From a51a2ea0f8d72f0c3e691f253bb2b48db69cb035 Mon Sep 17 00:00:00 2001 From: Steve French Date: Fri, 30 Apr 2021 17:14:45 -0500 Subject: [PATCH 1/2] 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. Signed-off-by: Steve French --- fs/cifs/cifs_ioctl.h | 19 +++++++++++++++++++ fs/cifs/ioctl.c | 33 +++++++++++++++++++++++++++++++++ 2 files changed, 52 insertions(+) diff --git a/fs/cifs/cifs_ioctl.h b/fs/cifs/cifs_ioctl.h index f262c64516bc..9f2ed9cccb08 100644 --- a/fs/cifs/cifs_ioctl.h +++ b/fs/cifs/cifs_ioctl.h @@ -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) /* diff --git a/fs/cifs/ioctl.c b/fs/cifs/ioctl.c index ef41fa878793..e4321e2a27d2 100644 --- a/fs/cifs/ioctl.c +++ b/fs/cifs/ioctl.c @@ -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 */ -- 2.27.0