Minimal supplement to upstream Kernel Self Protection Project changes. Features already provided by SELinux + Yama and archs other than multiarch arm64 / x86_64 aren't in scope. Only tags have stable history. Shared IRC channel with KSPP: irc.libera.chat #linux-hardening
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Init method just allocates memory for new cfg, and assigns net_generic(net, caif_net_id). Despite there is synchronize_rcu() on error path in cfcnfg_create(), in real this function does not use global lists, so it looks like this synchronize_rcu() is some legacy inheritance. Exit method removes caif devices under rtnl_lock(). There could be a problem, if someone from foreign net pernet_operations dereference caif_net_id of this net. It's dereferenced in get_cfcnfg() and caif_device_list(). get_cfcnfg() is used from netdevice notifiers, where they are called under rtnl_lock(). The notifiers can't be called from foreign nets pernet_operations. Also, it's used from caif_disconnect_client() and from caif_connect_client(). The both of the functions work with caif socket, and there is the only possibility to have a socket, when the net is dead. This may happen only of the socket was created as kern using sk_alloc(). Grep by PF_CAIF shows we do not create kern caif sockets, so get_cfcnfg() is safe. caif_device_list() is used in netdevice notifiers and exit method under rtnl lock. Also, from caif_get() used in the netdev notifiers and in caif_flow_cb(). The last item is skb destructor. Since there are no kernel caif sockets nobody can send net a packet in parallel with init/exit, so this is also safe. So, these pernet_operations are safe to be async. Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Signed-off-by: David S. Miller <davem@davemloft.net> |
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Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.