Messages in this thread | | | Subject | Re: [Patch v3 2/6] cifs: Allocate validate negotiation request through kmalloc | From | Tom Talpey <> | Date | Wed, 18 Apr 2018 07:32:28 -0400 |
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Two comments.
On 4/17/2018 8:33 PM, Long Li wrote: > From: Long Li <longli@microsoft.com> > > The data buffer allocated on the stack can't be DMA'ed, and hence can't send > through RDMA via SMB Direct.
This comment is confusing. Any registered memory can be DMA'd, need to state the reason for the choice here more clearly.
> > Fix this by allocating the request on the heap in smb3_validate_negotiate. > > Changes in v2: > Removed duplicated code on freeing buffers on function exit. > (Thanks to Parav Pandit <parav@mellanox.com>) > Fixed typo in the patch title. > > Changes in v3: > Added "Fixes" to the patch. > Changed sizeof() to use *pointer in place of struct. > > Fixes: ff1c038addc4 ("Check SMB3 dialects against downgrade attacks") > Signed-off-by: Long Li <longli@microsoft.com> > Cc: stable@vger.kernel.org > --- > fs/cifs/smb2pdu.c | 59 ++++++++++++++++++++++++++++++------------------------- > 1 file changed, 32 insertions(+), 27 deletions(-) > > diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c > index 0f044c4..5582a02 100644 > --- a/fs/cifs/smb2pdu.c > +++ b/fs/cifs/smb2pdu.c > @@ -729,8 +729,8 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses) > > int smb3_validate_negotiate(const unsigned int xid, struct cifs_tcon *tcon) > { > - int rc = 0; > - struct validate_negotiate_info_req vneg_inbuf; > + int ret, rc = -EIO; > + struct validate_negotiate_info_req *pneg_inbuf; > struct validate_negotiate_info_rsp *pneg_rsp = NULL; > u32 rsplen; > u32 inbuflen; /* max of 4 dialects */ > @@ -741,6 +741,9 @@ int smb3_validate_negotiate(const unsigned int xid, struct cifs_tcon *tcon) > if (tcon->ses->server->rdma) > return 0; > #endif > + pneg_inbuf = kmalloc(sizeof(*pneg_inbuf), GFP_KERNEL); > + if (!pneg_inbuf) > + return -ENOMEM;
Why is this a nonblocking allocation? It would seem more robust to use GFP_NOFS here.
Tom.
> > /* In SMB3.11 preauth integrity supersedes validate negotiate */ > if (tcon->ses->server->dialect == SMB311_PROT_ID) > @@ -764,63 +767,63 @@ int smb3_validate_negotiate(const unsigned int xid, struct cifs_tcon *tcon) > if (tcon->ses->session_flags & SMB2_SESSION_FLAG_IS_NULL) > cifs_dbg(VFS, "Unexpected null user (anonymous) auth flag sent by server\n"); > > - vneg_inbuf.Capabilities = > + pneg_inbuf->Capabilities = > cpu_to_le32(tcon->ses->server->vals->req_capabilities); > - memcpy(vneg_inbuf.Guid, tcon->ses->server->client_guid, > + memcpy(pneg_inbuf->Guid, tcon->ses->server->client_guid, > SMB2_CLIENT_GUID_SIZE); > > if (tcon->ses->sign) > - vneg_inbuf.SecurityMode = > + pneg_inbuf->SecurityMode = > cpu_to_le16(SMB2_NEGOTIATE_SIGNING_REQUIRED); > else if (global_secflags & CIFSSEC_MAY_SIGN) > - vneg_inbuf.SecurityMode = > + pneg_inbuf->SecurityMode = > cpu_to_le16(SMB2_NEGOTIATE_SIGNING_ENABLED); > else > - vneg_inbuf.SecurityMode = 0; > + pneg_inbuf->SecurityMode = 0; > > > if (strcmp(tcon->ses->server->vals->version_string, > SMB3ANY_VERSION_STRING) == 0) { > - vneg_inbuf.Dialects[0] = cpu_to_le16(SMB30_PROT_ID); > - vneg_inbuf.Dialects[1] = cpu_to_le16(SMB302_PROT_ID); > - vneg_inbuf.DialectCount = cpu_to_le16(2); > + pneg_inbuf->Dialects[0] = cpu_to_le16(SMB30_PROT_ID); > + pneg_inbuf->Dialects[1] = cpu_to_le16(SMB302_PROT_ID); > + pneg_inbuf->DialectCount = cpu_to_le16(2); > /* structure is big enough for 3 dialects, sending only 2 */ > inbuflen = sizeof(struct validate_negotiate_info_req) - 2; > } else if (strcmp(tcon->ses->server->vals->version_string, > SMBDEFAULT_VERSION_STRING) == 0) { > - vneg_inbuf.Dialects[0] = cpu_to_le16(SMB21_PROT_ID); > - vneg_inbuf.Dialects[1] = cpu_to_le16(SMB30_PROT_ID); > - vneg_inbuf.Dialects[2] = cpu_to_le16(SMB302_PROT_ID); > - vneg_inbuf.DialectCount = cpu_to_le16(3); > + pneg_inbuf->Dialects[0] = cpu_to_le16(SMB21_PROT_ID); > + pneg_inbuf->Dialects[1] = cpu_to_le16(SMB30_PROT_ID); > + pneg_inbuf->Dialects[2] = cpu_to_le16(SMB302_PROT_ID); > + pneg_inbuf->DialectCount = cpu_to_le16(3); > /* structure is big enough for 3 dialects */ > inbuflen = sizeof(struct validate_negotiate_info_req); > } else { > /* otherwise specific dialect was requested */ > - vneg_inbuf.Dialects[0] = > + pneg_inbuf->Dialects[0] = > cpu_to_le16(tcon->ses->server->vals->protocol_id); > - vneg_inbuf.DialectCount = cpu_to_le16(1); > + pneg_inbuf->DialectCount = cpu_to_le16(1); > /* structure is big enough for 3 dialects, sending only 1 */ > inbuflen = sizeof(struct validate_negotiate_info_req) - 4; > } > > - rc = SMB2_ioctl(xid, tcon, NO_FILE_ID, NO_FILE_ID, > + ret = SMB2_ioctl(xid, tcon, NO_FILE_ID, NO_FILE_ID, > FSCTL_VALIDATE_NEGOTIATE_INFO, true /* is_fsctl */, > - (char *)&vneg_inbuf, sizeof(struct validate_negotiate_info_req), > + (char *)pneg_inbuf, sizeof(*pneg_inbuf), > (char **)&pneg_rsp, &rsplen); > > - if (rc != 0) { > - cifs_dbg(VFS, "validate protocol negotiate failed: %d\n", rc); > - return -EIO; > + if (ret) { > + cifs_dbg(VFS, "validate protocol negotiate failed: %d\n", ret); > + goto out_free_inbuf; > } > > - if (rsplen != sizeof(struct validate_negotiate_info_rsp)) { > + if (rsplen != sizeof(*pneg_rsp)) { > cifs_dbg(VFS, "invalid protocol negotiate response size: %d\n", > rsplen); > > /* relax check since Mac returns max bufsize allowed on ioctl */ > if ((rsplen > CIFSMaxBufSize) > || (rsplen < sizeof(struct validate_negotiate_info_rsp))) > - goto err_rsp_free; > + goto out_free_rsp; > } > > /* check validate negotiate info response matches what we got earlier */ > @@ -838,14 +841,16 @@ int smb3_validate_negotiate(const unsigned int xid, struct cifs_tcon *tcon) > > /* validate negotiate successful */ > cifs_dbg(FYI, "validate negotiate info successful\n"); > - kfree(pneg_rsp); > - return 0; > + rc = 0; > + goto out_free_rsp; > > vneg_out: > cifs_dbg(VFS, "protocol revalidation - security settings mismatch\n"); > -err_rsp_free: > +out_free_rsp: > kfree(pneg_rsp); > - return -EIO; > +out_free_inbuf: > + kfree(pneg_inbuf); > + return rc; > } > > enum securityEnum >
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