From 93315ed6dd12dacfc941f9eb8ca0293aadf99793 Mon Sep 17 00:00:00 2001 From: Amy Griffis Date: Tue, 7 Feb 2006 12:05:27 -0500 Subject: [PATCH] audit string fields interface + consumer Updated patch to dynamically allocate audit rule fields in kernel's internal representation. Added unlikely() calls for testing memory allocation result. Amy Griffis wrote: [Wed Jan 11 2006, 02:02:31PM EST] > Modify audit's kernel-userspace interface to allow the specification > of string fields in audit rules. > > Signed-off-by: Amy Griffis Signed-off-by: Al Viro (cherry picked from 5ffc4a863f92351b720fe3e9c5cd647accff9e03 commit) --- kernel/auditfilter.c | 467 +++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 357 insertions(+), 110 deletions(-) (limited to 'kernel/auditfilter.c') diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c index a3a32752f973..686d514a3518 100644 --- a/kernel/auditfilter.c +++ b/kernel/auditfilter.c @@ -40,52 +40,279 @@ struct list_head audit_filter_list[AUDIT_NR_FILTERS] = { #endif }; -/* Copy rule from user-space to kernel-space. Called from - * audit_add_rule during AUDIT_ADD. */ -static inline int audit_copy_rule(struct audit_rule *d, struct audit_rule *s) +static inline void audit_free_rule(struct audit_entry *e) { + kfree(e->rule.fields); + kfree(e); +} + +static inline void audit_free_rule_rcu(struct rcu_head *head) +{ + struct audit_entry *e = container_of(head, struct audit_entry, rcu); + audit_free_rule(e); +} + +/* Unpack a filter field's string representation from user-space + * buffer. */ +static __attribute__((unused)) 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; +} + +/* Common user-space to kernel rule translation. */ +static inline struct audit_entry *audit_to_entry_common(struct audit_rule *rule) +{ + unsigned listnr; + struct audit_entry *entry; + struct audit_field *fields; + int i, err; + + err = -EINVAL; + listnr = rule->flags & ~AUDIT_FILTER_PREPEND; + switch(listnr) { + default: + goto exit_err; + case AUDIT_FILTER_USER: + case AUDIT_FILTER_TYPE: +#ifdef CONFIG_AUDITSYSCALL + case AUDIT_FILTER_ENTRY: + case AUDIT_FILTER_EXIT: + case AUDIT_FILTER_TASK: +#endif + ; + } + if (rule->action != AUDIT_NEVER && rule->action != AUDIT_POSSIBLE && + rule->action != AUDIT_ALWAYS) + goto exit_err; + if (rule->field_count > AUDIT_MAX_FIELDS) + goto exit_err; + + err = -ENOMEM; + entry = kmalloc(sizeof(*entry), GFP_KERNEL); + if (unlikely(!entry)) + goto exit_err; + fields = kmalloc(sizeof(*fields) * rule->field_count, GFP_KERNEL); + if (unlikely(!fields)) { + kfree(entry); + goto exit_err; + } + + memset(&entry->rule, 0, sizeof(struct audit_krule)); + memset(fields, 0, sizeof(struct audit_field)); + + entry->rule.flags = rule->flags & AUDIT_FILTER_PREPEND; + entry->rule.listnr = listnr; + entry->rule.action = rule->action; + entry->rule.field_count = rule->field_count; + entry->rule.fields = fields; + + for (i = 0; i < AUDIT_BITMASK_SIZE; i++) + entry->rule.mask[i] = rule->mask[i]; + + return entry; + +exit_err: + return ERR_PTR(err); +} + +/* Translate struct audit_rule to kernel's rule respresentation. + * Exists for backward compatibility with userspace. */ +static struct audit_entry *audit_rule_to_entry(struct audit_rule *rule) +{ + struct audit_entry *entry; + int err = 0; int i; - if (s->action != AUDIT_NEVER - && s->action != AUDIT_POSSIBLE - && s->action != AUDIT_ALWAYS) - return -1; - if (s->field_count < 0 || s->field_count > AUDIT_MAX_FIELDS) - return -1; - if ((s->flags & ~AUDIT_FILTER_PREPEND) >= AUDIT_NR_FILTERS) - return -1; - - d->flags = s->flags; - d->action = s->action; - d->field_count = s->field_count; - for (i = 0; i < d->field_count; i++) { - d->fields[i] = s->fields[i]; - d->values[i] = s->values[i]; + entry = audit_to_entry_common(rule); + if (IS_ERR(entry)) + goto exit_nofree; + + for (i = 0; i < rule->field_count; i++) { + struct audit_field *f = &entry->rule.fields[i]; + + if (rule->fields[i] & AUDIT_UNUSED_BITS) { + err = -EINVAL; + goto exit_free; + } + + f->op = rule->fields[i] & (AUDIT_NEGATE|AUDIT_OPERATORS); + f->type = rule->fields[i] & ~(AUDIT_NEGATE|AUDIT_OPERATORS); + f->val = rule->values[i]; + + entry->rule.vers_ops = (f->op & AUDIT_OPERATORS) ? 2 : 1; + if (f->op & AUDIT_NEGATE) + f->op |= AUDIT_NOT_EQUAL; + else if (!(f->op & AUDIT_OPERATORS)) + f->op |= AUDIT_EQUAL; + f->op &= ~AUDIT_NEGATE; } - for (i = 0; i < AUDIT_BITMASK_SIZE; i++) d->mask[i] = s->mask[i]; - return 0; + +exit_nofree: + return entry; + +exit_free: + audit_free_rule(entry); + return ERR_PTR(err); } -/* Check to see if two rules are identical. It is called from - * audit_add_rule during AUDIT_ADD and - * audit_del_rule during AUDIT_DEL. */ -static int audit_compare_rule(struct audit_rule *a, struct audit_rule *b) +/* Translate struct audit_rule_data to kernel's rule respresentation. */ +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; - if (a->flags != b->flags) - return 1; + entry = audit_to_entry_common((struct audit_rule *)data); + if (IS_ERR(entry)) + goto exit_nofree; - if (a->action != b->action) - return 1; + bufp = data->buf; + entry->rule.vers_ops = 2; + for (i = 0; i < data->field_count; i++) { + struct audit_field *f = &entry->rule.fields[i]; + + err = -EINVAL; + if (!(data->fieldflags[i] & AUDIT_OPERATORS) || + data->fieldflags[i] & ~AUDIT_OPERATORS) + goto exit_free; + + f->op = data->fieldflags[i] & AUDIT_OPERATORS; + f->type = data->fields[i]; + switch(f->type) { + /* call type-specific conversion routines here */ + default: + f->val = data->values[i]; + } + } + +exit_nofree: + return entry; + +exit_free: + 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, char *str) +{ + size_t len = strlen(str); + + memcpy(*bufp, str, len); + *bufp += len; + + return len; +} + +/* Translate kernel rule respresentation to struct audit_rule. + * Exists for backward compatibility with userspace. */ +static struct audit_rule *audit_krule_to_rule(struct audit_krule *krule) +{ + struct audit_rule *rule; + int i; + + rule = kmalloc(sizeof(*rule), GFP_KERNEL); + if (unlikely(!rule)) + return ERR_PTR(-ENOMEM); + memset(rule, 0, sizeof(*rule)); + + rule->flags = krule->flags | krule->listnr; + rule->action = krule->action; + rule->field_count = krule->field_count; + for (i = 0; i < rule->field_count; i++) { + rule->values[i] = krule->fields[i].val; + rule->fields[i] = krule->fields[i].type; + + if (krule->vers_ops == 1) { + if (krule->fields[i].op & AUDIT_NOT_EQUAL) + rule->fields[i] |= AUDIT_NEGATE; + } else { + rule->fields[i] |= krule->fields[i].op; + } + } + for (i = 0; i < AUDIT_BITMASK_SIZE; i++) rule->mask[i] = krule->mask[i]; + + return rule; +} - if (a->field_count != b->field_count) +/* Translate kernel rule respresentation 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(sizeof(*data) + krule->buflen, GFP_KERNEL); + if (unlikely(!data)) + return ERR_PTR(-ENOMEM); + 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] = f->op; + switch(f->type) { + /* call type-specific conversion routines here */ + 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->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] != b->fields[i] - || a->values[i] != b->values[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) { + /* call type-specific comparison routines here */ + default: + if (a->fields[i].val != b->fields[i].val) + return 1; + } } for (i = 0; i < AUDIT_BITMASK_SIZE; i++) @@ -95,41 +322,21 @@ static int audit_compare_rule(struct audit_rule *a, struct audit_rule *b) return 0; } -/* Note that audit_add_rule and audit_del_rule are called via - * audit_receive() in audit.c, and are protected by +/* Add rule to given filterlist if not a duplicate. Protected by * audit_netlink_sem. */ -static inline int audit_add_rule(struct audit_rule *rule, +static inline int audit_add_rule(struct audit_entry *entry, struct list_head *list) { - struct audit_entry *entry; - int i; + struct audit_entry *e; /* Do not use the _rcu iterator here, since this is the only * addition routine. */ - list_for_each_entry(entry, list, list) { - if (!audit_compare_rule(rule, &entry->rule)) + list_for_each_entry(e, list, list) { + if (!audit_compare_rule(&entry->rule, &e->rule)) return -EEXIST; } - for (i = 0; i < rule->field_count; i++) { - if (rule->fields[i] & AUDIT_UNUSED_BITS) - return -EINVAL; - if ( rule->fields[i] & AUDIT_NEGATE) - rule->fields[i] |= AUDIT_NOT_EQUAL; - else if ( (rule->fields[i] & AUDIT_OPERATORS) == 0 ) - rule->fields[i] |= AUDIT_EQUAL; - rule->fields[i] &= ~AUDIT_NEGATE; - } - - if (!(entry = kmalloc(sizeof(*entry), GFP_KERNEL))) - return -ENOMEM; - if (audit_copy_rule(&entry->rule, rule)) { - kfree(entry); - return -EINVAL; - } - if (entry->rule.flags & AUDIT_FILTER_PREPEND) { - entry->rule.flags &= ~AUDIT_FILTER_PREPEND; list_add_rcu(&entry->list, list); } else { list_add_tail_rcu(&entry->list, list); @@ -138,16 +345,9 @@ static inline int audit_add_rule(struct audit_rule *rule, return 0; } -static inline void audit_free_rule(struct rcu_head *head) -{ - struct audit_entry *e = container_of(head, struct audit_entry, rcu); - kfree(e); -} - -/* Note that audit_add_rule and audit_del_rule are called via - * audit_receive() in audit.c, and are protected by +/* Remove an existing rule from filterlist. Protected by * audit_netlink_sem. */ -static inline int audit_del_rule(struct audit_rule *rule, +static inline int audit_del_rule(struct audit_entry *entry, struct list_head *list) { struct audit_entry *e; @@ -155,16 +355,18 @@ static inline int audit_del_rule(struct audit_rule *rule, /* Do not use the _rcu iterator here, since this is the only * deletion routine. */ list_for_each_entry(e, list, list) { - if (!audit_compare_rule(rule, &e->rule)) { + if (!audit_compare_rule(&entry->rule, &e->rule)) { list_del_rcu(&e->list); - call_rcu(&e->rcu, audit_free_rule); + call_rcu(&e->rcu, audit_free_rule_rcu); return 0; } } return -ENOENT; /* No matching rule */ } -static int audit_list_rules(void *_dest) +/* List rules using struct audit_rule. Exists for backward + * compatibility with userspace. */ +static int audit_list(void *_dest) { int pid, seq; int *dest = _dest; @@ -180,9 +382,16 @@ static int audit_list_rules(void *_dest) /* The *_rcu iterators not needed here because we are always called with audit_netlink_sem held. */ for (i=0; irule); + if (unlikely(!rule)) + break; audit_send_reply(pid, seq, AUDIT_LIST, 0, 1, - &entry->rule, sizeof(entry->rule)); + rule, sizeof(*rule)); + kfree(rule); + } } audit_send_reply(pid, seq, AUDIT_LIST, 1, 1, NULL, 0); @@ -190,6 +399,40 @@ static int audit_list_rules(void *_dest) return 0; } +/* List rules using struct audit_rule_data. */ +static int audit_list_rules(void *_dest) +{ + int pid, seq; + int *dest = _dest; + struct audit_entry *e; + int i; + + pid = dest[0]; + seq = dest[1]; + kfree(dest); + + down(&audit_netlink_sem); + + /* The *_rcu iterators not needed here because we are + always called with audit_netlink_sem held. */ + for (i=0; irule); + if (unlikely(!data)) + break; + audit_send_reply(pid, seq, AUDIT_LIST_RULES, 0, 1, + data, sizeof(*data)); + kfree(data); + } + } + audit_send_reply(pid, seq, AUDIT_LIST_RULES, 1, 1, NULL, 0); + + up(&audit_netlink_sem); + return 0; +} + /** * audit_receive_filter - apply all rules to the specified message type * @type: audit message type @@ -197,18 +440,20 @@ static int audit_list_rules(void *_dest) * @uid: target uid for netlink audit messages * @seq: netlink audit message sequence (serial) number * @data: payload data + * @datasz: size of payload data * @loginuid: loginuid of sender */ int audit_receive_filter(int type, int pid, int uid, int seq, void *data, - uid_t loginuid) + size_t datasz, uid_t loginuid) { struct task_struct *tsk; int *dest; - int err = 0; - unsigned listnr; + int err = 0; + struct audit_entry *entry; switch (type) { case AUDIT_LIST: + case AUDIT_LIST_RULES: /* 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 @@ -221,41 +466,48 @@ int audit_receive_filter(int type, int pid, int uid, int seq, void *data, dest[0] = pid; dest[1] = seq; - tsk = kthread_run(audit_list_rules, dest, "audit_list_rules"); + if (type == AUDIT_LIST) + tsk = kthread_run(audit_list, dest, "audit_list"); + else + tsk = kthread_run(audit_list_rules, dest, + "audit_list_rules"); if (IS_ERR(tsk)) { kfree(dest); err = PTR_ERR(tsk); } break; case AUDIT_ADD: - listnr = ((struct audit_rule *)data)->flags & ~AUDIT_FILTER_PREPEND; - switch(listnr) { - default: - return -EINVAL; - - case AUDIT_FILTER_USER: - case AUDIT_FILTER_TYPE: -#ifdef CONFIG_AUDITSYSCALL - case AUDIT_FILTER_ENTRY: - case AUDIT_FILTER_EXIT: - case AUDIT_FILTER_TASK: -#endif - ; - } - err = audit_add_rule(data, &audit_filter_list[listnr]); + case AUDIT_ADD_RULE: + if (type == AUDIT_ADD) + entry = audit_rule_to_entry(data); + else + entry = audit_data_to_entry(data, datasz); + if (IS_ERR(entry)) + return PTR_ERR(entry); + + err = audit_add_rule(entry, + &audit_filter_list[entry->rule.listnr]); if (!err) audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE, "auid=%u added an audit rule\n", loginuid); + else + audit_free_rule(entry); break; case AUDIT_DEL: - listnr =((struct audit_rule *)data)->flags & ~AUDIT_FILTER_PREPEND; - if (listnr >= AUDIT_NR_FILTERS) - return -EINVAL; - - err = audit_del_rule(data, &audit_filter_list[listnr]); + case AUDIT_DEL_RULE: + if (type == AUDIT_DEL) + entry = audit_rule_to_entry(data); + else + entry = audit_data_to_entry(data, datasz); + if (IS_ERR(entry)) + return PTR_ERR(entry); + + err = audit_del_rule(entry, + &audit_filter_list[entry->rule.listnr]); if (!err) audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE, "auid=%u removed an audit rule\n", loginuid); + audit_free_rule(entry); break; default: return -EINVAL; @@ -287,29 +539,27 @@ int audit_comparator(const u32 left, const u32 op, const u32 right) static int audit_filter_user_rules(struct netlink_skb_parms *cb, - struct audit_rule *rule, + struct audit_krule *rule, enum audit_state *state) { int i; for (i = 0; i < rule->field_count; i++) { - u32 field = rule->fields[i] & ~AUDIT_OPERATORS; - u32 op = rule->fields[i] & AUDIT_OPERATORS; - u32 value = rule->values[i]; + struct audit_field *f = &rule->fields[i]; int result = 0; - switch (field) { + switch (f->type) { case AUDIT_PID: - result = audit_comparator(cb->creds.pid, op, value); + result = audit_comparator(cb->creds.pid, f->op, f->val); break; case AUDIT_UID: - result = audit_comparator(cb->creds.uid, op, value); + result = audit_comparator(cb->creds.uid, f->op, f->val); break; case AUDIT_GID: - result = audit_comparator(cb->creds.gid, op, value); + result = audit_comparator(cb->creds.gid, f->op, f->val); break; case AUDIT_LOGINUID: - result = audit_comparator(cb->loginuid, op, value); + result = audit_comparator(cb->loginuid, f->op, f->val); break; } @@ -354,14 +604,11 @@ int audit_filter_type(int type) list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_TYPE], list) { - struct audit_rule *rule = &e->rule; int i; - for (i = 0; i < rule->field_count; i++) { - u32 field = rule->fields[i] & ~AUDIT_OPERATORS; - u32 op = rule->fields[i] & AUDIT_OPERATORS; - u32 value = rule->values[i]; - if ( field == AUDIT_MSGTYPE ) { - result = audit_comparator(type, op, value); + for (i = 0; i < e->rule.field_count; i++) { + struct audit_field *f = &e->rule.fields[i]; + if (f->type == AUDIT_MSGTYPE) { + result = audit_comparator(type, f->op, f->val); if (!result) break; } -- cgit v1.2.1