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; }