Commit 7e5cb5e1 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'vfs-cleanups' (random vfs cleanups) 

This teaches vfs_fstat() to use the appropriate f[get|put]_light
functions, allowing it to avoid some unnecessary locking for the common
case.

More noticeably, it also cleans up and simplifies the "getname_flags()"
function, which now relies on the architecture strncpy_from_user() doing
all the user access checks properly, instead of hacking around the fact
that on x86 it didn't use to do it right (see commit 92ae03f2: "x86:
merge 32/64-bit versions of 'strncpy_from_user()' and speed it up").

* vfs-cleanups:
  VFS: make vfs_fstat() use f[get|put]_light()
  VFS: clean up and simplify getname_flags()
  x86: make word-at-a-time strncpy_from_user clear bytes at the end
parents 8c12fec9 e994defb

arch/x86/lib/usercopy.c

+8 −12
Original line number Diff line number Diff line
@@ -44,13 +44,6 @@ copy_from_user_nmi(void *to, const void __user *from, unsigned long n) 
}

EXPORT_SYMBOL_GPL(copy_from_user_nmi);



static inline unsigned long count_bytes(unsigned long mask)

{

	mask = (mask - 1) & ~mask;

	mask >>= 7;

	return count_masked_bytes(mask);

}



/*

 * Do a strncpy, return length of string without final '\0'.

 * 'count' is the user-supplied count (return 'count' if we
@@ -69,16 +62,19 @@ static inline long do_strncpy_from_user(char *dst, const char __user *src, long 
		max = count;



	while (max >= sizeof(unsigned long)) {

		unsigned long c;

		unsigned long c, mask;



		/* Fall back to byte-at-a-time if we get a page fault */

		if (unlikely(__get_user(c,(unsigned long __user *)(src+res))))

			break;

		/* This can write a few bytes past the NUL character, but that's ok */

		mask = has_zero(c);

		if (mask) {

			mask = (mask - 1) & ~mask;

			mask >>= 7;

			*(unsigned long *)(dst+res) = c & mask;

			return res + count_masked_bytes(mask);

		}

		*(unsigned long *)(dst+res) = c;

		c = has_zero(c);

		if (c)

			return res + count_bytes(c);

		res += sizeof(unsigned long);

		max -= sizeof(unsigned long);

	}

fs/namei.c

+24 −34
Original line number Diff line number Diff line
@@ -116,49 +116,39 @@ 
 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).

 * PATH_MAX includes the nul terminator --RR.

 */

static int do_getname(const char __user *filename, char *page)

{

	int retval;

	unsigned long len = PATH_MAX;



	if (!segment_eq(get_fs(), KERNEL_DS)) {

		if ((unsigned long) filename >= TASK_SIZE)

			return -EFAULT;

		if (TASK_SIZE - (unsigned long) filename < PATH_MAX)

			len = TASK_SIZE - (unsigned long) filename;

	}



	retval = strncpy_from_user(page, filename, len);

	if (retval > 0) {

		if (retval < len)

			return 0;

		return -ENAMETOOLONG;

	} else if (!retval)

		retval = -ENOENT;

	return retval;

}



static char *getname_flags(const char __user *filename, int flags, int *empty)

{

	char *result = __getname();

	int retval;

	char *result = __getname(), *err;

	int len;



	if (!result)

	if (unlikely(!result))

		return ERR_PTR(-ENOMEM);



	retval = do_getname(filename, result);

	if (retval < 0) {

		if (retval == -ENOENT && empty)

	len = strncpy_from_user(result, filename, PATH_MAX);

	err = ERR_PTR(len);

	if (unlikely(len < 0))

		goto error;



	/* The empty path is special. */

	if (unlikely(!len)) {

		if (empty)

			*empty = 1;

		if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) {

			__putname(result);

			return ERR_PTR(retval);

		}

		err = ERR_PTR(-ENOENT);

		if (!(flags & LOOKUP_EMPTY))

			goto error;

	}



	err = ERR_PTR(-ENAMETOOLONG);

	if (likely(len < PATH_MAX)) {

		audit_getname(result);

		return result;

	}



error:

	__putname(result);

	return err;

}



char *getname(const char __user * filename)

{

	return getname_flags(filename, 0, NULL);

fs/stat.c

+3 −2
Original line number Diff line number Diff line
@@ -57,12 +57,13 @@ EXPORT_SYMBOL(vfs_getattr); 


int vfs_fstat(unsigned int fd, struct kstat *stat)

{

	struct file *f = fget(fd);

	int fput_needed;

	struct file *f = fget_light(fd, &fput_needed);

	int error = -EBADF;



	if (f) {

		error = vfs_getattr(f->f_path.mnt, f->f_path.dentry, stat);

		fput(f);

		fput_light(f, fput_needed);

	}

	return error;

}

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