diff options
Diffstat (limited to 'kernel/auditfilter.c')
| -rw-r--r-- | kernel/auditfilter.c | 1455 |
1 files changed, 1455 insertions, 0 deletions
diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c new file mode 100644 index 000000000..42d99896e --- /dev/null +++ b/kernel/auditfilter.c @@ -0,0 +1,1455 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* auditfilter.c -- filtering of audit events + * + * Copyright 2003-2004 Red Hat, Inc. + * Copyright 2005 Hewlett-Packard Development Company, L.P. + * Copyright 2005 IBM Corporation + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/kernel.h> +#include <linux/audit.h> +#include <linux/kthread.h> +#include <linux/mutex.h> +#include <linux/fs.h> +#include <linux/namei.h> +#include <linux/netlink.h> +#include <linux/sched.h> +#include <linux/slab.h> +#include <linux/security.h> +#include <net/net_namespace.h> +#include <net/sock.h> +#include "audit.h" + +/* + * Locking model: + * + * audit_filter_mutex: + * Synchronizes writes and blocking reads of audit's filterlist + * data. Rcu is used to traverse the filterlist and access + * contents of structs audit_entry, audit_watch and opaque + * LSM rules during filtering. If modified, these structures + * must be copied and replace their counterparts in the filterlist. + * An audit_parent struct is not accessed during filtering, so may + * be written directly provided audit_filter_mutex is held. + */ + +/* Audit filter lists, defined in <linux/audit.h> */ +struct list_head audit_filter_list[AUDIT_NR_FILTERS] = { + LIST_HEAD_INIT(audit_filter_list[0]), + LIST_HEAD_INIT(audit_filter_list[1]), + LIST_HEAD_INIT(audit_filter_list[2]), + LIST_HEAD_INIT(audit_filter_list[3]), + LIST_HEAD_INIT(audit_filter_list[4]), + LIST_HEAD_INIT(audit_filter_list[5]), + LIST_HEAD_INIT(audit_filter_list[6]), + LIST_HEAD_INIT(audit_filter_list[7]), +#if AUDIT_NR_FILTERS != 8 +#error Fix audit_filter_list initialiser +#endif +}; +static struct list_head audit_rules_list[AUDIT_NR_FILTERS] = { + LIST_HEAD_INIT(audit_rules_list[0]), + LIST_HEAD_INIT(audit_rules_list[1]), + LIST_HEAD_INIT(audit_rules_list[2]), + LIST_HEAD_INIT(audit_rules_list[3]), + LIST_HEAD_INIT(audit_rules_list[4]), + LIST_HEAD_INIT(audit_rules_list[5]), + LIST_HEAD_INIT(audit_rules_list[6]), + LIST_HEAD_INIT(audit_rules_list[7]), +}; + +DEFINE_MUTEX(audit_filter_mutex); + +static void audit_free_lsm_field(struct audit_field *f) +{ + switch (f->type) { + case AUDIT_SUBJ_USER: + case AUDIT_SUBJ_ROLE: + case AUDIT_SUBJ_TYPE: + case AUDIT_SUBJ_SEN: + case AUDIT_SUBJ_CLR: + case AUDIT_OBJ_USER: + case AUDIT_OBJ_ROLE: + case AUDIT_OBJ_TYPE: + case AUDIT_OBJ_LEV_LOW: + case AUDIT_OBJ_LEV_HIGH: + kfree(f->lsm_str); + security_audit_rule_free(f->lsm_rule); + } +} + +static inline void audit_free_rule(struct audit_entry *e) +{ + int i; + struct audit_krule *erule = &e->rule; + + /* some rules don't have associated watches */ + if (erule->watch) + audit_put_watch(erule->watch); + if (erule->fields) + for (i = 0; i < erule->field_count; i++) + audit_free_lsm_field(&erule->fields[i]); + kfree(erule->fields); + kfree(erule->filterkey); + kfree(e); +} + +void audit_free_rule_rcu(struct rcu_head *head) +{ + struct audit_entry *e = container_of(head, struct audit_entry, rcu); + audit_free_rule(e); +} + +/* Initialize an audit filterlist entry. */ +static inline struct audit_entry *audit_init_entry(u32 field_count) +{ + struct audit_entry *entry; + struct audit_field *fields; + + entry = kzalloc(sizeof(*entry), GFP_KERNEL); + if (unlikely(!entry)) + return NULL; + + fields = kcalloc(field_count, sizeof(*fields), GFP_KERNEL); + if (unlikely(!fields)) { + kfree(entry); + return NULL; + } + entry->rule.fields = fields; + + return entry; +} + +/* Unpack a filter field's string representation from user-space + * buffer. */ +char *audit_unpack_string(void **bufp, size_t *remain, size_t len) +{ + char *str; + + if (!*bufp || (len == 0) || (len > *remain)) + return ERR_PTR(-EINVAL); + + /* Of the currently implemented string fields, PATH_MAX + * defines the longest valid length. + */ + if (len > PATH_MAX) + return ERR_PTR(-ENAMETOOLONG); + + str = kmalloc(len + 1, GFP_KERNEL); + if (unlikely(!str)) + return ERR_PTR(-ENOMEM); + + memcpy(str, *bufp, len); + str[len] = 0; + *bufp += len; + *remain -= len; + + return str; +} + +/* Translate an inode field to kernel representation. */ +static inline int audit_to_inode(struct audit_krule *krule, + struct audit_field *f) +{ + if ((krule->listnr != AUDIT_FILTER_EXIT && + krule->listnr != AUDIT_FILTER_URING_EXIT) || + krule->inode_f || krule->watch || krule->tree || + (f->op != Audit_equal && f->op != Audit_not_equal)) + return -EINVAL; + + krule->inode_f = f; + return 0; +} + +static __u32 *classes[AUDIT_SYSCALL_CLASSES]; + +int __init audit_register_class(int class, unsigned *list) +{ + __u32 *p = kcalloc(AUDIT_BITMASK_SIZE, sizeof(__u32), GFP_KERNEL); + if (!p) + return -ENOMEM; + while (*list != ~0U) { + unsigned n = *list++; + if (n >= AUDIT_BITMASK_SIZE * 32 - AUDIT_SYSCALL_CLASSES) { + kfree(p); + return -EINVAL; + } + p[AUDIT_WORD(n)] |= AUDIT_BIT(n); + } + if (class >= AUDIT_SYSCALL_CLASSES || classes[class]) { + kfree(p); + return -EINVAL; + } + classes[class] = p; + return 0; +} + +int audit_match_class(int class, unsigned syscall) +{ + if (unlikely(syscall >= AUDIT_BITMASK_SIZE * 32)) + return 0; + if (unlikely(class >= AUDIT_SYSCALL_CLASSES || !classes[class])) + return 0; + return classes[class][AUDIT_WORD(syscall)] & AUDIT_BIT(syscall); +} + +#ifdef CONFIG_AUDITSYSCALL +static inline int audit_match_class_bits(int class, u32 *mask) +{ + int i; + + if (classes[class]) { + for (i = 0; i < AUDIT_BITMASK_SIZE; i++) + if (mask[i] & classes[class][i]) + return 0; + } + return 1; +} + +static int audit_match_signal(struct audit_entry *entry) +{ + struct audit_field *arch = entry->rule.arch_f; + + if (!arch) { + /* When arch is unspecified, we must check both masks on biarch + * as syscall number alone is ambiguous. */ + return (audit_match_class_bits(AUDIT_CLASS_SIGNAL, + entry->rule.mask) && + audit_match_class_bits(AUDIT_CLASS_SIGNAL_32, + entry->rule.mask)); + } + + switch(audit_classify_arch(arch->val)) { + case 0: /* native */ + return (audit_match_class_bits(AUDIT_CLASS_SIGNAL, + entry->rule.mask)); + case 1: /* 32bit on biarch */ + return (audit_match_class_bits(AUDIT_CLASS_SIGNAL_32, + entry->rule.mask)); + default: + return 1; + } +} +#endif + +/* Common user-space to kernel rule translation. */ +static inline struct audit_entry *audit_to_entry_common(struct audit_rule_data *rule) +{ + unsigned listnr; + struct audit_entry *entry; + int i, err; + + err = -EINVAL; + listnr = rule->flags & ~AUDIT_FILTER_PREPEND; + switch(listnr) { + default: + goto exit_err; +#ifdef CONFIG_AUDITSYSCALL + case AUDIT_FILTER_ENTRY: + pr_err("AUDIT_FILTER_ENTRY is deprecated\n"); + goto exit_err; + case AUDIT_FILTER_EXIT: + case AUDIT_FILTER_URING_EXIT: + case AUDIT_FILTER_TASK: +#endif + case AUDIT_FILTER_USER: + case AUDIT_FILTER_EXCLUDE: + case AUDIT_FILTER_FS: + ; + } + if (unlikely(rule->action == AUDIT_POSSIBLE)) { + pr_err("AUDIT_POSSIBLE is deprecated\n"); + goto exit_err; + } + if (rule->action != AUDIT_NEVER && rule->action != AUDIT_ALWAYS) + goto exit_err; + if (rule->field_count > AUDIT_MAX_FIELDS) + goto exit_err; + + err = -ENOMEM; + entry = audit_init_entry(rule->field_count); + if (!entry) + goto exit_err; + + entry->rule.flags = rule->flags & AUDIT_FILTER_PREPEND; + entry->rule.listnr = listnr; + entry->rule.action = rule->action; + entry->rule.field_count = rule->field_count; + + for (i = 0; i < AUDIT_BITMASK_SIZE; i++) + entry->rule.mask[i] = rule->mask[i]; + + for (i = 0; i < AUDIT_SYSCALL_CLASSES; i++) { + int bit = AUDIT_BITMASK_SIZE * 32 - i - 1; + __u32 *p = &entry->rule.mask[AUDIT_WORD(bit)]; + __u32 *class; + + if (!(*p & AUDIT_BIT(bit))) + continue; + *p &= ~AUDIT_BIT(bit); + class = classes[i]; + if (class) { + int j; + for (j = 0; j < AUDIT_BITMASK_SIZE; j++) + entry->rule.mask[j] |= class[j]; + } + } + + return entry; + +exit_err: + return ERR_PTR(err); +} + +static u32 audit_ops[] = +{ + [Audit_equal] = AUDIT_EQUAL, + [Audit_not_equal] = AUDIT_NOT_EQUAL, + [Audit_bitmask] = AUDIT_BIT_MASK, + [Audit_bittest] = AUDIT_BIT_TEST, + [Audit_lt] = AUDIT_LESS_THAN, + [Audit_gt] = AUDIT_GREATER_THAN, + [Audit_le] = AUDIT_LESS_THAN_OR_EQUAL, + [Audit_ge] = AUDIT_GREATER_THAN_OR_EQUAL, +}; + +static u32 audit_to_op(u32 op) +{ + u32 n; + for (n = Audit_equal; n < Audit_bad && audit_ops[n] != op; n++) + ; + return n; +} + +/* check if an audit field is valid */ +static int audit_field_valid(struct audit_entry *entry, struct audit_field *f) +{ + switch (f->type) { + case AUDIT_MSGTYPE: + if (entry->rule.listnr != AUDIT_FILTER_EXCLUDE && + entry->rule.listnr != AUDIT_FILTER_USER) + return -EINVAL; + break; + case AUDIT_FSTYPE: + if (entry->rule.listnr != AUDIT_FILTER_FS) + return -EINVAL; + break; + case AUDIT_PERM: + if (entry->rule.listnr == AUDIT_FILTER_URING_EXIT) + return -EINVAL; + break; + } + + switch (entry->rule.listnr) { + case AUDIT_FILTER_FS: + switch(f->type) { + case AUDIT_FSTYPE: + case AUDIT_FILTERKEY: + break; + default: + return -EINVAL; + } + } + + /* Check for valid field type and op */ + switch (f->type) { + case AUDIT_ARG0: + case AUDIT_ARG1: + case AUDIT_ARG2: + case AUDIT_ARG3: + case AUDIT_PERS: /* <uapi/linux/personality.h> */ + case AUDIT_DEVMINOR: + /* all ops are valid */ + break; + case AUDIT_UID: + case AUDIT_EUID: + case AUDIT_SUID: + case AUDIT_FSUID: + case AUDIT_LOGINUID: + case AUDIT_OBJ_UID: + case AUDIT_GID: + case AUDIT_EGID: + case AUDIT_SGID: + case AUDIT_FSGID: + case AUDIT_OBJ_GID: + case AUDIT_PID: + case AUDIT_MSGTYPE: + case AUDIT_PPID: + case AUDIT_DEVMAJOR: + case AUDIT_EXIT: + case AUDIT_SUCCESS: + case AUDIT_INODE: + case AUDIT_SESSIONID: + case AUDIT_SUBJ_SEN: + case AUDIT_SUBJ_CLR: + case AUDIT_OBJ_LEV_LOW: + case AUDIT_OBJ_LEV_HIGH: + case AUDIT_SADDR_FAM: + /* bit ops are only useful on syscall args */ + if (f->op == Audit_bitmask || f->op == Audit_bittest) + return -EINVAL; + break; + case AUDIT_SUBJ_USER: + case AUDIT_SUBJ_ROLE: + case AUDIT_SUBJ_TYPE: + case AUDIT_OBJ_USER: + case AUDIT_OBJ_ROLE: + case AUDIT_OBJ_TYPE: + case AUDIT_WATCH: + case AUDIT_DIR: + case AUDIT_FILTERKEY: + case AUDIT_LOGINUID_SET: + case AUDIT_ARCH: + case AUDIT_FSTYPE: + case AUDIT_PERM: + case AUDIT_FILETYPE: + case AUDIT_FIELD_COMPARE: + case AUDIT_EXE: + /* only equal and not equal valid ops */ + if (f->op != Audit_not_equal && f->op != Audit_equal) + return -EINVAL; + break; + default: + /* field not recognized */ + return -EINVAL; + } + + /* Check for select valid field values */ + switch (f->type) { + case AUDIT_LOGINUID_SET: + if ((f->val != 0) && (f->val != 1)) + return -EINVAL; + break; + case AUDIT_PERM: + if (f->val & ~15) + return -EINVAL; + break; + case AUDIT_FILETYPE: + if (f->val & ~S_IFMT) + return -EINVAL; + break; + case AUDIT_FIELD_COMPARE: + if (f->val > AUDIT_MAX_FIELD_COMPARE) + return -EINVAL; + break; + case AUDIT_SADDR_FAM: + if (f->val >= AF_MAX) + return -EINVAL; + break; + default: + break; + } + + return 0; +} + +/* Translate struct audit_rule_data to kernel's rule representation. */ +static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data, + size_t datasz) +{ + int err = 0; + struct audit_entry *entry; + void *bufp; + size_t remain = datasz - sizeof(struct audit_rule_data); + int i; + char *str; + struct audit_fsnotify_mark *audit_mark; + + entry = audit_to_entry_common(data); + if (IS_ERR(entry)) + goto exit_nofree; + + bufp = data->buf; + for (i = 0; i < data->field_count; i++) { + struct audit_field *f = &entry->rule.fields[i]; + u32 f_val; + + err = -EINVAL; + + f->op = audit_to_op(data->fieldflags[i]); + if (f->op == Audit_bad) + goto exit_free; + + f->type = data->fields[i]; + f_val = data->values[i]; + + /* Support legacy tests for a valid loginuid */ + if ((f->type == AUDIT_LOGINUID) && (f_val == AUDIT_UID_UNSET)) { + f->type = AUDIT_LOGINUID_SET; + f_val = 0; + entry->rule.pflags |= AUDIT_LOGINUID_LEGACY; + } + + err = audit_field_valid(entry, f); + if (err) + goto exit_free; + + err = -EINVAL; + switch (f->type) { + case AUDIT_LOGINUID: + case AUDIT_UID: + case AUDIT_EUID: + case AUDIT_SUID: + case AUDIT_FSUID: + case AUDIT_OBJ_UID: + f->uid = make_kuid(current_user_ns(), f_val); + if (!uid_valid(f->uid)) + goto exit_free; + break; + case AUDIT_GID: + case AUDIT_EGID: + case AUDIT_SGID: + case AUDIT_FSGID: + case AUDIT_OBJ_GID: + f->gid = make_kgid(current_user_ns(), f_val); + if (!gid_valid(f->gid)) + goto exit_free; + break; + case AUDIT_ARCH: + f->val = f_val; + entry->rule.arch_f = f; + break; + case AUDIT_SUBJ_USER: + case AUDIT_SUBJ_ROLE: + case AUDIT_SUBJ_TYPE: + case AUDIT_SUBJ_SEN: + case AUDIT_SUBJ_CLR: + case AUDIT_OBJ_USER: + case AUDIT_OBJ_ROLE: + case AUDIT_OBJ_TYPE: + case AUDIT_OBJ_LEV_LOW: + case AUDIT_OBJ_LEV_HIGH: + str = audit_unpack_string(&bufp, &remain, f_val); + if (IS_ERR(str)) { + err = PTR_ERR(str); + goto exit_free; + } + entry->rule.buflen += f_val; + f->lsm_str = str; + err = security_audit_rule_init(f->type, f->op, str, + (void **)&f->lsm_rule); + /* Keep currently invalid fields around in case they + * become valid after a policy reload. */ + if (err == -EINVAL) { + pr_warn("audit rule for LSM \'%s\' is invalid\n", + str); + err = 0; + } else if (err) + goto exit_free; + break; + case AUDIT_WATCH: + str = audit_unpack_string(&bufp, &remain, f_val); + if (IS_ERR(str)) { + err = PTR_ERR(str); + goto exit_free; + } + err = audit_to_watch(&entry->rule, str, f_val, f->op); + if (err) { + kfree(str); + goto exit_free; + } + entry->rule.buflen += f_val; + break; + case AUDIT_DIR: + str = audit_unpack_string(&bufp, &remain, f_val); + if (IS_ERR(str)) { + err = PTR_ERR(str); + goto exit_free; + } + err = audit_make_tree(&entry->rule, str, f->op); + kfree(str); + if (err) + goto exit_free; + entry->rule.buflen += f_val; + break; + case AUDIT_INODE: + f->val = f_val; + err = audit_to_inode(&entry->rule, f); + if (err) + goto exit_free; + break; + case AUDIT_FILTERKEY: + if (entry->rule.filterkey || f_val > AUDIT_MAX_KEY_LEN) + goto exit_free; + str = audit_unpack_string(&bufp, &remain, f_val); + if (IS_ERR(str)) { + err = PTR_ERR(str); + goto exit_free; + } + entry->rule.buflen += f_val; + entry->rule.filterkey = str; + break; + case AUDIT_EXE: + if (entry->rule.exe || f_val > PATH_MAX) + goto exit_free; + str = audit_unpack_string(&bufp, &remain, f_val); + if (IS_ERR(str)) { + err = PTR_ERR(str); + goto exit_free; + } + audit_mark = audit_alloc_mark(&entry->rule, str, f_val); + if (IS_ERR(audit_mark)) { + kfree(str); + err = PTR_ERR(audit_mark); + goto exit_free; + } + entry->rule.buflen += f_val; + entry->rule.exe = audit_mark; + break; + default: + f->val = f_val; + break; + } + } + + if (entry->rule.inode_f && entry->rule.inode_f->op == Audit_not_equal) + entry->rule.inode_f = NULL; + +exit_nofree: + return entry; + +exit_free: + if (entry->rule.tree) + audit_put_tree(entry->rule.tree); /* that's the temporary one */ + if (entry->rule.exe) + audit_remove_mark(entry->rule.exe); /* that's the template one */ + audit_free_rule(entry); + return ERR_PTR(err); +} + +/* Pack a filter field's string representation into data block. */ +static inline size_t audit_pack_string(void **bufp, const char *str) +{ + size_t len = strlen(str); + + memcpy(*bufp, str, len); + *bufp += len; + + return len; +} + +/* Translate kernel rule representation to struct audit_rule_data. */ +static struct audit_rule_data *audit_krule_to_data(struct audit_krule *krule) +{ + struct audit_rule_data *data; + void *bufp; + int i; + + data = kmalloc(struct_size(data, buf, krule->buflen), GFP_KERNEL); + if (unlikely(!data)) + return NULL; + memset(data, 0, sizeof(*data)); + + data->flags = krule->flags | krule->listnr; + data->action = krule->action; + data->field_count = krule->field_count; + bufp = data->buf; + for (i = 0; i < data->field_count; i++) { + struct audit_field *f = &krule->fields[i]; + + data->fields[i] = f->type; + data->fieldflags[i] = audit_ops[f->op]; + switch(f->type) { + case AUDIT_SUBJ_USER: + case AUDIT_SUBJ_ROLE: + case AUDIT_SUBJ_TYPE: + case AUDIT_SUBJ_SEN: + case AUDIT_SUBJ_CLR: + case AUDIT_OBJ_USER: + case AUDIT_OBJ_ROLE: + case AUDIT_OBJ_TYPE: + case AUDIT_OBJ_LEV_LOW: + case AUDIT_OBJ_LEV_HIGH: + data->buflen += data->values[i] = + audit_pack_string(&bufp, f->lsm_str); + break; + case AUDIT_WATCH: + data->buflen += data->values[i] = + audit_pack_string(&bufp, + audit_watch_path(krule->watch)); + break; + case AUDIT_DIR: + data->buflen += data->values[i] = + audit_pack_string(&bufp, + audit_tree_path(krule->tree)); + break; + case AUDIT_FILTERKEY: + data->buflen += data->values[i] = + audit_pack_string(&bufp, krule->filterkey); + break; + case AUDIT_EXE: + data->buflen += data->values[i] = + audit_pack_string(&bufp, audit_mark_path(krule->exe)); + break; + case AUDIT_LOGINUID_SET: + if (krule->pflags & AUDIT_LOGINUID_LEGACY && !f->val) { + data->fields[i] = AUDIT_LOGINUID; + data->values[i] = AUDIT_UID_UNSET; + break; + } + fallthrough; /* if set */ + default: + data->values[i] = f->val; + } + } + for (i = 0; i < AUDIT_BITMASK_SIZE; i++) data->mask[i] = krule->mask[i]; + + return data; +} + +/* Compare two rules in kernel format. Considered success if rules + * don't match. */ +static int audit_compare_rule(struct audit_krule *a, struct audit_krule *b) +{ + int i; + + if (a->flags != b->flags || + a->pflags != b->pflags || + a->listnr != b->listnr || + a->action != b->action || + a->field_count != b->field_count) + return 1; + + for (i = 0; i < a->field_count; i++) { + if (a->fields[i].type != b->fields[i].type || + a->fields[i].op != b->fields[i].op) + return 1; + + switch(a->fields[i].type) { + case AUDIT_SUBJ_USER: + case AUDIT_SUBJ_ROLE: + case AUDIT_SUBJ_TYPE: + case AUDIT_SUBJ_SEN: + case AUDIT_SUBJ_CLR: + case AUDIT_OBJ_USER: + case AUDIT_OBJ_ROLE: + case AUDIT_OBJ_TYPE: + case AUDIT_OBJ_LEV_LOW: + case AUDIT_OBJ_LEV_HIGH: + if (strcmp(a->fields[i].lsm_str, b->fields[i].lsm_str)) + return 1; + break; + case AUDIT_WATCH: + if (strcmp(audit_watch_path(a->watch), + audit_watch_path(b->watch))) + return 1; + break; + case AUDIT_DIR: + if (strcmp(audit_tree_path(a->tree), + audit_tree_path(b->tree))) + return 1; + break; + case AUDIT_FILTERKEY: + /* both filterkeys exist based on above type compare */ + if (strcmp(a->filterkey, b->filterkey)) + return 1; + break; + case AUDIT_EXE: + /* both paths exist based on above type compare */ + if (strcmp(audit_mark_path(a->exe), + audit_mark_path(b->exe))) + return 1; + break; + case AUDIT_UID: + case AUDIT_EUID: + case AUDIT_SUID: + case AUDIT_FSUID: + case AUDIT_LOGINUID: + case AUDIT_OBJ_UID: + if (!uid_eq(a->fields[i].uid, b->fields[i].uid)) + return 1; + break; + case AUDIT_GID: + case AUDIT_EGID: + case AUDIT_SGID: + case AUDIT_FSGID: + case AUDIT_OBJ_GID: + if (!gid_eq(a->fields[i].gid, b->fields[i].gid)) + return 1; + break; + default: + if (a->fields[i].val != b->fields[i].val) + return 1; + } + } + + for (i = 0; i < AUDIT_BITMASK_SIZE; i++) + if (a->mask[i] != b->mask[i]) + return 1; + + return 0; +} + +/* Duplicate LSM field information. The lsm_rule is opaque, so must be + * re-initialized. */ +static inline int audit_dupe_lsm_field(struct audit_field *df, + struct audit_field *sf) +{ + int ret = 0; + char *lsm_str; + + /* our own copy of lsm_str */ + lsm_str = kstrdup(sf->lsm_str, GFP_KERNEL); + if (unlikely(!lsm_str)) + return -ENOMEM; + df->lsm_str = lsm_str; + + /* our own (refreshed) copy of lsm_rule */ + ret = security_audit_rule_init(df->type, df->op, df->lsm_str, + (void **)&df->lsm_rule); + /* Keep currently invalid fields around in case they + * become valid after a policy reload. */ + if (ret == -EINVAL) { + pr_warn("audit rule for LSM \'%s\' is invalid\n", + df->lsm_str); + ret = 0; + } + + return ret; +} + +/* Duplicate an audit rule. This will be a deep copy with the exception + * of the watch - that pointer is carried over. The LSM specific fields + * will be updated in the copy. The point is to be able to replace the old + * rule with the new rule in the filterlist, then free the old rule. + * The rlist element is undefined; list manipulations are handled apart from + * the initial copy. */ +struct audit_entry *audit_dupe_rule(struct audit_krule *old) +{ + u32 fcount = old->field_count; + struct audit_entry *entry; + struct audit_krule *new; + char *fk; + int i, err = 0; + + entry = audit_init_entry(fcount); + if (unlikely(!entry)) + return ERR_PTR(-ENOMEM); + + new = &entry->rule; + new->flags = old->flags; + new->pflags = old->pflags; + new->listnr = old->listnr; + new->action = old->action; + for (i = 0; i < AUDIT_BITMASK_SIZE; i++) + new->mask[i] = old->mask[i]; + new->prio = old->prio; + new->buflen = old->buflen; + new->inode_f = old->inode_f; + new->field_count = old->field_count; + + /* + * note that we are OK with not refcounting here; audit_match_tree() + * never dereferences tree and we can't get false positives there + * since we'd have to have rule gone from the list *and* removed + * before the chunks found by lookup had been allocated, i.e. before + * the beginning of list scan. + */ + new->tree = old->tree; + memcpy(new->fields, old->fields, sizeof(struct audit_field) * fcount); + + /* deep copy this information, updating the lsm_rule fields, because + * the originals will all be freed when the old rule is freed. */ + for (i = 0; i < fcount; i++) { + switch (new->fields[i].type) { + case AUDIT_SUBJ_USER: + case AUDIT_SUBJ_ROLE: + case AUDIT_SUBJ_TYPE: + case AUDIT_SUBJ_SEN: + case AUDIT_SUBJ_CLR: + case AUDIT_OBJ_USER: + case AUDIT_OBJ_ROLE: + case AUDIT_OBJ_TYPE: + case AUDIT_OBJ_LEV_LOW: + case AUDIT_OBJ_LEV_HIGH: + err = audit_dupe_lsm_field(&new->fields[i], + &old->fields[i]); + break; + case AUDIT_FILTERKEY: + fk = kstrdup(old->filterkey, GFP_KERNEL); + if (unlikely(!fk)) + err = -ENOMEM; + else + new->filterkey = fk; + break; + case AUDIT_EXE: + err = audit_dupe_exe(new, old); + break; + } + if (err) { + if (new->exe) + audit_remove_mark(new->exe); + audit_free_rule(entry); + return ERR_PTR(err); + } + } + + if (old->watch) { + audit_get_watch(old->watch); + new->watch = old->watch; + } + + return entry; +} + +/* Find an existing audit rule. + * Caller must hold audit_filter_mutex to prevent stale rule data. */ +static struct audit_entry *audit_find_rule(struct audit_entry *entry, + struct list_head **p) +{ + struct audit_entry *e, *found = NULL; + struct list_head *list; + int h; + + if (entry->rule.inode_f) { + h = audit_hash_ino(entry->rule.inode_f->val); + *p = list = &audit_inode_hash[h]; + } else if (entry->rule.watch) { + /* we don't know the inode number, so must walk entire hash */ + for (h = 0; h < AUDIT_INODE_BUCKETS; h++) { + list = &audit_inode_hash[h]; + list_for_each_entry(e, list, list) + if (!audit_compare_rule(&entry->rule, &e->rule)) { + found = e; + goto out; + } + } + goto out; + } else { + *p = list = &audit_filter_list[entry->rule.listnr]; + } + + list_for_each_entry(e, list, list) + if (!audit_compare_rule(&entry->rule, &e->rule)) { + found = e; + goto out; + } + +out: + return found; +} + +static u64 prio_low = ~0ULL/2; +static u64 prio_high = ~0ULL/2 - 1; + +/* Add rule to given filterlist if not a duplicate. */ +static inline int audit_add_rule(struct audit_entry *entry) +{ + struct audit_entry *e; + struct audit_watch *watch = entry->rule.watch; + struct audit_tree *tree = entry->rule.tree; + struct list_head *list; + int err = 0; +#ifdef CONFIG_AUDITSYSCALL + int dont_count = 0; + + /* If any of these, don't count towards total */ + switch(entry->rule.listnr) { + case AUDIT_FILTER_USER: + case AUDIT_FILTER_EXCLUDE: + case AUDIT_FILTER_FS: + dont_count = 1; + } +#endif + + mutex_lock(&audit_filter_mutex); + e = audit_find_rule(entry, &list); + if (e) { + mutex_unlock(&audit_filter_mutex); + err = -EEXIST; + /* normally audit_add_tree_rule() will free it on failure */ + if (tree) + audit_put_tree(tree); + return err; + } + + if (watch) { + /* audit_filter_mutex is dropped and re-taken during this call */ + err = audit_add_watch(&entry->rule, &list); + if (err) { + mutex_unlock(&audit_filter_mutex); + /* + * normally audit_add_tree_rule() will free it + * on failure + */ + if (tree) + audit_put_tree(tree); + return err; + } + } + if (tree) { + err = audit_add_tree_rule(&entry->rule); + if (err) { + mutex_unlock(&audit_filter_mutex); + return err; + } + } + + entry->rule.prio = ~0ULL; + if (entry->rule.listnr == AUDIT_FILTER_EXIT || + entry->rule.listnr == AUDIT_FILTER_URING_EXIT) { + if (entry->rule.flags & AUDIT_FILTER_PREPEND) + entry->rule.prio = ++prio_high; + else + entry->rule.prio = --prio_low; + } + + if (entry->rule.flags & AUDIT_FILTER_PREPEND) { + list_add(&entry->rule.list, + &audit_rules_list[entry->rule.listnr]); + list_add_rcu(&entry->list, list); + entry->rule.flags &= ~AUDIT_FILTER_PREPEND; + } else { + list_add_tail(&entry->rule.list, + &audit_rules_list[entry->rule.listnr]); + list_add_tail_rcu(&entry->list, list); + } +#ifdef CONFIG_AUDITSYSCALL + if (!dont_count) + audit_n_rules++; + + if (!audit_match_signal(entry)) + audit_signals++; +#endif + mutex_unlock(&audit_filter_mutex); + + return err; +} + +/* Remove an existing rule from filterlist. */ +int audit_del_rule(struct audit_entry *entry) +{ + struct audit_entry *e; + struct audit_tree *tree = entry->rule.tree; + struct list_head *list; + int ret = 0; +#ifdef CONFIG_AUDITSYSCALL + int dont_count = 0; + + /* If any of these, don't count towards total */ + switch(entry->rule.listnr) { + case AUDIT_FILTER_USER: + case AUDIT_FILTER_EXCLUDE: + case AUDIT_FILTER_FS: + dont_count = 1; + } +#endif + + mutex_lock(&audit_filter_mutex); + e = audit_find_rule(entry, &list); + if (!e) { + ret = -ENOENT; + goto out; + } + + if (e->rule.watch) + audit_remove_watch_rule(&e->rule); + + if (e->rule.tree) + audit_remove_tree_rule(&e->rule); + + if (e->rule.exe) + audit_remove_mark_rule(&e->rule); + +#ifdef CONFIG_AUDITSYSCALL + if (!dont_count) + audit_n_rules--; + + if (!audit_match_signal(entry)) + audit_signals--; +#endif + + list_del_rcu(&e->list); + list_del(&e->rule.list); + call_rcu(&e->rcu, audit_free_rule_rcu); + +out: + mutex_unlock(&audit_filter_mutex); + + if (tree) + audit_put_tree(tree); /* that's the temporary one */ + + return ret; +} + +/* List rules using struct audit_rule_data. */ +static void audit_list_rules(int seq, struct sk_buff_head *q) +{ + struct sk_buff *skb; + struct audit_krule *r; + int i; + + /* This is a blocking read, so use audit_filter_mutex instead of rcu + * iterator to sync with list writers. */ + for (i=0; i<AUDIT_NR_FILTERS; i++) { + list_for_each_entry(r, &audit_rules_list[i], list) { + struct audit_rule_data *data; + + data = audit_krule_to_data(r); + if (unlikely(!data)) + break; + skb = audit_make_reply(seq, AUDIT_LIST_RULES, 0, 1, + data, + struct_size(data, buf, data->buflen)); + if (skb) + skb_queue_tail(q, skb); + kfree(data); + } + } + skb = audit_make_reply(seq, AUDIT_LIST_RULES, 1, 1, NULL, 0); + if (skb) + skb_queue_tail(q, skb); +} + +/* Log rule additions and removals */ +static void audit_log_rule_change(char *action, struct audit_krule *rule, int res) +{ + struct audit_buffer *ab; + + if (!audit_enabled) + return; + + ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_CONFIG_CHANGE); + if (!ab) + return; + audit_log_session_info(ab); + audit_log_task_context(ab); + audit_log_format(ab, " op=%s", action); + audit_log_key(ab, rule->filterkey); + audit_log_format(ab, " list=%d res=%d", rule->listnr, res); + audit_log_end(ab); +} + +/** + * audit_rule_change - apply all rules to the specified message type + * @type: audit message type + * @seq: netlink audit message sequence (serial) number + * @data: payload data + * @datasz: size of payload data + */ +int audit_rule_change(int type, int seq, void *data, size_t datasz) +{ + int err = 0; + struct audit_entry *entry; + + switch (type) { + case AUDIT_ADD_RULE: + entry = audit_data_to_entry(data, datasz); + if (IS_ERR(entry)) + return PTR_ERR(entry); + err = audit_add_rule(entry); + audit_log_rule_change("add_rule", &entry->rule, !err); + break; + case AUDIT_DEL_RULE: + entry = audit_data_to_entry(data, datasz); + if (IS_ERR(entry)) + return PTR_ERR(entry); + err = audit_del_rule(entry); + audit_log_rule_change("remove_rule", &entry->rule, !err); + break; + default: + WARN_ON(1); + return -EINVAL; + } + + if (err || type == AUDIT_DEL_RULE) { + if (entry->rule.exe) + audit_remove_mark(entry->rule.exe); + audit_free_rule(entry); + } + + return err; +} + +/** + * audit_list_rules_send - list the audit rules + * @request_skb: skb of request we are replying to (used to target the reply) + * @seq: netlink audit message sequence (serial) number + */ +int audit_list_rules_send(struct sk_buff *request_skb, int seq) +{ + struct task_struct *tsk; + struct audit_netlink_list *dest; + + /* We can't just spew out the rules here because we might fill + * the available socket buffer space and deadlock waiting for + * auditctl to read from it... which isn't ever going to + * happen if we're actually running in the context of auditctl + * trying to _send_ the stuff */ + + dest = kmalloc(sizeof(*dest), GFP_KERNEL); + if (!dest) + return -ENOMEM; + dest->net = get_net(sock_net(NETLINK_CB(request_skb).sk)); + dest->portid = NETLINK_CB(request_skb).portid; + skb_queue_head_init(&dest->q); + + mutex_lock(&audit_filter_mutex); + audit_list_rules(seq, &dest->q); + mutex_unlock(&audit_filter_mutex); + + tsk = kthread_run(audit_send_list_thread, dest, "audit_send_list"); + if (IS_ERR(tsk)) { + skb_queue_purge(&dest->q); + put_net(dest->net); + kfree(dest); + return PTR_ERR(tsk); + } + + return 0; +} + +int audit_comparator(u32 left, u32 op, u32 right) +{ + switch (op) { + case Audit_equal: + return (left == right); + case Audit_not_equal: + return (left != right); + case Audit_lt: + return (left < right); + case Audit_le: + return (left <= right); + case Audit_gt: + return (left > right); + case Audit_ge: + return (left >= right); + case Audit_bitmask: + return (left & right); + case Audit_bittest: + return ((left & right) == right); + default: + return 0; + } +} + +int audit_uid_comparator(kuid_t left, u32 op, kuid_t right) +{ + switch (op) { + case Audit_equal: + return uid_eq(left, right); + case Audit_not_equal: + return !uid_eq(left, right); + case Audit_lt: + return uid_lt(left, right); + case Audit_le: + return uid_lte(left, right); + case Audit_gt: + return uid_gt(left, right); + case Audit_ge: + return uid_gte(left, right); + case Audit_bitmask: + case Audit_bittest: + default: + return 0; + } +} + +int audit_gid_comparator(kgid_t left, u32 op, kgid_t right) +{ + switch (op) { + case Audit_equal: + return gid_eq(left, right); + case Audit_not_equal: + return !gid_eq(left, right); + case Audit_lt: + return gid_lt(left, right); + case Audit_le: + return gid_lte(left, right); + case Audit_gt: + return gid_gt(left, right); + case Audit_ge: + return gid_gte(left, right); + case Audit_bitmask: + case Audit_bittest: + default: + return 0; + } +} + +/** + * parent_len - find the length of the parent portion of a pathname + * @path: pathname of which to determine length + */ +int parent_len(const char *path) +{ + int plen; + const char *p; + + plen = strlen(path); + + if (plen == 0) + return plen; + + /* disregard trailing slashes */ + p = path + plen - 1; + while ((*p == '/') && (p > path)) + p--; + + /* walk backward until we find the next slash or hit beginning */ + while ((*p != '/') && (p > path)) + p--; + + /* did we find a slash? Then increment to include it in path */ + if (*p == '/') + p++; + + return p - path; +} + +/** + * audit_compare_dname_path - compare given dentry name with last component in + * given path. Return of 0 indicates a match. + * @dname: dentry name that we're comparing + * @path: full pathname that we're comparing + * @parentlen: length of the parent if known. Passing in AUDIT_NAME_FULL + * here indicates that we must compute this value. + */ +int audit_compare_dname_path(const struct qstr *dname, const char *path, int parentlen) +{ + int dlen, pathlen; + const char *p; + + dlen = dname->len; + pathlen = strlen(path); + if (pathlen < dlen) + return 1; + + parentlen = parentlen == AUDIT_NAME_FULL ? parent_len(path) : parentlen; + if (pathlen - parentlen != dlen) + return 1; + + p = path + parentlen; + + return strncmp(p, dname->name, dlen); +} + +int audit_filter(int msgtype, unsigned int listtype) +{ + struct audit_entry *e; + int ret = 1; /* Audit by default */ + + rcu_read_lock(); + list_for_each_entry_rcu(e, &audit_filter_list[listtype], list) { + int i, result = 0; + + for (i = 0; i < e->rule.field_count; i++) { + struct audit_field *f = &e->rule.fields[i]; + pid_t pid; + u32 sid; + + switch (f->type) { + case AUDIT_PID: + pid = task_pid_nr(current); + result = audit_comparator(pid, f->op, f->val); + break; + case AUDIT_UID: + result = audit_uid_comparator(current_uid(), f->op, f->uid); + break; + case AUDIT_GID: + result = audit_gid_comparator(current_gid(), f->op, f->gid); + break; + case AUDIT_LOGINUID: + result = audit_uid_comparator(audit_get_loginuid(current), + f->op, f->uid); + break; + case AUDIT_LOGINUID_SET: + result = audit_comparator(audit_loginuid_set(current), + f->op, f->val); + break; + case AUDIT_MSGTYPE: + result = audit_comparator(msgtype, f->op, f->val); + break; + case AUDIT_SUBJ_USER: + case AUDIT_SUBJ_ROLE: + case AUDIT_SUBJ_TYPE: + case AUDIT_SUBJ_SEN: + case AUDIT_SUBJ_CLR: + if (f->lsm_rule) { + security_current_getsecid_subj(&sid); + result = security_audit_rule_match(sid, + f->type, f->op, f->lsm_rule); + } + break; + case AUDIT_EXE: + result = audit_exe_compare(current, e->rule.exe); + if (f->op == Audit_not_equal) + result = !result; + break; + default: + goto unlock_and_return; + } + if (result < 0) /* error */ + goto unlock_and_return; + if (!result) + break; + } + if (result > 0) { + if (e->rule.action == AUDIT_NEVER || listtype == AUDIT_FILTER_EXCLUDE) + ret = 0; + break; + } + } +unlock_and_return: + rcu_read_unlock(); + return ret; +} + +static int update_lsm_rule(struct audit_krule *r) +{ + struct audit_entry *entry = container_of(r, struct audit_entry, rule); + struct audit_entry *nentry; + int err = 0; + + if (!security_audit_rule_known(r)) + return 0; + + nentry = audit_dupe_rule(r); + if (entry->rule.exe) + audit_remove_mark(entry->rule.exe); + if (IS_ERR(nentry)) { + /* save the first error encountered for the + * return value */ + err = PTR_ERR(nentry); + audit_panic("error updating LSM filters"); + if (r->watch) + list_del(&r->rlist); + list_del_rcu(&entry->list); + list_del(&r->list); + } else { + if (r->watch || r->tree) + list_replace_init(&r->rlist, &nentry->rule.rlist); + list_replace_rcu(&entry->list, &nentry->list); + list_replace(&r->list, &nentry->rule.list); + } + call_rcu(&entry->rcu, audit_free_rule_rcu); + + return err; +} + +/* This function will re-initialize the lsm_rule field of all applicable rules. + * It will traverse the filter lists serarching for rules that contain LSM + * specific filter fields. When such a rule is found, it is copied, the + * LSM field is re-initialized, and the old rule is replaced with the + * updated rule. */ +int audit_update_lsm_rules(void) +{ + struct audit_krule *r, *n; + int i, err = 0; + + /* audit_filter_mutex synchronizes the writers */ + mutex_lock(&audit_filter_mutex); + + for (i = 0; i < AUDIT_NR_FILTERS; i++) { + list_for_each_entry_safe(r, n, &audit_rules_list[i], list) { + int res = update_lsm_rule(r); + if (!err) + err = res; + } + } + mutex_unlock(&audit_filter_mutex); + + return err; +} |