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Message-ID: <57f150b2-0920-8567-8351-1bdb74684cfa@huawei.com> Date: Fri, 20 Oct 2023 07:08:33 +0300 From: "Konstantin Meskhidze (A)" <konstantin.meskhidze@...wei.com> To: Mickaël Salaün <mic@...ikod.net> CC: <willemdebruijn.kernel@...il.com>, <gnoack3000@...il.com>, <linux-security-module@...r.kernel.org>, <netdev@...r.kernel.org>, <netfilter-devel@...r.kernel.org>, <yusongping@...wei.com>, <artem.kuzin@...wei.com> Subject: Re: [PATCH v13 08/12] landlock: Add network rules and TCP hooks support 10/18/2023 3:29 PM, Mickaël Salaün пишет: > On Mon, Oct 16, 2023 at 09:50:26AM +0800, Konstantin Meskhidze wrote: >> This commit adds network rules support in the ruleset management > > Here are some advices to better write commit messages: > https://docs.kernel.org/process/submitting-patches.html#describe-your-changes > The "Describe your changes in imperative mood" part is important for > this commit and others. Most of this patch series' commit messages need > small updates. Ok. I will refactor commit messages with "imperative mood". Thanks. > >> 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 > > Please explain the "why" (when it makes sense) instead of just listing > the "what". Ok. > >> rights can be stored. Implement socket_bind() and socket_connect() >> LSM hooks, which enables to restrict TCP socket binding and connection >> to specific ports. > > I reworded and moved this part in last: >> For the file system, a file descriptor is a direct access to a file/data. >> But for the network, it's impossible to identify for which data/peer a >> newly created socket will give access to, it's needed to wait for a >> connect or bind request to identify the use case for this socket. >> That's why the access rights (related to ports) are tied to an opened >> socket, but this would not align with the way Landlock access control >> works for the filesystem [2]. Thanks. > > Please add empty line to split paragraphs. Got it. > >> The new landlock_net_port_attr structure has two fields. The allowed_access >> field contains the LANDLOCK_ACCESS_NET_* rights. The port field contains >> the port value according to the allowed protocol. This field can >> take up to a 64-bit value [1] but the maximum value depends on the related >> protocol (e.g. 16-bit for TCP). > > For the file system, a file descriptor is a direct access to a file/data. > However, for network sockets, we cannot identify for which data or peer a newly > created socket will give access to. Indeed, we need to wait for a connect or > bind request to identify the use case for this socket. > > Access rights are not tied to socket file descriptors. Instead, bind and > connect actions are controlled by the task's domain. As for the filesystem, a > directory file descriptor may enable to open another file (i.e. a new data > item), but this opening is restricted by the task's domain, not the file > descriptor's access rights [2]. > >> >> [1] >> https://lore.kernel.org/r/278ab07f-7583-a4e0-3d37-1bacd091531d@digikod.net >> [2] >> https://lore.kernel.org/all/263c1eb3-602f-57fe-8450-3f138581bee7@digikod.net > > [1] https://lore.kernel.org/r/278ab07f-7583-a4e0-3d37-1bacd091531d@digikod.net > [2] https://lore.kernel.org/r/263c1eb3-602f-57fe-8450-3f138581bee7@digikod.net > Thanks. > >> >> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@...wei.com> >> Link: https://lore.kernel.org/r/20230920092641.832134-9-konstantin.meskhidze@huawei.com >> [mic: Remove !ARCH_EPHEMERAL_INODES in Kconfig, and add landlock_ prefix >> to add_rule_net_service()] >> Signed-off-by: Mickaël Salaün <mic@...ikod.net> >> --- >> >> Changes since v12: >> * Moves add_rule_net_port() back in syscalls.c and makes it static. >> * Deletes bind_access_mask allowing bind action rule on port 0. >> * Adds comment about port 0 in landlock_net_port_attr structure. >> * Removes !ARCH_EPHEMERAL_INODES from Kconfig. >> * Minor fixes. >> * Refactors commit message. >> >> Changes since v11: >> * Replaces dates with "2022-2023" in net.c/h files headers. >> * Removes WARN_ON_ONCE(!domain) in check_socket_access(). >> * Using "typeof(*address)" instead of offsetofend(struct sockaddr, sa_family). >> * Renames LANDLOCK_RULE_NET_SERVICE to LANDLOCK_RULE_NET_PORT. >> * Renames landlock_net_service_attr to landlock_net_port_attr. >> * Defines two add_rule_net_service() functions according to >> IS_ENABLED(CONFIG_INET) instead of changing the body of the only >> function. >> * Adds af_family consistency check while handling AF_UNSPEC specifically. >> * Adds bind_access_mask in add_rule_net_service() to deny all rules with bind >> action on port zero. >> * Minor fixes. >> * Refactors commit message. >> >> Changes since v10: >> * Removes "packed" attribute. >> * Applies Mickaёl's patch with some refactoring. >> * Deletes get_port() and check_addrlen() helpers. >> * Refactors check_socket_access() by squashing get_port() and >> check_addrlen() helpers into it. >> * Fixes commit message. >> >> 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 | 56 ++++++ >> security/landlock/Kconfig | 1 + >> security/landlock/Makefile | 2 + >> security/landlock/limits.h | 5 + >> security/landlock/net.c | 198 +++++++++++++++++++ >> security/landlock/net.h | 33 ++++ >> security/landlock/ruleset.c | 62 +++++- >> security/landlock/ruleset.h | 59 +++++- >> security/landlock/setup.c | 2 + >> security/landlock/syscalls.c | 69 ++++++- >> tools/testing/selftests/landlock/base_test.c | 2 +- >> 11 files changed, 466 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..25349666b19e 100644 >> --- a/include/uapi/linux/landlock.h >> +++ b/include/uapi/linux/landlock.h >> @@ -31,6 +31,12 @@ 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 +60,11 @@ enum landlock_rule_type { >> * landlock_path_beneath_attr . >> */ >> LANDLOCK_RULE_PATH_BENEATH = 1, >> + /** >> + * @LANDLOCK_RULE_NET_PORT: Type of a &struct >> + * landlock_net_port_attr . >> + */ >> + LANDLOCK_RULE_NET_PORT = 2, > > We don't need the explicit " = 2". Fixed. Thanks. > >> }; >> >> /** >> @@ -79,6 +90,32 @@ struct landlock_path_beneath_attr { >> */ >> } __attribute__((packed)); >> >> +/** >> + * struct landlock_net_port_attr - Network port definition >> + * >> + * Argument of sys_landlock_add_rule(). >> + */ >> +struct landlock_net_port_attr { >> + /** >> + * @allowed_access: Bitmask of allowed access network for a port >> + * (cf. `Network flags`_). >> + */ >> + __u64 allowed_access; >> + /** >> + * @port: Network port. Landlock does not forbid rules with port 0, >> + * since some network services use it. Port 0 is a reserved one in >> + * TCP/IP networking, meaning that it should not be used in TCP or >> + * UDP messages. To allocate its source port number, services call >> + * TCP/IP network functions like bind() to request one. With port 0 >> + * it triggers the operating system to automatically search for >> + * and return a suitable available port in the TCP/IP dynamic >> + * port number range. This port range can be controlled by a >> + * sysadmin with /proc/sys/net/ipv4/ip_local_port_range sysctl, >> + * which is also used by IPv6. > > This looks too inspired from > https://www.lifewire.com/port-0-in-tcp-and-udp-818145 Yep. You are right. > > Let's make it simpler: > > * @port: Network port. > * > * It should be noted that port 0 passed to :manpage:`bind(2)` will > * bind to an available port from a specific port range. This can be > * configured thanks to the ``/proc/sys/net/ipv4/ip_local_port_range`` > * sysctl (also used for IPv6). A Landlock rule with port 0 and the > * ``LANDLOCK_ACCESS_NET_BIND_TCP`` right means that requesting to bind > * on port 0 is allowed and it will automatically translate to binding > * on the related port range. > Thanks. > >> + */ >> + __u64 port; >> +}; >> + >> /** >> * DOC: fs_access >> * >> @@ -189,4 +226,23 @@ 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. > > You can add: > "This is supported since ABI 4." Updated. > >> + * >> + * 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 c1e862a38410..c4bf0d5eff39 100644 >> --- a/security/landlock/Kconfig >> +++ b/security/landlock/Kconfig >> @@ -3,6 +3,7 @@ >> config SECURITY_LANDLOCK >> bool "Landlock support" >> depends on SECURITY >> + 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..93c9c6f91556 100644 >> --- a/security/landlock/limits.h >> +++ b/security/landlock/limits.h >> @@ -23,6 +23,11 @@ >> #define LANDLOCK_NUM_ACCESS_FS __const_hweight64(LANDLOCK_MASK_ACCESS_FS) >> #define LANDLOCK_SHIFT_ACCESS_FS 0 >> >> +#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..1bf26cf3c41b >> --- /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 © 2022-2023 Huawei Tech. Co., Ltd. >> + * Copyright © 2022-2023 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 = (__force uintptr_t)htons(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_socket_access(struct socket *const sock, > > To be consistent with current_check_access_path(), please rename to > current_check_access_socket(). Done. Thanks. > >> + struct sockaddr *const address, >> + const int addrlen, >> + const access_mask_t access_request) >> +{ >> + __be16 port; >> + layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {}; >> + const struct landlock_rule *rule; >> + access_mask_t handled_access; >> + struct landlock_id id = { >> + .type = LANDLOCK_KEY_NET_PORT, >> + }; >> + const struct landlock_ruleset *const domain = get_current_net_domain(); > > For consistency with other functions, s/domain/dom/g Ok. Fixed. > >> + >> + if (!domain) >> + return 0; >> + if (WARN_ON_ONCE(domain->num_layers < 1)) >> + return -EACCES; >> + >> + /* Checks if it's a (potential) TCP socket. */ >> + if (sock->type != SOCK_STREAM) >> + return 0; >> + >> + /* Checks for minimal header length to safely read sa_family. */ >> + if (addrlen < offsetofend(typeof(*address), sa_family)) >> + return -EINVAL; >> + >> + switch (address->sa_family) { >> + 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 > > #endif /* IS_ENABLED(CONFIG_INET) */ #endif /* IS_ENABLED(CONFIG_IPV6) */ I suppose. > >> + default: >> + return 0; >> + } >> + >> + /* Specific AF_UNSPEC handling. */ >> + if (address->sa_family == 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. >> + * >> + * For a TCP access control system, this request is legitimate. >> + * Let the network stack handle potential inconsistencies and >> + * return -EINVAL if needed. >> + */ >> + 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. >> + * >> + * We could return 0 and let the network stack handle these >> + * checks, but it is safer to return a proper error and test >> + * consistency thanks to kselftest. >> + */ >> + if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) { >> + /* addrlen has already been checked for AF_UNSPEC. */ >> + const struct sockaddr_in *const sockaddr = >> + (struct sockaddr_in *)address; >> + >> + if (sock->sk->__sk_common.skc_family != AF_INET) >> + return -EINVAL; >> + >> + if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY)) >> + return -EAFNOSUPPORT; >> + } >> + } else { >> + /* >> + * Checks sa_family consistency to not wrongfully return >> + * -EACCES instead of -EINVAL. Valid sa_family changes are >> + * only (from AF_INET or AF_INET6) to AF_UNSPEC. >> + * >> + * We could return 0 and let the network stack handle this >> + * check, but it is safer to return a proper error and test >> + * consistency thanks to kselftest. >> + */ >> + if (address->sa_family != sock->sk->__sk_common.skc_family) >> + return -EINVAL; >> + } >> + >> + id.key.data = (__force uintptr_t)port; >> + BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data)); >> + >> + rule = landlock_find_rule(domain, id); >> + handled_access = landlock_init_layer_masks( >> + domain, access_request, &layer_masks, LANDLOCK_KEY_NET_PORT); >> + if (landlock_unmask_layers(rule, handled_access, &layer_masks, >> + ARRAY_SIZE(layer_masks))) >> + return 0; >> + >> + return -EACCES; >> +} >> + >> +static int hook_socket_bind(struct socket *const sock, >> + struct sockaddr *const address, const int addrlen) >> +{ >> + return check_socket_access(sock, address, addrlen, >> + LANDLOCK_ACCESS_NET_BIND_TCP); >> +} >> + >> +static int hook_socket_connect(struct socket *const sock, >> + struct sockaddr *const address, >> + const int addrlen) >> +{ >> + return check_socket_access(sock, address, addrlen, >> + LANDLOCK_ACCESS_NET_CONNECT_TCP); >> +} >> + >> +static struct security_hook_list landlock_hooks[] __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..588a49fd6907 >> --- /dev/null >> +++ b/security/landlock/net.h >> @@ -0,0 +1,33 @@ >> +/* SPDX-License-Identifier: GPL-2.0-only */ >> +/* >> + * Landlock LSM - Network management and hooks >> + * >> + * Copyright © 2022-2023 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) >> +{ >> +} >> + >> +static inline int >> +landlock_append_net_rule(struct landlock_ruleset *const ruleset, const u16 port, >> + access_mask_t access_rights); >> +{ >> + return -EAFNOSUPPORT; >> +} >> +#endif /* IS_ENABLED(CONFIG_INET) */ >> + >> +#endif /* _SECURITY_LANDLOCK_NET_H */ >> diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c >> index 4c209acee01e..1fe4298ff4a7 100644 >> --- a/security/landlock/ruleset.c >> +++ b/security/landlock/ruleset.c >> @@ -36,6 +36,11 @@ 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 +51,21 @@ 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); > > This is good, but it is not tested: we need to add a test that both > handle FS and net restrictions. You can add one in net.c, just handling > LANDLOCK_ACCESS_FS_READ_DIR and LANDLOCK_ACCESS_NET_BIND_TCP, add one > rule with path_beneath (e.g. /dev) and another with net_port, and check > that open("/") is denied, open("/dev") is allowed, and and only the > allowed port is allowed with bind(). This test should be simple and can > only check against an IPv4 socket, i.e. using ipv4_tcp fixture, just > after port_endianness. fcntl.h should then be included by net.c Ok. > > I guess that was the purpose of layout1.with_net (in fs_test.c) but it Yep. I added this kind of nest in fs_test.c to test both fs and network rules together. > is not complete. You can revamp this test and move it to net.c > following the above suggestions, keeping it consistent with other tests > in net.c . You don't need the test_open() nor create_ruleset() helpers. > > This test must failed if we change "ruleset->access_masks[layer_level] |=" > to "ruleset->access_masks[layer_level] =" in > landlock_add_fs_access_mask() or landlock_add_net_access_mask(). Do you want to change it? Why? Fs and network masks are ORed to not intersect with each other. > >> return new_ruleset; >> } >> >> @@ -74,6 +84,11 @@ static bool is_object_pointer(const enum landlock_key_type 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) */ >> + >> default: >> WARN_ON_ONCE(1); >> return false; >> @@ -126,7 +141,13 @@ static struct rb_root *get_root(struct landlock_ruleset *const ruleset, >> case LANDLOCK_KEY_INODE: >> return &ruleset->root_inode; >> >> +#if IS_ENABLED(CONFIG_INET) >> + case LANDLOCK_KEY_NET_PORT: >> + return &ruleset->root_net_port; >> +#endif /* IS_ENABLED(CONFIG_INET) */ >> + >> default: >> + WARN_ON_ONCE(1); > > Please move this WARN to the patch that added the previous and next > lines. OK. Will be moved. > >> return ERR_PTR(-EINVAL); >> } >> } >> @@ -153,7 +174,8 @@ 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))); >> } >> >> /** >> @@ -370,6 +392,13 @@ 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); >> @@ -426,6 +455,13 @@ 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; >> @@ -455,6 +491,13 @@ 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); >> } >> @@ -635,7 +678,8 @@ 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 > > "%LANDLOCK_NUM_ACCESS_FS or %LANDLOCK_NUM_ACCESS_NET" Done. > >> + * 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 >> @@ -656,6 +700,14 @@ 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 1ede2b9a79b7..ba4a06035599 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 +87,11 @@ enum landlock_key_type { >> * keys. >> */ >> LANDLOCK_KEY_INODE = 1, >> + /** >> + * @LANDLOCK_KEY_NET_PORT: Type of &landlock_ruleset.root_net_port's >> + * node keys. >> + */ >> + LANDLOCK_KEY_NET_PORT, >> }; >> >> /** >> @@ -158,6 +166,13 @@ struct landlock_ruleset { >> * reaches zero. >> */ >> struct rb_root root_inode; > > #if IS_ENABLED(CONFIG_INET) > OK. Done. >> + /** >> + * @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) */ Done. > >> /** >> * @hierarchy: Enables hierarchy identification even when a parent >> * domain vanishes. This is needed for the ptrace protection. >> @@ -196,13 +211,13 @@ 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 +228,8 @@ 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 +265,19 @@ 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 +295,16 @@ 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 0f6113528fa4..df81612811bf 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 __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..3ad652d9a146 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_port_attr net_port_attr; >> + size_t ruleset_size, path_beneath_size, net_port_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_port_size = sizeof(net_port_attr.allowed_access); >> + 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); >> } >> >> /* 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); >> >> @@ -282,7 +296,7 @@ static int add_rule_path_beneath(struct landlock_ruleset *const ruleset, >> int res, err; >> access_mask_t mask; >> >> - /* Copies raw user space buffer, only one type for now. */ >> + /* Copies raw user space buffer. */ > > Shouldn't this be part of a previous patch? I did it according Gunter's suggestion https://lore.kernel.org/netdev/20230627.82cde73b1efe@gnoack.org/ > >> res = copy_from_user(&path_beneath_attr, rule_attr, >> sizeof(path_beneath_attr)); >> if (res) >> @@ -315,13 +329,49 @@ static int add_rule_path_beneath(struct landlock_ruleset *const ruleset, >> return err; >> } >> >> +static int add_rule_net_port(struct landlock_ruleset *ruleset, >> + const void __user *const rule_attr) >> +{ >> + struct landlock_net_port_attr net_port_attr; >> + int res; >> + access_mask_t mask; >> + >> + /* Copies raw user space buffer. */ >> + res = copy_from_user(&net_port_attr, rule_attr, sizeof(net_port_attr)); >> + if (res) >> + return -EFAULT; >> + >> + /* >> + * Informs about useless rule: empty allowed_access (i.e. deny rules) >> + * are ignored by network actions. >> + */ >> + if (!net_port_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_port_attr.allowed_access | mask) != mask) >> + return -EINVAL; >> + >> + /* Denies inserting a rule with port higher than 65535. */ > > For consistency with the following comment: > "Denies inserting a rule with port greater than 65535." > Done. Thanks. > >> + if (net_port_attr.port > U16_MAX) >> + return -EINVAL; >> + >> + /* Imports the new rule. */ >> + return landlock_append_net_rule(ruleset, net_port_attr.port, >> + net_port_attr.allowed_access); >> +} >> + >> /** >> * 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_PORT. >> * @rule_attr: Pointer to a rule (only of type &struct >> * landlock_path_beneath_attr for now). >> * @flags: Must be 0. >> @@ -332,6 +382,8 @@ 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_PORT but TCP/IP is not > > %LANDLOCK_RULE_NET_PORT Done. > >> + * 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 > > &landlock_path_beneath_attr.allowed_access or > &landlock_net_port_attr.allowed_access is not a subset of the Fixed. Thanks. > >> * ruleset handled accesses); > > EINVAL description needs to be updated, especially for port > U16_MAX: > - * ruleset handled accesses); > + * ruleset handled accesses), or &landlock_net_port_attr.port is > + greater than 65535; Done. Thanks. > > >> @@ -366,6 +418,9 @@ 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_PORT: >> + err = add_rule_net_port(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 >> > .
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