diff options
Diffstat (limited to 'security/lsm_init.c')
| -rw-r--r-- | security/lsm_init.c | 564 |
1 files changed, 564 insertions, 0 deletions
diff --git a/security/lsm_init.c b/security/lsm_init.c new file mode 100644 index 000000000000..05bd52e6b1f2 --- /dev/null +++ b/security/lsm_init.c @@ -0,0 +1,564 @@ +// 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" + +/* LSM enabled constants. */ +static __initdata int lsm_enabled_true = 1; +static __initdata int lsm_enabled_false = 0; + +/* 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[]; + +/* Number of "early" LSMs */ +static __initdata unsigned int lsm_count_early; + +/* Build and boot-time LSM ordering. */ +static __initconst const char *const lsm_order_builtin = CONFIG_LSM; +static __initdata const char *lsm_order_cmdline; +static __initdata const char *lsm_order_legacy; + +/* Ordered list of LSMs to initialize. */ +static __initdata struct lsm_info *lsm_order[MAX_LSM_COUNT + 1]; +static __initdata struct lsm_info *lsm_exclusive; + +#define lsm_order_for_each(iter) \ + for ((iter) = lsm_order; *(iter); (iter)++) +#define lsm_for_each_raw(iter) \ + for ((iter) = __start_lsm_info; \ + (iter) < __end_lsm_info; (iter)++) +#define lsm_early_for_each_raw(iter) \ + for ((iter) = __start_early_lsm_info; \ + (iter) < __end_early_lsm_info; (iter)++) + +#define lsm_initcall(level) \ + ({ \ + int _r, _rc = 0; \ + struct lsm_info **_lp, *_l; \ + lsm_order_for_each(_lp) { \ + _l = *_lp; \ + if (!_l->initcall_##level) \ + continue; \ + lsm_pr_dbg("running %s %s initcall", \ + _l->id->name, #level); \ + _r = _l->initcall_##level(); \ + if (_r) { \ + pr_warn("failed LSM %s %s initcall with errno %d\n", \ + _l->id->name, #level, _r); \ + if (!_rc) \ + _rc = _r; \ + } \ + } \ + _rc; \ + }) + +/** + * lsm_choose_security - Legacy "major" LSM selection + * @str: kernel command line parameter + */ +static int __init lsm_choose_security(char *str) +{ + lsm_order_legacy = str; + return 1; +} +__setup("security=", lsm_choose_security); + +/** + * lsm_choose_lsm - Modern LSM selection + * @str: kernel command line parameter + */ +static int __init lsm_choose_lsm(char *str) +{ + lsm_order_cmdline = str; + return 1; +} +__setup("lsm=", lsm_choose_lsm); + +/** + * lsm_debug_enable - Enable LSM framework debugging + * @str: kernel command line parameter + * + * Currently we only provide debug info during LSM initialization, but we may + * want to expand this in the future. + */ +static int __init lsm_debug_enable(char *str) +{ + lsm_debug = true; + return 1; +} +__setup("lsm.debug", lsm_debug_enable); + +/** + * lsm_enabled_set - Mark a LSM as enabled + * @lsm: LSM definition + * @enabled: enabled flag + */ +static void __init lsm_enabled_set(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 || + lsm->enabled == &lsm_enabled_true || + lsm->enabled == &lsm_enabled_false) { + lsm->enabled = enabled ? &lsm_enabled_true : &lsm_enabled_false; + } else { + *lsm->enabled = enabled; + } +} + +/** + * lsm_is_enabled - Determine if a LSM is enabled + * @lsm: LSM definition + */ +static inline bool lsm_is_enabled(struct lsm_info *lsm) +{ + return (lsm->enabled ? *lsm->enabled : false); +} + +/** + * lsm_order_exists - Determine if a LSM exists in the ordered list + * @lsm: LSM definition + */ +static bool __init lsm_order_exists(struct lsm_info *lsm) +{ + struct lsm_info **check; + + lsm_order_for_each(check) { + if (*check == lsm) + return true; + } + + return false; +} + +/** + * lsm_order_append - Append a LSM to the ordered list + * @lsm: LSM definition + * @src: source of the addition + * + * Append @lsm to the enabled LSM array after ensuring that it hasn't been + * explicitly disabled, is a duplicate entry, or would run afoul of the + * LSM_FLAG_EXCLUSIVE logic. + */ +static void __init lsm_order_append(struct lsm_info *lsm, const char *src) +{ + /* Ignore duplicate selections. */ + if (lsm_order_exists(lsm)) + return; + + /* Skip explicitly disabled LSMs. */ + if (lsm->enabled && !lsm_is_enabled(lsm)) { + lsm_pr_dbg("skip previously disabled LSM %s:%s\n", + src, lsm->id->name); + return; + } + + if (lsm_active_cnt == MAX_LSM_COUNT) { + pr_warn("exceeded maximum LSM count on %s:%s\n", + src, lsm->id->name); + lsm_enabled_set(lsm, false); + return; + } + + if (lsm->flags & LSM_FLAG_EXCLUSIVE) { + if (lsm_exclusive) { + lsm_pr_dbg("skip exclusive LSM conflict %s:%s\n", + src, lsm->id->name); + lsm_enabled_set(lsm, false); + return; + } else { + lsm_pr_dbg("select exclusive LSM %s:%s\n", + src, lsm->id->name); + lsm_exclusive = lsm; + } + } + + lsm_enabled_set(lsm, true); + lsm_order[lsm_active_cnt] = lsm; + lsm_idlist[lsm_active_cnt++] = lsm->id; + + lsm_pr_dbg("enabling LSM %s:%s\n", src, lsm->id->name); +} + +/** + * lsm_order_parse - Parse the comma delimited LSM list + * @list: LSM list + * @src: source of the list + */ +static void __init lsm_order_parse(const char *list, const char *src) +{ + struct lsm_info *lsm; + char *sep, *name, *next; + + /* Handle any Legacy LSM exclusions if one was specified. */ + if (lsm_order_legacy) { + /* + * 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. + */ + lsm_for_each_raw(lsm) { + if ((lsm->flags & LSM_FLAG_LEGACY_MAJOR) && + strcmp(lsm->id->name, lsm_order_legacy)) { + lsm_enabled_set(lsm, false); + lsm_pr_dbg("skip legacy LSM conflict %s:%s\n", + src, lsm->id->name); + } + } + } + + /* LSM_ORDER_FIRST */ + lsm_for_each_raw(lsm) { + if (lsm->order == LSM_ORDER_FIRST) + lsm_order_append(lsm, "first"); + } + + /* Normal or "mutable" LSMs */ + sep = kstrdup(list, GFP_KERNEL); + next = sep; + /* Walk the list, looking for matching LSMs. */ + while ((name = strsep(&next, ",")) != NULL) { + lsm_for_each_raw(lsm) { + if (!strcmp(lsm->id->name, name) && + lsm->order == LSM_ORDER_MUTABLE) + lsm_order_append(lsm, src); + } + } + kfree(sep); + + /* Legacy LSM if specified. */ + if (lsm_order_legacy) { + lsm_for_each_raw(lsm) { + if (!strcmp(lsm->id->name, lsm_order_legacy)) + lsm_order_append(lsm, src); + } + } + + /* LSM_ORDER_LAST */ + lsm_for_each_raw(lsm) { + if (lsm->order == LSM_ORDER_LAST) + lsm_order_append(lsm, "last"); + } + + /* Disable all LSMs not previously enabled. */ + lsm_for_each_raw(lsm) { + if (lsm_order_exists(lsm)) + continue; + lsm_enabled_set(lsm, false); + lsm_pr_dbg("skip disabled LSM %s:%s\n", src, lsm->id->name); + } +} + +/** + * lsm_blob_size_update - Update the LSM blob size and offset information + * @sz_req: the requested additional blob size + * @sz_cur: the existing blob size + */ +static void __init lsm_blob_size_update(unsigned int *sz_req, + unsigned int *sz_cur) +{ + unsigned int offset; + + if (*sz_req == 0) + return; + + offset = ALIGN(*sz_cur, sizeof(void *)); + *sz_cur = offset + *sz_req; + *sz_req = offset; +} + +/** + * lsm_prepare - Prepare the LSM framework for a new LSM + * @lsm: LSM definition + */ +static void __init lsm_prepare(struct lsm_info *lsm) +{ + struct lsm_blob_sizes *blobs = lsm->blobs; + + if (!blobs) + return; + + /* Register the LSM blob sizes. */ + blobs = lsm->blobs; + lsm_blob_size_update(&blobs->lbs_cred, &blob_sizes.lbs_cred); + lsm_blob_size_update(&blobs->lbs_file, &blob_sizes.lbs_file); + lsm_blob_size_update(&blobs->lbs_ib, &blob_sizes.lbs_ib); + /* inode blob gets an rcu_head in addition to LSM blobs. */ + if (blobs->lbs_inode && blob_sizes.lbs_inode == 0) + blob_sizes.lbs_inode = sizeof(struct rcu_head); + lsm_blob_size_update(&blobs->lbs_inode, &blob_sizes.lbs_inode); + lsm_blob_size_update(&blobs->lbs_ipc, &blob_sizes.lbs_ipc); + lsm_blob_size_update(&blobs->lbs_key, &blob_sizes.lbs_key); + lsm_blob_size_update(&blobs->lbs_msg_msg, &blob_sizes.lbs_msg_msg); + lsm_blob_size_update(&blobs->lbs_perf_event, + &blob_sizes.lbs_perf_event); + lsm_blob_size_update(&blobs->lbs_sock, &blob_sizes.lbs_sock); + lsm_blob_size_update(&blobs->lbs_superblock, + &blob_sizes.lbs_superblock); + lsm_blob_size_update(&blobs->lbs_task, &blob_sizes.lbs_task); + lsm_blob_size_update(&blobs->lbs_tun_dev, &blob_sizes.lbs_tun_dev); + lsm_blob_size_update(&blobs->lbs_xattr_count, + &blob_sizes.lbs_xattr_count); + lsm_blob_size_update(&blobs->lbs_bdev, &blob_sizes.lbs_bdev); + lsm_blob_size_update(&blobs->lbs_bpf_map, &blob_sizes.lbs_bpf_map); + lsm_blob_size_update(&blobs->lbs_bpf_prog, &blob_sizes.lbs_bpf_prog); + lsm_blob_size_update(&blobs->lbs_bpf_token, &blob_sizes.lbs_bpf_token); +} + +/** + * lsm_init_single - Initialize a given LSM + * @lsm: LSM definition + */ +static void __init lsm_init_single(struct lsm_info *lsm) +{ + int ret; + + if (!lsm_is_enabled(lsm)) + return; + + lsm_pr_dbg("initializing %s\n", lsm->id->name); + ret = lsm->init(); + WARN(ret, "%s failed to initialize: %d\n", lsm->id->name, ret); +} + +/** + * lsm_static_call_init - Initialize a LSM's static calls + * @hl: LSM hook list + */ +static int __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 0; + } + scall++; + } + + return -ENOSPC; +} + +/** + * security_add_hooks - Add a LSM's hooks to the LSM framework's hook lists + * @hooks: LSM hooks to add + * @count: number of hooks to add + * @lsmid: identification information for the LSM + * + * Each LSM has to register its hooks with the LSM framework. + */ +void __init security_add_hooks(struct security_hook_list *hooks, int count, + const struct lsm_id *lsmid) +{ + int i; + + for (i = 0; i < count; i++) { + hooks[i].lsmid = lsmid; + if (lsm_static_call_init(&hooks[i])) + panic("exhausted LSM callback slots with LSM %s\n", + lsmid->name); + } +} + +/** + * early_security_init - Initialize the early LSMs + */ +int __init early_security_init(void) +{ + struct lsm_info *lsm; + + /* NOTE: lsm_pr_dbg() doesn't work here as lsm_debug is not yet set */ + + lsm_early_for_each_raw(lsm) { + lsm_enabled_set(lsm, true); + lsm_order_append(lsm, "early"); + lsm_prepare(lsm); + lsm_init_single(lsm); + lsm_count_early++; + } + + return 0; +} + +/** + * security_init - Initializes the LSM framework + * + * This should be called early in the kernel initialization sequence. + */ +int __init security_init(void) +{ + unsigned int cnt; + struct lsm_info **lsm; + + if (lsm_debug) { + struct lsm_info *i; + + cnt = 0; + lsm_pr("available LSMs: "); + lsm_early_for_each_raw(i) + lsm_pr_cont("%s%s(E)", (cnt++ ? "," : ""), i->id->name); + lsm_for_each_raw(i) + lsm_pr_cont("%s%s", (cnt++ ? "," : ""), i->id->name); + lsm_pr_cont("\n"); + + lsm_pr("built-in LSM config: %s\n", lsm_order_builtin); + + lsm_pr("legacy LSM parameter: %s\n", lsm_order_legacy); + lsm_pr("boot LSM parameter: %s\n", lsm_order_cmdline); + + /* see the note about lsm_pr_dbg() in early_security_init() */ + lsm_early_for_each_raw(i) + lsm_pr("enabled LSM early:%s\n", i->id->name); + } + + if (lsm_order_cmdline) { + if (lsm_order_legacy) + lsm_order_legacy = NULL; + lsm_order_parse(lsm_order_cmdline, "cmdline"); + } else + lsm_order_parse(lsm_order_builtin, "builtin"); + + lsm_order_for_each(lsm) + lsm_prepare(*lsm); + + if (lsm_debug) { + lsm_pr("blob(cred) size %d\n", blob_sizes.lbs_cred); + lsm_pr("blob(file) size %d\n", blob_sizes.lbs_file); + lsm_pr("blob(ib) size %d\n", blob_sizes.lbs_ib); + lsm_pr("blob(inode) size %d\n", blob_sizes.lbs_inode); + lsm_pr("blob(ipc) size %d\n", blob_sizes.lbs_ipc); + lsm_pr("blob(key) size %d\n", blob_sizes.lbs_key); + lsm_pr("blob(msg_msg)_size %d\n", blob_sizes.lbs_msg_msg); + lsm_pr("blob(sock) size %d\n", blob_sizes.lbs_sock); + lsm_pr("blob(superblock) size %d\n", blob_sizes.lbs_superblock); + lsm_pr("blob(perf_event) size %d\n", blob_sizes.lbs_perf_event); + lsm_pr("blob(task) size %d\n", blob_sizes.lbs_task); + lsm_pr("blob(tun_dev) size %d\n", blob_sizes.lbs_tun_dev); + lsm_pr("blob(xattr) count %d\n", blob_sizes.lbs_xattr_count); + lsm_pr("blob(bdev) size %d\n", blob_sizes.lbs_bdev); + lsm_pr("blob(bpf_map) size %d\n", blob_sizes.lbs_bpf_map); + lsm_pr("blob(bpf_prog) size %d\n", blob_sizes.lbs_bpf_prog); + lsm_pr("blob(bpf_token) size %d\n", blob_sizes.lbs_bpf_token); + } + + 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); + + if (lsm_cred_alloc((struct cred *)unrcu_pointer(current->cred), + GFP_KERNEL)) + panic("early LSM cred alloc failed\n"); + if (lsm_task_alloc(current)) + panic("early LSM task alloc failed\n"); + + cnt = 0; + lsm_order_for_each(lsm) { + /* skip the "early" LSMs as they have already been setup */ + if (cnt++ < lsm_count_early) + continue; + lsm_init_single(*lsm); + } + + return 0; +} + +/** + * security_initcall_pure - Run the LSM pure initcalls + */ +static int __init security_initcall_pure(void) +{ + int rc_adr, rc_lsm; + + rc_adr = min_addr_init(); + rc_lsm = lsm_initcall(pure); + + return (rc_adr ? rc_adr : rc_lsm); +} +pure_initcall(security_initcall_pure); + +/** + * security_initcall_early - Run the LSM early initcalls + */ +static int __init security_initcall_early(void) +{ + return lsm_initcall(early); +} +early_initcall(security_initcall_early); + +/** + * security_initcall_core - Run the LSM core initcalls + */ +static int __init security_initcall_core(void) +{ + int rc_sfs, rc_lsm; + + rc_sfs = securityfs_init(); + rc_lsm = lsm_initcall(core); + + return (rc_sfs ? rc_sfs : rc_lsm); +} +core_initcall(security_initcall_core); + +/** + * security_initcall_subsys - Run the LSM subsys initcalls + */ +static int __init security_initcall_subsys(void) +{ + return lsm_initcall(subsys); +} +subsys_initcall(security_initcall_subsys); + +/** + * security_initcall_fs - Run the LSM fs initcalls + */ +static int __init security_initcall_fs(void) +{ + return lsm_initcall(fs); +} +fs_initcall(security_initcall_fs); + +/** + * security_initcall_device - Run the LSM device initcalls + */ +static int __init security_initcall_device(void) +{ + return lsm_initcall(device); +} +device_initcall(security_initcall_device); + +/** + * security_initcall_late - Run the LSM late initcalls + */ +static int __init security_initcall_late(void) +{ + int rc; + + rc = lsm_initcall(late); + lsm_pr_dbg("all enabled LSMs fully activated\n"); + call_blocking_lsm_notifier(LSM_STARTED_ALL, NULL); + + return rc; +} +late_initcall(security_initcall_late); |