// SPDX-License-Identifier: GPL-2.0-only /* * Yama Linux Security Module * * Author: Kees Cook <[email protected]> * * Copyright (C) 2010 Canonical, Ltd. * Copyright (C) 2011 The Chromium OS Authors. */ #include <linux/lsm_hooks.h> #include <linux/sysctl.h> #include <linux/ptrace.h> #include <linux/prctl.h> #include <linux/ratelimit.h> #include <linux/workqueue.h> #include <linux/string_helpers.h> #include <linux/task_work.h> #include <linux/sched.h> #include <linux/spinlock.h> #include <uapi/linux/lsm.h> #define YAMA_SCOPE_DISABLED … #define YAMA_SCOPE_RELATIONAL … #define YAMA_SCOPE_CAPABILITY … #define YAMA_SCOPE_NO_ATTACH … static int ptrace_scope = …; /* describe a ptrace relationship for potential exception */ struct ptrace_relation { … }; static LIST_HEAD(ptracer_relations); static DEFINE_SPINLOCK(ptracer_relations_lock); static void yama_relation_cleanup(struct work_struct *work); static DECLARE_WORK(yama_relation_work, yama_relation_cleanup); struct access_report_info { … }; static void __report_access(struct callback_head *work) { … } /* defers execution because cmdline access can sleep */ static void report_access(const char *access, struct task_struct *target, struct task_struct *agent) { … } /** * yama_relation_cleanup - remove invalid entries from the relation list * @work: unused * */ static void yama_relation_cleanup(struct work_struct *work) { … } /** * yama_ptracer_add - add/replace an exception for this tracer/tracee pair * @tracer: the task_struct of the process doing the ptrace * @tracee: the task_struct of the process to be ptraced * * Each tracee can have, at most, one tracer registered. Each time this * is called, the prior registered tracer will be replaced for the tracee. * * Returns 0 if relationship was added, -ve on error. */ static int yama_ptracer_add(struct task_struct *tracer, struct task_struct *tracee) { … } /** * yama_ptracer_del - remove exceptions related to the given tasks * @tracer: remove any relation where tracer task matches * @tracee: remove any relation where tracee task matches */ static void yama_ptracer_del(struct task_struct *tracer, struct task_struct *tracee) { … } /** * yama_task_free - check for task_pid to remove from exception list * @task: task being removed */ static void yama_task_free(struct task_struct *task) { … } /** * yama_task_prctl - check for Yama-specific prctl operations * @option: operation * @arg2: argument * @arg3: argument * @arg4: argument * @arg5: argument * * Return 0 on success, -ve on error. -ENOSYS is returned when Yama * does not handle the given option. */ static int yama_task_prctl(int option, unsigned long arg2, unsigned long arg3, unsigned long arg4, unsigned long arg5) { … } /** * task_is_descendant - walk up a process family tree looking for a match * @parent: the process to compare against while walking up from child * @child: the process to start from while looking upwards for parent * * Returns 1 if child is a descendant of parent, 0 if not. */ static int task_is_descendant(struct task_struct *parent, struct task_struct *child) { … } /** * ptracer_exception_found - tracer registered as exception for this tracee * @tracer: the task_struct of the process attempting ptrace * @tracee: the task_struct of the process to be ptraced * * Returns 1 if tracer has a ptracer exception ancestor for tracee. */ static int ptracer_exception_found(struct task_struct *tracer, struct task_struct *tracee) { … } /** * yama_ptrace_access_check - validate PTRACE_ATTACH calls * @child: task that current task is attempting to ptrace * @mode: ptrace attach mode * * Returns 0 if following the ptrace is allowed, -ve on error. */ static int yama_ptrace_access_check(struct task_struct *child, unsigned int mode) { … } /** * yama_ptrace_traceme - validate PTRACE_TRACEME calls * @parent: task that will become the ptracer of the current task * * Returns 0 if following the ptrace is allowed, -ve on error. */ static int yama_ptrace_traceme(struct task_struct *parent) { … } static const struct lsm_id yama_lsmid = …; static struct security_hook_list yama_hooks[] __ro_after_init = …; #ifdef CONFIG_SYSCTL static int yama_dointvec_minmax(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { … } static int max_scope = …; static struct ctl_table yama_sysctl_table[] = …; static void __init yama_init_sysctl(void) { … } #else static inline void yama_init_sysctl(void) { } #endif /* CONFIG_SYSCTL */ static int __init yama_init(void) { … } DEFINE_LSM(yama) = …;
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