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 | 47 ++++++++++++++++++++++++++++++---------------
1 file changed, 32 insertions(+), 15 deletions(-)
diff --git a/libselinux/src/label_file.c b/libselinux/src/label_file.c
index 9faecdb..ff6bc94 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 +493,15 @@ 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)) {
found = &fdetails[i];
strcpy(save_path, path);
}
@@ -515,24 +521,35 @@ 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;
+ /*
+ * On the first pass open the newest modified file. If it fails to
+ * process, then the second pass shall open the oldest file. If both
+ * passes fail, then it's a fatal error.
+ */
+ 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);
--
1.9.1
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