[PATCH 11/15] fixing audit rule ordering mess, part 1
Al Viro
viro at ftp.linux.org.uk
Wed Dec 17 05:12:50 UTC 2008
Problem: ordering between the rules on exit chain is currently lost;
all watch and inode rules are listed after everything else _and_
exit,never on one kind doesn't stop exit,always on another from
being matched.
Solution: assign priorities to rules, keep track of the current
highest-priority matching rule and its result (always/never).
Signed-off-by: Al Viro <viro at zeniv.linux.org.uk>
---
include/linux/audit.h | 1 +
kernel/audit.h | 5 +--
kernel/auditfilter.c | 17 +++++++++--
kernel/auditsc.c | 79 ++++++++++++++++++++++++++----------------------
4 files changed, 59 insertions(+), 43 deletions(-)
diff --git a/include/linux/audit.h b/include/linux/audit.h
index c5e95e7..d28682c 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -371,6 +371,7 @@ struct audit_krule {
struct audit_watch *watch; /* associated watch */
struct audit_tree *tree; /* associated watched tree */
struct list_head rlist; /* entry in audit_{watch,tree}.rules list */
+ u64 prio;
};
struct audit_field {
diff --git a/kernel/audit.h b/kernel/audit.h
index 9d67174..16f18ca 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -159,11 +159,8 @@ static inline int audit_signal_info(int sig, struct task_struct *t)
return __audit_signal_info(sig, t);
return 0;
}
-extern enum audit_state audit_filter_inodes(struct task_struct *,
- struct audit_context *);
-extern void audit_set_auditable(struct audit_context *);
+extern void audit_filter_inodes(struct task_struct *, struct audit_context *);
#else
#define audit_signal_info(s,t) AUDIT_DISABLED
#define audit_filter_inodes(t,c) AUDIT_DISABLED
-#define audit_set_auditable(c)
#endif
diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index 0febaa0..995a2e8 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -919,6 +919,7 @@ static struct audit_entry *audit_dupe_rule(struct audit_krule *old,
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->watch = NULL;
@@ -987,9 +988,8 @@ static void audit_update_watch(struct audit_parent *parent,
/* If the update involves invalidating rules, do the inode-based
* filtering now, so we don't omit records. */
- if (invalidating && current->audit_context &&
- audit_filter_inodes(current, current->audit_context) == AUDIT_RECORD_CONTEXT)
- audit_set_auditable(current->audit_context);
+ if (invalidating && current->audit_context)
+ audit_filter_inodes(current, current->audit_context);
nwatch = audit_dupe_watch(owatch);
if (IS_ERR(nwatch)) {
@@ -1258,6 +1258,9 @@ static int audit_add_watch(struct audit_krule *krule, struct nameidata *ndp,
return ret;
}
+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 list_head *list)
@@ -1319,6 +1322,14 @@ static inline int audit_add_rule(struct audit_entry *entry,
}
}
+ entry->rule.prio = ~0ULL;
+ if (entry->rule.listnr == AUDIT_FILTER_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_rcu(&entry->list, list);
entry->rule.flags &= ~AUDIT_FILTER_PREPEND;
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 5de0087..296d329 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -139,14 +139,14 @@ struct audit_tree_refs {
struct audit_context {
int dummy; /* must be the first element */
int in_syscall; /* 1 if task is in a syscall */
- enum audit_state state;
+ enum audit_state state, current_state;
unsigned int serial; /* serial number for record */
struct timespec ctime; /* time of syscall entry */
int major; /* syscall number */
unsigned long argv[4]; /* syscall arguments */
int return_valid; /* return code is valid */
long return_code;/* syscall return code */
- int auditable; /* 1 if record should be written */
+ u64 prio;
int name_count;
struct audit_names names[AUDIT_NAMES];
char * filterkey; /* key for rule that triggered record */
@@ -597,8 +597,16 @@ static int audit_filter_rules(struct task_struct *tsk,
if (!result)
return 0;
}
- if (rule->filterkey && ctx)
- ctx->filterkey = kstrdup(rule->filterkey, GFP_ATOMIC);
+
+ if (ctx) {
+ if (rule->prio <= ctx->prio)
+ return 0;
+ if (rule->filterkey) {
+ kfree(ctx->filterkey);
+ ctx->filterkey = kstrdup(rule->filterkey, GFP_ATOMIC);
+ }
+ ctx->prio = rule->prio;
+ }
switch (rule->action) {
case AUDIT_NEVER: *state = AUDIT_DISABLED; break;
case AUDIT_ALWAYS: *state = AUDIT_RECORD_CONTEXT; break;
@@ -651,6 +659,7 @@ static enum audit_state audit_filter_syscall(struct task_struct *tsk,
audit_filter_rules(tsk, &e->rule, ctx, NULL,
&state)) {
rcu_read_unlock();
+ ctx->current_state = state;
return state;
}
}
@@ -664,15 +673,14 @@ static enum audit_state audit_filter_syscall(struct task_struct *tsk,
* buckets applicable to the inode numbers in audit_names[].
* Regarding audit_state, same rules apply as for audit_filter_syscall().
*/
-enum audit_state audit_filter_inodes(struct task_struct *tsk,
- struct audit_context *ctx)
+void audit_filter_inodes(struct task_struct *tsk, struct audit_context *ctx)
{
int i;
struct audit_entry *e;
enum audit_state state;
if (audit_pid && tsk->tgid == audit_pid)
- return AUDIT_DISABLED;
+ return;
rcu_read_lock();
for (i = 0; i < ctx->name_count; i++) {
@@ -689,17 +697,20 @@ enum audit_state audit_filter_inodes(struct task_struct *tsk,
if ((e->rule.mask[word] & bit) == bit &&
audit_filter_rules(tsk, &e->rule, ctx, n, &state)) {
rcu_read_unlock();
- return state;
+ ctx->current_state = state;
+ return;
}
}
}
rcu_read_unlock();
- return AUDIT_BUILD_CONTEXT;
}
-void audit_set_auditable(struct audit_context *ctx)
+static void audit_set_auditable(struct audit_context *ctx)
{
- ctx->auditable = 1;
+ if (!ctx->prio) {
+ ctx->prio = 1;
+ ctx->current_state = AUDIT_RECORD_CONTEXT;
+ }
}
static inline struct audit_context *audit_get_context(struct task_struct *tsk,
@@ -730,23 +741,11 @@ static inline struct audit_context *audit_get_context(struct task_struct *tsk,
else
context->return_code = return_code;
- if (context->in_syscall && !context->dummy && !context->auditable) {
- enum audit_state state;
-
- state = audit_filter_syscall(tsk, context, &audit_filter_list[AUDIT_FILTER_EXIT]);
- if (state == AUDIT_RECORD_CONTEXT) {
- context->auditable = 1;
- goto get_context;
- }
-
- state = audit_filter_inodes(tsk, context);
- if (state == AUDIT_RECORD_CONTEXT)
- context->auditable = 1;
-
+ if (context->in_syscall && !context->dummy) {
+ audit_filter_syscall(tsk, context, &audit_filter_list[AUDIT_FILTER_EXIT]);
+ audit_filter_inodes(tsk, context);
}
-get_context:
-
tsk->audit_context = NULL;
return context;
}
@@ -756,8 +755,7 @@ static inline void audit_free_names(struct audit_context *context)
int i;
#if AUDIT_DEBUG == 2
- if (context->auditable
- ||context->put_count + context->ino_count != context->name_count) {
+ if (context->put_count + context->ino_count != context->name_count) {
printk(KERN_ERR "%s:%d(:%d): major=%d in_syscall=%d"
" name_count=%d put_count=%d"
" ino_count=%d [NOT freeing]\n",
@@ -808,6 +806,7 @@ static inline void audit_zero_context(struct audit_context *context,
{
memset(context, 0, sizeof(*context));
context->state = state;
+ context->prio = state == AUDIT_RECORD_CONTEXT ? ~0ULL : 0;
}
static inline struct audit_context *audit_alloc_context(enum audit_state state)
@@ -1456,7 +1455,7 @@ void audit_free(struct task_struct *tsk)
* We use GFP_ATOMIC here because we might be doing this
* in the context of the idle thread */
/* that can happen only if we are called from do_exit() */
- if (context->in_syscall && context->auditable)
+ if (context->in_syscall && context->current_state == AUDIT_RECORD_CONTEXT)
audit_log_exit(context, tsk);
audit_free_context(context);
@@ -1540,15 +1539,17 @@ void audit_syscall_entry(int arch, int major,
state = context->state;
context->dummy = !audit_n_rules;
- if (!context->dummy && (state == AUDIT_SETUP_CONTEXT || state == AUDIT_BUILD_CONTEXT))
+ if (!context->dummy && state == AUDIT_BUILD_CONTEXT) {
+ context->prio = 0;
state = audit_filter_syscall(tsk, context, &audit_filter_list[AUDIT_FILTER_ENTRY]);
+ }
if (likely(state == AUDIT_DISABLED))
return;
context->serial = 0;
context->ctime = CURRENT_TIME;
context->in_syscall = 1;
- context->auditable = !!(state == AUDIT_RECORD_CONTEXT);
+ context->current_state = state;
context->ppid = 0;
}
@@ -1556,17 +1557,20 @@ void audit_finish_fork(struct task_struct *child)
{
struct audit_context *ctx = current->audit_context;
struct audit_context *p = child->audit_context;
- if (!p || !ctx || !ctx->auditable)
+ if (!p || !ctx)
+ return;
+ if (!ctx->in_syscall || ctx->current_state != AUDIT_RECORD_CONTEXT)
return;
p->arch = ctx->arch;
p->major = ctx->major;
memcpy(p->argv, ctx->argv, sizeof(ctx->argv));
p->ctime = ctx->ctime;
p->dummy = ctx->dummy;
- p->auditable = ctx->auditable;
p->in_syscall = ctx->in_syscall;
p->filterkey = kstrdup(ctx->filterkey, GFP_KERNEL);
p->ppid = current->pid;
+ p->prio = ctx->prio;
+ p->current_state = ctx->current_state;
}
/**
@@ -1590,11 +1594,11 @@ void audit_syscall_exit(int valid, long return_code)
if (likely(!context))
return;
- if (context->in_syscall && context->auditable)
+ if (context->in_syscall && context->current_state == AUDIT_RECORD_CONTEXT)
audit_log_exit(context, tsk);
context->in_syscall = 0;
- context->auditable = 0;
+ context->prio = context->state == AUDIT_RECORD_CONTEXT ? ~0ULL : 0;
if (context->previous) {
struct audit_context *new_context = context->previous;
@@ -1975,7 +1979,10 @@ int auditsc_get_stamp(struct audit_context *ctx,
t->tv_sec = ctx->ctime.tv_sec;
t->tv_nsec = ctx->ctime.tv_nsec;
*serial = ctx->serial;
- ctx->auditable = 1;
+ if (!ctx->prio) {
+ ctx->prio = 1;
+ ctx->current_state = AUDIT_RECORD_CONTEXT;
+ }
return 1;
}
--
1.5.6.5
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