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linux/fs/smb/client/ioctl.c
Piyush Sachdeva 5be7a0cef3 smb: client: Use FullSessionKey for AES-256 encryption key derivation 
When Kerberos authentication is used with AES-256 encryption (AES-256-CCM
or AES-256-GCM), the SMB3 encryption and decryption keys must be derived
using the full session key (Session.FullSessionKey) rather than just the
first 16 bytes (Session.SessionKey).

Per MS-SMB2 section 3.2.5.3.1, when Connection.Dialect is "3.1.1" and
Connection.CipherId is AES-256-CCM or AES-256-GCM, Session.FullSessionKey
must be set to the full cryptographic key from the GSS authentication
context. The encryption and decryption key derivation (SMBC2SCipherKey,
SMBS2CCipherKey) must use this FullSessionKey as the KDF input. The
signing key derivation continues to use Session.SessionKey (first 16
bytes) in all cases.

Previously, generate_key() hardcoded SMB2_NTLMV2_SESSKEY_SIZE (16) as the
HMAC-SHA256 key input length for all derivations. When Kerberos with
AES-256 provides a 32-byte session key, the KDF for encryption/decryption
was using only the first 16 bytes, producing keys that did not match the
server's, causing mount failures with sec=krb5 and require_gcm_256=1.

Add a full_key_size parameter to generate_key() and pass the appropriate
size from generate_smb3signingkey():
 - Signing: always SMB2_NTLMV2_SESSKEY_SIZE (16 bytes)
 - Encryption/Decryption: ses->auth_key.len when AES-256, otherwise 16

Also fix cifs_dump_full_key() to report the actual session key length for
AES-256 instead of hardcoded CIFS_SESS_KEY_SIZE, so that userspace tools
like Wireshark receive the correct key for decryption.

Cc: <stable@vger.kernel.org>
Reviewed-by: Bharath SM <bharathsm@microsoft.com>
Signed-off-by: Piyush Sachdeva <psachdeva@microsoft.com>
Signed-off-by: Piyush Sachdeva <s.piyush1024@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
2026-05-07 14:09:01 -05:00

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// SPDX-License-Identifier: LGPL-2.1
/*
*
* vfs operations that deal with io control
*
* Copyright (C) International Business Machines Corp., 2005,2013
* Author(s): Steve French (sfrench@us.ibm.com)
*
*/
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/mount.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_debug.h"
#include "cifsfs.h"
#include "cifs_ioctl.h"
#include "smb2proto.h"
#include "smb2glob.h"
#include <linux/btrfs.h>
static long cifs_ioctl_query_info(unsigned int xid, struct file *filep,
unsigned long p)
{
struct inode *inode = file_inode(filep);
struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
struct dentry *dentry = filep->f_path.dentry;
const unsigned char *path;
void *page = alloc_dentry_path();
__le16 *utf16_path = NULL, root_path;
int rc = 0;
path = build_path_from_dentry(dentry, page);
if (IS_ERR(path)) {
free_dentry_path(page);
return PTR_ERR(path);
}
cifs_dbg(FYI, "%s %s\n", __func__, path);
if (!path[0]) {
root_path = 0;
utf16_path = &root_path;
} else {
utf16_path = cifs_convert_path_to_utf16(path + 1, cifs_sb);
if (!utf16_path) {
rc = -ENOMEM;
goto ici_exit;
}
}
if (tcon->ses->server->ops->ioctl_query_info)
rc = tcon->ses->server->ops->ioctl_query_info(
xid, tcon, cifs_sb, utf16_path,
filep->private_data ? 0 : 1, p);
else
rc = -EOPNOTSUPP;
ici_exit:
if (utf16_path != &root_path)
kfree(utf16_path);
free_dentry_path(page);
return rc;
}
static long cifs_ioctl_copychunk(unsigned int xid, struct file *dst_file,
unsigned long srcfd)
{
int rc;
struct inode *src_inode;
cifs_dbg(FYI, "ioctl copychunk range\n");
/* the destination must be opened for writing */
if (!(dst_file->f_mode & FMODE_WRITE)) {
cifs_dbg(FYI, "file target not open for write\n");
return -EINVAL;
}
/* check if target volume is readonly and take reference */
rc = mnt_want_write_file(dst_file);
if (rc) {
cifs_dbg(FYI, "mnt_want_write failed with rc %d\n", rc);
return rc;
}
CLASS(fd, src_file)(srcfd);
if (fd_empty(src_file)) {
rc = -EBADF;
goto out_drop_write;
}
if (fd_file(src_file)->f_op->unlocked_ioctl != cifs_ioctl) {
rc = -EBADF;
cifs_dbg(VFS, "src file seems to be from a different filesystem type\n");
goto out_drop_write;
}
src_inode = file_inode(fd_file(src_file));
rc = -EINVAL;
if (S_ISDIR(src_inode->i_mode))
goto out_drop_write;
rc = cifs_file_copychunk_range(xid, fd_file(src_file), 0, dst_file, 0,
src_inode->i_size, 0);
if (rc > 0)
rc = 0;
out_drop_write:
mnt_drop_write_file(dst_file);
return rc;
}
static long smb_mnt_get_tcon_info(struct cifs_tcon *tcon, void __user *arg)
{
int rc = 0;
struct smb_mnt_tcon_info tcon_inf;
tcon_inf.tid = tcon->tid;
tcon_inf.session_id = tcon->ses->Suid;
if (copy_to_user(arg, &tcon_inf, sizeof(struct smb_mnt_tcon_info)))
rc = -EFAULT;
return rc;
}
static long smb_mnt_get_fsinfo(unsigned int xid, struct cifs_tcon *tcon,
void __user *arg)
{
int rc = 0;
struct smb_mnt_fs_info *fsinf;
fsinf = kzalloc_obj(struct smb_mnt_fs_info);
if (fsinf == NULL)
return -ENOMEM;
fsinf->version = 1;
fsinf->protocol_id = tcon->ses->server->vals->protocol_id;
fsinf->tcon_flags = tcon->Flags;
fsinf->device_characteristics =
le32_to_cpu(tcon->fsDevInfo.DeviceCharacteristics);
fsinf->device_type = le32_to_cpu(tcon->fsDevInfo.DeviceType);
fsinf->fs_attributes = le32_to_cpu(tcon->fsAttrInfo.Attributes);
fsinf->max_path_component =
le32_to_cpu(tcon->fsAttrInfo.MaxPathNameComponentLength);
fsinf->vol_serial_number = tcon->vol_serial_number;
fsinf->vol_create_time = le64_to_cpu(tcon->vol_create_time);
fsinf->share_flags = tcon->share_flags;
fsinf->share_caps = le32_to_cpu(tcon->capabilities);
fsinf->sector_flags = tcon->ss_flags;
fsinf->optimal_sector_size = tcon->perf_sector_size;
fsinf->max_bytes_chunk = tcon->max_bytes_chunk;
fsinf->maximal_access = tcon->maximal_access;
fsinf->cifs_posix_caps = le64_to_cpu(tcon->fsUnixInfo.Capability);
if (copy_to_user(arg, fsinf, sizeof(struct smb_mnt_fs_info)))
rc = -EFAULT;
kfree(fsinf);
return rc;
}
static int cifs_shutdown(struct super_block *sb, unsigned long arg)
{
struct cifs_sb_info *sbi = CIFS_SB(sb);
struct tcon_link *tlink;
struct cifs_tcon *tcon;
__u32 flags;
int rc;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (get_user(flags, (__u32 __user *)arg))
return -EFAULT;
tlink = cifs_sb_tlink(sbi);
if (IS_ERR(tlink))
return PTR_ERR(tlink);
tcon = tlink_tcon(tlink);
trace_smb3_shutdown_enter(flags, tcon->tid);
if (flags > CIFS_GOING_FLAGS_NOLOGFLUSH) {
rc = -EINVAL;
goto shutdown_out_err;
}
if (cifs_forced_shutdown(sbi))
goto shutdown_good;
cifs_dbg(VFS, "shut down requested (%d)", flags);
/*
* see:
* https://man7.org/linux/man-pages/man2/ioctl_xfs_goingdown.2.html
* for more information and description of original intent of the flags
*/
switch (flags) {
/*
* We could add support later for default flag which requires:
* "Flush all dirty data and metadata to disk"
* would need to call syncfs or equivalent to flush page cache for
* the mount and then issue fsync to server (if nostrictsync not set)
*/
case CIFS_GOING_FLAGS_DEFAULT:
cifs_dbg(FYI, "shutdown with default flag not supported\n");
rc = -EINVAL;
goto shutdown_out_err;
/*
* FLAGS_LOGFLUSH is easy since it asks to write out metadata (not
* data) but metadata writes are not cached on the client, so can treat
* it similarly to NOLOGFLUSH
*/
case CIFS_GOING_FLAGS_LOGFLUSH:
case CIFS_GOING_FLAGS_NOLOGFLUSH:
atomic_or(CIFS_MOUNT_SHUTDOWN, &sbi->mnt_cifs_flags);
goto shutdown_good;
default:
rc = -EINVAL;
goto shutdown_out_err;
}
shutdown_good:
trace_smb3_shutdown_done(flags, tcon->tid);
cifs_put_tlink(tlink);
return 0;
shutdown_out_err:
trace_smb3_shutdown_err(rc, flags, tcon->tid);
cifs_put_tlink(tlink);
return rc;
}
static int cifs_dump_full_key(struct cifs_tcon *tcon, struct smb3_full_key_debug_info __user *in)
{
struct smb3_full_key_debug_info out;
struct cifs_ses *ses;
int rc = 0;
bool found = false;
u8 __user *end;
if (!smb3_encryption_required(tcon)) {
rc = -EOPNOTSUPP;
goto out;
}
/* copy user input into our output buffer */
if (copy_from_user(&out, in, sizeof(out))) {
rc = -EINVAL;
goto out;
}
if (!out.session_id) {
/* if ses id is 0, use current user session */
ses = tcon->ses;
} else {
/* otherwise if a session id is given, look for it in all our sessions */
struct cifs_ses *ses_it = NULL;
struct TCP_Server_Info *server_it = NULL;
spin_lock(&cifs_tcp_ses_lock);
list_for_each_entry(server_it, &cifs_tcp_ses_list, tcp_ses_list) {
list_for_each_entry(ses_it, &server_it->smb_ses_list, smb_ses_list) {
spin_lock(&ses_it->ses_lock);
if (ses_it->ses_status != SES_EXITING &&
ses_it->Suid == out.session_id) {
ses = ses_it;
/*
* since we are using the session outside the crit
* section, we need to make sure it won't be released
* so increment its refcount
*/
cifs_smb_ses_inc_refcount(ses);
spin_unlock(&ses_it->ses_lock);
found = true;
goto search_end;
}
spin_unlock(&ses_it->ses_lock);
}
}
search_end:
spin_unlock(&cifs_tcp_ses_lock);
if (!found) {
rc = -ENOENT;
goto out;
}
}
switch (ses->server->cipher_type) {
case SMB2_ENCRYPTION_AES128_CCM:
case SMB2_ENCRYPTION_AES128_GCM:
out.session_key_length = CIFS_SESS_KEY_SIZE;
out.server_in_key_length = out.server_out_key_length = SMB3_GCM128_CRYPTKEY_SIZE;
break;
case SMB2_ENCRYPTION_AES256_CCM:
case SMB2_ENCRYPTION_AES256_GCM:
out.session_key_length = ses->auth_key.len;
out.server_in_key_length = out.server_out_key_length = SMB3_GCM256_CRYPTKEY_SIZE;
break;
default:
rc = -EOPNOTSUPP;
goto out;
}
/* check if user buffer is big enough to store all the keys */
if (out.in_size < sizeof(out) + out.session_key_length + out.server_in_key_length
+ out.server_out_key_length) {
rc = -ENOBUFS;
goto out;
}
out.session_id = ses->Suid;
out.cipher_type = le16_to_cpu(ses->server->cipher_type);
/* overwrite user input with our output */
if (copy_to_user(in, &out, sizeof(out))) {
rc = -EINVAL;
goto out;
}
/* append all the keys at the end of the user buffer */
end = in->data;
if (copy_to_user(end, ses->auth_key.response, out.session_key_length)) {
rc = -EINVAL;
goto out;
}
end += out.session_key_length;
if (copy_to_user(end, ses->smb3encryptionkey, out.server_in_key_length)) {
rc = -EINVAL;
goto out;
}
end += out.server_in_key_length;
if (copy_to_user(end, ses->smb3decryptionkey, out.server_out_key_length)) {
rc = -EINVAL;
goto out;
}
out:
if (found)
cifs_put_smb_ses(ses);
return rc;
}
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;
int rc = -ENOTTY; /* strange error - but the precedent */
unsigned int xid;
struct cifsFileInfo *pSMBFile = filep->private_data;
struct cifs_tcon *tcon;
struct tcon_link *tlink;
struct cifs_sb_info *cifs_sb;
__u64 ExtAttrBits = 0;
#ifdef CONFIG_CIFS_POSIX
#ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
__u64 caps;
#endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
#endif /* CONFIG_CIFS_POSIX */
xid = get_xid();
cifs_dbg(FYI, "cifs ioctl 0x%x\n", command);
if (pSMBFile == NULL)
trace_smb3_ioctl(xid, 0, command);
else
trace_smb3_ioctl(xid, pSMBFile->fid.persistent_fid, command);
switch (command) {
case FS_IOC_GETFLAGS:
if (pSMBFile == NULL)
break;
tcon = tlink_tcon(pSMBFile->tlink);
#ifdef CONFIG_CIFS_POSIX
#ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
caps = le64_to_cpu(tcon->fsUnixInfo.Capability);
if (CIFS_UNIX_EXTATTR_CAP & caps) {
__u64 ExtAttrMask = 0;
rc = CIFSGetExtAttr(xid, tcon,
pSMBFile->fid.netfid,
&ExtAttrBits, &ExtAttrMask);
if (rc == 0)
rc = put_user(ExtAttrBits &
FS_FL_USER_VISIBLE,
(int __user *)arg);
if (rc != -EOPNOTSUPP)
break;
}
#endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
#endif /* CONFIG_CIFS_POSIX */
rc = 0;
if (CIFS_I(inode)->cifsAttrs & ATTR_COMPRESSED) {
/* add in the compressed bit */
ExtAttrBits = FS_COMPR_FL;
rc = put_user(ExtAttrBits & FS_FL_USER_VISIBLE,
(int __user *)arg);
}
break;
case FS_IOC_SETFLAGS:
if (pSMBFile == NULL)
break;
tcon = tlink_tcon(pSMBFile->tlink);
/* caps = le64_to_cpu(tcon->fsUnixInfo.Capability); */
if (get_user(ExtAttrBits, (int __user *)arg)) {
rc = -EFAULT;
break;
}
/*
* if (CIFS_UNIX_EXTATTR_CAP & caps)
* rc = CIFSSetExtAttr(xid, tcon,
* pSMBFile->fid.netfid,
* extAttrBits,
* &ExtAttrMask);
* if (rc != -EOPNOTSUPP)
* break;
*/
/* Currently only flag we can set is compressed flag */
if ((ExtAttrBits & FS_COMPR_FL) == 0)
break;
/* Try to set compress flag */
if (tcon->ses->server->ops->set_compression) {
rc = tcon->ses->server->ops->set_compression(
xid, tcon, pSMBFile);
cifs_dbg(FYI, "set compress flag rc %d\n", rc);
}
break;
case CIFS_IOC_COPYCHUNK_FILE:
rc = cifs_ioctl_copychunk(xid, filep, arg);
break;
case CIFS_QUERY_INFO:
rc = cifs_ioctl_query_info(xid, filep, arg);
break;
case CIFS_IOC_SET_INTEGRITY:
if (pSMBFile == NULL)
break;
tcon = tlink_tcon(pSMBFile->tlink);
if (tcon->ses->server->ops->set_integrity)
rc = tcon->ses->server->ops->set_integrity(xid,
tcon, pSMBFile);
else
rc = -EOPNOTSUPP;
break;
case CIFS_IOC_GET_MNT_INFO:
if (pSMBFile == NULL)
break;
tcon = tlink_tcon(pSMBFile->tlink);
rc = smb_mnt_get_fsinfo(xid, tcon, (void __user *)arg);
break;
case CIFS_IOC_GET_TCON_INFO:
cifs_sb = CIFS_SB(inode->i_sb);
tlink = cifs_sb_tlink(cifs_sb);
if (IS_ERR(tlink)) {
rc = PTR_ERR(tlink);
break;
}
tcon = tlink_tcon(tlink);
rc = smb_mnt_get_tcon_info(tcon, (void __user *)arg);
cifs_put_tlink(tlink);
break;
case CIFS_ENUMERATE_SNAPSHOTS:
if (pSMBFile == NULL)
break;
if (arg == 0) {
rc = -EINVAL;
goto cifs_ioc_exit;
}
tcon = tlink_tcon(pSMBFile->tlink);
if (tcon->ses->server->ops->enum_snapshots)
rc = tcon->ses->server->ops->enum_snapshots(xid, tcon,
pSMBFile, (void __user *)arg);
else
rc = -EOPNOTSUPP;
break;
case CIFS_DUMP_KEY:
/*
* Dump encryption keys. This is an old ioctl that only
* handles AES-128-{CCM,GCM}.
*/
if (!capable(CAP_SYS_ADMIN)) {
rc = -EACCES;
break;
}
cifs_sb = CIFS_SB(inode->i_sb);
tlink = cifs_sb_tlink(cifs_sb);
if (IS_ERR(tlink)) {
rc = PTR_ERR(tlink);
break;
}
tcon = tlink_tcon(tlink);
if (!smb3_encryption_required(tcon)) {
rc = -EOPNOTSUPP;
cifs_put_tlink(tlink);
break;
}
pkey_inf.cipher_type =
le16_to_cpu(tcon->ses->server->cipher_type);
pkey_inf.Suid = tcon->ses->Suid;
memcpy(pkey_inf.auth_key, tcon->ses->auth_key.response,
SMB2_NTLMV2_SESSKEY_SIZE);
memcpy(pkey_inf.smb3decryptionkey,
tcon->ses->smb3decryptionkey, SMB3_SIGN_KEY_SIZE);
memcpy(pkey_inf.smb3encryptionkey,
tcon->ses->smb3encryptionkey, SMB3_SIGN_KEY_SIZE);
if (copy_to_user((void __user *)arg, &pkey_inf,
sizeof(struct smb3_key_debug_info)))
rc = -EFAULT;
else
rc = 0;
cifs_put_tlink(tlink);
break;
case CIFS_DUMP_FULL_KEY:
/*
* Dump encryption keys (handles any key sizes)
*/
if (pSMBFile == NULL)
break;
if (!capable(CAP_SYS_ADMIN)) {
rc = -EACCES;
break;
}
cifs_sb = CIFS_SB(inode->i_sb);
tlink = cifs_sb_tlink(cifs_sb);
if (IS_ERR(tlink)) {
rc = PTR_ERR(tlink);
break;
}
tcon = tlink_tcon(tlink);
rc = cifs_dump_full_key(tcon, (void __user *)arg);
cifs_put_tlink(tlink);
break;
case CIFS_IOC_NOTIFY:
if (!S_ISDIR(inode->i_mode)) {
/* Notify can only be done on directories */
rc = -EOPNOTSUPP;
break;
}
cifs_sb = CIFS_SB(inode->i_sb);
tlink = cifs_sb_tlink(cifs_sb);
if (IS_ERR(tlink)) {
rc = PTR_ERR(tlink);
break;
}
tcon = tlink_tcon(tlink);
if (tcon && tcon->ses->server->ops->notify) {
rc = tcon->ses->server->ops->notify(xid,
filep, (void __user *)arg,
false /* no ret data */);
cifs_dbg(FYI, "ioctl notify rc %d\n", rc);
} else
rc = -EOPNOTSUPP;
cifs_put_tlink(tlink);
break;
case CIFS_IOC_NOTIFY_INFO:
if (!S_ISDIR(inode->i_mode)) {
/* Notify can only be done on directories */
rc = -EOPNOTSUPP;
break;
}
cifs_sb = CIFS_SB(inode->i_sb);
tlink = cifs_sb_tlink(cifs_sb);
if (IS_ERR(tlink)) {
rc = PTR_ERR(tlink);
break;
}
tcon = tlink_tcon(tlink);
if (tcon && tcon->ses->server->ops->notify) {
rc = tcon->ses->server->ops->notify(xid,
filep, (void __user *)arg,
true /* return details */);
cifs_dbg(FYI, "ioctl notify info rc %d\n", rc);
} else
rc = -EOPNOTSUPP;
cifs_put_tlink(tlink);
break;
case CIFS_IOC_SHUTDOWN:
rc = cifs_shutdown(inode->i_sb, arg);
break;
default:
cifs_dbg(FYI, "unsupported ioctl\n");
trace_smb3_unsupported_ioctl(xid,
pSMBFile ? pSMBFile->fid.persistent_fid : 0,
command);
break;
}
cifs_ioc_exit:
free_xid(xid);
return rc;
}
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