From 76cd61739fd107a7f7ec4c24a045e98d8ee150f0 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 27 Aug 2020 15:01:10 -0700 Subject: [PATCH 1/5] mm/error_inject: Fix allow_error_inject function signatures. 'static' and 'static noinline' function attributes make no guarantees that gcc/clang won't optimize them. The compiler may decide to inline 'static' function and in such case ALLOW_ERROR_INJECT becomes meaningless. The compiler could have inlined __add_to_page_cache_locked() in one callsite and didn't inline in another. In such case injecting errors into it would cause unpredictable behavior. It's worse with 'static noinline' which won't be inlined, but it still can be optimized. Like the compiler may decide to remove one argument or constant propagate the value depending on the callsite. To avoid such issues make sure that these functions are global noinline. Fixes: af3b854492f3 ("mm/page_alloc.c: allow error injection") Fixes: cfcbfb1382db ("mm/filemap.c: enable error injection at add_to_page_cache()") Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Reviewed-by: Josef Bacik Link: https://lore.kernel.org/bpf/20200827220114.69225-2-alexei.starovoitov@gmail.com --- mm/filemap.c | 8 ++++---- mm/page_alloc.c | 2 +- 2 files changed, 5 insertions(+), 5 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index 1aaea26556cc7..054d93a86f8a0 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -827,10 +827,10 @@ int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask) } EXPORT_SYMBOL_GPL(replace_page_cache_page); -static int __add_to_page_cache_locked(struct page *page, - struct address_space *mapping, - pgoff_t offset, gfp_t gfp_mask, - void **shadowp) +noinline int __add_to_page_cache_locked(struct page *page, + struct address_space *mapping, + pgoff_t offset, gfp_t gfp_mask, + void **shadowp) { XA_STATE(xas, &mapping->i_pages, offset); int huge = PageHuge(page); diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 0e2bab486fea6..cd8d8f0326fc9 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3477,7 +3477,7 @@ static inline bool __should_fail_alloc_page(gfp_t gfp_mask, unsigned int order) #endif /* CONFIG_FAIL_PAGE_ALLOC */ -static noinline bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order) +noinline bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order) { return __should_fail_alloc_page(gfp_mask, order); } From 1e6c62a8821557720a9b2ea9617359b264f2f67c Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 27 Aug 2020 15:01:11 -0700 Subject: [PATCH 2/5] bpf: Introduce sleepable BPF programs Introduce sleepable BPF programs that can request such property for themselves via BPF_F_SLEEPABLE flag at program load time. In such case they will be able to use helpers like bpf_copy_from_user() that might sleep. At present only fentry/fexit/fmod_ret and lsm programs can request to be sleepable and only when they are attached to kernel functions that are known to allow sleeping. The non-sleepable programs are relying on implicit rcu_read_lock() and migrate_disable() to protect life time of programs, maps that they use and per-cpu kernel structures used to pass info between bpf programs and the kernel. The sleepable programs cannot be enclosed into rcu_read_lock(). migrate_disable() maps to preempt_disable() in non-RT kernels, so the progs should not be enclosed in migrate_disable() as well. Therefore rcu_read_lock_trace is used to protect the life time of sleepable progs. There are many networking and tracing program types. In many cases the 'struct bpf_prog *' pointer itself is rcu protected within some other kernel data structure and the kernel code is using rcu_dereference() to load that program pointer and call BPF_PROG_RUN() on it. All these cases are not touched. Instead sleepable bpf programs are allowed with bpf trampoline only. The program pointers are hard-coded into generated assembly of bpf trampoline and synchronize_rcu_tasks_trace() is used to protect the life time of the program. The same trampoline can hold both sleepable and non-sleepable progs. When rcu_read_lock_trace is held it means that some sleepable bpf program is running from bpf trampoline. Those programs can use bpf arrays and preallocated hash/lru maps. These map types are waiting on programs to complete via synchronize_rcu_tasks_trace(); Updates to trampoline now has to do synchronize_rcu_tasks_trace() and synchronize_rcu_tasks() to wait for sleepable progs to finish and for trampoline assembly to finish. This is the first step of introducing sleepable progs. Eventually dynamically allocated hash maps can be allowed and networking program types can become sleepable too. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Reviewed-by: Josef Bacik Acked-by: Andrii Nakryiko Acked-by: KP Singh Link: https://lore.kernel.org/bpf/20200827220114.69225-3-alexei.starovoitov@gmail.com --- arch/x86/net/bpf_jit_comp.c | 32 +++++++++----- include/linux/bpf.h | 3 ++ include/uapi/linux/bpf.h | 8 ++++ init/Kconfig | 1 + kernel/bpf/arraymap.c | 1 + kernel/bpf/hashtab.c | 12 ++--- kernel/bpf/syscall.c | 13 ++++-- kernel/bpf/trampoline.c | 28 ++++++++++-- kernel/bpf/verifier.c | 81 +++++++++++++++++++++++++++++++++- tools/include/uapi/linux/bpf.h | 8 ++++ 10 files changed, 162 insertions(+), 25 deletions(-) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 42b6709e6dc7c..7d9ea7b41c714 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -1379,10 +1379,15 @@ static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog, u8 *prog = *pprog; int cnt = 0; - if (emit_call(&prog, __bpf_prog_enter, prog)) - return -EINVAL; - /* remember prog start time returned by __bpf_prog_enter */ - emit_mov_reg(&prog, true, BPF_REG_6, BPF_REG_0); + if (p->aux->sleepable) { + if (emit_call(&prog, __bpf_prog_enter_sleepable, prog)) + return -EINVAL; + } else { + if (emit_call(&prog, __bpf_prog_enter, prog)) + return -EINVAL; + /* remember prog start time returned by __bpf_prog_enter */ + emit_mov_reg(&prog, true, BPF_REG_6, BPF_REG_0); + } /* arg1: lea rdi, [rbp - stack_size] */ EMIT4(0x48, 0x8D, 0x7D, -stack_size); @@ -1402,13 +1407,18 @@ static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog, if (mod_ret) emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -8); - /* arg1: mov rdi, progs[i] */ - emit_mov_imm64(&prog, BPF_REG_1, (long) p >> 32, - (u32) (long) p); - /* arg2: mov rsi, rbx <- start time in nsec */ - emit_mov_reg(&prog, true, BPF_REG_2, BPF_REG_6); - if (emit_call(&prog, __bpf_prog_exit, prog)) - return -EINVAL; + if (p->aux->sleepable) { + if (emit_call(&prog, __bpf_prog_exit_sleepable, prog)) + return -EINVAL; + } else { + /* arg1: mov rdi, progs[i] */ + emit_mov_imm64(&prog, BPF_REG_1, (long) p >> 32, + (u32) (long) p); + /* arg2: mov rsi, rbx <- start time in nsec */ + emit_mov_reg(&prog, true, BPF_REG_2, BPF_REG_6); + if (emit_call(&prog, __bpf_prog_exit, prog)) + return -EINVAL; + } *pprog = prog; return 0; diff --git a/include/linux/bpf.h b/include/linux/bpf.h index dbba82a800878..4dd7e927621d1 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -539,6 +539,8 @@ int arch_prepare_bpf_trampoline(void *image, void *image_end, /* these two functions are called from generated trampoline */ u64 notrace __bpf_prog_enter(void); void notrace __bpf_prog_exit(struct bpf_prog *prog, u64 start); +void notrace __bpf_prog_enter_sleepable(void); +void notrace __bpf_prog_exit_sleepable(void); struct bpf_ksym { unsigned long start; @@ -734,6 +736,7 @@ struct bpf_prog_aux { bool offload_requested; bool attach_btf_trace; /* true if attaching to BTF-enabled raw tp */ bool func_proto_unreliable; + bool sleepable; enum bpf_tramp_prog_type trampoline_prog_type; struct bpf_trampoline *trampoline; struct hlist_node tramp_hlist; diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index ef7af384f5eea..6e8b706aeb050 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -346,6 +346,14 @@ enum bpf_link_type { /* The verifier internal test flag. Behavior is undefined */ #define BPF_F_TEST_STATE_FREQ (1U << 3) +/* If BPF_F_SLEEPABLE is used in BPF_PROG_LOAD command, the verifier will + * restrict map and helper usage for such programs. Sleepable BPF programs can + * only be attached to hooks where kernel execution context allows sleeping. + * Such programs are allowed to use helpers that may sleep like + * bpf_copy_from_user(). + */ +#define BPF_F_SLEEPABLE (1U << 4) + /* When BPF ldimm64's insn[0].src_reg != 0 then this can have * two extensions: * diff --git a/init/Kconfig b/init/Kconfig index fc10f7ede5f69..6ecc00e130ff3 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1691,6 +1691,7 @@ config BPF_SYSCALL bool "Enable bpf() system call" select BPF select IRQ_WORK + select TASKS_TRACE_RCU default n help Enable the bpf() system call that allows to manipulate eBPF diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index d851ebbcf3022..e046fb7d17cd0 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -10,6 +10,7 @@ #include #include #include +#include #include "map_in_map.h" diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index ad80f45774e75..fe0e06284d338 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -9,6 +9,7 @@ #include #include #include +#include #include "percpu_freelist.h" #include "bpf_lru_list.h" #include "map_in_map.h" @@ -577,8 +578,7 @@ static void *__htab_map_lookup_elem(struct bpf_map *map, void *key) struct htab_elem *l; u32 hash, key_size; - /* Must be called with rcu_read_lock. */ - WARN_ON_ONCE(!rcu_read_lock_held()); + WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held()); key_size = map->key_size; @@ -941,7 +941,7 @@ static int htab_map_update_elem(struct bpf_map *map, void *key, void *value, /* unknown flags */ return -EINVAL; - WARN_ON_ONCE(!rcu_read_lock_held()); + WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held()); key_size = map->key_size; @@ -1032,7 +1032,7 @@ static int htab_lru_map_update_elem(struct bpf_map *map, void *key, void *value, /* unknown flags */ return -EINVAL; - WARN_ON_ONCE(!rcu_read_lock_held()); + WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held()); key_size = map->key_size; @@ -1220,7 +1220,7 @@ static int htab_map_delete_elem(struct bpf_map *map, void *key) u32 hash, key_size; int ret = -ENOENT; - WARN_ON_ONCE(!rcu_read_lock_held()); + WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held()); key_size = map->key_size; @@ -1252,7 +1252,7 @@ static int htab_lru_map_delete_elem(struct bpf_map *map, void *key) u32 hash, key_size; int ret = -ENOENT; - WARN_ON_ONCE(!rcu_read_lock_held()); + WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held()); key_size = map->key_size; diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index b86b1155b7481..4108ef3b828b3 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -29,6 +29,7 @@ #include #include #include +#include #define IS_FD_ARRAY(map) ((map)->map_type == BPF_MAP_TYPE_PERF_EVENT_ARRAY || \ (map)->map_type == BPF_MAP_TYPE_CGROUP_ARRAY || \ @@ -1731,10 +1732,14 @@ static void __bpf_prog_put_noref(struct bpf_prog *prog, bool deferred) btf_put(prog->aux->btf); bpf_prog_free_linfo(prog); - if (deferred) - call_rcu(&prog->aux->rcu, __bpf_prog_put_rcu); - else + if (deferred) { + if (prog->aux->sleepable) + call_rcu_tasks_trace(&prog->aux->rcu, __bpf_prog_put_rcu); + else + call_rcu(&prog->aux->rcu, __bpf_prog_put_rcu); + } else { __bpf_prog_put_rcu(&prog->aux->rcu); + } } static void __bpf_prog_put(struct bpf_prog *prog, bool do_idr_lock) @@ -2104,6 +2109,7 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr) if (attr->prog_flags & ~(BPF_F_STRICT_ALIGNMENT | BPF_F_ANY_ALIGNMENT | BPF_F_TEST_STATE_FREQ | + BPF_F_SLEEPABLE | BPF_F_TEST_RND_HI32)) return -EINVAL; @@ -2159,6 +2165,7 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr) } prog->aux->offload_requested = !!attr->prog_ifindex; + prog->aux->sleepable = attr->prog_flags & BPF_F_SLEEPABLE; err = security_bpf_prog_alloc(prog->aux); if (err) diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 9be85aa4ec5f8..c2b76545153ce 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -7,6 +7,8 @@ #include #include #include +#include +#include /* dummy _ops. The verifier will operate on target program's ops. */ const struct bpf_verifier_ops bpf_extension_verifier_ops = { @@ -210,9 +212,12 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr) * updates to trampoline would change the code from underneath the * preempted task. Hence wait for tasks to voluntarily schedule or go * to userspace. + * The same trampoline can hold both sleepable and non-sleepable progs. + * synchronize_rcu_tasks_trace() is needed to make sure all sleepable + * programs finish executing. + * Wait for these two grace periods together. */ - - synchronize_rcu_tasks(); + synchronize_rcu_mult(call_rcu_tasks, call_rcu_tasks_trace); err = arch_prepare_bpf_trampoline(new_image, new_image + PAGE_SIZE / 2, &tr->func.model, flags, tprogs, @@ -344,7 +349,14 @@ void bpf_trampoline_put(struct bpf_trampoline *tr) if (WARN_ON_ONCE(!hlist_empty(&tr->progs_hlist[BPF_TRAMP_FEXIT]))) goto out; bpf_image_ksym_del(&tr->ksym); - /* wait for tasks to get out of trampoline before freeing it */ + /* This code will be executed when all bpf progs (both sleepable and + * non-sleepable) went through + * bpf_prog_put()->call_rcu[_tasks_trace]()->bpf_prog_free_deferred(). + * Hence no need for another synchronize_rcu_tasks_trace() here, + * but synchronize_rcu_tasks() is still needed, since trampoline + * may not have had any sleepable programs and we need to wait + * for tasks to get out of trampoline code before freeing it. + */ synchronize_rcu_tasks(); bpf_jit_free_exec(tr->image); hlist_del(&tr->hlist); @@ -394,6 +406,16 @@ void notrace __bpf_prog_exit(struct bpf_prog *prog, u64 start) rcu_read_unlock(); } +void notrace __bpf_prog_enter_sleepable(void) +{ + rcu_read_lock_trace(); +} + +void notrace __bpf_prog_exit_sleepable(void) +{ + rcu_read_unlock_trace(); +} + int __weak arch_prepare_bpf_trampoline(void *image, void *image_end, const struct btf_func_model *m, u32 flags, diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 6f5a9f51cc03d..3ebfdb7bd4273 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -21,6 +21,7 @@ #include #include #include +#include #include "disasm.h" @@ -9367,6 +9368,23 @@ static int check_map_prog_compatibility(struct bpf_verifier_env *env, return -EINVAL; } + if (prog->aux->sleepable) + switch (map->map_type) { + case BPF_MAP_TYPE_HASH: + case BPF_MAP_TYPE_LRU_HASH: + case BPF_MAP_TYPE_ARRAY: + if (!is_preallocated_map(map)) { + verbose(env, + "Sleepable programs can only use preallocated hash maps\n"); + return -EINVAL; + } + break; + default: + verbose(env, + "Sleepable programs can only use array and hash maps\n"); + return -EINVAL; + } + return 0; } @@ -10985,6 +11003,36 @@ static int check_attach_modify_return(struct bpf_prog *prog, unsigned long addr) return -EINVAL; } +/* non exhaustive list of sleepable bpf_lsm_*() functions */ +BTF_SET_START(btf_sleepable_lsm_hooks) +#ifdef CONFIG_BPF_LSM +BTF_ID(func, bpf_lsm_file_mprotect) +BTF_ID(func, bpf_lsm_bprm_committed_creds) +#endif +BTF_SET_END(btf_sleepable_lsm_hooks) + +static int check_sleepable_lsm_hook(u32 btf_id) +{ + return btf_id_set_contains(&btf_sleepable_lsm_hooks, btf_id); +} + +/* list of non-sleepable functions that are otherwise on + * ALLOW_ERROR_INJECTION list + */ +BTF_SET_START(btf_non_sleepable_error_inject) +/* Three functions below can be called from sleepable and non-sleepable context. + * Assume non-sleepable from bpf safety point of view. + */ +BTF_ID(func, __add_to_page_cache_locked) +BTF_ID(func, should_fail_alloc_page) +BTF_ID(func, should_failslab) +BTF_SET_END(btf_non_sleepable_error_inject) + +static int check_non_sleepable_error_inject(u32 btf_id) +{ + return btf_id_set_contains(&btf_non_sleepable_error_inject, btf_id); +} + static int check_attach_btf_id(struct bpf_verifier_env *env) { struct bpf_prog *prog = env->prog; @@ -11002,6 +11050,12 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) long addr; u64 key; + if (prog->aux->sleepable && prog->type != BPF_PROG_TYPE_TRACING && + prog->type != BPF_PROG_TYPE_LSM) { + verbose(env, "Only fentry/fexit/fmod_ret and lsm programs can be sleepable\n"); + return -EINVAL; + } + if (prog->type == BPF_PROG_TYPE_STRUCT_OPS) return check_struct_ops_btf_id(env); @@ -11210,13 +11264,36 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) } } - if (prog->expected_attach_type == BPF_MODIFY_RETURN) { + if (prog->aux->sleepable) { + ret = -EINVAL; + switch (prog->type) { + case BPF_PROG_TYPE_TRACING: + /* fentry/fexit/fmod_ret progs can be sleepable only if they are + * attached to ALLOW_ERROR_INJECTION and are not in denylist. + */ + if (!check_non_sleepable_error_inject(btf_id) && + within_error_injection_list(addr)) + ret = 0; + break; + case BPF_PROG_TYPE_LSM: + /* LSM progs check that they are attached to bpf_lsm_*() funcs. + * Only some of them are sleepable. + */ + if (check_sleepable_lsm_hook(btf_id)) + ret = 0; + break; + default: + break; + } + if (ret) + verbose(env, "%s is not sleepable\n", + prog->aux->attach_func_name); + } else if (prog->expected_attach_type == BPF_MODIFY_RETURN) { ret = check_attach_modify_return(prog, addr); if (ret) verbose(env, "%s() is not modifiable\n", prog->aux->attach_func_name); } - if (ret) goto out; tr->func.addr = (void *)addr; diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index ef7af384f5eea..6e8b706aeb050 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -346,6 +346,14 @@ enum bpf_link_type { /* The verifier internal test flag. Behavior is undefined */ #define BPF_F_TEST_STATE_FREQ (1U << 3) +/* If BPF_F_SLEEPABLE is used in BPF_PROG_LOAD command, the verifier will + * restrict map and helper usage for such programs. Sleepable BPF programs can + * only be attached to hooks where kernel execution context allows sleeping. + * Such programs are allowed to use helpers that may sleep like + * bpf_copy_from_user(). + */ +#define BPF_F_SLEEPABLE (1U << 4) + /* When BPF ldimm64's insn[0].src_reg != 0 then this can have * two extensions: * From 07be4c4a3e7a0db148e44b16c5190e753d1c8569 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 27 Aug 2020 15:01:12 -0700 Subject: [PATCH 3/5] bpf: Add bpf_copy_from_user() helper. Sleepable BPF programs can now use copy_from_user() to access user memory. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Acked-by: KP Singh Link: https://lore.kernel.org/bpf/20200827220114.69225-4-alexei.starovoitov@gmail.com --- include/linux/bpf.h | 1 + include/uapi/linux/bpf.h | 8 ++++++++ kernel/bpf/helpers.c | 22 ++++++++++++++++++++++ kernel/trace/bpf_trace.c | 2 ++ tools/include/uapi/linux/bpf.h | 8 ++++++++ 5 files changed, 41 insertions(+) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 4dd7e927621d1..c6d9f2c444f40 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1784,6 +1784,7 @@ extern const struct bpf_func_proto bpf_skc_to_tcp_sock_proto; extern const struct bpf_func_proto bpf_skc_to_tcp_timewait_sock_proto; extern const struct bpf_func_proto bpf_skc_to_tcp_request_sock_proto; extern const struct bpf_func_proto bpf_skc_to_udp6_sock_proto; +extern const struct bpf_func_proto bpf_copy_from_user_proto; const struct bpf_func_proto *bpf_tracing_func_proto( enum bpf_func_id func_id, const struct bpf_prog *prog); diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 6e8b706aeb050..a613750d55158 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -3569,6 +3569,13 @@ union bpf_attr { * On success, the strictly positive length of the string, * including the trailing NUL character. On error, a negative * value. + * + * long bpf_copy_from_user(void *dst, u32 size, const void *user_ptr) + * Description + * Read *size* bytes from user space address *user_ptr* and store + * the data in *dst*. This is a wrapper of copy_from_user(). + * Return + * 0 on success, or a negative error in case of failure. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3719,6 +3726,7 @@ union bpf_attr { FN(inode_storage_get), \ FN(inode_storage_delete), \ FN(d_path), \ + FN(copy_from_user), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index be43ab3e619f9..5cc7425ee476b 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -601,6 +601,28 @@ const struct bpf_func_proto bpf_event_output_data_proto = { .arg5_type = ARG_CONST_SIZE_OR_ZERO, }; +BPF_CALL_3(bpf_copy_from_user, void *, dst, u32, size, + const void __user *, user_ptr) +{ + int ret = copy_from_user(dst, user_ptr, size); + + if (unlikely(ret)) { + memset(dst, 0, size); + ret = -EFAULT; + } + + return ret; +} + +const struct bpf_func_proto bpf_copy_from_user_proto = { + .func = bpf_copy_from_user, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_UNINIT_MEM, + .arg2_type = ARG_CONST_SIZE_OR_ZERO, + .arg3_type = ARG_ANYTHING, +}; + const struct bpf_func_proto bpf_get_current_task_proto __weak; const struct bpf_func_proto bpf_probe_read_user_proto __weak; const struct bpf_func_proto bpf_probe_read_user_str_proto __weak; diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index d973d891f2e25..b2a5380eb1871 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1228,6 +1228,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_jiffies64_proto; case BPF_FUNC_get_task_stack: return &bpf_get_task_stack_proto; + case BPF_FUNC_copy_from_user: + return prog->aux->sleepable ? &bpf_copy_from_user_proto : NULL; default: return NULL; } diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 6e8b706aeb050..a613750d55158 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -3569,6 +3569,13 @@ union bpf_attr { * On success, the strictly positive length of the string, * including the trailing NUL character. On error, a negative * value. + * + * long bpf_copy_from_user(void *dst, u32 size, const void *user_ptr) + * Description + * Read *size* bytes from user space address *user_ptr* and store + * the data in *dst*. This is a wrapper of copy_from_user(). + * Return + * 0 on success, or a negative error in case of failure. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3719,6 +3726,7 @@ union bpf_attr { FN(inode_storage_get), \ FN(inode_storage_delete), \ FN(d_path), \ + FN(copy_from_user), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper From 2b288740a1072235166b2706e139f2725b5ea26f Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 27 Aug 2020 15:01:13 -0700 Subject: [PATCH 4/5] libbpf: Support sleepable progs Pass request to load program as sleepable via ".s" suffix in the section name. If it happens in the future that all map types and helpers are allowed with BPF_F_SLEEPABLE flag "fmod_ret/" and "lsm/" can be aliased to "fmod_ret.s/" and "lsm.s/" to make all lsm and fmod_ret programs sleepable by default. The fentry and fexit programs would always need to have sleepable vs non-sleepable distinction, since not all fentry/fexit progs will be attached to sleepable kernel functions. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: KP Singh Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20200827220114.69225-5-alexei.starovoitov@gmail.com --- tools/lib/bpf/libbpf.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 8cdb2528482e9..b688aadf09c5d 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -208,6 +208,7 @@ struct bpf_sec_def { bool is_exp_attach_type_optional; bool is_attachable; bool is_attach_btf; + bool is_sleepable; attach_fn_t attach_fn; }; @@ -6291,6 +6292,8 @@ __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz, /* couldn't guess, but user might manually specify */ continue; + if (prog->sec_def->is_sleepable) + prog->prog_flags |= BPF_F_SLEEPABLE; bpf_program__set_type(prog, prog->sec_def->prog_type); bpf_program__set_expected_attach_type(prog, prog->sec_def->expected_attach_type); @@ -7559,6 +7562,21 @@ static const struct bpf_sec_def section_defs[] = { .expected_attach_type = BPF_TRACE_FEXIT, .is_attach_btf = true, .attach_fn = attach_trace), + SEC_DEF("fentry.s/", TRACING, + .expected_attach_type = BPF_TRACE_FENTRY, + .is_attach_btf = true, + .is_sleepable = true, + .attach_fn = attach_trace), + SEC_DEF("fmod_ret.s/", TRACING, + .expected_attach_type = BPF_MODIFY_RETURN, + .is_attach_btf = true, + .is_sleepable = true, + .attach_fn = attach_trace), + SEC_DEF("fexit.s/", TRACING, + .expected_attach_type = BPF_TRACE_FEXIT, + .is_attach_btf = true, + .is_sleepable = true, + .attach_fn = attach_trace), SEC_DEF("freplace/", EXT, .is_attach_btf = true, .attach_fn = attach_trace), @@ -7566,6 +7584,11 @@ static const struct bpf_sec_def section_defs[] = { .is_attach_btf = true, .expected_attach_type = BPF_LSM_MAC, .attach_fn = attach_lsm), + SEC_DEF("lsm.s/", LSM, + .is_attach_btf = true, + .is_sleepable = true, + .expected_attach_type = BPF_LSM_MAC, + .attach_fn = attach_lsm), SEC_DEF("iter/", TRACING, .expected_attach_type = BPF_TRACE_ITER, .is_attach_btf = true, @@ -8288,7 +8311,7 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr, prog->prog_ifindex = attr->ifindex; prog->log_level = attr->log_level; - prog->prog_flags = attr->prog_flags; + prog->prog_flags |= attr->prog_flags; if (!first_prog) first_prog = prog; } From e68a144547fc7a956952260539cb7b8bb9afbcc0 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 27 Aug 2020 15:01:14 -0700 Subject: [PATCH 5/5] selftests/bpf: Add sleepable tests Modify few tests to sanity test sleepable bpf functionality. Running 'bench trig-fentry-sleep' vs 'bench trig-fentry' and 'perf report': sleepable with SRCU: 3.86% bench [k] __srcu_read_unlock 3.22% bench [k] __srcu_read_lock 0.92% bench [k] bpf_prog_740d4210cdcd99a3_bench_trigger_fentry_sleep 0.50% bench [k] bpf_trampoline_10297 0.26% bench [k] __bpf_prog_exit_sleepable 0.21% bench [k] __bpf_prog_enter_sleepable sleepable with RCU_TRACE: 0.79% bench [k] bpf_prog_740d4210cdcd99a3_bench_trigger_fentry_sleep 0.72% bench [k] bpf_trampoline_10381 0.31% bench [k] __bpf_prog_exit_sleepable 0.29% bench [k] __bpf_prog_enter_sleepable non-sleepable with RCU: 0.88% bench [k] bpf_prog_740d4210cdcd99a3_bench_trigger_fentry 0.84% bench [k] bpf_trampoline_10297 0.13% bench [k] __bpf_prog_enter 0.12% bench [k] __bpf_prog_exit Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: KP Singh Link: https://lore.kernel.org/bpf/20200827220114.69225-6-alexei.starovoitov@gmail.com --- tools/testing/selftests/bpf/bench.c | 2 + .../selftests/bpf/benchs/bench_trigger.c | 17 +++++ .../selftests/bpf/prog_tests/test_lsm.c | 9 +++ tools/testing/selftests/bpf/progs/lsm.c | 66 ++++++++++++++++++- .../selftests/bpf/progs/trigger_bench.c | 7 ++ 5 files changed, 99 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/bpf/bench.c b/tools/testing/selftests/bpf/bench.c index 944ad4721c83c..1a427685a8a8f 100644 --- a/tools/testing/selftests/bpf/bench.c +++ b/tools/testing/selftests/bpf/bench.c @@ -317,6 +317,7 @@ extern const struct bench bench_trig_tp; extern const struct bench bench_trig_rawtp; extern const struct bench bench_trig_kprobe; extern const struct bench bench_trig_fentry; +extern const struct bench bench_trig_fentry_sleep; extern const struct bench bench_trig_fmodret; extern const struct bench bench_rb_libbpf; extern const struct bench bench_rb_custom; @@ -338,6 +339,7 @@ static const struct bench *benchs[] = { &bench_trig_rawtp, &bench_trig_kprobe, &bench_trig_fentry, + &bench_trig_fentry_sleep, &bench_trig_fmodret, &bench_rb_libbpf, &bench_rb_custom, diff --git a/tools/testing/selftests/bpf/benchs/bench_trigger.c b/tools/testing/selftests/bpf/benchs/bench_trigger.c index 49c22832f2169..2a0b6c9885a46 100644 --- a/tools/testing/selftests/bpf/benchs/bench_trigger.c +++ b/tools/testing/selftests/bpf/benchs/bench_trigger.c @@ -90,6 +90,12 @@ static void trigger_fentry_setup() attach_bpf(ctx.skel->progs.bench_trigger_fentry); } +static void trigger_fentry_sleep_setup() +{ + setup_ctx(); + attach_bpf(ctx.skel->progs.bench_trigger_fentry_sleep); +} + static void trigger_fmodret_setup() { setup_ctx(); @@ -155,6 +161,17 @@ const struct bench bench_trig_fentry = { .report_final = hits_drops_report_final, }; +const struct bench bench_trig_fentry_sleep = { + .name = "trig-fentry-sleep", + .validate = trigger_validate, + .setup = trigger_fentry_sleep_setup, + .producer_thread = trigger_producer, + .consumer_thread = trigger_consumer, + .measure = trigger_measure, + .report_progress = hits_drops_report_progress, + .report_final = hits_drops_report_final, +}; + const struct bench bench_trig_fmodret = { .name = "trig-fmodret", .validate = trigger_validate, diff --git a/tools/testing/selftests/bpf/prog_tests/test_lsm.c b/tools/testing/selftests/bpf/prog_tests/test_lsm.c index b17eb2045c1d1..6ab29226c99b6 100644 --- a/tools/testing/selftests/bpf/prog_tests/test_lsm.c +++ b/tools/testing/selftests/bpf/prog_tests/test_lsm.c @@ -10,6 +10,7 @@ #include #include #include +#include #include "lsm.skel.h" @@ -55,6 +56,7 @@ void test_test_lsm(void) { struct lsm *skel = NULL; int err, duration = 0; + int buf = 1234; skel = lsm__open_and_load(); if (CHECK(!skel, "skel_load", "lsm skeleton failed\n")) @@ -81,6 +83,13 @@ void test_test_lsm(void) CHECK(skel->bss->mprotect_count != 1, "mprotect_count", "mprotect_count = %d\n", skel->bss->mprotect_count); + syscall(__NR_setdomainname, &buf, -2L); + syscall(__NR_setdomainname, 0, -3L); + syscall(__NR_setdomainname, ~0L, -4L); + + CHECK(skel->bss->copy_test != 3, "copy_test", + "copy_test = %d\n", skel->bss->copy_test); + close_prog: lsm__destroy(skel); } diff --git a/tools/testing/selftests/bpf/progs/lsm.c b/tools/testing/selftests/bpf/progs/lsm.c index b4598d4bc4f73..49fa6ca99755a 100644 --- a/tools/testing/selftests/bpf/progs/lsm.c +++ b/tools/testing/selftests/bpf/progs/lsm.c @@ -9,16 +9,41 @@ #include #include +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __uint(max_entries, 1); + __type(key, __u32); + __type(value, __u64); +} array SEC(".maps"); + +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __uint(max_entries, 1); + __type(key, __u32); + __type(value, __u64); +} hash SEC(".maps"); + +struct { + __uint(type, BPF_MAP_TYPE_LRU_HASH); + __uint(max_entries, 1); + __type(key, __u32); + __type(value, __u64); +} lru_hash SEC(".maps"); + char _license[] SEC("license") = "GPL"; int monitored_pid = 0; int mprotect_count = 0; int bprm_count = 0; -SEC("lsm/file_mprotect") +SEC("lsm.s/file_mprotect") int BPF_PROG(test_int_hook, struct vm_area_struct *vma, unsigned long reqprot, unsigned long prot, int ret) { + char args[64]; + __u32 key = 0; + __u64 *value; + if (ret != 0) return ret; @@ -28,6 +53,18 @@ int BPF_PROG(test_int_hook, struct vm_area_struct *vma, is_stack = (vma->vm_start <= vma->vm_mm->start_stack && vma->vm_end >= vma->vm_mm->start_stack); + bpf_copy_from_user(args, sizeof(args), (void *)vma->vm_mm->arg_start); + + value = bpf_map_lookup_elem(&array, &key); + if (value) + *value = 0; + value = bpf_map_lookup_elem(&hash, &key); + if (value) + *value = 0; + value = bpf_map_lookup_elem(&lru_hash, &key); + if (value) + *value = 0; + if (is_stack && monitored_pid == pid) { mprotect_count++; ret = -EPERM; @@ -36,7 +73,7 @@ int BPF_PROG(test_int_hook, struct vm_area_struct *vma, return ret; } -SEC("lsm/bprm_committed_creds") +SEC("lsm.s/bprm_committed_creds") int BPF_PROG(test_void_hook, struct linux_binprm *bprm) { __u32 pid = bpf_get_current_pid_tgid() >> 32; @@ -46,3 +83,28 @@ int BPF_PROG(test_void_hook, struct linux_binprm *bprm) return 0; } +SEC("lsm/task_free") /* lsm/ is ok, lsm.s/ fails */ +int BPF_PROG(test_task_free, struct task_struct *task) +{ + return 0; +} + +int copy_test = 0; + +SEC("fentry.s/__x64_sys_setdomainname") +int BPF_PROG(test_sys_setdomainname, struct pt_regs *regs) +{ + void *ptr = (void *)PT_REGS_PARM1(regs); + int len = PT_REGS_PARM2(regs); + int buf = 0; + long ret; + + ret = bpf_copy_from_user(&buf, sizeof(buf), ptr); + if (len == -2 && ret == 0 && buf == 1234) + copy_test++; + if (len == -3 && ret == -EFAULT) + copy_test++; + if (len == -4 && ret == -EFAULT) + copy_test++; + return 0; +} diff --git a/tools/testing/selftests/bpf/progs/trigger_bench.c b/tools/testing/selftests/bpf/progs/trigger_bench.c index 8b36b6640e7e9..9a4d09590b3dc 100644 --- a/tools/testing/selftests/bpf/progs/trigger_bench.c +++ b/tools/testing/selftests/bpf/progs/trigger_bench.c @@ -39,6 +39,13 @@ int bench_trigger_fentry(void *ctx) return 0; } +SEC("fentry.s/__x64_sys_getpgid") +int bench_trigger_fentry_sleep(void *ctx) +{ + __sync_add_and_fetch(&hits, 1); + return 0; +} + SEC("fmod_ret/__x64_sys_getpgid") int bench_trigger_fmodret(void *ctx) {