[CIFS] Support for older servers which require plaintext passwords

disabled by default, but can be enabled via proc for servers which
require such support.  Also includes support for setting security
flags for cifs.  See fs/cifs/README

Signed-off-by: Steve French <sfrench@us.ibm.com>

3 files changed, 56 insertions, 16 deletions

diff --git a/fs/cifs/cifs_debug.c b/fs/cifs/cifs_debug.c
index 4e10e21c54fd..7c0015a96959 100644
--- a/fs/cifs/cifs_debug.c
+++ b/fs/cifs/cifs_debug.c
@@ -445,8 +445,8 @@ static read_proc_t traceSMB_read;
 static write_proc_t traceSMB_write;
 static read_proc_t multiuser_mount_read;
 static write_proc_t multiuser_mount_write;
-static read_proc_t extended_security_read;
-static write_proc_t extended_security_write;
+static read_proc_t security_flags_read;
+static write_proc_t security_flags_write;
 /* static read_proc_t ntlmv2_enabled_read;
 static write_proc_t ntlmv2_enabled_write;
 static read_proc_t packet_signing_enabled_read;
@@ -509,9 +509,9 @@ cifs_proc_init(void)
 
         pde =
             create_proc_read_entry("SecurityFlags", 0, proc_fs_cifs,
-                                extended_security_read, NULL);
+                                security_flags_read, NULL);
         if (pde)
-                pde->write_proc = extended_security_write;
+                pde->write_proc = security_flags_write;
 
         pde =
         create_proc_read_entry("LookupCacheEnabled", 0, proc_fs_cifs,
@@ -832,7 +832,7 @@ multiuser_mount_write(struct file *file, const char __user *buffer,
 }
 
 static int
-extended_security_read(char *page, char **start, off_t off,
+security_flags_read(char *page, char **start, off_t off,
                        int count, int *eof, void *data)
 {
         int len;
@@ -853,26 +853,50 @@ extended_security_read(char *page, char **start, off_t off,
         return len;
 }
 static int
-extended_security_write(struct file *file, const char __user *buffer,
+security_flags_write(struct file *file, const char __user *buffer,
                         unsigned long count, void *data)
 {
+        unsigned int flags;
+        char flags_string[12];
         char c;
-        int rc;
+
         cERROR(1,("size %ld",count)); /* BB removeme BB */
-        if((count < 2) || (count > 8))
+
+        if((count < 1) || (count > 11))
                 return -EINVAL;
 
-        rc = get_user(c, buffer);
+        memset(flags_string, 0, 12);
 
-/* BB fixme need to parse more characters in order to handle CIFSSEC flags */ 
+        if(copy_from_user(flags_string, buffer, count))
+                return -EFAULT;
 
-        if (rc)
-                return rc;
-        if (c == '0' || c == 'n' || c == 'N')
-                extended_security = CIFSSEC_DEF; /* default */
-        else if (c == '1' || c == 'y' || c == 'Y')
-                extended_security = CIFSSEC_MAX;
+        if(count < 3) {
+                /* single char or single char followed by null */
+                c = flags_string[0];
+                if (c == '0' || c == 'n' || c == 'N')
+                        extended_security = CIFSSEC_DEF; /* default */
+                else if (c == '1' || c == 'y' || c == 'Y')
+                        extended_security = CIFSSEC_MAX;
+                return count;
+        }
+        /* else we have a number */
+
+        flags = simple_strtoul(flags_string, NULL, 0);
+
+        cERROR(1,("sec flags 0x%x", flags));  /* BB FIXME make cFYI */
+
+        if(flags <= 0)  {
+                cERROR(1,("invalid security flags %s",flags_string));
+                return -EINVAL;
+        }
 
+        if((flags & CIFSSEC_MASK) != CIFSSEC_MASK) {
+                cERROR(1,("attempt to set unsupported security flags 0x%d",
+                        flags & ~CIFSSEC_MASK));
+                return -EINVAL;
+        }
+        /* flags look ok - update the global security flags for cifs module */
+        extended_security = flags;
         return count;
 }
 
diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
index e11d8c6bb227..3ae964bbfdc3 100644
--- a/fs/cifs/cifsencrypt.c
+++ b/fs/cifs/cifsencrypt.c
@@ -271,9 +271,18 @@ void calc_lanman_hash(struct cifsSesInfo * ses, char * lnm_session_key)
         int i;
         char password_with_pad[CIFS_ENCPWD_SIZE];
 
+        if(ses->server == NULL)
+                return;
+
         memset(password_with_pad, 0, CIFS_ENCPWD_SIZE);
         strncpy(password_with_pad, ses->password, CIFS_ENCPWD_SIZE);
 
+        if((ses->server->secMode & SECMODE_PW_ENCRYPT) == 0)
+                if(extended_security & CIFSSEC_MAY_PLNTXT) {
+                        memcpy(lnm_session_key, password_with_pad, CIFS_ENCPWD_SIZE); 
+                        return;
+                }
+
         /* calculate old style session key */
         /* calling toupper is less broken than repeatedly
         calling nls_toupper would be since that will never
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index b8c236be4d85..77cca3809467 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -492,6 +492,13 @@ CIFSSMBNegotiate(unsigned int xid, struct cifsSesInfo *ses)
                 server->secMode = pSMBr->SecurityMode;
                 if((server->secMode & SECMODE_USER) == 0)
                         cFYI(1,("share mode security"));
+
+                if((server->secMode & SECMODE_PW_ENCRYPT) == 0)
+#ifdef CONFIG_CIFS_WEAK_PW_HASH
+                        if ((extended_security & CIFSSEC_MAY_PLNTXT) == 0)
+#endif /* CIFS_WEAK_PW_HASH */
+                                cERROR(1,("Server requests plain text password"
+                                        " but client support disabled"));
                 
                 if(extended_security & CIFSSEC_MUST_NTLMV2)
                         server->secType = NTLMv2;