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upstream: add a local implementation of BSD realpath() for
sftp-server use ahead of OpenBSD's realpath changing to match POSIX; ok deraadt@ (thanks for snaps testing) OpenBSD-Commit-ID: 4f8cbf7ed8679f6237264301d104ecec64885d55
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,224 @@ | ||
| /* $OpenBSD: sftp-realpath.c,v 1.1 2019/07/05 04:55:40 djm Exp $ */ | ||
| /* | ||
| * Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru> | ||
| * | ||
| * 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 <sys/types.h> | ||
| #include <sys/param.h> | ||
| #include <sys/stat.h> | ||
|
|
||
| #include <errno.h> | ||
| #include <stdlib.h> | ||
| #include <stddef.h> | ||
| #include <string.h> | ||
| #include <unistd.h> | ||
| #include <limits.h> | ||
|
|
||
| #ifndef SYMLOOP_MAX | ||
| # define SYMLOOP_MAX 32 | ||
| #endif | ||
|
|
||
| /* XXX rewrite sftp-server to use POSIX realpath and remove this hack */ | ||
|
|
||
| char *sftp_realpath(const char *path, char *resolved); | ||
|
|
||
| /* | ||
| * char *realpath(const char *path, char resolved[PATH_MAX]); | ||
| * | ||
| * 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 * | ||
| sftp_realpath(const char *path, char *resolved) | ||
| { | ||
| struct stat sb; | ||
| char *p, *q, *s; | ||
| size_t left_len, resolved_len; | ||
| unsigned symlinks; | ||
| int serrno, slen, mem_allocated; | ||
| char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX]; | ||
|
|
||
| if (path[0] == '\0') { | ||
| errno = ENOENT; | ||
| return (NULL); | ||
| } | ||
|
|
||
| serrno = errno; | ||
|
|
||
| if (resolved == NULL) { | ||
| resolved = malloc(PATH_MAX); | ||
| if (resolved == NULL) | ||
| return (NULL); | ||
| mem_allocated = 1; | ||
| } else | ||
| mem_allocated = 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 (mem_allocated) | ||
| free(resolved); | ||
| else | ||
| strlcpy(resolved, ".", PATH_MAX); | ||
| return (NULL); | ||
| } | ||
| resolved_len = strlen(resolved); | ||
| left_len = strlcpy(left, path, sizeof(left)); | ||
| } | ||
| if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) { | ||
| errno = ENAMETOOLONG; | ||
| goto err; | ||
| } | ||
|
|
||
| /* | ||
| * 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 >= (ptrdiff_t)sizeof(next_token)) { | ||
| errno = ENAMETOOLONG; | ||
| goto err; | ||
| } | ||
| 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) { | ||
| errno = ENAMETOOLONG; | ||
| goto err; | ||
| } | ||
| resolved[resolved_len++] = '/'; | ||
| resolved[resolved_len] = '\0'; | ||
| } | ||
| if (next_token[0] == '\0') | ||
| 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. If | ||
| * lstat() fails we still can return successfully if | ||
| * there are no more path components left. | ||
| */ | ||
| resolved_len = strlcat(resolved, next_token, PATH_MAX); | ||
| if (resolved_len >= PATH_MAX) { | ||
| errno = ENAMETOOLONG; | ||
| goto err; | ||
| } | ||
| if (lstat(resolved, &sb) != 0) { | ||
| if (errno == ENOENT && p == NULL) { | ||
| errno = serrno; | ||
| return (resolved); | ||
| } | ||
| goto err; | ||
| } | ||
| if (S_ISLNK(sb.st_mode)) { | ||
| if (symlinks++ > SYMLOOP_MAX) { | ||
| errno = ELOOP; | ||
| goto err; | ||
| } | ||
| slen = readlink(resolved, symlink, sizeof(symlink) - 1); | ||
| if (slen < 0) | ||
| goto err; | ||
| 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 >= | ||
| (ptrdiff_t)sizeof(symlink)) { | ||
| errno = ENAMETOOLONG; | ||
| goto err; | ||
| } | ||
| symlink[slen] = '/'; | ||
| symlink[slen + 1] = 0; | ||
| } | ||
| left_len = strlcat(symlink, left, sizeof(symlink)); | ||
| if (left_len >= sizeof(symlink)) { | ||
| errno = ENAMETOOLONG; | ||
| goto err; | ||
| } | ||
| } | ||
| 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); | ||
|
|
||
| err: | ||
| if (mem_allocated) | ||
| free(resolved); | ||
| return (NULL); | ||
| } |
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