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libselinux: correct error path to always try text

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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@intel.com>
This commit is contained in:
William Roberts 2016-09-16 12:37:16 -07:00 committed by Stephen Smalley
parent 72b43e523d
commit ba9bb2ebcb
1 changed files with 32 additions and 15 deletions
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35
libselinux/src/label_file.c
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@ -414,7 +414,7 @@ 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;
@ -460,9 +460,15 @@ 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);
}
@ -482,24 +488,35 @@ 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);
/*
* 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;
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;
if (!rc)
return 0;
}
return -1;
}
static void closef(struct selabel_handle *rec);