* Add new landlock rule type that corresponds to the restriction of socket protocols. This is represented as an landlock_socket_attr structure. Protocol allowed by landlock must be described by a family-type pair (see socket(2)). * Support socket rule storage in landlock ruleset. * Add flag LANDLOCK_ACCESS_SOCKET_CREATE that will provide the ability to control socket creation. * Add socket.c file that will contain socket rules management and hooks. Implement helper pack_socket_key() to convert 32-bit family and type values into uintptr_t. This is possible due to the fact that these values are limited to AF_MAX (=46), SOCK_MAX (=11) constants. Assumption is checked in build-time by the helper. * Support socket rules in landlock syscalls. Change ABI version to 6. Closes: https://github.com/landlock-lsm/linux/issues/6 Signed-off-by: Mikhail Ivanov <ivanov.mikhail1@xxxxxxxxxxxxxxxxxxx> --- Changes since v1: * Reverts landlock_key.data type from u64 to uinptr_t. * Adds helper to pack domain and type values into uintptr_t. * Denies inserting socket rule with invalid family and type. * Renames 'domain' to 'family' in landlock_socket_attr. * Updates ABI version to 6 since ioctl patches changed it to 5. * Formats code with clang-format. * Minor fixes. --- include/uapi/linux/landlock.h | 53 +++++++++++++++- security/landlock/Makefile | 2 +- security/landlock/limits.h | 5 ++ security/landlock/ruleset.c | 37 ++++++++++- security/landlock/ruleset.h | 41 +++++++++++- security/landlock/socket.c | 60 ++++++++++++++++++ security/landlock/socket.h | 17 +++++ security/landlock/syscalls.c | 66 ++++++++++++++++++-- tools/testing/selftests/landlock/base_test.c | 2 +- 9 files changed, 272 insertions(+), 11 deletions(-) create mode 100644 security/landlock/socket.c create mode 100644 security/landlock/socket.h diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h index 68625e728f43..a25ba5983dfb 100644 --- a/include/uapi/linux/landlock.h +++ b/include/uapi/linux/landlock.h @@ -37,6 +37,13 @@ struct landlock_ruleset_attr { * rule explicitly allow them. */ __u64 handled_access_net; + + /** + * @handled_access_socket: Bitmask of actions (cf. `Socket flags`_) + * that is handled by this ruleset and should then be forbidden if no + * rule explicitly allow them. + */ + __u64 handled_access_socket; }; /* @@ -65,6 +72,11 @@ enum landlock_rule_type { * landlock_net_port_attr . */ LANDLOCK_RULE_NET_PORT, + /** + * @LANDLOCK_RULE_SOCKET: Type of a &struct + * landlock_socket_attr . + */ + LANDLOCK_RULE_SOCKET, }; /** @@ -115,6 +127,28 @@ struct landlock_net_port_attr { __u64 port; }; +/** + * struct landlock_socket_attr - Socket definition + * + * Argument of sys_landlock_add_rule(). + */ +struct landlock_socket_attr { + /** + * @allowed_access: Bitmask of allowed access for a socket + * (cf. `Socket flags`_). + */ + __u64 allowed_access; + /** + * @family: Protocol family used for communication + * (same as domain in socket(2)). + */ + int family; + /** + * @type: Socket type (see socket(2)). + */ + int type; +}; + /** * DOC: fs_access * @@ -251,7 +285,7 @@ struct landlock_net_port_attr { * DOC: net_access * * Network flags - * ~~~~~~~~~~~~~~~~ + * ~~~~~~~~~~~~~ * * These flags enable to restrict a sandboxed process to a set of network * actions. This is supported since the Landlock ABI version 4. @@ -266,4 +300,21 @@ struct landlock_net_port_attr { #define LANDLOCK_ACCESS_NET_BIND_TCP (1ULL << 0) #define LANDLOCK_ACCESS_NET_CONNECT_TCP (1ULL << 1) /* clang-format on */ + +/** + * DOC: socket_access + * + * Socket flags + * ~~~~~~~~~~~~ + * + * These flags enable to restrict a sanboxed process to a set of socket + * protocols. This is supported since the Landlock ABI version 6. + * + * The following access rights apply only to sockets: + * + * - %LANDLOCK_ACCESS_SOCKET_CREATE: Create a socket. + */ +/* clang-format off */ +#define LANDLOCK_ACCESS_SOCKET_CREATE (1ULL << 0) +/* clang-format on */ #endif /* _UAPI_LINUX_LANDLOCK_H */ diff --git a/security/landlock/Makefile b/security/landlock/Makefile index b4538b7cf7d2..ff1dd98f6a1b 100644 --- a/security/landlock/Makefile +++ b/security/landlock/Makefile @@ -1,6 +1,6 @@ obj-$(CONFIG_SECURITY_LANDLOCK) := landlock.o landlock-y := setup.o syscalls.o object.o ruleset.o \ - cred.o task.o fs.o + cred.o task.o fs.o socket.o landlock-$(CONFIG_INET) += net.o diff --git a/security/landlock/limits.h b/security/landlock/limits.h index 20fdb5ff3514..448b4d596783 100644 --- a/security/landlock/limits.h +++ b/security/landlock/limits.h @@ -28,6 +28,11 @@ #define LANDLOCK_NUM_ACCESS_NET __const_hweight64(LANDLOCK_MASK_ACCESS_NET) #define LANDLOCK_SHIFT_ACCESS_NET LANDLOCK_NUM_ACCESS_FS +#define LANDLOCK_LAST_ACCESS_SOCKET LANDLOCK_ACCESS_SOCKET_CREATE +#define LANDLOCK_MASK_ACCESS_SOCKET ((LANDLOCK_LAST_ACCESS_SOCKET << 1) - 1) +#define LANDLOCK_NUM_ACCESS_SOCKET __const_hweight64(LANDLOCK_MASK_ACCESS_SOCKET) +#define LANDLOCK_SHIFT_ACCESS_SOCKET LANDLOCK_NUM_ACCESS_SOCKET + /* clang-format on */ #endif /* _SECURITY_LANDLOCK_LIMITS_H */ diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c index e0a5fbf9201a..c782f7cd313d 100644 --- a/security/landlock/ruleset.c +++ b/security/landlock/ruleset.c @@ -40,6 +40,7 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers) #if IS_ENABLED(CONFIG_INET) new_ruleset->root_net_port = RB_ROOT; #endif /* IS_ENABLED(CONFIG_INET) */ + new_ruleset->root_socket = RB_ROOT; new_ruleset->num_layers = num_layers; /* @@ -52,12 +53,13 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers) struct landlock_ruleset * landlock_create_ruleset(const access_mask_t fs_access_mask, - const access_mask_t net_access_mask) + const access_mask_t net_access_mask, + const access_mask_t socket_access_mask) { struct landlock_ruleset *new_ruleset; /* Informs about useless ruleset. */ - if (!fs_access_mask && !net_access_mask) + if (!fs_access_mask && !net_access_mask && !socket_access_mask) return ERR_PTR(-ENOMSG); new_ruleset = create_ruleset(1); if (IS_ERR(new_ruleset)) @@ -66,6 +68,9 @@ landlock_create_ruleset(const access_mask_t fs_access_mask, landlock_add_fs_access_mask(new_ruleset, fs_access_mask, 0); if (net_access_mask) landlock_add_net_access_mask(new_ruleset, net_access_mask, 0); + if (socket_access_mask) + landlock_add_socket_access_mask(new_ruleset, socket_access_mask, + 0); return new_ruleset; } @@ -89,6 +94,9 @@ static bool is_object_pointer(const enum landlock_key_type key_type) return false; #endif /* IS_ENABLED(CONFIG_INET) */ + case LANDLOCK_KEY_SOCKET: + return false; + default: WARN_ON_ONCE(1); return false; @@ -146,6 +154,9 @@ static struct rb_root *get_root(struct landlock_ruleset *const ruleset, return &ruleset->root_net_port; #endif /* IS_ENABLED(CONFIG_INET) */ + case LANDLOCK_KEY_SOCKET: + return &ruleset->root_socket; + default: WARN_ON_ONCE(1); return ERR_PTR(-EINVAL); @@ -175,7 +186,9 @@ static void build_check_ruleset(void) BUILD_BUG_ON(ruleset.num_layers < LANDLOCK_MAX_NUM_LAYERS); BUILD_BUG_ON(access_masks < ((LANDLOCK_MASK_ACCESS_FS << LANDLOCK_SHIFT_ACCESS_FS) | - (LANDLOCK_MASK_ACCESS_NET << LANDLOCK_SHIFT_ACCESS_NET))); + (LANDLOCK_MASK_ACCESS_NET << LANDLOCK_SHIFT_ACCESS_NET) | + (LANDLOCK_MASK_ACCESS_SOCKET + << LANDLOCK_SHIFT_ACCESS_SOCKET))); } /** @@ -399,6 +412,11 @@ static int merge_ruleset(struct landlock_ruleset *const dst, goto out_unlock; #endif /* IS_ENABLED(CONFIG_INET) */ + /* Merges the @src socket tree. */ + err = merge_tree(dst, src, LANDLOCK_KEY_SOCKET); + if (err) + goto out_unlock; + out_unlock: mutex_unlock(&src->lock); mutex_unlock(&dst->lock); @@ -462,6 +480,11 @@ static int inherit_ruleset(struct landlock_ruleset *const parent, goto out_unlock; #endif /* IS_ENABLED(CONFIG_INET) */ + /* Copies the @parent socket tree. */ + err = inherit_tree(parent, child, LANDLOCK_KEY_SOCKET); + if (err) + goto out_unlock; + if (WARN_ON_ONCE(child->num_layers <= parent->num_layers)) { err = -EINVAL; goto out_unlock; @@ -498,6 +521,10 @@ static void free_ruleset(struct landlock_ruleset *const ruleset) free_rule(freeme, LANDLOCK_KEY_NET_PORT); #endif /* IS_ENABLED(CONFIG_INET) */ + rbtree_postorder_for_each_entry_safe(freeme, next, + &ruleset->root_socket, node) + free_rule(freeme, LANDLOCK_KEY_SOCKET); + put_hierarchy(ruleset->hierarchy); kfree(ruleset); } @@ -708,6 +735,10 @@ landlock_init_layer_masks(const struct landlock_ruleset *const domain, break; #endif /* IS_ENABLED(CONFIG_INET) */ + case LANDLOCK_KEY_SOCKET: + get_access_mask = landlock_get_socket_access_mask; + num_access = LANDLOCK_NUM_ACCESS_SOCKET; + break; default: WARN_ON_ONCE(1); return 0; diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h index c7f1526784fd..a9773efd529b 100644 --- a/security/landlock/ruleset.h +++ b/security/landlock/ruleset.h @@ -92,6 +92,12 @@ enum landlock_key_type { * node keys. */ LANDLOCK_KEY_NET_PORT, + + /** + * @LANDLOCK_KEY_SOCKET: Type of &landlock_ruleset.root_socket's + * node keys. + */ + LANDLOCK_KEY_SOCKET, }; /** @@ -177,6 +183,15 @@ struct landlock_ruleset { struct rb_root root_net_port; #endif /* IS_ENABLED(CONFIG_INET) */ + /** + * @root_socket: Root of a red-black tree containing &struct + * landlock_rule nodes with socket type, described by (family, type) + * pair (see socket(2)). 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_socket; + /** * @hierarchy: Enables hierarchy identification even when a parent * domain vanishes. This is needed for the ptrace protection. @@ -233,7 +248,8 @@ struct landlock_ruleset { struct landlock_ruleset * landlock_create_ruleset(const access_mask_t access_mask_fs, - const access_mask_t access_mask_net); + const access_mask_t access_mask_net, + const access_mask_t access_mask_socket); void landlock_put_ruleset(struct landlock_ruleset *const ruleset); void landlock_put_ruleset_deferred(struct landlock_ruleset *const ruleset); @@ -282,6 +298,20 @@ landlock_add_net_access_mask(struct landlock_ruleset *const ruleset, (net_mask << LANDLOCK_SHIFT_ACCESS_NET); } +static inline void +landlock_add_socket_access_mask(struct landlock_ruleset *const ruleset, + const access_mask_t socket_access_mask, + const u16 layer_level) +{ + access_mask_t socket_mask = socket_access_mask & + LANDLOCK_MASK_ACCESS_SOCKET; + + /* Should already be checked in sys_landlock_create_ruleset(). */ + WARN_ON_ONCE(socket_access_mask != socket_mask); + ruleset->access_masks[layer_level] |= + (socket_mask << LANDLOCK_SHIFT_ACCESS_SOCKET); +} + static inline access_mask_t landlock_get_raw_fs_access_mask(const struct landlock_ruleset *const ruleset, const u16 layer_level) @@ -309,6 +339,15 @@ landlock_get_net_access_mask(const struct landlock_ruleset *const ruleset, LANDLOCK_MASK_ACCESS_NET; } +static inline access_mask_t +landlock_get_socket_access_mask(const struct landlock_ruleset *const ruleset, + const u16 layer_level) +{ + return (ruleset->access_masks[layer_level] >> + LANDLOCK_SHIFT_ACCESS_SOCKET) & + LANDLOCK_MASK_ACCESS_SOCKET; +} + bool landlock_unmask_layers(const struct landlock_rule *const rule, const access_mask_t access_request, layer_mask_t (*const layer_masks)[], diff --git a/security/landlock/socket.c b/security/landlock/socket.c new file mode 100644 index 000000000000..1249a4a36503 --- /dev/null +++ b/security/landlock/socket.c @@ -0,0 +1,60 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Landlock LSM - Socket management and hooks + * + * Copyright © 2024 Huawei Tech. Co., Ltd. + */ + +#include <linux/net.h> +#include <linux/socket.h> +#include <linux/stddef.h> + +#include "limits.h" +#include "ruleset.h" +#include "socket.h" + +static uintptr_t pack_socket_key(const int family, const int type) +{ + union { + struct { + unsigned short family, type; + } __packed data; + uintptr_t packed; + } socket_key; + + /* Checks that all supported socket families and types can be stored in socket_key. */ + BUILD_BUG_ON(AF_MAX > (typeof(socket_key.data.family))~0); + BUILD_BUG_ON(SOCK_MAX > (typeof(socket_key.data.type))~0); + + /* Checks that socket_key can be stored in landlock_key. */ + BUILD_BUG_ON(sizeof(socket_key.data) > sizeof(socket_key.packed)); + BUILD_BUG_ON(sizeof(socket_key.packed) > + sizeof_field(union landlock_key, data)); + + socket_key.data.family = (unsigned short)family; + socket_key.data.type = (unsigned short)type; + + return socket_key.packed; +} + +int landlock_append_socket_rule(struct landlock_ruleset *const ruleset, + const int family, const int type, + access_mask_t access_rights) +{ + int err; + + const struct landlock_id id = { + .key.data = pack_socket_key(family, type), + .type = LANDLOCK_KEY_SOCKET, + }; + + /* Transforms relative access rights to absolute ones. */ + access_rights |= LANDLOCK_MASK_ACCESS_SOCKET & + ~landlock_get_socket_access_mask(ruleset, 0); + + mutex_lock(&ruleset->lock); + err = landlock_insert_rule(ruleset, id, access_rights); + mutex_unlock(&ruleset->lock); + + return err; +} diff --git a/security/landlock/socket.h b/security/landlock/socket.h new file mode 100644 index 000000000000..8519357f1c39 --- /dev/null +++ b/security/landlock/socket.h @@ -0,0 +1,17 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Landlock LSM - Socket management and hooks + * + * Copyright © 2024 Huawei Tech. Co., Ltd. + */ + +#ifndef _SECURITY_LANDLOCK_SOCKET_H +#define _SECURITY_LANDLOCK_SOCKET_H + +#include "ruleset.h" + +int landlock_append_socket_rule(struct landlock_ruleset *const ruleset, + const int family, const int type, + access_mask_t access_rights); + +#endif /* _SECURITY_LANDLOCK_SOCKET_H */ diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c index 03b470f5a85a..30c771f5e74f 100644 --- a/security/landlock/syscalls.c +++ b/security/landlock/syscalls.c @@ -24,12 +24,14 @@ #include <linux/syscalls.h> #include <linux/types.h> #include <linux/uaccess.h> +#include <linux/net.h> #include <uapi/linux/landlock.h> #include "cred.h" #include "fs.h" #include "limits.h" #include "net.h" +#include "socket.h" #include "ruleset.h" #include "setup.h" @@ -88,7 +90,8 @@ static void build_check_abi(void) struct landlock_ruleset_attr ruleset_attr; struct landlock_path_beneath_attr path_beneath_attr; struct landlock_net_port_attr net_port_attr; - size_t ruleset_size, path_beneath_size, net_port_size; + struct landlock_socket_attr socket_attr; + size_t ruleset_size, path_beneath_size, net_port_size, socket_size; /* * For each user space ABI structures, first checks that there is no @@ -97,8 +100,9 @@ static void build_check_abi(void) */ ruleset_size = sizeof(ruleset_attr.handled_access_fs); ruleset_size += sizeof(ruleset_attr.handled_access_net); + ruleset_size += sizeof(ruleset_attr.handled_access_socket); BUILD_BUG_ON(sizeof(ruleset_attr) != ruleset_size); - BUILD_BUG_ON(sizeof(ruleset_attr) != 16); + BUILD_BUG_ON(sizeof(ruleset_attr) != 24); path_beneath_size = sizeof(path_beneath_attr.allowed_access); path_beneath_size += sizeof(path_beneath_attr.parent_fd); @@ -109,6 +113,12 @@ static void build_check_abi(void) net_port_size += sizeof(net_port_attr.port); BUILD_BUG_ON(sizeof(net_port_attr) != net_port_size); BUILD_BUG_ON(sizeof(net_port_attr) != 16); + + socket_size = sizeof(socket_attr.allowed_access); + socket_size += sizeof(socket_attr.family); + socket_size += sizeof(socket_attr.type); + BUILD_BUG_ON(sizeof(socket_attr) != socket_size); + BUILD_BUG_ON(sizeof(socket_attr) != 16); } /* Ruleset handling */ @@ -149,7 +159,7 @@ static const struct file_operations ruleset_fops = { .write = fop_dummy_write, }; -#define LANDLOCK_ABI_VERSION 5 +#define LANDLOCK_ABI_VERSION 6 /** * sys_landlock_create_ruleset - Create a new ruleset @@ -213,9 +223,15 @@ SYSCALL_DEFINE3(landlock_create_ruleset, LANDLOCK_MASK_ACCESS_NET) return -EINVAL; + /* Checks socket content (and 32-bits cast). */ + if ((ruleset_attr.handled_access_socket | + LANDLOCK_MASK_ACCESS_SOCKET) != LANDLOCK_MASK_ACCESS_SOCKET) + return -EINVAL; + /* Checks arguments and transforms to kernel struct. */ ruleset = landlock_create_ruleset(ruleset_attr.handled_access_fs, - ruleset_attr.handled_access_net); + ruleset_attr.handled_access_net, + ruleset_attr.handled_access_socket); if (IS_ERR(ruleset)) return PTR_ERR(ruleset); @@ -371,6 +387,45 @@ static int add_rule_net_port(struct landlock_ruleset *ruleset, net_port_attr.allowed_access); } +static int add_rule_socket(struct landlock_ruleset *ruleset, + const void __user *const rule_attr) +{ + struct landlock_socket_attr socket_attr; + int family, type; + int res; + access_mask_t mask; + + /* Copies raw user space buffer. */ + res = copy_from_user(&socket_attr, rule_attr, sizeof(socket_attr)); + if (res) + return -EFAULT; + + /* + * Informs about useless rule: empty allowed_access (i.e. deny rules) + * are ignored by socket actions. + */ + if (!socket_attr.allowed_access) + return -ENOMSG; + + /* Checks that allowed_access matches the @ruleset constraints. */ + mask = landlock_get_socket_access_mask(ruleset, 0); + if ((socket_attr.allowed_access | mask) != mask) + return -EINVAL; + + family = socket_attr.family; + type = socket_attr.type; + + /* Denies inserting a rule with unsupported socket family and type. */ + if (family < 0 || family >= AF_MAX) + return -EINVAL; + if (type < 0 || type >= SOCK_MAX) + return -EINVAL; + + /* Imports the new rule. */ + return landlock_append_socket_rule(ruleset, family, type, + socket_attr.allowed_access); +} + /** * sys_landlock_add_rule - Add a new rule to a ruleset * @@ -429,6 +484,9 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd, case LANDLOCK_RULE_NET_PORT: err = add_rule_net_port(ruleset, rule_attr); break; + case LANDLOCK_RULE_SOCKET: + err = add_rule_socket(ruleset, rule_attr); + break; default: err = -EINVAL; break; diff --git a/tools/testing/selftests/landlock/base_test.c b/tools/testing/selftests/landlock/base_test.c index 3c1e9f35b531..52b00472a487 100644 --- a/tools/testing/selftests/landlock/base_test.c +++ b/tools/testing/selftests/landlock/base_test.c @@ -75,7 +75,7 @@ TEST(abi_version) const struct landlock_ruleset_attr ruleset_attr = { .handled_access_fs = LANDLOCK_ACCESS_FS_READ_FILE, }; - ASSERT_EQ(5, landlock_create_ruleset(NULL, 0, + ASSERT_EQ(6, landlock_create_ruleset(NULL, 0, LANDLOCK_CREATE_RULESET_VERSION)); ASSERT_EQ(-1, landlock_create_ruleset(&ruleset_attr, 0, -- 2.34.1
