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

[Konstantin Meskhidze <konstantin.meskhidze@xxxxxxxxxx>]

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@xxxxxxxxxx>
> > ---
> >
> > 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
> .