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Date:	Wed, 13 Apr 2016 00:07:28 -0500
From:	Shirish Pargaonkar <shirishpargaonkar@...il.com>
To:	Al Viro <viro@...iv.linux.org.uk>
Cc:	linux-cifs <linux-cifs@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/6] cifs: merge the hash calculation helpers

Looks correct.
Tested with -o vers=1.0, -o vers=2.0, and -o vers=2.1.
Will test using mount option vers=3.0 as soon as I find a server.

Reviewed-by: Shirish Pargaonkar <shirishpargaonkar@...il.com>
Tested-by: Shirish Pargaonkar <shirishpargaonkar@...il.com>

On Sat, Apr 9, 2016 at 3:50 PM, Al Viro <viro@...iv.linux.org.uk> wrote:
> three practically identical copies...
>
> Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
> ---
>  fs/cifs/cifsencrypt.c   |  97 ++++++++++++++++++++++++-------------------
>  fs/cifs/cifsproto.h     |   3 ++
>  fs/cifs/smb2transport.c | 107 +++++-------------------------------------------
>  3 files changed, 67 insertions(+), 140 deletions(-)
>
> diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
> index 4897dac..6aeb8d4 100644
> --- a/fs/cifs/cifsencrypt.c
> +++ b/fs/cifs/cifsencrypt.c
> @@ -66,45 +66,15 @@ cifs_crypto_shash_md5_allocate(struct TCP_Server_Info *server)
>         return 0;
>  }
>
> -/*
> - * Calculate and return the CIFS signature based on the mac key and SMB PDU.
> - * The 16 byte signature must be allocated by the caller. Note we only use the
> - * 1st eight bytes and that the smb header signature field on input contains
> - * the sequence number before this function is called. Also, this function
> - * should be called with the server->srv_mutex held.
> - */
> -static int cifs_calc_signature(struct smb_rqst *rqst,
> -                       struct TCP_Server_Info *server, char *signature)
> +int __cifs_calc_signature(struct smb_rqst *rqst,
> +                       struct TCP_Server_Info *server, char *signature,
> +                       struct shash_desc *shash)
>  {
>         int i;
>         int rc;
>         struct kvec *iov = rqst->rq_iov;
>         int n_vec = rqst->rq_nvec;
>
> -       if (iov == NULL || signature == NULL || server == NULL)
> -               return -EINVAL;
> -
> -       if (!server->secmech.sdescmd5) {
> -               rc = cifs_crypto_shash_md5_allocate(server);
> -               if (rc) {
> -                       cifs_dbg(VFS, "%s: Can't alloc md5 crypto\n", __func__);
> -                       return -1;
> -               }
> -       }
> -
> -       rc = crypto_shash_init(&server->secmech.sdescmd5->shash);
> -       if (rc) {
> -               cifs_dbg(VFS, "%s: Could not init md5\n", __func__);
> -               return rc;
> -       }
> -
> -       rc = crypto_shash_update(&server->secmech.sdescmd5->shash,
> -               server->session_key.response, server->session_key.len);
> -       if (rc) {
> -               cifs_dbg(VFS, "%s: Could not update with response\n", __func__);
> -               return rc;
> -       }
> -
>         for (i = 0; i < n_vec; i++) {
>                 if (iov[i].iov_len == 0)
>                         continue;
> @@ -117,12 +87,10 @@ static int cifs_calc_signature(struct smb_rqst *rqst,
>                 if (i == 0) {
>                         if (iov[0].iov_len <= 8) /* cmd field at offset 9 */
>                                 break; /* nothing to sign or corrupt header */
> -                       rc =
> -                       crypto_shash_update(&server->secmech.sdescmd5->shash,
> +                       rc = crypto_shash_update(shash,
>                                 iov[i].iov_base + 4, iov[i].iov_len - 4);
>                 } else {
> -                       rc =
> -                       crypto_shash_update(&server->secmech.sdescmd5->shash,
> +                       rc = crypto_shash_update(shash,
>                                 iov[i].iov_base, iov[i].iov_len);
>                 }
>                 if (rc) {
> @@ -134,21 +102,64 @@ static int cifs_calc_signature(struct smb_rqst *rqst,
>
>         /* now hash over the rq_pages array */
>         for (i = 0; i < rqst->rq_npages; i++) {
> -               struct kvec p_iov;
> +               void *kaddr = kmap(rqst->rq_pages[i]);
> +               size_t len = rqst->rq_pagesz;
> +
> +               if (i == rqst->rq_npages - 1)
> +                       len = rqst->rq_tailsz;
> +
> +               crypto_shash_update(shash, kaddr, len);
>
> -               cifs_rqst_page_to_kvec(rqst, i, &p_iov);
> -               crypto_shash_update(&server->secmech.sdescmd5->shash,
> -                                       p_iov.iov_base, p_iov.iov_len);
>                 kunmap(rqst->rq_pages[i]);
>         }
>
> -       rc = crypto_shash_final(&server->secmech.sdescmd5->shash, signature);
> +       rc = crypto_shash_final(shash, signature);
>         if (rc)
> -               cifs_dbg(VFS, "%s: Could not generate md5 hash\n", __func__);
> +               cifs_dbg(VFS, "%s: Could not generate hash\n", __func__);
>
>         return rc;
>  }
>
> +/*
> + * Calculate and return the CIFS signature based on the mac key and SMB PDU.
> + * The 16 byte signature must be allocated by the caller. Note we only use the
> + * 1st eight bytes and that the smb header signature field on input contains
> + * the sequence number before this function is called. Also, this function
> + * should be called with the server->srv_mutex held.
> + */
> +static int cifs_calc_signature(struct smb_rqst *rqst,
> +                       struct TCP_Server_Info *server, char *signature)
> +{
> +       int rc;
> +
> +       if (!rqst->rq_iov || !signature || !server)
> +               return -EINVAL;
> +
> +       if (!server->secmech.sdescmd5) {
> +               rc = cifs_crypto_shash_md5_allocate(server);
> +               if (rc) {
> +                       cifs_dbg(VFS, "%s: Can't alloc md5 crypto\n", __func__);
> +                       return -1;
> +               }
> +       }
> +
> +       rc = crypto_shash_init(&server->secmech.sdescmd5->shash);
> +       if (rc) {
> +               cifs_dbg(VFS, "%s: Could not init md5\n", __func__);
> +               return rc;
> +       }
> +
> +       rc = crypto_shash_update(&server->secmech.sdescmd5->shash,
> +               server->session_key.response, server->session_key.len);
> +       if (rc) {
> +               cifs_dbg(VFS, "%s: Could not update with response\n", __func__);
> +               return rc;
> +       }
> +
> +       return __cifs_calc_signature(rqst, server, signature,
> +                                    &server->secmech.sdescmd5->shash);
> +}
> +
>  /* must be called with server->srv_mutex held */
>  int cifs_sign_rqst(struct smb_rqst *rqst, struct TCP_Server_Info *server,
>                    __u32 *pexpected_response_sequence_number)
> diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
> index eed7ff5..d9b4f44 100644
> --- a/fs/cifs/cifsproto.h
> +++ b/fs/cifs/cifsproto.h
> @@ -512,4 +512,7 @@ int cifs_create_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
>                            struct cifs_sb_info *cifs_sb,
>                            const unsigned char *path, char *pbuf,
>                            unsigned int *pbytes_written);
> +int __cifs_calc_signature(struct smb_rqst *rqst,
> +                       struct TCP_Server_Info *server, char *signature,
> +                       struct shash_desc *shash);
>  #endif                 /* _CIFSPROTO_H */
> diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c
> index 8732a43..bc9a7b6 100644
> --- a/fs/cifs/smb2transport.c
> +++ b/fs/cifs/smb2transport.c
> @@ -135,11 +135,10 @@ smb2_find_smb_ses(struct smb2_hdr *smb2hdr, struct TCP_Server_Info *server)
>  int
>  smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
>  {
> -       int i, rc;
> +       int rc;
>         unsigned char smb2_signature[SMB2_HMACSHA256_SIZE];
>         unsigned char *sigptr = smb2_signature;
>         struct kvec *iov = rqst->rq_iov;
> -       int n_vec = rqst->rq_nvec;
>         struct smb2_hdr *smb2_pdu = (struct smb2_hdr *)iov[0].iov_base;
>         struct cifs_ses *ses;
>
> @@ -171,53 +170,11 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
>                 return rc;
>         }
>
> -       for (i = 0; i < n_vec; i++) {
> -               if (iov[i].iov_len == 0)
> -                       continue;
> -               if (iov[i].iov_base == NULL) {
> -                       cifs_dbg(VFS, "null iovec entry\n");
> -                       return -EIO;
> -               }
> -               /*
> -                * The first entry includes a length field (which does not get
> -                * signed that occupies the first 4 bytes before the header).
> -                */
> -               if (i == 0) {
> -                       if (iov[0].iov_len <= 8) /* cmd field at offset 9 */
> -                               break; /* nothing to sign or corrupt header */
> -                       rc =
> -                       crypto_shash_update(
> -                               &server->secmech.sdeschmacsha256->shash,
> -                               iov[i].iov_base + 4, iov[i].iov_len - 4);
> -               } else {
> -                       rc =
> -                       crypto_shash_update(
> -                               &server->secmech.sdeschmacsha256->shash,
> -                               iov[i].iov_base, iov[i].iov_len);
> -               }
> -               if (rc) {
> -                       cifs_dbg(VFS, "%s: Could not update with payload\n",
> -                                __func__);
> -                       return rc;
> -               }
> -       }
> -
> -       /* now hash over the rq_pages array */
> -       for (i = 0; i < rqst->rq_npages; i++) {
> -               struct kvec p_iov;
> -
> -               cifs_rqst_page_to_kvec(rqst, i, &p_iov);
> -               crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
> -                                       p_iov.iov_base, p_iov.iov_len);
> -               kunmap(rqst->rq_pages[i]);
> -       }
> -
> -       rc = crypto_shash_final(&server->secmech.sdeschmacsha256->shash,
> -                               sigptr);
> -       if (rc)
> -               cifs_dbg(VFS, "%s: Could not generate sha256 hash\n", __func__);
> +       rc = __cifs_calc_signature(rqst, server, sigptr,
> +               &server->secmech.sdeschmacsha256->shash);
>
> -       memcpy(smb2_pdu->Signature, sigptr, SMB2_SIGNATURE_SIZE);
> +       if (!rc)
> +               memcpy(smb2_pdu->Signature, sigptr, SMB2_SIGNATURE_SIZE);
>
>         return rc;
>  }
> @@ -395,12 +352,10 @@ generate_smb311signingkey(struct cifs_ses *ses)
>  int
>  smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
>  {
> -       int i;
>         int rc = 0;
>         unsigned char smb3_signature[SMB2_CMACAES_SIZE];
>         unsigned char *sigptr = smb3_signature;
>         struct kvec *iov = rqst->rq_iov;
> -       int n_vec = rqst->rq_nvec;
>         struct smb2_hdr *smb2_pdu = (struct smb2_hdr *)iov[0].iov_base;
>         struct cifs_ses *ses;
>
> @@ -431,54 +386,12 @@ smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
>                 cifs_dbg(VFS, "%s: Could not init cmac aes\n", __func__);
>                 return rc;
>         }
> +
> +       rc = __cifs_calc_signature(rqst, server, sigptr,
> +                                  &server->secmech.sdesccmacaes->shash);
>
> -       for (i = 0; i < n_vec; i++) {
> -               if (iov[i].iov_len == 0)
> -                       continue;
> -               if (iov[i].iov_base == NULL) {
> -                       cifs_dbg(VFS, "null iovec entry");
> -                       return -EIO;
> -               }
> -               /*
> -                * The first entry includes a length field (which does not get
> -                * signed that occupies the first 4 bytes before the header).
> -                */
> -               if (i == 0) {
> -                       if (iov[0].iov_len <= 8) /* cmd field at offset 9 */
> -                               break; /* nothing to sign or corrupt header */
> -                       rc =
> -                       crypto_shash_update(
> -                               &server->secmech.sdesccmacaes->shash,
> -                               iov[i].iov_base + 4, iov[i].iov_len - 4);
> -               } else {
> -                       rc =
> -                       crypto_shash_update(
> -                               &server->secmech.sdesccmacaes->shash,
> -                               iov[i].iov_base, iov[i].iov_len);
> -               }
> -               if (rc) {
> -                       cifs_dbg(VFS, "%s: Couldn't update cmac aes with payload\n",
> -                                                       __func__);
> -                       return rc;
> -               }
> -       }
> -
> -       /* now hash over the rq_pages array */
> -       for (i = 0; i < rqst->rq_npages; i++) {
> -               struct kvec p_iov;
> -
> -               cifs_rqst_page_to_kvec(rqst, i, &p_iov);
> -               crypto_shash_update(&server->secmech.sdesccmacaes->shash,
> -                                       p_iov.iov_base, p_iov.iov_len);
> -               kunmap(rqst->rq_pages[i]);
> -       }
> -
> -       rc = crypto_shash_final(&server->secmech.sdesccmacaes->shash,
> -                                               sigptr);
> -       if (rc)
> -               cifs_dbg(VFS, "%s: Could not generate cmac aes\n", __func__);
> -
> -       memcpy(smb2_pdu->Signature, sigptr, SMB2_SIGNATURE_SIZE);
> +       if (!rc)
> +               memcpy(smb2_pdu->Signature, sigptr, SMB2_SIGNATURE_SIZE);
>
>         return rc;
>  }
> --
> 2.8.0.rc3
>
> --
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