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Date:   Tue, 5 Jul 2022 14:29:04 +0300
From:   "Konstantin Meskhidze (A)" <konstantin.meskhidze@...wei.com>
To:     Mickaël Salaün <mic@...ikod.net>
CC:     <willemdebruijn.kernel@...il.com>,
        <linux-security-module@...r.kernel.org>, <netdev@...r.kernel.org>,
        <netfilter-devel@...r.kernel.org>, <yusongping@...wei.com>,
        <anton.sirazetdinov@...wei.com>
Subject: Re: [PATCH v6 01/17] landlock: renames access mask



7/1/2022 8:08 PM, Mickaël Salaün пишет:
> 
> On 21/06/2022 10:22, Konstantin Meskhidze wrote:
>> To support network type rules,
>> this modification extends and renames
>> ruleset's access masks.
>> This patch adds filesystem helper functions
>> to set and get filesystem mask. Also the
>> modification adds a helper structure
>> landlock_access_mask to support managing
>> multiple access mask.
> 
> Please use a text-width of 72 columns for all commit messages. You can
> also split them into paragraphs.
> 
   By the way, are you going to review the rest patches?
>> 
>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
>> ---
>> 
>> Changes since v5:
>> * Changes access_mask_t to u32.
>> * Formats code with clang-format-14.
>> 
>> Changes since v4:
>> * Deletes struct landlock_access_mask.
>> 
>> Changes since v3:
>> * Splits commit.
>> * Adds get_mask, set_mask helpers for filesystem.
>> * Adds new struct landlock_access_mask.
>> 
>> ---
>>   security/landlock/fs.c       |  7 ++++---
>>   security/landlock/ruleset.c  | 18 +++++++++---------
>>   security/landlock/ruleset.h  | 25 ++++++++++++++++++++-----
>>   security/landlock/syscalls.c |  7 ++++---
>>   4 files changed, 37 insertions(+), 20 deletions(-)
>> 
>> diff --git a/security/landlock/fs.c b/security/landlock/fs.c
>> index ec5a6247cd3e..e6da08ed99d1 100644
>> --- a/security/landlock/fs.c
>> +++ b/security/landlock/fs.c
>> @@ -167,7 +167,8 @@ int landlock_append_fs_rule(struct landlock_ruleset *const ruleset,
>>   		return -EINVAL;
>> 
>>   	/* Transforms relative access rights to absolute ones. */
>> -	access_rights |= LANDLOCK_MASK_ACCESS_FS & ~ruleset->fs_access_masks[0];
>> +	access_rights |= LANDLOCK_MASK_ACCESS_FS &
>> +			 ~landlock_get_fs_access_mask(ruleset, 0);
>>   	object = get_inode_object(d_backing_inode(path->dentry));
>>   	if (IS_ERR(object))
>>   		return PTR_ERR(object);
>> @@ -286,7 +287,7 @@ get_handled_accesses(const struct landlock_ruleset *const domain)
>> 
>>   		for (layer_level = 0; layer_level < domain->num_layers;
>>   		     layer_level++) {
>> -			if (domain->fs_access_masks[layer_level] &
>> +			if (landlock_get_fs_access_mask(domain, layer_level) &
>>   			    BIT_ULL(access_bit)) {
>>   				access_dom |= BIT_ULL(access_bit);
>>   				break;
>> @@ -316,7 +317,7 @@ init_layer_masks(const struct landlock_ruleset *const domain,
>> 
>>   		for_each_set_bit(access_bit, &access_req,
>>   				 ARRAY_SIZE(*layer_masks)) {
>> -			if (domain->fs_access_masks[layer_level] &
>> +			if (landlock_get_fs_access_mask(domain, layer_level) &
>>   			    BIT_ULL(access_bit)) {
>>   				(*layer_masks)[access_bit] |=
>>   					BIT_ULL(layer_level);
>> diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
>> index 996484f98bfd..a3fd58d01f09 100644
>> --- a/security/landlock/ruleset.c
>> +++ b/security/landlock/ruleset.c
>> @@ -29,7 +29,7 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers)
>>   	struct landlock_ruleset *new_ruleset;
>> 
>>   	new_ruleset =
>> -		kzalloc(struct_size(new_ruleset, fs_access_masks, num_layers),
>> +		kzalloc(struct_size(new_ruleset, access_masks, num_layers),
>>   			GFP_KERNEL_ACCOUNT);
>>   	if (!new_ruleset)
>>   		return ERR_PTR(-ENOMEM);
>> @@ -40,22 +40,22 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers)
>>   	/*
>>   	 * hierarchy = NULL
>>   	 * num_rules = 0
>> -	 * fs_access_masks[] = 0
>> +	 * access_masks[] = 0
>>   	 */
>>   	return new_ruleset;
>>   }
>> 
>>   struct landlock_ruleset *
>> -landlock_create_ruleset(const access_mask_t fs_access_mask)
>> +landlock_create_ruleset(const access_mask_t access_mask)
>>   {
>>   	struct landlock_ruleset *new_ruleset;
>> 
>>   	/* Informs about useless ruleset. */
>> -	if (!fs_access_mask)
>> +	if (!access_mask)
>>   		return ERR_PTR(-ENOMSG);
>>   	new_ruleset = create_ruleset(1);
>>   	if (!IS_ERR(new_ruleset))
>> -		new_ruleset->fs_access_masks[0] = fs_access_mask;
>> +		landlock_set_fs_access_mask(new_ruleset, access_mask, 0);
>>   	return new_ruleset;
>>   }
>> 
>> @@ -117,7 +117,7 @@ static void build_check_ruleset(void)
>>   		.num_rules = ~0,
>>   		.num_layers = ~0,
>>   	};
>> -	typeof(ruleset.fs_access_masks[0]) fs_access_mask = ~0;
>> +	typeof(ruleset.access_masks[0]) fs_access_mask = ~0;
>> 
>>   	BUILD_BUG_ON(ruleset.num_rules < LANDLOCK_MAX_NUM_RULES);
>>   	BUILD_BUG_ON(ruleset.num_layers < LANDLOCK_MAX_NUM_LAYERS);
>> @@ -281,7 +281,7 @@ static int merge_ruleset(struct landlock_ruleset *const dst,
>>   		err = -EINVAL;
>>   		goto out_unlock;
>>   	}
>> -	dst->fs_access_masks[dst->num_layers - 1] = src->fs_access_masks[0];
>> +	dst->access_masks[dst->num_layers - 1] = src->access_masks[0];
>> 
>>   	/* Merges the @src tree. */
>>   	rbtree_postorder_for_each_entry_safe(walker_rule, next_rule, &src->root,
>> @@ -340,8 +340,8 @@ static int inherit_ruleset(struct landlock_ruleset *const parent,
>>   		goto out_unlock;
>>   	}
>>   	/* Copies the parent layer stack and leaves a space for the new layer. */
>> -	memcpy(child->fs_access_masks, parent->fs_access_masks,
>> -	       flex_array_size(parent, fs_access_masks, parent->num_layers));
>> +	memcpy(child->access_masks, parent->access_masks,
>> +	       flex_array_size(parent, access_masks, parent->num_layers));
>> 
>>   	if (WARN_ON_ONCE(!parent->hierarchy)) {
>>   		err = -EINVAL;
>> diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
>> index d43231b783e4..bd7ab39859bf 100644
>> --- a/security/landlock/ruleset.h
>> +++ b/security/landlock/ruleset.h
>> @@ -19,7 +19,7 @@
>>   #include "limits.h"
>>   #include "object.h"
>> 
>> -typedef u16 access_mask_t;
>> +typedef u32 access_mask_t;
>>   /* Makes sure all filesystem access rights can be stored. */
>>   static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_FS);
>>   /* Makes sure for_each_set_bit() and for_each_clear_bit() calls are OK. */
>> @@ -110,7 +110,7 @@ struct landlock_ruleset {
>>   		 * section.  This is only used by
>>   		 * landlock_put_ruleset_deferred() when @usage reaches zero.
>>   		 * The fields @lock, @usage, @num_rules, @num_layers and
>> -		 * @fs_access_masks are then unused.
>> +		 * @access_masks are then unused.
>>   		 */
>>   		struct work_struct work_free;
>>   		struct {
>> @@ -137,7 +137,7 @@ struct landlock_ruleset {
>>   			 */
>>   			u32 num_layers;
>>   			/**
>> -			 * @fs_access_masks: Contains the subset of filesystem
>> +			 * @access_masks: Contains the subset of filesystem
>>   			 * actions that are restricted by a ruleset.  A domain
>>   			 * saves all layers of merged rulesets in a stack
>>   			 * (FAM), starting from the first layer to the last
>> @@ -148,13 +148,13 @@ struct landlock_ruleset {
>>   			 * layers are set once and never changed for the
>>   			 * lifetime of the ruleset.
>>   			 */
>> -			access_mask_t fs_access_masks[];
>> +			access_mask_t access_masks[];
>>   		};
>>   	};
>>   };
>> 
>>   struct landlock_ruleset *
>> -landlock_create_ruleset(const access_mask_t fs_access_mask);
>> +landlock_create_ruleset(const access_mask_t access_mask);
>> 
>>   void landlock_put_ruleset(struct landlock_ruleset *const ruleset);
>>   void landlock_put_ruleset_deferred(struct landlock_ruleset *const ruleset);
>> @@ -177,4 +177,19 @@ static inline void landlock_get_ruleset(struct landlock_ruleset *const ruleset)
>>   		refcount_inc(&ruleset->usage);
>>   }
>> 
>> +/* A helper function to set a filesystem mask. */
>> +static inline void
>> +landlock_set_fs_access_mask(struct landlock_ruleset *ruleset,
>> +			    const access_mask_t access_maskset, u16 mask_level)
>> +{
>> +	ruleset->access_masks[mask_level] = access_maskset;
>> +}
>> +
>> +/* A helper function to get a filesystem mask. */
>> +static inline u32
> 
> You need to use access_mask_t everywhere, including here.
> 
>> +landlock_get_fs_access_mask(const struct landlock_ruleset *ruleset,
>> +			    u16 mask_level)
>> +{
>> +	return ruleset->access_masks[mask_level];
>> +}
>>   #endif /* _SECURITY_LANDLOCK_RULESET_H */
>> diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
>> index 735a0865ea11..5836736ce9d7 100644
>> --- a/security/landlock/syscalls.c
>> +++ b/security/landlock/syscalls.c
>> @@ -346,10 +346,11 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
>>   	}
>>   	/*
>>   	 * Checks that allowed_access matches the @ruleset constraints
>> -	 * (ruleset->fs_access_masks[0] is automatically upgraded to 64-bits).
>> +	 * (ruleset->access_masks[0] is automatically upgraded to 64-bits).
>>   	 */
>> -	if ((path_beneath_attr.allowed_access | ruleset->fs_access_masks[0]) !=
>> -	    ruleset->fs_access_masks[0]) {
>> +	if ((path_beneath_attr.allowed_access |
>> +	     landlock_get_fs_access_mask(ruleset, 0)) !=
>> +	    landlock_get_fs_access_mask(ruleset, 0)) {
>>   		err = -EINVAL;
>>   		goto out_put_ruleset;
>>   	}
>> --
>> 2.25.1
>> 
> .

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