Bugs item #1790403, was opened at 2007-09-07 13:24
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Category: TFTP
Group: wrong behaviour
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: darpin (darpin1963)
Assigned to: Daniel Stenberg (bagder)
Summary: Permission Denied TFTP upload reports success

Initial Comment:
The Problem:
Performing a TFTP upload to a file without sufficient write permissions on the destination file results in an unreported failure.

Witnessed on:
Fedora Core 6
[root_at_dpiner01 ~]# uname -a
Linux dpiner01 2.6.22.2-42.fc6 #1 SMP Wed Aug 15 12:34:26 EDT 2007 i686 i686 i386 GNU/Linux

[root_at_dpiner01 ~]# curl -V
curl 7.15.5 (i686-redhat-linux-gnu) libcurl/7.15.5 OpenSSL/0.9.8b zlib/1.2.3 libidn/0.6.5
Protocols: tftp ftp telnet dict ldap http file https ftps
Features: GSS-Negotiate IDN IPv6 Largefile NTLM SSL libz

I also tried against curl-7.16.4.tar.gz configured with:
./configure --without-ssl --disable-shared --enable-debug

Programmatic usage (i.e., libcurl) compiled/linked with:
[root_at_dpiner01 ~]# g++ -v
Using built-in specs.
Target: i386-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-libgcj-multifile --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --enable-plugin --with-java-home=/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre --with-cpu=generic --host=i386-redhat-linux
Thread model: posix
gcc version 4.1.2 20070626 (Red Hat 4.1.2-13)

Recreating the problem on the command-line:
Create a file in the TFTP's directory (e.g., /tftpboot/junk.dat.)
   cd /tftpboot
   touch junk.dat
   ll junk.dat
[root_at_dpiner01 ~]# ll junk.dat
-rw-r--r-- 1 root root 0 Sep 7 10:43 junk.dat

Create and populate a file named /tmp/junk.dat.
   cat -> /tmp/junk.dat
   This is a junk file.
   ^D
   ll /tmp/junk.dat
[root_at_dpiner01 ~]# ll /tmp/junk.dat
-rw-r--r-- 1 root root 21 Sep 7 10:47 /tmp/junk.dat

In the /tmp directory, issue the following command:
   curl --verbose --upload-file junk.dat tftp://10.191.2.108/junk.dat

[root@dpiner01 tmp]# curl --verbose --upload-file junk.dat tftp://10.191.2.108/junk.dat
* About to connect() to 10.191.2.108 port 69
* Trying 10.191.2.108... connected
* Connected to 10.191.2.108 (10.191.2.108) port 69
* set timeouts for state 0; Total 30, retry 5 maxtry 6
* Permission denied
  % Total % Received % Xferd Average Speed Time Time Time Current
                                 Dload Upload Total Spent Left Speed
  0 21 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0* Closing connection #0

Examine the tftpboot directory:
   ll junk.dat
[root_at_dpiner01 tftpboot]# ll junk.dat
-rw-r--r-- 1 root root 0 Sep 7 10:43 junk.dat

(note the file size remains zero.)

Make it work:
   chmod 777 /tftpboot/junk.dat
[root_at_dpiner01 tftpboot]# ll junk.dat
-rwxrwxrwx 1 root root 0 Sep 7 10:43 junk.dat

Issue same curl command:
[root@dpiner01 tmp]# curl --verbose --upload-file junk.dat tftp://10.191.2.108/junk.dat
* About to connect() to 10.191.2.108 port 69
* Trying 10.191.2.108... connected
* Connected to 10.191.2.108 (10.191.2.108) port 69
* set timeouts for state 0; Total 30, retry 5 maxtry 6
  % Total % Received % Xferd Average Speed Time Time Time Current
                                 Dload Upload Total Spent Left Speed
  0 21 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0* Connected for transmit
* set timeouts for state 2; Total 3600, retry 15 maxtry 24
  0 21 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0* Closing connection #0

Examine the tftpboot directory:
[root_at_dpiner01 tftpboot]# ll junk.dat
-rwxrwxrwx 1 root root 21 Sep 7 10:54 junk.dat

(note the correct file size indicate the upload completed successfully.)

What happens in failure scenario:
   rm /tftpboot/junk.dat
   ll /tftpboot/junk.dat
[root_at_dpiner01 tftpboot]# ll /tftpboot/junk.dat
ls: /tftpboot/junk.dat: No such file or directory

Issue the same curl command:
   curl --verbose --upload-file junk.dat tftp://10.191.2.108/junk.dat

[root@dpiner01 tmp]# curl --verbose --upload-file junk.dat tftp://10.191.2.108/junk.dat
* About to connect() to 10.191.2.108 port 69
* Trying 10.191.2.108... connected
* Connected to 10.191.2.108 (10.191.2.108) port 69
* set timeouts for state 0; Total 30, retry 5 maxtry 6
* File not found
  % Total % Received % Xferd Average Speed Time Time Time Current
                                 Dload Upload Total Spent Left Speed
  0 21 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0* Closing connection #0
* TFTP: File Not Found

curl: (68) TFTP: File Not Found

Programmatically,the following snippet:

            string srcFile = "junk.dat";
            string url = "tftp://10.191.2.108/junk.dat";
            char errorBuffer[ 1024 ] = { 0, };

            CURL* handle = curl_easy_init();
            
            struct stat statusBuffer = { 0, };
            off_t fileSize = 0;
            stat( srcFile.c_str(), &statusBuffer );
            fileSize = statusBuffer.st_size;
            
            curl_easy_setopt( handle, CURLOPT_VERBOSE, true );
            curl_easy_setopt( handle, CURLOPT_URL, url.c_str() );
            curl_easy_setopt( handle, CURLOPT_READDATA, file );
            curl_easy_setopt( handle, CURLOPT_INFILESIZE, fileSize );
            curl_easy_setopt( handle, CURLOPT_UPLOAD, true );
            curl_easy_setopt( handle, CURLOPT_FAILONERROR, !0 );
            curl_easy_setopt( handle, CURLOPT_ERRORBUFFER, errorBuffer );
            curl_easy_setopt( handle, CURLOPT_TRANSFERTEXT, 0 );

            CURLcode result = curl_easy_perform( handle );
            if ( CURLE_OK == result )
            {
               printf( "OK\n" );
            }
            else
            {
               printf( "Bad - error: '%s'\n", outErrorBuffer );
            }
            curl_easy_cleanup( handle );

 In the permission denied scenario, curl_easy_perform reports CURLE_OK (i.e., OK is printf'd.)

Seems like CURLE_TFTP_PERM would be an appropriate return value.
curl.h: CURLE_TFTP_PERM, /* 69 - permission problem on server */

But then looking at the tftp utility's output in the failed scenario shows:

[root_at_dpiner01 tmp]# tftp -v 10.191.2.108
Connected to 10.191.2.108 (10.191.2.108), port 69
tftp> trace
Packet tracing on.
tftp> put junk.dat
putting junk.dat to 10.191.2.108:junk.dat [netascii]
sent WRQ <file=junk.dat, mode=netascii>
received ERROR <code=0, msg=Permission denied>
Error code 0: Permission denied

That is, the Permission denied error code = 0. Yikes! Which is troubling because the error checking logic in tftp.c assumes zero is the non-error case.

FWIW, the tftp software's version is:
[root_at_dpiner01 tmp]# rpm -qa | grep tftp
tftp-server-0.42-3.1
tftp-0.42-3.1

Would someone comment on this behavior? Is it a problem with cUrl (which in itself is wicked cool by the way?) Or, perhaps a problem with the tftp client or server?

Thank you.

++darrell

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Received on 2007-09-07