On 09/16/2016 02:32 PM, william.c.roberts@xxxxxxxxx wrote:
> From: William Roberts <william.c.roberts@xxxxxxxxx>
>
> patch 5e15a52aaa cleans up the process_file() routine,
> but introduced a bug. If the binary file cannot be
> opened, always attempt to fall back to the textual file,
> this was not occurring.
>
> The logic should be:
> 1. Open the newest file between base path + suffix and
> base_path + suffix + ".bin"
> 2. If anything fails, attempt to load the oldest file.
>
> The result, with a concrete example, would be:
> If file_contexts is the newest file, and it cannot be
> processed, the code will fall back to file_contexts.bin
> and vice versa.
>
> Signed-off-by: William Roberts <william.c.roberts@xxxxxxxxx>
> ---
> libselinux/src/label_file.c | 48 +++++++++++++++++++++++++++++++--------------
> 1 file changed, 33 insertions(+), 15 deletions(-)
>
> diff --git a/libselinux/src/label_file.c b/libselinux/src/label_file.c
> index 9faecdb..4f3700c 100644
> --- a/libselinux/src/label_file.c
> +++ b/libselinux/src/label_file.c
> @@ -447,7 +447,7 @@ static bool fcontext_is_binary(FILE *fp)
> #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)
> + char *save_path, size_t len, struct stat *sb, bool open_oldest)
> {
> unsigned int i;
> int rc;
> @@ -493,9 +493,17 @@ static FILE *open_file(const char *path, const char *suffix,
> * 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.
> + * even if the time stamp is the same. Invert this logic
> + * on open_oldest set to true. The idea is that if the
> + * newest file failed to process, we can attempt to
> + * process the oldest. The logic here is subtle and depends
> + * on the array ordering in fdetails for the case when time
> + * stamps are the same.
> */
> - if (fdetails[i].sb.st_mtime >= found->sb.st_mtime) {
> + if ((!open_oldest
> + && fdetails[i].sb.st_mtime >= found->sb.st_mtime)
> + || (open_oldest
> + && fdetails[i].sb.st_mtime < found->sb.st_mtime)) {
This can be simplified using ^ (xor).
> found = &fdetails[i];
> strcpy(save_path, path);
> }
> @@ -515,24 +523,34 @@ static int process_file(const char *path, const char *suffix,
> const char *prefix, struct selabel_digest *digest)
> {
> int rc;
> + unsigned int i;
> struct stat sb;
> FILE *fp = NULL;
> char found_path[PATH_MAX];
>
> - fp = open_file(path, suffix, found_path, sizeof(found_path), &sb);
> - if (fp == NULL)
> - return -1;
> + /*
> + * first path open the newest modified file, if it fails, the second
pass, opens
> + * pass opens the oldest file. If both passes fail, its a fatal error.
it is
> + */
> + for (i = 0; i < 2; i++) {
> + fp = open_file(path, suffix, found_path, sizeof(found_path),
> + &sb, i > 0);
> + if (fp == NULL)
> + return -1;
>
> - 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 = fcontext_is_binary(fp) ?
> + load_mmap(fp, sb.st_size, rec, found_path) :
> + process_text_file(fp, prefix, rec, found_path);
> + if (!rc)
> + rc = digest_add_specfile(digest, fp, NULL, sb.st_size,
> + found_path);
>
> - rc = digest_add_specfile(digest, fp, NULL, sb.st_size, found_path);
> -out:
> - fclose(fp);
> - return rc;
> + fclose(fp);
> +
> + if (!rc)
> + return 0;
> + }
> + return -1;
> }
>
> static void closef(struct selabel_handle *rec);
>
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