diff options
Diffstat (limited to 'src/lib/fs/path.c')
| -rw-r--r-- | src/lib/fs/path.c | 432 |
1 files changed, 423 insertions, 9 deletions
diff --git a/src/lib/fs/path.c b/src/lib/fs/path.c index b3ef61979d..81960bd69a 100644 --- a/src/lib/fs/path.c +++ b/src/lib/fs/path.c @@ -1,6 +1,6 @@ /* Copyright (c) 2003, Roger Dingledine * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson. - * Copyright (c) 2007-2019, The Tor Project, Inc. */ + * Copyright (c) 2007-2020, The Tor Project, Inc. */ /* See LICENSE for licensing information */ /** @@ -13,15 +13,34 @@ #include "lib/malloc/malloc.h" #include "lib/log/log.h" #include "lib/log/util_bug.h" +#include "lib/container/smartlist.h" +#include "lib/sandbox/sandbox.h" #include "lib/string/printf.h" #include "lib/string/util_string.h" #include "lib/string/compat_ctype.h" +#include "lib/string/compat_string.h" +#include "lib/fs/files.h" +#include "lib/fs/dir.h" #include "lib/fs/userdb.h" +#ifdef HAVE_SYS_TYPES_H +#include <sys/types.h> +#endif +#ifdef HAVE_SYS_STAT_H +#include <sys/stat.h> +#endif #ifdef HAVE_UNISTD_H #include <unistd.h> #endif +#ifdef _WIN32 +#include <windows.h> +#include <shlwapi.h> +#else /* !(defined(_WIN32)) */ +#include <dirent.h> +#include <glob.h> +#endif /* defined(_WIN32) */ + #include <errno.h> #include <string.h> @@ -72,7 +91,7 @@ expand_filename(const char *filename) * Chapter+3.+Input+Validation/3.7+Validating+Filenames+and+Paths/ */ return tor_strdup(filename); -#else /* !(defined(_WIN32)) */ +#else /* !defined(_WIN32) */ if (*filename == '~') { char *home, *result=NULL; const char *rest; @@ -102,7 +121,7 @@ expand_filename(const char *filename) } tor_free(username); rest = slash ? (slash+1) : ""; -#else /* !(defined(HAVE_PWD_H)) */ +#else /* !defined(HAVE_PWD_H) */ log_warn(LD_CONFIG, "Couldn't expand homedir on system without pwd.h"); return tor_strdup(filename); #endif /* defined(HAVE_PWD_H) */ @@ -153,7 +172,7 @@ clean_fname_for_stat(char *name) return; name[len-1]='\0'; } -#else /* !(defined(_WIN32)) */ +#else /* !defined(_WIN32) */ (void)name; #endif /* defined(_WIN32) */ } @@ -161,7 +180,7 @@ clean_fname_for_stat(char *name) /** Modify <b>fname</b> to contain the name of its parent directory. Doesn't * actually examine the filesystem; does a purely syntactic modification. * - * The parent of the root director is considered to be iteself. + * The parent of the root director is considered to be itself. * * Path separators are the forward slash (/) everywhere and additionally * the backslash (\) on Win32. @@ -233,7 +252,7 @@ alloc_getcwd(void) raw_free(cwd); // alias for free to avoid tripping check-spaces. } return result; -#else /* !(defined(HAVE_GET_CURRENT_DIR_NAME)) */ +#else /* !defined(HAVE_GET_CURRENT_DIR_NAME) */ size_t size = 1024; char *buf = NULL; char *ptr = NULL; @@ -255,9 +274,10 @@ alloc_getcwd(void) #endif /* !defined(_WIN32) */ /** Expand possibly relative path <b>fname</b> to an absolute path. - * Return a newly allocated string, possibly equal to <b>fname</b>. */ + * Return a newly allocated string, which may be a duplicate of <b>fname</b>. + */ char * -make_path_absolute(char *fname) +make_path_absolute(const char *fname) { #ifdef _WIN32 char *absfname_malloced = _fullpath(NULL, fname, 1); @@ -268,7 +288,7 @@ make_path_absolute(char *fname) if (absfname_malloced) raw_free(absfname_malloced); return absfname; -#else /* !(defined(_WIN32)) */ +#else /* !defined(_WIN32) */ char *absfname = NULL, *path = NULL; tor_assert(fname); @@ -293,3 +313,397 @@ make_path_absolute(char *fname) return absfname; #endif /* defined(_WIN32) */ } + +/* The code below implements tor_glob and get_glob_opened_files. Because it is + * not easy to understand it by looking at individual functions, the big + * picture explanation here should be read first. + * + * Purpose of the functions: + * - tor_glob - receives a pattern and returns all the paths that result from + * its glob expansion, globs can be present on all path components. + * - get_glob_opened_files - receives a pattern and returns all the paths that + * are opened during its expansion (the paths before any path fragment that + * contains a glob as they have to be opened to check for glob matches). This + * is used to get the paths that have to be added to the seccomp sandbox + * allowed list. + * + * Due to OS API differences explained below, the implementation of tor_glob is + * completely different for Windows and POSIX systems, so we ended up with + * three different implementations: + * - tor_glob for POSIX - as POSIX glob does everything we need, we simply call + * it and process the results. This is completely implemented in tor_glob. + * - tor_glob for WIN32 - because the WIN32 API only supports expanding globs + * in the last path fragment, we need to expand the globs in each path + * fragment manually and call recursively to get the same behaviour as POSIX + * glob. When there are no globs in pattern, we know we are on the last path + * fragment and collect the full path. + * - get_glob_opened_files - because the paths before any path fragment with a + * glob will be opened to check for matches, we need to collect them and we + * need to expand the globs in each path fragments and call recursively until + * we find no more globs. + * + * As seen from the description above, both tor_glob for WIN32 and + * get_glob_opened_files receive a pattern and return a list of paths and have + * to expand all path fragments that contain globs and call themselves + * recursively. The differences are: + * - get_glob_opened_files collects paths before path fragments with globs + * while tor_glob for WIN32 collects full paths resulting from the expansion + * of all globs. + * - get_glob_opened_files can call tor_glob to expand path fragments with + * globs while tor_glob for WIN32 cannot because it IS tor_glob. For tor_glob + * for WIN32, an auxiliary function has to be used for this purpose. + * + * To avoid code duplication, the logic of tor_glob for WIN32 and + * get_glob_opened_files is implemented in get_glob_paths. The differences are + * configured by the extra function parameters: + * - final - if true, returns a list of paths obtained from expanding pattern + * (implements tor_glob). Otherwise, returns the paths before path fragments + * with globs (implements get_glob_opened_files). + * - unglob - function used to expand a path fragment. The function signature + * is defined by the unglob_fn typedef. Two implementations are available: + * - unglob_win32 - uses tor_listdir and PathMatchSpec (for tor_glob WIN32) + * - unglob_opened_files - uses tor_glob (for get_glob_opened_files) + */ + +/** Returns true if the character at position <b>pos</b> in <b>pattern</b> is + * considered a glob. Returns false otherwise. Takes escaping into account on + * systems where escaping globs is supported. */ +static inline bool +is_glob_char(const char *pattern, int pos) +{ + bool is_glob = pattern[pos] == '*' || pattern[pos] == '?'; +#ifdef _WIN32 + return is_glob; +#else /* !defined(_WIN32) */ + bool is_escaped = pos > 0 && pattern[pos-1] == '\\'; + return is_glob && !is_escaped; +#endif /* defined(_WIN32) */ +} + +/** Expands the first path fragment of <b>pattern</b> that contains globs. The + * path fragment is between <b>prev_sep</b> and <b>next_sep</b>. If the path + * fragment is the last fragment of <b>pattern</b>, <b>next_sep</b> will be the + * index of the last char. Returns a list of paths resulting from the glob + * expansion of the path fragment. Anything after <b>next_sep</b> is not + * included in the returned list. Returns NULL on failure. */ +typedef struct smartlist_t * unglob_fn(const char *pattern, int prev_sep, + int next_sep); + +/** Adds <b>path</b> to <b>result</b> if it exists and is a file type we can + * handle. Returns false if <b>path</b> is a file type we cannot handle, + * returns true otherwise. Used on tor_glob for WIN32. */ +static bool +add_non_glob_path(const char *path, struct smartlist_t *result) +{ + file_status_t file_type = file_status(path); + if (file_type == FN_ERROR) { + return false; + } else if (file_type != FN_NOENT) { + char *to_add = tor_strdup(path); + clean_fname_for_stat(to_add); + smartlist_add(result, to_add); + } + /* If WIN32 tor_glob is called with a non-existing path, we want it to + * return an empty list instead of error to match the regular version */ + return true; +} + +/** Auxiliary function used by get_glob_opened_files and WIN32 tor_glob. + * Returns a list of paths obtained from <b>pattern</b> using <b>unglob</b> to + * expand each path fragment. If <b>final</b> is true, the paths are the result + * of the glob expansion of <b>pattern</b> (implements tor_glob). Otherwise, + * the paths are the paths opened by glob while expanding <b>pattern</b> + * (implements get_glob_opened_files). Returns NULL on failure. */ +static struct smartlist_t * +get_glob_paths(const char *pattern, unglob_fn unglob, bool final) +{ + smartlist_t *result = smartlist_new(); + int i, prev_sep = -1, next_sep = -1; + bool is_glob = false, error_found = false, is_sep = false, is_last = false; + + // find first path fragment with globs + for (i = 0; pattern[i]; i++) { + is_glob = is_glob || is_glob_char(pattern, i); + is_last = !pattern[i+1]; + is_sep = pattern[i] == *PATH_SEPARATOR || pattern[i] == '/'; + if (is_sep || is_last) { + prev_sep = next_sep; + next_sep = i; // next_sep+1 is start of next fragment or end of string + if (is_glob) { + break; + } + } + } + + if (!is_glob) { // pattern fully expanded or no glob in pattern + if (final && !add_non_glob_path(pattern, result)) { + error_found = true; + goto end; + } + return result; + } + + if (!final) { + // add path before the glob to result + int len = prev_sep < 1 ? prev_sep + 1 : prev_sep; // handle /* + char *path_until_glob = tor_strndup(pattern, len); + smartlist_add(result, path_until_glob); + } + + smartlist_t *unglobbed_paths = unglob(pattern, prev_sep, next_sep); + if (!unglobbed_paths) { + error_found = true; + } else { + // for each path for current fragment, add the rest of the pattern + // and call recursively to get all expanded paths + SMARTLIST_FOREACH_BEGIN(unglobbed_paths, char *, current_path) { + char *next_path; + tor_asprintf(&next_path, "%s"PATH_SEPARATOR"%s", current_path, + &pattern[next_sep+1]); + smartlist_t *opened_next = get_glob_paths(next_path, unglob, final); + tor_free(next_path); + if (!opened_next) { + error_found = true; + break; + } + smartlist_add_all(result, opened_next); + smartlist_free(opened_next); + } SMARTLIST_FOREACH_END(current_path); + SMARTLIST_FOREACH(unglobbed_paths, char *, p, tor_free(p)); + smartlist_free(unglobbed_paths); + } + +end: + if (error_found) { + SMARTLIST_FOREACH(result, char *, p, tor_free(p)); + smartlist_free(result); + result = NULL; + } + return result; +} + +#ifdef _WIN32 +/** Expands globs in <b>pattern</b> for the path fragment between + * <b>prev_sep</b> and <b>next_sep</b> using the WIN32 API. Returns NULL on + * failure. Used by the WIN32 implementation of tor_glob. Implements unglob_fn, + * see its description for more details. */ +static struct smartlist_t * +unglob_win32(const char *pattern, int prev_sep, int next_sep) +{ + smartlist_t *result = smartlist_new(); + int len = prev_sep < 1 ? prev_sep + 1 : prev_sep; // handle /* + char *path_until_glob = tor_strndup(pattern, len); + + if (!is_file(file_status(path_until_glob))) { + smartlist_t *filenames = tor_listdir(path_until_glob); + if (!filenames) { + smartlist_free(result); + result = NULL; + } else { + SMARTLIST_FOREACH_BEGIN(filenames, char *, filename) { + TCHAR tpattern[MAX_PATH] = {0}; + TCHAR tfile[MAX_PATH] = {0}; + char *full_path; + tor_asprintf(&full_path, "%s"PATH_SEPARATOR"%s", + path_until_glob, filename); + char *path_curr_glob = tor_strndup(pattern, next_sep + 1); + // *\ must return only dirs, remove \ from the pattern so it matches + if (is_dir(file_status(full_path))) { + clean_fname_for_stat(path_curr_glob); + } +#ifdef UNICODE + mbstowcs(tpattern, path_curr_glob, MAX_PATH); + mbstowcs(tfile, full_path, MAX_PATH); +#else /* !defined(UNICODE) */ + strlcpy(tpattern, path_curr_glob, MAX_PATH); + strlcpy(tfile, full_path, MAX_PATH); +#endif /* defined(UNICODE) */ + if (PathMatchSpec(tfile, tpattern)) { + smartlist_add(result, full_path); + } else { + tor_free(full_path); + } + tor_free(path_curr_glob); + } SMARTLIST_FOREACH_END(filename); + SMARTLIST_FOREACH(filenames, char *, p, tor_free(p)); + smartlist_free(filenames); + } + } + tor_free(path_until_glob); + return result; +} +#elif HAVE_GLOB +/** Same as opendir but calls sandbox_intern_string before */ +static DIR * +prot_opendir(const char *name) +{ + if (sandbox_interned_string_is_missing(name)) { + errno = EPERM; + return NULL; + } + return opendir(sandbox_intern_string(name)); +} + +/** Same as stat but calls sandbox_intern_string before */ +static int +prot_stat(const char *pathname, struct stat *buf) +{ + if (sandbox_interned_string_is_missing(pathname)) { + errno = EPERM; + return -1; + } + return stat(sandbox_intern_string(pathname), buf); +} + +/** Same as lstat but calls sandbox_intern_string before */ +static int +prot_lstat(const char *pathname, struct stat *buf) +{ + if (sandbox_interned_string_is_missing(pathname)) { + errno = EPERM; + return -1; + } + return lstat(sandbox_intern_string(pathname), buf); +} +/** As closedir, but has the right type for gl_closedir */ +static void +wrap_closedir(void *arg) +{ + closedir(arg); +} + +/** Function passed to glob to handle processing errors. <b>epath</b> is the + * path that caused the error and <b>eerrno</b> is the errno set by the + * function that failed. We want to ignore ENOENT and ENOTDIR because, in BSD + * systems, these are not ignored automatically, which makes glob fail when + * globs expand to non-existing paths and GLOB_ERR is set. + */ +static int +glob_errfunc(const char *epath, int eerrno) +{ + (void)epath; + return eerrno == ENOENT || eerrno == ENOTDIR ? 0 : -1; +} +#endif /* defined(HAVE_GLOB) */ + +/** Return a new list containing the paths that match the pattern + * <b>pattern</b>. Return NULL on error. On POSIX systems, errno is set by the + * glob function or is set to EPERM if glob tried to access a file not allowed + * by the seccomp sandbox. + */ +struct smartlist_t * +tor_glob(const char *pattern) +{ + smartlist_t *result = NULL; + +#ifdef _WIN32 + // PathMatchSpec does not support forward slashes, change them to backslashes + char *pattern_normalized = tor_strdup(pattern); + tor_strreplacechar(pattern_normalized, '/', *PATH_SEPARATOR); + result = get_glob_paths(pattern_normalized, unglob_win32, true); + tor_free(pattern_normalized); +#elif HAVE_GLOB /* !(defined(_WIN32)) */ + glob_t matches; + int flags = GLOB_NOSORT; +#ifdef GLOB_ALTDIRFUNC + /* use functions that call sandbox_intern_string */ + flags |= GLOB_ALTDIRFUNC; + typedef void *(*gl_opendir)(const char * name); + typedef struct dirent *(*gl_readdir)(void *); + typedef void (*gl_closedir)(void *); + matches.gl_opendir = (gl_opendir) &prot_opendir; + matches.gl_readdir = (gl_readdir) &readdir; + matches.gl_closedir = (gl_closedir) &wrap_closedir; + matches.gl_stat = &prot_stat; + matches.gl_lstat = &prot_lstat; +#endif /* defined(GLOB_ALTDIRFUNC) */ + // use custom error handler to workaround BSD quirks and do not set GLOB_ERR + // because it would make glob fail on error even if the error handler ignores + // the error + int ret = glob(pattern, flags, glob_errfunc, &matches); + if (ret == GLOB_NOMATCH) { + return smartlist_new(); + } else if (ret != 0) { + return NULL; + } + + // #40141: workaround for bug in glibc < 2.19 where patterns ending in path + // separator match files and folders instead of folders only + size_t pattern_len = strlen(pattern); + bool dir_only = has_glob(pattern) && + pattern_len > 0 && pattern[pattern_len-1] == *PATH_SEPARATOR; + + result = smartlist_new(); + size_t i; + for (i = 0; i < matches.gl_pathc; i++) { + char *match = tor_strdup(matches.gl_pathv[i]); + size_t len = strlen(match); + if (len > 0 && match[len-1] == *PATH_SEPARATOR) { + match[len-1] = '\0'; + } + + if (!dir_only || (dir_only && is_dir(file_status(match)))) { + smartlist_add(result, match); + } else { + tor_free(match); + } + } + globfree(&matches); +#else + (void)pattern; + return result; +#endif /* !defined(HAVE_GLOB) */ + + return result; +} + +/** Returns true if <b>s</b> contains characters that can be globbed. + * Returns false otherwise. */ +bool +has_glob(const char *s) +{ + int i; + for (i = 0; s[i]; i++) { + if (is_glob_char(s, i)) { + return true; + } + } + return false; +} + +/** Expands globs in <b>pattern</b> for the path fragment between + * <b>prev_sep</b> and <b>next_sep</b> using tor_glob. Returns NULL on + * failure. Used by get_glob_opened_files. Implements unglob_fn, see its + * description for more details. */ +static struct smartlist_t * +unglob_opened_files(const char *pattern, int prev_sep, int next_sep) +{ + (void)prev_sep; + smartlist_t *result = smartlist_new(); + // if the following fragments have no globs, we're done + if (has_glob(&pattern[next_sep+1])) { + // if there is a glob after next_sep, we know next_sep is a separator and + // not the last char and glob_path will have the path without the separator + char *glob_path = tor_strndup(pattern, next_sep); + smartlist_t *child_paths = tor_glob(glob_path); + tor_free(glob_path); + if (!child_paths) { + smartlist_free(result); + result = NULL; + } else { + smartlist_add_all(result, child_paths); + smartlist_free(child_paths); + } + } + return result; +} + +/** Returns a list of files that are opened by the tor_glob function when + * called with <b>pattern</b>. Returns NULL on error. The purpose of this + * function is to create a list of files to be added to the sandbox white list + * before the sandbox is enabled. */ +struct smartlist_t * +get_glob_opened_files(const char *pattern) +{ + return get_glob_paths(pattern, unglob_opened_files, false); +} |