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October 30, 2013 23:20
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Learn more about bidirectional Unicode charactersOriginal file line number Diff line number Diff line change @@ -0,0 +1,270 @@ /* This is a wrapper library that will give your server the power of * /dev/null as a service, as seen at http://devnull-as-a-service.com/ * * Compile: * gcc -ggdb -shared -fPIC dnaas.c -ldl -lcurl -o libdnaas.so * * Try: * LD_PRELOAD=./libdnaas.so dd if=/dev/sda of=/dev/null bs=8192 count=16 * * Install: * sudo cp libdnaas.so /usr/lib && echo /usr/lib/libdnaas.so | sudo tee -a /etc/ld.so.preload */ #define _GNU_SOURCE #include <stdio.h> #include <stdint.h> #include <stdarg.h> #include <stdlib.h> #include <unistd.h> #include <string.h> #include <tomcrypt.h> #include <curl/curl.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <dlfcn.h> #ifndef FD_MAX #define FD_MAX 65536 #endif #define DEV_NULL_URL "http://devnull-as-a-service.com/dev/null" static char _dnaas_loaded = 0; static char _dnaas_devnull[] = "/dev/null"; static FILE * (*_real_fopen)(const char *, const char *); static FILE * (*_real_freopen)(const char *, const char *, FILE *); static int (*_real_fclose)(FILE *); static int (*_real_open)(const char *, int, ...); static int (*_real_open64)(const char *, int, ...); static int (*_real_close)(int); static int (*_real_dup)(int); static int (*_real_dup2)(int, int); static int (*_real_dup3)(int, int, int); static ssize_t (*_real_write)(int, const void *, size_t); void _dnaas_load(); static char _dnaas_fd_tab[FD_MAX]; void _dnaas_load() { if (_real_fopen == NULL) _real_fopen = dlsym(RTLD_NEXT, "fopen"); if (_real_freopen == NULL) _real_freopen = dlsym(RTLD_NEXT, "freopen"); if (_real_fclose == NULL) _real_fclose = dlsym(RTLD_NEXT, "fclose"); if (_real_open == NULL) _real_open = dlsym(RTLD_NEXT, "open"); if (_real_open64 == NULL) _real_open64 = dlsym(RTLD_NEXT, "open64"); if (_real_close == NULL) _real_close = dlsym(RTLD_NEXT, "close"); if (_real_dup == NULL) _real_dup = dlsym(RTLD_NEXT, "dup"); if (_real_dup2 == NULL) _real_dup2 = dlsym(RTLD_NEXT, "dup2"); if (_real_dup3 == NULL) _real_dup3 = dlsym(RTLD_NEXT, "dup3"); if (_real_write == NULL) _real_write = dlsym(RTLD_NEXT, "write"); int i; for (i = 0; i < FD_MAX; i++) _dnaas_fd_tab[i] = 0; _dnaas_loaded = 1; /* curl calls functions we hook, so flip the bit here */ curl_global_init(CURL_GLOBAL_DEFAULT); } ssize_t write(int fd, const void *buf, size_t count) { if (_dnaas_loaded != 1) _dnaas_load(); if (_dnaas_fd_tab[fd]) { ssize_t ret = count; CURL *curl; CURLcode curl_res; struct curl_slist *headers=NULL; //fprintf(stderr, "intercepted write of %d bytes\n", (int)count); curl = curl_easy_init(); if (!curl) { fprintf(stderr, "Failed to start curl!\n"); return -1; } headers = curl_slist_append(headers, "Expect:"); headers = curl_slist_append(headers, "Content-Type: application/octet-stream"); curl_easy_setopt(curl, CURLOPT_URL, DEV_NULL_URL); curl_easy_setopt(curl, CURLOPT_POST, 1); curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers); curl_easy_setopt(curl, CURLOPT_POSTFIELDS, buf); curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, count); if ((curl_res = curl_easy_perform(curl)) != CURLE_OK) { fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(curl_res)); ret = -1; } curl_slist_free_all(headers); curl_easy_cleanup(curl); return ret; } //fprintf(stderr, "write passed through\n"); return _real_write(fd, buf, count); } int open(const char *path, int flags, ...) { va_list args; mode_t mode; va_start(args, flags); mode = va_arg(args, mode_t); va_end(args); if (_dnaas_loaded != 1) _dnaas_load(); int override = 0; if (strcmp(path, _dnaas_devnull) == 0) { path = _dnaas_devnull; override = 1; } int fd; fd = _real_open(path, flags, mode); _dnaas_fd_tab[fd] = override; return fd; } int open64(const char *path, int flags, ...) { va_list args; mode_t mode; va_start(args, flags); mode = va_arg(args, mode_t); va_end(args); if (_dnaas_loaded != 1) _dnaas_load(); int override = 0; if (strcmp(path, _dnaas_devnull) == 0) { path = _dnaas_devnull; override = 1; } int fd; fd = _real_open64(path, flags, mode); _dnaas_fd_tab[fd] = override; return fd; } int close(int fd) { if (_dnaas_loaded != 1) _dnaas_load(); _dnaas_fd_tab[fd] = 0; return _real_close(fd); } FILE * fopen(const char *path, const char *mode) { if (_dnaas_loaded != 1) _dnaas_load(); int override = 0; if (strcmp(path, _dnaas_devnull) == 0) { path = _dnaas_devnull; override = 1; } int fd; FILE *fstr; fstr = _real_fopen(path, mode); fd = fileno(fstr); _dnaas_fd_tab[fd] = override; return fstr; } FILE * freopen(const char *path, const char *mode, FILE *stream) { if (_dnaas_loaded != 1) _dnaas_load(); int override = 0; if (strcmp(path, _dnaas_devnull) == 0) { path = _dnaas_devnull; override = 1; } int fd; FILE *fstr; fd = fileno(stream); _dnaas_fd_tab[fd] = 0; fstr = _real_freopen(path, mode, stream); fd = fileno(fstr); _dnaas_fd_tab[fd] = override; return fstr; } int fclose(FILE *stream) { if (_dnaas_loaded != 1) _dnaas_load(); int fd; fd = fileno(stream); _dnaas_fd_tab[fd] = 0; return _real_fclose(stream); } int dup(int oldfd) { if (_dnaas_loaded != 1) _dnaas_load(); int override = _dnaas_fd_tab[oldfd]; _dnaas_fd_tab[oldfd] = 0; int fd; if ((fd = _real_dup(oldfd)) >= 0) _dnaas_fd_tab[fd] = override; return fd; } int dup2(int oldfd, int newfd) { if (_dnaas_loaded != 1) _dnaas_load(); int override = _dnaas_fd_tab[oldfd]; _dnaas_fd_tab[oldfd] = 0; int fd; if ((fd = _real_dup2(oldfd, newfd)) >= 0) _dnaas_fd_tab[fd] = override; return fd; } int dup3(int oldfd, int newfd, int flags) { if (_dnaas_loaded != 1) _dnaas_load(); int override = _dnaas_fd_tab[oldfd]; _dnaas_fd_tab[oldfd] = 0; int fd; if ((fd = _real_dup3(oldfd, newfd, flags)) >= 0) _dnaas_fd_tab[fd] = override; return fd; }