diff --git a/include/linux/bpf.h b/include/linux/bpf.h index f3f50e29d639..15164787ce7f 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -968,6 +968,7 @@ struct bpf_insn_access_aux { struct { struct btf *btf; u32 btf_id; + u32 ref_obj_id; }; }; struct bpf_verifier_log *log; /* for verbose logs */ @@ -1481,6 +1482,8 @@ struct bpf_ctx_arg_aux { enum bpf_reg_type reg_type; struct btf *btf; u32 btf_id; + u32 ref_obj_id; + bool refcounted; }; struct btf_mod_pair { @@ -1507,7 +1510,7 @@ struct bpf_prog_aux { u32 max_rdonly_access; u32 max_rdwr_access; struct btf *attach_btf; - const struct bpf_ctx_arg_aux *ctx_arg_info; + struct bpf_ctx_arg_aux *ctx_arg_info; void __percpu *priv_stack_ptr; struct mutex dst_mutex; /* protects dst_* pointers below, *after* prog becomes visible */ struct bpf_prog *dst_prog; @@ -1945,6 +1948,9 @@ static inline void bpf_struct_ops_desc_release(struct bpf_struct_ops_desc *st_op #endif +int bpf_prog_ctx_arg_info_init(struct bpf_prog *prog, + const struct bpf_ctx_arg_aux *info, u32 cnt); + #if defined(CONFIG_CGROUP_BPF) && defined(CONFIG_BPF_LSM) int bpf_trampoline_link_cgroup_shim(struct bpf_prog *prog, int cgroup_atype); @@ -2546,7 +2552,7 @@ struct bpf_iter__bpf_map_elem { int bpf_iter_reg_target(const struct bpf_iter_reg *reg_info); void bpf_iter_unreg_target(const struct bpf_iter_reg *reg_info); -bool bpf_iter_prog_supported(struct bpf_prog *prog); +int bpf_iter_prog_supported(struct bpf_prog *prog); const struct bpf_func_proto * bpf_iter_get_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog); int bpf_iter_link_attach(const union bpf_attr *attr, bpfptr_t uattr, struct bpf_prog *prog); diff --git a/kernel/bpf/bpf_iter.c b/kernel/bpf/bpf_iter.c index 106735145948..380e9a7cac75 100644 --- a/kernel/bpf/bpf_iter.c +++ b/kernel/bpf/bpf_iter.c @@ -335,7 +335,7 @@ static void cache_btf_id(struct bpf_iter_target_info *tinfo, tinfo->btf_id = prog->aux->attach_btf_id; } -bool bpf_iter_prog_supported(struct bpf_prog *prog) +int bpf_iter_prog_supported(struct bpf_prog *prog) { const char *attach_fname = prog->aux->attach_func_name; struct bpf_iter_target_info *tinfo = NULL, *iter; @@ -344,7 +344,7 @@ bool bpf_iter_prog_supported(struct bpf_prog *prog) int prefix_len = strlen(prefix); if (strncmp(attach_fname, prefix, prefix_len)) - return false; + return -EINVAL; mutex_lock(&targets_mutex); list_for_each_entry(iter, &targets, list) { @@ -360,12 +360,11 @@ bool bpf_iter_prog_supported(struct bpf_prog *prog) } mutex_unlock(&targets_mutex); - if (tinfo) { - prog->aux->ctx_arg_info_size = tinfo->reg_info->ctx_arg_info_size; - prog->aux->ctx_arg_info = tinfo->reg_info->ctx_arg_info; - } + if (!tinfo) + return -EINVAL; - return tinfo != NULL; + return bpf_prog_ctx_arg_info_init(prog, tinfo->reg_info->ctx_arg_info, + tinfo->reg_info->ctx_arg_info_size); } const struct bpf_func_proto * diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c index 9b7f3b9c5262..db13ee70d94d 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -146,6 +146,7 @@ void bpf_struct_ops_image_free(void *image) } #define MAYBE_NULL_SUFFIX "__nullable" +#define REFCOUNTED_SUFFIX "__ref" /* Prepare argument info for every nullable argument of a member of a * struct_ops type. @@ -174,11 +175,13 @@ static int prepare_arg_info(struct btf *btf, struct bpf_struct_ops_arg_info *arg_info) { const struct btf_type *stub_func_proto, *pointed_type; + bool is_nullable = false, is_refcounted = false; const struct btf_param *stub_args, *args; struct bpf_ctx_arg_aux *info, *info_buf; u32 nargs, arg_no, info_cnt = 0; char ksym[KSYM_SYMBOL_LEN]; const char *stub_fname; + const char *suffix; s32 stub_func_id; u32 arg_btf_id; int offset; @@ -223,10 +226,18 @@ static int prepare_arg_info(struct btf *btf, info = info_buf; for (arg_no = 0; arg_no < nargs; arg_no++) { /* Skip arguments that is not suffixed with - * "__nullable". + * "__nullable or __ref". */ - if (!btf_param_match_suffix(btf, &stub_args[arg_no], - MAYBE_NULL_SUFFIX)) + is_nullable = btf_param_match_suffix(btf, &stub_args[arg_no], + MAYBE_NULL_SUFFIX); + is_refcounted = btf_param_match_suffix(btf, &stub_args[arg_no], + REFCOUNTED_SUFFIX); + + if (is_nullable) + suffix = MAYBE_NULL_SUFFIX; + else if (is_refcounted) + suffix = REFCOUNTED_SUFFIX; + else continue; /* Should be a pointer to struct */ @@ -236,7 +247,7 @@ static int prepare_arg_info(struct btf *btf, if (!pointed_type || !btf_type_is_struct(pointed_type)) { pr_warn("stub function %s has %s tagging to an unsupported type\n", - stub_fname, MAYBE_NULL_SUFFIX); + stub_fname, suffix); goto err_out; } @@ -254,11 +265,15 @@ static int prepare_arg_info(struct btf *btf, } /* Fill the information of the new argument */ - info->reg_type = - PTR_TRUSTED | PTR_TO_BTF_ID | PTR_MAYBE_NULL; info->btf_id = arg_btf_id; info->btf = btf; info->offset = offset; + if (is_nullable) { + info->reg_type = PTR_TRUSTED | PTR_TO_BTF_ID | PTR_MAYBE_NULL; + } else if (is_refcounted) { + info->reg_type = PTR_TRUSTED | PTR_TO_BTF_ID; + info->refcounted = true; + } info++; info_cnt++; @@ -375,7 +390,7 @@ int bpf_struct_ops_desc_init(struct bpf_struct_ops_desc *st_ops_desc, st_ops_desc->value_type = btf_type_by_id(btf, value_id); for_each_member(i, t, member) { - const struct btf_type *func_proto; + const struct btf_type *func_proto, *ret_type; void **stub_func_addr; u32 moff; @@ -412,6 +427,16 @@ int bpf_struct_ops_desc_init(struct bpf_struct_ops_desc *st_ops_desc, if (!func_proto || bpf_struct_ops_supported(st_ops, moff)) continue; + if (func_proto->type) { + ret_type = btf_type_resolve_ptr(btf, func_proto->type, NULL); + if (ret_type && !__btf_type_is_struct(ret_type)) { + pr_warn("func ptr %s in struct %s returns non-struct pointer, which is not supported\n", + mname, st_ops->name); + err = -EOPNOTSUPP; + goto errout; + } + } + if (btf_distill_func_proto(log, btf, func_proto, mname, &st_ops->func_models[i])) { diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index f8335bdc8bf8..69f5752e880b 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6774,6 +6774,7 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, info->reg_type = ctx_arg_info->reg_type; info->btf = ctx_arg_info->btf ? : btf_vmlinux; info->btf_id = ctx_arg_info->btf_id; + info->ref_obj_id = ctx_arg_info->ref_obj_id; return true; } } diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index c420edbfb7c8..4b89a5df8ebc 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2313,6 +2313,7 @@ static void __bpf_prog_put_noref(struct bpf_prog *prog, bool deferred) kvfree(prog->aux->jited_linfo); kvfree(prog->aux->linfo); kfree(prog->aux->kfunc_tab); + kfree(prog->aux->ctx_arg_info); if (prog->aux->attach_btf) btf_put(prog->aux->attach_btf); diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 3c286ec9e841..e7bc74171c99 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1543,6 +1543,17 @@ static void release_reference_state(struct bpf_verifier_state *state, int idx) return; } +static bool find_reference_state(struct bpf_verifier_state *state, int ptr_id) +{ + int i; + + for (i = 0; i < state->acquired_refs; i++) + if (state->refs[i].id == ptr_id) + return true; + + return false; +} + static int release_lock_state(struct bpf_verifier_state *state, int type, int id, void *ptr) { int i; @@ -5981,7 +5992,8 @@ static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off, /* check access to 'struct bpf_context' fields. Supports fixed offsets only */ static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size, enum bpf_access_type t, enum bpf_reg_type *reg_type, - struct btf **btf, u32 *btf_id, bool *is_retval, bool is_ldsx) + struct btf **btf, u32 *btf_id, bool *is_retval, bool is_ldsx, + u32 *ref_obj_id) { struct bpf_insn_access_aux info = { .reg_type = *reg_type, @@ -6003,8 +6015,16 @@ static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, *is_retval = info.is_retval; if (base_type(*reg_type) == PTR_TO_BTF_ID) { + if (info.ref_obj_id && + !find_reference_state(env->cur_state, info.ref_obj_id)) { + verbose(env, "invalid bpf_context access off=%d. Reference may already be released\n", + off); + return -EACCES; + } + *btf = info.btf; *btf_id = info.btf_id; + *ref_obj_id = info.ref_obj_id; } else { env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size; } @@ -7367,7 +7387,7 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn struct bpf_retval_range range; enum bpf_reg_type reg_type = SCALAR_VALUE; struct btf *btf = NULL; - u32 btf_id = 0; + u32 btf_id = 0, ref_obj_id = 0; if (t == BPF_WRITE && value_regno >= 0 && is_pointer_value(env, value_regno)) { @@ -7380,7 +7400,7 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn return err; err = check_ctx_access(env, insn_idx, off, size, t, ®_type, &btf, - &btf_id, &is_retval, is_ldsx); + &btf_id, &is_retval, is_ldsx, &ref_obj_id); if (err) verbose_linfo(env, insn_idx, "; "); if (!err && t == BPF_READ && value_regno >= 0) { @@ -7411,6 +7431,7 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn if (base_type(reg_type) == PTR_TO_BTF_ID) { regs[value_regno].btf = btf; regs[value_regno].btf_id = btf_id; + regs[value_regno].ref_obj_id = ref_obj_id; } } regs[value_regno].type = reg_type; @@ -10737,6 +10758,8 @@ record_func_key(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta, static int check_reference_leak(struct bpf_verifier_env *env, bool exception_exit) { struct bpf_verifier_state *state = env->cur_state; + enum bpf_prog_type type = resolve_prog_type(env->prog); + struct bpf_reg_state *reg = reg_state(env, BPF_REG_0); bool refs_lingering = false; int i; @@ -10746,6 +10769,12 @@ static int check_reference_leak(struct bpf_verifier_env *env, bool exception_exi for (i = 0; i < state->acquired_refs; i++) { if (state->refs[i].type != REF_TYPE_PTR) continue; + /* Allow struct_ops programs to return a referenced kptr back to + * kernel. Type checks are performed later in check_return_code. + */ + if (type == BPF_PROG_TYPE_STRUCT_OPS && !exception_exit && + reg->ref_obj_id == state->refs[i].id) + continue; verbose(env, "Unreleased reference id=%d alloc_insn=%d\n", state->refs[i].id, state->refs[i].insn_idx); refs_lingering = true; @@ -16397,13 +16426,14 @@ static int check_return_code(struct bpf_verifier_env *env, int regno, const char const char *exit_ctx = "At program exit"; struct tnum enforce_attach_type_range = tnum_unknown; const struct bpf_prog *prog = env->prog; - struct bpf_reg_state *reg; + struct bpf_reg_state *reg = reg_state(env, regno); struct bpf_retval_range range = retval_range(0, 1); enum bpf_prog_type prog_type = resolve_prog_type(env->prog); int err; struct bpf_func_state *frame = env->cur_state->frame[0]; const bool is_subprog = frame->subprogno; bool return_32bit = false; + const struct btf_type *reg_type, *ret_type = NULL; /* LSM and struct_ops func-ptr's return type could be "void" */ if (!is_subprog || frame->in_exception_callback_fn) { @@ -16412,10 +16442,26 @@ static int check_return_code(struct bpf_verifier_env *env, int regno, const char if (prog->expected_attach_type == BPF_LSM_CGROUP) /* See below, can be 0 or 0-1 depending on hook. */ break; - fallthrough; + if (!prog->aux->attach_func_proto->type) + return 0; + break; case BPF_PROG_TYPE_STRUCT_OPS: if (!prog->aux->attach_func_proto->type) return 0; + + if (frame->in_exception_callback_fn) + break; + + /* Allow a struct_ops program to return a referenced kptr if it + * matches the operator's return type and is in its unmodified + * form. A scalar zero (i.e., a null pointer) is also allowed. + */ + reg_type = reg->btf ? btf_type_by_id(reg->btf, reg->btf_id) : NULL; + ret_type = btf_type_resolve_ptr(prog->aux->attach_btf, + prog->aux->attach_func_proto->type, + NULL); + if (ret_type && ret_type == reg_type && reg->ref_obj_id) + return __check_ptr_off_reg(env, reg, regno, false); break; default: break; @@ -16437,8 +16483,6 @@ static int check_return_code(struct bpf_verifier_env *env, int regno, const char return -EACCES; } - reg = cur_regs(env) + regno; - if (frame->in_async_callback_fn) { /* enforce return zero from async callbacks like timer */ exit_ctx = "At async callback return"; @@ -16537,6 +16581,11 @@ static int check_return_code(struct bpf_verifier_env *env, int regno, const char case BPF_PROG_TYPE_NETFILTER: range = retval_range(NF_DROP, NF_ACCEPT); break; + case BPF_PROG_TYPE_STRUCT_OPS: + if (!ret_type) + return 0; + range = retval_range(0, 0); + break; case BPF_PROG_TYPE_EXT: /* freplace program can return anything as its return value * depends on the to-be-replaced kernel func or bpf program. @@ -22176,6 +22225,7 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog) { bool pop_log = !(env->log.level & BPF_LOG_LEVEL2); struct bpf_subprog_info *sub = subprog_info(env, subprog); + struct bpf_prog_aux *aux = env->prog->aux; struct bpf_verifier_state *state; struct bpf_reg_state *regs; int ret, i; @@ -22283,6 +22333,13 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog) mark_reg_known_zero(env, regs, BPF_REG_1); } + /* Acquire references for struct_ops program arguments tagged with "__ref" */ + if (!subprog && env->prog->type == BPF_PROG_TYPE_STRUCT_OPS) { + for (i = 0; i < aux->ctx_arg_info_size; i++) + aux->ctx_arg_info[i].ref_obj_id = aux->ctx_arg_info[i].refcounted ? + acquire_reference(env, 0) : 0; + } + ret = do_check(env); out: /* check for NULL is necessary, since cur_state can be freed inside @@ -22405,6 +22462,15 @@ static void print_verification_stats(struct bpf_verifier_env *env) env->peak_states, env->longest_mark_read_walk); } +int bpf_prog_ctx_arg_info_init(struct bpf_prog *prog, + const struct bpf_ctx_arg_aux *info, u32 cnt) +{ + prog->aux->ctx_arg_info = kmemdup_array(info, cnt, sizeof(*info), GFP_KERNEL); + prog->aux->ctx_arg_info_size = cnt; + + return prog->aux->ctx_arg_info ? 0 : -ENOMEM; +} + static int check_struct_ops_btf_id(struct bpf_verifier_env *env) { const struct btf_type *t, *func_proto; @@ -22485,17 +22551,12 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env) return -EACCES; } - /* btf_ctx_access() used this to provide argument type info */ - prog->aux->ctx_arg_info = - st_ops_desc->arg_info[member_idx].info; - prog->aux->ctx_arg_info_size = - st_ops_desc->arg_info[member_idx].cnt; - prog->aux->attach_func_proto = func_proto; prog->aux->attach_func_name = mname; env->ops = st_ops->verifier_ops; - return 0; + return bpf_prog_ctx_arg_info_init(prog, st_ops_desc->arg_info[member_idx].info, + st_ops_desc->arg_info[member_idx].cnt); } #define SECURITY_PREFIX "security_" @@ -22945,9 +23006,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) prog->aux->attach_btf_trace = true; return 0; } else if (prog->expected_attach_type == BPF_TRACE_ITER) { - if (!bpf_iter_prog_supported(prog)) - return -EINVAL; - return 0; + return bpf_iter_prog_supported(prog); } if (prog->type == BPF_PROG_TYPE_LSM) { diff --git a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_kptr_return.c b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_kptr_return.c new file mode 100644 index 000000000000..467cc72a3588 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_kptr_return.c @@ -0,0 +1,16 @@ +#include + +#include "struct_ops_kptr_return.skel.h" +#include "struct_ops_kptr_return_fail__wrong_type.skel.h" +#include "struct_ops_kptr_return_fail__invalid_scalar.skel.h" +#include "struct_ops_kptr_return_fail__nonzero_offset.skel.h" +#include "struct_ops_kptr_return_fail__local_kptr.skel.h" + +void test_struct_ops_kptr_return(void) +{ + RUN_TESTS(struct_ops_kptr_return); + RUN_TESTS(struct_ops_kptr_return_fail__wrong_type); + RUN_TESTS(struct_ops_kptr_return_fail__invalid_scalar); + RUN_TESTS(struct_ops_kptr_return_fail__nonzero_offset); + RUN_TESTS(struct_ops_kptr_return_fail__local_kptr); +} diff --git a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_refcounted.c b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_refcounted.c new file mode 100644 index 000000000000..e290a2f6db95 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_refcounted.c @@ -0,0 +1,12 @@ +#include + +#include "struct_ops_refcounted.skel.h" +#include "struct_ops_refcounted_fail__ref_leak.skel.h" +#include "struct_ops_refcounted_fail__global_subprog.skel.h" + +void test_struct_ops_refcounted(void) +{ + RUN_TESTS(struct_ops_refcounted); + RUN_TESTS(struct_ops_refcounted_fail__ref_leak); + RUN_TESTS(struct_ops_refcounted_fail__global_subprog); +} diff --git a/tools/testing/selftests/bpf/progs/struct_ops_kptr_return.c b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return.c new file mode 100644 index 000000000000..36386b3c23a1 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return.c @@ -0,0 +1,30 @@ +#include +#include +#include "../test_kmods/bpf_testmod.h" +#include "bpf_misc.h" + +char _license[] SEC("license") = "GPL"; + +void bpf_task_release(struct task_struct *p) __ksym; + +/* This test struct_ops BPF programs returning referenced kptr. The verifier should + * allow a referenced kptr or a NULL pointer to be returned. A referenced kptr to task + * here is acquried automatically as the task argument is tagged with "__ref". + */ +SEC("struct_ops/test_return_ref_kptr") +struct task_struct *BPF_PROG(kptr_return, int dummy, + struct task_struct *task, struct cgroup *cgrp) +{ + if (dummy % 2) { + bpf_task_release(task); + return NULL; + } + return task; +} + +SEC(".struct_ops.link") +struct bpf_testmod_ops testmod_kptr_return = { + .test_return_ref_kptr = (void *)kptr_return, +}; + + diff --git a/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__invalid_scalar.c b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__invalid_scalar.c new file mode 100644 index 000000000000..caeea158ef69 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__invalid_scalar.c @@ -0,0 +1,26 @@ +#include +#include +#include "../test_kmods/bpf_testmod.h" +#include "bpf_misc.h" + +char _license[] SEC("license") = "GPL"; + +struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym; +void bpf_task_release(struct task_struct *p) __ksym; + +/* This test struct_ops BPF programs returning referenced kptr. The verifier should + * reject programs returning a non-zero scalar value. + */ +SEC("struct_ops/test_return_ref_kptr") +__failure __msg("At program exit the register R0 has smin=1 smax=1 should have been in [0, 0]") +struct task_struct *BPF_PROG(kptr_return_fail__invalid_scalar, int dummy, + struct task_struct *task, struct cgroup *cgrp) +{ + bpf_task_release(task); + return (struct task_struct *)1; +} + +SEC(".struct_ops.link") +struct bpf_testmod_ops testmod_kptr_return = { + .test_return_ref_kptr = (void *)kptr_return_fail__invalid_scalar, +}; diff --git a/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__local_kptr.c b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__local_kptr.c new file mode 100644 index 000000000000..b8b4f05c3d7f --- /dev/null +++ b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__local_kptr.c @@ -0,0 +1,34 @@ +#include +#include +#include "../test_kmods/bpf_testmod.h" +#include "bpf_experimental.h" +#include "bpf_misc.h" + +char _license[] SEC("license") = "GPL"; + +struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym; +void bpf_task_release(struct task_struct *p) __ksym; + +/* This test struct_ops BPF programs returning referenced kptr. The verifier should + * reject programs returning a local kptr. + */ +SEC("struct_ops/test_return_ref_kptr") +__failure __msg("At program exit the register R0 is not a known value (ptr_or_null_)") +struct task_struct *BPF_PROG(kptr_return_fail__local_kptr, int dummy, + struct task_struct *task, struct cgroup *cgrp) +{ + struct task_struct *t; + + bpf_task_release(task); + + t = bpf_obj_new(typeof(*task)); + if (!t) + return NULL; + + return t; +} + +SEC(".struct_ops.link") +struct bpf_testmod_ops testmod_kptr_return = { + .test_return_ref_kptr = (void *)kptr_return_fail__local_kptr, +}; diff --git a/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__nonzero_offset.c b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__nonzero_offset.c new file mode 100644 index 000000000000..7ddeb28c2329 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__nonzero_offset.c @@ -0,0 +1,25 @@ +#include +#include +#include "../test_kmods/bpf_testmod.h" +#include "bpf_misc.h" + +char _license[] SEC("license") = "GPL"; + +struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym; +void bpf_task_release(struct task_struct *p) __ksym; + +/* This test struct_ops BPF programs returning referenced kptr. The verifier should + * reject programs returning a modified referenced kptr. + */ +SEC("struct_ops/test_return_ref_kptr") +__failure __msg("dereference of modified trusted_ptr_ ptr R0 off={{[0-9]+}} disallowed") +struct task_struct *BPF_PROG(kptr_return_fail__nonzero_offset, int dummy, + struct task_struct *task, struct cgroup *cgrp) +{ + return (struct task_struct *)&task->jobctl; +} + +SEC(".struct_ops.link") +struct bpf_testmod_ops testmod_kptr_return = { + .test_return_ref_kptr = (void *)kptr_return_fail__nonzero_offset, +}; diff --git a/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__wrong_type.c b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__wrong_type.c new file mode 100644 index 000000000000..6a2dd5367802 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__wrong_type.c @@ -0,0 +1,30 @@ +#include +#include +#include "../test_kmods/bpf_testmod.h" +#include "bpf_misc.h" + +char _license[] SEC("license") = "GPL"; + +struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym; +void bpf_task_release(struct task_struct *p) __ksym; + +/* This test struct_ops BPF programs returning referenced kptr. The verifier should + * reject programs returning a referenced kptr of the wrong type. + */ +SEC("struct_ops/test_return_ref_kptr") +__failure __msg("At program exit the register R0 is not a known value (ptr_or_null_)") +struct task_struct *BPF_PROG(kptr_return_fail__wrong_type, int dummy, + struct task_struct *task, struct cgroup *cgrp) +{ + struct task_struct *ret; + + ret = (struct task_struct *)bpf_cgroup_acquire(cgrp); + bpf_task_release(task); + + return ret; +} + +SEC(".struct_ops.link") +struct bpf_testmod_ops testmod_kptr_return = { + .test_return_ref_kptr = (void *)kptr_return_fail__wrong_type, +}; diff --git a/tools/testing/selftests/bpf/progs/struct_ops_refcounted.c b/tools/testing/selftests/bpf/progs/struct_ops_refcounted.c new file mode 100644 index 000000000000..76dcb6089d7f --- /dev/null +++ b/tools/testing/selftests/bpf/progs/struct_ops_refcounted.c @@ -0,0 +1,31 @@ +#include +#include +#include "../test_kmods/bpf_testmod.h" +#include "bpf_misc.h" + +char _license[] SEC("license") = "GPL"; + +__attribute__((nomerge)) extern void bpf_task_release(struct task_struct *p) __ksym; + +/* This is a test BPF program that uses struct_ops to access a referenced + * kptr argument. This is a test for the verifier to ensure that it + * 1) recongnizes the task as a referenced object (i.e., ref_obj_id > 0), and + * 2) the same reference can be acquired from multiple paths as long as it + * has not been released. + */ +SEC("struct_ops/test_refcounted") +int BPF_PROG(refcounted, int dummy, struct task_struct *task) +{ + if (dummy == 1) + bpf_task_release(task); + else + bpf_task_release(task); + return 0; +} + +SEC(".struct_ops.link") +struct bpf_testmod_ops testmod_refcounted = { + .test_refcounted = (void *)refcounted, +}; + + diff --git a/tools/testing/selftests/bpf/progs/struct_ops_refcounted_fail__global_subprog.c b/tools/testing/selftests/bpf/progs/struct_ops_refcounted_fail__global_subprog.c new file mode 100644 index 000000000000..ae074aa62852 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/struct_ops_refcounted_fail__global_subprog.c @@ -0,0 +1,39 @@ +#include +#include +#include "../test_kmods/bpf_testmod.h" +#include "bpf_misc.h" + +char _license[] SEC("license") = "GPL"; + +extern void bpf_task_release(struct task_struct *p) __ksym; + +__noinline int subprog_release(__u64 *ctx __arg_ctx) +{ + struct task_struct *task = (struct task_struct *)ctx[1]; + int dummy = (int)ctx[0]; + + bpf_task_release(task); + + return dummy + 1; +} + +/* Test that the verifier rejects a program that contains a global + * subprogram with referenced kptr arguments + */ +SEC("struct_ops/test_refcounted") +__failure __log_level(2) +__msg("Validating subprog_release() func#1...") +__msg("invalid bpf_context access off=8. Reference may already be released") +int refcounted_fail__global_subprog(unsigned long long *ctx) +{ + struct task_struct *task = (struct task_struct *)ctx[1]; + + bpf_task_release(task); + + return subprog_release(ctx); +} + +SEC(".struct_ops.link") +struct bpf_testmod_ops testmod_ref_acquire = { + .test_refcounted = (void *)refcounted_fail__global_subprog, +}; diff --git a/tools/testing/selftests/bpf/progs/struct_ops_refcounted_fail__ref_leak.c b/tools/testing/selftests/bpf/progs/struct_ops_refcounted_fail__ref_leak.c new file mode 100644 index 000000000000..e945b1a04294 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/struct_ops_refcounted_fail__ref_leak.c @@ -0,0 +1,22 @@ +#include +#include +#include "../test_kmods/bpf_testmod.h" +#include "bpf_misc.h" + +char _license[] SEC("license") = "GPL"; + +/* Test that the verifier rejects a program that acquires a referenced + * kptr through context without releasing the reference + */ +SEC("struct_ops/test_refcounted") +__failure __msg("Unreleased reference id=1 alloc_insn=0") +int BPF_PROG(refcounted_fail__ref_leak, int dummy, + struct task_struct *task) +{ + return 0; +} + +SEC(".struct_ops.link") +struct bpf_testmod_ops testmod_ref_acquire = { + .test_refcounted = (void *)refcounted_fail__ref_leak, +}; diff --git a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c index cc9dde507aba..89dc502de9d4 100644 --- a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c +++ b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c @@ -1176,10 +1176,25 @@ static int bpf_testmod_ops__test_maybe_null(int dummy, return 0; } +static int bpf_testmod_ops__test_refcounted(int dummy, + struct task_struct *task__ref) +{ + return 0; +} + +static struct task_struct * +bpf_testmod_ops__test_return_ref_kptr(int dummy, struct task_struct *task__ref, + struct cgroup *cgrp) +{ + return NULL; +} + static struct bpf_testmod_ops __bpf_testmod_ops = { .test_1 = bpf_testmod_test_1, .test_2 = bpf_testmod_test_2, .test_maybe_null = bpf_testmod_ops__test_maybe_null, + .test_refcounted = bpf_testmod_ops__test_refcounted, + .test_return_ref_kptr = bpf_testmod_ops__test_return_ref_kptr, }; struct bpf_struct_ops bpf_bpf_testmod_ops = { diff --git a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.h b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.h index 356803d1c10e..c9fab51f16e2 100644 --- a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.h +++ b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.h @@ -6,6 +6,7 @@ #include struct task_struct; +struct cgroup; struct bpf_testmod_test_read_ctx { char *buf; @@ -36,6 +37,11 @@ struct bpf_testmod_ops { /* Used to test nullable arguments. */ int (*test_maybe_null)(int dummy, struct task_struct *task); int (*unsupported_ops)(void); + /* Used to test ref_acquired arguments. */ + int (*test_refcounted)(int dummy, struct task_struct *task); + /* Used to test returning referenced kptr. */ + struct task_struct *(*test_return_ref_kptr)(int dummy, struct task_struct *task, + struct cgroup *cgrp); /* The following fields are used to test shadow copies. */ char onebyte;