CIFSGetDFSRefer cleanup + dfs_referral_level_3 fixed to conform REFERRAL_V3 the MS-DFSC spec.

Signed-off-by: Igor Mammedov <niallain@gmail.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

2 files changed, 139 insertions, 82 deletions

diff --git a/fs/cifs/cifspdu.h b/fs/cifs/cifspdu.h
index c43bf4b7a556..93d5ee02a25b 100644
--- a/fs/cifs/cifspdu.h
+++ b/fs/cifs/cifspdu.h
@@ -1906,17 +1906,15 @@ typedef struct smb_com_transaction2_get_dfs_refer_req {
 
 typedef struct dfs_referral_level_3 {
         __le16 VersionNumber;
-        __le16 ReferralSize;
-        __le16 ServerType;      /* 0x0001 = CIFS server */
-        __le16 ReferralFlags;   /* or proximity - not clear which since it is
-                                   always set to zero - SNIA spec says 0x01
-                                   means strip off PathConsumed chars before
-                                   submitting RequestFileName to remote node */
-        __le16 TimeToLive;
-        __le16 Proximity;
+        __le16 Size;
+        __le16 ServerType; /* 0x0001 = root targets; 0x0000 = link targets */
+        __le16 ReferralEntryFlags; /* 0x0200 bit set only for domain
+                                      or DC referral responce */
+        __le32 TimeToLive;
         __le16 DfsPathOffset;
         __le16 DfsAlternatePathOffset;
-        __le16 NetworkAddressOffset;
+        __le16 NetworkAddressOffset; /* offset of the link target */
+        __le16 ServiceSiteGuid;
 } __attribute__((packed)) REFERRAL3;
 
 typedef struct smb_com_transaction_get_dfs_refer_rsp {
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index fc297383cb0e..6f8ed93a4ae8 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -81,6 +81,39 @@ static struct {
 #endif /* CONFIG_CIFS_WEAK_PW_HASH */
 #endif /* CIFS_POSIX */
 
+/* Allocates buffer into dst and copies smb string from src to it.
+ * caller is responsible for freeing dst if function returned 0.
+ * returns:
+ *      on success - 0
+ *      on failure - errno
+ */
+static int
+cifs_strncpy_to_host(char **dst, const char *src, const int maxlen,
+                 const bool is_unicode, const struct nls_table *nls_codepage)
+{
+        int plen;
+
+        if (is_unicode) {
+                plen = UniStrnlen((wchar_t *)src, maxlen);
+                *dst = kmalloc(plen + 2, GFP_KERNEL);
+                if (!*dst)
+                        goto cifs_strncpy_to_host_ErrExit;
+                cifs_strfromUCS_le(*dst, (__le16 *)src, plen, nls_codepage);
+        } else {
+                plen = strnlen(src, maxlen);
+                *dst = kmalloc(plen + 2, GFP_KERNEL);
+                if (!*dst)
+                        goto cifs_strncpy_to_host_ErrExit;
+                strncpy(*dst, src, plen);
+        }
+        (*dst)[plen] = 0;
+        return 0;
+
+cifs_strncpy_to_host_ErrExit:
+        cERROR(1, ("Failed to allocate buffer for string\n"));
+        return -ENOMEM;
+}
+
 
 /* Mark as invalid, all open files on tree connections since they
    were closed when session to server was lost */
@@ -3867,6 +3900,96 @@ GetInodeNumOut:
         return rc;
 }
 
+/* parses DFS refferal V3 structure
+ * caller is responsible for freeing target_nodes
+ * returns:
+ *      on success - 0
+ *      on failure - errno
+ */
+static int
+parse_DFS_REFERRALS(TRANSACTION2_GET_DFS_REFER_RSP *pSMBr,
+                unsigned int *num_of_nodes,
+                struct dfs_info3_param **target_nodes,
+                const struct nls_table *nls_codepage)
+{
+        int i, rc = 0;
+        char *data_end;
+        bool is_unicode;
+        struct dfs_referral_level_3 *ref;
+
+        is_unicode = pSMBr->hdr.Flags2 & SMBFLG2_UNICODE;
+        *num_of_nodes = le16_to_cpu(pSMBr->NumberOfReferrals);
+
+        if (*num_of_nodes < 1) {
+                cERROR(1, ("num_referrals: must be at least > 0,"
+                        "but we get num_referrals = %d\n", *num_of_nodes));
+                rc = -EINVAL;
+                goto parse_DFS_REFERRALS_exit;
+        }
+
+        ref = (struct dfs_referral_level_3 *) &(pSMBr->referrals);
+        if (ref->VersionNumber != 3) {
+                cERROR(1, ("Referrals of V%d version are not supported,"
+                        "should be V3", ref->VersionNumber));
+                rc = -EINVAL;
+                goto parse_DFS_REFERRALS_exit;
+        }
+
+        /* get the upper boundary of the resp buffer */
+        data_end = (char *)(&(pSMBr->PathConsumed)) +
+                                le16_to_cpu(pSMBr->t2.DataCount);
+
+        cFYI(1, ("num_referrals: %d dfs flags: 0x%x ... \n",
+                        *num_of_nodes,
+                        le16_to_cpu(pSMBr->DFSFlags)));
+
+        *target_nodes = kzalloc(sizeof(struct dfs_info3_param) *
+                        *num_of_nodes, GFP_KERNEL);
+        if (*target_nodes == NULL) {
+                cERROR(1, ("Failed to allocate buffer for target_nodes\n"));
+                rc = -ENOMEM;
+                goto parse_DFS_REFERRALS_exit;
+        }
+
+        /* collect neccessary data from referrals */
+        for (i = 0; i < *num_of_nodes; i++) {
+                char *temp;
+                int max_len;
+                struct dfs_info3_param *node = (*target_nodes)+i;
+
+                node->flags = le16_to_cpu(pSMBr->DFSFlags);
+                node->path_consumed = le16_to_cpu(pSMBr->PathConsumed);
+                node->server_type = le16_to_cpu(ref->ServerType);
+                node->ref_flag = le16_to_cpu(ref->ReferralEntryFlags);
+
+                /* copy DfsPath */
+                temp = (char *)ref + le16_to_cpu(ref->DfsPathOffset);
+                max_len = data_end - temp;
+                rc = cifs_strncpy_to_host(&(node->path_name), temp,
+                                        max_len, is_unicode, nls_codepage);
+                if (rc)
+                        goto parse_DFS_REFERRALS_exit;
+
+                /* copy link target UNC */
+                temp = (char *)ref + le16_to_cpu(ref->NetworkAddressOffset);
+                max_len = data_end - temp;
+                rc = cifs_strncpy_to_host(&(node->node_name), temp,
+                                        max_len, is_unicode, nls_codepage);
+                if (rc)
+                        goto parse_DFS_REFERRALS_exit;
+
+                ref += ref->Size;
+        }
+
+parse_DFS_REFERRALS_exit:
+        if (rc) {
+                free_dfs_info_array(*target_nodes, *num_of_nodes);
+                *target_nodes = NULL;
+                *num_of_nodes = 0;
+        }
+        return rc;
+}
+
 int
 CIFSGetDFSRefer(const int xid, struct cifsSesInfo *ses,
                 const unsigned char *searchName,
@@ -3877,12 +4000,9 @@ CIFSGetDFSRefer(const int xid, struct cifsSesInfo *ses,
 /* TRANS2_GET_DFS_REFERRAL */
         TRANSACTION2_GET_DFS_REFER_REQ *pSMB = NULL;
         TRANSACTION2_GET_DFS_REFER_RSP *pSMBr = NULL;
-        struct dfs_referral_level_3 *referrals = NULL;
         int rc = 0;
         int bytes_returned;
         int name_len;
-        unsigned int i;
-        char *temp;
         __u16 params, byte_count;
         *num_of_nodes = 0;
         *target_nodes = NULL;
@@ -3960,80 +4080,19 @@ getDFSRetry:
         rc = validate_t2((struct smb_t2_rsp *)pSMBr);
 
         /* BB Also check if enough total bytes returned? */
-        if (rc || (pSMBr->ByteCount < 17))
+        if (rc || (pSMBr->ByteCount < 17)) {
                 rc = -EIO;      /* bad smb */
-        else {
-                __u16 data_offset = le16_to_cpu(pSMBr->t2.DataOffset);
-                __u16 data_count = le16_to_cpu(pSMBr->t2.DataCount);
-
-                cFYI(1, ("Decoding GetDFSRefer response BCC: %d  Offset %d",
-                         pSMBr->ByteCount, data_offset));
-                referrals =
-                    (struct dfs_referral_level_3 *)
-                                (8 /* sizeof start of data block */ +
-                                data_offset +
-                                (char *) &pSMBr->hdr.Protocol);
-                cFYI(1, ("num_referrals: %d dfs flags: 0x%x ... \n"
-                        "for referral one refer size: 0x%x srv "
-                        "type: 0x%x refer flags: 0x%x ttl: 0x%x",
-                        le16_to_cpu(pSMBr->NumberOfReferrals),
-                        le16_to_cpu(pSMBr->DFSFlags),
-                        le16_to_cpu(referrals->ReferralSize),
-                        le16_to_cpu(referrals->ServerType),
-                        le16_to_cpu(referrals->ReferralFlags),
-                        le16_to_cpu(referrals->TimeToLive)));
-                /* BB This field is actually two bytes in from start of
-                   data block so we could do safety check that DataBlock
-                   begins at address of pSMBr->NumberOfReferrals */
-                *num_of_nodes = le16_to_cpu(pSMBr->NumberOfReferrals);
-
-                /* BB Fix below so can return more than one referral */
-                if (*num_of_nodes > 1)
-                        *num_of_nodes = 1;
-
-                /* get the length of the strings describing refs */
-                name_len = 0;
-                for (i = 0; i < *num_of_nodes; i++) {
-                        /* make sure that DfsPathOffset not past end */
-                        __u16 offset = le16_to_cpu(referrals->DfsPathOffset);
-                        if (offset > data_count) {
-                                /* if invalid referral, stop here and do
-                                not try to copy any more */
-                                *num_of_nodes = i;
-                                break;
-                        }
-                        temp = ((char *)referrals) + offset;
+                goto GetDFSRefExit;
+        }
 
-                        if (pSMBr->hdr.Flags2 & SMBFLG2_UNICODE) {
-                                name_len += UniStrnlen((wchar_t *)temp,
-                                                        data_count);
-                        } else {
-                                name_len += strnlen(temp, data_count);
-                        }
-                        referrals++;
-                        /* BB add check that referral pointer does
-                           not fall off end PDU */
-                }
-                /* BB add check for name_len bigger than bcc */
-                *target_nodes =
-                        kmalloc(name_len+1+(*num_of_nodes),
-                                GFP_KERNEL);
-                if (*target_nodes == NULL) {
-                        rc = -ENOMEM;
-                        goto GetDFSRefExit;
-                }
+        cFYI(1, ("Decoding GetDFSRefer response BCC: %d  Offset %d",
+                                pSMBr->ByteCount,
+                                le16_to_cpu(pSMBr->t2.DataOffset)));
 
-                referrals = (struct dfs_referral_level_3 *)
-                                (8 /* sizeof data hdr */ + data_offset +
-                                (char *) &pSMBr->hdr.Protocol);
+        /* parse returned result into more usable form */
+        rc = parse_DFS_REFERRALS(pSMBr, num_of_nodes,
+                                 target_nodes, nls_codepage);
 
-                for (i = 0; i < *num_of_nodes; i++) {
-                        temp = ((char *)referrals) +
-                                  le16_to_cpu(referrals->DfsPathOffset);
-                        /*  BB update target_uncs pointers */
-                        referrals++;
-                }
-        }
 GetDFSRefExit:
         if (pSMB)
                 cifs_buf_release(pSMB);