diff options
| -rw-r--r-- | kernel/bpf/helpers.c | 11 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 1 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/prog_tests/task_kfunc.c | 1 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/progs/task_kfunc_common.h | 5 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/progs/task_kfunc_failure.c | 80 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/progs/task_kfunc_success.c | 26 |
6 files changed, 108 insertions, 16 deletions
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 8980f6859443..e71a4a54ce99 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -18,6 +18,7 @@ #include <linux/pid_namespace.h> #include <linux/poison.h> #include <linux/proc_ns.h> +#include <linux/sched/task.h> #include <linux/security.h> #include <linux/btf_ids.h> #include <linux/bpf_mem_alloc.h> @@ -2013,7 +2014,9 @@ __bpf_kfunc struct bpf_rb_node *bpf_rbtree_first(struct bpf_rb_root *root) */ __bpf_kfunc struct task_struct *bpf_task_acquire(struct task_struct *p) { - return get_task_struct(p); + if (refcount_inc_not_zero(&p->rcu_users)) + return p; + return NULL; } /** @@ -2089,7 +2092,7 @@ __bpf_kfunc struct task_struct *bpf_task_kptr_get(struct task_struct **pp) */ __bpf_kfunc void bpf_task_release(struct task_struct *p) { - put_task_struct(p); + put_task_struct_rcu_user(p); } #ifdef CONFIG_CGROUPS @@ -2199,7 +2202,7 @@ __bpf_kfunc struct task_struct *bpf_task_from_pid(s32 pid) rcu_read_lock(); p = find_task_by_pid_ns(pid, &init_pid_ns); if (p) - bpf_task_acquire(p); + p = bpf_task_acquire(p); rcu_read_unlock(); return p; @@ -2371,7 +2374,7 @@ BTF_ID_FLAGS(func, bpf_list_push_front) BTF_ID_FLAGS(func, bpf_list_push_back) BTF_ID_FLAGS(func, bpf_list_pop_front, KF_ACQUIRE | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_list_pop_back, KF_ACQUIRE | KF_RET_NULL) -BTF_ID_FLAGS(func, bpf_task_acquire, KF_ACQUIRE | KF_TRUSTED_ARGS) +BTF_ID_FLAGS(func, bpf_task_acquire, KF_ACQUIRE | KF_RCU | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_task_acquire_not_zero, KF_ACQUIRE | KF_RCU | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_task_kptr_get, KF_ACQUIRE | KF_KPTR_GET | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_task_release, KF_RELEASE) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 52738f9dcb15..92ae4e8ab87b 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4600,6 +4600,7 @@ BTF_SET_START(rcu_protected_types) BTF_ID(struct, prog_test_ref_kfunc) BTF_ID(struct, cgroup) BTF_ID(struct, bpf_cpumask) +BTF_ID(struct, task_struct) BTF_SET_END(rcu_protected_types) static bool rcu_protected_object(const struct btf *btf, u32 btf_id) diff --git a/tools/testing/selftests/bpf/prog_tests/task_kfunc.c b/tools/testing/selftests/bpf/prog_tests/task_kfunc.c index f79fa5bc9a8d..330133ece3f6 100644 --- a/tools/testing/selftests/bpf/prog_tests/task_kfunc.c +++ b/tools/testing/selftests/bpf/prog_tests/task_kfunc.c @@ -78,6 +78,7 @@ static const char * const success_tests[] = { "test_task_from_pid_arg", "test_task_from_pid_current", "test_task_from_pid_invalid", + "task_kfunc_acquire_trusted_walked", }; void test_task_kfunc(void) diff --git a/tools/testing/selftests/bpf/progs/task_kfunc_common.h b/tools/testing/selftests/bpf/progs/task_kfunc_common.h index 4c2a4b0e3a25..bf0d1da9aff8 100644 --- a/tools/testing/selftests/bpf/progs/task_kfunc_common.h +++ b/tools/testing/selftests/bpf/progs/task_kfunc_common.h @@ -24,6 +24,8 @@ struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym; struct task_struct *bpf_task_kptr_get(struct task_struct **pp) __ksym; void bpf_task_release(struct task_struct *p) __ksym; struct task_struct *bpf_task_from_pid(s32 pid) __ksym; +void bpf_rcu_read_lock(void) __ksym; +void bpf_rcu_read_unlock(void) __ksym; static inline struct __tasks_kfunc_map_value *tasks_kfunc_map_value_lookup(struct task_struct *p) { @@ -60,6 +62,9 @@ static inline int tasks_kfunc_map_insert(struct task_struct *p) } acquired = bpf_task_acquire(p); + if (!acquired) + return -ENOENT; + old = bpf_kptr_xchg(&v->task, acquired); if (old) { bpf_task_release(old); diff --git a/tools/testing/selftests/bpf/progs/task_kfunc_failure.c b/tools/testing/selftests/bpf/progs/task_kfunc_failure.c index 2c374a7ffece..63aef547da87 100644 --- a/tools/testing/selftests/bpf/progs/task_kfunc_failure.c +++ b/tools/testing/selftests/bpf/progs/task_kfunc_failure.c @@ -40,6 +40,9 @@ int BPF_PROG(task_kfunc_acquire_untrusted, struct task_struct *task, u64 clone_f /* Can't invoke bpf_task_acquire() on an untrusted pointer. */ acquired = bpf_task_acquire(v->task); + if (!acquired) + return 0; + bpf_task_release(acquired); return 0; @@ -53,38 +56,49 @@ int BPF_PROG(task_kfunc_acquire_fp, struct task_struct *task, u64 clone_flags) /* Can't invoke bpf_task_acquire() on a random frame pointer. */ acquired = bpf_task_acquire((struct task_struct *)&stack_task); + if (!acquired) + return 0; + bpf_task_release(acquired); return 0; } SEC("kretprobe/free_task") -__failure __msg("reg type unsupported for arg#0 function") +__failure __msg("calling kernel function bpf_task_acquire is not allowed") int BPF_PROG(task_kfunc_acquire_unsafe_kretprobe, struct task_struct *task, u64 clone_flags) { struct task_struct *acquired; + /* Can't call bpf_task_acquire() or bpf_task_release() in an untrusted prog. */ acquired = bpf_task_acquire(task); - /* Can't release a bpf_task_acquire()'d task without a NULL check. */ + if (!acquired) + return 0; bpf_task_release(acquired); return 0; } -SEC("tp_btf/task_newtask") -__failure __msg("R1 must be referenced or trusted") -int BPF_PROG(task_kfunc_acquire_trusted_walked, struct task_struct *task, u64 clone_flags) +SEC("kretprobe/free_task") +__failure __msg("calling kernel function bpf_task_acquire is not allowed") +int BPF_PROG(task_kfunc_acquire_unsafe_kretprobe_rcu, struct task_struct *task, u64 clone_flags) { struct task_struct *acquired; - /* Can't invoke bpf_task_acquire() on a trusted pointer obtained from walking a struct. */ - acquired = bpf_task_acquire(task->group_leader); - bpf_task_release(acquired); + bpf_rcu_read_lock(); + if (!task) { + bpf_rcu_read_unlock(); + return 0; + } + /* Can't call bpf_task_acquire() or bpf_task_release() in an untrusted prog. */ + acquired = bpf_task_acquire(task); + if (acquired) + bpf_task_release(acquired); + bpf_rcu_read_unlock(); return 0; } - SEC("tp_btf/task_newtask") __failure __msg("Possibly NULL pointer passed to trusted arg0") int BPF_PROG(task_kfunc_acquire_null, struct task_struct *task, u64 clone_flags) @@ -137,6 +151,8 @@ int BPF_PROG(task_kfunc_get_non_kptr_acquired, struct task_struct *task, u64 clo struct task_struct *kptr, *acquired; acquired = bpf_task_acquire(task); + if (!acquired) + return 0; /* Cannot use bpf_task_kptr_get() on a non-kptr, even if it was acquired. */ kptr = bpf_task_kptr_get(&acquired); @@ -186,6 +202,19 @@ int BPF_PROG(task_kfunc_xchg_unreleased, struct task_struct *task, u64 clone_fla } SEC("tp_btf/task_newtask") +__failure __msg("Possibly NULL pointer passed to trusted arg0") +int BPF_PROG(task_kfunc_acquire_release_no_null_check, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *acquired; + + acquired = bpf_task_acquire(task); + /* Can't invoke bpf_task_release() on an acquired task without a NULL check. */ + bpf_task_release(acquired); + + return 0; +} + +SEC("tp_btf/task_newtask") __failure __msg("Unreleased reference") int BPF_PROG(task_kfunc_get_unreleased, struct task_struct *task, u64 clone_flags) { @@ -256,12 +285,13 @@ int BPF_PROG(task_kfunc_release_null, struct task_struct *task, u64 clone_flags) return -ENOENT; acquired = bpf_task_acquire(task); + if (!acquired) + return -EEXIST; old = bpf_kptr_xchg(&v->task, acquired); /* old cannot be passed to bpf_task_release() without a NULL check. */ bpf_task_release(old); - bpf_task_release(old); return 0; } @@ -298,6 +328,9 @@ int BPF_PROG(task_kfunc_from_lsm_task_free, struct task_struct *task) /* the argument of lsm task_free hook is untrusted. */ acquired = bpf_task_acquire(task); + if (!acquired) + return 0; + bpf_task_release(acquired); return 0; } @@ -337,3 +370,30 @@ int BPF_PROG(task_access_comm4, struct task_struct *task, const char *buf, bool bpf_strncmp(task->comm, 16, "foo"); return 0; } + +SEC("tp_btf/task_newtask") +__failure __msg("R1 must be referenced or trusted") +int BPF_PROG(task_kfunc_release_in_map, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *local; + struct __tasks_kfunc_map_value *v; + + if (tasks_kfunc_map_insert(task)) + return 0; + + v = tasks_kfunc_map_value_lookup(task); + if (!v) + return 0; + + bpf_rcu_read_lock(); + local = v->task; + if (!local) { + bpf_rcu_read_unlock(); + return 0; + } + /* Can't release a kptr that's still stored in a map. */ + bpf_task_release(local); + bpf_rcu_read_unlock(); + + return 0; +} diff --git a/tools/testing/selftests/bpf/progs/task_kfunc_success.c b/tools/testing/selftests/bpf/progs/task_kfunc_success.c index cfa7f12b84e8..a75304a5e860 100644 --- a/tools/testing/selftests/bpf/progs/task_kfunc_success.c +++ b/tools/testing/selftests/bpf/progs/task_kfunc_success.c @@ -47,7 +47,10 @@ static int test_acquire_release(struct task_struct *task) } acquired = bpf_task_acquire(task); - bpf_task_release(acquired); + if (acquired) + bpf_task_release(acquired); + else + err = 6; return 0; } @@ -166,7 +169,10 @@ int BPF_PROG(test_task_current_acquire_release, struct task_struct *task, u64 cl current = bpf_get_current_task_btf(); acquired = bpf_task_acquire(current); - bpf_task_release(acquired); + if (acquired) + bpf_task_release(acquired); + else + err = 1; return 0; } @@ -241,3 +247,19 @@ int BPF_PROG(test_task_from_pid_invalid, struct task_struct *task, u64 clone_fla return 0; } + +SEC("tp_btf/task_newtask") +int BPF_PROG(task_kfunc_acquire_trusted_walked, struct task_struct *task, u64 clone_flags) +{ + struct task_struct *acquired; + + /* task->group_leader is listed as a trusted, non-NULL field of task struct. */ + acquired = bpf_task_acquire(task->group_leader); + if (acquired) + bpf_task_release(acquired); + else + err = 1; + + + return 0; +} |