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authorDavid S. Miller <davem@davemloft.net>2018-01-10 11:17:21 -0500
committerDavid S. Miller <davem@davemloft.net>2018-01-10 11:17:21 -0500
commit661e4e33a984fbd05e6b573ce4bb639ca699c130 (patch)
tree421a7e3828bc73daae816e5cd8aa91403aa5a12d
parent4512c43eac7e007d982e7ea45152ea6f3f4d1921 (diff)
parent290af86629b25ffd1ed6232c4e9107da031705cb (diff)
Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf
Daniel Borkmann says: ==================== pull-request: bpf 2018-01-09 The following pull-request contains BPF updates for your *net* tree. The main changes are: 1) Prevent out-of-bounds speculation in BPF maps by masking the index after bounds checks in order to fix spectre v1, and add an option BPF_JIT_ALWAYS_ON into Kconfig that allows for removing the BPF interpreter from the kernel in favor of JIT-only mode to make spectre v2 harder, from Alexei. 2) Remove false sharing of map refcount with max_entries which was used in spectre v1, from Daniel. 3) Add a missing NULL psock check in sockmap in order to fix a race, from John. 4) Fix test_align BPF selftest case since a recent change in verifier rejects the bit-wise arithmetic on pointers earlier but test_align update was missing, from Alexei. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/linux/bpf.h26
-rw-r--r--init/Kconfig7
-rw-r--r--kernel/bpf/arraymap.c47
-rw-r--r--kernel/bpf/core.c19
-rw-r--r--kernel/bpf/sockmap.c11
-rw-r--r--kernel/bpf/verifier.c36
-rw-r--r--lib/test_bpf.c11
-rw-r--r--net/core/filter.c6
-rw-r--r--net/core/sysctl_net_core.c6
-rw-r--r--net/socket.c9
-rw-r--r--tools/testing/selftests/bpf/test_align.c22
11 files changed, 150 insertions, 50 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index b63a592ad29d..0b25cf87b6d6 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -43,7 +43,14 @@ struct bpf_map_ops {
};
struct bpf_map {
- atomic_t refcnt;
+ /* 1st cacheline with read-mostly members of which some
+ * are also accessed in fast-path (e.g. ops, max_entries).
+ */
+ const struct bpf_map_ops *ops ____cacheline_aligned;
+ struct bpf_map *inner_map_meta;
+#ifdef CONFIG_SECURITY
+ void *security;
+#endif
enum bpf_map_type map_type;
u32 key_size;
u32 value_size;
@@ -52,15 +59,17 @@ struct bpf_map {
u32 pages;
u32 id;
int numa_node;
- struct user_struct *user;
- const struct bpf_map_ops *ops;
- struct work_struct work;
+ bool unpriv_array;
+ /* 7 bytes hole */
+
+ /* 2nd cacheline with misc members to avoid false sharing
+ * particularly with refcounting.
+ */
+ struct user_struct *user ____cacheline_aligned;
+ atomic_t refcnt;
atomic_t usercnt;
- struct bpf_map *inner_map_meta;
+ struct work_struct work;
char name[BPF_OBJ_NAME_LEN];
-#ifdef CONFIG_SECURITY
- void *security;
-#endif
};
/* function argument constraints */
@@ -221,6 +230,7 @@ struct bpf_prog_aux {
struct bpf_array {
struct bpf_map map;
u32 elem_size;
+ u32 index_mask;
/* 'ownership' of prog_array is claimed by the first program that
* is going to use this map or by the first program which FD is stored
* in the map to make sure that all callers and callees have the same
diff --git a/init/Kconfig b/init/Kconfig
index 690a381adee0..19a6b845d834 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1396,6 +1396,13 @@ config BPF_SYSCALL
Enable the bpf() system call that allows to manipulate eBPF
programs and maps via file descriptors.
+config BPF_JIT_ALWAYS_ON
+ bool "Permanently enable BPF JIT and remove BPF interpreter"
+ depends on BPF_SYSCALL && HAVE_EBPF_JIT && BPF_JIT
+ help
+ Enables BPF JIT and removes BPF interpreter to avoid
+ speculative execution of BPF instructions by the interpreter
+
config USERFAULTFD
bool "Enable userfaultfd() system call"
select ANON_INODES
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 7c25426d3cf5..aaa319848e7d 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -53,9 +53,10 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr)
{
bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;
int numa_node = bpf_map_attr_numa_node(attr);
+ u32 elem_size, index_mask, max_entries;
+ bool unpriv = !capable(CAP_SYS_ADMIN);
struct bpf_array *array;
u64 array_size;
- u32 elem_size;
/* check sanity of attributes */
if (attr->max_entries == 0 || attr->key_size != 4 ||
@@ -72,11 +73,20 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr)
elem_size = round_up(attr->value_size, 8);
+ max_entries = attr->max_entries;
+ index_mask = roundup_pow_of_two(max_entries) - 1;
+
+ if (unpriv)
+ /* round up array size to nearest power of 2,
+ * since cpu will speculate within index_mask limits
+ */
+ max_entries = index_mask + 1;
+
array_size = sizeof(*array);
if (percpu)
- array_size += (u64) attr->max_entries * sizeof(void *);
+ array_size += (u64) max_entries * sizeof(void *);
else
- array_size += (u64) attr->max_entries * elem_size;
+ array_size += (u64) max_entries * elem_size;
/* make sure there is no u32 overflow later in round_up() */
if (array_size >= U32_MAX - PAGE_SIZE)
@@ -86,6 +96,8 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr)
array = bpf_map_area_alloc(array_size, numa_node);
if (!array)
return ERR_PTR(-ENOMEM);
+ array->index_mask = index_mask;
+ array->map.unpriv_array = unpriv;
/* copy mandatory map attributes */
array->map.map_type = attr->map_type;
@@ -121,12 +133,13 @@ static void *array_map_lookup_elem(struct bpf_map *map, void *key)
if (unlikely(index >= array->map.max_entries))
return NULL;
- return array->value + array->elem_size * index;
+ return array->value + array->elem_size * (index & array->index_mask);
}
/* emit BPF instructions equivalent to C code of array_map_lookup_elem() */
static u32 array_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
{
+ struct bpf_array *array = container_of(map, struct bpf_array, map);
struct bpf_insn *insn = insn_buf;
u32 elem_size = round_up(map->value_size, 8);
const int ret = BPF_REG_0;
@@ -135,7 +148,12 @@ static u32 array_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
*insn++ = BPF_ALU64_IMM(BPF_ADD, map_ptr, offsetof(struct bpf_array, value));
*insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);
- *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 3);
+ if (map->unpriv_array) {
+ *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 4);
+ *insn++ = BPF_ALU32_IMM(BPF_AND, ret, array->index_mask);
+ } else {
+ *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 3);
+ }
if (is_power_of_2(elem_size)) {
*insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(elem_size));
@@ -157,7 +175,7 @@ static void *percpu_array_map_lookup_elem(struct bpf_map *map, void *key)
if (unlikely(index >= array->map.max_entries))
return NULL;
- return this_cpu_ptr(array->pptrs[index]);
+ return this_cpu_ptr(array->pptrs[index & array->index_mask]);
}
int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value)
@@ -177,7 +195,7 @@ int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value)
*/
size = round_up(map->value_size, 8);
rcu_read_lock();
- pptr = array->pptrs[index];
+ pptr = array->pptrs[index & array->index_mask];
for_each_possible_cpu(cpu) {
bpf_long_memcpy(value + off, per_cpu_ptr(pptr, cpu), size);
off += size;
@@ -225,10 +243,11 @@ static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
return -EEXIST;
if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
- memcpy(this_cpu_ptr(array->pptrs[index]),
+ memcpy(this_cpu_ptr(array->pptrs[index & array->index_mask]),
value, map->value_size);
else
- memcpy(array->value + array->elem_size * index,
+ memcpy(array->value +
+ array->elem_size * (index & array->index_mask),
value, map->value_size);
return 0;
}
@@ -262,7 +281,7 @@ int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value,
*/
size = round_up(map->value_size, 8);
rcu_read_lock();
- pptr = array->pptrs[index];
+ pptr = array->pptrs[index & array->index_mask];
for_each_possible_cpu(cpu) {
bpf_long_memcpy(per_cpu_ptr(pptr, cpu), value + off, size);
off += size;
@@ -613,6 +632,7 @@ static void *array_of_map_lookup_elem(struct bpf_map *map, void *key)
static u32 array_of_map_gen_lookup(struct bpf_map *map,
struct bpf_insn *insn_buf)
{
+ struct bpf_array *array = container_of(map, struct bpf_array, map);
u32 elem_size = round_up(map->value_size, 8);
struct bpf_insn *insn = insn_buf;
const int ret = BPF_REG_0;
@@ -621,7 +641,12 @@ static u32 array_of_map_gen_lookup(struct bpf_map *map,
*insn++ = BPF_ALU64_IMM(BPF_ADD, map_ptr, offsetof(struct bpf_array, value));
*insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);
- *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5);
+ if (map->unpriv_array) {
+ *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 6);
+ *insn++ = BPF_ALU32_IMM(BPF_AND, ret, array->index_mask);
+ } else {
+ *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5);
+ }
if (is_power_of_2(elem_size))
*insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(elem_size));
else
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 86b50aa26ee8..51ec2dda7f08 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -767,6 +767,7 @@ noinline u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
}
EXPORT_SYMBOL_GPL(__bpf_call_base);
+#ifndef CONFIG_BPF_JIT_ALWAYS_ON
/**
* __bpf_prog_run - run eBPF program on a given context
* @ctx: is the data we are operating on
@@ -1317,6 +1318,14 @@ EVAL6(PROG_NAME_LIST, 224, 256, 288, 320, 352, 384)
EVAL4(PROG_NAME_LIST, 416, 448, 480, 512)
};
+#else
+static unsigned int __bpf_prog_ret0(const void *ctx,
+ const struct bpf_insn *insn)
+{
+ return 0;
+}
+#endif
+
bool bpf_prog_array_compatible(struct bpf_array *array,
const struct bpf_prog *fp)
{
@@ -1364,9 +1373,13 @@ static int bpf_check_tail_call(const struct bpf_prog *fp)
*/
struct bpf_prog *bpf_prog_select_runtime(struct bpf_prog *fp, int *err)
{
+#ifndef CONFIG_BPF_JIT_ALWAYS_ON
u32 stack_depth = max_t(u32, fp->aux->stack_depth, 1);
fp->bpf_func = interpreters[(round_up(stack_depth, 32) / 32) - 1];
+#else
+ fp->bpf_func = __bpf_prog_ret0;
+#endif
/* eBPF JITs can rewrite the program in case constant
* blinding is active. However, in case of error during
@@ -1376,6 +1389,12 @@ struct bpf_prog *bpf_prog_select_runtime(struct bpf_prog *fp, int *err)
*/
if (!bpf_prog_is_dev_bound(fp->aux)) {
fp = bpf_int_jit_compile(fp);
+#ifdef CONFIG_BPF_JIT_ALWAYS_ON
+ if (!fp->jited) {
+ *err = -ENOTSUPP;
+ return fp;
+ }
+#endif
} else {
*err = bpf_prog_offload_compile(fp);
if (*err)
diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c
index 5ee2e41893d9..1712d319c2d8 100644
--- a/kernel/bpf/sockmap.c
+++ b/kernel/bpf/sockmap.c
@@ -591,8 +591,15 @@ static void sock_map_free(struct bpf_map *map)
write_lock_bh(&sock->sk_callback_lock);
psock = smap_psock_sk(sock);
- smap_list_remove(psock, &stab->sock_map[i]);
- smap_release_sock(psock, sock);
+ /* This check handles a racing sock event that can get the
+ * sk_callback_lock before this case but after xchg happens
+ * causing the refcnt to hit zero and sock user data (psock)
+ * to be null and queued for garbage collection.
+ */
+ if (likely(psock)) {
+ smap_list_remove(psock, &stab->sock_map[i]);
+ smap_release_sock(psock, sock);
+ }
write_unlock_bh(&sock->sk_callback_lock);
}
rcu_read_unlock();
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 04b24876cd23..b414d6b2d470 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1729,6 +1729,13 @@ static int check_call(struct bpf_verifier_env *env, int func_id, int insn_idx)
err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &meta);
if (err)
return err;
+ if (func_id == BPF_FUNC_tail_call) {
+ if (meta.map_ptr == NULL) {
+ verbose(env, "verifier bug\n");
+ return -EINVAL;
+ }
+ env->insn_aux_data[insn_idx].map_ptr = meta.map_ptr;
+ }
err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &meta);
if (err)
return err;
@@ -4456,6 +4463,35 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env)
*/
insn->imm = 0;
insn->code = BPF_JMP | BPF_TAIL_CALL;
+
+ /* instead of changing every JIT dealing with tail_call
+ * emit two extra insns:
+ * if (index >= max_entries) goto out;
+ * index &= array->index_mask;
+ * to avoid out-of-bounds cpu speculation
+ */
+ map_ptr = env->insn_aux_data[i + delta].map_ptr;
+ if (map_ptr == BPF_MAP_PTR_POISON) {
+ verbose(env, "tail_call obusing map_ptr\n");
+ return -EINVAL;
+ }
+ if (!map_ptr->unpriv_array)
+ continue;
+ insn_buf[0] = BPF_JMP_IMM(BPF_JGE, BPF_REG_3,
+ map_ptr->max_entries, 2);
+ insn_buf[1] = BPF_ALU32_IMM(BPF_AND, BPF_REG_3,
+ container_of(map_ptr,
+ struct bpf_array,
+ map)->index_mask);
+ insn_buf[2] = *insn;
+ cnt = 3;
+ new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
+ if (!new_prog)
+ return -ENOMEM;
+
+ delta += cnt - 1;
+ env->prog = prog = new_prog;
+ insn = new_prog->insnsi + i + delta;
continue;
}
diff --git a/lib/test_bpf.c b/lib/test_bpf.c
index 9e9748089270..f369889e521d 100644
--- a/lib/test_bpf.c
+++ b/lib/test_bpf.c
@@ -6250,9 +6250,8 @@ static struct bpf_prog *generate_filter(int which, int *err)
return NULL;
}
}
- /* We don't expect to fail. */
if (*err) {
- pr_cont("FAIL to attach err=%d len=%d\n",
+ pr_cont("FAIL to prog_create err=%d len=%d\n",
*err, fprog.len);
return NULL;
}
@@ -6276,6 +6275,10 @@ static struct bpf_prog *generate_filter(int which, int *err)
* checks.
*/
fp = bpf_prog_select_runtime(fp, err);
+ if (*err) {
+ pr_cont("FAIL to select_runtime err=%d\n", *err);
+ return NULL;
+ }
break;
}
@@ -6461,8 +6464,8 @@ static __init int test_bpf(void)
pass_cnt++;
continue;
}
-
- return err;
+ err_cnt++;
+ continue;
}
pr_cont("jited:%u ", fp->jited);
diff --git a/net/core/filter.c b/net/core/filter.c
index 6a85e67fafce..d339ef170df6 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1054,11 +1054,9 @@ static struct bpf_prog *bpf_migrate_filter(struct bpf_prog *fp)
*/
goto out_err_free;
- /* We are guaranteed to never error here with cBPF to eBPF
- * transitions, since there's no issue with type compatibility
- * checks on program arrays.
- */
fp = bpf_prog_select_runtime(fp, &err);
+ if (err)
+ goto out_err_free;
kfree(old_prog);
return fp;
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index cbc3dde4cfcc..a47ad6cd41c0 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -325,7 +325,13 @@ static struct ctl_table net_core_table[] = {
.data = &bpf_jit_enable,
.maxlen = sizeof(int),
.mode = 0644,
+#ifndef CONFIG_BPF_JIT_ALWAYS_ON
.proc_handler = proc_dointvec
+#else
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &one,
+ .extra2 = &one,
+#endif
},
# ifdef CONFIG_HAVE_EBPF_JIT
{
diff --git a/net/socket.c b/net/socket.c
index 05f361faec45..78acd6ce74c7 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2619,6 +2619,15 @@ out_fs:
core_initcall(sock_init); /* early initcall */
+static int __init jit_init(void)
+{
+#ifdef CONFIG_BPF_JIT_ALWAYS_ON
+ bpf_jit_enable = 1;
+#endif
+ return 0;
+}
+pure_initcall(jit_init);
+
#ifdef CONFIG_PROC_FS
void socket_seq_show(struct seq_file *seq)
{
diff --git a/tools/testing/selftests/bpf/test_align.c b/tools/testing/selftests/bpf/test_align.c
index 8591c89c0828..471bbbdb94db 100644
--- a/tools/testing/selftests/bpf/test_align.c
+++ b/tools/testing/selftests/bpf/test_align.c
@@ -474,27 +474,7 @@ static struct bpf_align_test tests[] = {
.result = REJECT,
.matches = {
{4, "R5=pkt(id=0,off=0,r=0,imm=0)"},
- /* ptr & 0x40 == either 0 or 0x40 */
- {5, "R5=inv(id=0,umax_value=64,var_off=(0x0; 0x40))"},
- /* ptr << 2 == unknown, (4n) */
- {7, "R5=inv(id=0,smax_value=9223372036854775804,umax_value=18446744073709551612,var_off=(0x0; 0xfffffffffffffffc))"},
- /* (4n) + 14 == (4n+2). We blow our bounds, because
- * the add could overflow.
- */
- {8, "R5=inv(id=0,var_off=(0x2; 0xfffffffffffffffc))"},
- /* Checked s>=0 */
- {10, "R5=inv(id=0,umin_value=2,umax_value=9223372036854775806,var_off=(0x2; 0x7ffffffffffffffc))"},
- /* packet pointer + nonnegative (4n+2) */
- {12, "R6=pkt(id=1,off=0,r=0,umin_value=2,umax_value=9223372036854775806,var_off=(0x2; 0x7ffffffffffffffc))"},
- {14, "R4=pkt(id=1,off=4,r=0,umin_value=2,umax_value=9223372036854775806,var_off=(0x2; 0x7ffffffffffffffc))"},
- /* NET_IP_ALIGN + (4n+2) == (4n), alignment is fine.
- * We checked the bounds, but it might have been able
- * to overflow if the packet pointer started in the
- * upper half of the address space.
- * So we did not get a 'range' on R6, and the access
- * attempt will fail.
- */
- {16, "R6=pkt(id=1,off=0,r=0,umin_value=2,umax_value=9223372036854775806,var_off=(0x2; 0x7ffffffffffffffc))"},
+ /* R5 bitwise operator &= on pointer prohibited */
}
},
{