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Message-ID: <20190128025010.342241-2-ast@kernel.org>
Date: Sun, 27 Jan 2019 18:50:02 -0800
From: Alexei Starovoitov <ast@...nel.org>
To: <davem@...emloft.net>
CC: <daniel@...earbox.net>, <peterz@...radead.org>, <jannh@...gle.com>,
<paulmck@...ux.ibm.com>, <will.deacon@....com>, <mingo@...hat.com>,
<netdev@...r.kernel.org>, <kernel-team@...com>
Subject: [PATCH v5 bpf-next 1/9] bpf: introduce bpf_spin_lock
Introduce 'struct bpf_spin_lock' and bpf_spin_lock/unlock() helpers to let
bpf program serialize access to other variables.
Example:
struct hash_elem {
int cnt;
struct bpf_spin_lock lock;
};
struct hash_elem * val = bpf_map_lookup_elem(&hash_map, &key);
if (val) {
bpf_spin_lock(&val->lock);
val->cnt++;
bpf_spin_unlock(&val->lock);
}
Restrictions and safety checks:
- bpf_spin_lock is only allowed inside HASH and ARRAY maps.
- BTF description of the map is mandatory for safety analysis.
- bpf program can take one bpf_spin_lock at a time, since two or more can
cause dead locks.
- only one 'struct bpf_spin_lock' is allowed per map element.
It drastically simplifies implementation yet allows bpf program to use
any number of bpf_spin_locks.
- when bpf_spin_lock is taken the calls (either bpf2bpf or helpers) are not allowed.
- bpf program must bpf_spin_unlock() before return.
- bpf program can access 'struct bpf_spin_lock' only via
bpf_spin_lock()/bpf_spin_unlock() helpers.
- load/store into 'struct bpf_spin_lock lock;' field is not allowed.
- to use bpf_spin_lock() helper the BTF description of map value must be
a struct and have 'struct bpf_spin_lock anyname;' field at the top level.
Nested lock inside another struct is not allowed.
- syscall map_lookup doesn't copy bpf_spin_lock field to user space.
- syscall map_update and program map_update do not update bpf_spin_lock field.
- bpf_spin_lock cannot be on the stack or inside networking packet.
bpf_spin_lock can only be inside HASH or ARRAY map value.
- bpf_spin_lock is available to root only and to all program types.
- bpf_spin_lock is not allowed in inner maps of map-in-map.
- ld_abs is not allowed inside spin_lock-ed region.
- tracing progs cannot use bpf_spin_lock yet due to insufficient preemption checks
- socket filter progs cannot use bpf_spin_lock due to missing preempt_disable
Implementation details:
- on !SMP bpf_spin_lock() becomes nop
- on architectures that don't support queued_spin_lock trivial lock is used.
Note that arch_spin_lock cannot be used, since not all archs agree that
zero == unlocked and sizeof(arch_spinlock_t) != sizeof(__u32).
- presence of bpf_spin_lock inside map value could have been indicated via
extra flag during map_create, but specifying it via BTF is cleaner.
It provides introspection for map key/value and reduces user coding mistakes.
Next steps:
- allow bpf_spin_lock in other map types (like cgroup local storage)
- introduce BPF_F_LOCK flag for bpf_map_update() syscall and helper
to request kernel to grab bpf_spin_lock before rewriting the value.
That will serialize access to map elements.
Signed-off-by: Alexei Starovoitov <ast@...nel.org>
---
include/linux/bpf.h | 37 +++++++-
include/linux/bpf_verifier.h | 1 +
include/linux/btf.h | 1 +
include/uapi/linux/bpf.h | 7 +-
kernel/bpf/arraymap.c | 7 +-
kernel/bpf/btf.c | 42 +++++++++
kernel/bpf/core.c | 2 +
kernel/bpf/hashtab.c | 21 +++--
kernel/bpf/helpers.c | 57 ++++++++++++
kernel/bpf/map_in_map.c | 5 ++
kernel/bpf/syscall.c | 21 ++++-
kernel/bpf/verifier.c | 169 ++++++++++++++++++++++++++++++++++-
net/core/filter.c | 16 +++-
13 files changed, 360 insertions(+), 26 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 3851529062ec..ee0352bd728f 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -72,14 +72,15 @@ struct bpf_map {
u32 value_size;
u32 max_entries;
u32 map_flags;
- u32 pages;
+ int spin_lock_off; /* >=0 valid offset, <0 error */
u32 id;
int numa_node;
u32 btf_key_type_id;
u32 btf_value_type_id;
struct btf *btf;
+ u32 pages;
bool unpriv_array;
- /* 55 bytes hole */
+ /* 51 bytes hole */
/* The 3rd and 4th cacheline with misc members to avoid false sharing
* particularly with refcounting.
@@ -91,6 +92,34 @@ struct bpf_map {
char name[BPF_OBJ_NAME_LEN];
};
+static inline bool map_value_has_spin_lock(const struct bpf_map *map)
+{
+ return map->spin_lock_off >= 0;
+}
+
+static inline void check_and_init_map_lock(struct bpf_map *map, void *dst)
+{
+ if (likely(!map_value_has_spin_lock(map)))
+ return;
+ *(struct bpf_spin_lock *)(dst + map->spin_lock_off) =
+ (struct bpf_spin_lock){};
+}
+
+/* copy everything but bpf_spin_lock */
+static inline void copy_map_value(struct bpf_map *map, void *dst, void *src)
+{
+ if (unlikely(map_value_has_spin_lock(map))) {
+ u32 off = map->spin_lock_off;
+
+ memcpy(dst, src, off);
+ memcpy(dst + off + sizeof(struct bpf_spin_lock),
+ src + off + sizeof(struct bpf_spin_lock),
+ map->value_size - off - sizeof(struct bpf_spin_lock));
+ } else {
+ memcpy(dst, src, map->value_size);
+ }
+}
+
struct bpf_offload_dev;
struct bpf_offloaded_map;
@@ -162,6 +191,7 @@ enum bpf_arg_type {
ARG_PTR_TO_CTX, /* pointer to context */
ARG_ANYTHING, /* any (initialized) argument is ok */
ARG_PTR_TO_SOCKET, /* pointer to bpf_sock */
+ ARG_PTR_TO_SPIN_LOCK, /* pointer to bpf_spin_lock */
};
/* type of values returned from helper functions */
@@ -876,7 +906,8 @@ extern const struct bpf_func_proto bpf_msg_redirect_hash_proto;
extern const struct bpf_func_proto bpf_msg_redirect_map_proto;
extern const struct bpf_func_proto bpf_sk_redirect_hash_proto;
extern const struct bpf_func_proto bpf_sk_redirect_map_proto;
-
+extern const struct bpf_func_proto bpf_spin_lock_proto;
+extern const struct bpf_func_proto bpf_spin_unlock_proto;
extern const struct bpf_func_proto bpf_get_local_storage_proto;
/* Shared helpers among cBPF and eBPF. */
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 0620e418dde5..69f7a3449eda 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -148,6 +148,7 @@ struct bpf_verifier_state {
/* call stack tracking */
struct bpf_func_state *frame[MAX_CALL_FRAMES];
u32 curframe;
+ u32 active_spin_lock;
bool speculative;
};
diff --git a/include/linux/btf.h b/include/linux/btf.h
index 12502e25e767..455d31b55828 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -50,6 +50,7 @@ u32 btf_id(const struct btf *btf);
bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s,
const struct btf_member *m,
u32 expected_offset, u32 expected_size);
+int btf_find_spin_lock(const struct btf *btf, const struct btf_type *t);
#ifdef CONFIG_BPF_SYSCALL
const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id);
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 60b99b730a41..86f7c438d40f 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -2422,7 +2422,9 @@ union bpf_attr {
FN(map_peek_elem), \
FN(msg_push_data), \
FN(msg_pop_data), \
- FN(rc_pointer_rel),
+ FN(rc_pointer_rel), \
+ FN(spin_lock), \
+ FN(spin_unlock),
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call
@@ -3056,4 +3058,7 @@ struct bpf_line_info {
__u32 line_col;
};
+struct bpf_spin_lock {
+ __u32 val;
+};
#endif /* _UAPI__LINUX_BPF_H__ */
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 25632a75d630..d6d979910a2a 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -270,9 +270,10 @@ static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
memcpy(this_cpu_ptr(array->pptrs[index & array->index_mask]),
value, map->value_size);
else
- memcpy(array->value +
- array->elem_size * (index & array->index_mask),
- value, map->value_size);
+ copy_map_value(map,
+ array->value +
+ array->elem_size * (index & array->index_mask),
+ value);
return 0;
}
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 022ef9ca1296..03b1a7a6195c 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -355,6 +355,11 @@ static bool btf_type_is_struct(const struct btf_type *t)
return kind == BTF_KIND_STRUCT || kind == BTF_KIND_UNION;
}
+static bool __btf_type_is_struct(const struct btf_type *t)
+{
+ return BTF_INFO_KIND(t->info) == BTF_KIND_STRUCT;
+}
+
static bool btf_type_is_array(const struct btf_type *t)
{
return BTF_INFO_KIND(t->info) == BTF_KIND_ARRAY;
@@ -2045,6 +2050,43 @@ static void btf_struct_log(struct btf_verifier_env *env,
btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
}
+/* find 'struct bpf_spin_lock' in map value.
+ * return >= 0 offset if found
+ * and < 0 in case of error
+ */
+int btf_find_spin_lock(const struct btf *btf, const struct btf_type *t)
+{
+ const struct btf_member *member;
+ u32 i, off = -ENOENT;
+
+ if (!__btf_type_is_struct(t))
+ return -EINVAL;
+
+ for_each_member(i, t, member) {
+ const struct btf_type *member_type = btf_type_by_id(btf,
+ member->type);
+ if (!__btf_type_is_struct(member_type))
+ continue;
+ if (member_type->size != sizeof(struct bpf_spin_lock))
+ continue;
+ if (strcmp(__btf_name_by_offset(btf, member_type->name_off),
+ "bpf_spin_lock"))
+ continue;
+ if (off != -ENOENT)
+ /* only one 'struct bpf_spin_lock' is allowed */
+ return -E2BIG;
+ off = btf_member_bit_offset(t, member);
+ if (off % 8)
+ /* valid C code cannot generate such BTF */
+ return -EINVAL;
+ off /= 8;
+ if (off % __alignof__(struct bpf_spin_lock))
+ /* valid struct bpf_spin_lock will be 4 byte aligned */
+ return -EINVAL;
+ }
+ return off;
+}
+
static void btf_struct_seq_show(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offset,
struct seq_file *m)
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index a7bcb23bee84..550d9f9298f3 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2001,6 +2001,8 @@ const struct bpf_func_proto bpf_map_delete_elem_proto __weak;
const struct bpf_func_proto bpf_map_push_elem_proto __weak;
const struct bpf_func_proto bpf_map_pop_elem_proto __weak;
const struct bpf_func_proto bpf_map_peek_elem_proto __weak;
+const struct bpf_func_proto bpf_spin_lock_proto __weak;
+const struct bpf_func_proto bpf_spin_unlock_proto __weak;
const struct bpf_func_proto bpf_get_prandom_u32_proto __weak;
const struct bpf_func_proto bpf_get_smp_processor_id_proto __weak;
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 4b7c76765d9d..6d3b22c5ad68 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -718,21 +718,12 @@ static bool fd_htab_map_needs_adjust(const struct bpf_htab *htab)
BITS_PER_LONG == 64;
}
-static u32 htab_size_value(const struct bpf_htab *htab, bool percpu)
-{
- u32 size = htab->map.value_size;
-
- if (percpu || fd_htab_map_needs_adjust(htab))
- size = round_up(size, 8);
- return size;
-}
-
static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
void *value, u32 key_size, u32 hash,
bool percpu, bool onallcpus,
struct htab_elem *old_elem)
{
- u32 size = htab_size_value(htab, percpu);
+ u32 size = htab->map.value_size;
bool prealloc = htab_is_prealloc(htab);
struct htab_elem *l_new, **pl_new;
void __percpu *pptr;
@@ -770,10 +761,13 @@ static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
l_new = ERR_PTR(-ENOMEM);
goto dec_count;
}
+ check_and_init_map_lock(&htab->map,
+ l_new->key + round_up(key_size, 8));
}
memcpy(l_new->key, key, key_size);
if (percpu) {
+ size = round_up(size, 8);
if (prealloc) {
pptr = htab_elem_get_ptr(l_new, key_size);
} else {
@@ -791,8 +785,13 @@ static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
if (!prealloc)
htab_elem_set_ptr(l_new, key_size, pptr);
- } else {
+ } else if (fd_htab_map_needs_adjust(htab)) {
+ size = round_up(size, 8);
memcpy(l_new->key + round_up(key_size, 8), value, size);
+ } else {
+ copy_map_value(&htab->map,
+ l_new->key + round_up(key_size, 8),
+ value);
}
l_new->hash = hash;
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index a74972b07e74..e1d6aefbab50 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -221,6 +221,63 @@ const struct bpf_func_proto bpf_get_current_comm_proto = {
.arg2_type = ARG_CONST_SIZE,
};
+#ifndef CONFIG_QUEUED_SPINLOCKS
+struct dumb_spin_lock {
+ atomic_t val;
+};
+#endif
+
+notrace BPF_CALL_1(bpf_spin_lock, struct bpf_spin_lock *, lock)
+{
+#if defined(CONFIG_SMP)
+#ifdef CONFIG_QUEUED_SPINLOCKS
+ struct qspinlock *qlock = (void *)lock;
+
+ BUILD_BUG_ON(sizeof(*qlock) != sizeof(*lock));
+ queued_spin_lock(qlock);
+#else
+ struct dumb_spin_lock *qlock = (void *)lock;
+
+ BUILD_BUG_ON(sizeof(*qlock) != sizeof(*lock));
+ do {
+ while (atomic_read(&qlock->val) != 0)
+ cpu_relax();
+ } while (atomic_cmpxchg(&qlock->val, 0, 1) != 0);
+#endif
+#endif
+ return 0;
+}
+
+const struct bpf_func_proto bpf_spin_lock_proto = {
+ .func = bpf_spin_lock,
+ .gpl_only = false,
+ .ret_type = RET_VOID,
+ .arg1_type = ARG_PTR_TO_SPIN_LOCK,
+};
+
+notrace BPF_CALL_1(bpf_spin_unlock, struct bpf_spin_lock *, lock)
+{
+#if defined(CONFIG_SMP)
+#ifdef CONFIG_QUEUED_SPINLOCKS
+ struct qspinlock *qlock = (void *)lock;
+
+ queued_spin_unlock(qlock);
+#else
+ struct dumb_spin_lock *qlock = (void *)lock;
+
+ atomic_set_release(&qlock->val, 0);
+#endif
+#endif
+ return 0;
+}
+
+const struct bpf_func_proto bpf_spin_unlock_proto = {
+ .func = bpf_spin_unlock,
+ .gpl_only = false,
+ .ret_type = RET_VOID,
+ .arg1_type = ARG_PTR_TO_SPIN_LOCK,
+};
+
#ifdef CONFIG_CGROUPS
BPF_CALL_0(bpf_get_current_cgroup_id)
{
diff --git a/kernel/bpf/map_in_map.c b/kernel/bpf/map_in_map.c
index 99d243e1ad6e..920eff1b677b 100644
--- a/kernel/bpf/map_in_map.c
+++ b/kernel/bpf/map_in_map.c
@@ -36,6 +36,11 @@ struct bpf_map *bpf_map_meta_alloc(int inner_map_ufd)
return ERR_PTR(-EINVAL);
}
+ if (map_value_has_spin_lock(inner_map)) {
+ fdput(f);
+ return ERR_PTR(-ENOTSUPP);
+ }
+
inner_map_meta = kzalloc(sizeof(*inner_map_meta), GFP_USER);
if (!inner_map_meta) {
fdput(f);
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index b155cd17c1bd..ebf0a673cb83 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -463,7 +463,7 @@ int map_check_no_btf(const struct bpf_map *map,
return -ENOTSUPP;
}
-static int map_check_btf(const struct bpf_map *map, const struct btf *btf,
+static int map_check_btf(struct bpf_map *map, const struct btf *btf,
u32 btf_key_id, u32 btf_value_id)
{
const struct btf_type *key_type, *value_type;
@@ -478,6 +478,21 @@ static int map_check_btf(const struct bpf_map *map, const struct btf *btf,
if (!value_type || value_size != map->value_size)
return -EINVAL;
+ map->spin_lock_off = btf_find_spin_lock(btf, value_type);
+
+ if (map_value_has_spin_lock(map)) {
+ if (map->map_type != BPF_MAP_TYPE_HASH &&
+ map->map_type != BPF_MAP_TYPE_ARRAY)
+ return -ENOTSUPP;
+ if (map->spin_lock_off + sizeof(struct bpf_spin_lock) >
+ map->value_size) {
+ WARN_ONCE(1,
+ "verifier bug spin_lock_off %d value_size %d\n",
+ map->spin_lock_off, map->value_size);
+ return -EFAULT;
+ }
+ }
+
if (map->ops->map_check_btf)
ret = map->ops->map_check_btf(map, btf, key_type, value_type);
@@ -542,6 +557,8 @@ static int map_create(union bpf_attr *attr)
map->btf = btf;
map->btf_key_type_id = attr->btf_key_type_id;
map->btf_value_type_id = attr->btf_value_type_id;
+ } else {
+ map->spin_lock_off = -EINVAL;
}
err = security_bpf_map_alloc(map);
@@ -740,7 +757,7 @@ static int map_lookup_elem(union bpf_attr *attr)
err = -ENOENT;
} else {
err = 0;
- memcpy(value, ptr, value_size);
+ copy_map_value(map, value, ptr);
}
rcu_read_unlock();
}
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 8c1c21cd50b4..b6af9d2cb236 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -213,6 +213,7 @@ struct bpf_call_arg_meta {
s64 msize_smax_value;
u64 msize_umax_value;
int ptr_id;
+ int func_id;
};
static DEFINE_MUTEX(bpf_verifier_lock);
@@ -351,6 +352,12 @@ static bool reg_is_refcounted(const struct bpf_reg_state *reg)
return type_is_refcounted(reg->type);
}
+static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg)
+{
+ return reg->type == PTR_TO_MAP_VALUE &&
+ map_value_has_spin_lock(reg->map_ptr);
+}
+
static bool reg_is_refcounted_or_null(const struct bpf_reg_state *reg)
{
return type_is_refcounted_or_null(reg->type);
@@ -712,6 +719,7 @@ static int copy_verifier_state(struct bpf_verifier_state *dst_state,
}
dst_state->speculative = src->speculative;
dst_state->curframe = src->curframe;
+ dst_state->active_spin_lock = src->active_spin_lock;
for (i = 0; i <= src->curframe; i++) {
dst = dst_state->frame[i];
if (!dst) {
@@ -1483,6 +1491,21 @@ static int check_map_access(struct bpf_verifier_env *env, u32 regno,
if (err)
verbose(env, "R%d max value is outside of the array range\n",
regno);
+
+ if (map_value_has_spin_lock(reg->map_ptr)) {
+ u32 lock = reg->map_ptr->spin_lock_off;
+
+ /* if any part of struct bpf_spin_lock can be touched by
+ * load/store reject this program
+ */
+ if ((reg->smin_value + off <= lock &&
+ lock < reg->umax_value + off + size) ||
+ (reg->smin_value + off < lock + sizeof(struct bpf_spin_lock) &&
+ lock + sizeof(struct bpf_spin_lock) <= reg->umax_value + off + size)) {
+ verbose(env, "bpf_spin_lock cannot be accessed directly by load/store\n");
+ return -EACCES;
+ }
+ }
return err;
}
@@ -2192,6 +2215,91 @@ static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
}
}
+/* Implementation details:
+ * bpf_map_lookup returns PTR_TO_MAP_VALUE_OR_NULL
+ * Two bpf_map_lookups (even with the same key) will have different reg->id.
+ * For traditional PTR_TO_MAP_VALUE the verifier clears reg->id after
+ * value_or_null->value transition, since the verifier only cares about
+ * the range of access to valid map value pointer and doesn't care about actual
+ * address of the map element.
+ * For maps with 'struct bpf_spin_lock' inside map value the verifier keeps
+ * reg->id > 0 after value_or_null->value transition. By doing so
+ * two bpf_map_lookups will be considered two different pointers that
+ * point to different bpf_spin_locks.
+ * The verifier allows taking only one bpf_spin_lock at a time to avoid
+ * dead-locks.
+ * Since only one bpf_spin_lock is allowed the checks are simpler than
+ * reg_is_refcounted() logic. The verifier needs to remember only
+ * one spin_lock instead of array of acquired_refs.
+ * cur_state->active_spin_lock remembers which map value element got locked
+ * and clears it after bpf_spin_unlock.
+ */
+static int process_spin_lock(struct bpf_verifier_env *env, int regno,
+ bool is_lock)
+{
+ struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
+ struct bpf_verifier_state *cur = env->cur_state;
+ bool is_const = tnum_is_const(reg->var_off);
+ struct bpf_map *map = reg->map_ptr;
+ u64 val = reg->var_off.value;
+
+ if (reg->type != PTR_TO_MAP_VALUE) {
+ verbose(env, "R%d is not a pointer to map_value\n", regno);
+ return -EINVAL;
+ }
+ if (!is_const) {
+ verbose(env,
+ "R%d doesn't have constant offset. bpf_spin_lock has to be at the constant offset\n",
+ regno);
+ return -EINVAL;
+ }
+ if (!map->btf) {
+ verbose(env,
+ "map '%s' has to have BTF in order to use bpf_spin_lock\n",
+ map->name);
+ return -EINVAL;
+ }
+ if (!map_value_has_spin_lock(map)) {
+ if (map->spin_lock_off == -E2BIG)
+ verbose(env,
+ "map '%s' has more than one 'struct bpf_spin_lock'\n",
+ map->name);
+ else if (map->spin_lock_off == -ENOENT)
+ verbose(env,
+ "map '%s' doesn't have 'struct bpf_spin_lock'\n",
+ map->name);
+ else
+ verbose(env,
+ "map '%s' is not a struct type or bpf_spin_lock is mangled\n",
+ map->name);
+ return -EINVAL;
+ }
+ if (map->spin_lock_off != val + reg->off) {
+ verbose(env, "off %lld doesn't point to 'struct bpf_spin_lock'\n",
+ val + reg->off);
+ return -EINVAL;
+ }
+ if (is_lock) {
+ if (cur->active_spin_lock) {
+ verbose(env,
+ "Locking two bpf_spin_locks are not allowed\n");
+ return -EINVAL;
+ }
+ cur->active_spin_lock = reg->id;
+ } else {
+ if (!cur->active_spin_lock) {
+ verbose(env, "bpf_spin_unlock without taking a lock\n");
+ return -EINVAL;
+ }
+ if (cur->active_spin_lock != reg->id) {
+ verbose(env, "bpf_spin_unlock of different lock\n");
+ return -EINVAL;
+ }
+ cur->active_spin_lock = 0;
+ }
+ return 0;
+}
+
static bool arg_type_is_mem_ptr(enum bpf_arg_type type)
{
return type == ARG_PTR_TO_MEM ||
@@ -2268,6 +2376,17 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 regno,
return -EFAULT;
}
meta->ptr_id = reg->id;
+ } else if (arg_type == ARG_PTR_TO_SPIN_LOCK) {
+ if (meta->func_id == BPF_FUNC_spin_lock) {
+ if (process_spin_lock(env, regno, true))
+ return -EACCES;
+ } else if (meta->func_id == BPF_FUNC_spin_unlock) {
+ if (process_spin_lock(env, regno, false))
+ return -EACCES;
+ } else {
+ verbose(env, "verifier internal error\n");
+ return -EFAULT;
+ }
} else if (arg_type_is_mem_ptr(arg_type)) {
expected_type = PTR_TO_STACK;
/* One exception here. In case function allows for NULL to be
@@ -2887,6 +3006,7 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn
return err;
}
+ meta.func_id = func_id;
/* check args */
err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &meta);
if (err)
@@ -4473,7 +4593,8 @@ static void mark_ptr_or_null_reg(struct bpf_func_state *state,
} else if (reg->type == PTR_TO_SOCKET_OR_NULL) {
reg->type = PTR_TO_SOCKET;
}
- if (is_null || !reg_is_refcounted(reg)) {
+ if (is_null || !(reg_is_refcounted(reg) ||
+ reg_may_point_to_spin_lock(reg))) {
/* We don't need id from this point onwards anymore,
* thus we should better reset it, so that state
* pruning has chances to take effect.
@@ -4871,6 +4992,11 @@ static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
return err;
}
+ if (env->cur_state->active_spin_lock) {
+ verbose(env, "BPF_LD_[ABS|IND] cannot be used inside bpf_spin_lock-ed region\n");
+ return -EINVAL;
+ }
+
if (regs[BPF_REG_6].type != PTR_TO_CTX) {
verbose(env,
"at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
@@ -5607,8 +5733,11 @@ static bool regsafe(struct bpf_reg_state *rold, struct bpf_reg_state *rcur,
case PTR_TO_MAP_VALUE:
/* If the new min/max/var_off satisfy the old ones and
* everything else matches, we are OK.
- * We don't care about the 'id' value, because nothing
- * uses it for PTR_TO_MAP_VALUE (only for ..._OR_NULL)
+ * 'id' is not compared, since it's only used for maps with
+ * bpf_spin_lock inside map element and in such cases if
+ * the rest of the prog is valid for one map element then
+ * it's valid for all map elements regardless of the key
+ * used in bpf_map_lookup()
*/
return memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)) == 0 &&
range_within(rold, rcur) &&
@@ -5811,6 +5940,9 @@ static bool states_equal(struct bpf_verifier_env *env,
if (old->speculative && !cur->speculative)
return false;
+ if (old->active_spin_lock != cur->active_spin_lock)
+ return false;
+
/* for states to be equal callsites have to be the same
* and all frame states need to be equivalent
*/
@@ -6229,6 +6361,12 @@ static int do_check(struct bpf_verifier_env *env)
return -EINVAL;
}
+ if (env->cur_state->active_spin_lock &&
+ (insn->src_reg == BPF_PSEUDO_CALL ||
+ insn->imm != BPF_FUNC_spin_unlock)) {
+ verbose(env, "function calls are not allowed while holding a lock\n");
+ return -EINVAL;
+ }
if (insn->src_reg == BPF_PSEUDO_CALL)
err = check_func_call(env, insn, &env->insn_idx);
else
@@ -6259,6 +6397,11 @@ static int do_check(struct bpf_verifier_env *env)
return -EINVAL;
}
+ if (env->cur_state->active_spin_lock) {
+ verbose(env, "bpf_spin_unlock is missing\n");
+ return -EINVAL;
+ }
+
if (state->curframe) {
/* exit from nested function */
env->prev_insn_idx = env->insn_idx;
@@ -6356,6 +6499,19 @@ static int check_map_prealloc(struct bpf_map *map)
!(map->map_flags & BPF_F_NO_PREALLOC);
}
+static bool is_tracing_prog_type(enum bpf_prog_type type)
+{
+ switch (type) {
+ case BPF_PROG_TYPE_KPROBE:
+ case BPF_PROG_TYPE_TRACEPOINT:
+ case BPF_PROG_TYPE_PERF_EVENT:
+ case BPF_PROG_TYPE_RAW_TRACEPOINT:
+ return true;
+ default:
+ return false;
+ }
+}
+
static int check_map_prog_compatibility(struct bpf_verifier_env *env,
struct bpf_map *map,
struct bpf_prog *prog)
@@ -6378,6 +6534,13 @@ static int check_map_prog_compatibility(struct bpf_verifier_env *env,
}
}
+ if ((is_tracing_prog_type(prog->type) ||
+ prog->type == BPF_PROG_TYPE_SOCKET_FILTER) &&
+ map_value_has_spin_lock(map)) {
+ verbose(env, "tracing progs cannot use bpf_spin_lock yet\n");
+ return -EINVAL;
+ }
+
if ((bpf_prog_is_dev_bound(prog->aux) || bpf_map_is_dev_bound(map)) &&
!bpf_offload_prog_map_match(prog, map)) {
verbose(env, "offload device mismatch between prog and map\n");
diff --git a/net/core/filter.c b/net/core/filter.c
index 8e587dd1da20..9cde260d5022 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5306,10 +5306,20 @@ bpf_base_func_proto(enum bpf_func_id func_id)
return &bpf_tail_call_proto;
case BPF_FUNC_ktime_get_ns:
return &bpf_ktime_get_ns_proto;
+ default:
+ break;
+ }
+
+ if (!capable(CAP_SYS_ADMIN))
+ return NULL;
+
+ switch (func_id) {
+ case BPF_FUNC_spin_lock:
+ return &bpf_spin_lock_proto;
+ case BPF_FUNC_spin_unlock:
+ return &bpf_spin_unlock_proto;
case BPF_FUNC_trace_printk:
- if (capable(CAP_SYS_ADMIN))
- return bpf_get_trace_printk_proto();
- /* else: fall through */
+ return bpf_get_trace_printk_proto();
default:
return NULL;
}
--
2.20.0
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