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Message-ID: <06f9ca1f-6e92-9d71-4097-e43b2f77b937@digikod.net>
Date: Fri, 8 Apr 2022 18:30:09 +0200
From: Mickaël Salaün <mic@...ikod.net>
To: Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
Cc: willemdebruijn.kernel@...il.com,
linux-security-module@...r.kernel.org, netdev@...r.kernel.org,
netfilter-devel@...r.kernel.org, yusongping@...wei.com,
artem.kuzin@...wei.com, anton.sirazetdinov@...wei.com
Subject: Re: [RFC PATCH v4 08/15] landlock: add support network rules
On 09/03/2022 14:44, Konstantin Meskhidze wrote:
> This modification adds network rules support
> in internal landlock functions (presented in ruleset.c)
> and landlock_create_ruleset syscall.
>
> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
> ---
>
> Changes since v3:
> * Split commit.
> * Add network rule support for internal landlock functions.
> * Add set_masks and get_masks for network.
> * Add rb_root root_net_port.
>
> ---
> security/landlock/fs.c | 2 +-
> security/landlock/limits.h | 6 +++
> security/landlock/ruleset.c | 88 +++++++++++++++++++++++++++++++++---
> security/landlock/ruleset.h | 14 +++++-
> security/landlock/syscalls.c | 10 +++-
> 5 files changed, 109 insertions(+), 11 deletions(-)
>
> diff --git a/security/landlock/fs.c b/security/landlock/fs.c
> index 75ebdce5cd16..5cd339061cdb 100644
> --- a/security/landlock/fs.c
> +++ b/security/landlock/fs.c
> @@ -231,7 +231,7 @@ static int check_access_path(const struct landlock_ruleset *const domain,
>
> inode = d_backing_inode(walker_path.dentry);
> object_ptr = landlock_inode(inode)->object;
> - layer_mask = landlock_unmask_layers(domain, object_ptr,
> + layer_mask = landlock_unmask_layers(domain, object_ptr, 0,
> access_request, layer_mask,
> LANDLOCK_RULE_PATH_BENEATH);
> if (layer_mask == 0) {
> diff --git a/security/landlock/limits.h b/security/landlock/limits.h
> index 2a0a1095ee27..fdbef85e4de0 100644
> --- a/security/landlock/limits.h
> +++ b/security/landlock/limits.h
> @@ -18,4 +18,10 @@
> #define LANDLOCK_LAST_ACCESS_FS LANDLOCK_ACCESS_FS_MAKE_SYM
> #define LANDLOCK_MASK_ACCESS_FS ((LANDLOCK_LAST_ACCESS_FS << 1) - 1)
>
> +#define LANDLOCK_LAST_ACCESS_NET LANDLOCK_ACCESS_NET_CONNECT_TCP
> +#define LANDLOCK_MASK_ACCESS_NET ((LANDLOCK_LAST_ACCESS_NET << 1) - 1)
> +#define LANDLOCK_MASK_SHIFT_NET 16
> +
> +#define LANDLOCK_RULE_TYPE_NUM LANDLOCK_RULE_NET_SERVICE
> +
> #endif /* _SECURITY_LANDLOCK_LIMITS_H */
> diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
> index 7179b10f3538..1cecca59a942 100644
> --- a/security/landlock/ruleset.c
> +++ b/security/landlock/ruleset.c
> @@ -35,6 +35,7 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers)
> refcount_set(&new_ruleset->usage, 1);
> mutex_init(&new_ruleset->lock);
> new_ruleset->root_inode = RB_ROOT;
> + new_ruleset->root_net_port = RB_ROOT;
> new_ruleset->num_layers = num_layers;
> /*
> * hierarchy = NULL
> @@ -58,16 +59,32 @@ u32 landlock_get_fs_access_mask(const struct landlock_ruleset *ruleset, u16 mask
> return ruleset->access_masks[mask_level];
> }
>
> +/* A helper function to set a network mask */
> +void landlock_set_net_access_mask(struct landlock_ruleset *ruleset,
> + const struct landlock_access_mask *access_mask_set,
> + u16 mask_level)
> +{
> + ruleset->access_masks[mask_level] |= (access_mask_set->net << LANDLOCK_MASK_SHIFT_NET);
> +}
> +
> +/* A helper function to get a network mask */
> +u32 landlock_get_net_access_mask(const struct landlock_ruleset *ruleset, u16 mask_level)
> +{
> + return (ruleset->access_masks[mask_level] >> LANDLOCK_MASK_SHIFT_NET);
> +}
Both these helpers should be "static inline" and moved in net.h
> +
> struct landlock_ruleset *landlock_create_ruleset(const struct landlock_access_mask *access_mask_set)
> {
> struct landlock_ruleset *new_ruleset;
>
> /* Informs about useless ruleset. */
> - if (!access_mask_set->fs)
> + if (!access_mask_set->fs && !access_mask_set->net)
> return ERR_PTR(-ENOMSG);
> new_ruleset = create_ruleset(1);
> - if (!IS_ERR(new_ruleset))
This is better:
if (IS_ERR(new_ruleset))
return new_ruleset;
if (access_mask_set->fs)
...
> + if (!IS_ERR(new_ruleset) && access_mask_set->fs)
> landlock_set_fs_access_mask(new_ruleset, access_mask_set, 0);
> + if (!IS_ERR(new_ruleset) && access_mask_set->net)
> + landlock_set_net_access_mask(new_ruleset, access_mask_set, 0);
> return new_ruleset;
> }
>
> @@ -111,6 +128,9 @@ static struct landlock_rule *create_rule(
> landlock_get_object(object_ptr);
> new_rule->object.ptr = object_ptr;
> break;
> + case LANDLOCK_RULE_NET_SERVICE:
> + new_rule->object.data = object_data;
> + break;
> default:
> return ERR_PTR(-EINVAL);
> }
> @@ -145,10 +165,12 @@ static void build_check_ruleset(void)
> .num_layers = ~0,
> };
> typeof(ruleset.access_masks[0]) fs_access_mask = ~0;
> + typeof(ruleset.access_masks[0]) net_access_mask = ~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(net_access_mask < LANDLOCK_MASK_ACCESS_NET);
> }
>
> /**
> @@ -191,6 +213,12 @@ static int insert_rule(struct landlock_ruleset *const ruleset,
Already reviewed.
[...]
> @@ -319,6 +363,9 @@ static int tree_merge(struct landlock_ruleset *const src,
> case LANDLOCK_RULE_PATH_BENEATH:
> src_root = &src->root_inode;
> break;
> + case LANDLOCK_RULE_NET_SERVICE:
> + src_root = &src->root_net_port;
> + break;
> default:
> return -EINVAL;
> }
> @@ -338,11 +385,14 @@ static int tree_merge(struct landlock_ruleset *const src,
> return err;
> }
> layers[0].access = walker_rule->layers[0].access;
> -
nit: Please keep this empty line.
> switch (rule_type) {
> case LANDLOCK_RULE_PATH_BENEATH:
> err = insert_rule(dst, walker_rule->object.ptr, 0, &layers,
> - ARRAY_SIZE(layers), rule_type);
> + ARRAY_SIZE(layers), rule_type);
Please don't insert this kind of formatting in unrelated patches.
> + break;
> + case LANDLOCK_RULE_NET_SERVICE:
> + err = insert_rule(dst, NULL, walker_rule->object.data, &layers,
> + ARRAY_SIZE(layers), rule_type);
> break;
> }
> if (err)
> @@ -379,6 +429,10 @@ static int merge_ruleset(struct landlock_ruleset *const dst,
> err = tree_merge(src, dst, LANDLOCK_RULE_PATH_BENEATH);
> if (err)
> goto out_unlock;
> + /* Merges the @src network tree. */
> + err = tree_merge(src, dst, LANDLOCK_RULE_NET_SERVICE);
> + if (err)
> + goto out_unlock;
>
> out_unlock:
> mutex_unlock(&src->lock);
> @@ -398,6 +452,9 @@ static int tree_copy(struct landlock_ruleset *const parent,
> case LANDLOCK_RULE_PATH_BENEATH:
> parent_root = &parent->root_inode;
> break;
> + case LANDLOCK_RULE_NET_SERVICE:
> + parent_root = &parent->root_net_port;
> + break;
> default:
> return -EINVAL;
> }
> @@ -410,6 +467,11 @@ static int tree_copy(struct landlock_ruleset *const parent,
> &walker_rule->layers, walker_rule->num_layers,
> rule_type);
> break;
> + case LANDLOCK_RULE_NET_SERVICE:
> + err = insert_rule(child, NULL, walker_rule->object.data,
> + &walker_rule->layers, walker_rule->num_layers,
> + rule_type);
> + break;
> }
> if (err)
> return err;
> @@ -432,6 +494,10 @@ static int inherit_ruleset(struct landlock_ruleset *const parent,
>
> /* Copies the @parent inode tree. */
> err = tree_copy(parent, child, LANDLOCK_RULE_PATH_BENEATH);
> + if (err)
> + goto out_unlock;
> + /* Copies the @parent inode tree. */
> + err = tree_copy(parent, child, LANDLOCK_RULE_NET_SERVICE);
> if (err)
> goto out_unlock;
>
> @@ -464,6 +530,9 @@ static void free_ruleset(struct landlock_ruleset *const ruleset)
> rbtree_postorder_for_each_entry_safe(freeme, next, &ruleset->root_inode,
> node)
> free_rule(freeme, LANDLOCK_RULE_PATH_BENEATH);
> + rbtree_postorder_for_each_entry_safe(freeme, next, &ruleset->root_net_port,
> + node)
> + free_rule(freeme, LANDLOCK_RULE_NET_SERVICE);
> put_hierarchy(ruleset->hierarchy);
> kfree(ruleset);
> }
> @@ -565,6 +634,9 @@ const struct landlock_rule *landlock_find_rule(
> case LANDLOCK_RULE_PATH_BENEATH:
> node = ruleset->root_inode.rb_node;
> break;
> + case LANDLOCK_RULE_NET_SERVICE:
> + node = ruleset->root_net_port.rb_node;
> + break;
> default:
> return ERR_PTR(-EINVAL);
> }
> @@ -586,8 +658,8 @@ const struct landlock_rule *landlock_find_rule(
> /* Access-control management */
> u64 landlock_unmask_layers(const struct landlock_ruleset *const domain,
> const struct landlock_object *object_ptr,
> - const u32 access_request, u64 layer_mask,
> - const u16 rule_type)
> + const u16 port, const u32 access_request,
> + u64 layer_mask, const u16 rule_type)
> {
> const struct landlock_rule *rule;
> size_t i;
> @@ -600,6 +672,10 @@ u64 landlock_unmask_layers(const struct landlock_ruleset *const domain,
> LANDLOCK_RULE_PATH_BENEATH);
> rcu_read_unlock();
> break;
> + case LANDLOCK_RULE_NET_SERVICE:
> + rule = landlock_find_rule(domain, (uintptr_t)port,
Type casting should not be required.
[...]
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