For backing file operations, users are expected to pass credentials
that will outlive the backing file common operations.
Use the specialized guard statements to override/revert the
credentials.
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@xxxxxxxxx>
---
fs/backing-file.c | 27 +++++++--------------------
1 file changed, 7 insertions(+), 20 deletions(-)
diff --git a/fs/backing-file.c b/fs/backing-file.c
index a681f38d84d8..2cd015f49382 100644
--- a/fs/backing-file.c
+++ b/fs/backing-file.c
@@ -140,7 +140,6 @@ ssize_t backing_file_read_iter(struct file *file, struct iov_iter *iter,
struct backing_file_ctx *ctx)
{
struct backing_aio *aio = NULL;
- const struct cred *old_cred;
ssize_t ret;
if (WARN_ON_ONCE(!(file->f_mode & FMODE_BACKING)))
@@ -153,7 +152,7 @@ ssize_t backing_file_read_iter(struct file *file, struct iov_iter *iter,
!(file->f_mode & FMODE_CAN_ODIRECT))
return -EINVAL;
- old_cred = override_creds(ctx->cred);
+ guard(cred)(ctx->cred);
if (is_sync_kiocb(iocb)) {
rwf_t rwf = iocb_to_rw_flags(flags);
@@ -174,8 +173,6 @@ ssize_t backing_file_read_iter(struct file *file, struct iov_iter *iter,
backing_aio_cleanup(aio, ret);
}
out:
- revert_creds(old_cred);
-
if (ctx->accessed)
ctx->accessed(ctx->user_file);
@@ -187,7 +184,6 @@ ssize_t backing_file_write_iter(struct file *file, struct iov_iter *iter,
struct kiocb *iocb, int flags,
struct backing_file_ctx *ctx)
{
- const struct cred *old_cred;
ssize_t ret;
if (WARN_ON_ONCE(!(file->f_mode & FMODE_BACKING)))
@@ -210,7 +206,7 @@ ssize_t backing_file_write_iter(struct file *file, struct iov_iter *iter,
*/
flags &= ~IOCB_DIO_CALLER_COMP;
- old_cred = override_creds(ctx->cred);
+ guard(cred)(ctx->cred);
if (is_sync_kiocb(iocb)) {
rwf_t rwf = iocb_to_rw_flags(flags);
@@ -222,12 +218,12 @@ ssize_t backing_file_write_iter(struct file *file, struct iov_iter *iter,
ret = backing_aio_init_wq(iocb);
if (ret)
- goto out;
+ return ret;
ret = -ENOMEM;
aio = kmem_cache_zalloc(backing_aio_cachep, GFP_KERNEL);
if (!aio)
- goto out;
+ return ret;
aio->orig_iocb = iocb;
aio->end_write = ctx->end_write;
@@ -240,9 +236,6 @@ ssize_t backing_file_write_iter(struct file *file, struct iov_iter *iter,
if (ret != -EIOCBQUEUED)
backing_aio_cleanup(aio, ret);
}
-out:
- revert_creds(old_cred);
-
return ret;
}
EXPORT_SYMBOL_GPL(backing_file_write_iter);
@@ -252,15 +245,13 @@ ssize_t backing_file_splice_read(struct file *in, loff_t *ppos,
unsigned int flags,
struct backing_file_ctx *ctx)
{
- const struct cred *old_cred;
ssize_t ret;
if (WARN_ON_ONCE(!(in->f_mode & FMODE_BACKING)))
return -EIO;
- old_cred = override_creds(ctx->cred);
+ guard(cred)(ctx->cred);
ret = vfs_splice_read(in, ppos, pipe, len, flags);
- revert_creds(old_cred);
if (ctx->accessed)
ctx->accessed(ctx->user_file);
@@ -274,7 +265,6 @@ ssize_t backing_file_splice_write(struct pipe_inode_info *pipe,
unsigned int flags,
struct backing_file_ctx *ctx)
{
- const struct cred *old_cred;
ssize_t ret;
if (WARN_ON_ONCE(!(out->f_mode & FMODE_BACKING)))
@@ -284,11 +274,10 @@ ssize_t backing_file_splice_write(struct pipe_inode_info *pipe,
if (ret)
return ret;
- old_cred = override_creds(ctx->cred);
+ guard(cred)(ctx->cred);
file_start_write(out);
ret = iter_file_splice_write(pipe, out, ppos, len, flags);
file_end_write(out);
- revert_creds(old_cred);
if (ctx->end_write)
ctx->end_write(ctx->user_file);
@@ -300,7 +289,6 @@ EXPORT_SYMBOL_GPL(backing_file_splice_write);
int backing_file_mmap(struct file *file, struct vm_area_struct *vma,
struct backing_file_ctx *ctx)
{
- const struct cred *old_cred;
int ret;
if (WARN_ON_ONCE(!(file->f_mode & FMODE_BACKING)) ||
@@ -312,9 +300,8 @@ int backing_file_mmap(struct file *file, struct vm_area_struct *vma,
vma_set_file(vma, file);
- old_cred = override_creds(ctx->cred);
+ guard(cred)(ctx->cred);
ret = call_mmap(vma->vm_file, vma);
- revert_creds(old_cred);
if (ctx->accessed)
ctx->accessed(ctx->user_file);
--
2.43.1
