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-rw-r--r--security/lsm_init.c543
1 files changed, 543 insertions, 0 deletions
diff --git a/security/lsm_init.c b/security/lsm_init.c
new file mode 100644
index 000000000000..124213b906af
--- /dev/null
+++ b/security/lsm_init.c
@@ -0,0 +1,543 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * LSM initialization functions
+ */
+
+#define pr_fmt(fmt) "LSM: " fmt
+
+#include <linux/init.h>
+#include <linux/lsm_hooks.h>
+
+#include "lsm.h"
+
+char *lsm_names;
+
+/* Pointers to LSM sections defined in include/asm-generic/vmlinux.lds.h */
+extern struct lsm_info __start_lsm_info[], __end_lsm_info[];
+extern struct lsm_info __start_early_lsm_info[], __end_early_lsm_info[];
+
+/* Boot-time LSM user choice */
+static __initconst const char *const builtin_lsm_order = CONFIG_LSM;
+static __initdata const char *chosen_lsm_order;
+static __initdata const char *chosen_major_lsm;
+
+/* Ordered list of LSMs to initialize. */
+static __initdata struct lsm_info *ordered_lsms[MAX_LSM_COUNT + 1];
+static __initdata struct lsm_info *exclusive;
+
+static __initdata bool debug;
+#define init_debug(...) \
+ do { \
+ if (debug) \
+ pr_info(__VA_ARGS__); \
+ } while (0)
+
+static int lsm_append(const char *new, char **result);
+
+/* Save user chosen LSM */
+static int __init choose_major_lsm(char *str)
+{
+ chosen_major_lsm = str;
+ return 1;
+}
+__setup("security=", choose_major_lsm);
+
+/* Explicitly choose LSM initialization order. */
+static int __init choose_lsm_order(char *str)
+{
+ chosen_lsm_order = str;
+ return 1;
+}
+__setup("lsm=", choose_lsm_order);
+
+/* Enable LSM order debugging. */
+static int __init enable_debug(char *str)
+{
+ debug = true;
+ return 1;
+}
+__setup("lsm.debug", enable_debug);
+
+/* Mark an LSM's enabled flag. */
+static int lsm_enabled_true __initdata = 1;
+static int lsm_enabled_false __initdata = 0;
+static void __init set_enabled(struct lsm_info *lsm, bool enabled)
+{
+ /*
+ * When an LSM hasn't configured an enable variable, we can use
+ * a hard-coded location for storing the default enabled state.
+ */
+ if (!lsm->enabled) {
+ if (enabled)
+ lsm->enabled = &lsm_enabled_true;
+ else
+ lsm->enabled = &lsm_enabled_false;
+ } else if (lsm->enabled == &lsm_enabled_true) {
+ if (!enabled)
+ lsm->enabled = &lsm_enabled_false;
+ } else if (lsm->enabled == &lsm_enabled_false) {
+ if (enabled)
+ lsm->enabled = &lsm_enabled_true;
+ } else {
+ *lsm->enabled = enabled;
+ }
+}
+
+static inline bool is_enabled(struct lsm_info *lsm)
+{
+ if (!lsm->enabled)
+ return false;
+
+ return *lsm->enabled;
+}
+
+/* Is an LSM already listed in the ordered LSMs list? */
+static bool __init exists_ordered_lsm(struct lsm_info *lsm)
+{
+ struct lsm_info **check;
+
+ for (check = ordered_lsms; *check; check++)
+ if (*check == lsm)
+ return true;
+
+ return false;
+}
+
+/* Append an LSM to the list of ordered LSMs to initialize. */
+static int last_lsm __initdata;
+static void __init append_ordered_lsm(struct lsm_info *lsm, const char *from)
+{
+ /* Ignore duplicate selections. */
+ if (exists_ordered_lsm(lsm))
+ return;
+
+ if (WARN(last_lsm == MAX_LSM_COUNT, "%s: out of LSM static calls!?\n", from))
+ return;
+
+ /* Enable this LSM, if it is not already set. */
+ if (!lsm->enabled)
+ lsm->enabled = &lsm_enabled_true;
+ ordered_lsms[last_lsm++] = lsm;
+
+ init_debug("%s ordered: %s (%s)\n", from, lsm->name,
+ is_enabled(lsm) ? "enabled" : "disabled");
+}
+
+/* Is an LSM allowed to be initialized? */
+static bool __init lsm_allowed(struct lsm_info *lsm)
+{
+ /* Skip if the LSM is disabled. */
+ if (!is_enabled(lsm))
+ return false;
+
+ /* Not allowed if another exclusive LSM already initialized. */
+ if ((lsm->flags & LSM_FLAG_EXCLUSIVE) && exclusive) {
+ init_debug("exclusive disabled: %s\n", lsm->name);
+ return false;
+ }
+
+ return true;
+}
+
+static void __init lsm_set_blob_size(int *need, int *lbs)
+{
+ int offset;
+
+ if (*need <= 0)
+ return;
+
+ offset = ALIGN(*lbs, sizeof(void *));
+ *lbs = offset + *need;
+ *need = offset;
+}
+
+static void __init lsm_set_blob_sizes(struct lsm_blob_sizes *needed)
+{
+ if (!needed)
+ return;
+
+ lsm_set_blob_size(&needed->lbs_cred, &blob_sizes.lbs_cred);
+ lsm_set_blob_size(&needed->lbs_file, &blob_sizes.lbs_file);
+ lsm_set_blob_size(&needed->lbs_ib, &blob_sizes.lbs_ib);
+ /*
+ * The inode blob gets an rcu_head in addition to
+ * what the modules might need.
+ */
+ if (needed->lbs_inode && blob_sizes.lbs_inode == 0)
+ blob_sizes.lbs_inode = sizeof(struct rcu_head);
+ lsm_set_blob_size(&needed->lbs_inode, &blob_sizes.lbs_inode);
+ lsm_set_blob_size(&needed->lbs_ipc, &blob_sizes.lbs_ipc);
+ lsm_set_blob_size(&needed->lbs_key, &blob_sizes.lbs_key);
+ lsm_set_blob_size(&needed->lbs_msg_msg, &blob_sizes.lbs_msg_msg);
+ lsm_set_blob_size(&needed->lbs_perf_event, &blob_sizes.lbs_perf_event);
+ lsm_set_blob_size(&needed->lbs_sock, &blob_sizes.lbs_sock);
+ lsm_set_blob_size(&needed->lbs_superblock, &blob_sizes.lbs_superblock);
+ lsm_set_blob_size(&needed->lbs_task, &blob_sizes.lbs_task);
+ lsm_set_blob_size(&needed->lbs_tun_dev, &blob_sizes.lbs_tun_dev);
+ lsm_set_blob_size(&needed->lbs_xattr_count,
+ &blob_sizes.lbs_xattr_count);
+ lsm_set_blob_size(&needed->lbs_bdev, &blob_sizes.lbs_bdev);
+ lsm_set_blob_size(&needed->lbs_bpf_map, &blob_sizes.lbs_bpf_map);
+ lsm_set_blob_size(&needed->lbs_bpf_prog, &blob_sizes.lbs_bpf_prog);
+ lsm_set_blob_size(&needed->lbs_bpf_token, &blob_sizes.lbs_bpf_token);
+}
+
+/* Prepare LSM for initialization. */
+static void __init prepare_lsm(struct lsm_info *lsm)
+{
+ int enabled = lsm_allowed(lsm);
+
+ /* Record enablement (to handle any following exclusive LSMs). */
+ set_enabled(lsm, enabled);
+
+ /* If enabled, do pre-initialization work. */
+ if (enabled) {
+ if ((lsm->flags & LSM_FLAG_EXCLUSIVE) && !exclusive) {
+ exclusive = lsm;
+ init_debug("exclusive chosen: %s\n", lsm->name);
+ }
+
+ lsm_set_blob_sizes(lsm->blobs);
+ }
+}
+
+/* Initialize a given LSM, if it is enabled. */
+static void __init initialize_lsm(struct lsm_info *lsm)
+{
+ if (is_enabled(lsm)) {
+ int ret;
+
+ init_debug("initializing %s\n", lsm->name);
+ ret = lsm->init();
+ WARN(ret, "%s failed to initialize: %d\n", lsm->name, ret);
+ }
+}
+
+/*
+ * Current index to use while initializing the lsm id list.
+ */
+u32 lsm_active_cnt __ro_after_init;
+const struct lsm_id *lsm_idlist[MAX_LSM_COUNT];
+
+/* Populate ordered LSMs list from comma-separated LSM name list. */
+static void __init ordered_lsm_parse(const char *order, const char *origin)
+{
+ struct lsm_info *lsm;
+ char *sep, *name, *next;
+
+ /* LSM_ORDER_FIRST is always first. */
+ for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) {
+ if (lsm->order == LSM_ORDER_FIRST)
+ append_ordered_lsm(lsm, " first");
+ }
+
+ /* Process "security=", if given. */
+ if (chosen_major_lsm) {
+ struct lsm_info *major;
+
+ /*
+ * To match the original "security=" behavior, this
+ * explicitly does NOT fallback to another Legacy Major
+ * if the selected one was separately disabled: disable
+ * all non-matching Legacy Major LSMs.
+ */
+ for (major = __start_lsm_info; major < __end_lsm_info;
+ major++) {
+ if ((major->flags & LSM_FLAG_LEGACY_MAJOR) &&
+ strcmp(major->name, chosen_major_lsm) != 0) {
+ set_enabled(major, false);
+ init_debug("security=%s disabled: %s (only one legacy major LSM)\n",
+ chosen_major_lsm, major->name);
+ }
+ }
+ }
+
+ sep = kstrdup(order, GFP_KERNEL);
+ next = sep;
+ /* Walk the list, looking for matching LSMs. */
+ while ((name = strsep(&next, ",")) != NULL) {
+ bool found = false;
+
+ for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) {
+ if (strcmp(lsm->name, name) == 0) {
+ if (lsm->order == LSM_ORDER_MUTABLE)
+ append_ordered_lsm(lsm, origin);
+ found = true;
+ }
+ }
+
+ if (!found)
+ init_debug("%s ignored: %s (not built into kernel)\n",
+ origin, name);
+ }
+
+ /* Process "security=", if given. */
+ if (chosen_major_lsm) {
+ for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) {
+ if (exists_ordered_lsm(lsm))
+ continue;
+ if (strcmp(lsm->name, chosen_major_lsm) == 0)
+ append_ordered_lsm(lsm, "security=");
+ }
+ }
+
+ /* LSM_ORDER_LAST is always last. */
+ for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) {
+ if (lsm->order == LSM_ORDER_LAST)
+ append_ordered_lsm(lsm, " last");
+ }
+
+ /* Disable all LSMs not in the ordered list. */
+ for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) {
+ if (exists_ordered_lsm(lsm))
+ continue;
+ set_enabled(lsm, false);
+ init_debug("%s skipped: %s (not in requested order)\n",
+ origin, lsm->name);
+ }
+
+ kfree(sep);
+}
+
+static void __init report_lsm_order(void)
+{
+ struct lsm_info **lsm, *early;
+ int first = 0;
+
+ pr_info("initializing lsm=");
+
+ /* Report each enabled LSM name, comma separated. */
+ for (early = __start_early_lsm_info;
+ early < __end_early_lsm_info; early++)
+ if (is_enabled(early))
+ pr_cont("%s%s", first++ == 0 ? "" : ",", early->name);
+ for (lsm = ordered_lsms; *lsm; lsm++)
+ if (is_enabled(*lsm))
+ pr_cont("%s%s", first++ == 0 ? "" : ",", (*lsm)->name);
+
+ pr_cont("\n");
+}
+
+/**
+ * lsm_early_cred - during initialization allocate a composite cred blob
+ * @cred: the cred that needs a blob
+ *
+ * Allocate the cred blob for all the modules
+ */
+static void __init lsm_early_cred(struct cred *cred)
+{
+ int rc = lsm_cred_alloc(cred, GFP_KERNEL);
+
+ if (rc)
+ panic("%s: Early cred alloc failed.\n", __func__);
+}
+
+/**
+ * lsm_early_task - during initialization allocate a composite task blob
+ * @task: the task that needs a blob
+ *
+ * Allocate the task blob for all the modules
+ */
+static void __init lsm_early_task(struct task_struct *task)
+{
+ int rc = lsm_task_alloc(task);
+
+ if (rc)
+ panic("%s: Early task alloc failed.\n", __func__);
+}
+
+static void __init ordered_lsm_init(void)
+{
+ struct lsm_info **lsm;
+
+ if (chosen_lsm_order) {
+ if (chosen_major_lsm) {
+ pr_warn("security=%s is ignored because it is superseded by lsm=%s\n",
+ chosen_major_lsm, chosen_lsm_order);
+ chosen_major_lsm = NULL;
+ }
+ ordered_lsm_parse(chosen_lsm_order, "cmdline");
+ } else
+ ordered_lsm_parse(builtin_lsm_order, "builtin");
+
+ for (lsm = ordered_lsms; *lsm; lsm++)
+ prepare_lsm(*lsm);
+
+ report_lsm_order();
+
+ init_debug("cred blob size = %d\n", blob_sizes.lbs_cred);
+ init_debug("file blob size = %d\n", blob_sizes.lbs_file);
+ init_debug("ib blob size = %d\n", blob_sizes.lbs_ib);
+ init_debug("inode blob size = %d\n", blob_sizes.lbs_inode);
+ init_debug("ipc blob size = %d\n", blob_sizes.lbs_ipc);
+#ifdef CONFIG_KEYS
+ init_debug("key blob size = %d\n", blob_sizes.lbs_key);
+#endif /* CONFIG_KEYS */
+ init_debug("msg_msg blob size = %d\n", blob_sizes.lbs_msg_msg);
+ init_debug("sock blob size = %d\n", blob_sizes.lbs_sock);
+ init_debug("superblock blob size = %d\n", blob_sizes.lbs_superblock);
+ init_debug("perf event blob size = %d\n", blob_sizes.lbs_perf_event);
+ init_debug("task blob size = %d\n", blob_sizes.lbs_task);
+ init_debug("tun device blob size = %d\n", blob_sizes.lbs_tun_dev);
+ init_debug("xattr slots = %d\n", blob_sizes.lbs_xattr_count);
+ init_debug("bdev blob size = %d\n", blob_sizes.lbs_bdev);
+ init_debug("bpf map blob size = %d\n", blob_sizes.lbs_bpf_map);
+ init_debug("bpf prog blob size = %d\n", blob_sizes.lbs_bpf_prog);
+ init_debug("bpf token blob size = %d\n", blob_sizes.lbs_bpf_token);
+
+ /*
+ * Create any kmem_caches needed for blobs
+ */
+ if (blob_sizes.lbs_file)
+ lsm_file_cache = kmem_cache_create("lsm_file_cache",
+ blob_sizes.lbs_file, 0,
+ SLAB_PANIC, NULL);
+ if (blob_sizes.lbs_inode)
+ lsm_inode_cache = kmem_cache_create("lsm_inode_cache",
+ blob_sizes.lbs_inode, 0,
+ SLAB_PANIC, NULL);
+
+ lsm_early_cred((struct cred *) current->cred);
+ lsm_early_task(current);
+ for (lsm = ordered_lsms; *lsm; lsm++)
+ initialize_lsm(*lsm);
+}
+
+static bool match_last_lsm(const char *list, const char *lsm)
+{
+ const char *last;
+
+ if (WARN_ON(!list || !lsm))
+ return false;
+ last = strrchr(list, ',');
+ if (last)
+ /* Pass the comma, strcmp() will check for '\0' */
+ last++;
+ else
+ last = list;
+ return !strcmp(last, lsm);
+}
+
+static int lsm_append(const char *new, char **result)
+{
+ char *cp;
+
+ if (*result == NULL) {
+ *result = kstrdup(new, GFP_KERNEL);
+ if (*result == NULL)
+ return -ENOMEM;
+ } else {
+ /* Check if it is the last registered name */
+ if (match_last_lsm(*result, new))
+ return 0;
+ cp = kasprintf(GFP_KERNEL, "%s,%s", *result, new);
+ if (cp == NULL)
+ return -ENOMEM;
+ kfree(*result);
+ *result = cp;
+ }
+ return 0;
+}
+
+static void __init lsm_static_call_init(struct security_hook_list *hl)
+{
+ struct lsm_static_call *scall = hl->scalls;
+ int i;
+
+ for (i = 0; i < MAX_LSM_COUNT; i++) {
+ /* Update the first static call that is not used yet */
+ if (!scall->hl) {
+ __static_call_update(scall->key, scall->trampoline,
+ hl->hook.lsm_func_addr);
+ scall->hl = hl;
+ static_branch_enable(scall->active);
+ return;
+ }
+ scall++;
+ }
+ panic("%s - Ran out of static slots.\n", __func__);
+}
+
+/**
+ * security_add_hooks - Add a modules hooks to the hook lists.
+ * @hooks: the hooks to add
+ * @count: the number of hooks to add
+ * @lsmid: the identification information for the security module
+ *
+ * Each LSM has to register its hooks with the infrastructure.
+ */
+void __init security_add_hooks(struct security_hook_list *hooks, int count,
+ const struct lsm_id *lsmid)
+{
+ int i;
+
+ /*
+ * A security module may call security_add_hooks() more
+ * than once during initialization, and LSM initialization
+ * is serialized. Landlock is one such case.
+ * Look at the previous entry, if there is one, for duplication.
+ */
+ if (lsm_active_cnt == 0 || lsm_idlist[lsm_active_cnt - 1] != lsmid) {
+ if (lsm_active_cnt >= MAX_LSM_COUNT)
+ panic("%s Too many LSMs registered.\n", __func__);
+ lsm_idlist[lsm_active_cnt++] = lsmid;
+ }
+
+ for (i = 0; i < count; i++) {
+ hooks[i].lsmid = lsmid;
+ lsm_static_call_init(&hooks[i]);
+ }
+
+ /*
+ * Don't try to append during early_security_init(), we'll come back
+ * and fix this up afterwards.
+ */
+ if (slab_is_available()) {
+ if (lsm_append(lsmid->name, &lsm_names) < 0)
+ panic("%s - Cannot get early memory.\n", __func__);
+ }
+}
+
+int __init early_security_init(void)
+{
+ struct lsm_info *lsm;
+
+ for (lsm = __start_early_lsm_info; lsm < __end_early_lsm_info; lsm++) {
+ if (!lsm->enabled)
+ lsm->enabled = &lsm_enabled_true;
+ prepare_lsm(lsm);
+ initialize_lsm(lsm);
+ }
+
+ return 0;
+}
+
+/**
+ * security_init - initializes the security framework
+ *
+ * This should be called early in the kernel initialization sequence.
+ */
+int __init security_init(void)
+{
+ struct lsm_info *lsm;
+
+ init_debug("legacy security=%s\n", chosen_major_lsm ? : " *unspecified*");
+ init_debug(" CONFIG_LSM=%s\n", builtin_lsm_order);
+ init_debug("boot arg lsm=%s\n", chosen_lsm_order ? : " *unspecified*");
+
+ /*
+ * Append the names of the early LSM modules now that kmalloc() is
+ * available
+ */
+ for (lsm = __start_early_lsm_info; lsm < __end_early_lsm_info; lsm++) {
+ init_debug(" early started: %s (%s)\n", lsm->name,
+ is_enabled(lsm) ? "enabled" : "disabled");
+ if (lsm->enabled)
+ lsm_append(lsm->name, &lsm_names);
+ }
+
+ /* Load LSMs in specified order. */
+ ordered_lsm_init();
+
+ return 0;
+}
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