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afs: Get an AFS3 ACL as an xattr

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Implement an xattr on AFS files called "afs.acl" that retrieves a file's
ACL.  It returns the raw AFS3 ACL from the result of calling FS.FetchACL,
leaving any interpretation to userspace.

Note that whilst YFS servers will respond to FS.FetchACL, this will render
a more-advanced YFS ACL down.  Use "afs.yfs.acl" instead for that.

Signed-off-by: David Howells <dhowells@redhat.com>
This commit is contained in:
David Howells
2019-04-25 14:26:52 +01:00
parent a2f611a3dc
commit 260f082bae
5 changed files with 184 additions and 0 deletions
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53
fs/afs/xattr.c
View File

@@ -16,6 +16,7 @@
#include "internal.h"
static const char afs_xattr_list[] =
"afs.acl\0"
"afs.cell\0"
"afs.fid\0"
"afs.volume";
@@ -33,6 +34,57 @@ ssize_t afs_listxattr(struct dentry *dentry, char *buffer, size_t size)
return sizeof(afs_xattr_list);
}
/*
* Get a file's ACL.
*/
static int afs_xattr_get_acl(const struct xattr_handler *handler,
struct dentry *dentry,
struct inode *inode, const char *name,
void *buffer, size_t size)
{
struct afs_fs_cursor fc;
struct afs_vnode *vnode = AFS_FS_I(inode);
struct afs_acl *acl = NULL;
struct key *key;
int ret;
key = afs_request_key(vnode->volume->cell);
if (IS_ERR(key))
return PTR_ERR(key);
ret = -ERESTARTSYS;
if (afs_begin_vnode_operation(&fc, vnode, key)) {
while (afs_select_fileserver(&fc)) {
fc.cb_break = afs_calc_vnode_cb_break(vnode);
acl = afs_fs_fetch_acl(&fc);
}
afs_check_for_remote_deletion(&fc, fc.vnode);
afs_vnode_commit_status(&fc, vnode, fc.cb_break);
ret = afs_end_vnode_operation(&fc);
}
if (ret == 0) {
ret = acl->size;
if (size > 0) {
ret = -ERANGE;
if (acl->size > size)
return -ERANGE;
memcpy(buffer, acl->data, acl->size);
ret = acl->size;
}
kfree(acl);
}
key_put(key);
return ret;
}
static const struct xattr_handler afs_xattr_afs_acl_handler = {
.name = "afs.acl",
.get = afs_xattr_get_acl,
};
/*
* Get the name of the cell on which a file resides.
*/
@@ -123,6 +175,7 @@ static const struct xattr_handler afs_xattr_afs_volume_handler = {
};
const struct xattr_handler *afs_xattr_handlers[] = {
&afs_xattr_afs_acl_handler,
&afs_xattr_afs_cell_handler,
&afs_xattr_afs_fid_handler,
&afs_xattr_afs_volume_handler,