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Subject[PATCH 17/24] compat_ioctl: simplify the implementation
Date
Now that both native and compat ioctl syscalls are
in the same file, a couple of simplifications can
be made, bringing the implementation closer together:

- do_vfs_ioctl(), ioctl_preallocate(), and compat_ioctl_preallocate()
can become static, allowing the compiler to optimize better

- slightly update the coding style for consistency between
the functions.

- rather than listing each command in two switch statements
for the compat case, just call a single function that has
all the common commands.

As a side-effect, FS_IOC_RESVSP/FS_IOC_RESVSP64 are now available
to x86 compat tasks, along with FS_IOC_RESVSP_32/FS_IOC_RESVSP64_32.
This is harmless for i386 emulation, and can be considered a bugfix
for x32 emulation, which never supported these in the past.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
fs/internal.h | 6 --
fs/ioctl.c | 157 +++++++++++++++++------------------------
include/linux/falloc.h | 2 -
include/linux/fs.h | 4 --
4 files changed, 64 insertions(+), 105 deletions(-)

diff --git a/fs/internal.h b/fs/internal.h
index 4a7da1df573d..d46247850ad7 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -180,11 +180,5 @@ extern void mnt_pin_kill(struct mount *m);
*/
extern const struct dentry_operations ns_dentry_operations;

-/*
- * fs/ioctl.c
- */
-extern int do_vfs_ioctl(struct file *file, unsigned int fd, unsigned int cmd,
- unsigned long arg);
-
/* direct-io.c: */
int sb_init_dio_done_wq(struct super_block *sb);
diff --git a/fs/ioctl.c b/fs/ioctl.c
index 8f22f7817edb..7c9a5df5a597 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -467,7 +467,7 @@ EXPORT_SYMBOL(generic_block_fiemap);
* Only the l_start, l_len and l_whence fields of the 'struct space_resv'
* are used here, rest are ignored.
*/
-int ioctl_preallocate(struct file *filp, int mode, void __user *argp)
+static int ioctl_preallocate(struct file *filp, int mode, void __user *argp)
{
struct inode *inode = file_inode(filp);
struct space_resv sr;
@@ -495,8 +495,8 @@ int ioctl_preallocate(struct file *filp, int mode, void __user *argp)
/* on ia32 l_start is on a 32-bit boundary */
#if defined CONFIG_COMPAT && defined(CONFIG_X86_64)
/* just account for different alignment */
-int compat_ioctl_preallocate(struct file *file, int mode,
- struct space_resv_32 __user *argp)
+static int compat_ioctl_preallocate(struct file *file, int mode,
+ struct space_resv_32 __user *argp)
{
struct inode *inode = file_inode(file);
struct space_resv_32 sr;
@@ -521,11 +521,9 @@ int compat_ioctl_preallocate(struct file *file, int mode,
}
#endif

-static int file_ioctl(struct file *filp, unsigned int cmd,
- unsigned long arg)
+static int file_ioctl(struct file *filp, unsigned int cmd, int __user *p)
{
struct inode *inode = file_inode(filp);
- int __user *p = (int __user *)arg;

switch (cmd) {
case FIBMAP:
@@ -542,7 +540,7 @@ static int file_ioctl(struct file *filp, unsigned int cmd,
return ioctl_preallocate(filp, FALLOC_FL_ZERO_RANGE, p);
}

- return vfs_ioctl(filp, cmd, arg);
+ return -ENOIOCTLCMD;
}

static int ioctl_fionbio(struct file *filp, int __user *argp)
@@ -661,53 +659,48 @@ static int ioctl_file_dedupe_range(struct file *file,
}

/*
- * When you add any new common ioctls to the switches above and below
- * please update compat_sys_ioctl() too.
- *
* do_vfs_ioctl() is not for drivers and not intended to be EXPORT_SYMBOL()'d.
* It's just a simple helper for sys_ioctl and compat_sys_ioctl.
+ *
+ * When you add any new common ioctls to the switches above and below,
+ * please ensure they have compatible arguments in compat mode.
*/
-int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd,
- unsigned long arg)
+static int do_vfs_ioctl(struct file *filp, unsigned int fd,
+ unsigned int cmd, unsigned long arg)
{
- int error = 0;
void __user *argp = (void __user *)arg;
struct inode *inode = file_inode(filp);

switch (cmd) {
case FIOCLEX:
set_close_on_exec(fd, 1);
- break;
+ return 0;

case FIONCLEX:
set_close_on_exec(fd, 0);
- break;
+ return 0;

case FIONBIO:
- error = ioctl_fionbio(filp, argp);
- break;
+ return ioctl_fionbio(filp, argp);

case FIOASYNC:
- error = ioctl_fioasync(fd, filp, argp);
- break;
+ return ioctl_fioasync(fd, filp, argp);

case FIOQSIZE:
if (S_ISDIR(inode->i_mode) || S_ISREG(inode->i_mode) ||
S_ISLNK(inode->i_mode)) {
loff_t res = inode_get_bytes(inode);
- error = copy_to_user(argp, &res, sizeof(res)) ?
- -EFAULT : 0;
- } else
- error = -ENOTTY;
- break;
+ return copy_to_user(argp, &res, sizeof(res)) ?
+ -EFAULT : 0;
+ }
+
+ return -ENOTTY;

case FIFREEZE:
- error = ioctl_fsfreeze(filp);
- break;
+ return ioctl_fsfreeze(filp);

case FITHAW:
- error = ioctl_fsthaw(filp);
- break;
+ return ioctl_fsthaw(filp);

case FS_IOC_FIEMAP:
return ioctl_fiemap(filp, argp);
@@ -716,6 +709,7 @@ int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd,
/* anon_bdev filesystems may not have a block size */
if (!inode->i_sb->s_blocksize)
return -EINVAL;
+
return put_user(inode->i_sb->s_blocksize, (int __user *)argp);

case FICLONE:
@@ -729,24 +723,30 @@ int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd,

default:
if (S_ISREG(inode->i_mode))
- error = file_ioctl(filp, cmd, arg);
- else
- error = vfs_ioctl(filp, cmd, arg);
+ return file_ioctl(filp, cmd, argp);
break;
}
- return error;
+
+ return -ENOIOCTLCMD;
}

int ksys_ioctl(unsigned int fd, unsigned int cmd, unsigned long arg)
{
- int error;
struct fd f = fdget(fd);
+ int error;

if (!f.file)
return -EBADF;
+
error = security_file_ioctl(f.file, cmd, arg);
- if (!error)
- error = do_vfs_ioctl(f.file, fd, cmd, arg);
+ if (error)
+ goto out;
+
+ error = do_vfs_ioctl(f.file, fd, cmd, arg);
+ if (error == -ENOIOCTLCMD)
+ error = vfs_ioctl(f.file, cmd, arg);
+
+out:
fdput(f);
return error;
}
@@ -790,92 +790,63 @@ long compat_ptr_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
EXPORT_SYMBOL(compat_ptr_ioctl);

COMPAT_SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd,
- compat_ulong_t, arg32)
+ compat_ulong_t, arg)
{
- unsigned long arg = arg32;
struct fd f = fdget(fd);
- int error = -EBADF;
+ int error;
+
if (!f.file)
- goto out;
+ return -EBADF;

/* RED-PEN how should LSM module know it's handling 32bit? */
error = security_file_ioctl(f.file, cmd, arg);
if (error)
- goto out_fput;
+ goto out;

switch (cmd) {
- /* these are never seen by ->ioctl(), no argument or int argument */
- case FIOCLEX:
- case FIONCLEX:
- case FIFREEZE:
- case FITHAW:
+ /* FICLONE takes an int argument, so don't use compat_ptr() */
case FICLONE:
- goto do_ioctl;
- /* these are never seen by ->ioctl(), pointer argument */
- case FIONBIO:
- case FIOASYNC:
- case FIOQSIZE:
- case FS_IOC_FIEMAP:
- case FIGETBSZ:
- case FICLONERANGE:
- case FIDEDUPERANGE:
- goto found_handler;
- /*
- * The next group is the stuff handled inside file_ioctl().
- * For regular files these never reach ->ioctl(); for
- * devices, sockets, etc. they do and one (FIONREAD) is
- * even accepted in some cases. In all those cases
- * argument has the same type, so we can handle these
- * here, shunting them towards do_vfs_ioctl().
- * ->compat_ioctl() will never see any of those.
- */
- /* pointer argument, never actually handled by ->ioctl() */
- case FIBMAP:
- goto found_handler;
- /* handled by some ->ioctl(); always a pointer to int */
- case FIONREAD:
- goto found_handler;
- /* these get messy on amd64 due to alignment differences */
+ error = ioctl_file_clone(f.file, arg, 0, 0, 0);
+ break;
+
#if defined(CONFIG_X86_64)
+ /* these get messy on amd64 due to alignment differences */
case FS_IOC_RESVSP_32:
case FS_IOC_RESVSP64_32:
error = compat_ioctl_preallocate(f.file, 0, compat_ptr(arg));
- goto out_fput;
+ break;
case FS_IOC_UNRESVSP_32:
case FS_IOC_UNRESVSP64_32:
error = compat_ioctl_preallocate(f.file, FALLOC_FL_PUNCH_HOLE,
compat_ptr(arg));
- goto out_fput;
+ break;
case FS_IOC_ZERO_RANGE_32:
error = compat_ioctl_preallocate(f.file, FALLOC_FL_ZERO_RANGE,
compat_ptr(arg));
- goto out_fput;
-#else
- case FS_IOC_RESVSP:
- case FS_IOC_RESVSP64:
- case FS_IOC_UNRESVSP:
- case FS_IOC_UNRESVSP64:
- case FS_IOC_ZERO_RANGE:
- goto found_handler;
+ break;
#endif

+ /*
+ * everything else in do_vfs_ioctl() takes either a compatible
+ * pointer argument or no argument -- call it with a modified
+ * argument.
+ */
default:
- if (f.file->f_op->compat_ioctl) {
+ error = do_vfs_ioctl(f.file, fd, cmd,
+ (unsigned long)compat_ptr(arg));
+ if (error != -ENOIOCTLCMD)
+ break;
+
+ if (f.file->f_op->compat_ioctl)
error = f.file->f_op->compat_ioctl(f.file, cmd, arg);
- if (error != -ENOIOCTLCMD)
- goto out_fput;
- }
- error = -ENOTTY;
- goto out_fput;
+ if (error == -ENOIOCTLCMD)
+ error = -ENOTTY;
+ break;
}

- found_handler:
- arg = (unsigned long)compat_ptr(arg);
- do_ioctl:
- error = do_vfs_ioctl(f.file, fd, cmd, arg);
- out_fput:
- fdput(f);
out:
+ fdput(f);
+
return error;
}
#endif
diff --git a/include/linux/falloc.h b/include/linux/falloc.h
index 8bf3d79f3e82..f3f0b97b1675 100644
--- a/include/linux/falloc.h
+++ b/include/linux/falloc.h
@@ -51,8 +51,6 @@ struct space_resv_32 {
#define FS_IOC_UNRESVSP64_32 _IOW ('X', 43, struct space_resv_32)
#define FS_IOC_ZERO_RANGE_32 _IOW ('X', 57, struct space_resv_32)

-int compat_ioctl_preallocate(struct file *, int, struct space_resv_32 __user *);
-
#endif

#endif /* _FALLOC_H_ */
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 98e0349adb52..daf570bca42a 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2552,10 +2552,6 @@ extern int finish_open(struct file *file, struct dentry *dentry,
int (*open)(struct inode *, struct file *));
extern int finish_no_open(struct file *file, struct dentry *dentry);

-/* fs/ioctl.c */
-
-extern int ioctl_preallocate(struct file *filp, int mode, void __user *argp);
-
/* fs/dcache.c */
extern void __init vfs_caches_init_early(void);
extern void __init vfs_caches_init(void);
--
2.20.0
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