From: Olga Kornievskaia <[email protected]>
Ever since commit 2c94b8eca1a2 ("SUNRPC: Use au_rslack when computing
reply buffer size"). It changed how "req->rq_rcvsize" is calculated. It
used to use au_cslack value which was nice and large and changed it to
au_rslack value which turns out to be too small.
Since 5.1, v3 mount with sec=krb5p fails against an Ontap server
because client's receive buffer it too small.
For gss krb5p, we need to account for the mic token in the verifier,
and the wrap token in the wrap token.
RFC 4121 defines:
mic token
Octet no Name Description
--------------------------------------------------------------
0..1 TOK_ID Identification field. Tokens emitted by
GSS_GetMIC() contain the hex value 04 04
expressed in big-endian order in this
field.
2 Flags Attributes field, as described in section
4.2.2.
3..7 Filler Contains five octets of hex value FF.
8..15 SND_SEQ Sequence number field in clear text,
expressed in big-endian order.
16..last SGN_CKSUM Checksum of the "to-be-signed" data and
octet 0..15, as described in section 4.2.4.
that's 16bytes (GSS_KRB5_TOK_HDR_LEN) + chksum
wrap token
Octet no Name Description
--------------------------------------------------------------
0..1 TOK_ID Identification field. Tokens emitted by
GSS_Wrap() contain the hex value 05 04
expressed in big-endian order in this
field.
2 Flags Attributes field, as described in section
4.2.2.
3 Filler Contains the hex value FF.
4..5 EC Contains the "extra count" field, in big-
endian order as described in section 4.2.3.
6..7 RRC Contains the "right rotation count" in big-
endian order, as described in section
4.2.5.
8..15 SND_SEQ Sequence number field in clear text,
expressed in big-endian order.
16..last Data Encrypted data for Wrap tokens with
confidentiality, or plaintext data followed
by the checksum for Wrap tokens without
confidentiality, as described in section
4.2.4.
Also 16bytes of header (GSS_KRB5_TOK_HDR_LEN), encrypted data, and cksum
(other things like padding)
RFC 3961 defines known cksum sizes:
Checksum type sumtype checksum section or
value size reference
---------------------------------------------------------------------
CRC32 1 4 6.1.3
rsa-md4 2 16 6.1.2
rsa-md4-des 3 24 6.2.5
des-mac 4 16 6.2.7
des-mac-k 5 8 6.2.8
rsa-md4-des-k 6 16 6.2.6
rsa-md5 7 16 6.1.1
rsa-md5-des 8 24 6.2.4
rsa-md5-des3 9 24 ??
sha1 (unkeyed) 10 20 ??
hmac-sha1-des3-kd 12 20 6.3
hmac-sha1-des3 13 20 ??
sha1 (unkeyed) 14 20 ??
hmac-sha1-96-aes128 15 20 [KRB5-AES]
hmac-sha1-96-aes256 16 20 [KRB5-AES]
[reserved] 0x8003 ? [GSS-KRB5]
Linux kernel now mainly supports type 15,16 so max cksum size is 20bytes.
(GSS_KRB5_MAX_CKSUM_LEN)
Re-use already existing define of GSS_KRB5_MAX_SLACK_NEEDED that's used
for encoding the gss_wrap tokens (same tokens are used in reply).
Fixes: 2c94b8eca1a2 ("SUNRPC: Use au_rslack when computing reply buffer size")
Signed-off-by: Olga Kornievskaia <[email protected]>
---
net/sunrpc/auth_gss/auth_gss.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
index 24ca861..5a733a6 100644
--- a/net/sunrpc/auth_gss/auth_gss.c
+++ b/net/sunrpc/auth_gss/auth_gss.c
@@ -20,6 +20,7 @@
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/auth.h>
#include <linux/sunrpc/auth_gss.h>
+#include <linux/sunrpc/gss_krb5.h>
#include <linux/sunrpc/svcauth_gss.h>
#include <linux/sunrpc/gss_err.h>
#include <linux/workqueue.h>
@@ -51,6 +52,8 @@
/* length of a krb5 verifier (48), plus data added before arguments when
* using integrity (two 4-byte integers): */
#define GSS_VERF_SLACK 100
+/* covers lengths of gss_unwrap() extra kerberos mic and wrap token */
+#define GSS_RESP_SLACK (GSS_KRB5_MAX_SLACK_NEEDED << 2)
static DEFINE_HASHTABLE(gss_auth_hash_table, 4);
static DEFINE_SPINLOCK(gss_auth_hash_lock);
@@ -1050,7 +1053,7 @@ static void gss_pipe_free(struct gss_pipe *p)
goto err_put_mech;
auth = &gss_auth->rpc_auth;
auth->au_cslack = GSS_CRED_SLACK >> 2;
- auth->au_rslack = GSS_VERF_SLACK >> 2;
+ auth->au_rslack = GSS_RESP_SLACK >> 2;
auth->au_verfsize = GSS_VERF_SLACK >> 2;
auth->au_ralign = GSS_VERF_SLACK >> 2;
auth->au_flags = 0;
--
1.8.3.1
Hi Olga,
On Wed, 2020-03-25 at 17:01 -0400, Olga Kornievskaia wrote:
> From: Olga Kornievskaia <[email protected]>
>
> Ever since commit 2c94b8eca1a2 ("SUNRPC: Use au_rslack when computing
> reply buffer size"). It changed how "req->rq_rcvsize" is calculated.
> It
> used to use au_cslack value which was nice and large and changed it
> to
> au_rslack value which turns out to be too small.
>
> Since 5.1, v3 mount with sec=krb5p fails against an Ontap server
> because client's receive buffer it too small.
>
> For gss krb5p, we need to account for the mic token in the verifier,
> and the wrap token in the wrap token.
>
> RFC 4121 defines:
> mic token
> Octet no Name Description
> ----------------------------------------------------------
> ----
> 0..1 TOK_ID Identification field. Tokens emitted by
> GSS_GetMIC() contain the hex value 04 04
> expressed in big-endian order in this
> field.
> 2 Flags Attributes field, as described in
> section
> 4.2.2.
> 3..7 Filler Contains five octets of hex value FF.
> 8..15 SND_SEQ Sequence number field in clear text,
> expressed in big-endian order.
> 16..last SGN_CKSUM Checksum of the "to-be-signed" data and
> octet 0..15, as described in section
> 4.2.4.
>
> that's 16bytes (GSS_KRB5_TOK_HDR_LEN) + chksum
>
> wrap token
> Octet no Name Description
> ----------------------------------------------------------
> ----
> 0..1 TOK_ID Identification field. Tokens emitted by
> GSS_Wrap() contain the hex value 05 04
> expressed in big-endian order in this
> field.
> 2 Flags Attributes field, as described in
> section
> 4.2.2.
> 3 Filler Contains the hex value FF.
> 4..5 EC Contains the "extra count" field, in
> big-
> endian order as described in section
> 4.2.3.
> 6..7 RRC Contains the "right rotation count" in
> big-
> endian order, as described in section
> 4.2.5.
> 8..15 SND_SEQ Sequence number field in clear text,
> expressed in big-endian order.
> 16..last Data Encrypted data for Wrap tokens with
> confidentiality, or plaintext data
> followed
> by the checksum for Wrap tokens without
> confidentiality, as described in section
> 4.2.4.
>
> Also 16bytes of header (GSS_KRB5_TOK_HDR_LEN), encrypted data, and
> cksum
> (other things like padding)
>
> RFC 3961 defines known cksum sizes:
> Checksum type sumtype checksum section or
> value size referen
> ce
> ----------------------------------------------------------------
> -----
> CRC32 1 4 6.1.3
> rsa-md4 2 16 6.1.2
> rsa-md4-des 3 24 6.2.5
> des-mac 4 16 6.2.7
> des-mac-k 5 8 6.2.8
> rsa-md4-des-k 6 16 6.2.6
> rsa-md5 7 16 6.1.1
> rsa-md5-des 8 24 6.2.4
> rsa-md5-des3 9 24 ??
> sha1 (unkeyed) 10 20 ??
> hmac-sha1-des3-kd 12 20 6.3
> hmac-sha1-des3 13 20 ??
> sha1 (unkeyed) 14 20 ??
> hmac-sha1-96-aes128 15 20 [KRB5-
> AES]
> hmac-sha1-96-aes256 16 20 [KRB5-
> AES]
> [reserved] 0x8003 ? [GSS-
> KRB5]
>
> Linux kernel now mainly supports type 15,16 so max cksum size is
> 20bytes.
> (GSS_KRB5_MAX_CKSUM_LEN)
>
> Re-use already existing define of GSS_KRB5_MAX_SLACK_NEEDED that's
> used
> for encoding the gss_wrap tokens (same tokens are used in reply).
>
> Fixes: 2c94b8eca1a2 ("SUNRPC: Use au_rslack when computing reply
> buffer size")
> Signed-off-by: Olga Kornievskaia <[email protected]>
> ---
> net/sunrpc/auth_gss/auth_gss.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/net/sunrpc/auth_gss/auth_gss.c
> b/net/sunrpc/auth_gss/auth_gss.c
> index 24ca861..5a733a6 100644
> --- a/net/sunrpc/auth_gss/auth_gss.c
> +++ b/net/sunrpc/auth_gss/auth_gss.c
> @@ -20,6 +20,7 @@
> #include <linux/sunrpc/clnt.h>
> #include <linux/sunrpc/auth.h>
> #include <linux/sunrpc/auth_gss.h>
> +#include <linux/sunrpc/gss_krb5.h>
> #include <linux/sunrpc/svcauth_gss.h>
> #include <linux/sunrpc/gss_err.h>
> #include <linux/workqueue.h>
> @@ -51,6 +52,8 @@
> /* length of a krb5 verifier (48), plus data added before arguments
> when
> * using integrity (two 4-byte integers): */
> #define GSS_VERF_SLACK 100
> +/* covers lengths of gss_unwrap() extra kerberos mic and wrap token
> */
> +#define GSS_RESP_SLACK (GSS_KRB5_MAX_SLACK_NEEDED <<
> 2)
>
> static DEFINE_HASHTABLE(gss_auth_hash_table, 4);
> static DEFINE_SPINLOCK(gss_auth_hash_lock);
> @@ -1050,7 +1053,7 @@ static void gss_pipe_free(struct gss_pipe *p)
> goto err_put_mech;
> auth = &gss_auth->rpc_auth;
> auth->au_cslack = GSS_CRED_SLACK >> 2;
> - auth->au_rslack = GSS_VERF_SLACK >> 2;
> + auth->au_rslack = GSS_RESP_SLACK >> 2;
> auth->au_verfsize = GSS_VERF_SLACK >> 2;
> auth->au_ralign = GSS_VERF_SLACK >> 2;
> auth->au_flags = 0;
Is this a sufficient fix, though? It looks to me as if the above is
just an initial value that gets adjusted on the fly in
gss_unwrap_resp_priv():
auth->au_rslack = auth->au_verfsize + 2 +
XDR_QUADLEN(savedlen - rcv_buf->len);
auth->au_ralign = auth->au_verfsize + 2 +
XDR_QUADLEN(savedlen - rcv_buf->len);
My questions would be
- Are we sure that the above calculation (in gss_unwrap_resp_priv()) is
correct?
- Are we sure that the above calculation always gives the same answer
over time? We probably should not store a value that keeps changing.
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
[email protected]
> On Mar 25, 2020, at 5:01 PM, Olga Kornievskaia <[email protected]> wrote:
>
> From: Olga Kornievskaia <[email protected]>
>
> Ever since commit 2c94b8eca1a2 ("SUNRPC: Use au_rslack when computing
> reply buffer size"). It changed how "req->rq_rcvsize" is calculated. It
> used to use au_cslack value which was nice and large and changed it to
> au_rslack value which turns out to be too small.
>
> Since 5.1, v3 mount with sec=krb5p fails against an Ontap server
> because client's receive buffer it too small.
>
> For gss krb5p, we need to account for the mic token in the verifier,
> and the wrap token in the wrap token.
>
> RFC 4121 defines:
> mic token
> Octet no Name Description
> --------------------------------------------------------------
> 0..1 TOK_ID Identification field. Tokens emitted by
> GSS_GetMIC() contain the hex value 04 04
> expressed in big-endian order in this
> field.
> 2 Flags Attributes field, as described in section
> 4.2.2.
> 3..7 Filler Contains five octets of hex value FF.
> 8..15 SND_SEQ Sequence number field in clear text,
> expressed in big-endian order.
> 16..last SGN_CKSUM Checksum of the "to-be-signed" data and
> octet 0..15, as described in section 4.2.4.
>
> that's 16bytes (GSS_KRB5_TOK_HDR_LEN) + chksum
>
> wrap token
> Octet no Name Description
> --------------------------------------------------------------
> 0..1 TOK_ID Identification field. Tokens emitted by
> GSS_Wrap() contain the hex value 05 04
> expressed in big-endian order in this
> field.
> 2 Flags Attributes field, as described in section
> 4.2.2.
> 3 Filler Contains the hex value FF.
> 4..5 EC Contains the "extra count" field, in big-
> endian order as described in section 4.2.3.
> 6..7 RRC Contains the "right rotation count" in big-
> endian order, as described in section
> 4.2.5.
> 8..15 SND_SEQ Sequence number field in clear text,
> expressed in big-endian order.
> 16..last Data Encrypted data for Wrap tokens with
> confidentiality, or plaintext data followed
> by the checksum for Wrap tokens without
> confidentiality, as described in section
> 4.2.4.
>
> Also 16bytes of header (GSS_KRB5_TOK_HDR_LEN), encrypted data, and cksum
> (other things like padding)
>
> RFC 3961 defines known cksum sizes:
> Checksum type sumtype checksum section or
> value size reference
> ---------------------------------------------------------------------
> CRC32 1 4 6.1.3
> rsa-md4 2 16 6.1.2
> rsa-md4-des 3 24 6.2.5
> des-mac 4 16 6.2.7
> des-mac-k 5 8 6.2.8
> rsa-md4-des-k 6 16 6.2.6
> rsa-md5 7 16 6.1.1
> rsa-md5-des 8 24 6.2.4
> rsa-md5-des3 9 24 ??
> sha1 (unkeyed) 10 20 ??
> hmac-sha1-des3-kd 12 20 6.3
> hmac-sha1-des3 13 20 ??
> sha1 (unkeyed) 14 20 ??
> hmac-sha1-96-aes128 15 20 [KRB5-AES]
> hmac-sha1-96-aes256 16 20 [KRB5-AES]
> [reserved] 0x8003 ? [GSS-KRB5]
>
> Linux kernel now mainly supports type 15,16 so max cksum size is 20bytes.
> (GSS_KRB5_MAX_CKSUM_LEN)
>
> Re-use already existing define of GSS_KRB5_MAX_SLACK_NEEDED that's used
> for encoding the gss_wrap tokens (same tokens are used in reply).
>
> Fixes: 2c94b8eca1a2 ("SUNRPC: Use au_rslack when computing reply buffer size")
> Signed-off-by: Olga Kornievskaia <[email protected]>
> ---
> net/sunrpc/auth_gss/auth_gss.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
> index 24ca861..5a733a6 100644
> --- a/net/sunrpc/auth_gss/auth_gss.c
> +++ b/net/sunrpc/auth_gss/auth_gss.c
> @@ -20,6 +20,7 @@
> #include <linux/sunrpc/clnt.h>
> #include <linux/sunrpc/auth.h>
> #include <linux/sunrpc/auth_gss.h>
> +#include <linux/sunrpc/gss_krb5.h>
> #include <linux/sunrpc/svcauth_gss.h>
> #include <linux/sunrpc/gss_err.h>
> #include <linux/workqueue.h>
> @@ -51,6 +52,8 @@
> /* length of a krb5 verifier (48), plus data added before arguments when
> * using integrity (two 4-byte integers): */
> #define GSS_VERF_SLACK 100
> +/* covers lengths of gss_unwrap() extra kerberos mic and wrap token */
> +#define GSS_RESP_SLACK (GSS_KRB5_MAX_SLACK_NEEDED << 2)
GSS_KRB5_MAX_SLACK_NEEDED is already in bytes. Shouldn't need the "<< 2" here.
> static DEFINE_HASHTABLE(gss_auth_hash_table, 4);
> static DEFINE_SPINLOCK(gss_auth_hash_lock);
> @@ -1050,7 +1053,7 @@ static void gss_pipe_free(struct gss_pipe *p)
> goto err_put_mech;
> auth = &gss_auth->rpc_auth;
> auth->au_cslack = GSS_CRED_SLACK >> 2;
> - auth->au_rslack = GSS_VERF_SLACK >> 2;
> + auth->au_rslack = GSS_RESP_SLACK >> 2;
> auth->au_verfsize = GSS_VERF_SLACK >> 2;
> auth->au_ralign = GSS_VERF_SLACK >> 2;
> auth->au_flags = 0;
> --
> 1.8.3.1
>
--
Chuck Lever
> On Mar 25, 2020, at 5:33 PM, Trond Myklebust <[email protected]> wrote:
>
> Hi Olga,
>
> On Wed, 2020-03-25 at 17:01 -0400, Olga Kornievskaia wrote:
>> From: Olga Kornievskaia <[email protected]>
>>
>> Ever since commit 2c94b8eca1a2 ("SUNRPC: Use au_rslack when computing
>> reply buffer size"). It changed how "req->rq_rcvsize" is calculated.
>> It
>> used to use au_cslack value which was nice and large and changed it
>> to
>> au_rslack value which turns out to be too small.
>>
>> Since 5.1, v3 mount with sec=krb5p fails against an Ontap server
>> because client's receive buffer it too small.
>>
>> For gss krb5p, we need to account for the mic token in the verifier,
>> and the wrap token in the wrap token.
>>
>> RFC 4121 defines:
>> mic token
>> Octet no Name Description
>> ----------------------------------------------------------
>> ----
>> 0..1 TOK_ID Identification field. Tokens emitted by
>> GSS_GetMIC() contain the hex value 04 04
>> expressed in big-endian order in this
>> field.
>> 2 Flags Attributes field, as described in
>> section
>> 4.2.2.
>> 3..7 Filler Contains five octets of hex value FF.
>> 8..15 SND_SEQ Sequence number field in clear text,
>> expressed in big-endian order.
>> 16..last SGN_CKSUM Checksum of the "to-be-signed" data and
>> octet 0..15, as described in section
>> 4.2.4.
>>
>> that's 16bytes (GSS_KRB5_TOK_HDR_LEN) + chksum
>>
>> wrap token
>> Octet no Name Description
>> ----------------------------------------------------------
>> ----
>> 0..1 TOK_ID Identification field. Tokens emitted by
>> GSS_Wrap() contain the hex value 05 04
>> expressed in big-endian order in this
>> field.
>> 2 Flags Attributes field, as described in
>> section
>> 4.2.2.
>> 3 Filler Contains the hex value FF.
>> 4..5 EC Contains the "extra count" field, in
>> big-
>> endian order as described in section
>> 4.2.3.
>> 6..7 RRC Contains the "right rotation count" in
>> big-
>> endian order, as described in section
>> 4.2.5.
>> 8..15 SND_SEQ Sequence number field in clear text,
>> expressed in big-endian order.
>> 16..last Data Encrypted data for Wrap tokens with
>> confidentiality, or plaintext data
>> followed
>> by the checksum for Wrap tokens without
>> confidentiality, as described in section
>> 4.2.4.
>>
>> Also 16bytes of header (GSS_KRB5_TOK_HDR_LEN), encrypted data, and
>> cksum
>> (other things like padding)
>>
>> RFC 3961 defines known cksum sizes:
>> Checksum type sumtype checksum section or
>> value size referen
>> ce
>> ----------------------------------------------------------------
>> -----
>> CRC32 1 4 6.1.3
>> rsa-md4 2 16 6.1.2
>> rsa-md4-des 3 24 6.2.5
>> des-mac 4 16 6.2.7
>> des-mac-k 5 8 6.2.8
>> rsa-md4-des-k 6 16 6.2.6
>> rsa-md5 7 16 6.1.1
>> rsa-md5-des 8 24 6.2.4
>> rsa-md5-des3 9 24 ??
>> sha1 (unkeyed) 10 20 ??
>> hmac-sha1-des3-kd 12 20 6.3
>> hmac-sha1-des3 13 20 ??
>> sha1 (unkeyed) 14 20 ??
>> hmac-sha1-96-aes128 15 20 [KRB5-
>> AES]
>> hmac-sha1-96-aes256 16 20 [KRB5-
>> AES]
>> [reserved] 0x8003 ? [GSS-
>> KRB5]
>>
>> Linux kernel now mainly supports type 15,16 so max cksum size is
>> 20bytes.
>> (GSS_KRB5_MAX_CKSUM_LEN)
>>
>> Re-use already existing define of GSS_KRB5_MAX_SLACK_NEEDED that's
>> used
>> for encoding the gss_wrap tokens (same tokens are used in reply).
>>
>> Fixes: 2c94b8eca1a2 ("SUNRPC: Use au_rslack when computing reply
>> buffer size")
>> Signed-off-by: Olga Kornievskaia <[email protected]>
>> ---
>> net/sunrpc/auth_gss/auth_gss.c | 5 ++++-
>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/net/sunrpc/auth_gss/auth_gss.c
>> b/net/sunrpc/auth_gss/auth_gss.c
>> index 24ca861..5a733a6 100644
>> --- a/net/sunrpc/auth_gss/auth_gss.c
>> +++ b/net/sunrpc/auth_gss/auth_gss.c
>> @@ -20,6 +20,7 @@
>> #include <linux/sunrpc/clnt.h>
>> #include <linux/sunrpc/auth.h>
>> #include <linux/sunrpc/auth_gss.h>
>> +#include <linux/sunrpc/gss_krb5.h>
>> #include <linux/sunrpc/svcauth_gss.h>
>> #include <linux/sunrpc/gss_err.h>
>> #include <linux/workqueue.h>
>> @@ -51,6 +52,8 @@
>> /* length of a krb5 verifier (48), plus data added before arguments
>> when
>> * using integrity (two 4-byte integers): */
>> #define GSS_VERF_SLACK 100
>> +/* covers lengths of gss_unwrap() extra kerberos mic and wrap token
>> */
>> +#define GSS_RESP_SLACK (GSS_KRB5_MAX_SLACK_NEEDED <<
>> 2)
>>
>> static DEFINE_HASHTABLE(gss_auth_hash_table, 4);
>> static DEFINE_SPINLOCK(gss_auth_hash_lock);
>> @@ -1050,7 +1053,7 @@ static void gss_pipe_free(struct gss_pipe *p)
>> goto err_put_mech;
>> auth = &gss_auth->rpc_auth;
>> auth->au_cslack = GSS_CRED_SLACK >> 2;
>> - auth->au_rslack = GSS_VERF_SLACK >> 2;
>> + auth->au_rslack = GSS_RESP_SLACK >> 2;
>> auth->au_verfsize = GSS_VERF_SLACK >> 2;
>> auth->au_ralign = GSS_VERF_SLACK >> 2;
>> auth->au_flags = 0;
>
> Is this a sufficient fix, though? It looks to me as if the above is
> just an initial value that gets adjusted on the fly in
> gss_unwrap_resp_priv():
>
> auth->au_rslack = auth->au_verfsize + 2 +
> XDR_QUADLEN(savedlen - rcv_buf->len);
> auth->au_ralign = auth->au_verfsize + 2 +
> XDR_QUADLEN(savedlen - rcv_buf->len);
That's correct. The GSS_*_SLACK value is a _sz value that is
the largest possible expected size of the extra GSS data.
> My questions would be
>
> - Are we sure that the above calculation (in gss_unwrap_resp_priv()) is
> correct?
Yes, this is the correct computation.
We know this because if the initial au_rslack value is large
enough, then subsequent Replies have the correct amount of buffer
space and always succeed.
> - Are we sure that the above calculation always gives the same answer
> over time? We probably should not store a value that keeps changing.
It does not change after the first Reply. au_rslack is typically
adjusted downwards from the initial value based on the size of the
first received Reply.
Not setting these variables after the first Reply has been received
would be a minor optimization that could be done after Olga's fix.
--
Chuck Lever
On Wed, 2020-03-25 at 17:43 -0400, Chuck Lever wrote:
> > On Mar 25, 2020, at 5:33 PM, Trond Myklebust <
> > [email protected]> wrote:
> >
> > Hi Olga,
> >
> > On Wed, 2020-03-25 at 17:01 -0400, Olga Kornievskaia wrote:
> > > From: Olga Kornievskaia <[email protected]>
> > >
> > > Ever since commit 2c94b8eca1a2 ("SUNRPC: Use au_rslack when
> > > computing
> > > reply buffer size"). It changed how "req->rq_rcvsize" is
> > > calculated.
> > > It
> > > used to use au_cslack value which was nice and large and changed
> > > it
> > > to
> > > au_rslack value which turns out to be too small.
> > >
> > > Since 5.1, v3 mount with sec=krb5p fails against an Ontap server
> > > because client's receive buffer it too small.
> > >
> > > For gss krb5p, we need to account for the mic token in the
> > > verifier,
> > > and the wrap token in the wrap token.
> > >
> > > RFC 4121 defines:
> > > mic token
> > > Octet no Name Description
> > > ---------------------------------------------------------
> > > -
> > > ----
> > > 0..1 TOK_ID Identification field. Tokens emitted
> > > by
> > > GSS_GetMIC() contain the hex value 04
> > > 04
> > > expressed in big-endian order in this
> > > field.
> > > 2 Flags Attributes field, as described in
> > > section
> > > 4.2.2.
> > > 3..7 Filler Contains five octets of hex value FF.
> > > 8..15 SND_SEQ Sequence number field in clear text,
> > > expressed in big-endian order.
> > > 16..last SGN_CKSUM Checksum of the "to-be-signed" data
> > > and
> > > octet 0..15, as described in section
> > > 4.2.4.
> > >
> > > that's 16bytes (GSS_KRB5_TOK_HDR_LEN) + chksum
> > >
> > > wrap token
> > > Octet no Name Description
> > > ---------------------------------------------------------
> > > -
> > > ----
> > > 0..1 TOK_ID Identification field. Tokens emitted
> > > by
> > > GSS_Wrap() contain the hex value 05
> > > 04
> > > expressed in big-endian order in this
> > > field.
> > > 2 Flags Attributes field, as described in
> > > section
> > > 4.2.2.
> > > 3 Filler Contains the hex value FF.
> > > 4..5 EC Contains the "extra count" field, in
> > > big-
> > > endian order as described in section
> > > 4.2.3.
> > > 6..7 RRC Contains the "right rotation count"
> > > in
> > > big-
> > > endian order, as described in section
> > > 4.2.5.
> > > 8..15 SND_SEQ Sequence number field in clear text,
> > > expressed in big-endian order.
> > > 16..last Data Encrypted data for Wrap tokens with
> > > confidentiality, or plaintext data
> > > followed
> > > by the checksum for Wrap tokens
> > > without
> > > confidentiality, as described in
> > > section
> > > 4.2.4.
> > >
> > > Also 16bytes of header (GSS_KRB5_TOK_HDR_LEN), encrypted data,
> > > and
> > > cksum
> > > (other things like padding)
> > >
> > > RFC 3961 defines known cksum sizes:
> > > Checksum
> > > type sumtype checksum section or
> > > value size refe
> > > ren
> > > ce
> > > -------------------------------------------------------------
> > > ---
> > > -----
> > >
> > > CRC32 1 4 6.1.
> > > 3
> > > rsa-
> > > md4 2 16 6.1.2
> > > rsa-md4-
> > > des 3 24 6.2.5
> > > des-
> > > mac 4 16 6.2.7
> > > des-mac-
> > > k 5 8 6.2.8
> > > rsa-md4-des-
> > > k 6 16 6.2.6
> > > rsa-
> > > md5 7 16 6.1.1
> > > rsa-md5-
> > > des 8 24 6.2.4
> > > rsa-md5-
> > > des3 9 24 ??
> > > sha1
> > > (unkeyed) 10 20 ??
> > > hmac-sha1-des3-
> > > kd 12 20 6.3
> > > hmac-sha1-
> > > des3 13 20 ??
> > > sha1
> > > (unkeyed) 14 20 ??
> > > hmac-sha1-96-
> > > aes128 15 20 [KRB5-
> > > AES]
> > > hmac-sha1-96-
> > > aes256 16 20 [KRB5-
> > > AES]
> > >
> > > [reserved] 0x8003 ? [GSS-
> > > KRB5]
> > >
> > > Linux kernel now mainly supports type 15,16 so max cksum size is
> > > 20bytes.
> > > (GSS_KRB5_MAX_CKSUM_LEN)
> > >
> > > Re-use already existing define of GSS_KRB5_MAX_SLACK_NEEDED
> > > that's
> > > used
> > > for encoding the gss_wrap tokens (same tokens are used in reply).
> > >
> > > Fixes: 2c94b8eca1a2 ("SUNRPC: Use au_rslack when computing reply
> > > buffer size")
> > > Signed-off-by: Olga Kornievskaia <[email protected]>
> > > ---
> > > net/sunrpc/auth_gss/auth_gss.c | 5 ++++-
> > > 1 file changed, 4 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/net/sunrpc/auth_gss/auth_gss.c
> > > b/net/sunrpc/auth_gss/auth_gss.c
> > > index 24ca861..5a733a6 100644
> > > --- a/net/sunrpc/auth_gss/auth_gss.c
> > > +++ b/net/sunrpc/auth_gss/auth_gss.c
> > > @@ -20,6 +20,7 @@
> > > #include <linux/sunrpc/clnt.h>
> > > #include <linux/sunrpc/auth.h>
> > > #include <linux/sunrpc/auth_gss.h>
> > > +#include <linux/sunrpc/gss_krb5.h>
> > > #include <linux/sunrpc/svcauth_gss.h>
> > > #include <linux/sunrpc/gss_err.h>
> > > #include <linux/workqueue.h>
> > > @@ -51,6 +52,8 @@
> > > /* length of a krb5 verifier (48), plus data added before
> > > arguments
> > > when
> > > * using integrity (two 4-byte integers): */
> > > #define GSS_VERF_SLACK 100
> > > +/* covers lengths of gss_unwrap() extra kerberos mic and wrap
> > > token
> > > */
> > > +#define GSS_RESP_SLACK (GSS_KRB5_MAX_SLACK_NEEDED <<
> > > 2)
> > >
> > > static DEFINE_HASHTABLE(gss_auth_hash_table, 4);
> > > static DEFINE_SPINLOCK(gss_auth_hash_lock);
> > > @@ -1050,7 +1053,7 @@ static void gss_pipe_free(struct gss_pipe
> > > *p)
> > > goto err_put_mech;
> > > auth = &gss_auth->rpc_auth;
> > > auth->au_cslack = GSS_CRED_SLACK >> 2;
> > > - auth->au_rslack = GSS_VERF_SLACK >> 2;
> > > + auth->au_rslack = GSS_RESP_SLACK >> 2;
> > > auth->au_verfsize = GSS_VERF_SLACK >> 2;
> > > auth->au_ralign = GSS_VERF_SLACK >> 2;
> > > auth->au_flags = 0;
> >
> > Is this a sufficient fix, though? It looks to me as if the above is
> > just an initial value that gets adjusted on the fly in
> > gss_unwrap_resp_priv():
> >
> > auth->au_rslack = auth->au_verfsize + 2 +
> > XDR_QUADLEN(savedlen - rcv_buf->len);
> > auth->au_ralign = auth->au_verfsize + 2 +
> > XDR_QUADLEN(savedlen - rcv_buf->len);
>
> That's correct. The GSS_*_SLACK value is a _sz value that is
> the largest possible expected size of the extra GSS data.
>
>
> > My questions would be
> >
> > - Are we sure that the above calculation (in
> > gss_unwrap_resp_priv()) is
> > correct?
>
> Yes, this is the correct computation.
>
> We know this because if the initial au_rslack value is large
> enough, then subsequent Replies have the correct amount of buffer
> space and always succeed.
>
>
> > - Are we sure that the above calculation always gives the same
> > answer
> > over time? We probably should not store a value that keeps
> > changing.
>
> It does not change after the first Reply. au_rslack is typically
> adjusted downwards from the initial value based on the size of the
> first received Reply.
>
> Not setting these variables after the first Reply has been received
> would be a minor optimization that could be done after Olga's fix.
>
OK. So you're both saying that as long as the initial value is correct,
we're good for the duration of the GSS session? Fair enough, I'll apply
this patch for 5.7 then.
Let's also fix up the above in a separate patch to not keep setting
auth->au_rslack / auth->au_ralign if their values are not changing.
That should prevent unnecessary cache line bouncing.
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
[email protected]
> On Mar 25, 2020, at 5:52 PM, Trond Myklebust <[email protected]> wrote:
>
> On Wed, 2020-03-25 at 17:43 -0400, Chuck Lever wrote:
>>> On Mar 25, 2020, at 5:33 PM, Trond Myklebust <
>>> [email protected]> wrote:
>>>
>>> Hi Olga,
>>>
>>> On Wed, 2020-03-25 at 17:01 -0400, Olga Kornievskaia wrote:
>>>> From: Olga Kornievskaia <[email protected]>
>>>>
>>>> Ever since commit 2c94b8eca1a2 ("SUNRPC: Use au_rslack when
>>>> computing
>>>> reply buffer size"). It changed how "req->rq_rcvsize" is
>>>> calculated.
>>>> It
>>>> used to use au_cslack value which was nice and large and changed
>>>> it
>>>> to
>>>> au_rslack value which turns out to be too small.
>>>>
>>>> Since 5.1, v3 mount with sec=krb5p fails against an Ontap server
>>>> because client's receive buffer it too small.
>>>>
>>>> For gss krb5p, we need to account for the mic token in the
>>>> verifier,
>>>> and the wrap token in the wrap token.
>>>>
>>>> RFC 4121 defines:
>>>> mic token
>>>> Octet no Name Description
>>>> ---------------------------------------------------------
>>>> -
>>>> ----
>>>> 0..1 TOK_ID Identification field. Tokens emitted
>>>> by
>>>> GSS_GetMIC() contain the hex value 04
>>>> 04
>>>> expressed in big-endian order in this
>>>> field.
>>>> 2 Flags Attributes field, as described in
>>>> section
>>>> 4.2.2.
>>>> 3..7 Filler Contains five octets of hex value FF.
>>>> 8..15 SND_SEQ Sequence number field in clear text,
>>>> expressed in big-endian order.
>>>> 16..last SGN_CKSUM Checksum of the "to-be-signed" data
>>>> and
>>>> octet 0..15, as described in section
>>>> 4.2.4.
>>>>
>>>> that's 16bytes (GSS_KRB5_TOK_HDR_LEN) + chksum
>>>>
>>>> wrap token
>>>> Octet no Name Description
>>>> ---------------------------------------------------------
>>>> -
>>>> ----
>>>> 0..1 TOK_ID Identification field. Tokens emitted
>>>> by
>>>> GSS_Wrap() contain the hex value 05
>>>> 04
>>>> expressed in big-endian order in this
>>>> field.
>>>> 2 Flags Attributes field, as described in
>>>> section
>>>> 4.2.2.
>>>> 3 Filler Contains the hex value FF.
>>>> 4..5 EC Contains the "extra count" field, in
>>>> big-
>>>> endian order as described in section
>>>> 4.2.3.
>>>> 6..7 RRC Contains the "right rotation count"
>>>> in
>>>> big-
>>>> endian order, as described in section
>>>> 4.2.5.
>>>> 8..15 SND_SEQ Sequence number field in clear text,
>>>> expressed in big-endian order.
>>>> 16..last Data Encrypted data for Wrap tokens with
>>>> confidentiality, or plaintext data
>>>> followed
>>>> by the checksum for Wrap tokens
>>>> without
>>>> confidentiality, as described in
>>>> section
>>>> 4.2.4.
>>>>
>>>> Also 16bytes of header (GSS_KRB5_TOK_HDR_LEN), encrypted data,
>>>> and
>>>> cksum
>>>> (other things like padding)
>>>>
>>>> RFC 3961 defines known cksum sizes:
>>>> Checksum
>>>> type sumtype checksum section or
>>>> value size refe
>>>> ren
>>>> ce
>>>> -------------------------------------------------------------
>>>> ---
>>>> -----
>>>>
>>>> CRC32 1 4 6.1.
>>>> 3
>>>> rsa-
>>>> md4 2 16 6.1.2
>>>> rsa-md4-
>>>> des 3 24 6.2.5
>>>> des-
>>>> mac 4 16 6.2.7
>>>> des-mac-
>>>> k 5 8 6.2.8
>>>> rsa-md4-des-
>>>> k 6 16 6.2.6
>>>> rsa-
>>>> md5 7 16 6.1.1
>>>> rsa-md5-
>>>> des 8 24 6.2.4
>>>> rsa-md5-
>>>> des3 9 24 ??
>>>> sha1
>>>> (unkeyed) 10 20 ??
>>>> hmac-sha1-des3-
>>>> kd 12 20 6.3
>>>> hmac-sha1-
>>>> des3 13 20 ??
>>>> sha1
>>>> (unkeyed) 14 20 ??
>>>> hmac-sha1-96-
>>>> aes128 15 20 [KRB5-
>>>> AES]
>>>> hmac-sha1-96-
>>>> aes256 16 20 [KRB5-
>>>> AES]
>>>>
>>>> [reserved] 0x8003 ? [GSS-
>>>> KRB5]
>>>>
>>>> Linux kernel now mainly supports type 15,16 so max cksum size is
>>>> 20bytes.
>>>> (GSS_KRB5_MAX_CKSUM_LEN)
>>>>
>>>> Re-use already existing define of GSS_KRB5_MAX_SLACK_NEEDED
>>>> that's
>>>> used
>>>> for encoding the gss_wrap tokens (same tokens are used in reply).
>>>>
>>>> Fixes: 2c94b8eca1a2 ("SUNRPC: Use au_rslack when computing reply
>>>> buffer size")
>>>> Signed-off-by: Olga Kornievskaia <[email protected]>
>>>> ---
>>>> net/sunrpc/auth_gss/auth_gss.c | 5 ++++-
>>>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/net/sunrpc/auth_gss/auth_gss.c
>>>> b/net/sunrpc/auth_gss/auth_gss.c
>>>> index 24ca861..5a733a6 100644
>>>> --- a/net/sunrpc/auth_gss/auth_gss.c
>>>> +++ b/net/sunrpc/auth_gss/auth_gss.c
>>>> @@ -20,6 +20,7 @@
>>>> #include <linux/sunrpc/clnt.h>
>>>> #include <linux/sunrpc/auth.h>
>>>> #include <linux/sunrpc/auth_gss.h>
>>>> +#include <linux/sunrpc/gss_krb5.h>
>>>> #include <linux/sunrpc/svcauth_gss.h>
>>>> #include <linux/sunrpc/gss_err.h>
>>>> #include <linux/workqueue.h>
>>>> @@ -51,6 +52,8 @@
>>>> /* length of a krb5 verifier (48), plus data added before
>>>> arguments
>>>> when
>>>> * using integrity (two 4-byte integers): */
>>>> #define GSS_VERF_SLACK 100
>>>> +/* covers lengths of gss_unwrap() extra kerberos mic and wrap
>>>> token
>>>> */
>>>> +#define GSS_RESP_SLACK (GSS_KRB5_MAX_SLACK_NEEDED <<
>>>> 2)
>>>>
>>>> static DEFINE_HASHTABLE(gss_auth_hash_table, 4);
>>>> static DEFINE_SPINLOCK(gss_auth_hash_lock);
>>>> @@ -1050,7 +1053,7 @@ static void gss_pipe_free(struct gss_pipe
>>>> *p)
>>>> goto err_put_mech;
>>>> auth = &gss_auth->rpc_auth;
>>>> auth->au_cslack = GSS_CRED_SLACK >> 2;
>>>> - auth->au_rslack = GSS_VERF_SLACK >> 2;
>>>> + auth->au_rslack = GSS_RESP_SLACK >> 2;
>>>> auth->au_verfsize = GSS_VERF_SLACK >> 2;
>>>> auth->au_ralign = GSS_VERF_SLACK >> 2;
>>>> auth->au_flags = 0;
>>>
>>> Is this a sufficient fix, though? It looks to me as if the above is
>>> just an initial value that gets adjusted on the fly in
>>> gss_unwrap_resp_priv():
>>>
>>> auth->au_rslack = auth->au_verfsize + 2 +
>>> XDR_QUADLEN(savedlen - rcv_buf->len);
>>> auth->au_ralign = auth->au_verfsize + 2 +
>>> XDR_QUADLEN(savedlen - rcv_buf->len);
>>
>> That's correct. The GSS_*_SLACK value is a _sz value that is
>> the largest possible expected size of the extra GSS data.
>>
>>
>>> My questions would be
>>>
>>> - Are we sure that the above calculation (in
>>> gss_unwrap_resp_priv()) is
>>> correct?
>>
>> Yes, this is the correct computation.
>>
>> We know this because if the initial au_rslack value is large
>> enough, then subsequent Replies have the correct amount of buffer
>> space and always succeed.
>>
>>
>>> - Are we sure that the above calculation always gives the same
>>> answer
>>> over time? We probably should not store a value that keeps
>>> changing.
>>
>> It does not change after the first Reply. au_rslack is typically
>> adjusted downwards from the initial value based on the size of the
>> first received Reply.
>>
>> Not setting these variables after the first Reply has been received
>> would be a minor optimization that could be done after Olga's fix.
>>
>
> OK. So you're both saying that as long as the initial value is correct,
> we're good for the duration of the GSS session? Fair enough, I'll apply
> this patch for 5.7 then.
Thanks, please see my one-line correction. I think the definition of
GSS_RESP_SLACK should not include the "<< 2", I would like Olga to
confirm.
> Let's also fix up the above in a separate patch to not keep setting
> auth->au_rslack / auth->au_ralign if their values are not changing.
> That should prevent unnecessary cache line bouncing.
I volunteer, unless Olga wants to take it.
--
Chuck Lever
On Wed, Mar 25, 2020 at 5:34 PM Chuck Lever <[email protected]> wrote:
>
>
>
> > On Mar 25, 2020, at 5:01 PM, Olga Kornievskaia <[email protected]> wrote:
> >
> > From: Olga Kornievskaia <[email protected]>
> >
> > Ever since commit 2c94b8eca1a2 ("SUNRPC: Use au_rslack when computing
> > reply buffer size"). It changed how "req->rq_rcvsize" is calculated. It
> > used to use au_cslack value which was nice and large and changed it to
> > au_rslack value which turns out to be too small.
> >
> > Since 5.1, v3 mount with sec=krb5p fails against an Ontap server
> > because client's receive buffer it too small.
> >
> > For gss krb5p, we need to account for the mic token in the verifier,
> > and the wrap token in the wrap token.
> >
> > RFC 4121 defines:
> > mic token
> > Octet no Name Description
> > --------------------------------------------------------------
> > 0..1 TOK_ID Identification field. Tokens emitted by
> > GSS_GetMIC() contain the hex value 04 04
> > expressed in big-endian order in this
> > field.
> > 2 Flags Attributes field, as described in section
> > 4.2.2.
> > 3..7 Filler Contains five octets of hex value FF.
> > 8..15 SND_SEQ Sequence number field in clear text,
> > expressed in big-endian order.
> > 16..last SGN_CKSUM Checksum of the "to-be-signed" data and
> > octet 0..15, as described in section 4.2.4.
> >
> > that's 16bytes (GSS_KRB5_TOK_HDR_LEN) + chksum
> >
> > wrap token
> > Octet no Name Description
> > --------------------------------------------------------------
> > 0..1 TOK_ID Identification field. Tokens emitted by
> > GSS_Wrap() contain the hex value 05 04
> > expressed in big-endian order in this
> > field.
> > 2 Flags Attributes field, as described in section
> > 4.2.2.
> > 3 Filler Contains the hex value FF.
> > 4..5 EC Contains the "extra count" field, in big-
> > endian order as described in section 4.2.3.
> > 6..7 RRC Contains the "right rotation count" in big-
> > endian order, as described in section
> > 4.2.5.
> > 8..15 SND_SEQ Sequence number field in clear text,
> > expressed in big-endian order.
> > 16..last Data Encrypted data for Wrap tokens with
> > confidentiality, or plaintext data followed
> > by the checksum for Wrap tokens without
> > confidentiality, as described in section
> > 4.2.4.
> >
> > Also 16bytes of header (GSS_KRB5_TOK_HDR_LEN), encrypted data, and cksum
> > (other things like padding)
> >
> > RFC 3961 defines known cksum sizes:
> > Checksum type sumtype checksum section or
> > value size reference
> > ---------------------------------------------------------------------
> > CRC32 1 4 6.1.3
> > rsa-md4 2 16 6.1.2
> > rsa-md4-des 3 24 6.2.5
> > des-mac 4 16 6.2.7
> > des-mac-k 5 8 6.2.8
> > rsa-md4-des-k 6 16 6.2.6
> > rsa-md5 7 16 6.1.1
> > rsa-md5-des 8 24 6.2.4
> > rsa-md5-des3 9 24 ??
> > sha1 (unkeyed) 10 20 ??
> > hmac-sha1-des3-kd 12 20 6.3
> > hmac-sha1-des3 13 20 ??
> > sha1 (unkeyed) 14 20 ??
> > hmac-sha1-96-aes128 15 20 [KRB5-AES]
> > hmac-sha1-96-aes256 16 20 [KRB5-AES]
> > [reserved] 0x8003 ? [GSS-KRB5]
> >
> > Linux kernel now mainly supports type 15,16 so max cksum size is 20bytes.
> > (GSS_KRB5_MAX_CKSUM_LEN)
> >
> > Re-use already existing define of GSS_KRB5_MAX_SLACK_NEEDED that's used
> > for encoding the gss_wrap tokens (same tokens are used in reply).
> >
> > Fixes: 2c94b8eca1a2 ("SUNRPC: Use au_rslack when computing reply buffer size")
> > Signed-off-by: Olga Kornievskaia <[email protected]>
> > ---
> > net/sunrpc/auth_gss/auth_gss.c | 5 ++++-
> > 1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
> > index 24ca861..5a733a6 100644
> > --- a/net/sunrpc/auth_gss/auth_gss.c
> > +++ b/net/sunrpc/auth_gss/auth_gss.c
> > @@ -20,6 +20,7 @@
> > #include <linux/sunrpc/clnt.h>
> > #include <linux/sunrpc/auth.h>
> > #include <linux/sunrpc/auth_gss.h>
> > +#include <linux/sunrpc/gss_krb5.h>
> > #include <linux/sunrpc/svcauth_gss.h>
> > #include <linux/sunrpc/gss_err.h>
> > #include <linux/workqueue.h>
> > @@ -51,6 +52,8 @@
> > /* length of a krb5 verifier (48), plus data added before arguments when
> > * using integrity (two 4-byte integers): */
> > #define GSS_VERF_SLACK 100
> > +/* covers lengths of gss_unwrap() extra kerberos mic and wrap token */
> > +#define GSS_RESP_SLACK (GSS_KRB5_MAX_SLACK_NEEDED << 2)
>
> GSS_KRB5_MAX_SLACK_NEEDED is already in bytes. Shouldn't need the "<< 2" here.
Ok yes just for my own understanding I convinced myself that indeed
"<<2" is not needed here because clnt.c will do rq_rcvsize is <<=2.
Now question: Do I even need to introduce GSS_RES_SLACK at all or
perhaps just use GSS_KRB5_MAX_SLACK_NEEDED to initialize?
> > static DEFINE_HASHTABLE(gss_auth_hash_table, 4);
> > static DEFINE_SPINLOCK(gss_auth_hash_lock);
> > @@ -1050,7 +1053,7 @@ static void gss_pipe_free(struct gss_pipe *p)
> > goto err_put_mech;
> > auth = &gss_auth->rpc_auth;
> > auth->au_cslack = GSS_CRED_SLACK >> 2;
> > - auth->au_rslack = GSS_VERF_SLACK >> 2;
> > + auth->au_rslack = GSS_RESP_SLACK >> 2;
> > auth->au_verfsize = GSS_VERF_SLACK >> 2;
> > auth->au_ralign = GSS_VERF_SLACK >> 2;
> > auth->au_flags = 0;
> > --
> > 1.8.3.1
> >
>
> --
> Chuck Lever
>
>
>
On Wed, Mar 25, 2020 at 5:55 PM Chuck Lever <[email protected]> wrote:
>
>
>
> > On Mar 25, 2020, at 5:52 PM, Trond Myklebust <[email protected]> wrote:
> >
> > On Wed, 2020-03-25 at 17:43 -0400, Chuck Lever wrote:
> >>> On Mar 25, 2020, at 5:33 PM, Trond Myklebust <
> >>> [email protected]> wrote:
> >>>
> >>> Hi Olga,
> >>>
> >>> On Wed, 2020-03-25 at 17:01 -0400, Olga Kornievskaia wrote:
> >>>> From: Olga Kornievskaia <[email protected]>
> >>>>
> >>>> Ever since commit 2c94b8eca1a2 ("SUNRPC: Use au_rslack when
> >>>> computing
> >>>> reply buffer size"). It changed how "req->rq_rcvsize" is
> >>>> calculated.
> >>>> It
> >>>> used to use au_cslack value which was nice and large and changed
> >>>> it
> >>>> to
> >>>> au_rslack value which turns out to be too small.
> >>>>
> >>>> Since 5.1, v3 mount with sec=krb5p fails against an Ontap server
> >>>> because client's receive buffer it too small.
> >>>>
> >>>> For gss krb5p, we need to account for the mic token in the
> >>>> verifier,
> >>>> and the wrap token in the wrap token.
> >>>>
> >>>> RFC 4121 defines:
> >>>> mic token
> >>>> Octet no Name Description
> >>>> ---------------------------------------------------------
> >>>> -
> >>>> ----
> >>>> 0..1 TOK_ID Identification field. Tokens emitted
> >>>> by
> >>>> GSS_GetMIC() contain the hex value 04
> >>>> 04
> >>>> expressed in big-endian order in this
> >>>> field.
> >>>> 2 Flags Attributes field, as described in
> >>>> section
> >>>> 4.2.2.
> >>>> 3..7 Filler Contains five octets of hex value FF.
> >>>> 8..15 SND_SEQ Sequence number field in clear text,
> >>>> expressed in big-endian order.
> >>>> 16..last SGN_CKSUM Checksum of the "to-be-signed" data
> >>>> and
> >>>> octet 0..15, as described in section
> >>>> 4.2.4.
> >>>>
> >>>> that's 16bytes (GSS_KRB5_TOK_HDR_LEN) + chksum
> >>>>
> >>>> wrap token
> >>>> Octet no Name Description
> >>>> ---------------------------------------------------------
> >>>> -
> >>>> ----
> >>>> 0..1 TOK_ID Identification field. Tokens emitted
> >>>> by
> >>>> GSS_Wrap() contain the hex value 05
> >>>> 04
> >>>> expressed in big-endian order in this
> >>>> field.
> >>>> 2 Flags Attributes field, as described in
> >>>> section
> >>>> 4.2.2.
> >>>> 3 Filler Contains the hex value FF.
> >>>> 4..5 EC Contains the "extra count" field, in
> >>>> big-
> >>>> endian order as described in section
> >>>> 4.2.3.
> >>>> 6..7 RRC Contains the "right rotation count"
> >>>> in
> >>>> big-
> >>>> endian order, as described in section
> >>>> 4.2.5.
> >>>> 8..15 SND_SEQ Sequence number field in clear text,
> >>>> expressed in big-endian order.
> >>>> 16..last Data Encrypted data for Wrap tokens with
> >>>> confidentiality, or plaintext data
> >>>> followed
> >>>> by the checksum for Wrap tokens
> >>>> without
> >>>> confidentiality, as described in
> >>>> section
> >>>> 4.2.4.
> >>>>
> >>>> Also 16bytes of header (GSS_KRB5_TOK_HDR_LEN), encrypted data,
> >>>> and
> >>>> cksum
> >>>> (other things like padding)
> >>>>
> >>>> RFC 3961 defines known cksum sizes:
> >>>> Checksum
> >>>> type sumtype checksum section or
> >>>> value size refe
> >>>> ren
> >>>> ce
> >>>> -------------------------------------------------------------
> >>>> ---
> >>>> -----
> >>>>
> >>>> CRC32 1 4 6.1.
> >>>> 3
> >>>> rsa-
> >>>> md4 2 16 6.1.2
> >>>> rsa-md4-
> >>>> des 3 24 6.2.5
> >>>> des-
> >>>> mac 4 16 6.2.7
> >>>> des-mac-
> >>>> k 5 8 6.2.8
> >>>> rsa-md4-des-
> >>>> k 6 16 6.2.6
> >>>> rsa-
> >>>> md5 7 16 6.1.1
> >>>> rsa-md5-
> >>>> des 8 24 6.2.4
> >>>> rsa-md5-
> >>>> des3 9 24 ??
> >>>> sha1
> >>>> (unkeyed) 10 20 ??
> >>>> hmac-sha1-des3-
> >>>> kd 12 20 6.3
> >>>> hmac-sha1-
> >>>> des3 13 20 ??
> >>>> sha1
> >>>> (unkeyed) 14 20 ??
> >>>> hmac-sha1-96-
> >>>> aes128 15 20 [KRB5-
> >>>> AES]
> >>>> hmac-sha1-96-
> >>>> aes256 16 20 [KRB5-
> >>>> AES]
> >>>>
> >>>> [reserved] 0x8003 ? [GSS-
> >>>> KRB5]
> >>>>
> >>>> Linux kernel now mainly supports type 15,16 so max cksum size is
> >>>> 20bytes.
> >>>> (GSS_KRB5_MAX_CKSUM_LEN)
> >>>>
> >>>> Re-use already existing define of GSS_KRB5_MAX_SLACK_NEEDED
> >>>> that's
> >>>> used
> >>>> for encoding the gss_wrap tokens (same tokens are used in reply).
> >>>>
> >>>> Fixes: 2c94b8eca1a2 ("SUNRPC: Use au_rslack when computing reply
> >>>> buffer size")
> >>>> Signed-off-by: Olga Kornievskaia <[email protected]>
> >>>> ---
> >>>> net/sunrpc/auth_gss/auth_gss.c | 5 ++++-
> >>>> 1 file changed, 4 insertions(+), 1 deletion(-)
> >>>>
> >>>> diff --git a/net/sunrpc/auth_gss/auth_gss.c
> >>>> b/net/sunrpc/auth_gss/auth_gss.c
> >>>> index 24ca861..5a733a6 100644
> >>>> --- a/net/sunrpc/auth_gss/auth_gss.c
> >>>> +++ b/net/sunrpc/auth_gss/auth_gss.c
> >>>> @@ -20,6 +20,7 @@
> >>>> #include <linux/sunrpc/clnt.h>
> >>>> #include <linux/sunrpc/auth.h>
> >>>> #include <linux/sunrpc/auth_gss.h>
> >>>> +#include <linux/sunrpc/gss_krb5.h>
> >>>> #include <linux/sunrpc/svcauth_gss.h>
> >>>> #include <linux/sunrpc/gss_err.h>
> >>>> #include <linux/workqueue.h>
> >>>> @@ -51,6 +52,8 @@
> >>>> /* length of a krb5 verifier (48), plus data added before
> >>>> arguments
> >>>> when
> >>>> * using integrity (two 4-byte integers): */
> >>>> #define GSS_VERF_SLACK 100
> >>>> +/* covers lengths of gss_unwrap() extra kerberos mic and wrap
> >>>> token
> >>>> */
> >>>> +#define GSS_RESP_SLACK (GSS_KRB5_MAX_SLACK_NEEDED <<
> >>>> 2)
> >>>>
> >>>> static DEFINE_HASHTABLE(gss_auth_hash_table, 4);
> >>>> static DEFINE_SPINLOCK(gss_auth_hash_lock);
> >>>> @@ -1050,7 +1053,7 @@ static void gss_pipe_free(struct gss_pipe
> >>>> *p)
> >>>> goto err_put_mech;
> >>>> auth = &gss_auth->rpc_auth;
> >>>> auth->au_cslack = GSS_CRED_SLACK >> 2;
> >>>> - auth->au_rslack = GSS_VERF_SLACK >> 2;
> >>>> + auth->au_rslack = GSS_RESP_SLACK >> 2;
> >>>> auth->au_verfsize = GSS_VERF_SLACK >> 2;
> >>>> auth->au_ralign = GSS_VERF_SLACK >> 2;
> >>>> auth->au_flags = 0;
> >>>
> >>> Is this a sufficient fix, though? It looks to me as if the above is
> >>> just an initial value that gets adjusted on the fly in
> >>> gss_unwrap_resp_priv():
> >>>
> >>> auth->au_rslack = auth->au_verfsize + 2 +
> >>> XDR_QUADLEN(savedlen - rcv_buf->len);
> >>> auth->au_ralign = auth->au_verfsize + 2 +
> >>> XDR_QUADLEN(savedlen - rcv_buf->len);
> >>
> >> That's correct. The GSS_*_SLACK value is a _sz value that is
> >> the largest possible expected size of the extra GSS data.
> >>
> >>
> >>> My questions would be
> >>>
> >>> - Are we sure that the above calculation (in
> >>> gss_unwrap_resp_priv()) is
> >>> correct?
> >>
> >> Yes, this is the correct computation.
> >>
> >> We know this because if the initial au_rslack value is large
> >> enough, then subsequent Replies have the correct amount of buffer
> >> space and always succeed.
> >>
> >>
> >>> - Are we sure that the above calculation always gives the same
> >>> answer
> >>> over time? We probably should not store a value that keeps
> >>> changing.
> >>
> >> It does not change after the first Reply. au_rslack is typically
> >> adjusted downwards from the initial value based on the size of the
> >> first received Reply.
> >>
> >> Not setting these variables after the first Reply has been received
> >> would be a minor optimization that could be done after Olga's fix.
> >>
> >
> > OK. So you're both saying that as long as the initial value is correct,
> > we're good for the duration of the GSS session? Fair enough, I'll apply
> > this patch for 5.7 then.
>
> Thanks, please see my one-line correction. I think the definition of
> GSS_RESP_SLACK should not include the "<< 2", I would like Olga to
> confirm.
Yes I do.
> > Let's also fix up the above in a separate patch to not keep setting
> > auth->au_rslack / auth->au_ralign if their values are not changing.
> > That should prevent unnecessary cache line bouncing.
>
> I volunteer, unless Olga wants to take it.
Please do the fix (as because I'm not understanding what needs to be
fixed and I'd be bugging you folks to explain it first).
>
>
> --
> Chuck Lever
>
>
>
> On Mar 26, 2020, at 8:04 AM, Olga Kornievskaia <[email protected]> wrote:
>
> On Wed, Mar 25, 2020 at 5:34 PM Chuck Lever <[email protected]> wrote:
>>
>>
>>
>>> On Mar 25, 2020, at 5:01 PM, Olga Kornievskaia <[email protected]> wrote:
>>>
>>> From: Olga Kornievskaia <[email protected]>
>>>
>>> Ever since commit 2c94b8eca1a2 ("SUNRPC: Use au_rslack when computing
>>> reply buffer size"). It changed how "req->rq_rcvsize" is calculated. It
>>> used to use au_cslack value which was nice and large and changed it to
>>> au_rslack value which turns out to be too small.
>>>
>>> Since 5.1, v3 mount with sec=krb5p fails against an Ontap server
>>> because client's receive buffer it too small.
>>>
>>> For gss krb5p, we need to account for the mic token in the verifier,
>>> and the wrap token in the wrap token.
>>>
>>> RFC 4121 defines:
>>> mic token
>>> Octet no Name Description
>>> --------------------------------------------------------------
>>> 0..1 TOK_ID Identification field. Tokens emitted by
>>> GSS_GetMIC() contain the hex value 04 04
>>> expressed in big-endian order in this
>>> field.
>>> 2 Flags Attributes field, as described in section
>>> 4.2.2.
>>> 3..7 Filler Contains five octets of hex value FF.
>>> 8..15 SND_SEQ Sequence number field in clear text,
>>> expressed in big-endian order.
>>> 16..last SGN_CKSUM Checksum of the "to-be-signed" data and
>>> octet 0..15, as described in section 4.2.4.
>>>
>>> that's 16bytes (GSS_KRB5_TOK_HDR_LEN) + chksum
>>>
>>> wrap token
>>> Octet no Name Description
>>> --------------------------------------------------------------
>>> 0..1 TOK_ID Identification field. Tokens emitted by
>>> GSS_Wrap() contain the hex value 05 04
>>> expressed in big-endian order in this
>>> field.
>>> 2 Flags Attributes field, as described in section
>>> 4.2.2.
>>> 3 Filler Contains the hex value FF.
>>> 4..5 EC Contains the "extra count" field, in big-
>>> endian order as described in section 4.2.3.
>>> 6..7 RRC Contains the "right rotation count" in big-
>>> endian order, as described in section
>>> 4.2.5.
>>> 8..15 SND_SEQ Sequence number field in clear text,
>>> expressed in big-endian order.
>>> 16..last Data Encrypted data for Wrap tokens with
>>> confidentiality, or plaintext data followed
>>> by the checksum for Wrap tokens without
>>> confidentiality, as described in section
>>> 4.2.4.
>>>
>>> Also 16bytes of header (GSS_KRB5_TOK_HDR_LEN), encrypted data, and cksum
>>> (other things like padding)
>>>
>>> RFC 3961 defines known cksum sizes:
>>> Checksum type sumtype checksum section or
>>> value size reference
>>> ---------------------------------------------------------------------
>>> CRC32 1 4 6.1.3
>>> rsa-md4 2 16 6.1.2
>>> rsa-md4-des 3 24 6.2.5
>>> des-mac 4 16 6.2.7
>>> des-mac-k 5 8 6.2.8
>>> rsa-md4-des-k 6 16 6.2.6
>>> rsa-md5 7 16 6.1.1
>>> rsa-md5-des 8 24 6.2.4
>>> rsa-md5-des3 9 24 ??
>>> sha1 (unkeyed) 10 20 ??
>>> hmac-sha1-des3-kd 12 20 6.3
>>> hmac-sha1-des3 13 20 ??
>>> sha1 (unkeyed) 14 20 ??
>>> hmac-sha1-96-aes128 15 20 [KRB5-AES]
>>> hmac-sha1-96-aes256 16 20 [KRB5-AES]
>>> [reserved] 0x8003 ? [GSS-KRB5]
>>>
>>> Linux kernel now mainly supports type 15,16 so max cksum size is 20bytes.
>>> (GSS_KRB5_MAX_CKSUM_LEN)
>>>
>>> Re-use already existing define of GSS_KRB5_MAX_SLACK_NEEDED that's used
>>> for encoding the gss_wrap tokens (same tokens are used in reply).
>>>
>>> Fixes: 2c94b8eca1a2 ("SUNRPC: Use au_rslack when computing reply buffer size")
>>> Signed-off-by: Olga Kornievskaia <[email protected]>
>>> ---
>>> net/sunrpc/auth_gss/auth_gss.c | 5 ++++-
>>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
>>> index 24ca861..5a733a6 100644
>>> --- a/net/sunrpc/auth_gss/auth_gss.c
>>> +++ b/net/sunrpc/auth_gss/auth_gss.c
>>> @@ -20,6 +20,7 @@
>>> #include <linux/sunrpc/clnt.h>
>>> #include <linux/sunrpc/auth.h>
>>> #include <linux/sunrpc/auth_gss.h>
>>> +#include <linux/sunrpc/gss_krb5.h>
>>> #include <linux/sunrpc/svcauth_gss.h>
>>> #include <linux/sunrpc/gss_err.h>
>>> #include <linux/workqueue.h>
>>> @@ -51,6 +52,8 @@
>>> /* length of a krb5 verifier (48), plus data added before arguments when
>>> * using integrity (two 4-byte integers): */
>>> #define GSS_VERF_SLACK 100
>>> +/* covers lengths of gss_unwrap() extra kerberos mic and wrap token */
>>> +#define GSS_RESP_SLACK (GSS_KRB5_MAX_SLACK_NEEDED << 2)
>>
>> GSS_KRB5_MAX_SLACK_NEEDED is already in bytes. Shouldn't need the "<< 2" here.
>
>
> Ok yes just for my own understanding I convinced myself that indeed
> "<<2" is not needed here because clnt.c will do rq_rcvsize is <<=2.
>
> Now question: Do I even need to introduce GSS_RES_SLACK at all or
> perhaps just use GSS_KRB5_MAX_SLACK_NEEDED to initialize?
For the moment, Kerberos is the only supported security flavor,
so we're using that value without any other modification. I guess
the extra "#define GSS_RESP_SLACK" seems pointless in that case.
I'm OK with using the KRB5_MAX_SLACK macro directly if there's no
objection from others.
>>> static DEFINE_HASHTABLE(gss_auth_hash_table, 4);
>>> static DEFINE_SPINLOCK(gss_auth_hash_lock);
>>> @@ -1050,7 +1053,7 @@ static void gss_pipe_free(struct gss_pipe *p)
>>> goto err_put_mech;
>>> auth = &gss_auth->rpc_auth;
>>> auth->au_cslack = GSS_CRED_SLACK >> 2;
>>> - auth->au_rslack = GSS_VERF_SLACK >> 2;
>>> + auth->au_rslack = GSS_RESP_SLACK >> 2;
>>> auth->au_verfsize = GSS_VERF_SLACK >> 2;
>>> auth->au_ralign = GSS_VERF_SLACK >> 2;
>>> auth->au_flags = 0;
>>> --
>>> 1.8.3.1
>>>
>>
>> --
>> Chuck Lever
--
Chuck Lever