audit: replace getname()/putname() hacks with reference counters (55422d0b) · Commits · 戴 / test

fs/namei.c

+14 −15

Original line number	Diff line number	Diff line
		@@ -118,15 +118,6 @@
		* POSIX.1 2.4: an empty pathname is invalid (ENOENT).
		* PATH_MAX includes the nul terminator --RR.
		*/
		void final_putname(struct filename *name)
		{
		if (name->separate) {
		__putname(name->name);
		kfree(name);
		} else {
		__putname(name);
		}
		}

		#define EMBEDDED_NAME_MAX (PATH_MAX - sizeof(struct filename))

		@@ -145,6 +136,7 @@ getname_flags(const char __user filename, int flags, int empty)
		result = __getname();
		if (unlikely(!result))
		return ERR_PTR(-ENOMEM);
		result->refcnt = 1;

		/*
		* First, try to embed the struct filename inside the names_cache
		@@ -179,6 +171,7 @@ recopy:
		}
		result->name = kname;
		result->separate = true;
		result->refcnt = 1;
		max = PATH_MAX;
		goto recopy;
		}
		@@ -202,7 +195,7 @@ recopy:
		return result;

		error:
		final_putname(result);
		putname(result);
		return err;
		}

		@@ -243,19 +236,25 @@ getname_kernel(const char * filename)
		memcpy((char *)result->name, filename, len);
		result->uptr = NULL;
		result->aname = NULL;
		result->refcnt = 1;
		audit_getname(result);

		return result;
		}

		#ifdef CONFIG_AUDITSYSCALL
		void putname(struct filename *name)
		{
		if (unlikely(!audit_dummy_context()))
		return audit_putname(name);
		final_putname(name);
		BUG_ON(name->refcnt <= 0);

		if (--name->refcnt > 0)
		return;

		if (name->separate) {
		__putname(name->name);
		kfree(name);
		} else
		__putname(name);
		}
		#endif

		static int check_acl(struct inode *inode, int mask)
		{

include/linux/audit.h

+0 −3

Original line number	Diff line number	Diff line
		@@ -128,7 +128,6 @@ extern void __audit_syscall_entry(int major, unsigned long a0, unsigned long a1,
		extern void __audit_syscall_exit(int ret_success, long ret_value);
		extern struct filename __audit_reusename(const __user char uptr);
		extern void __audit_getname(struct filename *name);
		extern void audit_putname(struct filename *name);

		#define AUDIT_INODE_PARENT 1 /* dentry represents the parent */
		#define AUDIT_INODE_HIDDEN 2 /* audit record should be hidden */
		@@ -353,8 +352,6 @@ static inline struct filename audit_reusename(const __user char name)
		}
		static inline void audit_getname(struct filename *name)
		{ }
		static inline void audit_putname(struct filename *name)
		{ }
		static inline void __audit_inode(struct filename *name,
		const struct dentry *dentry,
		unsigned int flags)

include/linux/fs.h

+2 −7

Original line number	Diff line number	Diff line
		@@ -2080,6 +2080,7 @@ struct filename {
		const char name; / pointer to actual string */
		const __user char uptr; / original userland pointer */
		struct audit_names *aname;
		int refcnt;
		bool separate; /* should "name" be freed? */
		};

		@@ -2101,6 +2102,7 @@ extern int filp_close(struct file *, fl_owner_t id);
		extern struct filename getname_flags(const char __user , int, int *);
		extern struct filename getname(const char __user );
		extern struct filename getname_kernel(const char );
		extern void putname(struct filename *name);

		enum {
		FILE_CREATED = 1,
		@@ -2121,15 +2123,8 @@ extern void __init vfs_caches_init(unsigned long);

		extern struct kmem_cache *names_cachep;

		extern void final_putname(struct filename *name);

		#define __getname() kmem_cache_alloc(names_cachep, GFP_KERNEL)
		#define __putname(name) kmem_cache_free(names_cachep, (void *)(name))
		#ifndef CONFIG_AUDITSYSCALL
		#define putname(name) final_putname(name)
		#else
		extern void putname(struct filename *name);
		#endif

		#ifdef CONFIG_BLOCK
		extern int register_blkdev(unsigned int, const char *);

kernel/audit.h

+2 −15

Original line number	Diff line number	Diff line
		@@ -24,12 +24,6 @@
		#include <linux/skbuff.h>
		#include <uapi/linux/mqueue.h>

		/* 0 = no checking
		1 = put_count checking
		2 = verbose put_count checking
		*/
		#define AUDIT_DEBUG 0

		/* AUDIT_NAMES is the number of slots we reserve in the audit_context
		* for saving names from getname(). If we get more names we will allocate
		* a name dynamically and also add those to the list anchored by names_list. */
		@@ -74,9 +68,8 @@ struct audit_cap_data {
		};
		};

		/* 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).
		/* When fs/namei.c:getname() is called, we store the pointer in name and bump
		* the refcnt in the associated filename struct.
		*
		* Further, in fs/namei.c:path_lookup() we store the inode and device.
		*/
		@@ -86,7 +79,6 @@ struct audit_names {
		struct filename *name;
		int name_len; /* number of chars to log */
		bool hidden; /* don't log this record */
		bool name_put; /* call __putname()? */

		unsigned long ino;
		dev_t dev;
		@@ -208,11 +200,6 @@ struct audit_context {
		};
		int fds[2];
		struct audit_proctitle proctitle;

		#if AUDIT_DEBUG
		int put_count;
		int ino_count;
		#endif
		};

		extern u32 audit_ever_enabled;

kernel/auditsc.c

+11 −94

Original line number	Diff line number	Diff line
		@@ -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;
		}

		@@ -1734,9 +1708,11 @@ __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++;
		}
		}

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