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audit: replace getname()/putname() hacks with reference counters

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In order to ensure that filenames are not released before the audit
subsystem is done with the strings there are a number of hacks built
into the fs and audit subsystems around getname() and putname().  To
say these hacks are "ugly" would be kind.

This patch removes the filename hackery in favor of a more
conventional reference count based approach.  The diffstat below tells
most of the story; lots of audit/fs specific code is replaced with a
traditional reference count based approach that is easily understood,
even by those not familiar with the audit and/or fs subsystems.

CC: viro@zeniv.linux.org.uk
CC: linux-fsdevel@vger.kernel.org
Signed-off-by: Paul Moore <pmoore@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Paul Moore
2015-01-22 00:00:23 -05:00
committed by Al Viro
parent 57c59f5837
commit 55422d0bd2
5 changed files with 29 additions and 134 deletions
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105
kernel/auditsc.c
View File

@@ -866,33 +866,10 @@ static inline void audit_free_names(struct audit_context *context)
{
struct audit_names *n, *next;
#if AUDIT_DEBUG == 2
if (context->put_count + context->ino_count != context->name_count) {
int i = 0;
pr_err("%s:%d(:%d): major=%d in_syscall=%d"
" name_count=%d put_count=%d ino_count=%d"
" [NOT freeing]\n", __FILE__, __LINE__,
context->serial, context->major, context->in_syscall,
context->name_count, context->put_count,
context->ino_count);
list_for_each_entry(n, &context->names_list, list) {
pr_err("names[%d] = %p = %s\n", i++, n->name,
n->name->name ?: "(null)");
}
dump_stack();
return;
}
#endif
#if AUDIT_DEBUG
context->put_count = 0;
context->ino_count = 0;
#endif
list_for_each_entry_safe(n, next, &context->names_list, list) {
list_del(&n->list);
if (n->name && n->name_put)
final_putname(n->name);
if (n->name)
putname(n->name);
if (n->should_free)
kfree(n);
}
@@ -1711,9 +1688,6 @@ static struct audit_names *audit_alloc_name(struct audit_context *context,
list_add_tail(&aname->list, &context->names_list);
context->name_count++;
#if AUDIT_DEBUG
context->ino_count++;
#endif
return aname;
}
@@ -1734,8 +1708,10 @@ __audit_reusename(const __user char *uptr)
list_for_each_entry(n, &context->names_list, list) {
if (!n->name)
continue;
if (n->name->uptr == uptr)
if (n->name->uptr == uptr) {
n->name->refcnt++;
return n->name;
}
}
return NULL;
}
@@ -1752,19 +1728,8 @@ void __audit_getname(struct filename *name)
struct audit_context *context = current->audit_context;
struct audit_names *n;
if (!context->in_syscall) {
#if AUDIT_DEBUG == 2
pr_err("%s:%d(:%d): ignoring getname(%p)\n",
__FILE__, __LINE__, context->serial, name);
dump_stack();
#endif
if (!context->in_syscall)
return;
}
#if AUDIT_DEBUG
/* The filename _must_ have a populated ->name */
BUG_ON(!name->name);
#endif
n = audit_alloc_name(context, AUDIT_TYPE_UNKNOWN);
if (!n)
@@ -1772,56 +1737,13 @@ void __audit_getname(struct filename *name)
n->name = name;
n->name_len = AUDIT_NAME_FULL;
n->name_put = true;
name->aname = n;
name->refcnt++;
if (!context->pwd.dentry)
get_fs_pwd(current->fs, &context->pwd);
}
/* audit_putname - intercept a putname request
* @name: name to intercept and delay for putname
*
* If we have stored the name from getname in the audit context,
* then we delay the putname until syscall exit.
* Called from include/linux/fs.h:putname().
*/
void audit_putname(struct filename *name)
{
struct audit_context *context = current->audit_context;
BUG_ON(!context);
if (!name->aname || !context->in_syscall) {
#if AUDIT_DEBUG == 2
pr_err("%s:%d(:%d): final_putname(%p)\n",
__FILE__, __LINE__, context->serial, name);
if (context->name_count) {
struct audit_names *n;
int i = 0;
list_for_each_entry(n, &context->names_list, list)
pr_err("name[%d] = %p = %s\n", i++, n->name,
n->name->name ?: "(null)");
}
#endif
final_putname(name);
}
#if AUDIT_DEBUG
else {
++context->put_count;
if (context->put_count > context->name_count) {
pr_err("%s:%d(:%d): major=%d in_syscall=%d putname(%p)"
" name_count=%d put_count=%d\n",
__FILE__, __LINE__,
context->serial, context->major,
context->in_syscall, name->name,
context->name_count, context->put_count);
dump_stack();
}
}
#endif
}
/**
* __audit_inode - store the inode and device from a lookup
* @name: name being audited
@@ -1842,11 +1764,6 @@ void __audit_inode(struct filename *name, const struct dentry *dentry,
if (!name)
goto out_alloc;
#if AUDIT_DEBUG
/* The struct filename _must_ have a populated ->name */
BUG_ON(!name->name);
#endif
/*
* If we have a pointer to an audit_names entry already, then we can
* just use it directly if the type is correct.
@@ -1893,9 +1810,10 @@ out_alloc:
n = audit_alloc_name(context, AUDIT_TYPE_UNKNOWN);
if (!n)
return;
if (name)
/* no need to set ->name_put as the original will cleanup */
if (name) {
n->name = name;
name->refcnt++;
}
out:
if (parent) {
@@ -2000,8 +1918,7 @@ void __audit_inode_child(const struct inode *parent,
if (found_parent) {
found_child->name = found_parent->name;
found_child->name_len = AUDIT_NAME_FULL;
/* don't call __putname() */
found_child->name_put = false;
found_child->name->refcnt++;
}
}