We can blindly send a negotiate signing context on every negotiate call,
as it doesn't affect the current behaviour; even though we set AES-GMAC
as the first signing algorithm (i.e. our preferred algorithm), it will
use AES-CMAC if:
a) the server doesn't respond to signing negotiations
b) the server responds that it only supports AES-GMAC
So this is a safe change.
Throw a warning if 'enable_negotiate_signing=0' was explicitly set, but
ignore it and set it back to true.
Signed-off-by: Enzo Matsumiya <ematsumiya@xxxxxxx>
---
fs/cifs/cifsfs.c | 8 ++++++--
fs/cifs/cifsglob.h | 3 ++-
fs/cifs/smb2pdu.c | 21 ++++++++++++---------
3 files changed, 20 insertions(+), 12 deletions(-)
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index e9fb338b8e7e..40dcb0b73bea 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -65,7 +65,7 @@ bool lookupCacheEnabled = true;
bool disable_legacy_dialects; /* false by default */
bool enable_gcm_256 = true;
bool require_gcm_256; /* false by default */
-bool enable_negotiate_signing; /* false by default */
+bool enable_negotiate_signing = true; /* deprecated -- always true now */
unsigned int global_secflags = CIFSSEC_DEF;
/* unsigned int ntlmv2_support = 0; */
unsigned int sign_CIFS_PDUs = 1;
@@ -133,8 +133,12 @@ MODULE_PARM_DESC(enable_gcm_256, "Enable requesting strongest (256 bit) GCM encr
module_param(require_gcm_256, bool, 0644);
MODULE_PARM_DESC(require_gcm_256, "Require strongest (256 bit) GCM encryption. Default: n/N/0");
+/* XXX: remove this at some point */
module_param(enable_negotiate_signing, bool, 0644);
-MODULE_PARM_DESC(enable_negotiate_signing, "Enable negotiating packet signing algorithm with server. Default: n/N/0");
+MODULE_PARM_DESC(enable_negotiate_signing,
+ "(deprecated) Enable negotiating packet signing algorithm with the server. "
+ "Default: always y/Y/1. Changing this setting no longer has any effect, cifs.ko "
+ "will always try to negotiate the signing algorithm on SMB 3.1.1 mounts.");
module_param(disable_legacy_dialects, bool, 0644);
MODULE_PARM_DESC(disable_legacy_dialects, "To improve security it may be "
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 0ce2ceaf039e..c1524e0ddad6 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -2015,7 +2015,8 @@ extern unsigned int global_secflags; /* if on, session setup sent
extern unsigned int sign_CIFS_PDUs; /* enable smb packet signing */
extern bool enable_gcm_256; /* allow optional negotiate of strongest signing (aes-gcm-256) */
extern bool require_gcm_256; /* require use of strongest signing (aes-gcm-256) */
-extern bool enable_negotiate_signing; /* request use of faster (GMAC) signing if available */
+/* XXX: remove enable_negotiate_signing at some point */
+extern bool enable_negotiate_signing; /* (deprecated) request to use AES-GMAC signing if supported */
extern bool linuxExtEnabled;/*enable Linux/Unix CIFS extensions*/
extern unsigned int CIFSMaxBufSize; /* max size not including hdr */
extern unsigned int cifs_min_rcv; /* min size of big ntwrk buf pool */
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 45215e4e6f37..d51dfe3bb163 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -614,14 +614,18 @@ assemble_neg_contexts(struct smb2_negotiate_req *req,
neg_context_count++;
}
- if (enable_negotiate_signing) {
- ctxt_len = build_signing_ctxt((struct smb2_signing_capabilities *)
- pneg_ctxt);
- *total_len += ctxt_len;
- pneg_ctxt += ctxt_len;
- neg_context_count++;
+ if (!enable_negotiate_signing) {
+ pr_warn("cifs.ko loaded with param 'enable_negotiate_signing=0', but this parameter "
+ "is deprecated. Trying to negotiate signing capabilities anyway...");
+ enable_negotiate_signing = true;
}
+ ctxt_len = build_signing_ctxt((struct smb2_signing_capabilities *)
+ pneg_ctxt);
+ *total_len += ctxt_len;
+ pneg_ctxt += ctxt_len;
+ neg_context_count++;
+
/* check for and add transport_capabilities and signing capabilities */
req->NegotiateContextCount = cpu_to_le16(neg_context_count);
}
@@ -818,8 +822,7 @@ static int smb311_decode_neg_context(struct smb2_negotiate_rsp *rsp,
}
/*
- * Throw a warning if user requested signing to be negotiated, but it
- * wasn't.
+ * Throw a warning if signing context was not negotiated.
*
* Some servers will not send a SMB2_SIGNING_CAPABILITIES context (*),
* so we use AES-CMAC (default in smb311 ops) as it is expected to be
@@ -827,7 +830,7 @@ static int smb311_decode_neg_context(struct smb2_negotiate_rsp *rsp,
*
* (*) see note "<125> Section 3.2.4.2.2.2" in MS-SMB2
*/
- if (!server->signing_negotiated && enable_negotiate_signing)
+ if (!server->signing_negotiated)
cifs_dbg(VFS, "signing capabilities were not negotiated, using "
"AES-CMAC for message signing\n");
--
2.35.3
