On 02/13/2013 09:20 AM, Jan Safranek wrote:
> On 02/11/2013 06:09 PM, Peter Schiffer wrote:
>> mkdir(2) function returns EROFS error even when the path already exists on
>> the
>> read only file system, so it is impossible to determine whether the path
>> already
>> exists on this kind of fs only be return code from the mkdir(2). To make
>> cg_mkdir_p() compatible with the ro fs, the function checks whether the path
>> exists with stat(2) before trying to create it.
>>
>> Signed-off-by: Peter Schiffer <[email protected]>
>> ---
>> 0 files changed
>>
>> diff --git a/src/api.c b/src/api.c
>> index 11cd1b4..4acdc30 100644
>> --- a/src/api.c
>> +++ b/src/api.c
>> @@ -1271,6 +1271,7 @@ int cg_mkdir_p(const char *path)
>> int i = 0;
>> char pos;
>> int ret = 0;
>> + struct stat st;
>>
>> real_path = strdup(path);
>> if (!real_path) {
>> @@ -1287,6 +1288,10 @@ int cg_mkdir_p(const char *path)
>> i++;
>> pos = real_path[i];
>> real_path[i] = '\0'; /* Temporarily overwrite "/" */
>> + if (stat(real_path, &st) == 0) { /* Continue if
>> dir exists */
>> + real_path[i] = pos;
>> + continue;
>> + }
>> ret = mkdir(real_path, S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH);
>> real_path[i] = pos;
>> if (ret) {
>
> This is classical TOCTTOU. While it does not have any security
> implications, it would be better to mkdir() and only if it fails, then
> check if the directory was already there.
>
> Jan
>
Thanks. What about this one?
peter
diff --git a/src/api.c b/src/api.c
index 11cd1b4..b5bbb74 100644
--- a/src/api.c
+++ b/src/api.c
@@ -1270,7 +1270,8 @@ int cg_mkdir_p(const char *path)
char *real_path = NULL;
int i = 0;
char pos;
- int ret = 0;
+ int ret = 0, stat_ret;
+ struct stat st;
real_path = strdup(path);
if (!real_path) {
@@ -1298,6 +1299,14 @@ int cg_mkdir_p(const char *path)
ret = ECGROUPNOTOWNER;
goto done;
default:
+ /* Check if path exists */
+ real_path[i] = '\0';
+ stat_ret = stat(real_path, &st);
+ real_path[i] = pos;
+ if (stat_ret == 0) {
+ ret = 0; /* Path exists */
+ break;
+ }
ret = ECGROUPNOTALLOWED;
goto done;
}
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