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 92ae03f2ef99: "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
This commit is contained in:
Linus Torvalds 2012-05-21 08:46:08 -07:00
Родитель 8c12fec90c e994defb7b
Коммит 7e5cb5e151
3 изменённых файлов: 35 добавлений и 48 удалений

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@ -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);
}

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@ -116,47 +116,37 @@
* 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;
}
audit_getname(result);
return result;
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)

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@ -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;
}