[PATCH 5.15 66/83] fs: split off setxattr_copy and do_setxattr function from setxattr

Greg Kroah-Hartman
2022-10-03T07:37:28Z

From: Stefan Roesch <shr@fb.com>

[ Upstream commit 1a91794ce8481a293c5ef432feb440aee1455619 ]

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>
Link: https://lore.kernel.org/r/20220323154420.3301504-2-shr@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Stable-dep-of: 06bbaa6dc53c ("[coredump] don't use __kernel_write() on kmap_local_page()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/internal.h | 24 +++++++++++++++
fs/xattr.c | 84 ++++++++++++++++++++++++++++++++++++---------------
2 files changed, 83 insertions(+), 25 deletions(-)

diff --git a/fs/internal.h b/fs/internal.h
index cdd83d4899bb..4f1fe6d08866 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -195,3 +195,27 @@ 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 998045165916..7117cb253864 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -25,6 +25,8 @@

#include <linux/uaccess.h>

+#include "internal.h"
+
static const char *
strcmp_prefix(const char *a, const char *a_prefix)
{
@@ -539,44 +541,76 @@ 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 = NULL;
- char kname[XATTR_NAME_MAX + 1];

- if (flags & ~(XATTR_CREATE|XATTR_REPLACE))
+ if (ctx->flags & ~(XATTR_CREATE|XATTR_REPLACE))
return -EINVAL;

- error = strncpy_from_user(kname, name, sizeof(kname));
- if (error == 0 || error == sizeof(kname))
- error = -ERANGE;
+ error = strncpy_from_user(ctx->kname->name, name,
+ sizeof(ctx->kname->name));
+ if (error == 0 || error == sizeof(ctx->kname->name))
+ return -ERANGE;
if (error < 0)
return error;

- if (size) {
- if (size > XATTR_SIZE_MAX)
+ error = 0;
+ if (ctx->size) {
+ if (ctx->size > XATTR_SIZE_MAX)
return -E2BIG;
- kvalue = kvmalloc(size, GFP_KERNEL);
- if (!kvalue)
- return -ENOMEM;
- if (copy_from_user(kvalue, value, size)) {
- error = -EFAULT;
- goto out;
+
+ ctx->kvalue = vmemdup_user(ctx->cvalue, ctx->size);
+ if (IS_ERR(ctx->kvalue)) {
+ error = PTR_ERR(ctx->kvalue);
+ ctx->kvalue = NULL;
}
- if ((strcmp(kname, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
- (strcmp(kname, XATTR_NAME_POSIX_ACL_DEFAULT) == 0))
- posix_acl_fix_xattr_from_user(mnt_userns, d_inode(d),
- kvalue, size);
}

- error = vfs_setxattr(mnt_userns, d, kname, kvalue, size, flags);
-out:
- kvfree(kvalue);
+ return error;
+}
+
+static void setxattr_convert(struct user_namespace *mnt_userns,
+ struct dentry *d, struct xattr_ctx *ctx)
+{
+ if (ctx->size &&
+ ((strcmp(ctx->kname->name, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
+ (strcmp(ctx->kname->name, XATTR_NAME_POSIX_ACL_DEFAULT) == 0)))
+ posix_acl_fix_xattr_from_user(mnt_userns, d_inode(d),
+ ctx->kvalue, ctx->size);
+}
+
+int do_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+ struct xattr_ctx *ctx)
+{
+ setxattr_convert(mnt_userns, dentry, 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 = {
+ .cvalue = value,
+ .kvalue = NULL,
+ .size = size,
+ .kname = &kname,
+ .flags = flags,
+ };
+ int error;
+
+ error = setxattr_copy(name, &ctx);
+ if (error)
+ return error;
+
+ error = do_setxattr(mnt_userns, d, &ctx);

+ kvfree(ctx.kvalue);
return error;
}

--
2.35.1