr == NULL || data_val.dsize == 0) {
                TALLOC_FREE(saved_ext);
                TALLOC_FREE(s);
                return False;
        }

        /* If we *did* find it, we need to talloc it on the given ctx. */
        if (saved_ext) {
                *out = talloc_asprintf(ctx, "%s%s",
                                        (char *)data_val.dptr,
                                        saved_ext);
        } else {
                *out = talloc_strdup(ctx, (char *)data_val.dptr);
        }

        TALLOC_FREE(s);
        TALLOC_FREE(saved_ext);
        SAFE_FREE(data_val.dptr);

        return *out ? True : False;
}

/**
 Check if a string is in "normal" case.
**/

static bool strisnormal(const char *s, int case_default)
{
        if (case_default == CASE_UPPER)
                return(!strhaslower(s));

        return(!strhasupper(s));
}


/*****************************************************************************
 Do the actual mangling to 8.3 format.
*****************************************************************************/

static bool to_8_3(char magic_char, const char *in, char out[13], int default_case)
{
        int csum;
        char *p;
        char extension[4];
        char base[9];
        int baselen = 0;
        int extlen = 0;
        char *s = SMB_STRDUP(in);

        extension[0] = 0;
        base[0] = 0;

        if (!s) {
                return False;
        }

        p = strrchr(s,'.');
        if( p && (strlen(p+1) < (size_t)4) ) {
                bool all_normal = ( strisnormal(p+1, default_case) ); /* XXXXXXXXX */

                if( all_normal && p[1] != 0 ) {
                        *p = 0;
                        csum = str_checksum( s );
                        *p = '.';
                } else
                        csum = str_checksum(s);
        } else
                csum = str_checksum(s);

        if (!strupper_m( s )) {
                SAFE_FREE(s);
                return false;
        }

        if( p ) {
                if( p == s )
                        strlcpy( extension, "___", 4);
                else {
                        *p++ = 0;
                        while( *p && extlen < 3 ) {
                                if ( *p != '.') {
                                        extension[extlen++] = p[0];
                                }
                                p++;
                        }
                        extension[extlen] = 0;
                }
        }

        p = s;

        while( *p && baselen < 5 ) {
                if (isbasechar(*p)) {
                        base[baselen++] = p[0];
                }
                p++;
        }
        base[baselen] = 0;

        csum = csum % (MANGLE_BASE*MANGLE_BASE);

        memcpy(out, base, baselen);
        out[baselen] = magic_char;
        out[baselen+1] = mangle( csum/MANGLE_BASE );
        out[baselen+2] = mangle( csum );

        if( *extension ) {
                out[baselen+3] = '.';
                strlcpy(&out[baselen+4], extension, 4);
        }

        SAFE_FREE(s);
        return True;
}

static bool must_mangle(const char *name,
                        const struct share_params *p)
{
        smb_ucs2_t *name_ucs2 = NULL;
        NTSTATUS status;
        size_t converted_size;

        if (!push_ucs2_talloc(NULL, &name_ucs2, name, &converted_size)) {
                DEBUG(0, ("push_ucs2_talloc failed!\n"));
                return False;
        }
        status = is_valid_name(name_ucs2, False, False);
        TALLOC_FREE(name_ucs2);
        /* We return true if we *must* mangle, so if it's
         * a valid name (status == OK) then we must return
         * false. Bug #6939. */
        return !NT_STATUS_IS_OK(status);
}

/*****************************************************************************
 * Convert a filename to DOS format.  Return True if successful.
 *  Input:  in        Incoming name.
 *
 *          out       8.3 DOS name.
 *
 *          cache83 - If False, the mangled name cache will not be updated.
 *                    This is usually used to prevent that we overwrite
 *                    a conflicting cache entry prematurely, i.e. before
 *                    we know whether the client is really interested in the
 *                    current name.  (See PR#13758).  UKD.
 *
 * ****************************************************************************
 */

static bool hash_name_to_8_3(const char *in,
                        char out[13],
                        bool cache83,
                        int default_case,
                        const struct share_params *p)
{
        smb_ucs2_t *in_ucs2 = NULL;
        size_t converted_size;
        char magic_char;

        magic_char = lp_magicchar(p);

        DEBUG(5,("hash_name_to_8_3( %s, cache83 = %s)\n", in,
                 cache83 ? "True" : "False"));

        if (!push_ucs2_talloc(NULL, &in_ucs2, in, &converted_size)) {
                DEBUG(0, ("push_ucs2_talloc failed!\n"));
                return False;
        }

        /* If it's already 8.3, just copy. */
        if (NT_STATUS_IS_OK(is_valid_name(in_ucs2, False, False)) &&
                                NT_STATUS_IS_OK(is_8_3_w(in_ucs2, False))) {
                TALLOC_FREE(in_ucs2);
                strlcpy(out, in, 13);
                return True;
        }

        TALLOC_FREE(in_ucs2);
        if (!to_8_3(magic_char, in, out, default_case)) {
                return False;
        }

        cache_mangled_name(out, in);

        DEBUG(5,("hash_name_to_8_3(%s) ==> [%s]\n", in, out));
        return True;
}

/*
  the following provides the abstraction layer to make it easier
  to drop in an alternative mangling implementation
*/
static const struct mangle_fns mangle_hash_fns = {
        mangle_reset,
        is_mangled,
        must_mangle,
        is_8_3,
        lookup_name_from_8_3,
        hash_name_to_8_3
};

/* return the methods for this mangling implementation */
const struct mangle_fns *mangle_hash_init(void)
{
        mangle_reset();

        /* Create the in-memory tdb using our custom hash function. */
        tdb_mangled_cache = tdb_open_ex("mangled_cache", 1031, TDB_INTERNAL,
                                (O_RDWR|O_CREAT), 0644, NULL, fast_string_hash);

        return &mangle_hash_fns;
}