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authorLinus Torvalds <torvalds@linux-foundation.org>2012-05-21 08:46:08 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-05-21 08:46:08 -0700
commit7e5cb5e151c5474b4a468f437f5038ba9f67ef4d (patch)
tree899f42e88f926fb4501402cf4ee4aa0903421ef5
parent8c12fec90c54cfabdd57b2726a1defbc07c19a55 (diff)
parente994defb7b6813ba6fa7a2a36e86d2455ad1dc35 (diff)
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
-rw-r--r--arch/x86/lib/usercopy.c20
-rw-r--r--fs/namei.c58
-rw-r--r--fs/stat.c5
3 files changed, 35 insertions, 48 deletions
diff --git a/arch/x86/lib/usercopy.c b/arch/x86/lib/usercopy.c
index d6ae30bbd7b..2e4e4b02c37 100644
--- a/arch/x86/lib/usercopy.c
+++ b/arch/x86/lib/usercopy.c
@@ -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);
}
diff --git a/fs/namei.c b/fs/namei.c
index c42791914f8..709fb2c17b5 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -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)
diff --git a/fs/stat.c b/fs/stat.c
index b30ac60291e..0cef3366a91 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -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;
}