vfs_masks_device_ioctl() and vfs_masks_device_ioctl_compat() are useful
to differenciate between device driver IOCTL implementations and
filesystem ones. The goal is to be able to filter well-defined IOCTLs
from per-device (i.e. namespaced) IOCTLs and control such access.
Add a new ioctl_compat() helper, similar to vfs_ioctl(), to wrap
compat_ioctl() calls and handle error conversions.
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
Cc: Günther Noack <gnoack@xxxxxxxxxx>
---
fs/ioctl.c | 101 +++++++++++++++++++++++++++++++++++++++++----
include/linux/fs.h | 12 ++++++
2 files changed, 105 insertions(+), 8 deletions(-)
diff --git a/fs/ioctl.c b/fs/ioctl.c
index 76cf22ac97d7..f72c8da47d21 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -763,6 +763,38 @@ static int ioctl_fssetxattr(struct file *file, void __user *argp)
return err;
}
+/*
+ * Safeguard to maintain a list of valid IOCTLs handled by do_vfs_ioctl()
+ * instead of def_blk_fops or def_chr_fops (see init_special_inode).
+ */
+__attribute_const__ bool vfs_masked_device_ioctl(const unsigned int cmd)
+{
+ switch (cmd) {
+ case FIOCLEX:
+ case FIONCLEX:
+ case FIONBIO:
+ case FIOASYNC:
+ case FIOQSIZE:
+ case FIFREEZE:
+ case FITHAW:
+ case FS_IOC_FIEMAP:
+ case FIGETBSZ:
+ case FICLONE:
+ case FICLONERANGE:
+ case FIDEDUPERANGE:
+ /* FIONREAD is forwarded to device implementations. */
+ case FS_IOC_GETFLAGS:
+ case FS_IOC_SETFLAGS:
+ case FS_IOC_FSGETXATTR:
+ case FS_IOC_FSSETXATTR:
+ /* file_ioctl()'s IOCTLs are forwarded to device implementations. */
+ return true;
+ default:
+ return false;
+ }
+}
+EXPORT_SYMBOL(vfs_masked_device_ioctl);
+
/*
* 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.
@@ -858,6 +890,8 @@ SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
{
struct fd f = fdget(fd);
int error;
+ const struct inode *inode;
+ bool is_device;
if (!f.file)
return -EBADF;
@@ -866,9 +900,18 @@ SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
if (error)
goto out;
+ inode = file_inode(f.file);
+ is_device = S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode);
+ if (is_device && !vfs_masked_device_ioctl(cmd)) {
+ error = vfs_ioctl(f.file, cmd, arg);
+ goto out;
+ }
+
error = do_vfs_ioctl(f.file, fd, cmd, arg);
- if (error == -ENOIOCTLCMD)
+ if (error == -ENOIOCTLCMD) {
+ WARN_ON_ONCE(is_device);
error = vfs_ioctl(f.file, cmd, arg);
+ }
out:
fdput(f);
@@ -911,11 +954,49 @@ long compat_ptr_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
}
EXPORT_SYMBOL(compat_ptr_ioctl);
+static long ioctl_compat(struct file *filp, unsigned int cmd,
+ compat_ulong_t arg)
+{
+ int error = -ENOTTY;
+
+ if (!filp->f_op->compat_ioctl)
+ goto out;
+
+ error = filp->f_op->compat_ioctl(filp, cmd, arg);
+ if (error == -ENOIOCTLCMD)
+ error = -ENOTTY;
+
+out:
+ return error;
+}
+
+__attribute_const__ bool vfs_masked_device_ioctl_compat(const unsigned int cmd)
+{
+ switch (cmd) {
+ case FICLONE:
+#if defined(CONFIG_X86_64)
+ case FS_IOC_RESVSP_32:
+ case FS_IOC_RESVSP64_32:
+ case FS_IOC_UNRESVSP_32:
+ case FS_IOC_UNRESVSP64_32:
+ case FS_IOC_ZERO_RANGE_32:
+#endif
+ case FS_IOC32_GETFLAGS:
+ case FS_IOC32_SETFLAGS:
+ return true;
+ default:
+ return vfs_masked_device_ioctl(cmd);
+ }
+}
+EXPORT_SYMBOL(vfs_masked_device_ioctl_compat);
+
COMPAT_SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd,
compat_ulong_t, arg)
{
struct fd f = fdget(fd);
int error;
+ const struct inode *inode;
+ bool is_device;
if (!f.file)
return -EBADF;
@@ -924,6 +1005,13 @@ COMPAT_SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd,
if (error)
goto out;
+ inode = file_inode(f.file);
+ is_device = S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode);
+ if (is_device && !vfs_masked_device_ioctl_compat(cmd)) {
+ error = ioctl_compat(f.file, cmd, arg);
+ goto out;
+ }
+
switch (cmd) {
/* FICLONE takes an int argument, so don't use compat_ptr() */
case FICLONE:
@@ -964,13 +1052,10 @@ COMPAT_SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd,
default:
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)
- error = -ENOTTY;
+ if (error == -ENOIOCTLCMD) {
+ WARN_ON_ONCE(is_device);
+ error = ioctl_compat(f.file, cmd, arg);
+ }
break;
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index ed5966a70495..b620d0c00e16 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1902,6 +1902,18 @@ extern long compat_ptr_ioctl(struct file *file, unsigned int cmd,
#define compat_ptr_ioctl NULL
#endif
+extern __attribute_const__ bool vfs_masked_device_ioctl(const unsigned int cmd);
+#ifdef CONFIG_COMPAT
+extern __attribute_const__ bool
+vfs_masked_device_ioctl_compat(const unsigned int cmd);
+#else /* CONFIG_COMPAT */
+static inline __attribute_const__ bool
+vfs_masked_device_ioctl_compat(const unsigned int cmd)
+{
+ return vfs_masked_device_ioctl(cmd);
+}
+#endif /* CONFIG_COMPAT */
+
/*
* VFS file helper functions.
*/
--
2.43.0
