changed as suggested - see attached
On Fri, Apr 30, 2021 at 11:00 PM ronnie sahlberg
<ronniesahlberg@xxxxxxxxx> wrote:
>
> These elements should probably be [32] and not
> + __u8 smb3encryptionkey[SMB3_ENC_DEC_KEY_SIZE];
>
> Because this is now visible to userspace and we can not allow this to
> ever change.
> Because when GCM512 is eventually released, if we bump
> SMB3_ENC_DEC_KEY_SIZE to a larger value we suddenly break userspace.
>
>
> On Sat, May 1, 2021 at 8:20 AM Steve French <smfrench@xxxxxxxxx> wrote:
> >
> > 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 <stfrench@xxxxxxxxxxxxx>
> > ---
> > 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[SMB3_ENC_DEC_KEY_SIZE];
> > + __u8 smb3decryptionkey[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, SMB3_ENC_DEC_KEY_SIZE);
> > + memcpy(pfull_key_inf.smb3encryptionkey,
> > + tcon->ses->smb3encryptionkey, 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 */
> >
> > --
> > Thanks,
> >
> > Steve
--
Thanks,
Steve
From a51a2ea0f8d72f0c3e691f253bb2b48db69cb035 Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@xxxxxxxxxxxxx>
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 <stfrench@xxxxxxxxxxxxx>
---
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
