[PATCH] cifs: return ENAMETOOLONG for overlong names in cifs_open()/cifs_lookup()

[PATCH] cifs: return ENAMETOOLONG for overlong names in cifs_open()/cifs_lookup()

[Ronnie Sahlberg]

Add checking for the path component length and verify it is <= the maximum
that the server advertizes via FileFsAttributeInformation.

With this patch cifs.ko will now return ENAMETOOLONG instead of ENOENT
when users to access an overlong path.

To test this, try to cd into a (non-existing) directory on a CIFS share
that has a too long name:
cd /mnt/aaaaaaaaaaaaaaa...

and it now should show a good error message from the shell:
bash: cd: /mnt/aaaaaaaaaaaaaaaa...aaaaaa: File name too long

rh bz 1153996

Signed-off-by: Ronnie Sahlberg <lsahlber-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 fs/cifs/dir.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index 56366e984076..569d3fb736be 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -194,15 +194,20 @@ build_path_from_dentry_optional_prefix(struct dentry *direntry, bool prefix)
 }
 
 /*
+ * Don't allow path components longer than the server max.
  * Don't allow the separator character in a path component.
  * The VFS will not allow "/", but "\" is allowed by posix.
  */
 static int
-check_name(struct dentry *direntry)
+check_name(struct dentry *direntry, struct cifs_tcon *tcon)
 {
 	struct cifs_sb_info *cifs_sb = CIFS_SB(direntry->d_sb);
 	int i;
 
+	if (unlikely(direntry->d_name.len >
+		     tcon->fsAttrInfo.MaxPathNameComponentLength))
+		return -ENAMETOOLONG;
+
 	if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS)) {
 		for (i = 0; i < direntry->d_name.len; i++) {
 			if (direntry->d_name.name[i] == '\\') {
@@ -500,10 +505,6 @@ cifs_atomic_open(struct inode *inode, struct dentry *direntry,
 		return finish_no_open(file, res);
 	}
 
-	rc = check_name(direntry);
-	if (rc)
-		return rc;
-
 	xid = get_xid();
 
 	cifs_dbg(FYI, "parent inode = 0x%p name is: %pd and dentry = 0x%p\n",
@@ -516,6 +517,11 @@ cifs_atomic_open(struct inode *inode, struct dentry *direntry,
 	}
 
 	tcon = tlink_tcon(tlink);
+
+	rc = check_name(direntry, tcon);
+	if (rc)
+		goto out_free_xid;
+
 	server = tcon->ses->server;
 
 	if (server->ops->new_lease_key)
@@ -776,7 +782,7 @@ cifs_lookup(struct inode *parent_dir_inode, struct dentry *direntry,
 	}
 	pTcon = tlink_tcon(tlink);
 
-	rc = check_name(direntry);
+	rc = check_name(direntry, pTcon);
 	if (rc)
 		goto lookup_out;
 
-- 
2.13.3

Re: [PATCH] cifs: return ENAMETOOLONG for overlong names in cifs_open()/cifs_lookup()

[Steve French]

merged into cifs-2.6.git for-next and added cc: stable

On Tue, Aug 22, 2017 at 11:48 PM, Ronnie Sahlberg <lsahlber-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> Add checking for the path component length and verify it is <= the maximum
> that the server advertizes via FileFsAttributeInformation.
>
> With this patch cifs.ko will now return ENAMETOOLONG instead of ENOENT
> when users to access an overlong path.
>
> To test this, try to cd into a (non-existing) directory on a CIFS share
> that has a too long name:
> cd /mnt/aaaaaaaaaaaaaaa...
>
> and it now should show a good error message from the shell:
> bash: cd: /mnt/aaaaaaaaaaaaaaaa...aaaaaa: File name too long
>
> rh bz 1153996
>
> Signed-off-by: Ronnie Sahlberg <lsahlber-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> ---
>  fs/cifs/dir.c | 18 ++++++++++++------
>  1 file changed, 12 insertions(+), 6 deletions(-)
>
> diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
> index 56366e984076..569d3fb736be 100644
> --- a/fs/cifs/dir.c
> +++ b/fs/cifs/dir.c
> @@ -194,15 +194,20 @@ build_path_from_dentry_optional_prefix(struct dentry *direntry, bool prefix)
>  }
>
>  /*
> + * Don't allow path components longer than the server max.
>   * Don't allow the separator character in a path component.
>   * The VFS will not allow "/", but "\" is allowed by posix.
>   */
>  static int
> -check_name(struct dentry *direntry)
> +check_name(struct dentry *direntry, struct cifs_tcon *tcon)
>  {
>         struct cifs_sb_info *cifs_sb = CIFS_SB(direntry->d_sb);
>         int i;
>
> +       if (unlikely(direntry->d_name.len >
> +                    tcon->fsAttrInfo.MaxPathNameComponentLength))
> +               return -ENAMETOOLONG;
> +
>         if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS)) {
>                 for (i = 0; i < direntry->d_name.len; i++) {
>                         if (direntry->d_name.name[i] == '\\') {
> @@ -500,10 +505,6 @@ cifs_atomic_open(struct inode *inode, struct dentry *direntry,
>                 return finish_no_open(file, res);
>         }
>
> -       rc = check_name(direntry);
> -       if (rc)
> -               return rc;
> -
>         xid = get_xid();
>
>         cifs_dbg(FYI, "parent inode = 0x%p name is: %pd and dentry = 0x%p\n",
> @@ -516,6 +517,11 @@ cifs_atomic_open(struct inode *inode, struct dentry *direntry,
>         }
>
>         tcon = tlink_tcon(tlink);
> +
> +       rc = check_name(direntry, tcon);
> +       if (rc)
> +               goto out_free_xid;
> +
>         server = tcon->ses->server;
>
>         if (server->ops->new_lease_key)
> @@ -776,7 +782,7 @@ cifs_lookup(struct inode *parent_dir_inode, struct dentry *direntry,
>         }
>         pTcon = tlink_tcon(tlink);
>
> -       rc = check_name(direntry);
> +       rc = check_name(direntry, pTcon);
>         if (rc)
>                 goto lookup_out;
>
> --
> 2.13.3
>



-- 
Thanks,

Steve

Re: [PATCH] cifs: return ENAMETOOLONG for overlong names in cifs_open()/cifs_lookup()

[Steve French]

On Sun, Aug 27, 2017 at 5:01 PM, Steve French <smfrench-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> Had an endian warning - I fixed in followon patch (and cc: stable)
>
> Remember to make with sparse checking (and endian checking turned on)
>
> e.g.
> make C=1 M=fs/cifs modules CF=-D__CHECK_ENDIAN__
>
> On Tue, Aug 22, 2017 at 11:48 PM, Ronnie Sahlberg <lsahlber-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> wrote:
>>
>> Add checking for the path component length and verify it is <= the maximum
>> that the server advertizes via FileFsAttributeInformation.
>>
>> With this patch cifs.ko will now return ENAMETOOLONG instead of ENOENT
>> when users to access an overlong path.
>>
>> To test this, try to cd into a (non-existing) directory on a CIFS share
>> that has a too long name:
>> cd /mnt/aaaaaaaaaaaaaaa...
>>
>> and it now should show a good error message from the shell:
>> bash: cd: /mnt/aaaaaaaaaaaaaaaa...aaaaaa: File name too long
>>
>> rh bz 1153996
>>
>> Signed-off-by: Ronnie Sahlberg <lsahlber-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>> ---
>>  fs/cifs/dir.c | 18 ++++++++++++------
>>  1 file changed, 12 insertions(+), 6 deletions(-)
>>
>> diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
>> index 56366e984076..569d3fb736be 100644
>> --- a/fs/cifs/dir.c
>> +++ b/fs/cifs/dir.c
>> @@ -194,15 +194,20 @@ build_path_from_dentry_optional_prefix(struct dentry
>> *direntry, bool prefix)
>>  }
>>
>>  /*
>> + * Don't allow path components longer than the server max.
>>   * Don't allow the separator character in a path component.
>>   * The VFS will not allow "/", but "\" is allowed by posix.
>>   */
>>  static int
>> -check_name(struct dentry *direntry)
>> +check_name(struct dentry *direntry, struct cifs_tcon *tcon)
>>  {
>>         struct cifs_sb_info *cifs_sb = CIFS_SB(direntry->d_sb);
>>         int i;
>>
>> +       if (unlikely(direntry->d_name.len >
>> +                    tcon->fsAttrInfo.MaxPathNameComponentLength))
>> +               return -ENAMETOOLONG;
>> +
>>         if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS)) {
>>                 for (i = 0; i < direntry->d_name.len; i++) {
>>                         if (direntry->d_name.name[i] == '\\') {
>> @@ -500,10 +505,6 @@ cifs_atomic_open(struct inode *inode, struct dentry
>> *direntry,
>>                 return finish_no_open(file, res);
>>         }
>>
>> -       rc = check_name(direntry);
>> -       if (rc)
>> -               return rc;
>> -
>>         xid = get_xid();
>>
>>         cifs_dbg(FYI, "parent inode = 0x%p name is: %pd and dentry =
>> 0x%p\n",
>> @@ -516,6 +517,11 @@ cifs_atomic_open(struct inode *inode, struct dentry
>> *direntry,
>>         }
>>
>>         tcon = tlink_tcon(tlink);
>> +
>> +       rc = check_name(direntry, tcon);
>> +       if (rc)
>> +               goto out_free_xid;
>> +
>>         server = tcon->ses->server;
>>
>>         if (server->ops->new_lease_key)
>> @@ -776,7 +782,7 @@ cifs_lookup(struct inode *parent_dir_inode, struct
>> dentry *direntry,
>>         }
>>         pTcon = tlink_tcon(tlink);
>>
>> -       rc = check_name(direntry);
>> +       rc = check_name(direntry, pTcon);
>>         if (rc)
>>                 goto lookup_out;
>>
>> --
>> 2.13.3
>>
>
>
>
> --
> Thanks,
>
> Steve



-- 
Thanks,

Steve