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Diffstat (limited to 'security/landlock/log.c')
| -rw-r--r-- | security/landlock/log.c | 587 |
1 files changed, 587 insertions, 0 deletions
diff --git a/security/landlock/log.c b/security/landlock/log.c new file mode 100644 index 000000000..a8578a6f2 --- /dev/null +++ b/security/landlock/log.c @@ -0,0 +1,587 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Landlock - Log helpers + * + * Copyright © 2023-2025 Microsoft Corporation + * Copyright © 2026 Cloudflare, Inc. + */ + +#include <kunit/test.h> +#include <linux/bitops.h> +#include <uapi/linux/landlock.h> + +#include "access.h" +#include "audit.h" +#include "common.h" +#include "cred.h" +#include "domain.h" +#include "limits.h" +#include "log.h" +#include "ruleset.h" +#include "trace.h" + +static struct landlock_hierarchy * +get_hierarchy(const struct landlock_domain *const domain, const size_t layer) +{ + struct landlock_hierarchy *hierarchy = domain->hierarchy; + ssize_t i; + + if (WARN_ON_ONCE(layer >= domain->num_layers)) + return hierarchy; + + for (i = domain->num_layers - 1; i > layer; i--) { + if (WARN_ON_ONCE(!hierarchy->parent)) + break; + + hierarchy = hierarchy->parent; + } + + return hierarchy; +} + +#ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST + +static void test_get_hierarchy(struct kunit *const test) +{ + struct landlock_hierarchy dom0_hierarchy = { + .id = 10, + }; + struct landlock_hierarchy dom1_hierarchy = { + .parent = &dom0_hierarchy, + .id = 20, + }; + struct landlock_hierarchy dom2_hierarchy = { + .parent = &dom1_hierarchy, + .id = 30, + }; + struct landlock_domain dom2 = { + .hierarchy = &dom2_hierarchy, + .num_layers = 3, + }; + + KUNIT_EXPECT_EQ(test, 10, get_hierarchy(&dom2, 0)->id); + KUNIT_EXPECT_EQ(test, 20, get_hierarchy(&dom2, 1)->id); + KUNIT_EXPECT_EQ(test, 30, get_hierarchy(&dom2, 2)->id); + /* KUNIT_EXPECT_EQ(test, 30, get_hierarchy(&dom2, -1)->id); */ +} + +#endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */ + +/* Get the youngest layer that denied the access_request. */ +static size_t get_denied_layer(const struct landlock_domain *const domain, + access_mask_t *const access_request, + const struct layer_masks *masks) +{ + for (ssize_t i = ARRAY_SIZE(masks->layers) - 1; i >= 0; i--) { + if (masks->layers[i].access & *access_request) { + *access_request &= masks->layers[i].access; + return i; + } + } + + /* Not found - fall back to default values */ + *access_request = 0; + return domain->num_layers - 1; +} + +#ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST + +static void test_get_denied_layer(struct kunit *const test) +{ + const struct landlock_domain dom = { + .num_layers = 5, + }; + const struct layer_masks masks = { + .layers[0].access = LANDLOCK_ACCESS_FS_EXECUTE | + LANDLOCK_ACCESS_FS_READ_DIR, + .layers[1].access = LANDLOCK_ACCESS_FS_READ_FILE | + LANDLOCK_ACCESS_FS_READ_DIR, + .layers[2].access = LANDLOCK_ACCESS_FS_REMOVE_DIR, + }; + access_mask_t access; + + access = LANDLOCK_ACCESS_FS_EXECUTE; + KUNIT_EXPECT_EQ(test, 0, get_denied_layer(&dom, &access, &masks)); + KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_EXECUTE); + + access = LANDLOCK_ACCESS_FS_READ_FILE; + KUNIT_EXPECT_EQ(test, 1, get_denied_layer(&dom, &access, &masks)); + KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_READ_FILE); + + access = LANDLOCK_ACCESS_FS_READ_DIR; + KUNIT_EXPECT_EQ(test, 1, get_denied_layer(&dom, &access, &masks)); + KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_READ_DIR); + + access = LANDLOCK_ACCESS_FS_READ_FILE | LANDLOCK_ACCESS_FS_READ_DIR; + KUNIT_EXPECT_EQ(test, 1, get_denied_layer(&dom, &access, &masks)); + KUNIT_EXPECT_EQ(test, access, + LANDLOCK_ACCESS_FS_READ_FILE | + LANDLOCK_ACCESS_FS_READ_DIR); + + access = LANDLOCK_ACCESS_FS_EXECUTE | LANDLOCK_ACCESS_FS_READ_DIR; + KUNIT_EXPECT_EQ(test, 1, get_denied_layer(&dom, &access, &masks)); + KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_READ_DIR); + + access = LANDLOCK_ACCESS_FS_WRITE_FILE; + KUNIT_EXPECT_EQ(test, 4, get_denied_layer(&dom, &access, &masks)); + KUNIT_EXPECT_EQ(test, access, 0); +} + +#endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */ + +static size_t +get_layer_from_deny_masks(access_mask_t *const access_request, + const access_mask_t all_existing_optional_access, + const deny_masks_t deny_masks, + optional_access_t quiet_optional_accesses, + bool *quiet) +{ + const unsigned long access_opt = all_existing_optional_access; + const unsigned long access_req = *access_request; + access_mask_t missing = 0; + size_t youngest_layer = 0; + size_t access_index = 0; + unsigned long access_bit; + bool should_quiet = false; + + /* This will require change with new object types. */ + WARN_ON_ONCE(access_opt != _LANDLOCK_ACCESS_FS_OPTIONAL); + + for_each_set_bit(access_bit, &access_opt, + BITS_PER_TYPE(access_mask_t)) { + if (access_req & BIT(access_bit)) { + const size_t layer = + (deny_masks >> + (access_index * + HWEIGHT(LANDLOCK_MAX_NUM_LAYERS - 1))) & + (LANDLOCK_MAX_NUM_LAYERS - 1); + const bool layer_has_quiet = + !!(quiet_optional_accesses & BIT(access_index)); + + if (layer > youngest_layer) { + youngest_layer = layer; + missing = BIT(access_bit); + should_quiet = layer_has_quiet; + } else if (layer == youngest_layer) { + missing |= BIT(access_bit); + /* + * Whether the layer has rules with quiet flag + * covering the file accessed does not depend on + * the access, and so the following + * WARN_ON_ONCE() should not fail. + */ + WARN_ON_ONCE(should_quiet && !layer_has_quiet); + should_quiet = layer_has_quiet; + } + } + access_index++; + } + + *access_request = missing; + *quiet = should_quiet; + return youngest_layer; +} + +#ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST + +static void test_get_layer_from_deny_masks(struct kunit *const test) +{ + deny_masks_t deny_mask; + access_mask_t access; + optional_access_t quiet_optional_accesses; + bool quiet; + + /* truncate:0 ioctl_dev:2 */ + deny_mask = 0x20; + quiet_optional_accesses = 0; + + access = LANDLOCK_ACCESS_FS_TRUNCATE; + KUNIT_EXPECT_EQ(test, 0, + get_layer_from_deny_masks( + &access, _LANDLOCK_ACCESS_FS_OPTIONAL, + deny_mask, quiet_optional_accesses, &quiet)); + KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_TRUNCATE); + KUNIT_EXPECT_EQ(test, quiet, false); + + access = LANDLOCK_ACCESS_FS_IOCTL_DEV; + KUNIT_EXPECT_EQ(test, 2, + get_layer_from_deny_masks( + &access, _LANDLOCK_ACCESS_FS_OPTIONAL, + deny_mask, quiet_optional_accesses, &quiet)); + KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_IOCTL_DEV); + KUNIT_EXPECT_EQ(test, quiet, false); + + access = LANDLOCK_ACCESS_FS_TRUNCATE | LANDLOCK_ACCESS_FS_IOCTL_DEV; + KUNIT_EXPECT_EQ(test, 2, + get_layer_from_deny_masks( + &access, _LANDLOCK_ACCESS_FS_OPTIONAL, + deny_mask, quiet_optional_accesses, &quiet)); + KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_IOCTL_DEV); + KUNIT_EXPECT_EQ(test, quiet, false); + + /* layer denying truncate: quiet, ioctl: not quiet */ + quiet_optional_accesses = 0b01; + + access = LANDLOCK_ACCESS_FS_TRUNCATE; + KUNIT_EXPECT_EQ(test, 0, + get_layer_from_deny_masks( + &access, _LANDLOCK_ACCESS_FS_OPTIONAL, + deny_mask, quiet_optional_accesses, &quiet)); + KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_TRUNCATE); + KUNIT_EXPECT_EQ(test, quiet, true); + + access = LANDLOCK_ACCESS_FS_IOCTL_DEV; + KUNIT_EXPECT_EQ(test, 2, + get_layer_from_deny_masks( + &access, _LANDLOCK_ACCESS_FS_OPTIONAL, + deny_mask, quiet_optional_accesses, &quiet)); + KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_IOCTL_DEV); + KUNIT_EXPECT_EQ(test, quiet, false); + + access = LANDLOCK_ACCESS_FS_TRUNCATE | LANDLOCK_ACCESS_FS_IOCTL_DEV; + KUNIT_EXPECT_EQ(test, 2, + get_layer_from_deny_masks( + &access, _LANDLOCK_ACCESS_FS_OPTIONAL, + deny_mask, quiet_optional_accesses, &quiet)); + KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_IOCTL_DEV); + KUNIT_EXPECT_EQ(test, quiet, false); + + /* Reverse order - truncate:2 ioctl_dev:0 */ + deny_mask = 0x02; + quiet_optional_accesses = 0; + + access = LANDLOCK_ACCESS_FS_TRUNCATE; + KUNIT_EXPECT_EQ(test, 2, + get_layer_from_deny_masks( + &access, _LANDLOCK_ACCESS_FS_OPTIONAL, + deny_mask, quiet_optional_accesses, &quiet)); + KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_TRUNCATE); + KUNIT_EXPECT_EQ(test, quiet, false); + + access = LANDLOCK_ACCESS_FS_IOCTL_DEV; + KUNIT_EXPECT_EQ(test, 0, + get_layer_from_deny_masks( + &access, _LANDLOCK_ACCESS_FS_OPTIONAL, + deny_mask, quiet_optional_accesses, &quiet)); + KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_IOCTL_DEV); + KUNIT_EXPECT_EQ(test, quiet, false); + + access = LANDLOCK_ACCESS_FS_TRUNCATE | LANDLOCK_ACCESS_FS_IOCTL_DEV; + KUNIT_EXPECT_EQ(test, 2, + get_layer_from_deny_masks( + &access, _LANDLOCK_ACCESS_FS_OPTIONAL, + deny_mask, quiet_optional_accesses, &quiet)); + KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_TRUNCATE); + KUNIT_EXPECT_EQ(test, quiet, false); + + /* layer denying truncate: quiet, ioctl: not quiet */ + quiet_optional_accesses = 0b01; + + access = LANDLOCK_ACCESS_FS_TRUNCATE; + KUNIT_EXPECT_EQ(test, 2, + get_layer_from_deny_masks( + &access, _LANDLOCK_ACCESS_FS_OPTIONAL, + deny_mask, quiet_optional_accesses, &quiet)); + KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_TRUNCATE); + KUNIT_EXPECT_EQ(test, quiet, true); + + access = LANDLOCK_ACCESS_FS_IOCTL_DEV; + KUNIT_EXPECT_EQ(test, 0, + get_layer_from_deny_masks( + &access, _LANDLOCK_ACCESS_FS_OPTIONAL, + deny_mask, quiet_optional_accesses, &quiet)); + KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_IOCTL_DEV); + KUNIT_EXPECT_EQ(test, quiet, false); + + access = LANDLOCK_ACCESS_FS_TRUNCATE | LANDLOCK_ACCESS_FS_IOCTL_DEV; + KUNIT_EXPECT_EQ(test, 2, + get_layer_from_deny_masks( + &access, _LANDLOCK_ACCESS_FS_OPTIONAL, + deny_mask, quiet_optional_accesses, &quiet)); + KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_TRUNCATE); + KUNIT_EXPECT_EQ(test, quiet, true); + + /* layer denying truncate: not quiet, ioctl: quiet */ + quiet_optional_accesses = 0b10; + + access = LANDLOCK_ACCESS_FS_TRUNCATE; + KUNIT_EXPECT_EQ(test, 2, + get_layer_from_deny_masks( + &access, _LANDLOCK_ACCESS_FS_OPTIONAL, + deny_mask, quiet_optional_accesses, &quiet)); + KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_TRUNCATE); + KUNIT_EXPECT_EQ(test, quiet, false); + + access = LANDLOCK_ACCESS_FS_IOCTL_DEV; + KUNIT_EXPECT_EQ(test, 0, + get_layer_from_deny_masks( + &access, _LANDLOCK_ACCESS_FS_OPTIONAL, + deny_mask, quiet_optional_accesses, &quiet)); + KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_IOCTL_DEV); + KUNIT_EXPECT_EQ(test, quiet, true); + + access = LANDLOCK_ACCESS_FS_TRUNCATE | LANDLOCK_ACCESS_FS_IOCTL_DEV; + KUNIT_EXPECT_EQ(test, 2, + get_layer_from_deny_masks( + &access, _LANDLOCK_ACCESS_FS_OPTIONAL, + deny_mask, quiet_optional_accesses, &quiet)); + KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_TRUNCATE); + KUNIT_EXPECT_EQ(test, quiet, false); + + /* truncate:15 ioctl_dev:15 */ + deny_mask = 0xff; + quiet_optional_accesses = 0; + + access = LANDLOCK_ACCESS_FS_TRUNCATE; + KUNIT_EXPECT_EQ(test, 15, + get_layer_from_deny_masks( + &access, _LANDLOCK_ACCESS_FS_OPTIONAL, + deny_mask, quiet_optional_accesses, &quiet)); + KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_TRUNCATE); + KUNIT_EXPECT_EQ(test, quiet, false); + + access = LANDLOCK_ACCESS_FS_TRUNCATE | LANDLOCK_ACCESS_FS_IOCTL_DEV; + KUNIT_EXPECT_EQ(test, 15, + get_layer_from_deny_masks( + &access, _LANDLOCK_ACCESS_FS_OPTIONAL, + deny_mask, quiet_optional_accesses, &quiet)); + KUNIT_EXPECT_EQ(test, access, + LANDLOCK_ACCESS_FS_TRUNCATE | + LANDLOCK_ACCESS_FS_IOCTL_DEV); + KUNIT_EXPECT_EQ(test, quiet, false); + + /* Both quiet (same layer so quietness must be the same) */ + quiet_optional_accesses = 0b11; + + access = LANDLOCK_ACCESS_FS_TRUNCATE; + KUNIT_EXPECT_EQ(test, 15, + get_layer_from_deny_masks( + &access, _LANDLOCK_ACCESS_FS_OPTIONAL, + deny_mask, quiet_optional_accesses, &quiet)); + KUNIT_EXPECT_EQ(test, access, LANDLOCK_ACCESS_FS_TRUNCATE); + KUNIT_EXPECT_EQ(test, quiet, true); + + access = LANDLOCK_ACCESS_FS_TRUNCATE | LANDLOCK_ACCESS_FS_IOCTL_DEV; + KUNIT_EXPECT_EQ(test, 15, + get_layer_from_deny_masks( + &access, _LANDLOCK_ACCESS_FS_OPTIONAL, + deny_mask, quiet_optional_accesses, &quiet)); + KUNIT_EXPECT_EQ(test, access, + LANDLOCK_ACCESS_FS_TRUNCATE | + LANDLOCK_ACCESS_FS_IOCTL_DEV); + KUNIT_EXPECT_EQ(test, quiet, true); +} + +#endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */ + +static bool is_valid_request(const struct landlock_request *const request) +{ + if (WARN_ON_ONCE(request->layer_plus_one > LANDLOCK_MAX_NUM_LAYERS)) + return false; + + if (WARN_ON_ONCE(!(!!request->layer_plus_one ^ !!request->access))) + return false; + + if (request->access) { + if (WARN_ON_ONCE(!(!!request->layer_masks ^ + !!request->all_existing_optional_access))) + return false; + } else { + if (WARN_ON_ONCE(request->layer_masks || + request->all_existing_optional_access)) + return false; + } + + if (request->deny_masks) { + if (WARN_ON_ONCE(!request->all_existing_optional_access)) + return false; + static_assert(sizeof(request->all_existing_optional_access) == + sizeof(u32)); + if (WARN_ON_ONCE( + request->quiet_optional_accesses >= + BIT(hweight32( + request->all_existing_optional_access)))) + return false; + } + + return true; +} + +static access_mask_t +pick_access_mask_for_request_type(const enum landlock_request_type type, + const struct access_masks access_masks) +{ + switch (type) { + case LANDLOCK_REQUEST_FS_ACCESS: + return access_masks.fs; + case LANDLOCK_REQUEST_NET_ACCESS: + return access_masks.net; + default: + WARN_ONCE(1, "Invalid request type %d passed to %s", type, + __func__); + return 0; + } +} + +/* + * Whether a quiet rule silences the denial: the rule must cover the whole + * denied access in the layer that denied it (a quiet rule in a non-denying + * layer does not suppress the denial). + */ +static bool +is_denial_quieted(const struct landlock_request *const request, + const struct landlock_hierarchy *const youngest_denied, + const access_mask_t missing, const bool object_quiet_flag) +{ + if (object_quiet_flag) { + const access_mask_t quiet_mask = + pick_access_mask_for_request_type( + request->type, youngest_denied->quiet_masks); + + return (quiet_mask & missing) == missing; + } + + /* + * Either the object is not quiet, or this is a scope request. We check + * request->type to distinguish between the two cases. + */ + switch (request->type) { + case LANDLOCK_REQUEST_SCOPE_SIGNAL: + return !!(youngest_denied->quiet_masks.scope & + LANDLOCK_SCOPE_SIGNAL); + case LANDLOCK_REQUEST_SCOPE_ABSTRACT_UNIX_SOCKET: + return !!(youngest_denied->quiet_masks.scope & + LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET); + /* + * Leave LANDLOCK_REQUEST_PTRACE and LANDLOCK_REQUEST_FS_CHANGE_TOPOLOGY + * unhandled for now - they are never quiet. + */ + default: + return false; + } +} + +/* + * Computes whether a denial from youngest_denied is selected for logging by the + * domain's policy: its logging must not be disabled (by both per-execution + * flags being off, or by an ancestor's + * LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF), the per-execution flag matching + * same_exec must be set, and no quiet rule may cover the denied access. + * landlock_log_denial() computes this once and passes it to + * landlock_audit_denial(), which additionally requires audit_enabled. + */ +static bool +is_denial_logged(const struct landlock_request *const request, + const struct landlock_hierarchy *const youngest_denied, + const access_mask_t missing, const bool same_exec, + const bool object_quiet_flag) +{ + if (READ_ONCE(youngest_denied->log_status) == LANDLOCK_LOG_DISABLED) + return false; + + if (!(same_exec ? youngest_denied->log_same_exec : + youngest_denied->log_new_exec)) + return false; + + return !is_denial_quieted(request, youngest_denied, missing, + object_quiet_flag); +} + +/** + * landlock_log_denial - Log a denied access + * + * @subject: The Landlock subject's credential denying an action. + * @request: Detail of the user space request. + */ +void landlock_log_denial(const struct landlock_cred_security *const subject, + const struct landlock_request *const request) +{ + struct landlock_hierarchy *youngest_denied; + size_t youngest_layer; + access_mask_t missing; + bool object_quiet_flag = false; + + if (WARN_ON_ONCE(!subject || !subject->domain || + !subject->domain->hierarchy || !request)) + return; + + if (!is_valid_request(request)) + return; + + missing = request->access; + if (missing) { + /* Gets the nearest domain that denies the request. */ + if (request->layer_masks) { + youngest_layer = get_denied_layer(subject->domain, + &missing, + request->layer_masks); + object_quiet_flag = + request->layer_masks->layers[youngest_layer] + .quiet; + } else { + youngest_layer = get_layer_from_deny_masks( + &missing, _LANDLOCK_ACCESS_FS_OPTIONAL, + request->deny_masks, + request->quiet_optional_accesses, + &object_quiet_flag); + } + youngest_denied = + get_hierarchy(subject->domain, youngest_layer); + } else { + youngest_layer = request->layer_plus_one - 1; + youngest_denied = + get_hierarchy(subject->domain, youngest_layer); + } + + const bool same_exec = !!(subject->domain_exec & BIT(youngest_layer)); + const bool logged = is_denial_logged(request, youngest_denied, missing, + same_exec, object_quiet_flag); + + /* + * Consistently keeps track of the number of denied access requests even + * if audit is currently disabled, or if audit rules currently exclude + * this record type, or if landlock_restrict_self(2)'s flags quiet logs. + */ + atomic64_inc(&youngest_denied->num_denials); + + landlock_trace_denial(request, youngest_denied, missing, same_exec, + logged); + landlock_audit_denial(request, youngest_denied, missing, logged); +} + +/** + * landlock_log_free_domain - Log domain deallocation + * + * @hierarchy: The domain's hierarchy being deallocated. + * + * Called from landlock_put_domain_deferred() (via a work queue scheduled by + * hook_cred_free()) or directly from landlock_put_domain(). + */ +void landlock_log_free_domain(const struct landlock_hierarchy *const hierarchy) +{ + if (WARN_ON_ONCE(!hierarchy)) + return; + + landlock_trace_free_domain(hierarchy); + landlock_audit_free_domain(hierarchy); +} + +#ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST + +static struct kunit_case test_cases[] = { + /* clang-format off */ + KUNIT_CASE(test_get_hierarchy), + KUNIT_CASE(test_get_denied_layer), + KUNIT_CASE(test_get_layer_from_deny_masks), + {} + /* clang-format on */ +}; + +static struct kunit_suite test_suite = { + .name = "landlock_log", + .test_cases = test_cases, +}; + +kunit_test_suite(test_suite); + +#endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */ |