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 92ae03f2ef
: "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:
commit
7e5cb5e151
3 changed files with 35 additions and 48 deletions
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@ -44,13 +44,6 @@ copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
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}
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EXPORT_SYMBOL_GPL(copy_from_user_nmi);
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static inline unsigned long count_bytes(unsigned long mask)
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{
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mask = (mask - 1) & ~mask;
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mask >>= 7;
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return count_masked_bytes(mask);
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}
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/*
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* Do a strncpy, return length of string without final '\0'.
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* 'count' is the user-supplied count (return 'count' if we
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@ -69,16 +62,19 @@ static inline long do_strncpy_from_user(char *dst, const char __user *src, long
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max = count;
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while (max >= sizeof(unsigned long)) {
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unsigned long c;
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unsigned long c, mask;
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/* Fall back to byte-at-a-time if we get a page fault */
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if (unlikely(__get_user(c,(unsigned long __user *)(src+res))))
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break;
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/* This can write a few bytes past the NUL character, but that's ok */
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mask = has_zero(c);
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if (mask) {
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mask = (mask - 1) & ~mask;
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mask >>= 7;
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*(unsigned long *)(dst+res) = c & mask;
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return res + count_masked_bytes(mask);
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}
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*(unsigned long *)(dst+res) = c;
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c = has_zero(c);
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if (c)
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return res + count_bytes(c);
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res += sizeof(unsigned long);
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max -= sizeof(unsigned long);
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}
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58
fs/namei.c
58
fs/namei.c
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@ -116,47 +116,37 @@
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* POSIX.1 2.4: an empty pathname is invalid (ENOENT).
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* PATH_MAX includes the nul terminator --RR.
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*/
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static int do_getname(const char __user *filename, char *page)
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{
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int retval;
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unsigned long len = PATH_MAX;
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if (!segment_eq(get_fs(), KERNEL_DS)) {
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if ((unsigned long) filename >= TASK_SIZE)
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return -EFAULT;
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if (TASK_SIZE - (unsigned long) filename < PATH_MAX)
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len = TASK_SIZE - (unsigned long) filename;
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}
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retval = strncpy_from_user(page, filename, len);
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if (retval > 0) {
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if (retval < len)
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return 0;
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return -ENAMETOOLONG;
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} else if (!retval)
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retval = -ENOENT;
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return retval;
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}
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static char *getname_flags(const char __user *filename, int flags, int *empty)
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{
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char *result = __getname();
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int retval;
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char *result = __getname(), *err;
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int len;
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if (!result)
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if (unlikely(!result))
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return ERR_PTR(-ENOMEM);
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retval = do_getname(filename, result);
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if (retval < 0) {
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if (retval == -ENOENT && empty)
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len = strncpy_from_user(result, filename, PATH_MAX);
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err = ERR_PTR(len);
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if (unlikely(len < 0))
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goto error;
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/* The empty path is special. */
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if (unlikely(!len)) {
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if (empty)
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*empty = 1;
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if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) {
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__putname(result);
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return ERR_PTR(retval);
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}
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err = ERR_PTR(-ENOENT);
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if (!(flags & LOOKUP_EMPTY))
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goto error;
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}
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audit_getname(result);
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return result;
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err = ERR_PTR(-ENAMETOOLONG);
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if (likely(len < PATH_MAX)) {
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audit_getname(result);
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return result;
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}
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error:
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__putname(result);
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return err;
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}
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char *getname(const char __user * filename)
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@ -57,12 +57,13 @@ EXPORT_SYMBOL(vfs_getattr);
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int vfs_fstat(unsigned int fd, struct kstat *stat)
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{
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struct file *f = fget(fd);
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int fput_needed;
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struct file *f = fget_light(fd, &fput_needed);
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int error = -EBADF;
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if (f) {
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error = vfs_getattr(f->f_path.mnt, f->f_path.dentry, stat);
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fput(f);
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fput_light(f, fput_needed);
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}
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return error;
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}
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