diff --git a/lib/libc/stdlib/realpath.c b/lib/libc/stdlib/realpath.c index 4c52b73319ab..18f29e95ee6b 100644 --- a/lib/libc/stdlib/realpath.c +++ b/lib/libc/stdlib/realpath.c @@ -1,229 +1,239 @@ /*- * SPDX-License-Identifier: BSD-3-Clause * * 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 #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). */ static char * __noinline realpath1(const char *path, char *resolved) { struct stat sb; char *p, *q; - size_t left_len, resolved_len, next_token_len; + size_t left_len, prev_len, resolved_len, next_token_len; unsigned symlinks; ssize_t slen; char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX]; 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) { 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) { 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, '/'); next_token_len = p != NULL ? (size_t)(p - left) : left_len; memcpy(next_token, left, next_token_len); next_token[next_token_len] = '\0'; if (p != NULL) { left_len -= next_token_len + 1; memmove(left, p + 1, left_len + 1); } else { left[0] = '\0'; left_len = 0; } + prev_len = resolved_len; if (resolved[resolved_len - 1] != '/') { if (resolved_len + 1 >= PATH_MAX) { errno = ENAMETOOLONG; return (NULL); } resolved[resolved_len++] = '/'; resolved[resolved_len] = '\0'; } if (next_token[0] == '\0') { /* Handle consequential slashes. */ 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) { errno = ENAMETOOLONG; return (NULL); } - if (lstat(resolved, &sb) != 0) + if (lstat(resolved, &sb) != 0) { + /* + * EACCES means the parent directory is not + * readable, while ENOTDIR means the parent + * directory is not a directory. Rewind the path + * to correctly indicate where the error lies. + */ + if (errno == EACCES || errno == ENOTDIR) + resolved[prev_len] = '\0'; return (NULL); + } if (S_ISLNK(sb.st_mode)) { if (symlinks++ > MAXSYMLINKS) { errno = ELOOP; return (NULL); } slen = readlink(resolved, symlink, sizeof(symlink)); if (slen < 0) return (NULL); if (slen == 0) { errno = ENOENT; return (NULL); } if ((size_t)slen >= sizeof(symlink)) { errno = ENAMETOOLONG; return (NULL); } symlink[slen] = '\0'; if (symlink[0] == '/') { resolved[1] = 0; resolved_len = 1; } else { /* Strip the last path component. */ 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 ((size_t)slen + 1 >= sizeof(symlink)) { errno = ENAMETOOLONG; return (NULL); } symlink[slen] = '/'; symlink[slen + 1] = 0; } left_len = strlcat(symlink, left, sizeof(symlink)); if (left_len >= sizeof(symlink)) { errno = ENAMETOOLONG; return (NULL); } } left_len = strlcpy(left, symlink, sizeof(left)); } else if (!S_ISDIR(sb.st_mode) && p != NULL) { errno = ENOTDIR; return (NULL); } } /* * 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); } char * __ssp_real(realpath)(const char * __restrict path, char * __restrict resolved) { char *m, *res; if (path == NULL) { errno = EINVAL; return (NULL); } if (path[0] == '\0') { errno = ENOENT; return (NULL); } if (resolved != NULL) { m = NULL; } else { m = resolved = malloc(PATH_MAX); if (resolved == NULL) return (NULL); } if (__sys___realpathat(AT_FDCWD, path, resolved, PATH_MAX, 0) == 0) { return (resolved); } res = realpath1(path, resolved); if (res == NULL) free(m); return (res); } diff --git a/lib/libc/tests/gen/realpath2_test.c b/lib/libc/tests/gen/realpath2_test.c index b8f951d9b10f..431df8721ae0 100644 --- a/lib/libc/tests/gen/realpath2_test.c +++ b/lib/libc/tests/gen/realpath2_test.c @@ -1,188 +1,181 @@ /* * Copyright (c) 2017 Jan Kokemüller * All rights reserved. * Copyright (c) 2025 Klara, Inc. * * 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. * * 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 #include #include ATF_TC(realpath_null); ATF_TC_HEAD(realpath_null, tc) { atf_tc_set_md_var(tc, "descr", "Test null input"); } ATF_TC_BODY(realpath_null, tc) { ATF_REQUIRE_ERRNO(EINVAL, realpath(NULL, NULL) == NULL); } ATF_TC(realpath_empty); ATF_TC_HEAD(realpath_empty, tc) { atf_tc_set_md_var(tc, "descr", "Test empty input"); } ATF_TC_BODY(realpath_empty, tc) { char resb[PATH_MAX] = ""; ATF_REQUIRE_EQ(0, mkdir("foo", 0755)); ATF_REQUIRE_EQ(0, chdir("foo")); ATF_REQUIRE_ERRNO(ENOENT, realpath("", resb) == NULL); ATF_REQUIRE_STREQ("", resb); } ATF_TC(realpath_buffer_overflow); ATF_TC_HEAD(realpath_buffer_overflow, tc) { atf_tc_set_md_var(tc, "descr", "Test for out of bounds read from 'left' array " "(compile realpath.c with '-fsanitize=address')"); } ATF_TC_BODY(realpath_buffer_overflow, tc) { char path[PATH_MAX] = ""; char resb[PATH_MAX] = ""; memset(path, 'a', sizeof(path) - 1); path[1] = '/'; ATF_REQUIRE(realpath(path, resb) == NULL); } ATF_TC(realpath_empty_symlink); ATF_TC_HEAD(realpath_empty_symlink, tc) { atf_tc_set_md_var(tc, "descr", "Test for correct behavior when encountering empty symlinks"); } ATF_TC_BODY(realpath_empty_symlink, tc) { char path[PATH_MAX] = ""; char slnk[PATH_MAX] = ""; char resb[PATH_MAX] = ""; int fd; (void)strlcat(slnk, "empty_symlink", sizeof(slnk)); ATF_REQUIRE(symlink("", slnk) == 0); fd = open("aaa", O_RDONLY | O_CREAT, 0600); ATF_REQUIRE(fd >= 0); ATF_REQUIRE(close(fd) == 0); (void)strlcat(path, "empty_symlink", sizeof(path)); (void)strlcat(path, "/aaa", sizeof(path)); ATF_REQUIRE_ERRNO(ENOENT, realpath(path, resb) == NULL); ATF_REQUIRE(unlink("aaa") == 0); ATF_REQUIRE(unlink(slnk) == 0); } ATF_TC(realpath_partial); ATF_TC_HEAD(realpath_partial, tc) { atf_tc_set_md_var(tc, "descr", "Test that failure leaves a partial result"); atf_tc_set_md_var(tc, "require.user", "unprivileged"); } ATF_TC_BODY(realpath_partial, tc) { char resb[PATH_MAX] = ""; size_t len; /* scenario 1: missing directory */ ATF_REQUIRE_EQ(0, mkdir("foo", 0755)); ATF_REQUIRE_ERRNO(ENOENT, realpath("foo/bar/baz", resb) == NULL); len = strnlen(resb, sizeof(resb)); ATF_REQUIRE(len > 8 && len < sizeof(resb)); ATF_REQUIRE_STREQ("/foo/bar", resb + len - 8); /* scenario 2: dead link 1 */ ATF_REQUIRE_EQ(0, symlink("nix", "foo/bar")); ATF_REQUIRE_ERRNO(ENOENT, realpath("foo/bar/baz", resb) == NULL); len = strnlen(resb, sizeof(resb)); ATF_REQUIRE(len > 8 && len < sizeof(resb)); ATF_REQUIRE_STREQ("/foo/nix", resb + len - 8); /* scenario 3: missing file */ ATF_REQUIRE_EQ(0, unlink("foo/bar")); ATF_REQUIRE_EQ(0, mkdir("foo/bar", 0755)); ATF_REQUIRE_ERRNO(ENOENT, realpath("foo/bar/baz", resb) == NULL); len = strnlen(resb, sizeof(resb)); ATF_REQUIRE(len > 12 && len < sizeof(resb)); ATF_REQUIRE_STREQ("/foo/bar/baz", resb + len - 12); /* scenario 4: dead link 2 */ ATF_REQUIRE_EQ(0, symlink("nix", "foo/bar/baz")); ATF_REQUIRE_ERRNO(ENOENT, realpath("foo/bar/baz", resb) == NULL); len = strnlen(resb, sizeof(resb)); ATF_REQUIRE(len > 12 && len < sizeof(resb)); ATF_REQUIRE_STREQ("/foo/bar/nix", resb + len - 12); /* scenario 5: unreadable directory */ ATF_REQUIRE_EQ(0, chmod("foo", 000)); ATF_REQUIRE_ERRNO(EACCES, realpath("foo/bar/baz", resb) == NULL); len = strnlen(resb, sizeof(resb)); - ATF_REQUIRE(len > 8 && len < sizeof(resb)); - /* - * This is arguably wrong. The problem is not with bar, but with - * foo. However, since foo exists and is a directory and the only - * reliable way to detect whether a directory is readable is to - * attempt to read it, we do not detect the problem until we try - * to access bar. - */ - ATF_REQUIRE_STREQ("/foo/bar", resb + len - 8); + ATF_REQUIRE(len > 4 && len < sizeof(resb)); + ATF_REQUIRE_STREQ("/foo", resb + len - 4); /* scenario 6: not a directory */ ATF_REQUIRE_EQ(0, close(creat("bar", 0644))); ATF_REQUIRE_ERRNO(ENOTDIR, realpath("bar/baz", resb) == NULL); len = strnlen(resb, sizeof(resb)); ATF_REQUIRE(len > 4 && len < sizeof(resb)); ATF_REQUIRE_STREQ("/bar", resb + len - 4); } ATF_TP_ADD_TCS(tp) { ATF_TP_ADD_TC(tp, realpath_null); ATF_TP_ADD_TC(tp, realpath_empty); ATF_TP_ADD_TC(tp, realpath_buffer_overflow); ATF_TP_ADD_TC(tp, realpath_empty_symlink); ATF_TP_ADD_TC(tp, realpath_partial); return atf_no_error(); }