4/16/2023 7:11 PM, Mickaël Salaün пишет:
On 23/03/2023 09:52, Konstantin Meskhidze wrote:This commit adds network rules support in the ruleset management helpers and the landlock_create_ruleset syscall. Refactor user space API to support network actions. Add new network access flags, network rule and network attributes. Increment Landlock ABI version. Expand access_masks_t to u32 to be sure network access rights can be stored. Implement socket_bind() and socket_connect() LSM hooks, which enable to restrict TCP socket binding and connection"which enables to"
Got it.
to specific ports. Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@xxxxxxxxxx> --- Changes since v9: * Changes UAPI port field to __u64. * Moves shared code into check_socket_access(). * Adds get_raw_handled_net_accesses() and get_current_net_domain() helpers. * Minor fixes. Changes since v8: * Squashes commits. * Refactors commit message. * Changes UAPI port field to __be16. * Changes logic of bind/connect hooks with AF_UNSPEC families. * Adds address length checking. * Minor fixes. Changes since v7: * Squashes commits. * Increments ABI version to 4. * Refactors commit message. * Minor fixes. Changes since v6: * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask() because it OR values. * Makes landlock_add_net_access_mask() more resilient incorrect values. * Refactors landlock_get_net_access_mask(). * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use LANDLOCK_NUM_ACCESS_FS as value. * Updates access_masks_t to u32 to support network access actions. * Refactors landlock internal functions to support network actions with landlock_key/key_type/id types. Changes since v5: * Gets rid of partial revert from landlock_add_rule syscall. * Formats code with clang-format-14. Changes since v4: * Refactors landlock_create_ruleset() - splits ruleset and masks checks. * Refactors landlock_create_ruleset() and landlock mask setters/getters to support two rule types. * Refactors landlock_add_rule syscall add_rule_path_beneath function by factoring out get_ruleset_from_fd() and landlock_put_ruleset(). Changes since v3: * Splits commit. * Adds network rule support for internal landlock functions. * Adds set_mask and get_mask for network. * Adds rb_root root_net_port. --- include/uapi/linux/landlock.h | 49 +++++ security/landlock/Kconfig | 1 + security/landlock/Makefile | 2 + security/landlock/limits.h | 6 +- security/landlock/net.c | 198 +++++++++++++++++++ security/landlock/net.h | 26 +++ security/landlock/ruleset.c | 52 ++++- security/landlock/ruleset.h | 63 +++++- security/landlock/setup.c | 2 + security/landlock/syscalls.c | 72 ++++++- tools/testing/selftests/landlock/base_test.c | 2 +- 11 files changed, 450 insertions(+), 23 deletions(-) create mode 100644 security/landlock/net.c create mode 100644 security/landlock/net.h diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h index 81d09ef9aa50..09b70fb6a9a6 100644 --- a/include/uapi/linux/landlock.h +++ b/include/uapi/linux/landlock.h @@ -31,6 +31,13 @@ struct landlock_ruleset_attr { * this access right. */ __u64 handled_access_fs; + + /** + * @handled_access_net: Bitmask of actions (cf. `Network flags`_) + * that is handled by this ruleset and should then be forbidden if no + * rule explicitly allow them. + */ + __u64 handled_access_net; }; /* @@ -54,6 +61,11 @@ enum landlock_rule_type { * landlock_path_beneath_attr . */ LANDLOCK_RULE_PATH_BENEATH = 1, + /** + * @LANDLOCK_RULE_NET_SERVICE: Type of a &struct + * landlock_net_service_attr . + */ + LANDLOCK_RULE_NET_SERVICE = 2, }; /** @@ -79,6 +91,24 @@ struct landlock_path_beneath_attr { */ } __attribute__((packed)); +/** + * struct landlock_net_service_attr - TCP subnet definition + * + * Argument of sys_landlock_add_rule(). + */ +struct landlock_net_service_attr { + /** + * @allowed_access: Bitmask of allowed access network for services + * (cf. `Network flags`_). + */ + __u64 allowed_access; + /** + * @port: Network port. + */ + __u64 port; + +} __attribute__((packed));You can remove the empty line and the packed attribute.
Ok. Thanks.
+ /** * DOC: fs_access * @@ -189,4 +219,23 @@ struct landlock_path_beneath_attr { #define LANDLOCK_ACCESS_FS_TRUNCATE (1ULL << 14) /* clang-format on */ +/** + * DOC: net_access + * + * Network flags + * ~~~~~~~~~~~~~~~~ + * + * These flags enable to restrict a sandboxed process to a set of network + * actions. + * + * TCP sockets with allowed actions: + * + * - %LANDLOCK_ACCESS_NET_BIND_TCP: Bind a TCP socket to a local port. + * - %LANDLOCK_ACCESS_NET_CONNECT_TCP: Connect an active TCP socket to + * a remote port. + */ +/* clang-format off */ +#define LANDLOCK_ACCESS_NET_BIND_TCP (1ULL << 0) +#define LANDLOCK_ACCESS_NET_CONNECT_TCP (1ULL << 1) +/* clang-format on */ #endif /* _UAPI_LINUX_LANDLOCK_H */ diff --git a/security/landlock/Kconfig b/security/landlock/Kconfig index 8e33c4e8ffb8..10c099097533 100644 --- a/security/landlock/Kconfig +++ b/security/landlock/Kconfig @@ -3,6 +3,7 @@ config SECURITY_LANDLOCK bool "Landlock support" depends on SECURITY && !ARCH_EPHEMERAL_INODES + select SECURITY_NETWORK select SECURITY_PATH help Landlock is a sandboxing mechanism that enables processes to restrict diff --git a/security/landlock/Makefile b/security/landlock/Makefile index 7bbd2f413b3e..53d3c92ae22e 100644 --- a/security/landlock/Makefile +++ b/security/landlock/Makefile @@ -2,3 +2,5 @@ obj-$(CONFIG_SECURITY_LANDLOCK) := landlock.o landlock-y := setup.o syscalls.o object.o ruleset.o \ cred.o ptrace.o fs.o + +landlock-$(CONFIG_INET) += net.o \ No newline at end of file diff --git a/security/landlock/limits.h b/security/landlock/limits.h index bafb3b8dc677..8a1a6463c64e 100644 --- a/security/landlock/limits.h +++ b/security/landlock/limits.h @@ -23,6 +23,10 @@ #define LANDLOCK_NUM_ACCESS_FS __const_hweight64(LANDLOCK_MASK_ACCESS_FS) #define LANDLOCK_SHIFT_ACCESS_FS 0 -/* 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_SHIFT_ACCESS_NET LANDLOCK_NUM_ACCESS_FS +/* clang-format on */ #endif /* _SECURITY_LANDLOCK_LIMITS_H */ diff --git a/security/landlock/net.c b/security/landlock/net.c new file mode 100644 index 000000000000..e19c339906e7 --- /dev/null +++ b/security/landlock/net.c @@ -0,0 +1,198 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Landlock LSM - Network management and hooks + * + * Copyright © 2022 Huawei Tech. Co., Ltd. + * Copyright © 2022 Microsoft Corporation + */ + +#include <linux/in.h> +#include <linux/net.h> +#include <linux/socket.h> +#include <net/ipv6.h> + +#include "common.h" +#include "cred.h" +#include "limits.h" +#include "net.h" +#include "ruleset.h" + +int landlock_append_net_rule(struct landlock_ruleset *const ruleset, + const u16 port, access_mask_t access_rights) +{ + int err; + const struct landlock_id id = { + .key.data = port, + .type = LANDLOCK_KEY_NET_PORT, + }; + BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data)); + + /* Transforms relative access rights to absolute ones. */ + access_rights |= LANDLOCK_MASK_ACCESS_NET & + ~landlock_get_net_access_mask(ruleset, 0); + + mutex_lock(&ruleset->lock); + err = landlock_insert_rule(ruleset, id, access_rights); + mutex_unlock(&ruleset->lock); + + return err; +} + +static access_mask_t +get_raw_handled_net_accesses(const struct landlock_ruleset *const domain) +{ + access_mask_t access_dom = 0; + size_t layer_level; + + for (layer_level = 0; layer_level < domain->num_layers; layer_level++) + access_dom |= landlock_get_net_access_mask(domain, layer_level); + return access_dom; +} + +static const struct landlock_ruleset *get_current_net_domain(void) +{ + const struct landlock_ruleset *const dom = + landlock_get_current_domain(); + + if (!dom || !get_raw_handled_net_accesses(dom)) + return NULL; + + return dom; +} + +static int check_addrlen(const struct sockaddr *const address, int addrlen) +{ + if (addrlen < offsetofend(struct sockaddr, sa_family)) + return -EINVAL; + switch (address->sa_family) { + case AF_UNSPEC: + case AF_INET: + if (addrlen < sizeof(struct sockaddr_in)) + return -EINVAL; + return 0; +#if IS_ENABLED(CONFIG_IPV6) + case AF_INET6: + if (addrlen < SIN6_LEN_RFC2133) + return -EINVAL; + return 0; +#endif + } + WARN_ON_ONCE(1); + return 0;With this code, using any non-TCP socket would print a warning.
Yep. Already got this warning printed in tests with unix sockets. I will refactor this part as you suggest below.
All these switch/case make difficult to check consistency across check_addrlen() and get_port() helpers, they should be inlined into check_socket_access(), with only one switch statement, but we need to be careful about the return error orders: first EINVAL and after EAFNOSUPPORT. Inlining all this also enables to get rid of impossible cases (that lead to these WARN_ON_ONCE calls).
Got it. Thanks.
+} + +static u16 get_port(const struct sockaddr *const address) +{ + /* Gets port value in host byte order. */ + switch (address->sa_family) { + case AF_UNSPEC: + case AF_INET: { + const struct sockaddr_in *const sockaddr = + (struct sockaddr_in *)address; + return ntohs(sockaddr->sin_port); + } +#if IS_ENABLED(CONFIG_IPV6) + case AF_INET6: { + const struct sockaddr_in6 *const sockaddr_ip6 = + (struct sockaddr_in6 *)address; + return ntohs(sockaddr_ip6->sin6_port); + } +#endif + } + WARN_ON_ONCE(1); + return 0; +} + +static int check_socket_access(struct socket *sock, struct sockaddr *address, int addrlen, u16 port, + access_mask_t access_request) +{ + int ret; + bool allowed = false; + layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {}; + const struct landlock_rule *rule; + access_mask_t handled_access; + const struct landlock_id id = { + .key.data = port, + .type = LANDLOCK_KEY_NET_PORT, + }; + const struct landlock_ruleset *const domain = get_current_net_domain(); + + if (WARN_ON_ONCE(!domain)) + return 0; + if (WARN_ON_ONCE(domain->num_layers < 1)) + return -EACCES; + /* Check if it's a TCP socket. */ + if (sock->type != SOCK_STREAM) + return 0; + + ret = check_addrlen(address, addrlen); + if (ret) + return ret;As explained above, this should be replaced with: if (addrlen < offsetofend(struct sockaddr, sa_family)) return -EINVAL;
Ok.
+ + switch (address->sa_family) {This below block should be moved after the generic switch statement (i.e. once port is checked).
Do you mean checking address family after a port has been checked??
+ case AF_UNSPEC: + /* + * Connecting to an address with AF_UNSPEC dissolves the TCP + * association, which have the same effect as closing the + * connection while retaining the socket object (i.e., the file + * descriptor). As for dropping privileges, closing + * connections is always allowed. + */ + if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) + return 0; + + /* + * For compatibility reason, accept AF_UNSPEC for bind + * accesses (mapped to AF_INET) only if the address is + * INADDR_ANY (cf. __inet_bind). Checking the address is + * required to not wrongfully return -EACCES instead of + * -EAFNOSUPPORT. + */ + if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) { + const struct sockaddr_in *const sockaddr = + (struct sockaddr_in *)address; + + if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY)) + return -EAFNOSUPPORT; + } + + fallthrough;case AF_UNSPEC:+ case AF_INET:if (addrlen < sizeof(struct sockaddr_in)) return -EINVAL; port = ((struct sockaddr_in *)address)->sin_port; break;+#if IS_ENABLED(CONFIG_IPV6) + case AF_INET6:if (addrlen < SIN6_LEN_RFC2133) return -EINVAL; port = ((struct sockaddr_in6 *)address)->sin6_port; break;+#endif/* Allows unhandled protocols. */ default: return 0; } if (address->sa_family == AF_UNSPEC) { // Add here the above AF_UNSPEC checks to be consistent with the EINVAL/EAFNOSUPPORT return ordering. } id.key.data = (__force uintprt_t)port; BUID_BUG_ON(...);
Will be refactored. Thanks.
+ rule = landlock_find_rule(domain, id); + handled_access = landlock_init_layer_masks( + domain, access_request, &layer_masks, + LANDLOCK_KEY_NET_PORT); + allowed = landlock_unmask_layers(rule, handled_access, + &layer_masks, + ARRAY_SIZE(layer_masks)); + }This curly brace can now be removed and the following return line is now OK.
Ok. Got it.
+ return allowed ? 0 : -EACCES; +} + +static int hook_socket_bind(struct socket *sock, struct sockaddr *address, + int addrlen) +{ + return check_socket_access(sock, address, addrlen, get_port(address), + LANDLOCK_ACCESS_NET_BIND_TCP); +} + +static int hook_socket_connect(struct socket *sock, struct sockaddr *address, + int addrlen) +{ + return check_socket_access(sock, address, addrlen, get_port(address), + LANDLOCK_ACCESS_NET_CONNECT_TCP); +} + +static struct security_hook_list landlock_hooks[] __lsm_ro_after_init = { + LSM_HOOK_INIT(socket_bind, hook_socket_bind), + LSM_HOOK_INIT(socket_connect, hook_socket_connect), +}; + +__init void landlock_add_net_hooks(void) +{ + security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks), + LANDLOCK_NAME); +} diff --git a/security/landlock/net.h b/security/landlock/net.h new file mode 100644 index 000000000000..0da1d9dff5ab --- /dev/null +++ b/security/landlock/net.h @@ -0,0 +1,26 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Landlock LSM - Network management and hooks + * + * Copyright © 2022 Huawei Tech. Co., Ltd. + */ + +#ifndef _SECURITY_LANDLOCK_NET_H +#define _SECURITY_LANDLOCK_NET_H + +#include "common.h" +#include "ruleset.h" +#include "setup.h" + +#if IS_ENABLED(CONFIG_INET) +__init void landlock_add_net_hooks(void); + +int landlock_append_net_rule(struct landlock_ruleset *const ruleset, + const u16 port, access_mask_t access_rights); +#else /* IS_ENABLED(CONFIG_INET) */ +static inline void landlock_add_net_hooks(void) +{ +} +#endif /* IS_ENABLED(CONFIG_INET) */ + +#endif /* _SECURITY_LANDLOCK_NET_H */ diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c index 14207b666095..53cb62701280 100644 --- a/security/landlock/ruleset.c +++ b/security/landlock/ruleset.c @@ -36,6 +36,9 @@ 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; +#if IS_ENABLED(CONFIG_INET) + new_ruleset->root_net_port = RB_ROOT; +#endif /* IS_ENABLED(CONFIG_INET) */ new_ruleset->num_layers = num_layers; /* * hierarchy = NULL @@ -46,16 +49,21 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers) } struct landlock_ruleset * -landlock_create_ruleset(const access_mask_t fs_access_mask) +landlock_create_ruleset(const access_mask_t fs_access_mask, + const access_mask_t net_access_mask) { struct landlock_ruleset *new_ruleset; /* Informs about useless ruleset. */ - if (!fs_access_mask) + if (!fs_access_mask && !net_access_mask) return ERR_PTR(-ENOMSG); new_ruleset = create_ruleset(1); - if (!IS_ERR(new_ruleset)) + if (IS_ERR(new_ruleset)) + return new_ruleset; + if (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); return new_ruleset; } @@ -73,6 +81,10 @@ static bool is_object_pointer(const enum landlock_key_type key_type) switch (key_type) { case LANDLOCK_KEY_INODE: return true; +#if IS_ENABLED(CONFIG_INET) + case LANDLOCK_KEY_NET_PORT: + return false; +#endif /* IS_ENABLED(CONFIG_INET) */ } WARN_ON_ONCE(1); return false; @@ -126,6 +138,11 @@ static struct rb_root *get_root(struct landlock_ruleset *const ruleset, case LANDLOCK_KEY_INODE: root = &ruleset->root_inode; break; +#if IS_ENABLED(CONFIG_INET) + case LANDLOCK_KEY_NET_PORT: + root = &ruleset->root_net_port; + break; +#endif /* IS_ENABLED(CONFIG_INET) */ } if (WARN_ON_ONCE(!root)) return ERR_PTR(-EINVAL); @@ -154,7 +171,8 @@ static void build_check_ruleset(void) BUILD_BUG_ON(ruleset.num_rules < LANDLOCK_MAX_NUM_RULES); 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_FS << LANDLOCK_SHIFT_ACCESS_FS) | + (LANDLOCK_MASK_ACCESS_NET << LANDLOCK_SHIFT_ACCESS_NET))); } /** @@ -373,6 +391,12 @@ static int merge_ruleset(struct landlock_ruleset *const dst, if (err) goto out_unlock; +#if IS_ENABLED(CONFIG_INET) + /* Merges the @src network port tree. */ + err = merge_tree(dst, src, LANDLOCK_KEY_NET_PORT); + if (err) + goto out_unlock; +#endif /* IS_ENABLED(CONFIG_INET) */ out_unlock: mutex_unlock(&src->lock); mutex_unlock(&dst->lock); @@ -429,6 +453,12 @@ static int inherit_ruleset(struct landlock_ruleset *const parent, if (err) goto out_unlock; +#if IS_ENABLED(CONFIG_INET) + /* Copies the @parent network port tree. */ + err = inherit_tree(parent, child, LANDLOCK_KEY_NET_PORT); + if (err) + goto out_unlock; +#endif /* IS_ENABLED(CONFIG_INET) */ if (WARN_ON_ONCE(child->num_layers <= parent->num_layers)) { err = -EINVAL; goto out_unlock; @@ -461,6 +491,11 @@ 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_KEY_INODE); +#if IS_ENABLED(CONFIG_INET) + rbtree_postorder_for_each_entry_safe(freeme, next, + &ruleset->root_net_port, node) + free_rule(freeme, LANDLOCK_KEY_NET_PORT); +#endif /* IS_ENABLED(CONFIG_INET) */ put_hierarchy(ruleset->hierarchy); kfree(ruleset); } @@ -641,7 +676,8 @@ get_access_mask_t(const struct landlock_ruleset *const ruleset, * * @domain: The domain that defines the current restrictions. * @access_request: The requested access rights to check. - * @layer_masks: The layer masks to populate. + * @layer_masks: It must contain LANDLOCK_NUM_ACCESS_FS or LANDLOCK_NUM_ACCESS_NET + * elements according to @key_type. * @key_type: The key type to switch between access masks of different types. * * Returns: An access mask where each access right bit is set which is handled @@ -662,6 +698,12 @@ landlock_init_layer_masks(const struct landlock_ruleset *const domain, get_access_mask = landlock_get_fs_access_mask; num_access = LANDLOCK_NUM_ACCESS_FS; break; +#if IS_ENABLED(CONFIG_INET) + case LANDLOCK_KEY_NET_PORT: + get_access_mask = landlock_get_net_access_mask; + num_access = LANDLOCK_NUM_ACCESS_NET; + break; +#endif /* IS_ENABLED(CONFIG_INET) */ default: WARN_ON_ONCE(1); return 0; diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h index 2251e6048ccf..dcf7fbac8367 100644 --- a/security/landlock/ruleset.h +++ b/security/landlock/ruleset.h @@ -33,13 +33,16 @@ typedef u16 access_mask_t; /* Makes sure all filesystem access rights can be stored. */ static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_FS); +/* Makes sure all network access rights can be stored. */ +static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_NET); /* 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; +typedef u32 access_masks_t; /* Makes sure all ruleset access rights can be stored. */ -static_assert(BITS_PER_TYPE(access_masks_t) >= LANDLOCK_NUM_ACCESS_FS); +static_assert(BITS_PER_TYPE(access_masks_t) >= + LANDLOCK_NUM_ACCESS_FS + LANDLOCK_NUM_ACCESS_NET); typedef u16 layer_mask_t; /* Makes sure all layers can be checked. */ @@ -84,6 +87,13 @@ enum landlock_key_type { * keys. */ LANDLOCK_KEY_INODE = 1, +#if IS_ENABLED(CONFIG_INET) + /** + * @LANDLOCK_KEY_NET_PORT: Type of &landlock_ruleset.root_net_port's + * node keys. + */ + LANDLOCK_KEY_NET_PORT = 2, +#endif /* IS_ENABLED(CONFIG_INET) */ }; /** @@ -158,6 +168,15 @@ struct landlock_ruleset { * reaches zero. */ struct rb_root root_inode; +#if IS_ENABLED(CONFIG_INET) + /** + * @root_net_port: Root of a red-black tree containing &struct + * landlock_rule nodes with 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; +#endif /* IS_ENABLED(CONFIG_INET) */ /** * @hierarchy: Enables hierarchy identification even when a parent * domain vanishes. This is needed for the ptrace protection. @@ -196,13 +215,13 @@ struct landlock_ruleset { */ u32 num_layers; /** - * @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 - * one. These layers are used when merging rulesets, - * for user space backward compatibility (i.e. - * future-proof), and to properly handle merged + * @access_masks: Contains the subset of filesystem and + * network 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 one. These layers are used when merging + * rulesets, for user space backward compatibility + * (i.e. future-proof), and to properly handle merged * rulesets without overlapping access rights. These * layers are set once and never changed for the * lifetime of the ruleset. @@ -213,7 +232,8 @@ struct landlock_ruleset { }; struct landlock_ruleset * -landlock_create_ruleset(const access_mask_t access_mask); +landlock_create_ruleset(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); @@ -249,6 +269,19 @@ landlock_add_fs_access_mask(struct landlock_ruleset *const ruleset, (fs_mask << LANDLOCK_SHIFT_ACCESS_FS); } +static inline void +landlock_add_net_access_mask(struct landlock_ruleset *const ruleset, + const access_mask_t net_access_mask, + const u16 layer_level) +{ + access_mask_t net_mask = net_access_mask & LANDLOCK_MASK_ACCESS_NET; + + /* Should already be checked in sys_landlock_create_ruleset(). */ + WARN_ON_ONCE(net_access_mask != net_mask); + ruleset->access_masks[layer_level] |= + (net_mask << LANDLOCK_SHIFT_ACCESS_NET); +} + static inline access_mask_t landlock_get_raw_fs_access_mask(const struct landlock_ruleset *const ruleset, const u16 layer_level) @@ -266,6 +299,16 @@ landlock_get_fs_access_mask(const struct landlock_ruleset *const ruleset, return landlock_get_raw_fs_access_mask(ruleset, layer_level) | LANDLOCK_ACCESS_FS_INITIALLY_DENIED; } + +static inline access_mask_t +landlock_get_net_access_mask(const struct landlock_ruleset *const ruleset, + const u16 layer_level) +{ + return (ruleset->access_masks[layer_level] >> + LANDLOCK_SHIFT_ACCESS_NET) & + LANDLOCK_MASK_ACCESS_NET; +} + 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/setup.c b/security/landlock/setup.c index 3f196d2ce4f9..7e4a598177b8 100644 --- a/security/landlock/setup.c +++ b/security/landlock/setup.c @@ -14,6 +14,7 @@ #include "fs.h" #include "ptrace.h" #include "setup.h" +#include "net.h" bool landlock_initialized __lsm_ro_after_init = false; @@ -29,6 +30,7 @@ static int __init landlock_init(void) landlock_add_cred_hooks(); landlock_add_ptrace_hooks(); landlock_add_fs_hooks(); + landlock_add_net_hooks(); landlock_initialized = true; pr_info("Up and running.\n"); return 0; diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c index 8a54e87dbb17..1f0edd605bc4 100644 --- a/security/landlock/syscalls.c +++ b/security/landlock/syscalls.c @@ -29,6 +29,7 @@ #include "cred.h" #include "fs.h" #include "limits.h" +#include "net.h" #include "ruleset.h" #include "setup.h" @@ -74,7 +75,8 @@ static void build_check_abi(void) { struct landlock_ruleset_attr ruleset_attr; struct landlock_path_beneath_attr path_beneath_attr; - size_t ruleset_size, path_beneath_size; + struct landlock_net_service_attr net_service_attr; + size_t ruleset_size, path_beneath_size, net_service_size; /* * For each user space ABI structures, first checks that there is no @@ -82,13 +84,19 @@ static void build_check_abi(void) * struct size. */ ruleset_size = sizeof(ruleset_attr.handled_access_fs); + ruleset_size += sizeof(ruleset_attr.handled_access_net); BUILD_BUG_ON(sizeof(ruleset_attr) != ruleset_size); - BUILD_BUG_ON(sizeof(ruleset_attr) != 8); + BUILD_BUG_ON(sizeof(ruleset_attr) != 16); path_beneath_size = sizeof(path_beneath_attr.allowed_access); path_beneath_size += sizeof(path_beneath_attr.parent_fd); BUILD_BUG_ON(sizeof(path_beneath_attr) != path_beneath_size); BUILD_BUG_ON(sizeof(path_beneath_attr) != 12); + + net_service_size = sizeof(net_service_attr.allowed_access); + net_service_size += sizeof(net_service_attr.port); + BUILD_BUG_ON(sizeof(net_service_attr) != net_service_size); + BUILD_BUG_ON(sizeof(net_service_attr) != 16); } /* Ruleset handling */ @@ -129,7 +137,7 @@ static const struct file_operations ruleset_fops = { .write = fop_dummy_write, }; -#define LANDLOCK_ABI_VERSION 3 +#define LANDLOCK_ABI_VERSION 4 /** * sys_landlock_create_ruleset - Create a new ruleset @@ -188,8 +196,14 @@ 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); @@ -315,13 +329,54 @@ static int add_rule_path_beneath(struct landlock_ruleset *const ruleset, return err; } +static int add_rule_net_service(struct landlock_ruleset *ruleset, + const void __user *const rule_attr) +{ +#if IS_ENABLED(CONFIG_INET) + struct landlock_net_service_attr net_service_attr; + int res; + access_mask_t mask; + + /* Copies raw user space buffer, only one type for now. */ + res = copy_from_user(&net_service_attr, rule_attr, + sizeof(net_service_attr)); + if (res) + return -EFAULT; + + /* + * Informs about useless rule: empty allowed_access (i.e. deny rules) + * are ignored by network actions. + */ + if (!net_service_attr.allowed_access) + return -ENOMSG; + + /* + * Checks that allowed_access matches the @ruleset constraints + * (ruleset->access_masks[0] is automatically upgraded to 64-bits). + */ + mask = landlock_get_net_access_mask(ruleset, 0); + if ((net_service_attr.allowed_access | mask) != mask) + return -EINVAL; + + /* Denies inserting a rule with port 0 or more than U16_MAX. */"Denies inserting a rule with port 0 or higher than 65535." A test should check that it works with 65535 but not with 65536.
Got it.
+ if ((net_service_attr.port == 0) || (net_service_attr.port > U16_MAX)) + return -EINVAL; + + /* Imports the new rule. */ + return landlock_append_net_rule(ruleset, net_service_attr.port, + net_service_attr.allowed_access); +#else /* IS_ENABLED(CONFIG_INET) */ + return -EAFNOSUPPORT; +#endif /* IS_ENABLED(CONFIG_INET) */ +} + /** * sys_landlock_add_rule - Add a new rule to a ruleset * * @ruleset_fd: File descriptor tied to the ruleset that should be extended * with the new rule. - * @rule_type: Identify the structure type pointed to by @rule_attr (only - * %LANDLOCK_RULE_PATH_BENEATH for now). + * @rule_type: Identify the structure type pointed to by @rule_attr: + * %LANDLOCK_RULE_PATH_BENEATH or %LANDLOCK_RULE_NET_SERVICE. * @rule_attr: Pointer to a rule (only of type &struct * landlock_path_beneath_attr for now). * @flags: Must be 0. @@ -332,6 +387,8 @@ static int add_rule_path_beneath(struct landlock_ruleset *const ruleset, * Possible returned errors are: * * - %EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time; + * - %EAFNOSUPPORT: @rule_type is LANDLOCK_RULE_NET_SERVICE but TCP/IP is not + * supported by the running kernel; * - %EINVAL: @flags is not 0, or inconsistent access in the rule (i.e. * &landlock_path_beneath_attr.allowed_access is not a subset of the * ruleset handled accesses); @@ -366,6 +423,9 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd, case LANDLOCK_RULE_PATH_BENEATH: err = add_rule_path_beneath(ruleset, rule_attr); break; + case LANDLOCK_RULE_NET_SERVICE: + err = add_rule_net_service(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 792c3f0a59b4..646f778dfb1e 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(3, landlock_create_ruleset(NULL, 0, + ASSERT_EQ(4, landlock_create_ruleset(NULL, 0, LANDLOCK_CREATE_RULESET_VERSION)); ASSERT_EQ(-1, landlock_create_ruleset(&ruleset_attr, 0, -- 2.25.1.
