diff mbox series

[16/39] convert __bpf_prog_get() to CLASS(fd, ...)

Message ID 20240730051625.14349-16-viro@kernel.org (mailing list archive)
State Not Applicable
Delegated to: BPF
Headers show
Series [01/39] memcg_write_event_control(): fix a user-triggerable oops | expand

Checks

Context Check Description
netdev/tree_selection success Guessing tree name failed - patch did not apply, async

Commit Message

Al Viro July 30, 2024, 5:16 a.m. UTC 
From: Al Viro <viro@zeniv.linux.org.uk>

Irregularity here is fdput() not in the same scope as fdget();
just fold ____bpf_prog_get() into its (only) caller and that's
it...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 kernel/bpf/syscall.c | 32 +++++++++++---------------------
 1 file changed, 11 insertions(+), 21 deletions(-)

Comments

Andrii Nakryiko Aug. 6, 2024, 9:08 p.m. UTC | #1 
On Mon, Jul 29, 2024 at 10:19 PM <viro@kernel.org> wrote:
>
> From: Al Viro <viro@zeniv.linux.org.uk>
>
> Irregularity here is fdput() not in the same scope as fdget();
> just fold ____bpf_prog_get() into its (only) caller and that's
> it...
>
> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
> ---
>  kernel/bpf/syscall.c | 32 +++++++++++---------------------
>  1 file changed, 11 insertions(+), 21 deletions(-)
>

Folding makes total sense, the logic lgtm (though I find CLASS(fd,
f)(ufd) utterly non-intuitive naming-wise). Extra IS_ERR(prog) check
should be dropped though, see below.

Acked-by: Andrii Nakryiko <andrii@kernel.org>

> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 3093bf2cc266..c5b252c0faa8 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -2407,18 +2407,6 @@ int bpf_prog_new_fd(struct bpf_prog *prog)
>                                 O_RDWR | O_CLOEXEC);
>  }
>
> -static struct bpf_prog *____bpf_prog_get(struct fd f)
> -{
> -       if (!fd_file(f))
> -               return ERR_PTR(-EBADF);
> -       if (fd_file(f)->f_op != &bpf_prog_fops) {
> -               fdput(f);
> -               return ERR_PTR(-EINVAL);
> -       }
> -
> -       return fd_file(f)->private_data;
> -}
> -
>  void bpf_prog_add(struct bpf_prog *prog, int i)
>  {
>         atomic64_add(i, &prog->aux->refcnt);
> @@ -2474,20 +2462,22 @@ bool bpf_prog_get_ok(struct bpf_prog *prog,
>  static struct bpf_prog *__bpf_prog_get(u32 ufd, enum bpf_prog_type *attach_type,
>                                        bool attach_drv)
>  {
> -       struct fd f = fdget(ufd);
> +       CLASS(fd, f)(ufd);
>         struct bpf_prog *prog;
>
> -       prog = ____bpf_prog_get(f);
> -       if (IS_ERR(prog))
> +       if (fd_empty(f))
> +               return ERR_PTR(-EBADF);
> +       if (fd_file(f)->f_op != &bpf_prog_fops)
> +               return ERR_PTR(-EINVAL);
> +
> +       prog = fd_file(f)->private_data;
> +       if (IS_ERR(prog))       // can that actually happen?

no, it can't, private_data will always be a valid pointer, otherwise
that file would never be successfully created

>                 return prog;
> -       if (!bpf_prog_get_ok(prog, attach_type, attach_drv)) {
> -               prog = ERR_PTR(-EINVAL);
> -               goto out;
> -       }
> +
> +       if (!bpf_prog_get_ok(prog, attach_type, attach_drv))
> +               return ERR_PTR(-EINVAL);
>
>         bpf_prog_inc(prog);
> -out:
> -       fdput(f);
>         return prog;
>  }
>
> --
> 2.39.2
>
>
Christian Brauner Aug. 7, 2024, 10:28 a.m. UTC | #2 
On Tue, Jul 30, 2024 at 01:16:02AM GMT, viro@kernel.org wrote:
> From: Al Viro <viro@zeniv.linux.org.uk>
> 
> Irregularity here is fdput() not in the same scope as fdget();
> just fold ____bpf_prog_get() into its (only) caller and that's
> it...
> 
> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
> ---
>  kernel/bpf/syscall.c | 32 +++++++++++---------------------
>  1 file changed, 11 insertions(+), 21 deletions(-)
> 
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 3093bf2cc266..c5b252c0faa8 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -2407,18 +2407,6 @@ int bpf_prog_new_fd(struct bpf_prog *prog)
>  				O_RDWR | O_CLOEXEC);
>  }
>  
> -static struct bpf_prog *____bpf_prog_get(struct fd f)
> -{
> -	if (!fd_file(f))
> -		return ERR_PTR(-EBADF);
> -	if (fd_file(f)->f_op != &bpf_prog_fops) {
> -		fdput(f);
> -		return ERR_PTR(-EINVAL);
> -	}
> -
> -	return fd_file(f)->private_data;
> -}
> -
>  void bpf_prog_add(struct bpf_prog *prog, int i)
>  {
>  	atomic64_add(i, &prog->aux->refcnt);
> @@ -2474,20 +2462,22 @@ bool bpf_prog_get_ok(struct bpf_prog *prog,
>  static struct bpf_prog *__bpf_prog_get(u32 ufd, enum bpf_prog_type *attach_type,
>  				       bool attach_drv)
>  {
> -	struct fd f = fdget(ufd);
> +	CLASS(fd, f)(ufd);
>  	struct bpf_prog *prog;
>  
> -	prog = ____bpf_prog_get(f);
> -	if (IS_ERR(prog))
> +	if (fd_empty(f))
> +		return ERR_PTR(-EBADF);
> +	if (fd_file(f)->f_op != &bpf_prog_fops)
> +		return ERR_PTR(-EINVAL);
> +
> +	prog = fd_file(f)->private_data;
> +	if (IS_ERR(prog))	// can that actually happen?
>  		return prog;

With or without that removed:

Reviewed-by: Christian Brauner <brauner@kernel.org>
diff mbox series

Patch

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 3093bf2cc266..c5b252c0faa8 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2407,18 +2407,6 @@  int bpf_prog_new_fd(struct bpf_prog *prog)
 				O_RDWR | O_CLOEXEC);
 }
 
-static struct bpf_prog *____bpf_prog_get(struct fd f)
-{
-	if (!fd_file(f))
-		return ERR_PTR(-EBADF);
-	if (fd_file(f)->f_op != &bpf_prog_fops) {
-		fdput(f);
-		return ERR_PTR(-EINVAL);
-	}
-
-	return fd_file(f)->private_data;
-}
-
 void bpf_prog_add(struct bpf_prog *prog, int i)
 {
 	atomic64_add(i, &prog->aux->refcnt);
@@ -2474,20 +2462,22 @@  bool bpf_prog_get_ok(struct bpf_prog *prog,
 static struct bpf_prog *__bpf_prog_get(u32 ufd, enum bpf_prog_type *attach_type,
 				       bool attach_drv)
 {
-	struct fd f = fdget(ufd);
+	CLASS(fd, f)(ufd);
 	struct bpf_prog *prog;
 
-	prog = ____bpf_prog_get(f);
-	if (IS_ERR(prog))
+	if (fd_empty(f))
+		return ERR_PTR(-EBADF);
+	if (fd_file(f)->f_op != &bpf_prog_fops)
+		return ERR_PTR(-EINVAL);
+
+	prog = fd_file(f)->private_data;
+	if (IS_ERR(prog))	// can that actually happen?
 		return prog;
-	if (!bpf_prog_get_ok(prog, attach_type, attach_drv)) {
-		prog = ERR_PTR(-EINVAL);
-		goto out;
-	}
+
+	if (!bpf_prog_get_ok(prog, attach_type, attach_drv))
+		return ERR_PTR(-EINVAL);
 
 	bpf_prog_inc(prog);
-out:
-	fdput(f);
 	return prog;
 }