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From: Daniel Borkmann <daniel@iogearbox.net>
To: Hangbin Liu <liuhangbin@gmail.com>, bpf@vger.kernel.org
Cc: netdev@vger.kernel.org,
	"Toke Høiland-Jørgensen" <toke@redhat.com>,
	"Jiri Benc" <jbenc@redhat.com>,
	"Jesper Dangaard Brouer" <brouer@redhat.com>,
	"Eelco Chaudron" <echaudro@redhat.com>,
	ast@kernel.org, "Lorenzo Bianconi" <lorenzo.bianconi@redhat.com>,
	"David Ahern" <dsahern@gmail.com>,
	"Andrii Nakryiko B" <andrii.nakryiko@gmail.com>
Subject: Re: [PATCHv9 bpf-next 1/5] bpf: add a new bpf argument type ARG_CONST_MAP_PTR_OR_NULL
Date: Fri, 28 Aug 2020 23:56:37 +0200
Message-ID: <a6ef587d-8128-a926-16b3-01e7ef7b4c8b@iogearbox.net> (raw)
In-Reply-To: <20200826132002.2808380-2-liuhangbin@gmail.com>

On 8/26/20 3:19 PM, Hangbin Liu wrote:
> Add a new bpf argument type ARG_CONST_MAP_PTR_OR_NULL which could be
> used when we want to allow NULL pointer for map parameter. The bpf helper
> need to take care and check if the map is NULL when use this type.
> 
> Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
> ---
> 
> v9: merge the patch from [1] in to this series.
> v1-v8: no this patch
> 
> [1] https://lore.kernel.org/bpf/20200715070001.2048207-1-liuhangbin@gmail.com/
> ---
>   include/linux/bpf.h   |  2 ++
>   kernel/bpf/verifier.c | 23 ++++++++++++++++-------
>   2 files changed, 18 insertions(+), 7 deletions(-)
> 
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index a6131d95e31e..cb40a1281ea2 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -276,6 +276,7 @@ enum bpf_arg_type {
>   	ARG_PTR_TO_ALLOC_MEM,	/* pointer to dynamically allocated memory */
>   	ARG_PTR_TO_ALLOC_MEM_OR_NULL,	/* pointer to dynamically allocated memory or NULL */
>   	ARG_CONST_ALLOC_SIZE_OR_ZERO,	/* number of allocated bytes requested */
> +	ARG_CONST_MAP_PTR_OR_NULL,	/* const argument used as pointer to bpf_map or NULL */
>   };
>   
>   /* type of values returned from helper functions */
> @@ -369,6 +370,7 @@ enum bpf_reg_type {
>   	PTR_TO_RDONLY_BUF_OR_NULL, /* reg points to a readonly buffer or NULL */
>   	PTR_TO_RDWR_BUF,	 /* reg points to a read/write buffer */
>   	PTR_TO_RDWR_BUF_OR_NULL, /* reg points to a read/write buffer or NULL */
> +	CONST_PTR_TO_MAP_OR_NULL, /* reg points to struct bpf_map or NULL */

Why is this needed & where do you assign it? Also, if we were to use CONST_PTR_TO_MAP_OR_NULL
then it's missing few things like rejection of arithmetic in adjust_ptr_min_max_vals(), handling
in pruning logic etc.

Either way, given no helper currently returns CONST_PTR_TO_MAP_OR_NULL, the ARG_CONST_MAP_PTR_OR_NULL
one should be sufficient, so I'd suggest to remove the CONST_PTR_TO_MAP_OR_NULL bits.

>   };
>   
>   /* The information passed from prog-specific *_is_valid_access
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 7e5908b83ec7..53a84335a8fd 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -411,7 +411,8 @@ static bool reg_type_may_be_null(enum bpf_reg_type type)
>   	       type == PTR_TO_BTF_ID_OR_NULL ||
>   	       type == PTR_TO_MEM_OR_NULL ||
>   	       type == PTR_TO_RDONLY_BUF_OR_NULL ||
> -	       type == PTR_TO_RDWR_BUF_OR_NULL;
> +	       type == PTR_TO_RDWR_BUF_OR_NULL ||
> +	       type == CONST_PTR_TO_MAP_OR_NULL;
>   }
>   
>   static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg)
> @@ -427,7 +428,8 @@ static bool reg_type_may_be_refcounted_or_null(enum bpf_reg_type type)
>   		type == PTR_TO_TCP_SOCK ||
>   		type == PTR_TO_TCP_SOCK_OR_NULL ||
>   		type == PTR_TO_MEM ||
> -		type == PTR_TO_MEM_OR_NULL;
> +		type == PTR_TO_MEM_OR_NULL ||
> +		type == CONST_PTR_TO_MAP_OR_NULL;
>   }
>   
>   static bool arg_type_may_be_refcounted(enum bpf_arg_type type)
> @@ -509,6 +511,7 @@ static const char * const reg_type_str[] = {
>   	[PTR_TO_RDONLY_BUF_OR_NULL] = "rdonly_buf_or_null",
>   	[PTR_TO_RDWR_BUF]	= "rdwr_buf",
>   	[PTR_TO_RDWR_BUF_OR_NULL] = "rdwr_buf_or_null",
> +	[CONST_PTR_TO_MAP_OR_NULL] = "map_ptr_or_null",
>   };
>   
>   static char slot_type_char[] = {
> @@ -3957,9 +3960,13 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
>   		expected_type = SCALAR_VALUE;
>   		if (type != expected_type)
>   			goto err_type;
> -	} else if (arg_type == ARG_CONST_MAP_PTR) {
> +	} else if (arg_type == ARG_CONST_MAP_PTR ||
> +		   arg_type == ARG_CONST_MAP_PTR_OR_NULL) {
>   		expected_type = CONST_PTR_TO_MAP;
> -		if (type != expected_type)
> +		if (register_is_null(reg) &&
> +		    arg_type == ARG_CONST_MAP_PTR_OR_NULL)
> +			/* final test in check_stack_boundary() */;

Where is that test in the code? Copy-paste leftover comment?

> +		else if (type != expected_type)
>   			goto err_type;
>   	} else if (arg_type == ARG_PTR_TO_CTX ||
>   		   arg_type == ARG_PTR_TO_CTX_OR_NULL) {
> @@ -4076,9 +4083,9 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
>   		return -EFAULT;
>   	}
>   
> -	if (arg_type == ARG_CONST_MAP_PTR) {
> -		/* bpf_map_xxx(map_ptr) call: remember that map_ptr */
> -		meta->map_ptr = reg->map_ptr;
> +	if (arg_type == ARG_CONST_MAP_PTR ||
> +	    arg_type == ARG_CONST_MAP_PTR_OR_NULL) {
> +		meta->map_ptr = register_is_null(reg) ? NULL : reg->map_ptr;
>   	} else if (arg_type == ARG_PTR_TO_MAP_KEY) {
>   		/* bpf_map_xxx(..., map_ptr, ..., key) call:
>   		 * check that [key, key + map->key_size) are within
> @@ -6977,6 +6984,8 @@ static void mark_ptr_or_null_reg(struct bpf_func_state *state,
>   			reg->type = PTR_TO_RDONLY_BUF;
>   		} else if (reg->type == PTR_TO_RDWR_BUF_OR_NULL) {
>   			reg->type = PTR_TO_RDWR_BUF;
> +		} else if (reg->type == CONST_PTR_TO_MAP_OR_NULL) {
> +			reg->type = CONST_PTR_TO_MAP;
>   		}
>   		if (is_null) {
>   			/* We don't need id and ref_obj_id from this point
> 


  reply index

Thread overview: 127+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-15  8:54 [RFC PATCH bpf-next 0/2] xdp: add dev map multicast support Hangbin Liu
2020-04-15  8:54 ` [RFC PATCH bpf-next 1/2] " Hangbin Liu
2020-04-20  9:52   ` Hangbin Liu
2020-04-15  8:54 ` [RFC PATCH bpf-next 2/2] sample/bpf: add xdp_redirect_map_multicast test Hangbin Liu
2020-04-24  8:56 ` [RFC PATCHv2 bpf-next 0/2] xdp: add dev map multicast support Hangbin Liu
2020-04-24  8:56   ` [RFC PATCHv2 bpf-next 1/2] xdp: add a new helper for " Hangbin Liu
2020-04-24 14:19     ` Lorenzo Bianconi
2020-04-28 11:09       ` Eelco Chaudron
2020-05-06  9:35       ` Hangbin Liu
2020-04-24 14:34     ` Toke Høiland-Jørgensen
2020-05-06  9:14       ` Hangbin Liu
2020-05-06 10:00         ` Toke Høiland-Jørgensen
2020-05-08  8:53           ` Hangbin Liu
2020-05-08 14:58             ` Toke Høiland-Jørgensen
2020-05-18  8:45       ` Hangbin Liu
2020-05-19 10:15         ` Jesper Dangaard Brouer
2020-05-20  1:24           ` Hangbin Liu
2020-04-24  8:56   ` [RFC PATCHv2 bpf-next 2/2] sample/bpf: add xdp_redirect_map_multicast test Hangbin Liu
2020-04-24 14:21     ` Lorenzo Bianconi
2020-05-23  6:05 ` [PATCHv3 bpf-next 0/2] xdp: add dev map multicast support Hangbin Liu
2020-05-23  6:05   ` [PATCHv3 bpf-next 1/2] xdp: add a new helper for " Hangbin Liu
2020-05-26  7:34     ` kbuild test robot
2020-05-23  6:05   ` [PATCHv3 bpf-next 2/2] sample/bpf: add xdp_redirect_map_multicast test Hangbin Liu
2020-05-26 14:05 ` [PATCHv4 bpf-next 0/2] xdp: add dev map multicast support Hangbin Liu
2020-05-26 14:05   ` [PATCHv4 bpf-next 1/2] xdp: add a new helper for " Hangbin Liu
2020-05-27 10:29     ` Toke Høiland-Jørgensen
2020-06-10 10:18     ` Jesper Dangaard Brouer
2020-06-12  8:54       ` Hangbin Liu
2020-06-16  8:55         ` Jesper Dangaard Brouer
2020-06-16 10:11           ` Hangbin Liu
2020-06-16 14:38             ` Jesper Dangaard Brouer
2020-06-10 10:21     ` Jesper Dangaard Brouer
2020-06-10 10:29       ` Toke Høiland-Jørgensen
2020-06-16  9:04         ` Jesper Dangaard Brouer
2020-05-26 14:05   ` [PATCHv4 bpf-next 2/2] sample/bpf: add xdp_redirect_map_multicast test Hangbin Liu
2020-05-27 10:21   ` [PATCHv4 bpf-next 0/2] xdp: add dev map multicast support Toke Høiland-Jørgensen
2020-05-27 10:32     ` Eelco Chaudron
2020-05-27 12:38     ` Hangbin Liu
2020-05-27 15:04       ` Toke Høiland-Jørgensen
2020-06-16  9:09         ` Jesper Dangaard Brouer
2020-06-16  9:47           ` Hangbin Liu
2020-06-03  2:40     ` Hangbin Liu
2020-06-03 11:05       ` Toke Høiland-Jørgensen
2020-06-04  4:09         ` Hangbin Liu
2020-06-04  9:44           ` Toke Høiland-Jørgensen
2020-06-04 12:12             ` Hangbin Liu
2020-06-04 12:37               ` Toke Høiland-Jørgensen
2020-06-04 14:41                 ` Hangbin Liu
2020-06-04 16:02                   ` Toke Høiland-Jørgensen
2020-06-05  6:26                     ` Hangbin Liu
2020-06-08 15:32                       ` Toke Høiland-Jørgensen
2020-06-09  3:03                         ` Hangbin Liu
2020-06-09 20:31                           ` Toke Høiland-Jørgensen
2020-06-10  2:35                             ` Hangbin Liu
2020-06-10 10:03                               ` Jesper Dangaard Brouer
2020-07-01  4:19   ` [PATCHv5 bpf-next 0/3] xdp: add a new helper for " Hangbin Liu
2020-07-01  4:19     ` [PATCHv5 bpf-next 1/3] " Hangbin Liu
2020-07-01  5:09       ` Andrii Nakryiko
2020-07-01  6:51         ` Hangbin Liu
2020-07-01 18:33       ` kernel test robot
2020-07-01  4:19     ` [PATCHv5 bpf-next 2/3] sample/bpf: add xdp_redirect_map_multicast test Hangbin Liu
2020-07-01  4:19     ` [PATCHv5 bpf-next 3/3] selftests/bpf: add xdp_redirect_multi test Hangbin Liu
2020-07-09  1:30     ` [PATCHv6 bpf-next 0/3] xdp: add a new helper for dev map multicast support Hangbin Liu
2020-07-09  1:30       ` [PATCHv6 bpf-next 1/3] " Hangbin Liu
2020-07-09 16:33         ` David Ahern
2020-07-10  6:55           ` Hangbin Liu
2020-07-10 13:46             ` David Ahern
2020-07-11  0:26               ` Hangbin Liu
2020-07-11 16:09                 ` David Ahern
2020-07-09  1:30       ` [PATCHv6 bpf-next 2/3] sample/bpf: add xdp_redirect_map_multicast test Hangbin Liu
2020-07-09 22:40         ` Daniel Borkmann
2020-07-10  6:41           ` Hangbin Liu
2020-07-10 14:32             ` Daniel Borkmann
2020-07-11  0:21               ` Hangbin Liu
2020-07-09  1:30       ` [PATCHv6 bpf-next 3/3] selftests/bpf: add xdp_redirect_multi test Hangbin Liu
2020-07-09 22:37       ` [PATCHv6 bpf-next 0/3] xdp: add a new helper for dev map multicast support Daniel Borkmann
2020-07-10  7:36         ` Hangbin Liu
2020-07-10 15:02           ` Daniel Borkmann
2020-07-10 16:52             ` David Ahern
2020-07-14  6:32       ` [PATCHv7 " Hangbin Liu
2020-07-14  6:32         ` [PATCHv7 bpf-next 1/3] " Hangbin Liu
2020-07-14 21:52           ` Toke Høiland-Jørgensen
2020-07-15 12:25             ` Hangbin Liu
2020-07-14  6:32         ` [PATCHv7 bpf-next 2/3] sample/bpf: add xdp_redirect_map_multicast test Hangbin Liu
2020-07-14  6:32         ` [PATCHv7 bpf-next 3/3] selftests/bpf: add xdp_redirect_multi test Hangbin Liu
2020-07-14 12:29         ` [PATCHv7 bpf-next 0/3] xdp: add a new helper for dev map multicast support Toke Høiland-Jørgensen
2020-07-14 17:12           ` David Ahern
2020-07-14 21:53             ` Toke Høiland-Jørgensen
2020-07-15 12:31               ` Hangbin Liu
2020-07-15  3:45             ` Hangbin Liu
2020-07-15 13:08         ` [PATCHv8 " Hangbin Liu
2020-07-15 13:08           ` [PATCHv8 bpf-next 1/3] " Hangbin Liu
2020-07-15 13:08           ` [PATCHv8 bpf-next 2/3] sample/bpf: add xdp_redirect_map_multicast test Hangbin Liu
2020-07-15 13:08           ` [PATCHv8 bpf-next 3/3] selftests/bpf: add xdp_redirect_multi test Hangbin Liu
2020-08-26 13:19           ` [PATCHv9 bpf-next 0/5] xdp: add a new helper for dev map multicast support Hangbin Liu
2020-08-26 13:19             ` [PATCHv9 bpf-next 1/5] bpf: add a new bpf argument type ARG_CONST_MAP_PTR_OR_NULL Hangbin Liu
2020-08-28 21:56               ` Daniel Borkmann [this message]
2020-09-03  9:15                 ` Hangbin Liu
2020-08-26 13:19             ` [PATCHv9 bpf-next 2/5] xdp: add a new helper for dev map multicast support Hangbin Liu
2020-08-28 22:05               ` Daniel Borkmann
2020-08-26 13:20             ` [PATCHv9 bpf-next 3/5] sample/bpf: add xdp_redirect_map_multicast test Hangbin Liu
2020-08-26 13:20             ` [PATCHv9 bpf-next 4/5] selftests/bpf: add xdp_redirect_multi test Hangbin Liu
2020-08-26 13:20             ` [PATCHv9 bpf-next 5/5] selftests/bpf: Add verifier tests for bpf arg ARG_CONST_MAP_PTR_OR_NULL Hangbin Liu
2020-09-03 10:26             ` [PATCHv10 bpf-next 0/5] xdp: add a new helper for dev map multicast support Hangbin Liu
2020-09-03 10:26               ` [PATCHv10 bpf-next 1/5] bpf: add a new bpf argument type ARG_CONST_MAP_PTR_OR_NULL Hangbin Liu
2020-09-04 14:26                 ` Daniel Borkmann
2020-09-03 10:26               ` [PATCHv10 bpf-next 2/5] xdp: add a new helper for dev map multicast support Hangbin Liu
2020-09-04 14:22                 ` Daniel Borkmann
2020-09-03 10:26               ` [PATCHv10 bpf-next 3/5] sample/bpf: add xdp_redirect_map_multicast test Hangbin Liu
2020-09-03 10:27               ` [PATCHv10 bpf-next 4/5] selftests/bpf: add xdp_redirect_multi test Hangbin Liu
2020-09-03 10:27               ` [PATCHv10 bpf-next 5/5] selftests/bpf: Add verifier tests for bpf arg ARG_CONST_MAP_PTR_OR_NULL Hangbin Liu
2020-09-07  8:27               ` [PATCHv11 bpf-next 0/5] xdp: add a new helper for dev map multicast support Hangbin Liu
2020-09-07  8:27                 ` [PATCHv11 bpf-next 1/5] bpf: add a new bpf argument type ARG_CONST_MAP_PTR_OR_NULL Hangbin Liu
2020-09-07  8:27                 ` [PATCHv11 bpf-next 2/5] xdp: add a new helper for dev map multicast support Hangbin Liu
2020-09-09 21:52                   ` Alexei Starovoitov
2020-09-10  2:35                     ` Hangbin Liu
2020-09-10  3:30                       ` David Ahern
2020-09-10  5:35                         ` Alexei Starovoitov
2020-09-10  9:44                           ` Toke Høiland-Jørgensen
2020-09-10 15:39                             ` Alexei Starovoitov
2020-09-10 17:50                             ` Jesper Dangaard Brouer
2020-09-10 18:35                               ` David Ahern
2020-09-11  7:58                                 ` Jesper Dangaard Brouer
2020-09-15 16:12                                   ` David Ahern
2020-09-07  8:27                 ` [PATCHv11 bpf-next 3/5] sample/bpf: add xdp_redirect_map_multicast test Hangbin Liu
2020-09-07  8:27                 ` [PATCHv11 bpf-next 4/5] selftests/bpf: add xdp_redirect_multi test Hangbin Liu
2020-09-07  8:27                 ` [PATCHv11 bpf-next 5/5] selftests/bpf: Add verifier tests for bpf arg ARG_CONST_MAP_PTR_OR_NULL Hangbin Liu

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