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cifs: Allocate validate negotiation request through kmalloc

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The data buffer allocated on the stack can't be DMA'ed, ib_dma_map_page will
return an invalid DMA address for a buffer on stack. Even worse, this
incorrect address can't be detected by ib_dma_mapping_error. Sending data
from this address to hardware will not fail, but the remote peer will get
junk data.

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 several sizeof() to use *pointer in place of struct.

Changes in v4:
Added detailed comments on the failure through RDMA.
Allocate request buffer using GPF_NOFS.
Fixed possible memory leak.

Changes in v5:
Removed variable ret for checking return value.
Changed to use pneg_inbuf->Dialects[0] to calculate unused space in pneg_inbuf.

Fixes: ff1c038add ("Check SMB3 dialects against downgrade attacks")
Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Tom Talpey <ttalpey@microsoft.com>
This commit is contained in:
Long Li 2018-04-25 11:30:04 -07:00 committed by Steve French
parent 036db8bd96
commit 2796d303e3
1 changed files with 38 additions and 30 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

68
fs/cifs/smb2pdu.c
View file

@ -730,8 +730,8 @@ 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 rc;
struct validate_negotiate_info_req *pneg_inbuf;
struct validate_negotiate_info_rsp *pneg_rsp = NULL;
u32 rsplen;
u32 inbuflen; /* max of 4 dialects */
@ -765,63 +765,69 @@ 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 = kmalloc(sizeof(*pneg_inbuf), GFP_NOFS);
if (!pneg_inbuf)
return -ENOMEM;
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;
inbuflen = sizeof(*pneg_inbuf) -
sizeof(pneg_inbuf->Dialects[0]);
} 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);
inbuflen = sizeof(*pneg_inbuf);
} 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;
inbuflen = sizeof(*pneg_inbuf) -
sizeof(pneg_inbuf->Dialects[0]) * 2;
}
rc = 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_rsp, &rsplen);
(char *)pneg_inbuf, inbuflen, (char **)&pneg_rsp, &rsplen);
if (rc != 0) {
cifs_dbg(VFS, "validate protocol negotiate failed: %d\n", rc);
return -EIO;
rc = -EIO;
goto out_free_inbuf;
}
if (rsplen != sizeof(struct validate_negotiate_info_rsp)) {
rc = -EIO;
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;
if (rsplen > CIFSMaxBufSize || rsplen < sizeof(*pneg_rsp))
goto out_free_rsp;
}
/* check validate negotiate info response matches what we got earlier */
@ -838,15 +844,17 @@ int smb3_validate_negotiate(const unsigned int xid, struct cifs_tcon *tcon)
goto vneg_out;
/* validate negotiate successful */
rc = 0;
cifs_dbg(FYI, "validate negotiate info successful\n");
kfree(pneg_rsp);
return 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