Re: [PATCH] Split audit filtering into auditfilter.c

I've committed this to my tree locally and checked that it builds with all three possible combinations of CONFIG_AUDIT, CONFIG_AUDITSYSCALL. My DSL line is down at the moment so I'll push it to the git tree later or tomorrow. This mail will be delayed too, but it'll probably get out as soon as the line comes back, and long before I notice and respond by pushing to the git tree. [AUDIT] Fix audit record filtering with !CONFIG_AUDITSYSCALL This fixes the per-user and per-message-type filtering when syscall auditing isn't enabled. Signed-off-by: David Woodhouse <dwmw2(a)infradead.org&gt; diff --git a/include/linux/audit.h b/include/linux/audit.h index 36e5090..8817141 100644 --- a/include/linux/audit.h +++ b/include/linux/audit.h @@ -278,8 +278,6 @@ static inline void audit_inode_child(con } /* Private API (for audit.c only) */ -extern int audit_receive_filter(int type, int pid, int uid, int seq, - void *data, uid_t loginuid); extern unsigned int audit_serial(void); extern void auditsc_get_stamp(struct audit_context *ctx, struct timespec *t, unsigned int *serial); @@ -290,8 +288,6 @@ extern int audit_socketcall(int nargs, u extern int audit_sockaddr(int len, void *addr); extern int audit_avc_path(struct dentry *dentry, struct vfsmount *mnt); extern void audit_signal_info(int sig, struct task_struct *t); -extern int audit_filter_user(struct netlink_skb_parms *cb, int type); -extern int audit_filter_exclude(int type); extern char *audit_ipc_context(struct kern_ipc_perm *ipcp); extern int audit_set_macxattr(const char *name); #else @@ -305,7 +301,6 @@ extern int audit_set_macxattr(const char #define __audit_inode_child(d,i,p) do { ; } while (0) #define audit_inode(n,i,f) do { ; } while (0) #define audit_inode_child(d,i,p) do { ; } while (0) -#define audit_receive_filter(t,p,u,s,d,l) ({ -EOPNOTSUPP; }) #define auditsc_get_stamp(c,t,s) do { BUG(); } while (0) #define audit_get_loginuid(c) ({ -1; }) #define audit_ipc_perms(q,u,g,m,i) ({ 0; }) @@ -313,7 +308,6 @@ extern int audit_set_macxattr(const char #define audit_sockaddr(len, addr) ({ 0; }) #define audit_avc_path(dentry, mnt) ({ 0; }) #define audit_signal_info(s,t) do { ; } while (0) -#define audit_filter_user(cb,t) ({ 1; }) #define audit_ipc_context(i) do { ; } while (0) #define audit_set_macxattr(n) do { ; } while (0) #endif @@ -339,13 +333,11 @@ extern void audit_log_d_path(struct const char *prefix, struct dentry *dentry, struct vfsmount *vfsmnt); - /* Private API (for auditsc.c only) */ -extern void audit_send_reply(int pid, int seq, int type, - int done, int multi, - void *payload, int size); -extern void audit_log_lost(const char *message); -extern void audit_panic(const char *message); -extern struct semaphore audit_netlink_sem; + /* Private API (for audit.c only) */ +extern int audit_filter_user(struct netlink_skb_parms *cb, int type); +extern int audit_filter_exclude(int type); +extern int audit_receive_filter(int type, int pid, int uid, int seq, + void *data, uid_t loginuid); #else #define audit_log(c,g,t,f,...) do { ; } while (0) #define audit_log_start(c,g,t) ({ NULL; }) diff --git a/kernel/Makefile b/kernel/Makefile index 4f5a145..56f6189 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -23,7 +23,7 @@ obj-$(CONFIG_COMPAT) += compat.o obj-$(CONFIG_CPUSETS) += cpuset.o obj-$(CONFIG_IKCONFIG) += configs.o obj-$(CONFIG_STOP_MACHINE) += stop_machine.o -obj-$(CONFIG_AUDIT) += audit.o +obj-$(CONFIG_AUDIT) += audit.o auditfilter.o obj-$(CONFIG_AUDITSYSCALL) += auditsc.o obj-$(CONFIG_KPROBES) += kprobes.o obj-$(CONFIG_SYSFS) += ksysfs.o diff --git a/kernel/audit.c b/kernel/audit.c index 9c13bf6..5941a07 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -305,6 +305,7 @@ int kauditd_thread(void *dummy) remove_wait_queue(&kauditd_wait, &wait); } } + return 0; } /**

diff --git a/kernel/auditsc.c b/kernel/auditsc.c index 3e46e1c..8f0a61c 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -51,17 +51,15 @@ #include <linux/audit.h> #include <linux/personality.h> #include <linux/time.h> -#include <linux/kthread.h> #include <linux/netlink.h> #include <linux/compiler.h> #include <asm/unistd.h> #include <linux/security.h> +#include <linux/list.h> -/* 0 = no checking - 1 = put_count checking - 2 = verbose put_count checking -*/ -#define AUDIT_DEBUG 0 +#include "audit.h" + +extern struct list_head audit_filter_list[]; /* No syscall auditing will take place unless audit_enabled != 0. */ extern int audit_enabled; @@ -75,29 +73,6 @@ extern int audit_enabled; * path_lookup. */ #define AUDIT_NAMES_RESERVED 7 -/* At task start time, the audit_state is set in the audit_context using - a per-task filter. At syscall entry, the audit_state is augmented by - the syscall filter. */ -enum audit_state { - AUDIT_DISABLED, /* Do not create per-task audit_context. - * No syscall-specific audit records can - * be generated. */ - AUDIT_SETUP_CONTEXT, /* Create the per-task audit_context, - * but don't necessarily fill it in at - * syscall entry time (i.e., filter - * instead). */ - AUDIT_BUILD_CONTEXT, /* Create the per-task audit_context, - * and always fill it in at syscall - * entry time. This makes a full - * syscall record available if some - * other part of the kernel decides it - * should be recorded. */ - AUDIT_RECORD_CONTEXT /* Create the per-task audit_context, - * always fill it in at syscall entry - * time, and always write out the audit - * record at syscall exit time. */ -}; - /* When fs/namei.c:getname() is called, we store the pointer in name and * we don't let putname() free it (instead we free all of the saved * pointers at syscall exit time). @@ -182,264 +157,6 @@ struct audit_context { #endif }; - /* Public API */ -/* There are three lists of rules -- one to search at task creation - * time, one to search at syscall entry time, and another to search at - * syscall exit time. */ -static 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]), -#if AUDIT_NR_FILTERS != 6 -#error Fix audit_filter_list initialiser -#endif -}; - -struct audit_entry { - struct list_head list; - struct rcu_head rcu; - struct audit_rule rule; -}; - -extern int audit_pid; - -/* 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) -{ - 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]; - } - for (i = 0; i < AUDIT_BITMASK_SIZE; i++) d->mask[i] = s->mask[i]; - return 0; -} - -/* 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 inline int audit_compare_rule(struct audit_rule *a, struct audit_rule *b) -{ - int i; - - if (a->flags != b->flags) - return 1; - - if (a->action != b->action) - return 1; - - if (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]) - return 1; - } - - for (i = 0; i < AUDIT_BITMASK_SIZE; i++) - if (a->mask[i] != b->mask[i]) - return 1; - - return 0; -} - -/* Note that audit_add_rule and audit_del_rule are called via - * audit_receive() in audit.c, and are protected by - * audit_netlink_sem. */ -static inline int audit_add_rule(struct audit_rule *rule, - struct list_head *list) -{ - struct audit_entry *entry; - int i; - - /* 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)) { - 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); - } - - 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 - * audit_netlink_sem. */ -static inline int audit_del_rule(struct audit_rule *rule, - struct list_head *list) -{ - struct audit_entry *e; - - /* 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)) { - list_del_rcu(&e->list); - call_rcu(&e->rcu, audit_free_rule); - return 0; - } - } - return -ENOENT; /* No matching rule */ -} - -static int audit_list_rules(void *_dest) -{ - int pid, seq; - int *dest = _dest; - struct audit_entry *entry; - 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; i<AUDIT_NR_FILTERS; i++) { - list_for_each_entry(entry, &audit_filter_list[i], list) - audit_send_reply(pid, seq, AUDIT_LIST, 0, 1, - &entry->rule, sizeof(entry->rule)); - } - audit_send_reply(pid, seq, AUDIT_LIST, 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 - * @pid: target pid for netlink audit messages - * @uid: target uid for netlink audit messages - * @seq: netlink audit message sequence (serial) number - * @data: payload data - * @loginuid: loginuid of sender - */ -int audit_receive_filter(int type, int pid, int uid, int seq, void *data, - uid_t loginuid) -{ - struct task_struct *tsk; - int *dest; - int err = 0; - unsigned listnr; - - switch (type) { - case AUDIT_LIST: - /* 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(2 * sizeof(int), GFP_KERNEL); - if (!dest) - return -ENOMEM; - dest[0] = pid; - dest[1] = seq; - - 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; - if (listnr >= AUDIT_NR_FILTERS) - return -EINVAL; - - err = audit_add_rule(data, &audit_filter_list[listnr]); - if (!err) - audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE, - "auid=%u added an audit rule\n", loginuid); - 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]); - if (!err) - audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE, - "auid=%u removed an audit rule\n", loginuid); - break; - default: - return -EINVAL; - } - - return err; -} - -static int audit_comparator(const u32 left, const u32 op, const u32 right) -{ - switch (op) { - case AUDIT_EQUAL: - return (left == right); - case AUDIT_NOT_EQUAL: - return (left != right); - case AUDIT_LESS_THAN: - return (left < right); - case AUDIT_LESS_THAN_OR_EQUAL: - return (left <= right); - case AUDIT_GREATER_THAN: - return (left > right); - case AUDIT_GREATER_THAN_OR_EQUAL: - return (left >= right); - default: - return -EINVAL; - } -} /* Compare a task_struct with an audit_rule. Return 1 on match, 0 * otherwise. */ @@ -612,95 +329,6 @@ static enum audit_state audit_filter_sys return AUDIT_BUILD_CONTEXT; } -static int audit_filter_user_rules(struct netlink_skb_parms *cb, - struct audit_rule *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]; - int result = 0; - - switch (field) { - case AUDIT_PID: - result = audit_comparator(cb->creds.pid, op, value); - break; - case AUDIT_UID: - result = audit_comparator(cb->creds.uid, op, value); - break; - case AUDIT_GID: - result = audit_comparator(cb->creds.gid, op, value); - break; - case AUDIT_LOGINUID: - result = audit_comparator(cb->loginuid, op, value); - break; - } - - if (!result) - return 0; - } - switch (rule->action) { - case AUDIT_NEVER: *state = AUDIT_DISABLED; break; - case AUDIT_POSSIBLE: *state = AUDIT_BUILD_CONTEXT; break; - case AUDIT_ALWAYS: *state = AUDIT_RECORD_CONTEXT; break; - } - return 1; -} - -int audit_filter_user(struct netlink_skb_parms *cb, int type) -{ - struct audit_entry *e; - enum audit_state state; - int ret = 1; - - rcu_read_lock(); - list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_USER], list) { - if (audit_filter_user_rules(cb, &e->rule, &state)) { - if (state == AUDIT_DISABLED) - ret = 0; - break; - } - } - rcu_read_unlock(); - - return ret; /* Audit by default */ -} - -int audit_filter_exclude(int type) -{ - struct audit_entry *e; - int result = 0; - - rcu_read_lock(); - if (list_empty(&audit_filter_list[AUDIT_FILTER_EXCLUDE])) - goto unlock_and_return; - - list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_EXCLUDE], - 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); - if (!result) - break; - } - } - if (result) - goto unlock_and_return; - } -unlock_and_return: - rcu_read_unlock(); - return result; -} - - /* This should be called with task_lock() held. */ static inline struct audit_context *audit_get_context(struct task_struct *tsk, int return_valid, -- dwmw2 -- Linux-audit mailing list Linux-audit(a)redhat.com https://www.redhat.com/mailman/listinfo/linux-audit