[GIT] [CIFS] Allow user names longer than 32 bytes

[GIT] [CIFS] Allow user names longer than 32 bytes

[Steve French]

commit 355e57ca063338eb00ea067a7570bb5f136cc513
Author: Steve French <sfrench-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
Date:   Fri Feb 25 01:11:56 2011 -0600

    [CIFS] Allow user names longer than 32 bytes

    We artificially limited the user name to 32 bytes, but modern servers handle
    larger.  Set the maximum length to a reasonable 256, and make the user name
    string dynamically allocated rather than a fixed size in session structure.
    Also clean up old checkpatch warning.

    Signed-off-by: Steve French <sfrench-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>

diff --git a/fs/cifs/cifs_spnego.c b/fs/cifs/cifs_spnego.c
index 4dfba82..33d2213 100644
--- a/fs/cifs/cifs_spnego.c
+++ b/fs/cifs/cifs_spnego.c
@@ -113,7 +113,7 @@ cifs_get_spnego_key(struct cifsSesInfo *sesInfo)
 		   MAX_MECH_STR_LEN +
 		   UID_KEY_LEN + (sizeof(uid_t) * 2) +
 		   CREDUID_KEY_LEN + (sizeof(uid_t) * 2) +
-		   USER_KEY_LEN + strlen(sesInfo->userName) +
+		   USER_KEY_LEN + strlen(sesInfo->user_name) +
 		   PID_KEY_LEN + (sizeof(pid_t) * 2) + 1;

 	spnego_key = ERR_PTR(-ENOMEM);
@@ -153,7 +153,7 @@ cifs_get_spnego_key(struct cifsSesInfo *sesInfo)
 	sprintf(dp, ";creduid=0x%x", sesInfo->cred_uid);

 	dp = description + strlen(description);
-	sprintf(dp, ";user=%s", sesInfo->userName);
+	sprintf(dp, ";user=%s", sesInfo->user_name);

 	dp = description + strlen(description);
 	sprintf(dp, ";pid=0x%x", current->pid);
diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
index a51585f..e307a28 100644
--- a/fs/cifs/cifsencrypt.c
+++ b/fs/cifs/cifsencrypt.c
@@ -469,15 +469,15 @@ static int calc_ntlmv2_hash(struct cifsSesInfo
*ses, char *ntlmv2_hash,
 		return rc;
 	}

-	/* convert ses->userName to unicode and uppercase */
-	len = strlen(ses->userName);
+	/* convert ses->user_name to unicode and uppercase */
+	len = strlen(ses->user_name);
 	user = kmalloc(2 + (len * 2), GFP_KERNEL);
 	if (user == NULL) {
 		cERROR(1, "calc_ntlmv2_hash: user mem alloc failure\n");
 		rc = -ENOMEM;
 		goto calc_exit_2;
 	}
-	len = cifs_strtoUCS((__le16 *)user, ses->userName, len, nls_cp);
+	len = cifs_strtoUCS((__le16 *)user, ses->user_name, len, nls_cp);
 	UniStrupr(user);

 	crypto_shash_update(&ses->server->secmech.sdeschmacmd5->shash,
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 191ef2f..827f9c8 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -412,8 +412,8 @@ cifs_show_options(struct seq_file *s, struct vfsmount *m)

 	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MULTIUSER)
 		seq_printf(s, ",multiuser");
-	else if (tcon->ses->userName)
-		seq_printf(s, ",username=%s", tcon->ses->userName);
+	else if (tcon->ses->user_name)
+		seq_printf(s, ",username=%s", tcon->ses->user_name);

 	if (tcon->ses->domainName)
 		seq_printf(s, ",domain=%s", tcon->ses->domainName);
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index a17a86c..293b636 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -38,9 +38,8 @@
 #define MAX_TREE_SIZE (2 + MAX_SERVER_SIZE + 1 + MAX_SHARE_SIZE + 1)
 #define MAX_SERVER_SIZE 15
 #define MAX_SHARE_SIZE  64	/* used to be 20, this should still be enough */
-#define MAX_USERNAME_SIZE 32	/* 32 is to allow for 15 char names + null
-				   termination then *2 for unicode versions */
-#define MAX_PASSWORD_SIZE 512  /* max for windows seems to be 256 wide chars */
+#define MAX_USERNAME_SIZE 256	/* reasonable maximum for current servers */
+#define MAX_PASSWORD_SIZE 512	/* max for windows seems to be 256 wide chars */

 #define CIFS_MIN_RCV_POOL 4

@@ -285,7 +284,7 @@ struct cifsSesInfo {
 	int capabilities;
 	char serverName[SERVER_NAME_LEN_WITH_NULL * 2];	/* BB make bigger for
 				TCP names - will ipv6 and sctp addresses fit? */
-	char userName[MAX_USERNAME_SIZE + 1];
+	char *user_name;
 	char *domainName;
 	char *password;
 	struct session_key auth_key;
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index fe0fc61..6354ed5 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -882,7 +882,8 @@ cifs_parse_mount_options(char *options, const char *devname,
 				/* null user, ie anonymous, authentication */
 				vol->nullauth = 1;
 			}
-			if (strnlen(value, 200) < 200) {
+			if (strnlen(value, MAX_USERNAME_SIZE) <
+						MAX_USERNAME_SIZE) {
 				vol->username = value;
 			} else {
 				printk(KERN_WARNING "CIFS: username too long\n");
@@ -1825,7 +1826,9 @@ cifs_find_smb_ses(struct TCP_Server_Info
*server, struct smb_vol *vol)
 			break;
 		default:
 			/* anything else takes username/password */
-			if (strncmp(ses->userName, vol->username,
+			if (ses->user_name == NULL)
+				continue;
+			if (strncmp(ses->user_name, vol->username,
 				    MAX_USERNAME_SIZE))
 				continue;
 			if (strlen(vol->username) != 0 &&
@@ -1923,9 +1926,11 @@ cifs_get_smb_ses(struct TCP_Server_Info
*server, struct smb_vol *volume_info)
 	else
 		sprintf(ses->serverName, "%pI4", &addr->sin_addr);

-	if (volume_info->username)
-		strncpy(ses->userName, volume_info->username,
-			MAX_USERNAME_SIZE);
+	if (volume_info->username) {
+		ses->user_name = kstrdup(volume_info->username, GFP_KERNEL);
+		if (!ses->user_name)
+			goto get_ses_fail;
+	}

 	/* volume_info->password freed at unmount */
 	if (volume_info->password) {
diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index b90a4d3..e9e6f29 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -100,6 +100,7 @@ sesInfoFree(struct cifsSesInfo *buf_to_free)
 		memset(buf_to_free->password, 0, strlen(buf_to_free->password));
 		kfree(buf_to_free->password);
 	}
+	kfree(buf_to_free->user_name);
 	kfree(buf_to_free->domainName);
 	kfree(buf_to_free);
 }
diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
index c13e1e4..145e1c3 100644
--- a/fs/cifs/sess.c
+++ b/fs/cifs/sess.c
@@ -219,12 +219,12 @@ static void unicode_ssetup_strings(char
**pbcc_area, struct cifsSesInfo *ses,
 		bcc_ptr++;
 	} */
 	/* copy user */
-	if (ses->userName == NULL) {
+	if (ses->user_name == NULL) {
 		/* null user mount */
 		*bcc_ptr = 0;
 		*(bcc_ptr+1) = 0;
 	} else {
-		bytes_ret = cifs_strtoUCS((__le16 *) bcc_ptr, ses->userName,
+		bytes_ret = cifs_strtoUCS((__le16 *) bcc_ptr, ses->user_name,
 					  MAX_USERNAME_SIZE, nls_cp);
 	}
 	bcc_ptr += 2 * bytes_ret;
@@ -244,12 +244,11 @@ static void ascii_ssetup_strings(char
**pbcc_area, struct cifsSesInfo *ses,
 	/* copy user */
 	/* BB what about null user mounts - check that we do this BB */
 	/* copy user */
-	if (ses->userName == NULL) {
-		/* BB what about null user mounts - check that we do this BB */
-	} else {
-		strncpy(bcc_ptr, ses->userName, MAX_USERNAME_SIZE);
-	}
-	bcc_ptr += strnlen(ses->userName, MAX_USERNAME_SIZE);
+	if (ses->user_name != NULL)
+		strncpy(bcc_ptr, ses->user_name, MAX_USERNAME_SIZE);
+	/* else null user mount */
+
+	bcc_ptr += strnlen(ses->user_name, MAX_USERNAME_SIZE);
 	*bcc_ptr = 0;
 	bcc_ptr++; /* account for null termination */

@@ -523,14 +522,14 @@ static int build_ntlmssp_auth_blob(unsigned char *pbuffer,
 		tmp += len;
 	}

-	if (ses->userName == NULL) {
+	if (ses->user_name == NULL) {
 		sec_blob->UserName.BufferOffset = cpu_to_le32(tmp - pbuffer);
 		sec_blob->UserName.Length = 0;
 		sec_blob->UserName.MaximumLength = 0;
 		tmp += 2;
 	} else {
 		int len;
-		len = cifs_strtoUCS((__le16 *)tmp, ses->userName,
+		len = cifs_strtoUCS((__le16 *)tmp, ses->user_name,
 				    MAX_USERNAME_SIZE, nls_cp);
 		len *= 2; /* unicode is 2 bytes each */
 		sec_blob->UserName.BufferOffset = cpu_to_le32(tmp - pbuffer);

-- 
Thanks,

Steve

Re: [GIT] [CIFS] Allow user names longer than 32 bytes

[Steve French]

On Mon, Feb 28, 2011 at 12:59 PM, Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> On Fri, 25 Feb 2011 12:24:17 -0600
> Steve French <smfrench-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
>> commit 355e57ca063338eb00ea067a7570bb5f136cc513
>> Author: Steve French <sfrench-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
>> Date:   Fri Feb 25 01:11:56 2011 -0600
>>
>>     [CIFS] Allow user names longer than 32 bytes
>>
>>     We artificially limited the user name to 32 bytes, but modern servers handle
>>     larger.  Set the maximum length to a reasonable 256, and make the user name
>>     string dynamically allocated rather than a fixed size in session structure.
>>     Also clean up old checkpatch warning.
>>
>>     Signed-off-by: Steve French <sfrench-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
>
> [...]
>
>> diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
>> index a51585f..e307a28 100644
>> --- a/fs/cifs/cifsencrypt.c
>> +++ b/fs/cifs/cifsencrypt.c
>> @@ -469,15 +469,15 @@ static int calc_ntlmv2_hash(struct cifsSesInfo
>> *ses, char *ntlmv2_hash,
>>               return rc;
>>       }
>>
>> -     /* convert ses->userName to unicode and uppercase */
>> -     len = strlen(ses->userName);
>> +     /* convert ses->user_name to unicode and uppercase */
>> +     len = strlen(ses->user_name);
>>       user = kmalloc(2 + (len * 2), GFP_KERNEL);
>>       if (user == NULL) {
>>               cERROR(1, "calc_ntlmv2_hash: user mem alloc failure\n");
>>               rc = -ENOMEM;
>>               goto calc_exit_2;
>>       }
>> -     len = cifs_strtoUCS((__le16 *)user, ses->userName, len, nls_cp);
>> +     len = cifs_strtoUCS((__le16 *)user, ses->user_name, len, nls_cp);
>>       UniStrupr(user);
>>
>
> Now that user_name can be a NULL pointer, what prevents the code above
> from oopsing if no one passes in a user= parm?

I will doublecheck - I thought I had found a "userName" check earlier in
each of these 18 paths but will double check now.


-- 
Thanks,

Steve

Re: [GIT] [CIFS] Allow user names longer than 32 bytes

[Jeff Layton]

On Fri, 25 Feb 2011 12:24:17 -0600
Steve French <smfrench-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:

> commit 355e57ca063338eb00ea067a7570bb5f136cc513
> Author: Steve French <sfrench-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
> Date:   Fri Feb 25 01:11:56 2011 -0600
> 
>     [CIFS] Allow user names longer than 32 bytes
> 
>     We artificially limited the user name to 32 bytes, but modern servers handle
>     larger.  Set the maximum length to a reasonable 256, and make the user name
>     string dynamically allocated rather than a fixed size in session structure.
>     Also clean up old checkpatch warning.
> 
>     Signed-off-by: Steve French <sfrench-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>

[...]

> diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
> index a51585f..e307a28 100644
> --- a/fs/cifs/cifsencrypt.c
> +++ b/fs/cifs/cifsencrypt.c
> @@ -469,15 +469,15 @@ static int calc_ntlmv2_hash(struct cifsSesInfo
> *ses, char *ntlmv2_hash,
>  		return rc;
>  	}
> 
> -	/* convert ses->userName to unicode and uppercase */
> -	len = strlen(ses->userName);
> +	/* convert ses->user_name to unicode and uppercase */
> +	len = strlen(ses->user_name);
>  	user = kmalloc(2 + (len * 2), GFP_KERNEL);
>  	if (user == NULL) {
>  		cERROR(1, "calc_ntlmv2_hash: user mem alloc failure\n");
>  		rc = -ENOMEM;
>  		goto calc_exit_2;
>  	}
> -	len = cifs_strtoUCS((__le16 *)user, ses->userName, len, nls_cp);
> +	len = cifs_strtoUCS((__le16 *)user, ses->user_name, len, nls_cp);
>  	UniStrupr(user);
> 

Now that user_name can be a NULL pointer, what prevents the code above
from oopsing if no one passes in a user= parm?

-- 
Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

Re: [GIT] [CIFS] Allow user names longer than 32 bytes

[Jeff Layton]

On Mon, 28 Feb 2011 13:59:35 -0500
Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:

> On Fri, 25 Feb 2011 12:24:17 -0600
> Steve French <smfrench-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> 
> > commit 355e57ca063338eb00ea067a7570bb5f136cc513
> > Author: Steve French <sfrench-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
> > Date:   Fri Feb 25 01:11:56 2011 -0600
> > 
> >     [CIFS] Allow user names longer than 32 bytes
> > 
> >     We artificially limited the user name to 32 bytes, but modern servers handle
> >     larger.  Set the maximum length to a reasonable 256, and make the user name
> >     string dynamically allocated rather than a fixed size in session structure.
> >     Also clean up old checkpatch warning.
> > 
> >     Signed-off-by: Steve French <sfrench-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
> 
> [...]
> 
> > diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
> > index a51585f..e307a28 100644
> > --- a/fs/cifs/cifsencrypt.c
> > +++ b/fs/cifs/cifsencrypt.c
> > @@ -469,15 +469,15 @@ static int calc_ntlmv2_hash(struct cifsSesInfo
> > *ses, char *ntlmv2_hash,
> >  		return rc;
> >  	}
> > 
> > -	/* convert ses->userName to unicode and uppercase */
> > -	len = strlen(ses->userName);
> > +	/* convert ses->user_name to unicode and uppercase */
> > +	len = strlen(ses->user_name);
> >  	user = kmalloc(2 + (len * 2), GFP_KERNEL);
> >  	if (user == NULL) {
> >  		cERROR(1, "calc_ntlmv2_hash: user mem alloc failure\n");
> >  		rc = -ENOMEM;
> >  		goto calc_exit_2;
> >  	}
> > -	len = cifs_strtoUCS((__le16 *)user, ses->userName, len, nls_cp);
> > +	len = cifs_strtoUCS((__le16 *)user, ses->user_name, len, nls_cp);
> >  	UniStrupr(user);
> > 
> 
> Now that user_name can be a NULL pointer, what prevents the code above
> from oopsing if no one passes in a user= parm?
> 

Oh, and another problem too...

cifs_construct_tcon does a stack allocation for a temporary username field:

        char username[MAX_USERNAME_SIZE + 1];

That was probably ok when this was 33 bytes, but now that it's 257 it's
a little more scary. That should probably be switched to a kzalloc'ed
buffer too.

-- 
Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

Re: [GIT] [CIFS] Allow user names longer than 32 bytes

[Steve French]

Arggghh

Good catch - thx.

On Mon, Feb 28, 2011 at 1:04 PM, Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> On Mon, 28 Feb 2011 13:59:35 -0500
> Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
>
>> On Fri, 25 Feb 2011 12:24:17 -0600
>> Steve French <smfrench-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>>
>> > commit 355e57ca063338eb00ea067a7570bb5f136cc513
>> > Author: Steve French <sfrench-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
>> > Date:   Fri Feb 25 01:11:56 2011 -0600
>> >
>> >     [CIFS] Allow user names longer than 32 bytes
>> >
>> >     We artificially limited the user name to 32 bytes, but modern servers handle
>> >     larger.  Set the maximum length to a reasonable 256, and make the user name
>> >     string dynamically allocated rather than a fixed size in session structure.
>> >     Also clean up old checkpatch warning.
>> >
>> >     Signed-off-by: Steve French <sfrench-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
>>
>> [...]
>>
>> > diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
>> > index a51585f..e307a28 100644
>> > --- a/fs/cifs/cifsencrypt.c
>> > +++ b/fs/cifs/cifsencrypt.c
>> > @@ -469,15 +469,15 @@ static int calc_ntlmv2_hash(struct cifsSesInfo
>> > *ses, char *ntlmv2_hash,
>> >             return rc;
>> >     }
>> >
>> > -   /* convert ses->userName to unicode and uppercase */
>> > -   len = strlen(ses->userName);
>> > +   /* convert ses->user_name to unicode and uppercase */
>> > +   len = strlen(ses->user_name);
>> >     user = kmalloc(2 + (len * 2), GFP_KERNEL);
>> >     if (user == NULL) {
>> >             cERROR(1, "calc_ntlmv2_hash: user mem alloc failure\n");
>> >             rc = -ENOMEM;
>> >             goto calc_exit_2;
>> >     }
>> > -   len = cifs_strtoUCS((__le16 *)user, ses->userName, len, nls_cp);
>> > +   len = cifs_strtoUCS((__le16 *)user, ses->user_name, len, nls_cp);
>> >     UniStrupr(user);
>> >
>>
>> Now that user_name can be a NULL pointer, what prevents the code above
>> from oopsing if no one passes in a user= parm?
>>
>
> Oh, and another problem too...
>
> cifs_construct_tcon does a stack allocation for a temporary username field:
>
>        char username[MAX_USERNAME_SIZE + 1];
>
> That was probably ok when this was 33 bytes, but now that it's 257 it's
> a little more scary. That should probably be switched to a kzalloc'ed
> buffer too.
>
> --
> Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>



-- 
Thanks,

Steve

Re: [GIT] [CIFS] Allow user names longer than 32 bytes

[Steve French]

On Mon, Feb 28, 2011 at 12:59 PM, Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> On Fri, 25 Feb 2011 12:24:17 -0600
> Steve French <smfrench-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
>> commit 355e57ca063338eb00ea067a7570bb5f136cc513
>> Author: Steve French <sfrench-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
>> Date:   Fri Feb 25 01:11:56 2011 -0600
>>
>>     [CIFS] Allow user names longer than 32 bytes
>>
>>     We artificially limited the user name to 32 bytes, but modern servers handle
>>     larger.  Set the maximum length to a reasonable 256, and make the user name
>>     string dynamically allocated rather than a fixed size in session structure.
>>     Also clean up old checkpatch warning.
>>
>>     Signed-off-by: Steve French <sfrench-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
>
> [...]
>
>> diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
>> index a51585f..e307a28 100644
>> --- a/fs/cifs/cifsencrypt.c
>> +++ b/fs/cifs/cifsencrypt.c
>> @@ -469,15 +469,15 @@ static int calc_ntlmv2_hash(struct cifsSesInfo
>> *ses, char *ntlmv2_hash,
>>               return rc;
>>       }
>>
>> -     /* convert ses->userName to unicode and uppercase */
>> -     len = strlen(ses->userName);
>> +     /* convert ses->user_name to unicode and uppercase */
>> +     len = strlen(ses->user_name);
>>       user = kmalloc(2 + (len * 2), GFP_KERNEL);
>>       if (user == NULL) {
>>               cERROR(1, "calc_ntlmv2_hash: user mem alloc failure\n");
>>               rc = -ENOMEM;
>>               goto calc_exit_2;
>>       }
>> -     len = cifs_strtoUCS((__le16 *)user, ses->userName, len, nls_cp);
>> +     len = cifs_strtoUCS((__le16 *)user, ses->user_name, len, nls_cp);
>>       UniStrupr(user);
>>
>
> Now that user_name can be a NULL pointer, what prevents the code above
> from oopsing if no one passes in a user= parm?
>
> --
> Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>

In cifs_mount in fs/cifs/connect.c we guarantee that
volume_info->username is filled in (or we exit mount)

	if (volume_info->nullauth) {
		cFYI(1, "null user");
		volume_info->username = "";
	} else if (volume_info->username) {
		/* BB fixme parse for domain name here */
		cFYI(1, "Username: %s", volume_info->username);
	} else {
		cifserror("No username specified");
	/* In userspace mount helper we can get user name from alternate
	   locations such as env variables and files on disk */
		rc = -EINVAL;
		goto out;
	}

then in get_smb_ses (see below) when we allocate a new session we
either kstrdup successfully or we fail the mount:
	if (volume_info->username) {
		ses->user_name = kstrdup(volume_info->username, GFP_KERNEL);
		if (!ses->user_name)
			goto get_ses_fail;
	}


I don't mind adding defensive code in other places, but the reason the
null check is (only) in the find_cifs_smb_ses is in case an invalid
ses (being freed) was on the list.
-- 
Thanks,

Steve

Re: [GIT] [CIFS] Allow user names longer than 32 bytes

[Jeff Layton]

On Mon, 28 Feb 2011 15:09:00 -0600
Steve French <smfrench-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:

> On Mon, Feb 28, 2011 at 12:59 PM, Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> > On Fri, 25 Feb 2011 12:24:17 -0600
> > Steve French <smfrench-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> >
> >> commit 355e57ca063338eb00ea067a7570bb5f136cc513
> >> Author: Steve French <sfrench-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
> >> Date:   Fri Feb 25 01:11:56 2011 -0600
> >>
> >>     [CIFS] Allow user names longer than 32 bytes
> >>
> >>     We artificially limited the user name to 32 bytes, but modern servers handle
> >>     larger.  Set the maximum length to a reasonable 256, and make the user name
> >>     string dynamically allocated rather than a fixed size in session structure.
> >>     Also clean up old checkpatch warning.
> >>
> >>     Signed-off-by: Steve French <sfrench-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
> >
> > [...]
> >
> >> diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
> >> index a51585f..e307a28 100644
> >> --- a/fs/cifs/cifsencrypt.c
> >> +++ b/fs/cifs/cifsencrypt.c
> >> @@ -469,15 +469,15 @@ static int calc_ntlmv2_hash(struct cifsSesInfo
> >> *ses, char *ntlmv2_hash,
> >>               return rc;
> >>       }
> >>
> >> -     /* convert ses->userName to unicode and uppercase */
> >> -     len = strlen(ses->userName);
> >> +     /* convert ses->user_name to unicode and uppercase */
> >> +     len = strlen(ses->user_name);
> >>       user = kmalloc(2 + (len * 2), GFP_KERNEL);
> >>       if (user == NULL) {
> >>               cERROR(1, "calc_ntlmv2_hash: user mem alloc failure\n");
> >>               rc = -ENOMEM;
> >>               goto calc_exit_2;
> >>       }
> >> -     len = cifs_strtoUCS((__le16 *)user, ses->userName, len, nls_cp);
> >> +     len = cifs_strtoUCS((__le16 *)user, ses->user_name, len, nls_cp);
> >>       UniStrupr(user);
> >>
> >
> > Now that user_name can be a NULL pointer, what prevents the code above
> > from oopsing if no one passes in a user= parm?
> >
> > --
> > Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> >
> 
> In cifs_mount in fs/cifs/connect.c we guarantee that
> volume_info->username is filled in (or we exit mount)
> 
> 	if (volume_info->nullauth) {
> 		cFYI(1, "null user");
> 		volume_info->username = "";
> 	} else if (volume_info->username) {
> 		/* BB fixme parse for domain name here */
> 		cFYI(1, "Username: %s", volume_info->username);
> 	} else {
> 		cifserror("No username specified");
> 	/* In userspace mount helper we can get user name from alternate
> 	   locations such as env variables and files on disk */
> 		rc = -EINVAL;
> 		goto out;
> 	}
> 
> then in get_smb_ses (see below) when we allocate a new session we
> either kstrdup successfully or we fail the mount:
> 	if (volume_info->username) {
> 		ses->user_name = kstrdup(volume_info->username, GFP_KERNEL);
> 		if (!ses->user_name)
> 			goto get_ses_fail;
> 	}
> 
> 
> I don't mind adding defensive code in other places, but the reason the
> null check is (only) in the find_cifs_smb_ses is in case an invalid
> ses (being freed) was on the list.

That would be a bug and I think there would be better ways to check for
that if you think it's a possibility. I think we need to clearly define
the rules for this, and make the code follow those rules. There are two
possibilities:

1) it's possible to have a NULL user_name pointer. You always need to
check for that and deal with it appropriately.

...or...

2) it's not ever possible to have a NULL user_name pointer. Once the
ses has been created, NULL pointer checks are unneeded.

I'm ok with either, but I think it needs to be consistent. Checking for
a NULL pointer in only some places is very confusing.

-- 
Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>