scsi: target: compare full CHAP_A Algorithm strings

scsi: target: compare full CHAP_A Algorithm strings

[ Upstream commit 9cef2a7955f2754257a7cddedec16edae7b587d0 ]

RFC 2307 states:

  For CHAP [RFC1994], in the first step, the initiator MUST send:

      CHAP_A=<A1,A2...>

   Where A1,A2... are proposed algorithms, in order of preference.
...
   For the Algorithm, as stated in [RFC1994], one value is required to
   be implemented:

       5     (CHAP with MD5)

LIO currently checks for this value by only comparing a single byte in
the tokenized Algorithm string, which means that any value starting with
a '5' (e.g. "55") is interpreted as "CHAP with MD5". Fix this by
comparing the entire tokenized string.

Reviewed-by: Lee Duncan <lduncan@suse.com>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: David Disseldorp <ddiss@suse.de>
Link: https://lore.kernel.org/r/20190912095547.22427-2-ddiss@suse.de
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>