Re: [PATCH v5 07/15] landlock: add support network rules

[Konstantin Meskhidze <konstantin.meskhidze@huawei.com>]

5/17/2022 11:27 AM, Mickaël Salaün пишет:
> 
> 
> On 16/05/2022 17:20, 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@huawei.com>
>> ---
>>
>> Changes since v3:
>> * Split commit.
>> * Add network rule support for internal landlock functions.
>> * Add set_mask and get_mask for network.
>> * Add rb_root root_net_port.
>>
>> Changes since v4:
>> * Refactoring landlock_create_ruleset() - splits ruleset and
>> masks checks.
>> * Refactoring landlock_create_ruleset() and landlock mask
>> setters/getters to support two rule types.
>> * Refactoring landlock_add_rule syscall add_rule_path_beneath
>> function by factoring out get_ruleset_from_fd() and
>> landlock_put_ruleset().
>>
>> ---
>>   security/landlock/limits.h   |  8 +++-
>>   security/landlock/ruleset.c  | 82 +++++++++++++++++++++++++++++++-----
>>   security/landlock/ruleset.h  | 34 +++++++++++++--
>>   security/landlock/syscalls.c | 45 +++++++++++---------
>>   4 files changed, 132 insertions(+), 37 deletions(-)
>>
>> diff --git a/security/landlock/limits.h b/security/landlock/limits.h
>> index b54184ab9439..23694bf05cb7 100644
>> --- a/security/landlock/limits.h
>> +++ b/security/landlock/limits.h
>> @@ -22,6 +22,12 @@
>>   #define LANDLOCK_MASK_ACCESS_FS        ((LANDLOCK_LAST_ACCESS_FS << 
>> 1) - 1)
>>   #define LANDLOCK_NUM_ACCESS_FS        
>> __const_hweight64(LANDLOCK_MASK_ACCESS_FS)
>>
>> -/* clang-format on */
>> +#define LANDLOCK_LAST_ACCESS_NET    LANDLOCK_ACCESS_NET_CONNECT_TCP
>> +#define LANDLOCK_MASK_ACCESS_NET    ((LANDLOCK_LAST_ACCESS_NET << 1) 
>> - 1)
>> +#define LANDLOCK_NUM_ACCESS_NET        
>> __const_hweight64(LANDLOCK_MASK_ACCESS_NET)
>> +#define LANDLOCK_MASK_SHIFT_NET        16
>> +
>> +#define LANDLOCK_RULE_TYPE_NUM        LANDLOCK_RULE_NET_SERVICE
>>
>> +/* clang-format on */
>>   #endif /* _SECURITY_LANDLOCK_LIMITS_H */
>> diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
>> index c4ed783d655b..ea9ecb3f471a 100644
>> --- a/security/landlock/ruleset.c
>> +++ b/security/landlock/ruleset.c
>> @@ -36,6 +36,7 @@ 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
>> @@ -46,17 +47,21 @@ static struct landlock_ruleset 
>> *create_ruleset(const u32 num_layers)
>>   }
>>
>>   struct landlock_ruleset *landlock_create_ruleset(
>> -        const access_mask_t access_mask)
>> +                    const access_mask_t access_mask_fs,
>> +                    const access_mask_t access_mask_net)
>>   {
>>       struct landlock_ruleset *new_ruleset;
>>
>>       /* Informs about useless ruleset. */
>> -    if (!access_mask)
>> +    if (!access_mask_fs && !access_mask_net)
>>           return ERR_PTR(-ENOMSG);
>>       new_ruleset = create_ruleset(1);
>> -    if (!IS_ERR(new_ruleset))
>> -        landlock_set_fs_access_mask(new_ruleset, access_mask, 0);
>> -
>> +    if (IS_ERR(new_ruleset))
>> +        return new_ruleset;
>> +    if (access_mask_fs)
>> +        landlock_set_fs_access_mask(new_ruleset, access_mask_fs, 0);
>> +    if (access_mask_net)
>> +        landlock_set_net_access_mask(new_ruleset, access_mask_net, 0);
>>       return new_ruleset;
>>   }
>>
>> @@ -94,9 +99,11 @@ static struct landlock_rule *create_rule(
>>           return ERR_PTR(-ENOMEM);
>>       RB_CLEAR_NODE(&new_rule->node);
>>
>> -    if (object_ptr) {
>> +    if (object_ptr && !object_data) {
>>           landlock_get_object(object_ptr);
>>           new_rule->object.ptr = object_ptr;
>> +    } else if (object_data && !object_ptr) {
>> +        new_rule->object.data = object_data;
>>       } else if (object_ptr && object_data) {
>>           WARN_ON_ONCE(1);
>>           return ERR_PTR(-EINVAL);
>> @@ -132,10 +139,12 @@ 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);
>>   }
>>
>>   /**
>> @@ -183,6 +192,11 @@ static int insert_rule(struct landlock_ruleset 
>> *const ruleset,
>>           object_data = (uintptr_t)object_ptr;
>>           root = &ruleset->root_inode;
>>           break;
>> +    case LANDLOCK_RULE_NET_SERVICE:
>> +        if (WARN_ON_ONCE(object_ptr))
>> +            return -EINVAL;
>> +        root = &ruleset->root_net_port;
>> +        break;
>>       default:
>>           WARN_ON_ONCE(1);
>>           return -EINVAL;
>> @@ -237,6 +251,16 @@ static int insert_rule(struct landlock_ruleset 
>> *const ruleset,
>>                       &ruleset->root_inode);
>>               free_rule(this, rule_type);
>>               break;
>> +        case LANDLOCK_RULE_NET_SERVICE:
>> +            new_rule = create_rule(NULL, object_data,
>> +                           &this->layers, this->num_layers,
>> +                           &(*layers)[0]);
>> +            if (IS_ERR(new_rule))
>> +                return PTR_ERR(new_rule);
>> +            rb_replace_node(&this->node, &new_rule->node,
>> +                    &ruleset->root_net_port);
>> +            free_rule(this, rule_type);
>> +            break;
>>           }
>>           return 0;
>>       }
>> @@ -254,6 +278,15 @@ static int insert_rule(struct landlock_ruleset 
>> *const ruleset,
>>           rb_link_node(&new_rule->node, parent_node, walker_node);
>>           rb_insert_color(&new_rule->node, &ruleset->root_inode);
>>           break;
>> +    case LANDLOCK_RULE_NET_SERVICE:
>> +        new_rule = create_rule(NULL, object_data, layers,
>> +                       num_layers, NULL);
>> +        if (IS_ERR(new_rule))
>> +            return PTR_ERR(new_rule);
>> +        rb_link_node(&new_rule->node, parent_node, walker_node);
>> +        rb_insert_color(&new_rule->node, &ruleset->root_net_port);
>> +        ruleset->num_rules++;
>> +        break;
>>       }
>>       return 0;
>>   }
>> @@ -315,6 +348,9 @@ 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;
>>       }
>> @@ -341,6 +377,11 @@ static int tree_merge(struct landlock_ruleset 
>> *const src,
>>                         rule_type, &layers,
>>                         ARRAY_SIZE(layers));
>>               break;
>> +        case LANDLOCK_RULE_NET_SERVICE:
>> +            err = insert_rule(dst, NULL, walker_rule->object.data,
>> +                      rule_type, &layers,
>> +                      ARRAY_SIZE(layers));
>> +            break;
>>           }
>>           if (err)
>>               return err;
>> @@ -376,6 +417,10 @@ 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);
>> @@ -395,6 +440,9 @@ 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;
>>       }
>> @@ -407,6 +455,12 @@ static int tree_copy(struct landlock_ruleset 
>> *const parent,
>>                         rule_type, &walker_rule->layers,
>>                         walker_rule->num_layers);
>>               break;
>> +        case LANDLOCK_RULE_NET_SERVICE:
>> +            err = insert_rule(child, NULL,
>> +                      walker_rule->object.data, rule_type,
>> +                      &walker_rule->layers,
>> +                      walker_rule->num_layers);
>> +            break;
>>           }
>>           if (err)
>>               return err;
>> @@ -429,6 +483,10 @@ 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. */
> 
> Not the inode tree this time.

   Right. Thanks for noticing.
> 
> 
>> +    err = tree_copy(parent, child, LANDLOCK_RULE_NET_SERVICE);
>>       if (err)
>>           goto out_unlock;
>>
>> @@ -463,9 +521,11 @@ static void free_ruleset(struct landlock_ruleset 
>> *const ruleset)
>>
>>       might_sleep();
>>       rbtree_postorder_for_each_entry_safe(freeme, next,
>> -                         &ruleset->root_inode,
>> -                         node)
>> +                         &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);
>>   }
>> @@ -560,13 +620,13 @@ const struct landlock_rule *landlock_find_rule(
>>   {
>>       const struct rb_node *node;
>>
>> -    if (!object_data)
>> -        return NULL;
>> -
>>       switch (rule_type) {
>>       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:
>>           WARN_ON_ONCE(1);
>>           return NULL;
>> diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
>> index f3cd890d0348..916b30b31c06 100644
>> --- a/security/landlock/ruleset.h
>> +++ b/security/landlock/ruleset.h
>> @@ -102,6 +102,12 @@ struct landlock_ruleset {
>>        * tree is immutable until @usage reaches zero.
>>        */
>>       struct rb_root root_inode;
>> +    /**
>> +     * @root_net_port: Root of a red-black tree containing object nodes
>> +     * for network port. Once a ruleset is tied to a process (i.e. as 
>> a domain),
>> +     * this tree is immutable until @usage reaches zero.
>> +     */
>> +    struct rb_root root_net_port;
>>       /**
>>        * @hierarchy: Enables hierarchy identification even when a parent
>>        * domain vanishes.  This is needed for the ptrace protection.
>> @@ -157,7 +163,8 @@ struct landlock_ruleset {
>>   };
>>
>>   struct landlock_ruleset *landlock_create_ruleset(
>> -        const access_mask_t access_mask);
>> +                    const access_mask_t access_mask_fs,
>> +                    const access_mask_t access_mask_net);
>>
>>   void landlock_put_ruleset(struct landlock_ruleset *const ruleset);
>>   void landlock_put_ruleset_deferred(struct landlock_ruleset *const 
>> ruleset);
>> @@ -183,11 +190,12 @@ static inline void landlock_get_ruleset(struct 
>> landlock_ruleset *const ruleset)
>>   }
>>
>>   /* 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,
>> +static inline void landlock_set_fs_access_mask(
>> +                 struct landlock_ruleset *ruleset,
>> +                 const access_mask_t access_mask_fs,
>>                    u16 mask_level)
>>   {
>> -    ruleset->access_masks[mask_level] = access_maskset;
>> +    ruleset->access_masks[mask_level] = access_mask_fs;
>>   }
>>
>>   /* A helper function to get a filesystem mask */
>> @@ -198,6 +206,24 @@ static inline u32 landlock_get_fs_access_mask(
>>       return (ruleset->access_masks[mask_level] & 
>> LANDLOCK_MASK_ACCESS_FS);
>>   }
>>
>> +/* A helper function to set a network mask */
>> +static inline void landlock_set_net_access_mask(
>> +                  struct landlock_ruleset *ruleset,
>> +                  const access_mask_t access_mask_net,
>> +                  u16 mask_level)
>> +{
>> +    ruleset->access_masks[mask_level] |= (access_mask_net <<
>> +                          LANDLOCK_MASK_SHIFT_NET);
>> +}
>> +
>> +/* A helper function to get a network mask */
>> +static inline u32 landlock_get_net_access_mask(
>> +                const struct landlock_ruleset *ruleset,
>> +                u16 mask_level)
>> +{
>> +    return (ruleset->access_masks[mask_level] >> 
>> LANDLOCK_MASK_SHIFT_NET);
>> +}
>> +
>>   access_mask_t get_handled_accesses(
>>           const struct landlock_ruleset *const domain,
>>           u16 rule_type, u16 num_access);
>> diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
>> index 31f9facec123..812541f4e155 100644
>> --- a/security/landlock/syscalls.c
>> +++ b/security/landlock/syscalls.c
>> @@ -189,8 +189,14 @@ SYSCALL_DEFINE3(landlock_create_ruleset,
>>           LANDLOCK_MASK_ACCESS_FS)
>>           return -EINVAL;
>>
>> +    /* Checks network content (and 32-bits cast). */
>> +    if ((ruleset_attr.handled_access_net | LANDLOCK_MASK_ACCESS_NET) !=
>> +            LANDLOCK_MASK_ACCESS_NET)
>> +        return -EINVAL;
>> +
>>       /* Checks arguments and transforms to kernel struct. */
>> -    ruleset = landlock_create_ruleset(ruleset_attr.handled_access_fs);
>> +    ruleset = landlock_create_ruleset(ruleset_attr.handled_access_fs,
>> +                      ruleset_attr.handled_access_net);
>>       if (IS_ERR(ruleset))
>>           return PTR_ERR(ruleset);
>>
>> @@ -275,21 +281,17 @@ static int get_path_from_fd(const s32 fd, struct 
>> path *const path)
>>       return err;
>>   }
>>
>> -static int add_rule_path_beneath(const int ruleset_fd, const void 
>> *const rule_attr)
>> +static int add_rule_path_beneath(struct landlock_ruleset *const ruleset,
>> +                 const void *const rule_attr)
>>   {
>>       struct landlock_path_beneath_attr path_beneath_attr;
>>       struct path path;
>> -    struct landlock_ruleset *ruleset;
>>       int res, err;
>> -
>> -    /* Gets and checks the ruleset. */
>> -    ruleset = get_ruleset_from_fd(ruleset_fd, FMODE_CAN_WRITE);
>> -    if (IS_ERR(ruleset))
>> -        return PTR_ERR(ruleset);
>> +    u32 mask;
>>
>>       /* Copies raw user space buffer, only one type for now. */
>>       res = copy_from_user(&path_beneath_attr, rule_attr,
>> -                sizeof(path_beneath_attr));
>> +            sizeof(path_beneath_attr));
>>       if (res)
>>           return -EFAULT;
>>
>> @@ -298,32 +300,26 @@ static int add_rule_path_beneath(const int 
>> ruleset_fd, const void *const rule_at
>>        * are ignored in path walks.
>>        */
>>       if (!path_beneath_attr.allowed_access) {
>> -        err = -ENOMSG;
>> -        goto out_put_ruleset;
>> +        return -ENOMSG;
>>       }
>>       /*
>>        * Checks that allowed_access matches the @ruleset constraints
>>        * (ruleset->access_masks[0] is automatically upgraded to 64-bits).
>>        */
>> -    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;
>> -    }
>> +    mask = landlock_get_fs_access_mask(ruleset, 0);
>> +    if ((path_beneath_attr.allowed_access | mask) != mask)
>> +        return -EINVAL;
>>
>>       /* Gets and checks the new rule. */
>>       err = get_path_from_fd(path_beneath_attr.parent_fd, &path);
>>       if (err)
>> -        goto out_put_ruleset;
>> +        return err;
>>
>>       /* Imports the new rule. */
>>       err = landlock_append_fs_rule(ruleset, &path,
>>                         path_beneath_attr.allowed_access);
>>       path_put(&path);
>>
>> -out_put_ruleset:
>> -    landlock_put_ruleset(ruleset);
>>       return err;
>>   }
>>
>> @@ -360,6 +356,7 @@ SYSCALL_DEFINE4(landlock_add_rule,
>>           const int, ruleset_fd, const enum landlock_rule_type, 
>> rule_type,
>>           const void __user *const, rule_attr, const __u32, flags)
>>   {
>> +    struct landlock_ruleset *ruleset;
>>       int err;
>>
>>       if (!landlock_initialized)
>> @@ -369,14 +366,20 @@ SYSCALL_DEFINE4(landlock_add_rule,
>>       if (flags)
>>           return -EINVAL;
>>
>> +    /* Gets and checks the ruleset. */
>> +    ruleset = get_ruleset_from_fd(ruleset_fd, FMODE_CAN_WRITE);
>> +    if (IS_ERR(ruleset))
>> +        return PTR_ERR(ruleset);
> 
> This shouldn't be part of this patch.
> 
   I agree. I will move it into another patch.
> 
>> +
>>       switch (rule_type) {
>>       case LANDLOCK_RULE_PATH_BENEATH:
>> -        err = add_rule_path_beneath(ruleset_fd, rule_attr);
>> +        err = add_rule_path_beneath(ruleset, rule_attr);
>>           break;
>>       default:
>>           err = -EINVAL;
>>           break;
>>       }
>> +    landlock_put_ruleset(ruleset);
>>       return err;
>>   }
>>
>> -- 
>> 2.25.1
>>
> .