On 12/23/21 6:52 AM, Christian Brauner wrote:
> On Wed, Dec 22, 2021 at 01:01:26PM -0800, Stefan Roesch wrote:
>> This adds support to io_uring for the fsetxattr and setxattr API.
>>
>> Signed-off-by: Stefan Roesch <shr@xxxxxx>
>> ---
>> fs/io_uring.c | 170 ++++++++++++++++++++++++++++++++++
>> include/uapi/linux/io_uring.h | 6 +-
>> 2 files changed, 175 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>> index c8258c784116..8b6c70d6cacc 100644
>> --- a/fs/io_uring.c
>> +++ b/fs/io_uring.c
>> @@ -82,6 +82,7 @@
>> #include <linux/audit.h>
>> #include <linux/security.h>
>> #include <linux/atomic-ref.h>
>> +#include <linux/xattr.h>
>>
>> #define CREATE_TRACE_POINTS
>> #include <trace/events/io_uring.h>
>> @@ -726,6 +727,13 @@ struct io_async_rw {
>> struct wait_page_queue wpq;
>> };
>>
>> +struct io_xattr {
>> + struct file *file;
>> + struct xattr_ctx ctx;
>> + void *value;
>> + struct filename *filename;
>> +};
>> +
>> enum {
>> REQ_F_FIXED_FILE_BIT = IOSQE_FIXED_FILE_BIT,
>> REQ_F_IO_DRAIN_BIT = IOSQE_IO_DRAIN_BIT,
>> @@ -866,6 +874,7 @@ struct io_kiocb {
>> struct io_symlink symlink;
>> struct io_hardlink hardlink;
>> struct io_getdents getdents;
>> + struct io_xattr xattr;
>> };
>>
>> u8 opcode;
>> @@ -1118,6 +1127,10 @@ static const struct io_op_def io_op_defs[] = {
>> [IORING_OP_GETDENTS] = {
>> .needs_file = 1,
>> },
>> + [IORING_OP_FSETXATTR] = {
>> + .needs_file = 1
>> + },
>> + [IORING_OP_SETXATTR] = {},
>> };
>>
>> /* requests with any of those set should undergo io_disarm_next() */
>> @@ -3887,6 +3900,144 @@ static int io_renameat(struct io_kiocb *req, unsigned int issue_flags)
>> return 0;
>> }
>>
>> +static int __io_setxattr_prep(struct io_kiocb *req,
>> + const struct io_uring_sqe *sqe,
>> + struct user_namespace *user_ns)
>> +{
>> + struct io_xattr *ix = &req->xattr;
>> + const char __user *name;
>> + void *ret;
>> +
>> + if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
>> + return -EINVAL;
>> + if (unlikely(sqe->ioprio))
>> + return -EINVAL;
>> + if (unlikely(req->flags & REQ_F_FIXED_FILE))
>> + return -EBADF;
>> +
>> + ix->filename = NULL;
>> + name = u64_to_user_ptr(READ_ONCE(sqe->addr));
>> + ix->ctx.value = u64_to_user_ptr(READ_ONCE(sqe->addr2));
>> + ix->ctx.size = READ_ONCE(sqe->len);
>> + ix->ctx.flags = READ_ONCE(sqe->xattr_flags);
>> +
>> + ix->ctx.kname = kmalloc(XATTR_NAME_MAX + 1, GFP_KERNEL);
>> + if (!ix->ctx.kname)
>> + return -ENOMEM;
>> + ix->ctx.kname_sz = XATTR_NAME_MAX + 1;
>> +
>> + ret = setxattr_setup(user_ns, name, &ix->ctx);
>
> Looking at this a bit closer, the setxattr_setup() function converts the
> vfs caps prior to vfs_setxattr(). That shouldn't be done there though.
> The conversion should be done when mnt_want_write() is held in
> __io_setxattr() exactly how we do for setxattr()-based calls in
> fs/xattr.c. This will guard against changes of relevant mount properties
> (current or future). It will also allow you to simplify your
> setxattr_setup() function a bit and you don't need to retrieve the
> mount's idmapping until __io_setxattr().
>
> Right now you're splitting updating the xattrs over the prep and commit
> stage and I worry that in fully async contexts this is easy to miss. So
> I'd rather do it in one place. Since we can't move it all into
> vfs_setxattr() similar to what we did for fscaps because it's used in a
> bunch of contexts where the conversion isn't wanted we should simply
> expose do_setxattr() similar to do_getxattr() you're adding.
>
> So on top of your current patchset I'd suggest you do something like the
> following (completely untested):
>
Thanks for your review and the code. I only changed the below code that the
do_setxattr does not use a kvalue, I assume you wanted to use xattr_val.
> From 6bcd3efc3293bb91599ee73272262ac596ab4608 Mon Sep 17 00:00:00 2001
> From: Christian Brauner <christian.brauner@xxxxxxxxxx>
> Date: Thu, 23 Dec 2021 15:23:14 +0100
> Subject: [PATCH] UNTESTED
>
> ---
> fs/internal.h | 8 +++++---
> fs/io_uring.c | 21 +++++++++-----------
> fs/xattr.c | 55 ++++++++++++++++++++++++++++++++++-----------------
> 3 files changed, 51 insertions(+), 33 deletions(-)
>
> diff --git a/fs/internal.h b/fs/internal.h
> index ea0433799dbc..08259fa98b2e 100644
> --- a/fs/internal.h
> +++ b/fs/internal.h
> @@ -222,6 +222,8 @@ ssize_t do_getxattr(struct user_namespace *mnt_userns,
> void __user *value,
> size_t size);
>
> -void *setxattr_setup(struct user_namespace *mnt_userns,
> - const char __user *name,
> - struct xattr_ctx *ctx);
> +int do_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
> + struct xattr_ctx *ctx, void *xattr_val);
> +
> +int setxattr_copy(const char __user *name, struct xattr_ctx *ctx,
> + void **xattr_val);
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 5dd01f19d915..c910c29e1632 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -4040,12 +4040,11 @@ static int io_getxattr(struct io_kiocb *req, unsigned int issue_flags)
> }
>
> static int __io_setxattr_prep(struct io_kiocb *req,
> - const struct io_uring_sqe *sqe,
> - struct user_namespace *user_ns)
> + const struct io_uring_sqe *sqe)
> {
> struct io_xattr *ix = &req->xattr;
> const char __user *name;
> - void *ret;
> + int ret;
>
> if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
> return -EINVAL;
> @@ -4065,13 +4064,12 @@ static int __io_setxattr_prep(struct io_kiocb *req,
> return -ENOMEM;
> ix->ctx.kname_sz = XATTR_NAME_MAX + 1;
>
> - ret = setxattr_setup(user_ns, name, &ix->ctx);
> - if (IS_ERR(ret)) {
> + ret = setxattr_copy(name, &ix->ctx, &ix->value);
> + if (ret) {
> kfree(ix->ctx.kname);
> - return PTR_ERR(ret);
> + return ret;
> }
>
> - ix->value = ret;
> req->flags |= REQ_F_NEED_CLEANUP;
> return 0;
> }
> @@ -4083,7 +4081,7 @@ static int io_setxattr_prep(struct io_kiocb *req,
> const char __user *path;
> int ret;
>
> - ret = __io_setxattr_prep(req, sqe, current_user_ns());
> + ret = __io_setxattr_prep(req, sqe);
> if (ret)
> return ret;
>
> @@ -4101,7 +4099,7 @@ static int io_setxattr_prep(struct io_kiocb *req,
> static int io_fsetxattr_prep(struct io_kiocb *req,
> const struct io_uring_sqe *sqe)
> {
> - return __io_setxattr_prep(req, sqe, file_mnt_user_ns(req->file));
> + return __io_setxattr_prep(req, sqe);
> }
>
> static int __io_setxattr(struct io_kiocb *req, unsigned int issue_flags,
> @@ -4112,9 +4110,8 @@ static int __io_setxattr(struct io_kiocb *req, unsigned int issue_flags,
>
> ret = mnt_want_write(path->mnt);
> if (!ret) {
> - ret = vfs_setxattr(mnt_user_ns(path->mnt), path->dentry,
> - ix->ctx.kname, ix->value, ix->ctx.size,
> - ix->ctx.flags);
> + ret = do_setxattr(mnt_user_ns(path->mnt), path->dentry,
> + &ix->ctx, ix->value);
> mnt_drop_write(path->mnt);
> }
>
> diff --git a/fs/xattr.c b/fs/xattr.c
> index a675c7f0ea0c..03a44c5895d1 100644
> --- a/fs/xattr.c
> +++ b/fs/xattr.c
> @@ -542,40 +542,59 @@ EXPORT_SYMBOL_GPL(vfs_removexattr);
> * Extended attribute SET operations
> */
>
> -void *setxattr_setup(struct user_namespace *mnt_userns, const char __user *name,
> - struct xattr_ctx *ctx)
> +int setxattr_copy(const char __user *name, struct xattr_ctx *ctx,
> + void **xattr_val)
> {
> void *kvalue = NULL;
> int error;
>
> if (ctx->flags & ~(XATTR_CREATE|XATTR_REPLACE))
> - return ERR_PTR(-EINVAL);
> + return -EINVAL;
>
> error = strncpy_from_user(ctx->kname, name, ctx->kname_sz);
> if (error == 0 || error == ctx->kname_sz)
> - return ERR_PTR(-ERANGE);
> + return -ERANGE;
> if (error < 0)
> - return ERR_PTR(error);
> + return error;
>
> if (ctx->size) {
> if (ctx->size > XATTR_SIZE_MAX)
> - return ERR_PTR(-E2BIG);
> + return -E2BIG;
>
> kvalue = kvmalloc(ctx->size, GFP_KERNEL);
> if (!kvalue)
> - return ERR_PTR(-ENOMEM);
> + return -ENOMEM;
>
> if (copy_from_user(kvalue, ctx->value, ctx->size)) {
> kvfree(kvalue);
> - return ERR_PTR(-EFAULT);
> + return -EFAULT;
> }
> -
> - if ((strcmp(ctx->kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
> - (strcmp(ctx->kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))
> - posix_acl_fix_xattr_from_user(mnt_userns, kvalue, ctx->size);
> }
>
> - return kvalue;
> + *xattr_val = kvalue;
> + return 0;
> +}
> +
> +static void setxattr_convert(struct user_namespace *mnt_userns,
> + struct xattr_ctx *ctx, void *kvalue)
> +{
> + if (ctx->size &&
> + ((strcmp(ctx->kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
> + (strcmp(ctx->kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0)))
> + posix_acl_fix_xattr_from_user(mnt_userns, kvalue, ctx->size);
> +}
> +
> +int do_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
> + struct xattr_ctx *ctx, void *xattr_val)
> +{
> + void *kvalue = NULL;
> + int error;
> +
> + setxattr_convert(mnt_userns, ctx, kvalue);
> + error = vfs_setxattr(mnt_userns, dentry, ctx->kname,
> + kvalue, ctx->size, ctx->flags);
> + kvfree(kvalue);
> + return error;
> }
>
> static long
> @@ -591,14 +610,14 @@ setxattr(struct user_namespace *mnt_userns, struct dentry *d,
> .kname_sz = sizeof(kname),
> .flags = flags,
> };
> - void *kvalue;
> + void *kvalue = NULL;
> int error;
>
> - kvalue = setxattr_setup(mnt_userns, name, &ctx);
> - if (IS_ERR(kvalue))
> - return PTR_ERR(kvalue);
> + error = setxattr_copy(name, &ctx, &kvalue);
> + if (error)
> + return error;
>
> - error = vfs_setxattr(mnt_userns, d, kname, kvalue, size, flags);
> + error = do_setxattr(mnt_userns, d, &ctx, kvalue);
>
> kvfree(kvalue);
> return error;
>
