Commit 69f030cf authored by Junyi Liu's avatar Junyi Liu Committed by Steve French
Browse files

ksmbd: validate SID in parent security descriptor during ACL inheritance 



Introduce smb_validate_ntsd_sid() helper to safely validate Owner SID
and Group SID inside the NT Security Descriptor (smb_ntsd) retrieved
from the parent directory.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarJunyi Liu <moss80199@gmail.com>
Signed-off-by: default avatarNamjae Jeon <linkinjeon@kernel.org>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 35155033

fs/smb/server/smbacl.c

+50 −16
Original line number Diff line number Diff line
@@ -1096,6 +1096,40 @@ static int smb_append_inherited_ace(struct smb_ace **ace, int *nt_size, 
	return 0;

}



static int smb_validate_ntsd_sid(struct smb_ntsd *pntsd, size_t pntsd_size,

				  unsigned int sid_offset, struct smb_sid **sid,

				  size_t *sid_size)

{

	size_t sid_end;



	*sid = NULL;

	*sid_size = 0;



	if (!sid_offset)

		return 0;



	if (sid_offset < sizeof(struct smb_ntsd) ||

	    check_add_overflow(sid_offset, (size_t)CIFS_SID_BASE_SIZE,

			       &sid_end) ||

	    sid_end > pntsd_size)

		return -EINVAL;



	*sid = (struct smb_sid *)((char *)pntsd + sid_offset);

	if ((*sid)->num_subauth > SID_MAX_SUB_AUTHORITIES)

		return -EINVAL;



	if (check_add_overflow((size_t)CIFS_SID_BASE_SIZE,

			       sizeof(__le32) * (size_t)(*sid)->num_subauth,

			       &sid_end))

		return -EINVAL;



	if (sid_offset > pntsd_size || sid_end > pntsd_size - sid_offset)

		return -EINVAL;



	*sid_size = sid_end;

	return 0;

}



int smb_inherit_dacl(struct ksmbd_conn *conn,

		     const struct path *path,

		     unsigned int uid, unsigned int gid)
@@ -1108,28 +1142,28 @@ int smb_inherit_dacl(struct ksmbd_conn *conn, 
	struct dentry *parent = path->dentry->d_parent;

	struct mnt_idmap *idmap = mnt_idmap(path->mnt);

	int inherited_flags = 0, flags = 0, i, nt_size = 0, pdacl_size;

	int rc = 0, pntsd_type, pntsd_size, acl_len, aces_size;

	int rc = 0, pntsd_type, ppntsd_size, acl_len, aces_size;

	unsigned int dacloffset;

	size_t dacl_struct_end;

	u16 num_aces, ace_cnt = 0;

	char *aces_base;

	bool is_dir = S_ISDIR(d_inode(path->dentry)->i_mode);



	pntsd_size = ksmbd_vfs_get_sd_xattr(conn, idmap,

	ppntsd_size = ksmbd_vfs_get_sd_xattr(conn, idmap,

					    parent, &parent_pntsd);

	if (pntsd_size <= 0)

	if (ppntsd_size <= 0)

		return -ENOENT;



	dacloffset = le32_to_cpu(parent_pntsd->dacloffset);

	if (!dacloffset ||

	    check_add_overflow(dacloffset, sizeof(struct smb_acl), &dacl_struct_end) ||

	    dacl_struct_end > (size_t)pntsd_size) {

	    dacl_struct_end > (size_t)ppntsd_size) {

		rc = -EINVAL;

		goto free_parent_pntsd;

	}



	parent_pdacl = (struct smb_acl *)((char *)parent_pntsd + dacloffset);

	acl_len = pntsd_size - dacloffset;

	acl_len = ppntsd_size - dacloffset;

	num_aces = le16_to_cpu(parent_pdacl->num_aces);

	pntsd_type = le16_to_cpu(parent_pntsd->type);

	pdacl_size = le16_to_cpu(parent_pdacl->size);
@@ -1243,19 +1277,19 @@ int smb_inherit_dacl(struct ksmbd_conn *conn, 
		struct smb_ntsd *pntsd;

		struct smb_acl *pdacl;

		struct smb_sid *powner_sid = NULL, *pgroup_sid = NULL;

		int powner_sid_size = 0, pgroup_sid_size = 0, pntsd_size;

		size_t powner_sid_size = 0, pgroup_sid_size = 0, pntsd_size;

		size_t pntsd_alloc_size;



		if (parent_pntsd->osidoffset) {

			powner_sid = (struct smb_sid *)((char *)parent_pntsd +

					le32_to_cpu(parent_pntsd->osidoffset));

			powner_sid_size = 1 + 1 + 6 + (powner_sid->num_subauth * 4);

		}

		if (parent_pntsd->gsidoffset) {

			pgroup_sid = (struct smb_sid *)((char *)parent_pntsd +

					le32_to_cpu(parent_pntsd->gsidoffset));

			pgroup_sid_size = 1 + 1 + 6 + (pgroup_sid->num_subauth * 4);

		}

		rc = smb_validate_ntsd_sid(parent_pntsd, ppntsd_size,

					   le32_to_cpu(parent_pntsd->osidoffset),

					   &powner_sid, &powner_sid_size);

		if (rc)

			goto free_aces_base;

		rc = smb_validate_ntsd_sid(parent_pntsd, ppntsd_size,

					   le32_to_cpu(parent_pntsd->gsidoffset),

					   &pgroup_sid, &pgroup_sid_size);

		if (rc)

			goto free_aces_base;



		if (check_add_overflow(sizeof(struct smb_ntsd),

				       (size_t)powner_sid_size,