مساعدة في اتخطي الفوربدين

# Author: FuRty 
# Email : fir4t@fir4t.org 
# ***   : www.mykingdom.us 
# Greetz: RedGuard, Trsniper 
# Special Thanks : KnocKout and Inj3ct0r Team 
# Video : http://www.facebook.com/video/video.php?v=101428079927069 

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#define _GNU_SOURCE 

#include <stdio.h> 
#include <stdlib.h> 
#include <string.h> 
#include <ctype.h> 

#define KSYM_****_LEN        127 


struct sym_entry { 
    unsigned long long addr; 
    unsigned int len; 
    unsigned char *sym; 
}; 


static struct sym_entry *table; 
static unsigned int table_size, table_cnt; 
static unsigned long long _****, _s****, _e****, _sinit****, _einit****, _sextra****, _eextra****; 
static int all_symbols = 0; 
static char symbol_prefix_char = '\0'; 

int token_profit[0x10000]; 

/* the table that holds the result of the compression */ 
unsigned char best_table[256][2]; 
unsigned char best_table_len[256]; 


static void usage(void) 
{ 
    fprintf(stderr, "Usage: kallsyms [--all-symbols] [--symbol-prefix=<prefix char>] < in.map > out.S\n"); 
    exit(1); 
} 

/* 
 * This ignores the intensely annoying "mapping symbols" found 
 * in ARM ELF files: $a, $t and $d. 
 */ 
static inline int is_arm_mapping_symbol(const char *str) 
{ 
    return str[0] == '$' && strchr("atd", str[1]) 
           && (str[2] == '\0' || str[2] == '.'); 
} 

static int read_symbol(FILE *in, struct sym_entry *s) 
{ 
    char str[500]; 
    char *sym, stype; 
    int rc; 

    rc = fscanf(in, "%llx %c %499s\n", &s->addr, &stype, str); 
    if (rc != 3) { 
        if (rc != EOF) { 
            /* skip line */ 
            fgets(str, 500, in); 
        } 
        return -1; 
    } 

    sym = str; 
    /* skip prefix char */ 
    if (symbol_prefix_char && str[0] == symbol_prefix_char) 
        sym++; 

    /* Ignore most absolute/undefined (?) symbols. */ 
    if (strcmp(sym, "_****") == 0) 
        _**** = s->addr; 
    else if (strcmp(sym, "_s****") == 0) 
        _s**** = s->addr; 
    else if (strcmp(sym, "_e****") == 0) 
        _e**** = s->addr; 
    else if (strcmp(sym, "_sinit****") == 0) 
        _sinit**** = s->addr; 
    else if (strcmp(sym, "_einit****") == 0) 
        _einit**** = s->addr; 
    else if (strcmp(sym, "_sextra****") == 0) 
        _sextra**** = s->addr; 
    else if (strcmp(sym, "_eextra****") == 0) 
        _eextra**** = s->addr; 
    else if (toupper(stype) == 'A') 
    { 
        /* Keep these useful absolute symbols */ 
        if (strcmp(sym, "__kernel_syscall_via_break") && 
            strcmp(sym, "__kernel_syscall_via_epc") && 
            strcmp(sym, "__kernel_sigtramp") && 
            strcmp(sym, "__gp")) 
            return -1; 

    } 
    else if (toupper(stype) == 'U' || 
         is_arm_mapping_symbol(sym)) 
        return -1; 
    /* exclude also MIPS ELF local symbols ($L123 instead of .L123) */ 
    else if (str[0] == '$') 
        return -1; 

    /* include the type field in the symbol ****, so that it gets 
     * compressed together */ 
    s->len = strlen(str) + 1; 
    s->sym = malloc(s->len + 1); 
    if (!s->sym) { 
        fprintf(stderr, "kallsyms failure: " 
            "unable to allocate required amount of memory\n"); 
        exit(EXIT_FAILURE); 
    } 
    strcpy((char *)s->sym + 1, str); 
    s->sym[0] = stype; 

    return 0; 
} 

static int symbol_valid(struct sym_entry *s) 
{ 
    /* Symbols which vary between passes.  Passes 1 and 2 must have 
     * identical symbol lists.  The kallsyms_* symbols below are only added 
     * after pass 1, they would be included in pass 2 when --all-symbols is 
     * specified so exclude them to get a stable symbol list. 
     */ 
    static char *special_symbols[] = { 
        "kallsyms_addresses", 
        "kallsyms_num_syms", 
        "kallsyms_****s", 
        "kallsyms_markers", 
        "kallsyms_token_table", 
        "kallsyms_token_index", 

    /* Exclude linker generated symbols which vary between passes */ 
        "_SDA_BASE_",        /* ppc */ 
        "_SDA2_BASE_",        /* ppc */ 
        NULL }; 
    int i; 
    int offset = 1; 

    /* skip prefix char */ 
    if (symbol_prefix_char && *(s->sym + 1) == symbol_prefix_char) 
        offset++; 

    /* if --all-symbols is not specified, then symbols outside the **** 
     * and init**** sections are discarded */ 
    if (!all_symbols) { 
        if ((s->addr < _s**** || s->addr > _e****) 
            && (s->addr < _sinit**** || s->addr > _einit****) 
            && (s->addr < _sextra**** || s->addr > _eextra****)) 
            return 0; 
        /* Corner case.  Discard any symbols with the same value as 
         * _e**** _einit**** or _eextra****; they can move between pass 
         * 1 and 2 when the kallsyms data are added.  If these symbols 
         * move then they may get dropped in pass 2, which breaks the 
         * kallsyms rules. 
         */ 
        if ((s->addr == _e**** && strcmp((char*)s->sym + offset, "_e****")) || 
            (s->addr == _einit**** && strcmp((char*)s->sym + offset, "_einit****")) || 
            (s->addr == _eextra**** && strcmp((char*)s->sym + offset, "_eextra****"))) 
            return 0; 
    } 

    /* Exclude symbols which vary between passes. */ 
    if (strstr((char *)s->sym + offset, "_compiled.")) 
        return 0; 

    for (i = 0; special_symbols[i]; i++) 
        if( strcmp((char *)s->sym + offset, special_symbols[i]) == 0 ) 
            return 0; 

    return 1; 
} 

static void read_map(FILE *in) 
{ 
    while (!feof(in)) { 
        if (table_cnt >= table_size) { 
            table_size += 10000; 
            table = realloc(table, sizeof(*table) * table_size); 
            if (!table) { 
                fprintf(stderr, "out of memory\n"); 
                exit (1); 
            } 
        } 
        if (read_symbol(in, &table[table_cnt]) == 0) 
            table_cnt++; 
    } 
} 

static void output_label(char *label) 
{ 
    if (symbol_prefix_char) 
        printf(".globl %c%s\n", symbol_prefix_char, label); 
    else 
        printf(".globl %s\n", label); 
    printf("\tALGN\n"); 
    if (symbol_prefix_char) 
        printf("%c%s:\n", symbol_prefix_char, label); 
    else 
        printf("%s:\n", label); 
} 

/* uncompress a compressed symbol. When this function is called, the best table 
 * might still be compressed itself, so the function needs to be recursive */ 
static int expand_symbol(unsigned char *data, int len, char *result) 
{ 
    int c, rlen, total=0; 

    while (len) { 
        c = *data; 
        /* if the table holds a single char that is the same as the one 
         * we are looking for, then end the search */ 
        if (best_table[c][0]==c && best_table_len[c]==1) { 
            *result++ = c; 
            total++; 
        } else { 
            /* if not, recurse and expand */ 
            rlen = expand_symbol(best_table[c], best_table_len[c], result); 
            total += rlen; 
            result += rlen; 
        } 
        data++; 
        len--; 
    } 
    *result=0; 

    return total; 
} 

static void write_src(void) 
{ 
    unsigned int i, k, off; 
    unsigned int best_idx[256]; 
    unsigned int *markers; 
    char buf[KSYM_****_LEN+1]; 

    printf("#include <asm/types.h>\n"); 
    printf("#if BITS_PER_LONG == 64\n"); 
    printf("#define PTR .quad\n"); 
    printf("#define ALGN .align 8\n"); 
    printf("#else\n"); 
    printf("#define PTR .long\n"); 
    printf("#define ALGN .align 4\n"); 
    printf("#endif\n"); 

    printf(".data\n"); 

    /* Provide proper symbols relocatability by their '_****' 
     * relativeness.  The symbol ****s cannot be used to construct 
     * normal symbol references as the list of symbols contains 
     * symbols that are declared static and are private to their 
     * .o files.  This prevents .tmp_kallsyms.o or any other 
     * object from referencing them. 
     */ 
    output_label("kallsyms_addresses"); 
    for (i = 0; i < table_cnt; i++) { 
        if (toupper(table[i].sym[0]) != 'A') { 
            printf("\tPTR\t_**** + %#llx\n", 
                table[i].addr - _****); 
        } else { 
            printf("\tPTR\t%#llx\n", table[i].addr); 
        } 
    } 
    printf("\n"); 

    output_label("kallsyms_num_syms"); 
    printf("\tPTR\t%d\n", table_cnt); 
    printf("\n"); 

    /* table of offset markers, that give the offset in the compressed stream 
     * every 256 symbols */ 
    markers = malloc(sizeof(unsigned int) * ((table_cnt + 255) / 256)); 
    if (!markers) { 
        fprintf(stderr, "kallsyms failure: " 
            "unable to allocate required memory\n"); 
        exit(EXIT_FAILURE); 
    } 

    output_label("kallsyms_****s"); 
    off = 0; 
    for (i = 0; i < table_cnt; i++) { 
        if ((i & 0xFF) == 0) 
            markers[i >> 8] = off; 

        printf("\t.byte 0x%02x", table[i].len); 
        for (k = 0; k < table[i].len; k++) 
            printf(", 0x%02x", table[i].sym[k]); 
        printf("\n"); 

        off += table[i].len + 1; 
    } 
    printf("\n"); 

    output_label("kallsyms_markers"); 
    for (i = 0; i < ((table_cnt + 255) >> 8); i++) 
        printf("\tPTR\t%d\n", markers[i]); 
    printf("\n"); 

    free(markers); 

    output_label("kallsyms_token_table"); 
    off = 0; 
    for (i = 0; i < 256; i++) { 
        best_idx[i] = off; 
        expand_symbol(best_table[i], best_table_len[i], buf); 
        printf("\t.asciz\t\"%s\"\n", buf); 
        off += strlen(buf) + 1; 
    } 
    printf("\n"); 

    output_label("kallsyms_token_index"); 
    for (i = 0; i < 256; i++) 
        printf("\t.short\t%d\n", best_idx[i]); 
    printf("\n"); 
} 


/* table lookup compression functions */ 

/* count all the possible tokens in a symbol */ 
static void learn_symbol(unsigned char *symbol, int len) 
{ 
    int i; 

    for (i = 0; i < len - 1; i++) 
        token_profit[ symbol[i] + (symbol[i + 1] << 8) ]++; 
} 

/* decrease the count for all the possible tokens in a symbol */ 
static void forget_symbol(unsigned char *symbol, int len) 
{ 
    int i; 

    for (i = 0; i < len - 1; i++) 
        token_profit[ symbol[i] + (symbol[i + 1] << 8) ]--; 
} 

/* remove all the invalid symbols from the table and do the initial token count */ 
static void build_initial_tok_table(void) 
{ 
    unsigned int i, pos; 

    pos = 0; 
    for (i = 0; i < table_cnt; i++) { 
        if ( symbol_valid(&table[i]) ) { 
            if (pos != i) 
                table[pos] = table[i]; 
            learn_symbol(table[pos].sym, table[pos].len); 
            pos++; 
        } 
    } 
    table_cnt = pos; 
} 

/* replace a given token in all the valid symbols. Use the sampled symbols 
 * to update the counts */ 
static void compress_symbols(unsigned char *str, int idx) 
{ 
    unsigned int i, len, size; 
    unsigned char *p1, *p2; 

    for (i = 0; i < table_cnt; i++) { 

        len = table[i].len; 
        p1 = table[i].sym; 

        /* find the token on the symbol */ 
        p2 = memmem(p1, len, str, 2); 
        if (!p2) continue; 

        /* decrease the counts for this symbol's tokens */ 
        forget_symbol(table[i].sym, len); 

        size = len; 

        do { 
            *p2 = idx; 
            p2++; 
            size -= (p2 - p1); 
            memmove(p2, p2 + 1, size); 
            p1 = p2; 
            len--; 

            if (size < 2) break; 

            /* find the token on the symbol */ 
            p2 = memmem(p1, size, str, 2); 

        } while (p2); 

        table[i].len = len; 

        /* increase the counts for this symbol's new tokens */ 
        learn_symbol(table[i].sym, len); 
    } 
} 

/* search the token with the maximum profit */ 
static int find_best_token(void) 
{ 
    int i, best, bestprofit; 

    bestprofit=-10000; 
    best = 0; 

    for (i = 0; i < 0x10000; i++) { 
        if (token_profit[i] > bestprofit) { 
            best = i; 
            bestprofit = token_profit[i]; 
        } 
    } 
    return best; 
} 

/* this is the core of the algorithm: calculate the "best" table */ 
static void optimize_result(void) 
{ 
    int i, best; 

    /* using the '\0' symbol last allows compress_symbols to use standard 
     * fast string functions */ 
    for (i = 255; i >= 0; i--) { 

        /* if this table slot is empty (it is not used by an actual 
         * original char code */ 
        if (!best_table_len[i]) { 

            /* find the token with the breates profit value */ 
            best = find_best_token(); 

            /* place it in the "best" table */ 
            best_table_len[i] = 2; 
            best_table[i][0] = best & 0xFF; 
            best_table[i][1] = (best >> 8) & 0xFF; 

            /* replace this token in all the valid symbols */ 
            compress_symbols(best_table[i], i); 
        } 
    } 
} 

/* start by placing the symbols that are actually used on the table */ 
static void insert_real_symbols_in_table(void) 
{ 
    unsigned int i, j, c; 

    memset(best_table, 0, sizeof(best_table)); 
    memset(best_table_len, 0, sizeof(best_table_len)); 

    for (i = 0; i < table_cnt; i++) { 
        for (j = 0; j < table[i].len; j++) { 
            c = table[i].sym[j]; 
            best_table[c][0]=c; 
            best_table_len[c]=1; 
        } 
    } 
} 

static void optimize_token_table(void) 
{ 
    build_initial_tok_table(); 

    insert_real_symbols_in_table(); 

    /* When valid symbol is not registered, exit to error */ 
    if (!table_cnt) { 
        fprintf(stderr, "No valid symbol.\n"); 
        exit(1); 
    } 

    optimize_result(); 
} 


int main(int argc, char **argv) 
{ 
    if (argc >= 2) { 
        int i; 
        for (i = 1; i < argc; i++) { 
            if(strcmp(argv[i], "--all-symbols") == 0) 
                all_symbols = 1; 
            else if (strncmp(argv[i], "--symbol-prefix=", 16) == 0) { 
                char *p = &argv[i][16]; 
                /* skip quote */ 
                if ((*p == '"' && *(p+2) == '"') || (*p == '\'' && *(p+2) == '\'')) 
                    p++; 
                symbol_prefix_char = *p; 
            } else 
                usage(); 
        } 
    } else if (argc != 1) 
        usage(); 

    read_map(stdin); 
    optimize_token_table(); 
    write_src(); 

    return 0; 
}