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cifs: replace kfree() with kfree_sensitive() for sensitive data
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Replace kfree with kfree_sensitive, or prepend memzero_explicit() in
other cases, when freeing sensitive material that could still be left
in memory.

Signed-off-by: Enzo Matsumiya <ematsumiya@suse.de>
Reported-by: kernel test robot <oliver.sang@intel.com>
Link: https://lore.kernel.org/r/202209201529.ec633796-oliver.sang@intel.com
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Enzo Matsumiya authored and Steve French committed Oct 8, 2022
1 parent f5823f5 commit a4e430c
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Showing 7 changed files with 52 additions and 29 deletions.
12 changes: 6 additions & 6 deletions fs/cifs/cifsencrypt.c
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Original file line number Diff line number Diff line change
Expand Up @@ -679,7 +679,7 @@ setup_ntlmv2_rsp(struct cifs_ses *ses, const struct nls_table *nls_cp)
unlock:
cifs_server_unlock(ses->server);
setup_ntlmv2_rsp_ret:
kfree(tiblob);
kfree_sensitive(tiblob);

return rc;
}
Expand Down Expand Up @@ -753,14 +753,14 @@ cifs_crypto_secmech_release(struct TCP_Server_Info *server)
server->secmech.ccmaesdecrypt = NULL;
}

kfree(server->secmech.sdesccmacaes);
kfree_sensitive(server->secmech.sdesccmacaes);
server->secmech.sdesccmacaes = NULL;
kfree(server->secmech.sdeschmacsha256);
kfree_sensitive(server->secmech.sdeschmacsha256);
server->secmech.sdeschmacsha256 = NULL;
kfree(server->secmech.sdeschmacmd5);
kfree_sensitive(server->secmech.sdeschmacmd5);
server->secmech.sdeschmacmd5 = NULL;
kfree(server->secmech.sdescmd5);
kfree_sensitive(server->secmech.sdescmd5);
server->secmech.sdescmd5 = NULL;
kfree(server->secmech.sdescsha512);
kfree_sensitive(server->secmech.sdescsha512);
server->secmech.sdescsha512 = NULL;
}
6 changes: 3 additions & 3 deletions fs/cifs/connect.c
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Original file line number Diff line number Diff line change
Expand Up @@ -311,7 +311,7 @@ cifs_abort_connection(struct TCP_Server_Info *server)
}
server->sequence_number = 0;
server->session_estab = false;
kfree(server->session_key.response);
kfree_sensitive(server->session_key.response);
server->session_key.response = NULL;
server->session_key.len = 0;
server->lstrp = jiffies;
Expand Down Expand Up @@ -1580,7 +1580,7 @@ cifs_put_tcp_session(struct TCP_Server_Info *server, int from_reconnect)

cifs_crypto_secmech_release(server);

kfree(server->session_key.response);
kfree_sensitive(server->session_key.response);
server->session_key.response = NULL;
server->session_key.len = 0;
kfree(server->hostname);
Expand Down Expand Up @@ -4135,7 +4135,7 @@ cifs_setup_session(const unsigned int xid, struct cifs_ses *ses,
if (ses->auth_key.response) {
cifs_dbg(FYI, "Free previous auth_key.response = %p\n",
ses->auth_key.response);
kfree(ses->auth_key.response);
kfree_sensitive(ses->auth_key.response);
ses->auth_key.response = NULL;
ses->auth_key.len = 0;
}
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12 changes: 10 additions & 2 deletions fs/cifs/fs_context.c
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Original file line number Diff line number Diff line change
Expand Up @@ -791,6 +791,13 @@ do { \
cifs_sb->ctx->field = NULL; \
} while (0)

#define STEAL_STRING_SENSITIVE(cifs_sb, ctx, field) \
do { \
kfree_sensitive(ctx->field); \
ctx->field = cifs_sb->ctx->field; \
cifs_sb->ctx->field = NULL; \
} while (0)

static int smb3_reconfigure(struct fs_context *fc)
{
struct smb3_fs_context *ctx = smb3_fc2context(fc);
Expand All @@ -811,7 +818,7 @@ static int smb3_reconfigure(struct fs_context *fc)
STEAL_STRING(cifs_sb, ctx, UNC);
STEAL_STRING(cifs_sb, ctx, source);
STEAL_STRING(cifs_sb, ctx, username);
STEAL_STRING(cifs_sb, ctx, password);
STEAL_STRING_SENSITIVE(cifs_sb, ctx, password);
STEAL_STRING(cifs_sb, ctx, domainname);
STEAL_STRING(cifs_sb, ctx, nodename);
STEAL_STRING(cifs_sb, ctx, iocharset);
Expand Down Expand Up @@ -1162,7 +1169,7 @@ static int smb3_fs_context_parse_param(struct fs_context *fc,
}
break;
case Opt_pass:
kfree(ctx->password);
kfree_sensitive(ctx->password);
ctx->password = NULL;
if (strlen(param->string) == 0)
break;
Expand Down Expand Up @@ -1470,6 +1477,7 @@ static int smb3_fs_context_parse_param(struct fs_context *fc,
return 0;

cifs_parse_mount_err:
kfree_sensitive(ctx->password);
return -EINVAL;
}

Expand Down
2 changes: 1 addition & 1 deletion fs/cifs/misc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1119,7 +1119,7 @@ cifs_alloc_hash(const char *name,
void
cifs_free_hash(struct crypto_shash **shash, struct sdesc **sdesc)
{
kfree(*sdesc);
kfree_sensitive(*sdesc);
*sdesc = NULL;
if (*shash)
crypto_free_shash(*shash);
Expand Down
24 changes: 15 additions & 9 deletions fs/cifs/sess.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1213,6 +1213,12 @@ sess_alloc_buffer(struct sess_data *sess_data, int wct)
static void
sess_free_buffer(struct sess_data *sess_data)
{
int i;

/* zero the session data before freeing, as it might contain sensitive info (keys, etc) */
for (i = 0; i < 3; i++)
if (sess_data->iov[i].iov_base)
memzero_explicit(sess_data->iov[i].iov_base, sess_data->iov[i].iov_len);

free_rsp_buf(sess_data->buf0_type, sess_data->iov[0].iov_base);
sess_data->buf0_type = CIFS_NO_BUFFER;
Expand Down Expand Up @@ -1374,7 +1380,7 @@ sess_auth_ntlmv2(struct sess_data *sess_data)
sess_data->result = rc;
sess_data->func = NULL;
sess_free_buffer(sess_data);
kfree(ses->auth_key.response);
kfree_sensitive(ses->auth_key.response);
ses->auth_key.response = NULL;
}

Expand Down Expand Up @@ -1513,7 +1519,7 @@ sess_auth_kerberos(struct sess_data *sess_data)
sess_data->result = rc;
sess_data->func = NULL;
sess_free_buffer(sess_data);
kfree(ses->auth_key.response);
kfree_sensitive(ses->auth_key.response);
ses->auth_key.response = NULL;
}

Expand Down Expand Up @@ -1648,7 +1654,7 @@ sess_auth_rawntlmssp_negotiate(struct sess_data *sess_data)
rc = decode_ntlmssp_challenge(bcc_ptr, blob_len, ses);

out_free_ntlmsspblob:
kfree(ntlmsspblob);
kfree_sensitive(ntlmsspblob);
out:
sess_free_buffer(sess_data);

Expand All @@ -1658,9 +1664,9 @@ sess_auth_rawntlmssp_negotiate(struct sess_data *sess_data)
}

/* Else error. Cleanup */
kfree(ses->auth_key.response);
kfree_sensitive(ses->auth_key.response);
ses->auth_key.response = NULL;
kfree(ses->ntlmssp);
kfree_sensitive(ses->ntlmssp);
ses->ntlmssp = NULL;

sess_data->func = NULL;
Expand Down Expand Up @@ -1759,17 +1765,17 @@ sess_auth_rawntlmssp_authenticate(struct sess_data *sess_data)
}

out_free_ntlmsspblob:
kfree(ntlmsspblob);
kfree_sensitive(ntlmsspblob);
out:
sess_free_buffer(sess_data);

if (!rc)
rc = sess_establish_session(sess_data);

/* Cleanup */
kfree(ses->auth_key.response);
kfree_sensitive(ses->auth_key.response);
ses->auth_key.response = NULL;
kfree(ses->ntlmssp);
kfree_sensitive(ses->ntlmssp);
ses->ntlmssp = NULL;

sess_data->func = NULL;
Expand Down Expand Up @@ -1845,7 +1851,7 @@ int CIFS_SessSetup(const unsigned int xid, struct cifs_ses *ses,
rc = sess_data->result;

out:
kfree(sess_data);
kfree_sensitive(sess_data);
return rc;
}
#endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
6 changes: 3 additions & 3 deletions fs/cifs/smb2ops.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4423,11 +4423,11 @@ crypt_message(struct TCP_Server_Info *server, int num_rqst,
if (!rc && enc)
memcpy(&tr_hdr->Signature, sign, SMB2_SIGNATURE_SIZE);

kfree(iv);
kfree_sensitive(iv);
free_sg:
kfree(sg);
kfree_sensitive(sg);
free_req:
kfree(req);
kfree_sensitive(req);
return rc;
}

Expand Down
19 changes: 14 additions & 5 deletions fs/cifs/smb2pdu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1345,6 +1345,13 @@ SMB2_sess_alloc_buffer(struct SMB2_sess_data *sess_data)
static void
SMB2_sess_free_buffer(struct SMB2_sess_data *sess_data)
{
int i;

/* zero the session data before freeing, as it might contain sensitive info (keys, etc) */
for (i = 0; i < 2; i++)
if (sess_data->iov[i].iov_base)
memzero_explicit(sess_data->iov[i].iov_base, sess_data->iov[i].iov_len);

free_rsp_buf(sess_data->buf0_type, sess_data->iov[0].iov_base);
sess_data->buf0_type = CIFS_NO_BUFFER;
}
Expand Down Expand Up @@ -1477,6 +1484,8 @@ SMB2_auth_kerberos(struct SMB2_sess_data *sess_data)
out_put_spnego_key:
key_invalidate(spnego_key);
key_put(spnego_key);
if (rc)
kfree_sensitive(ses->auth_key.response);
out:
sess_data->result = rc;
sess_data->func = NULL;
Expand Down Expand Up @@ -1573,15 +1582,15 @@ SMB2_sess_auth_rawntlmssp_negotiate(struct SMB2_sess_data *sess_data)
}

out:
kfree(ntlmssp_blob);
memzero_explicit(ntlmssp_blob, blob_length);
SMB2_sess_free_buffer(sess_data);
if (!rc) {
sess_data->result = 0;
sess_data->func = SMB2_sess_auth_rawntlmssp_authenticate;
return;
}
out_err:
kfree(ses->ntlmssp);
kfree_sensitive(ses->ntlmssp);
ses->ntlmssp = NULL;
sess_data->result = rc;
sess_data->func = NULL;
Expand Down Expand Up @@ -1657,9 +1666,9 @@ SMB2_sess_auth_rawntlmssp_authenticate(struct SMB2_sess_data *sess_data)
}
#endif
out:
kfree(ntlmssp_blob);
memzero_explicit(ntlmssp_blob, blob_length);
SMB2_sess_free_buffer(sess_data);
kfree(ses->ntlmssp);
kfree_sensitive(ses->ntlmssp);
ses->ntlmssp = NULL;
sess_data->result = rc;
sess_data->func = NULL;
Expand Down Expand Up @@ -1737,7 +1746,7 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
cifs_server_dbg(VFS, "signing requested but authenticated as guest\n");
rc = sess_data->result;
out:
kfree(sess_data);
kfree_sensitive(sess_data);
return rc;
}

Expand Down

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