2018-02-16 10:19 GMT-08:00 Aurelien Aptel <aaptel@xxxxxxxx>:
> SMB3.11 clients must implement pre-authentification integrity.
>
> * new mechanism to certify requests/responses happening before Tree
> Connect.
> * supersedes VALIDATE_NEGOTIATE
> * fixes signing for SMB3.11
>
> Signed-off-by: Aurelien Aptel <aaptel@xxxxxxxx>
> ---
> fs/cifs/cifsglob.h | 5 +++--
> fs/cifs/smb2misc.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> fs/cifs/smb2pdu.c | 25 +++++++++++++++++++++
> fs/cifs/smb2pdu.h | 1 +
> fs/cifs/smb2proto.h | 2 ++
> fs/cifs/transport.c | 17 ++++++++++++++
> 6 files changed, 112 insertions(+), 2 deletions(-)
>
> diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
> index 765fc2c9fd91..c294093f04d5 100644
> --- a/fs/cifs/cifsglob.h
> +++ b/fs/cifs/cifsglob.h
> @@ -675,7 +675,8 @@ struct TCP_Server_Info {
> unsigned int max_read;
> unsigned int max_write;
> #ifdef CONFIG_CIFS_SMB311
> - __u8 preauth_sha_hash[64]; /* save initital negprot hash */
> + /* save initital negprot hash */
> + __u8 preauth_sha_hash[SMB2_PREAUTH_HASH_SIZE];
> #endif /* 3.1.1 */
> struct delayed_work reconnect; /* reconnect workqueue job */
> struct mutex reconnect_mutex; /* prevent simultaneous reconnects */
> @@ -864,7 +865,7 @@ struct cifs_ses {
> __u8 smb3encryptionkey[SMB3_SIGN_KEY_SIZE];
> __u8 smb3decryptionkey[SMB3_SIGN_KEY_SIZE];
> #ifdef CONFIG_CIFS_SMB311
> - __u8 preauth_sha_hash[64];
> + __u8 preauth_sha_hash[SMB2_PREAUTH_HASH_SIZE];
> #endif /* 3.1.1 */
> };
>
> diff --git a/fs/cifs/smb2misc.c b/fs/cifs/smb2misc.c
> index 76d03abaa38c..da012c3ab700 100644
> --- a/fs/cifs/smb2misc.c
> +++ b/fs/cifs/smb2misc.c
> @@ -706,3 +706,67 @@ smb2_handle_cancelled_mid(char *buffer, struct TCP_Server_Info *server)
>
> return 0;
> }
> +
> +#ifdef CONFIG_CIFS_SMB311
> +/**
> + * smb311_update_preauth_hash - update @ses hash with the packet data in @iov
> + *
> + * Assumes @iov does not contain the rfc1002 length and iov[0] has the
> + * SMB2 header.
> + */
> +int
> +smb311_update_preauth_hash(struct cifs_ses *ses, struct kvec *iov, int nvec)
> +{
> + int i, rc;
> + struct sdesc *d;
> + struct smb2_sync_hdr *hdr;
> +
> + if (ses->server->tcpStatus == CifsGood) {
> + /* skip non smb311 connections */
> + if (ses->server->dialect != SMB311_PROT_ID)
> + return 0;
> +
> + /* skip last sess setup response */
Do we skip only last sess setup response or every response with SIGNED flag? In the latter case the comment should reflect it.
> + hdr = (struct smb2_sync_hdr *)iov[0].iov_base;
> + if (hdr->Flags & SMB2_FLAGS_SIGNED)
> + return 0;
> + }
> +
> + rc = smb311_crypto_shash_allocate(ses->server);
> + if (rc)
> + return rc;
> +
> + d = ses->server->secmech.sdescsha512;
> + rc = crypto_shash_init(&d->shash);
> + if (rc) {
> + cifs_dbg(VFS, "%s: could not init sha512 shash\n", __func__);
> + return rc;
> + }
> +
> + rc = crypto_shash_update(&d->shash, ses->preauth_sha_hash,
> + SMB2_PREAUTH_HASH_SIZE);
> + if (rc) {
> + cifs_dbg(VFS, "%s: could not update sha512 shash\n", __func__);
> + return rc;
> + }
> +
> + for (i = 0; i < nvec; i++) {
> + rc = crypto_shash_update(&d->shash,
> + iov[i].iov_base, iov[i].iov_len);
> + if (rc) {
> + cifs_dbg(VFS, "%s: could not update sha512 shash\n",
> + __func__);
> + return rc;
> + }
> + }
> +
> + rc = crypto_shash_final(&d->shash, ses->preauth_sha_hash);
> + if (rc) {
> + cifs_dbg(VFS, "%s: could not finalize sha512 shash\n",
> + __func__);
> + return rc;
> + }
> +
> + return 0;
> +}
> +#endif
> diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
> index ab4c20687cc0..4b6920de2541 100644
> --- a/fs/cifs/smb2pdu.c
> +++ b/fs/cifs/smb2pdu.c
> @@ -453,6 +453,10 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
> return rc;
>
> req->sync_hdr.SessionId = 0;
> +#ifdef CONFIG_CIFS_SMB311
> + memset(server->preauth_sha_hash, 0, SMB2_PREAUTH_HASH_SIZE);
> + memset(ses->preauth_sha_hash, 0, SMB2_PREAUTH_HASH_SIZE);
> +#endif
>
> if (strcmp(ses->server->vals->version_string,
> SMB3ANY_VERSION_STRING) == 0) {
> @@ -564,6 +568,15 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
>
> /* BB: add check that dialect was valid given dialect(s) we asked for */
>
> +#ifdef CONFIG_CIFS_SMB311
> + /*
> + * Keep a copy of the hash after negprot. This hash will be
> + * the starting hash value for all sessions made from this
> + * server.
> + */
> + memcpy(server->preauth_sha_hash, ses->preauth_sha_hash,
> + SMB2_PREAUTH_HASH_SIZE);
> +#endif
> /* SMB2 only has an extended negflavor */
> server->negflavor = CIFS_NEGFLAVOR_EXTENDED;
> /* set it to the maximum buffer size value we can send with 1 credit */
> @@ -621,6 +634,10 @@ int smb3_validate_negotiate(const unsigned int xid, struct cifs_tcon *tcon)
> return 0;
> #endif
>
> + /* In SMB3.11 preauth integrity supersedes validate negotiate */
> + if (tcon->ses->server->dialect == SMB311_PROT_ID)
> + return 0;
> +
> /*
> * validation ioctl must be signed, so no point sending this if we
> * can not sign it (ie are not known user). Even if signing is not
> @@ -1148,6 +1165,14 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
> sess_data->buf0_type = CIFS_NO_BUFFER;
> sess_data->nls_cp = (struct nls_table *) nls_cp;
>
> +#ifdef CONFIG_CIFS_SMB311
> + /*
> + * Initialize the session hash with the server one.
> + */
> + memcpy(ses->preauth_sha_hash, ses->server->preauth_sha_hash,
> + SMB2_PREAUTH_HASH_SIZE);
> +#endif
> +
> while (sess_data->func)
> sess_data->func(sess_data);
>
> diff --git a/fs/cifs/smb2pdu.h b/fs/cifs/smb2pdu.h
> index 2a2b34ccaf49..8b901c69a65a 100644
> --- a/fs/cifs/smb2pdu.h
> +++ b/fs/cifs/smb2pdu.h
> @@ -264,6 +264,7 @@ struct smb2_negotiate_req {
> #define SMB311_SALT_SIZE 32
> /* Hash Algorithm Types */
> #define SMB2_PREAUTH_INTEGRITY_SHA512 cpu_to_le16(0x0001)
> +#define SMB2_PREAUTH_HASH_SIZE 64
>
> struct smb2_preauth_neg_context {
> __le16 ContextType; /* 1 */
> diff --git a/fs/cifs/smb2proto.h b/fs/cifs/smb2proto.h
> index 3b8e9c2e55bc..cbcce3f7e86f 100644
> --- a/fs/cifs/smb2proto.h
> +++ b/fs/cifs/smb2proto.h
> @@ -204,5 +204,7 @@ extern enum securityEnum smb2_select_sectype(struct TCP_Server_Info *,
> enum securityEnum);
> #ifdef CONFIG_CIFS_SMB311
> extern int smb311_crypto_shash_allocate(struct TCP_Server_Info *server);
> +extern int smb311_update_preauth_hash(struct cifs_ses *ses,
> + struct kvec *iov, int nvec);
> #endif
> #endif /* _SMB2PROTO_H */
> diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
> index 9779b3292d8e..665661464067 100644
> --- a/fs/cifs/transport.c
> +++ b/fs/cifs/transport.c
> @@ -37,6 +37,7 @@
> #include "cifsglob.h"
> #include "cifsproto.h"
> #include "cifs_debug.h"
> +#include "smb2proto.h"
> #include "smbdirect.h"
>
> /* Max number of iovectors we can use off the stack when sending requests. */
> @@ -751,6 +752,12 @@ cifs_send_recv(const unsigned int xid, struct cifs_ses *ses,
> if (rc < 0)
> goto out;
>
> +#ifdef CONFIG_CIFS_SMB311
> + if (ses->status == CifsNew)
> + smb311_update_preauth_hash(ses, rqst->rq_iov+1,
> + rqst->rq_nvec-1);
> +#endif
Is there a race here? Can it be a situation where ses->server->secmech.sdescsha512 is being updated by multiple threads calling cifs_send_recv()? E.g. we are trying to establish two smb connections over the same TCP connection in the same time. It seems that ses->server->secmech.sdescsha512 may be corrupted which will result in signing errors.
> +
> if (timeout == CIFS_ASYNC_OP)
> goto out;
>
> @@ -789,6 +796,16 @@ cifs_send_recv(const unsigned int xid, struct cifs_ses *ses,
> else
> *resp_buf_type = CIFS_SMALL_BUFFER;
>
> +#ifdef CONFIG_CIFS_SMB311
> + if (ses->status == CifsNew) {
> + struct kvec iov = {
> + .iov_base = buf + 4,
> + .iov_len = get_rfc1002_length(buf)
> + };
> + smb311_update_preauth_hash(ses, &iov, 1);
> + }
> +#endif
The same as above.
> +
> credits = ses->server->ops->get_credits(midQ);
>
> rc = ses->server->ops->check_receive(midQ, ses->server,
> --
> 2.12.3
>
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--
Best regards,
Pavel Shilovskiy
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