From: Andrey Ignatov <rdna@fb.com>
To: <netdev@vger.kernel.org>
Cc: Andrey Ignatov <rdna@fb.com>, <ast@kernel.org>,
<daniel@iogearbox.net>, <guro@fb.com>, <kernel-team@fb.com>,
Luis Chamberlain <mcgrof@kernel.org>,
Kees Cook <keescook@chromium.org>,
Alexey Dobriyan <adobriyan@gmail.com>,
<linux-kernel@vger.kernel.org>, <linux-fsdevel@vger.kernel.org>
Subject: [PATCH v2 bpf-next 15/21] bpf: Introduce ARG_PTR_TO_{INT,LONG} arg types
Date: Mon, 25 Mar 2019 17:43:41 -0700 [thread overview]
Message-ID: <7acb1bc919ec410210c863c5418d13e818f7a651.1553560621.git.rdna@fb.com> (raw)
In-Reply-To: <cover.1553560620.git.rdna@fb.com>
Currently the way to pass result from BPF helper to BPF program is to
provide memory area defined by pointer and size: func(void *, size_t).
It works great for generic use-case, but for simple types, such as int,
it's overkill and consumes two arguments when it could use just one.
Introduce new argument types ARG_PTR_TO_INT and ARG_PTR_TO_LONG to be
able to pass result from helper to program via pointer to int and long
correspondingly: func(int *) or func(long *).
New argument types are similar to ARG_PTR_TO_MEM with the following
differences:
* they don't require corresponding ARG_CONST_SIZE argument, predefined
access sizes are used instead (32bit for int, 64bit for long);
* it's possible to use more than one such an argument in a helper;
* provided pointers have to be aligned.
It's easy to introduce similar ARG_PTR_TO_CHAR and ARG_PTR_TO_SHORT
argument types. It's not done due to lack of use-case though.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
---
include/linux/bpf.h | 2 ++
kernel/bpf/verifier.c | 29 +++++++++++++++++++++++++++++
2 files changed, 31 insertions(+)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index f62897198844..ce53d4350946 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -195,6 +195,8 @@ enum bpf_arg_type {
ARG_ANYTHING, /* any (initialized) argument is ok */
ARG_PTR_TO_SPIN_LOCK, /* pointer to bpf_spin_lock */
ARG_PTR_TO_SOCK_COMMON, /* pointer to sock_common */
+ ARG_PTR_TO_INT, /* pointer to int */
+ ARG_PTR_TO_LONG, /* pointer to long */
};
/* type of values returned from helper functions */
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 34e51be862e2..477b61a6c203 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2344,6 +2344,22 @@ static bool arg_type_is_mem_size(enum bpf_arg_type type)
type == ARG_CONST_SIZE_OR_ZERO;
}
+static bool arg_type_is_int_ptr(enum bpf_arg_type type)
+{
+ return type == ARG_PTR_TO_INT ||
+ type == ARG_PTR_TO_LONG;
+}
+
+static int int_ptr_type_to_size(enum bpf_arg_type type)
+{
+ if (type == ARG_PTR_TO_INT)
+ return sizeof(u32);
+ else if (type == ARG_PTR_TO_LONG)
+ return sizeof(u64);
+
+ return -EINVAL;
+}
+
static int check_func_arg(struct bpf_verifier_env *env, u32 regno,
enum bpf_arg_type arg_type,
struct bpf_call_arg_meta *meta)
@@ -2436,6 +2452,12 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 regno,
type != expected_type)
goto err_type;
meta->raw_mode = arg_type == ARG_PTR_TO_UNINIT_MEM;
+ } else if (arg_type_is_int_ptr(arg_type)) {
+ expected_type = PTR_TO_STACK;
+ if (!type_is_pkt_pointer(type) &&
+ type != PTR_TO_MAP_VALUE &&
+ type != expected_type)
+ goto err_type;
} else {
verbose(env, "unsupported arg_type %d\n", arg_type);
return -EFAULT;
@@ -2517,6 +2539,13 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 regno,
err = check_helper_mem_access(env, regno - 1,
reg->umax_value,
zero_size_allowed, meta);
+ } else if (arg_type_is_int_ptr(arg_type)) {
+ int size = int_ptr_type_to_size(arg_type);
+
+ err = check_helper_mem_access(env, regno, size, false, meta);
+ if (err)
+ return err;
+ err = check_ptr_alignment(env, reg, 0, size, true);
}
return err;
--
2.17.1
next prev parent reply other threads:[~2019-03-26 0:48 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-26 0:43 [PATCH v2 bpf-next 00/21] bpf: Sysctl hook Andrey Ignatov
2019-03-26 0:43 ` [PATCH v2 bpf-next 01/21] bpf: Add base proto function for cgroup-bpf programs Andrey Ignatov
2019-03-26 0:43 ` [PATCH v2 bpf-next 02/21] bpf: Sysctl hook Andrey Ignatov
2019-03-26 0:43 ` [PATCH v2 bpf-next 03/21] bpf: Introduce bpf_sysctl_get_name helper Andrey Ignatov
2019-03-26 0:43 ` [PATCH v2 bpf-next 04/21] bpf: Introduce bpf_sysctl_get_current_value helper Andrey Ignatov
2019-03-26 0:43 ` [PATCH v2 bpf-next 05/21] bpf: Introduce bpf_sysctl_{get,set}_new_value helpers Andrey Ignatov
2019-04-04 14:37 ` Daniel Borkmann
2019-04-05 0:20 ` Andrey Ignatov
2019-03-26 0:43 ` [PATCH v2 bpf-next 06/21] bpf: Add file_pos field to bpf_sysctl ctx Andrey Ignatov
2019-03-26 0:43 ` [PATCH v2 bpf-next 07/21] bpf: Sync bpf.h to tools/ Andrey Ignatov
2019-03-26 0:43 ` [PATCH v2 bpf-next 08/21] libbpf: Support sysctl hook Andrey Ignatov
2019-03-26 0:43 ` [PATCH v2 bpf-next 09/21] selftests/bpf: Test sysctl section name Andrey Ignatov
2019-03-26 0:43 ` [PATCH v2 bpf-next 10/21] selftests/bpf: Test BPF_CGROUP_SYSCTL Andrey Ignatov
2019-03-26 0:43 ` [PATCH v2 bpf-next 11/21] selftests/bpf: Test bpf_sysctl_get_name helper Andrey Ignatov
2019-03-26 0:43 ` [PATCH v2 bpf-next 12/21] selftests/bpf: Test sysctl_get_current_value helper Andrey Ignatov
2019-03-26 0:43 ` [PATCH v2 bpf-next 13/21] selftests/bpf: Test bpf_sysctl_{get,set}_new_value helpers Andrey Ignatov
2019-03-26 0:43 ` [PATCH v2 bpf-next 14/21] selftests/bpf: Test file_pos field in bpf_sysctl ctx Andrey Ignatov
2019-03-26 0:43 ` Andrey Ignatov [this message]
2019-03-26 0:43 ` [PATCH v2 bpf-next 16/21] bpf: Introduce bpf_strtol and bpf_strtoul helpers Andrey Ignatov
2019-03-26 0:43 ` [PATCH v2 bpf-next 17/21] bpf: Sync bpf.h to tools/ Andrey Ignatov
2019-03-26 0:43 ` [PATCH v2 bpf-next 18/21] selftests/bpf: Add sysctl and strtoX helpers to bpf_helpers.h Andrey Ignatov
2019-03-26 0:43 ` [PATCH v2 bpf-next 19/21] selftests/bpf: Test ARG_PTR_TO_LONG arg type Andrey Ignatov
2019-03-26 0:43 ` [PATCH v2 bpf-next 20/21] selftests/bpf: Test bpf_strtol and bpf_strtoul helpers Andrey Ignatov
2019-03-26 0:43 ` [PATCH v2 bpf-next 21/21] selftests/bpf: C based test for sysctl and strtoX Andrey Ignatov
2019-03-26 20:34 ` [PATCH v2 bpf-next 00/21] bpf: Sysctl hook Alexei Starovoitov
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