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d="scan'208";a="19028410" Received: from fmsmga002-icc.fm.intel.com ([198.175.99.35]) by emsm-gh1-uea11.nsa.gov with ESMTP; 07 Sep 2016 00:07:04 +0000 Received: from fmsmga003-icc.fm.intel.com ([198.175.99.8]) by fmsmga002-icc.fm.intel.com with ESMTP; 06 Sep 2016 17:07:03 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.30,294,1470726000"; d="scan'208";a="757815412" Received: from ggans-mobl4.amr.corp.intel.com (HELO wcrobert-MOBL1.amr.corp.intel.com) ([10.254.109.43]) by FMSMGA003.fm.intel.com with ESMTP; 06 Sep 2016 17:07:03 -0700 From: william.c.roberts@intel.com To: selinux@tycho.nsa.gov, seandroid-list@tycho.nsa.gov, sds@tycho.nsa.gov, jwcart2@tycho.nsa.gov Subject: [PATCH v2] libselinux: clean up process file Date: Tue, 6 Sep 2016 17:07:01 -0700 Message-Id: <1473206821-30222-1-git-send-email-william.c.roberts@intel.com> X-Mailer: git-send-email 1.9.1 X-BeenThere: selinux@tycho.nsa.gov X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Security-Enhanced Linux \(SELinux\) mailing list" List-Post: List-Help: MIME-Version: 1.0 Errors-To: selinux-bounces@tycho.nsa.gov Sender: "Selinux" X-Virus-Scanned: ClamAV using ClamSMTP From: William Roberts The current process_file() code will open the file twice on the case of a binary file, correct this. The general flow through process_file() was a bit difficult to read, streamline the routine to be more readable. Detailed statistics of before and after: Source lines of code reported by cloc on modified files: before: 735 after: 740 Object size difference: before: 195530 bytes after: 195529 bytes Signed-off-by: William Roberts --- libselinux/src/label_file.c | 263 ++++++++++++++++++++++++-------------------- 1 file changed, 145 insertions(+), 118 deletions(-) diff --git a/libselinux/src/label_file.c b/libselinux/src/label_file.c index c89bb35..6839a77 100644 --- a/libselinux/src/label_file.c +++ b/libselinux/src/label_file.c @@ -97,62 +97,43 @@ static int nodups_specs(struct saved_data *data, const char *path) return rc; } -static int load_mmap(struct selabel_handle *rec, const char *path, - struct stat *sb, bool isbinary, - struct selabel_digest *digest) +static int process_text_file(FILE *fp, const char *prefix, struct selabel_handle *rec, const char *path) +{ + /* + * Then do detailed validation of the input and fill the spec array + */ + int rc; + size_t line_len; + unsigned lineno = 0; + char *line_buf = NULL; + + while (getline(&line_buf, &line_len, fp) > 0) { + rc = process_line(rec, path, prefix, line_buf, ++lineno); + if (rc) + goto out; + } + rc = 0; +out: + free(line_buf); + return rc; +} + +static int load_mmap(FILE *fp, size_t len, struct selabel_handle *rec, const char *path) { struct saved_data *data = (struct saved_data *)rec->data; - char mmap_path[PATH_MAX + 1]; - int mmapfd; int rc; - struct stat mmap_stat; char *addr, *str_buf; - size_t len; int *stem_map; struct mmap_area *mmap_area; uint32_t i, magic, version; uint32_t entry_len, stem_map_len, regex_array_len; - if (isbinary) { - len = strlen(path); - if (len >= sizeof(mmap_path)) - return -1; - strcpy(mmap_path, path); - } else { - rc = snprintf(mmap_path, sizeof(mmap_path), "%s.bin", path); - if (rc >= (int)sizeof(mmap_path)) - return -1; - } - - mmapfd = open(mmap_path, O_RDONLY | O_CLOEXEC); - if (mmapfd < 0) - return -1; - - rc = fstat(mmapfd, &mmap_stat); - if (rc < 0) { - close(mmapfd); - return -1; - } - - /* if mmap is old, ignore it */ - if (mmap_stat.st_mtime < sb->st_mtime) { - close(mmapfd); - return -1; - } - - /* ok, read it in... */ - len = mmap_stat.st_size; - len += (sysconf(_SC_PAGE_SIZE) - 1); - len &= ~(sysconf(_SC_PAGE_SIZE) - 1); - mmap_area = malloc(sizeof(*mmap_area)); if (!mmap_area) { - close(mmapfd); return -1; } - addr = mmap(NULL, len, PROT_READ, MAP_PRIVATE, mmapfd, 0); - close(mmapfd); + addr = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fileno(fp), 0); if (addr == MAP_FAILED) { free(mmap_area); perror("mmap"); @@ -306,7 +287,7 @@ static int load_mmap(struct selabel_handle *rec, const char *path, if (strcmp(spec->lr.ctx_raw, "<>") && rec->validating) { if (selabel_validate(rec, &spec->lr) < 0) { selinux_log(SELINUX_ERROR, - "%s: context %s is invalid\n", mmap_path, spec->lr.ctx_raw); + "%s: context %s is invalid\n", path, spec->lr.ctx_raw); goto err; } } @@ -408,105 +389,151 @@ static int load_mmap(struct selabel_handle *rec, const char *path, data->nspec++; } - rc = digest_add_specfile(digest, NULL, addr, mmap_stat.st_size, - mmap_path); - if (rc) - goto err; - err: free(stem_map); return rc; } -static int process_file(const char *path, const char *suffix, - struct selabel_handle *rec, - const char *prefix, struct selabel_digest *digest) -{ - FILE *fp; +struct file_details { + const char *suffix; struct stat sb; - unsigned int lineno; - size_t line_len = 0; - char *line_buf = NULL; - int rc; - char stack_path[PATH_MAX + 1]; - bool isbinary = false; +}; + +static char *rolling_append(char *current, const char *suffix, size_t max) +{ + size_t size; + size_t suffix_size; + size_t current_size; + + if (!suffix) + return current; + + /* + * Overflow check that the following + * arithmatec will not overflow or + */ + current_size = strlen(current); + suffix_size = strlen(suffix); + + size = current_size + suffix_size; + if (size < current_size || size < suffix_size) + return NULL; + + /* ensure space for the '.' and the '\0' characters. */ + if (size >= (SIZE_MAX - 2)) + return NULL; + + size += 2; + + if (size > max) + return NULL; + + /* Append any given suffix */ + char *to = stpcpy(¤t[current_size], "."); + strcat(to, suffix); + + return current; +} + +static bool fcontext_is_binary(FILE *fp) +{ uint32_t magic; - /* append the path suffix if we have one */ - if (suffix) { - rc = snprintf(stack_path, sizeof(stack_path), - "%s.%s", path, suffix); - if (rc >= (int)sizeof(stack_path)) { - errno = ENAMETOOLONG; - return -1; - } - path = stack_path; + size_t len = fread(&magic, sizeof(magic), 1, fp); + rewind(fp); + + return (len && (magic == SELINUX_MAGIC_COMPILED_FCONTEXT)); +} + +#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) + +static FILE *open_file(const char *path, const char *suffix, + char *save_path, size_t len, struct stat *sb) +{ + unsigned i; + int rc; + char stack_path[len]; + struct file_details *found = NULL; + + /* + * Rolling append of suffix. Try to open with path.suffix then the + * next as path.suffix.suffix and so forth. + */ + struct file_details fdetails[2] = { + { .suffix = suffix }, + { .suffix = "bin" } + }; + + rc = snprintf(stack_path, sizeof(stack_path), "%s", path); + if (rc >= (int) sizeof(stack_path)) { + errno = ENAMETOOLONG; + return NULL; } - /* Open the specification file. */ - fp = fopen(path, "r"); - if (fp) { - __fsetlocking(fp, FSETLOCKING_BYCALLER); + for (i = 0; i < ARRAY_SIZE(fdetails); i++) { - if (fstat(fileno(fp), &sb) < 0) - return -1; - if (!S_ISREG(sb.st_mode)) { - errno = EINVAL; - return -1; - } + /* This handles the case if suffix is null */ + path = rolling_append(stack_path, fdetails[i].suffix, + sizeof(stack_path)); + if (!path) + return NULL; - magic = 0; - if (fread(&magic, sizeof magic, 1, fp) != 1) { - if (ferror(fp)) { - errno = EINVAL; - fclose(fp); - return -1; - } - clearerr(fp); - } + rc = stat(path, &fdetails[i].sb); + if (rc) + continue; - if (magic == SELINUX_MAGIC_COMPILED_FCONTEXT) { - /* file_contexts.bin format */ - fclose(fp); - fp = NULL; - isbinary = true; - } else { - rewind(fp); + /* first file thing found, just take it */ + if (!found) { + strcpy(save_path, path); + found = &fdetails[i]; + continue; } - } else { + /* - * Text file does not exist, so clear the timestamp - * so that we will always pass the timestamp comparison - * with the bin file in load_mmap(). + * Keep picking the newest file found. Where "newest" + * includes equality. This provides a precedence on + * secondary suffixes even when the timestamp is the + * same. Ie choose file_contexts.bin over file_contexts + * even if the time stamp is the same. */ - sb.st_mtime = 0; + if (fdetails[i].sb.st_mtime >= found->sb.st_mtime) { + found = &fdetails[i]; + strcpy(save_path, path); + } } - rc = load_mmap(rec, path, &sb, isbinary, digest); - if (rc == 0) - goto out; + if (!found) { + errno = ENOENT; + return NULL; + } - if (!fp) - return -1; /* no text or bin file */ + memcpy(sb, &found->sb, sizeof(*sb)); + return fopen(save_path, "r"); +} - /* - * Then do detailed validation of the input and fill the spec array - */ - lineno = 0; - rc = 0; - while (getline(&line_buf, &line_len, fp) > 0) { - rc = process_line(rec, path, prefix, line_buf, ++lineno); - if (rc) - goto out; - } +static int process_file(const char *path, const char *suffix, + struct selabel_handle *rec, + const char *prefix, struct selabel_digest *digest) +{ + int rc; + struct stat sb; + FILE *fp = NULL; + char found_path[PATH_MAX + 1]; + + fp = open_file(path, suffix, found_path, sizeof(found_path), &sb); + if (fp == NULL) + return -1; - rc = digest_add_specfile(digest, fp, NULL, sb.st_size, path); + rc = fcontext_is_binary(fp) ? + load_mmap(fp, sb.st_size, rec, found_path) : + process_text_file(fp, prefix, rec, found_path); + if (rc < 0) + goto out; + rc = digest_add_specfile(digest, fp, NULL, sb.st_size, found_path); out: - free(line_buf); - if (fp) - fclose(fp); + fclose(fp); return rc; }