Require the target task to be a descendant of the container orchestrator/engine.
You would only change the audit container ID from one set or inherited value to another if you were nesting containers. If changing the contid, the container orchestrator/engine must be a descendant and not same orchestrator as the one that set it so it is not possible to change the contid of another orchestrator's container. Since the task_is_descendant() function is used in YAMA and in audit, remove the duplication and pull the function into kernel/core/sched.c Signed-off-by: Richard Guy Briggs <[email protected]> --- include/linux/sched.h | 3 +++ kernel/audit.c | 44 ++++++++++++++++++++++++++++++++++++-------- kernel/sched/core.c | 33 +++++++++++++++++++++++++++++++++ security/yama/yama_lsm.c | 33 --------------------------------- 4 files changed, 72 insertions(+), 41 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index aebe24192b23..009d2cb2e2bf 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2006,4 +2006,7 @@ static inline void rseq_syscall(struct pt_regs *regs) const struct cpumask *sched_trace_rd_span(struct root_domain *rd); +extern int task_is_descendant(struct task_struct *parent, + struct task_struct *child); + #endif diff --git a/kernel/audit.c b/kernel/audit.c index f7a8d3288ca0..ef8e07524c46 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -2575,6 +2575,13 @@ int audit_signal_info(int sig, struct task_struct *t) return audit_signal_info_syscall(t); } +static bool audit_contid_isowner(struct task_struct *tsk) +{ + if (tsk->audit && tsk->audit->cont) + return current == tsk->audit->cont->owner; + return false; +} + /* * audit_set_contid - set current task's audit contid * @task: target task @@ -2603,22 +2610,43 @@ int audit_set_contid(struct task_struct *task, u64 contid) oldcontid = audit_get_contid(task); read_lock(&tasklist_lock); /* Don't allow the contid to be unset */ - if (!audit_contid_valid(contid)) + if (!audit_contid_valid(contid)) { rc = -EINVAL; + goto unlock; + } /* Don't allow the contid to be set to the same value again */ - else if (contid == oldcontid) { + if (contid == oldcontid) { rc = -EADDRINUSE; + goto unlock; + } /* if we don't have caps, reject */ - else if (!capable(CAP_AUDIT_CONTROL)) + if (!capable(CAP_AUDIT_CONTROL)) { rc = -EPERM; - /* if task has children or is not single-threaded, deny */ - else if (!list_empty(&task->children)) + goto unlock; + } + /* if task has children, deny */ + if (!list_empty(&task->children)) { rc = -EBUSY; - else if (!(thread_group_leader(task) && thread_group_empty(task))) + goto unlock; + } + /* if task is not single-threaded, deny */ + if (!(thread_group_leader(task) && thread_group_empty(task))) { rc = -EALREADY; - /* if contid is already set, deny */ - else if (audit_contid_set(task)) + goto unlock; + } + /* if task is not descendant, block */ + if (task == current) { + rc = -EBADSLT; + goto unlock; + } + if (!task_is_descendant(current, task)) { + rc = -EXDEV; + goto unlock; + } + /* only allow contid setting again if nesting */ + if (audit_contid_set(task) && audit_contid_isowner(task)) rc = -ECHILD; +unlock: read_unlock(&tasklist_lock); if (!rc) { struct audit_contobj *oldcont = _audit_contobj(task); diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 90e4b00ace89..7d8145285eb9 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7916,6 +7916,39 @@ void dump_cpu_task(int cpu) } /* + * 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. + */ +int task_is_descendant(struct task_struct *parent, + struct task_struct *child) +{ + int rc = 0; + struct task_struct *walker = child; + + if (!parent || !child) + return 0; + + rcu_read_lock(); + if (!thread_group_leader(parent)) + parent = rcu_dereference(parent->group_leader); + while (walker->pid > 0) { + if (!thread_group_leader(walker)) + walker = rcu_dereference(walker->group_leader); + if (walker == parent) { + rc = 1; + break; + } + walker = rcu_dereference(walker->real_parent); + } + rcu_read_unlock(); + + return rc; +} + +/* * Nice levels are multiplicative, with a gentle 10% change for every * nice level changed. I.e. when a CPU-bound task goes from nice 0 to * nice 1, it will get ~10% less CPU time than another CPU-bound task diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c index 94dc346370b1..25eae205eae8 100644 --- a/security/yama/yama_lsm.c +++ b/security/yama/yama_lsm.c @@ -263,39 +263,6 @@ static int yama_task_prctl(int option, unsigned long arg2, unsigned long arg3, } /** - * 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) -{ - int rc = 0; - struct task_struct *walker = child; - - if (!parent || !child) - return 0; - - rcu_read_lock(); - if (!thread_group_leader(parent)) - parent = rcu_dereference(parent->group_leader); - while (walker->pid > 0) { - if (!thread_group_leader(walker)) - walker = rcu_dereference(walker->group_leader); - if (walker == parent) { - rc = 1; - break; - } - walker = rcu_dereference(walker->real_parent); - } - rcu_read_unlock(); - - return rc; -} - -/** * 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 -- 1.8.3.1 -- Linux-audit mailing list [email protected] https://www.redhat.com/mailman/listinfo/linux-audit
