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-rw-r--r--arch/x86/net/bpf_jit_comp.c32
-rw-r--r--include/linux/bpf.h3
-rw-r--r--include/uapi/linux/bpf.h8
-rw-r--r--init/Kconfig1
-rw-r--r--kernel/bpf/arraymap.c1
-rw-r--r--kernel/bpf/hashtab.c12
-rw-r--r--kernel/bpf/syscall.c13
-rw-r--r--kernel/bpf/trampoline.c28
-rw-r--r--kernel/bpf/verifier.c81
-rw-r--r--tools/include/uapi/linux/bpf.h8
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 42b6709e6dc7..7d9ea7b41c71 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 dbba82a80087..4dd7e927621d 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 ef7af384f5ee..6e8b706aeb05 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 fc10f7ede5f6..6ecc00e130ff 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 d851ebbcf302..e046fb7d17cd 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -10,6 +10,7 @@
#include <linux/filter.h>
#include <linux/perf_event.h>
#include <uapi/linux/btf.h>
+#include <linux/rcupdate_trace.h>
#include "map_in_map.h"
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index ad80f45774e7..fe0e06284d33 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -9,6 +9,7 @@
#include <linux/rculist_nulls.h>
#include <linux/random.h>
#include <uapi/linux/btf.h>
+#include <linux/rcupdate_trace.h>
#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 b86b1155b748..4108ef3b828b 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -29,6 +29,7 @@
#include <linux/bpf_lsm.h>
#include <linux/poll.h>
#include <linux/bpf-netns.h>
+#include <linux/rcupdate_trace.h>
#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 9be85aa4ec5f..c2b76545153c 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -7,6 +7,8 @@
#include <linux/rbtree_latch.h>
#include <linux/perf_event.h>
#include <linux/btf.h>
+#include <linux/rcupdate_trace.h>
+#include <linux/rcupdate_wait.h>
/* 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 6f5a9f51cc03..3ebfdb7bd427 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -21,6 +21,7 @@
#include <linux/ctype.h>
#include <linux/error-injection.h>
#include <linux/bpf_lsm.h>
+#include <linux/btf_ids.h>
#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 ef7af384f5ee..6e8b706aeb05 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:
*
generated by cgit v1.2.3 (git 2.25.1) at 2024-05-29 23:19:25 +0000