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smb3: allow skipping signature verification for perf sensitive configurations

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Add new mount option "signloosely" which enables signing but skips the
sometimes expensive signing checks in the responses (signatures are
calculated and sent correctly in the SMB2/SMB3 requests even with this
mount option but skipped in the responses).  Although weaker for security
(and also data integrity in case a packet were corrupted), this can provide
enough of a performance benefit (calculating the signature to verify a
packet can be expensive especially for large packets) to be useful in
some cases.

Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
This commit is contained in:
Steve French 2019-09-03 21:18:49 -05:00
parent f90f979726
commit 4f5c10f1ad
3 changed files with 13 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
fs/cifs/cifsglob.h
View File

@ -542,6 +542,7 @@ struct smb_vol {
umode_t dir_mode;
enum securityEnum sectype; /* sectype requested via mnt opts */
bool sign; /* was signing requested via mnt opts? */
bool ignore_signature:1;
bool retry:1;
bool intr:1;
bool setuids:1;
@ -681,6 +682,7 @@ struct TCP_Server_Info {
char server_GUID[16];
__u16 sec_mode;
bool sign; /* is signing enabled on this connection? */
bool ignore_signature:1; /* skip validation of signatures in SMB2/3 rsp */
bool session_estab; /* mark when very first sess is established */
int echo_credits; /* echo reserved slots */
int oplock_credits; /* oplock break reserved slots */

13
fs/cifs/connect.c
View File

@ -91,7 +91,7 @@ enum {
Opt_serverino, Opt_noserverino,
Opt_rwpidforward, Opt_cifsacl, Opt_nocifsacl,
Opt_acl, Opt_noacl, Opt_locallease,
Opt_sign, Opt_seal, Opt_noac,
Opt_sign, Opt_ignore_signature, Opt_seal, Opt_noac,
Opt_fsc, Opt_mfsymlinks,
Opt_multiuser, Opt_sloppy, Opt_nosharesock,
Opt_persistent, Opt_nopersistent,
@ -183,6 +183,7 @@ static const match_table_t cifs_mount_option_tokens = {
{ Opt_noacl, "noacl" },
{ Opt_locallease, "locallease" },
{ Opt_sign, "sign" },
{ Opt_ignore_signature, "signloosely" },
{ Opt_seal, "seal" },
{ Opt_noac, "noac" },
{ Opt_fsc, "fsc" },
@ -1877,6 +1878,10 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
case Opt_sign:
vol->sign = true;
break;
case Opt_ignore_signature:
vol->sign = true;
vol->ignore_signature = true;
break;
case Opt_seal:
/* we do not do the following in secFlags because seal
* is a per tree connection (mount) not a per socket
@ -2608,6 +2613,9 @@ static int match_server(struct TCP_Server_Info *server, struct smb_vol *vol)
if (server->rdma != vol->rdma)
return 0;
if (server->ignore_signature != vol->ignore_signature)
return 0;
return 1;
}
@ -2785,7 +2793,7 @@ cifs_get_tcp_session(struct smb_vol *volume_info)
tcp_ses->tcpStatus = CifsNeedNegotiate;
tcp_ses->nr_targets = 1;
tcp_ses->ignore_signature = volume_info->ignore_signature;
/* thread spawned, put it on the list */
spin_lock(&cifs_tcp_ses_lock);
list_add(&tcp_ses->tcp_ses_list, &cifs_tcp_ses_list);
@ -3235,7 +3243,6 @@ cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb_vol *volume_info)
ses->sectype = volume_info->sectype;
ses->sign = volume_info->sign;
mutex_lock(&ses->session_mutex);
rc = cifs_negotiate_protocol(xid, ses);
if (!rc)

1
fs/cifs/smb2transport.c
View File

@ -522,6 +522,7 @@ smb2_verify_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
if ((shdr->Command == SMB2_NEGOTIATE) ||
(shdr->Command == SMB2_SESSION_SETUP) ||
(shdr->Command == SMB2_OPLOCK_BREAK) ||
server->ignore_signature ||
(!server->session_estab))
return 0;