Commit aa22ebc3 authored by Steve French's avatar Steve French
Browse files

smb3.1.1: allow dumping GCM256 keys to improve debugging of encrypted shares 



Previously we were only able to dump CCM or GCM-128 keys (see "smbinfo keys" e.g.)
to allow network debugging (e.g. wireshark) of mounts to SMB3.1.1 encrypted
shares.  But with the addition of GCM-256 support, we have to be able to dump
32 byte instead of 16 byte keys which requires adding an additional ioctl
for that.

Reviewed-by: default avatarShyam Prasad N <sprasad@microsoft.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 087f757b

fs/cifs/cifs_ioctl.h

+19 −0
Original line number Diff line number Diff line
@@ -57,6 +57,12 @@ struct smb_query_info { 
	/* char buffer[]; */

} __packed;



/*

 * Dumping the commonly used 16 byte (e.g. CCM and GCM128) keys still supported

 * for backlevel compatibility, but is not sufficient for dumping the less

 * frequently used GCM256 (32 byte) keys (see the newer "CIFS_DUMP_FULL_KEY"

 * ioctl for dumping decryption info for GCM256 mounts)

 */

struct smb3_key_debug_info {

	__u64	Suid;

	__u16	cipher_type;
@@ -65,6 +71,18 @@ struct smb3_key_debug_info { 
	__u8	smb3decryptionkey[SMB3_SIGN_KEY_SIZE];

} __packed;



/*

 * Dump full key (32 byte encrypt/decrypt keys instead of 16 bytes)

 * is needed if GCM256 (stronger encryption) negotiated

 */

struct smb3_full_key_debug_info {

	__u64	Suid;

	__u16	cipher_type;

	__u8	auth_key[16]; /* SMB2_NTLMV2_SESSKEY_SIZE */

	__u8	smb3encryptionkey[32]; /* SMB3_ENC_DEC_KEY_SIZE */

	__u8	smb3decryptionkey[32]; /* SMB3_ENC_DEC_KEY_SIZE */

} __packed;



struct smb3_notify {

	__u32	completion_filter;

	bool	watch_tree;
@@ -78,6 +96,7 @@ struct smb3_notify { 
#define CIFS_QUERY_INFO _IOWR(CIFS_IOCTL_MAGIC, 7, struct smb_query_info)

#define CIFS_DUMP_KEY _IOWR(CIFS_IOCTL_MAGIC, 8, struct smb3_key_debug_info)

#define CIFS_IOC_NOTIFY _IOW(CIFS_IOCTL_MAGIC, 9, struct smb3_notify)

#define CIFS_DUMP_FULL_KEY _IOWR(CIFS_IOCTL_MAGIC, 10, struct smb3_full_key_debug_info)

#define CIFS_IOC_SHUTDOWN _IOR ('X', 125, __u32)



/*

fs/cifs/ioctl.c

+33 −0
Original line number Diff line number Diff line
@@ -218,6 +218,7 @@ long cifs_ioctl(struct file *filep, unsigned int command, unsigned long arg) 
{

	struct inode *inode = file_inode(filep);

	struct smb3_key_debug_info pkey_inf;

	struct smb3_full_key_debug_info pfull_key_inf;

	int rc = -ENOTTY; /* strange error - but the precedent */

	unsigned int xid;

	struct cifsFileInfo *pSMBFile = filep->private_data;
@@ -354,6 +355,38 @@ long cifs_ioctl(struct file *filep, unsigned int command, unsigned long arg) 
			else

				rc = 0;

			break;

		/*

		 * Dump full key (32 bytes instead of 16 bytes) is

		 * needed if GCM256 (stronger encryption) negotiated

		 */

		case CIFS_DUMP_FULL_KEY:

			if (pSMBFile == NULL)

				break;

			if (!capable(CAP_SYS_ADMIN)) {

				rc = -EACCES;

				break;

			}



			tcon = tlink_tcon(pSMBFile->tlink);

			if (!smb3_encryption_required(tcon)) {

				rc = -EOPNOTSUPP;

				break;

			}

			pfull_key_inf.cipher_type =

				le16_to_cpu(tcon->ses->server->cipher_type);

			pfull_key_inf.Suid = tcon->ses->Suid;

			memcpy(pfull_key_inf.auth_key, tcon->ses->auth_key.response,

					16 /* SMB2_NTLMV2_SESSKEY_SIZE */);

			memcpy(pfull_key_inf.smb3decryptionkey,

			      tcon->ses->smb3decryptionkey, 32 /* SMB3_ENC_DEC_KEY_SIZE */);

			memcpy(pfull_key_inf.smb3encryptionkey,

			      tcon->ses->smb3encryptionkey, 32 /* SMB3_ENC_DEC_KEY_SIZE */);

			if (copy_to_user((void __user *)arg, &pfull_key_inf,

					sizeof(struct smb3_full_key_debug_info)))

				rc = -EFAULT;

			else

				rc = 0;

			break;

		case CIFS_IOC_NOTIFY:

			if (!S_ISDIR(inode->i_mode)) {

				/* Notify can only be done on directories */