diff options
Diffstat (limited to 'security/yama/yama_lsm.c')
| -rw-r--r-- | security/yama/yama_lsm.c | 100 |
1 files changed, 71 insertions, 29 deletions
diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c index b4c29848b49..23414b93771 100644 --- a/security/yama/yama_lsm.c +++ b/security/yama/yama_lsm.c @@ -17,6 +17,7 @@ #include <linux/ptrace.h> #include <linux/prctl.h> #include <linux/ratelimit.h> +#include <linux/workqueue.h> #define YAMA_SCOPE_DISABLED 0 #define YAMA_SCOPE_RELATIONAL 1 @@ -29,12 +30,37 @@ static int ptrace_scope = YAMA_SCOPE_RELATIONAL; struct ptrace_relation { struct task_struct *tracer; struct task_struct *tracee; + bool invalid; struct list_head node; + struct rcu_head rcu; }; 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); + +/** + * yama_relation_cleanup - remove invalid entries from the relation list + * + */ +static void yama_relation_cleanup(struct work_struct *work) +{ + struct ptrace_relation *relation; + + spin_lock(&ptracer_relations_lock); + rcu_read_lock(); + list_for_each_entry_rcu(relation, &ptracer_relations, node) { + if (relation->invalid) { + list_del_rcu(&relation->node); + kfree_rcu(relation, rcu); + } + } + rcu_read_unlock(); + spin_unlock(&ptracer_relations_lock); +} + /** * yama_ptracer_add - add/replace an exception for this tracer/tracee pair * @tracer: the task_struct of the process doing the ptrace @@ -48,32 +74,34 @@ static DEFINE_SPINLOCK(ptracer_relations_lock); static int yama_ptracer_add(struct task_struct *tracer, struct task_struct *tracee) { - int rc = 0; - struct ptrace_relation *added; - struct ptrace_relation *entry, *relation = NULL; + struct ptrace_relation *relation, *added; added = kmalloc(sizeof(*added), GFP_KERNEL); if (!added) return -ENOMEM; - spin_lock_bh(&ptracer_relations_lock); - list_for_each_entry(entry, &ptracer_relations, node) - if (entry->tracee == tracee) { - relation = entry; - break; + added->tracee = tracee; + added->tracer = tracer; + added->invalid = false; + + spin_lock(&ptracer_relations_lock); + rcu_read_lock(); + list_for_each_entry_rcu(relation, &ptracer_relations, node) { + if (relation->invalid) + continue; + if (relation->tracee == tracee) { + list_replace_rcu(&relation->node, &added->node); + kfree_rcu(relation, rcu); + goto out; } - if (!relation) { - relation = added; - relation->tracee = tracee; - list_add(&relation->node, &ptracer_relations); } - relation->tracer = tracer; - spin_unlock_bh(&ptracer_relations_lock); - if (added != relation) - kfree(added); + list_add_rcu(&added->node, &ptracer_relations); - return rc; +out: + rcu_read_unlock(); + spin_unlock(&ptracer_relations_lock); + return 0; } /** @@ -84,16 +112,23 @@ static int yama_ptracer_add(struct task_struct *tracer, static void yama_ptracer_del(struct task_struct *tracer, struct task_struct *tracee) { - struct ptrace_relation *relation, *safe; + struct ptrace_relation *relation; + bool marked = false; - spin_lock_bh(&ptracer_relations_lock); - list_for_each_entry_safe(relation, safe, &ptracer_relations, node) + rcu_read_lock(); + list_for_each_entry_rcu(relation, &ptracer_relations, node) { + if (relation->invalid) + continue; if (relation->tracee == tracee || (tracer && relation->tracer == tracer)) { - list_del(&relation->node); - kfree(relation); + relation->invalid = true; + marked = true; } - spin_unlock_bh(&ptracer_relations_lock); + } + rcu_read_unlock(); + + if (marked) + schedule_work(&yama_relation_work); } /** @@ -217,21 +252,22 @@ static int ptracer_exception_found(struct task_struct *tracer, struct task_struct *parent = NULL; bool found = false; - spin_lock_bh(&ptracer_relations_lock); rcu_read_lock(); if (!thread_group_leader(tracee)) tracee = rcu_dereference(tracee->group_leader); - list_for_each_entry(relation, &ptracer_relations, node) + list_for_each_entry_rcu(relation, &ptracer_relations, node) { + if (relation->invalid) + continue; if (relation->tracee == tracee) { parent = relation->tracer; found = true; break; } + } if (found && (parent == NULL || task_is_descendant(parent, tracer))) rc = 1; rcu_read_unlock(); - spin_unlock_bh(&ptracer_relations_lock); return rc; } @@ -262,14 +298,18 @@ int yama_ptrace_access_check(struct task_struct *child, /* No additional restrictions. */ break; case YAMA_SCOPE_RELATIONAL: + rcu_read_lock(); if (!task_is_descendant(current, child) && !ptracer_exception_found(current, child) && - !ns_capable(task_user_ns(child), CAP_SYS_PTRACE)) + !ns_capable(__task_cred(child)->user_ns, CAP_SYS_PTRACE)) rc = -EPERM; + rcu_read_unlock(); break; case YAMA_SCOPE_CAPABILITY: - if (!ns_capable(task_user_ns(child), CAP_SYS_PTRACE)) + rcu_read_lock(); + if (!ns_capable(__task_cred(child)->user_ns, CAP_SYS_PTRACE)) rc = -EPERM; + rcu_read_unlock(); break; case YAMA_SCOPE_NO_ATTACH: default: @@ -307,8 +347,10 @@ int yama_ptrace_traceme(struct task_struct *parent) /* Only disallow PTRACE_TRACEME on more aggressive settings. */ switch (ptrace_scope) { case YAMA_SCOPE_CAPABILITY: - if (!ns_capable(task_user_ns(parent), CAP_SYS_PTRACE)) + rcu_read_lock(); + if (!ns_capable(__task_cred(parent)->user_ns, CAP_SYS_PTRACE)) rc = -EPERM; + rcu_read_unlock(); break; case YAMA_SCOPE_NO_ATTACH: rc = -EPERM; |