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133 lines
3.5 KiB
C
133 lines
3.5 KiB
C
/*
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Vendor Reset - Vendor Specific Reset
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Copyright (C) 2020 Geoffrey McRae <geoff@hostfission.com>
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Copyright (C) 2020 Adam Madsen <adam@ajmadsen.com>
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This program is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free Software
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Foundation; either version 2 of the License, or (at your option) any later
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version.
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This program is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
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PARTICULAR PURPOSE. See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along with
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this program; if not, write to the Free Software Foundation, Inc., 59 Temple
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Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/kallsyms.h>
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#include <linux/kernel.h>
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#include <linux/ftrace.h>
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#include <linux/kprobes.h>
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#include <linux/pci.h>
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#include <linux/version.h>
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#include "ftrace.h"
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/*
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* Much of this file was inspired by https://www.apriorit.com/dev-blog/546-hooking-linux-functions-2
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*
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* Honestly the whole removal of kallsyms_lookup_name is hella fishy, Google.
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* Thank you, Filip Pynckels
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* http://users.telenet.be/pynckels/2020-2-Linux-kernel-unexported-kallsyms-functions.pdf
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*/
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static int resolve_hook_address(struct ftrace_hook *hook)
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{
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struct kprobe kp = { .symbol_name = hook->name };
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if (register_kprobe(&kp))
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{
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pr_warn("unresolved symbol %s\n", hook->name);
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return -ENOENT;
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}
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hook->address = (unsigned long)kp.addr;
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unregister_kprobe(&kp);
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*((unsigned long *)hook->original) = hook->address;
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return 0;
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}
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#if (LINUX_VERSION_CODE < KERNEL_VERSION(5, 11, 0))
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static void notrace fh_trace_thunk(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *ops, struct pt_regs *regs)
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{
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#else
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static void notrace fh_trace_thunk(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *ops, struct ftrace_regs *fregs)
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{
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struct pt_regs *regs;
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regs = ftrace_get_regs(fregs);
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#endif
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struct ftrace_hook *hook = to_ftrace_hook(ops);
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if (!within_module(parent_ip, THIS_MODULE))
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regs->ip = (unsigned long)hook->function;
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}
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int fh_install_hook(struct ftrace_hook *hook)
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{
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int err;
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err = resolve_hook_address(hook);
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if (err)
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return err;
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hook->ops.func = fh_trace_thunk;
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hook->ops.flags = FTRACE_OPS_FL_SAVE_REGS |
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FTRACE_OPS_FL_IPMODIFY;
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err = ftrace_set_filter_ip(&hook->ops, hook->address, 0, 0);
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if (err)
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{
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pr_warn("ftrace_set_filter_ip() failed: %d\n", err);
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return err;
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}
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err = register_ftrace_function(&hook->ops);
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if (err)
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{
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pr_warn("register_ftrace_function() failed in fh_install_hook: %d\n", err);
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ftrace_set_filter_ip(&hook->ops, hook->address, 1, 0);
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return err;
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}
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return 0;
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}
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void fh_remove_hook(struct ftrace_hook *hook)
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{
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int err;
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err = unregister_ftrace_function(&hook->ops);
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if (err)
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{
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pr_warn("unregister_ftrace_function() failed: %d\n", err);
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}
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err = ftrace_set_filter_ip(&hook->ops, hook->address, 1, 0);
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if (err)
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{
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pr_warn("ftrace_set_filter_ip() failed in fh_remove_hook: %d\n", err);
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}
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}
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int fh_install_hooks(struct ftrace_hook *hooks)
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{
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int ret;
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struct ftrace_hook *hook;
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for (hook = hooks; hook->name; ++hook)
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if ((ret = fh_install_hook(hook)))
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return ret;
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return 0;
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}
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void fh_remove_hooks(struct ftrace_hook *hooks)
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{
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struct ftrace_hook *hook;
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for (hook = hooks; hook->name; ++hook)
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fh_remove_hook(hook);
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}
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