[v2,20/27] compat_ioctl: simplify the implementation
diff mbox series

Message ID 20191217221708.3730997-21-arnd@arndb.de
State New
Headers show
Series
  • [v2,01/27] pktcdvd: fix regression on 64-bit architectures
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Commit Message

Arnd Bergmann Dec. 17, 2019, 10:17 p.m. UTC
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(-)

Comments

youling 257 Feb. 7, 2020, 7:22 a.m. UTC | #1
This patch cause a problem on 64bit kernel 32bit userspace.
My 32bit Androidx86 userspace run on 64bit mainline kernel, this patch caused some app not detect root permission.
Arnd Bergmann Feb. 7, 2020, 5:06 p.m. UTC | #2
On Fri, Feb 7, 2020 at 8:22 AM youling257 <youling257@gmail.com> wrote:
>
> This patch cause a problem on 64bit kernel 32bit userspace.
> My 32bit Androidx86 userspace run on 64bit mainline kernel, this patch caused some app not detect root permission.

Thanks for you work in bisecting the issue to my patch, sorry to have
caused you trouble. After Christian Zigotzky
also reported a problem in this file, I have been able to find a
specific bug and just submitted a patch for it.

Please have a look if that fix addresses your problem, as it's
possible that there was more than one bug introduced
by the original patch.

       Arnd
youling 257 Feb. 7, 2020, 8:02 p.m. UTC | #3
Test [PATCH] compat_ioctl: fix FIONREAD on devices, fixed my problem.

2020-02-08 1:06 GMT+08:00, Arnd Bergmann <arnd@arndb.de>:
> On Fri, Feb 7, 2020 at 8:22 AM youling257 <youling257@gmail.com> wrote:
>>
>> This patch cause a problem on 64bit kernel 32bit userspace.
>> My 32bit Androidx86 userspace run on 64bit mainline kernel, this patch
>> caused some app not detect root permission.
>
> Thanks for you work in bisecting the issue to my patch, sorry to have
> caused you trouble. After Christian Zigotzky
> also reported a problem in this file, I have been able to find a
> specific bug and just submitted a patch for it.
>
> Please have a look if that fix addresses your problem, as it's
> possible that there was more than one bug introduced
> by the original patch.
>
>        Arnd
>

Patch
diff mbox series

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);