From 88404d41ea8dccd2488d66edc3fed64454ce8566 Mon Sep 17 00:00:00 2001 From: "Kartik K. Agaram" Date: Sun, 30 Jan 2022 12:08:40 -0800 Subject: copy realpath() from FreeBSD repo To sandbox apps robustly, we're going to need to always work with canonical absolute paths. --- src/Makefile | 3 +- src/realpath.c | 243 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 245 insertions(+), 1 deletion(-) create mode 100644 src/realpath.c diff --git a/src/Makefile b/src/Makefile index c1334ad..a9f39a2 100644 --- a/src/Makefile +++ b/src/Makefile @@ -26,7 +26,7 @@ LUA_A= liblua.a CORE_O= lapi.o lcode.o ldebug.o ldo.o ldump.o lfunc.o lgc.o llex.o lmem.o \ lobject.o lopcodes.o lparser.o lstate.o lstring.o ltable.o ltm.o \ lundump.o lvm.o lzio.o \ - lfs.o kilo.o tlv.o teliva.o + realpath.o lfs.o kilo.o tlv.o teliva.o LIB_O= lauxlib.o lbaselib.o ldblib.o liolib.o lmathlib.o loslib.o \ ltablib.o lstrlib.o loadlib.o linit.o @@ -189,6 +189,7 @@ lzio.o: lzio.c lua.h luaconf.h llimits.h lmem.h lstate.h lobject.h ltm.h \ lzio.h print.o: print.c ldebug.h lstate.h lua.h luaconf.h lobject.h llimits.h \ ltm.h lzio.h lmem.h lopcodes.h lundump.h +realpath.o: realpath.c lfs.o: lfs.c lfs.h lua.h lauxlib.h lualib.h kilo.o: kilo.c lua.h teliva.h teliva.o: teliva.c lua.h lauxlib.h lualib.h teliva.h tlv.h diff --git a/src/realpath.c b/src/realpath.c new file mode 100644 index 0000000..dc57bbb --- /dev/null +++ b/src/realpath.c @@ -0,0 +1,243 @@ +/* + * Copyright (c) 2003 Constantin S. Svintsoff + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The names of the authors may not be used to endorse or promote + * products derived from this software without specific prior written + * permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include + +#include +#include + +#include +#include +#include +#include + +/* + * Find the real name of path, by removing all ".", ".." and symlink + * components. Returns (resolved) on success, or (NULL) on failure, + * in which case the path which caused trouble is left in (resolved). + */ +char * +realpath(const char * __restrict path, char * __restrict resolved) +{ + struct stat sb; + char *p, *q, *s; + size_t left_len, resolved_len; + unsigned symlinks; + int m, slen; + char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX]; + + if (path == NULL) { + errno = EINVAL; + return (NULL); + } + if (path[0] == '\0') { + errno = ENOENT; + return (NULL); + } + if (resolved == NULL) { + resolved = malloc(PATH_MAX); + if (resolved == NULL) + return (NULL); + m = 1; + } else + m = 0; + symlinks = 0; + if (path[0] == '/') { + resolved[0] = '/'; + resolved[1] = '\0'; + if (path[1] == '\0') + return (resolved); + resolved_len = 1; + left_len = strlcpy(left, path + 1, sizeof(left)); + } else { + if (getcwd(resolved, PATH_MAX) == NULL) { + if (m) + free(resolved); + else { + resolved[0] = '.'; + resolved[1] = '\0'; + } + return (NULL); + } + resolved_len = strlen(resolved); + left_len = strlcpy(left, path, sizeof(left)); + } + if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) { + if (m) + free(resolved); + errno = ENAMETOOLONG; + return (NULL); + } + + /* + * Iterate over path components in `left'. + */ + while (left_len != 0) { + /* + * Extract the next path component and adjust `left' + * and its length. + */ + p = strchr(left, '/'); + s = p ? p : left + left_len; + if (s - left >= sizeof(next_token)) { + if (m) + free(resolved); + errno = ENAMETOOLONG; + return (NULL); + } + memcpy(next_token, left, s - left); + next_token[s - left] = '\0'; + left_len -= s - left; + if (p != NULL) + memmove(left, s + 1, left_len + 1); + if (resolved[resolved_len - 1] != '/') { + if (resolved_len + 1 >= PATH_MAX) { + if (m) + free(resolved); + errno = ENAMETOOLONG; + return (NULL); + } + resolved[resolved_len++] = '/'; + resolved[resolved_len] = '\0'; + } + if (next_token[0] == '\0') { + /* + * Handle consequential slashes. The path + * before slash shall point to a directory. + * + * Only the trailing slashes are not covered + * by other checks in the loop, but we verify + * the prefix for any (rare) "//" or "/\0" + * occurrence to not implement lookahead. + */ + if (lstat(resolved, &sb) != 0) { + if (m) + free(resolved); + return (NULL); + } + if (!S_ISDIR(sb.st_mode)) { + if (m) + free(resolved); + errno = ENOTDIR; + return (NULL); + } + continue; + } + else if (strcmp(next_token, ".") == 0) + continue; + else if (strcmp(next_token, "..") == 0) { + /* + * Strip the last path component except when we have + * single "/" + */ + if (resolved_len > 1) { + resolved[resolved_len - 1] = '\0'; + q = strrchr(resolved, '/') + 1; + *q = '\0'; + resolved_len = q - resolved; + } + continue; + } + + /* + * Append the next path component and lstat() it. + */ + resolved_len = strlcat(resolved, next_token, PATH_MAX); + if (resolved_len >= PATH_MAX) { + if (m) + free(resolved); + errno = ENAMETOOLONG; + return (NULL); + } + if (lstat(resolved, &sb) != 0) { + if (m) + free(resolved); + return (NULL); + } + if (S_ISLNK(sb.st_mode)) { + if (symlinks++ > MAXSYMLINKS) { + if (m) + free(resolved); + errno = ELOOP; + return (NULL); + } + slen = readlink(resolved, symlink, sizeof(symlink) - 1); + if (slen < 0) { + if (m) + free(resolved); + return (NULL); + } + symlink[slen] = '\0'; + if (symlink[0] == '/') { + resolved[1] = 0; + resolved_len = 1; + } else if (resolved_len > 1) { + /* Strip the last path component. */ + resolved[resolved_len - 1] = '\0'; + q = strrchr(resolved, '/') + 1; + *q = '\0'; + resolved_len = q - resolved; + } + + /* + * If there are any path components left, then + * append them to symlink. The result is placed + * in `left'. + */ + if (p != NULL) { + if (symlink[slen - 1] != '/') { + if (slen + 1 >= sizeof(symlink)) { + if (m) + free(resolved); + errno = ENAMETOOLONG; + return (NULL); + } + symlink[slen] = '/'; + symlink[slen + 1] = 0; + } + left_len = strlcat(symlink, left, + sizeof(symlink)); + if (left_len >= sizeof(left)) { + if (m) + free(resolved); + errno = ENAMETOOLONG; + return (NULL); + } + } + left_len = strlcpy(left, symlink, sizeof(left)); + } + } + + /* + * Remove trailing slash except when the resolved pathname + * is a single "/". + */ + if (resolved_len > 1 && resolved[resolved_len - 1] == '/') + resolved[resolved_len - 1] = '\0'; + return (resolved); +} -- cgit 1.4.1-2-gfad0