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- /* SPDX-License-Identifier: GPL-2.0 */
- /*
- * Return hooking with list-based shadow stack.
- */
- #ifndef _LINUX_RETHOOK_H
- #define _LINUX_RETHOOK_H
- #include <linux/compiler.h>
- #include <linux/freelist.h>
- #include <linux/kallsyms.h>
- #include <linux/llist.h>
- #include <linux/rcupdate.h>
- #include <linux/refcount.h>
- struct rethook_node;
- typedef void (*rethook_handler_t) (struct rethook_node *, void *, struct pt_regs *);
- /**
- * struct rethook - The rethook management data structure.
- * @data: The user-defined data storage.
- * @handler: The user-defined return hook handler.
- * @pool: The pool of struct rethook_node.
- * @ref: The reference counter.
- * @rcu: The rcu_head for deferred freeing.
- *
- * Don't embed to another data structure, because this is a self-destructive
- * data structure when all rethook_node are freed.
- */
- struct rethook {
- void *data;
- /*
- * To avoid sparse warnings, this uses a raw function pointer with
- * __rcu, instead of rethook_handler_t. But this must be same as
- * rethook_handler_t.
- */
- void (__rcu *handler) (struct rethook_node *, void *, struct pt_regs *);
- struct freelist_head pool;
- refcount_t ref;
- struct rcu_head rcu;
- };
- /**
- * struct rethook_node - The rethook shadow-stack entry node.
- * @freelist: The freelist, linked to struct rethook::pool.
- * @rcu: The rcu_head for deferred freeing.
- * @llist: The llist, linked to a struct task_struct::rethooks.
- * @rethook: The pointer to the struct rethook.
- * @ret_addr: The storage for the real return address.
- * @frame: The storage for the frame pointer.
- *
- * You can embed this to your extended data structure to store any data
- * on each entry of the shadow stack.
- */
- struct rethook_node {
- union {
- struct freelist_node freelist;
- struct rcu_head rcu;
- };
- struct llist_node llist;
- struct rethook *rethook;
- unsigned long ret_addr;
- unsigned long frame;
- };
- struct rethook *rethook_alloc(void *data, rethook_handler_t handler);
- void rethook_stop(struct rethook *rh);
- void rethook_free(struct rethook *rh);
- void rethook_add_node(struct rethook *rh, struct rethook_node *node);
- struct rethook_node *rethook_try_get(struct rethook *rh);
- void rethook_recycle(struct rethook_node *node);
- void rethook_hook(struct rethook_node *node, struct pt_regs *regs, bool mcount);
- unsigned long rethook_find_ret_addr(struct task_struct *tsk, unsigned long frame,
- struct llist_node **cur);
- /* Arch dependent code must implement arch_* and trampoline code */
- void arch_rethook_prepare(struct rethook_node *node, struct pt_regs *regs, bool mcount);
- void arch_rethook_trampoline(void);
- /**
- * is_rethook_trampoline() - Check whether the address is rethook trampoline
- * @addr: The address to be checked
- *
- * Return true if the @addr is the rethook trampoline address.
- */
- static inline bool is_rethook_trampoline(unsigned long addr)
- {
- return addr == (unsigned long)dereference_symbol_descriptor(arch_rethook_trampoline);
- }
- /* If the architecture needs to fixup the return address, implement it. */
- void arch_rethook_fixup_return(struct pt_regs *regs,
- unsigned long correct_ret_addr);
- /* Generic trampoline handler, arch code must prepare asm stub */
- unsigned long rethook_trampoline_handler(struct pt_regs *regs,
- unsigned long frame);
- #ifdef CONFIG_RETHOOK
- void rethook_flush_task(struct task_struct *tk);
- #else
- #define rethook_flush_task(tsk) do { } while (0)
- #endif
- #endif
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