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From: Stefan Roesch <shr@fb.com>
To: <io-uring@vger.kernel.org>, <linux-fsdevel@vger.kernel.org>,
<kernel-team@fb.com>
CC: <viro@zeniv.linux.org.uk>, <christian.brauner@ubuntu.com>,
<shr@fb.com>
Subject: [PATCH v13 1/4] fs: split off setxattr_copy and do_setxattr function from setxattr
Date: Wed, 23 Mar 2022 08:44:17 -0700
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This splits of the setup part of the function
setxattr in its own dedicated function called
setxattr_copy. In addition it also exposes a
new function called do_setxattr for making the
setxattr call.
This makes it possible to call these two functions
from io_uring in the processing of an xattr request.
Signed-off-by: Stefan Roesch <shr@fb.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
---
fs/internal.h | 24 +++++++++++++++
fs/xattr.c | 82 ++++++++++++++++++++++++++++++++++++---------------
2 files changed, 82 insertions(+), 24 deletions(-)
diff --git a/fs/internal.h b/fs/internal.h
index 56c0477f4215..96bbab6b58ba 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -196,3 +196,27 @@ long splice_file_to_pipe(struct file *in,
struct pipe_inode_info *opipe,
loff_t *offset,
size_t len, unsigned int flags);
+
+/*
+ * fs/xattr.c:
+ */
+struct xattr_name {
+ char name[XATTR_NAME_MAX + 1];
+};
+
+struct xattr_ctx {
+ /* Value of attribute */
+ union {
+ const void __user *cvalue;
+ void __user *value;
+ };
+ void *kvalue;
+ size_t size;
+ /* Attribute name */
+ struct xattr_name *kname;
+ unsigned int flags;
+};
+
+int setxattr_copy(const char __user *name, struct xattr_ctx *ctx);
+int do_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry=
,
+ struct xattr_ctx *ctx);
diff --git a/fs/xattr.c b/fs/xattr.c
index 5c8c5175b385..717b3904c2e5 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -25,6 +25,8 @@
=20
#include <linux/uaccess.h>
=20
+#include "internal.h"
+
static const char *
strcmp_prefix(const char *a, const char *a_prefix)
{
@@ -539,43 +541,75 @@ EXPORT_SYMBOL_GPL(vfs_removexattr);
/*
* Extended attribute SET operations
*/
-static long
-setxattr(struct user_namespace *mnt_userns, struct dentry *d,
- const char __user *name, const void __user *value, size_t size,
- int flags)
+
+int setxattr_copy(const char __user *name, struct xattr_ctx *ctx)
{
int error;
- void *kvalue =3D NULL;
- char kname[XATTR_NAME_MAX + 1];
=20
- if (flags & ~(XATTR_CREATE|XATTR_REPLACE))
+ if (ctx->flags & ~(XATTR_CREATE|XATTR_REPLACE))
return -EINVAL;
=20
- error =3D strncpy_from_user(kname, name, sizeof(kname));
- if (error =3D=3D 0 || error =3D=3D sizeof(kname))
- error =3D -ERANGE;
+ error =3D strncpy_from_user(ctx->kname->name, name,
+ sizeof(ctx->kname->name));
+ if (error =3D=3D 0 || error =3D=3D sizeof(ctx->kname->name))
+ return -ERANGE;
if (error < 0)
return error;
=20
- if (size) {
- if (size > XATTR_SIZE_MAX)
+ error =3D 0;
+ if (ctx->size) {
+ if (ctx->size > XATTR_SIZE_MAX)
return -E2BIG;
- kvalue =3D kvmalloc(size, GFP_KERNEL);
- if (!kvalue)
- return -ENOMEM;
- if (copy_from_user(kvalue, value, size)) {
- error =3D -EFAULT;
- goto out;
+
+ ctx->kvalue =3D vmemdup_user(ctx->cvalue, ctx->size);
+ if (IS_ERR(ctx->kvalue)) {
+ error =3D PTR_ERR(ctx->kvalue);
+ ctx->kvalue =3D NULL;
}
- if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) =3D=3D 0) ||
- (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) =3D=3D 0))
- posix_acl_fix_xattr_from_user(mnt_userns, kvalue, size);
}
=20
- error =3D vfs_setxattr(mnt_userns, d, kname, kvalue, size, flags);
-out:
- kvfree(kvalue);
+ return error;
+}
+
+static void setxattr_convert(struct user_namespace *mnt_userns,
+ struct xattr_ctx *ctx)
+{
+ if (ctx->size &&
+ ((strcmp(ctx->kname->name, XATTR_NAME_POSIX_ACL_ACCESS) =3D=3D 0) ||
+ (strcmp(ctx->kname->name, XATTR_NAME_POSIX_ACL_DEFAULT) =3D=3D 0)))
+ posix_acl_fix_xattr_from_user(mnt_userns, ctx->kvalue, ctx->size);
+}
+
+int do_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry=
,
+ struct xattr_ctx *ctx)
+{
+ setxattr_convert(mnt_userns, ctx);
+ return vfs_setxattr(mnt_userns, dentry, ctx->kname->name,
+ ctx->kvalue, ctx->size, ctx->flags);
+}
+
+static long
+setxattr(struct user_namespace *mnt_userns, struct dentry *d,
+ const char __user *name, const void __user *value, size_t size,
+ int flags)
+{
+ struct xattr_name kname;
+ struct xattr_ctx ctx =3D {
+ .cvalue =3D value,
+ .kvalue =3D NULL,
+ .size =3D size,
+ .kname =3D &kname,
+ .flags =3D flags,
+ };
+ int error;
+
+ error =3D setxattr_copy(name, &ctx);
+ if (error)
+ return error;
+
+ error =3D do_setxattr(mnt_userns, d, &ctx);
=20
+ kvfree(ctx.kvalue);
return error;
}
=20
--=20
2.30.2