Re: [PATCH v8 01/12] landlock: Make ruleset's access masks more generic

[Mickaël Salaün <mic@xxxxxxxxxxx>]

On 28/11/2022 03:53, Konstantin Meskhidze (A) wrote:
> 11/17/2022 9:41 PM, Mickaël Salaün пишет:
> > On 21/10/2022 17:26, Konstantin Meskhidze wrote:
> > > To support network type rules, this modification renames ruleset's
> > > access masks and modifies it's type to access_masks_t. This patch
> > > adds filesystem helper functions to add and get filesystem mask.
> > >
> > > Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@xxxxxxxxxx>
> > > ---
> > >
> > > Changes since v7:
> > > * Refactors commit message.
> > >
> > > Changes since v6:
> > > * Adds a new access_masks_t for struct ruleset.
> > > * Renames landlock_set_fs_access_mask() to landlock_add_fs_access_mask()
> > >     because it OR values.
> > > * Makes landlock_add_fs_access_mask() more resilient incorrect values.
> > > * Refactors landlock_get_fs_access_mask().
> > >
> > > Changes since v6:
> > > * Adds a new access_masks_t for struct ruleset.
> > > * Renames landlock_set_fs_access_mask() to landlock_add_fs_access_mask()
> > >     because it OR values.
> > > * Makes landlock_add_fs_access_mask() more resilient incorrect values.
> > > * Refactors landlock_get_fs_access_mask().
> > >
> > > 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       | 10 +++++-----
> > >    security/landlock/limits.h   |  1 +
> > >    security/landlock/ruleset.c  | 17 +++++++++--------
> > >    security/landlock/ruleset.h  | 35 +++++++++++++++++++++++++++++++----
> > >    security/landlock/syscalls.c |  7 ++++---
> > >    5 files changed, 50 insertions(+), 20 deletions(-)
> > >
> > > diff --git a/security/landlock/fs.c b/security/landlock/fs.c
> > > index adcea0fe7e68..0d57c6479d29 100644
> > > --- a/security/landlock/fs.c
> > > +++ b/security/landlock/fs.c
> > > @@ -178,9 +178,9 @@ 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_INITIALLY_DENIED);
> > > +	access_rights |= LANDLOCK_MASK_ACCESS_FS &
> > > +			 ~(landlock_get_fs_access_mask(ruleset, 0) |
> > > +			   ACCESS_INITIALLY_DENIED);
> > >    	object = get_inode_object(d_backing_inode(path->dentry));
> > >    	if (IS_ERR(object))
> > >    		return PTR_ERR(object);
> > > @@ -294,7 +294,7 @@ get_handled_accesses(const struct landlock_ruleset *const domain)
> > >    	size_t layer_level;
> > >
> > >    	for (layer_level = 0; layer_level < domain->num_layers; layer_level++)
> > > -		access_dom |= domain->fs_access_masks[layer_level];
> > > +		access_dom |= landlock_get_fs_access_mask(domain, layer_level);
> > >    	return access_dom & LANDLOCK_MASK_ACCESS_FS;
> >
> > You can remove `& LANDLOCK_MASK_ACCESS_FS` here because it is now part
> > of landlock_get_fs_access_mask().
>
>     Ok. I got it. Thanks.
> > >    }
> > >
> > > @@ -336,7 +336,7 @@ init_layer_masks(const struct landlock_ruleset *const domain,
> > >    			 * access rights.
> > >    			 */
> > >    			if (BIT_ULL(access_bit) &
> > > -			    (domain->fs_access_masks[layer_level] |
> > > +			    (landlock_get_fs_access_mask(domain, layer_level) |
> > >    			     ACCESS_INITIALLY_DENIED)) {
> > >    				(*layer_masks)[access_bit] |=
> > >    					BIT_ULL(layer_level);
> > > diff --git a/security/landlock/limits.h b/security/landlock/limits.h
> > > index 82288f0e9e5e..bafb3b8dc677 100644
> > > --- a/security/landlock/limits.h
> > > +++ b/security/landlock/limits.h
> > > @@ -21,6 +21,7 @@
> > >    #define LANDLOCK_LAST_ACCESS_FS		LANDLOCK_ACCESS_FS_TRUNCATE
> > >    #define LANDLOCK_MASK_ACCESS_FS		((LANDLOCK_LAST_ACCESS_FS << 1) - 1)
> > >    #define LANDLOCK_NUM_ACCESS_FS		__const_hweight64(LANDLOCK_MASK_ACCESS_FS)
> > > +#define LANDLOCK_SHIFT_ACCESS_FS	0
> > >
> > >    /* clang-format on */
> > >
> > > diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
> > > index 996484f98bfd..1f3188b4e313 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);
> > > @@ -40,7 +40,7 @@ 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;
> > >    }
> > > @@ -55,7 +55,7 @@ landlock_create_ruleset(const access_mask_t fs_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_add_fs_access_mask(new_ruleset, fs_access_mask, 0);
> > >    	return new_ruleset;
> > >    }
> > >
> > > @@ -117,11 +117,12 @@ 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]) access_masks = ~0;
> > >
> > >    	BUILD_BUG_ON(ruleset.num_rules < LANDLOCK_MAX_NUM_RULES);
> > >    	BUILD_BUG_ON(ruleset.num_layers < LANDLOCK_MAX_NUM_LAYERS);
> > > -	BUILD_BUG_ON(fs_access_mask < LANDLOCK_MASK_ACCESS_FS);
> > > +	BUILD_BUG_ON(access_masks <
> > > +		     (LANDLOCK_MASK_ACCESS_FS << LANDLOCK_SHIFT_ACCESS_FS));
> > >    }
> > >
> > >    /**
> > > @@ -281,7 +282,7 @@ 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 +341,8 @@ 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..f2ad932d396c 100644
> > > --- a/security/landlock/ruleset.h
> > > +++ b/security/landlock/ruleset.h
> > > @@ -25,6 +25,11 @@ 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. */
> > >    static_assert(sizeof(unsigned long) >= sizeof(access_mask_t));
> > >
> > > +/* Ruleset access masks. */
> > > +typedef u16 access_masks_t;
> > > +/* Makes sure all ruleset access rights can be stored. */
> > > +static_assert(BITS_PER_TYPE(access_masks_t) >= LANDLOCK_NUM_ACCESS_FS);
> > > +
> > >    typedef u16 layer_mask_t;
> > >    /* Makes sure all layers can be checked. */
> > >    static_assert(BITS_PER_TYPE(layer_mask_t) >= LANDLOCK_MAX_NUM_LAYERS);
> > > @@ -110,7 +115,7 @@ 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 +142,7 @@ 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 +153,13 @@ struct landlock_ruleset {
> > >    			 * layers are set once and never changed for the
> > >    			 * lifetime of the ruleset.
> > >    			 */
> > > -			access_mask_t fs_access_masks[];
> > > +			access_masks_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 +182,26 @@ static inline void landlock_get_ruleset(struct landlock_ruleset *const ruleset)
> > >    		refcount_inc(&ruleset->usage);
> > >    }
> > >
> > > +static inline void
> > > +landlock_add_fs_access_mask(struct landlock_ruleset *const ruleset,
> > > +			    const access_mask_t fs_access_mask,
> > > +			    const u16 layer_level)
> > > +{
> > > +	access_mask_t fs_mask = fs_access_mask & LANDLOCK_MASK_ACCESS_FS;
> > > +
> > > +	/* Should already be checked in sys_landlock_create_ruleset(). */
> > > +	WARN_ON_ONCE(fs_access_mask != fs_mask);
> > > +	// TODO: Add tests to check "|=" and not "="
> >
> > This todo should be done and removed. No more todos must remain.
>     I delete it in 10/12 Patch when add network seltests.

You can delete it in this patch then. I'm reviewing the tests.