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authorSteve French <stfrench@microsoft.com>2021-05-01 00:14:45 +0200
committerSteve French <stfrench@microsoft.com>2021-05-03 18:43:37 +0200
commitaa22ebc3826be23a4b2f776c7ad5079c75611dec (patch)
treefe7468f03aaf3c21d423ffb21dd96f6f87c985d9 /fs/cifs
parentcifs: add shutdown support (diff)
downloadlinux-aa22ebc3826be23a4b2f776c7ad5079c75611dec.tar.xz
linux-aa22ebc3826be23a4b2f776c7ad5079c75611dec.zip
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: Shyam Prasad N <sprasad@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com>
Diffstat (limited to 'fs/cifs')
-rw-r--r--fs/cifs/cifs_ioctl.h19
-rw-r--r--fs/cifs/ioctl.c33
2 files changed, 52 insertions, 0 deletions
diff --git a/fs/cifs/cifs_ioctl.h b/fs/cifs/cifs_ioctl.h
index f262c64516bc..4a97fe12006b 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..7d9654f56edc 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 */