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Subject[PATCH 08/32] aio: replace kiocb_set_cancel_fn with a cancel_kiocb file operation
Date
The current kiocb_set_cancel_fn implementation assumes the kiocb is
embedded into an aio_kiocb, which is fundamentally unsafe as it might
have been submitted by non-aio callers. Instead add a cancel_kiocb
file operation that replaced the ki_cancel function pointer set by
kiocb_set_cancel_fn, and only adds iocbs to the active list when
the read/write_iter methods return -EIOCBQUEUED and the file has
a cancel_kiocb method.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/usb/gadget/function/f_fs.c | 10 ++--------
drivers/usb/gadget/legacy/inode.c | 5 ++---
fs/aio.c | 31 ++++++++++++------------------
fs/orangefs/orangefs-kernel.h | 1 -
include/linux/aio.h | 7 -------
include/linux/fs.h | 1 +
6 files changed, 17 insertions(+), 38 deletions(-)

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 0294e4f18873..531a7206407b 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -26,7 +26,6 @@
#include <linux/usb/composite.h>
#include <linux/usb/functionfs.h>

-#include <linux/aio.h>
#include <linux/mmu_context.h>
#include <linux/poll.h>
#include <linux/eventfd.h>
@@ -1072,7 +1071,7 @@ ffs_epfile_open(struct inode *inode, struct file *file)
return 0;
}

-static int ffs_aio_cancel(struct kiocb *kiocb)
+static int ffs_epfile_cancel_kiocb(struct kiocb *kiocb)
{
struct ffs_io_data *io_data = kiocb->private;
struct ffs_epfile *epfile = kiocb->ki_filp->private_data;
@@ -1115,9 +1114,6 @@ static ssize_t ffs_epfile_write_iter(struct kiocb *kiocb, struct iov_iter *from)

kiocb->private = p;

- if (p->aio)
- kiocb_set_cancel_fn(kiocb, ffs_aio_cancel);
-
res = ffs_epfile_io(kiocb->ki_filp, p);
if (res == -EIOCBQUEUED)
return res;
@@ -1160,9 +1156,6 @@ static ssize_t ffs_epfile_read_iter(struct kiocb *kiocb, struct iov_iter *to)

kiocb->private = p;

- if (p->aio)
- kiocb_set_cancel_fn(kiocb, ffs_aio_cancel);
-
res = ffs_epfile_io(kiocb->ki_filp, p);
if (res == -EIOCBQUEUED)
return res;
@@ -1274,6 +1267,7 @@ static const struct file_operations ffs_epfile_operations = {
.read_iter = ffs_epfile_read_iter,
.release = ffs_epfile_release,
.unlocked_ioctl = ffs_epfile_ioctl,
+ .cancel_kiocb = ffs_epfile_cancel_kiocb,
};


diff --git a/drivers/usb/gadget/legacy/inode.c b/drivers/usb/gadget/legacy/inode.c
index 37ca0e669bd8..02ea83c8861a 100644
--- a/drivers/usb/gadget/legacy/inode.c
+++ b/drivers/usb/gadget/legacy/inode.c
@@ -21,7 +21,6 @@
#include <linux/slab.h>
#include <linux/poll.h>
#include <linux/mmu_context.h>
-#include <linux/aio.h>
#include <linux/uio.h>
#include <linux/refcount.h>
#include <linux/delay.h>
@@ -435,7 +434,7 @@ struct kiocb_priv {
unsigned actual;
};

-static int ep_aio_cancel(struct kiocb *iocb)
+static int ep_cancel_kiocb(struct kiocb *iocb)
{
struct kiocb_priv *priv = iocb->private;
struct ep_data *epdata;
@@ -528,7 +527,6 @@ static ssize_t ep_aio(struct kiocb *iocb,
iocb->private = priv;
priv->iocb = iocb;

- kiocb_set_cancel_fn(iocb, ep_aio_cancel);
get_ep(epdata);
priv->epdata = epdata;
priv->actual = 0;
@@ -700,6 +698,7 @@ static const struct file_operations ep_io_operations = {
.unlocked_ioctl = ep_ioctl,
.read_iter = ep_read_iter,
.write_iter = ep_write_iter,
+ .cancel_kiocb = ep_cancel_kiocb,
};

/* ENDPOINT INITIALIZATION
diff --git a/fs/aio.c b/fs/aio.c
index 8991baa38d5d..be10dde20c8e 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -171,7 +171,6 @@ struct aio_kiocb {
};

struct kioctx *ki_ctx;
- kiocb_cancel_fn *ki_cancel;

struct iocb __user *ki_user_iocb; /* user's aiocb */
__u64 ki_user_data; /* user's data for completion */
@@ -545,22 +544,6 @@ static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
#define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
#define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)

-void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel)
-{
- struct aio_kiocb *req = container_of(iocb, struct aio_kiocb, rw);
- struct kioctx *ctx = req->ki_ctx;
- unsigned long flags;
-
- if (WARN_ON_ONCE(!list_empty(&req->ki_list)))
- return;
-
- spin_lock_irqsave(&ctx->ctx_lock, flags);
- list_add_tail(&req->ki_list, &ctx->active_reqs);
- req->ki_cancel = cancel;
- spin_unlock_irqrestore(&ctx->ctx_lock, flags);
-}
-EXPORT_SYMBOL(kiocb_set_cancel_fn);
-
/*
* free_ioctx() should be RCU delayed to synchronize against the RCU
* protected lookup_ioctx() and also needs process context to call
@@ -608,7 +591,7 @@ static void free_ioctx_users(struct percpu_ref *ref)
req = list_first_entry(&ctx->active_reqs,
struct aio_kiocb, ki_list);
list_del_init(&req->ki_list);
- req->ki_cancel(&req->rw);
+ req->rw.ki_filp->f_op->cancel_kiocb(&req->rw);
}

spin_unlock_irq(&ctx->ctx_lock);
@@ -1447,6 +1430,16 @@ static inline ssize_t aio_rw_ret(struct kiocb *req, ssize_t ret)
{
switch (ret) {
case -EIOCBQUEUED:
+ if (req->ki_filp->f_op->cancel_kiocb) {
+ struct aio_kiocb *iocb =
+ container_of(req, struct aio_kiocb, rw);
+ struct kioctx *ctx = iocb->ki_ctx;
+ unsigned long flags;
+
+ spin_lock_irqsave(&ctx->ctx_lock, flags);
+ list_add_tail(&iocb->ki_list, &ctx->active_reqs);
+ spin_unlock_irqrestore(&ctx->ctx_lock, flags);
+ }
return ret;
case -ERESTARTSYS:
case -ERESTARTNOINTR:
@@ -1824,7 +1817,7 @@ SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
kiocb = lookup_kiocb(ctx, iocb);
if (kiocb) {
list_del_init(&kiocb->ki_list);
- ret = kiocb->ki_cancel(&kiocb->rw);
+ ret = kiocb->rw.ki_filp->f_op->cancel_kiocb(&kiocb->rw);
}
spin_unlock_irq(&ctx->ctx_lock);

diff --git a/fs/orangefs/orangefs-kernel.h b/fs/orangefs/orangefs-kernel.h
index c29bb0ebc6bb..5cd598c59bdc 100644
--- a/fs/orangefs/orangefs-kernel.h
+++ b/fs/orangefs/orangefs-kernel.h
@@ -34,7 +34,6 @@
#include <linux/fs.h>
#include <linux/vmalloc.h>

-#include <linux/aio.h>
#include <linux/posix_acl.h>
#include <linux/posix_acl_xattr.h>
#include <linux/compat.h>
diff --git a/include/linux/aio.h b/include/linux/aio.h
index b83e68dd006f..42e3cc953005 100644
--- a/include/linux/aio.h
+++ b/include/linux/aio.h
@@ -4,20 +4,13 @@

#include <linux/aio_abi.h>

-struct kioctx;
-struct kiocb;
struct mm_struct;

-typedef int (kiocb_cancel_fn)(struct kiocb *);
-
/* prototypes */
#ifdef CONFIG_AIO
extern void exit_aio(struct mm_struct *mm);
-void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel);
#else
static inline void exit_aio(struct mm_struct *mm) { }
-static inline void kiocb_set_cancel_fn(struct kiocb *req,
- kiocb_cancel_fn *cancel) { }
#endif /* CONFIG_AIO */

/* for sysctl: */
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 4b6045ebb2f2..7fe64df9eb09 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1742,6 +1742,7 @@ struct file_operations {
u64);
ssize_t (*dedupe_file_range)(struct file *, u64, u64, struct file *,
u64);
+ int (*cancel_kiocb)(struct kiocb *);
} __randomize_layout;

struct inode_operations {
--
2.17.0
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