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-rw-r--r--fs/xfs/xfs_handle.c947
1 files changed, 947 insertions, 0 deletions
diff --git a/fs/xfs/xfs_handle.c b/fs/xfs/xfs_handle.c
new file mode 100644
index 0000000000..a3f16e9b6f
--- /dev/null
+++ b/fs/xfs/xfs_handle.c
@@ -0,0 +1,947 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2000-2005 Silicon Graphics, Inc.
+ * Copyright (c) 2022-2024 Oracle.
+ * All rights reserved.
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_shared.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_inode.h"
+#include "xfs_error.h"
+#include "xfs_trace.h"
+#include "xfs_trans.h"
+#include "xfs_da_format.h"
+#include "xfs_da_btree.h"
+#include "xfs_attr.h"
+#include "xfs_ioctl.h"
+#include "xfs_parent.h"
+#include "xfs_da_btree.h"
+#include "xfs_handle.h"
+#include "xfs_health.h"
+#include "xfs_icache.h"
+#include "xfs_export.h"
+#include "xfs_xattr.h"
+#include "xfs_acl.h"
+
+#include <linux/namei.h>
+
+static inline size_t
+xfs_filehandle_fid_len(void)
+{
+ struct xfs_handle *handle = NULL;
+
+ return sizeof(struct xfs_fid) - sizeof(handle->ha_fid.fid_len);
+}
+
+static inline size_t
+xfs_filehandle_init(
+ struct xfs_mount *mp,
+ xfs_ino_t ino,
+ uint32_t gen,
+ struct xfs_handle *handle)
+{
+ memcpy(&handle->ha_fsid, mp->m_fixedfsid, sizeof(struct xfs_fsid));
+
+ handle->ha_fid.fid_len = xfs_filehandle_fid_len();
+ handle->ha_fid.fid_pad = 0;
+ handle->ha_fid.fid_gen = gen;
+ handle->ha_fid.fid_ino = ino;
+
+ return sizeof(struct xfs_handle);
+}
+
+static inline size_t
+xfs_fshandle_init(
+ struct xfs_mount *mp,
+ struct xfs_handle *handle)
+{
+ memcpy(&handle->ha_fsid, mp->m_fixedfsid, sizeof(struct xfs_fsid));
+ memset(&handle->ha_fid, 0, sizeof(handle->ha_fid));
+
+ return sizeof(struct xfs_fsid);
+}
+
+/*
+ * xfs_find_handle maps from userspace xfs_fsop_handlereq structure to
+ * a file or fs handle.
+ *
+ * XFS_IOC_PATH_TO_FSHANDLE
+ * returns fs handle for a mount point or path within that mount point
+ * XFS_IOC_FD_TO_HANDLE
+ * returns full handle for a FD opened in user space
+ * XFS_IOC_PATH_TO_HANDLE
+ * returns full handle for a path
+ */
+int
+xfs_find_handle(
+ unsigned int cmd,
+ xfs_fsop_handlereq_t *hreq)
+{
+ int hsize;
+ xfs_handle_t handle;
+ struct inode *inode;
+ struct fd f = {NULL};
+ struct path path;
+ int error;
+ struct xfs_inode *ip;
+
+ if (cmd == XFS_IOC_FD_TO_HANDLE) {
+ f = fdget(hreq->fd);
+ if (!f.file)
+ return -EBADF;
+ inode = file_inode(f.file);
+ } else {
+ error = user_path_at(AT_FDCWD, hreq->path, 0, &path);
+ if (error)
+ return error;
+ inode = d_inode(path.dentry);
+ }
+ ip = XFS_I(inode);
+
+ /*
+ * We can only generate handles for inodes residing on a XFS filesystem,
+ * and only for regular files, directories or symbolic links.
+ */
+ error = -EINVAL;
+ if (inode->i_sb->s_magic != XFS_SB_MAGIC)
+ goto out_put;
+
+ error = -EBADF;
+ if (!S_ISREG(inode->i_mode) &&
+ !S_ISDIR(inode->i_mode) &&
+ !S_ISLNK(inode->i_mode))
+ goto out_put;
+
+
+ memcpy(&handle.ha_fsid, ip->i_mount->m_fixedfsid, sizeof(xfs_fsid_t));
+
+ if (cmd == XFS_IOC_PATH_TO_FSHANDLE)
+ hsize = xfs_fshandle_init(ip->i_mount, &handle);
+ else
+ hsize = xfs_filehandle_init(ip->i_mount, ip->i_ino,
+ inode->i_generation, &handle);
+
+ error = -EFAULT;
+ if (copy_to_user(hreq->ohandle, &handle, hsize) ||
+ copy_to_user(hreq->ohandlen, &hsize, sizeof(__s32)))
+ goto out_put;
+
+ error = 0;
+
+ out_put:
+ if (cmd == XFS_IOC_FD_TO_HANDLE)
+ fdput(f);
+ else
+ path_put(&path);
+ return error;
+}
+
+/*
+ * No need to do permission checks on the various pathname components
+ * as the handle operations are privileged.
+ */
+STATIC int
+xfs_handle_acceptable(
+ void *context,
+ struct dentry *dentry)
+{
+ return 1;
+}
+
+/* Convert handle already copied to kernel space into a dentry. */
+static struct dentry *
+xfs_khandle_to_dentry(
+ struct file *file,
+ struct xfs_handle *handle)
+{
+ struct xfs_fid64 fid = {
+ .ino = handle->ha_fid.fid_ino,
+ .gen = handle->ha_fid.fid_gen,
+ };
+
+ /*
+ * Only allow handle opens under a directory.
+ */
+ if (!S_ISDIR(file_inode(file)->i_mode))
+ return ERR_PTR(-ENOTDIR);
+
+ if (handle->ha_fid.fid_len != xfs_filehandle_fid_len())
+ return ERR_PTR(-EINVAL);
+
+ return exportfs_decode_fh(file->f_path.mnt, (struct fid *)&fid, 3,
+ FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG,
+ xfs_handle_acceptable, NULL);
+}
+
+/* Convert handle already copied to kernel space into an xfs_inode. */
+static struct xfs_inode *
+xfs_khandle_to_inode(
+ struct file *file,
+ struct xfs_handle *handle)
+{
+ struct xfs_inode *ip = XFS_I(file_inode(file));
+ struct xfs_mount *mp = ip->i_mount;
+ struct inode *inode;
+
+ if (!S_ISDIR(VFS_I(ip)->i_mode))
+ return ERR_PTR(-ENOTDIR);
+
+ if (handle->ha_fid.fid_len != xfs_filehandle_fid_len())
+ return ERR_PTR(-EINVAL);
+
+ inode = xfs_nfs_get_inode(mp->m_super, handle->ha_fid.fid_ino,
+ handle->ha_fid.fid_gen);
+ if (IS_ERR(inode))
+ return ERR_CAST(inode);
+
+ return XFS_I(inode);
+}
+
+/*
+ * Convert userspace handle data into a dentry.
+ */
+struct dentry *
+xfs_handle_to_dentry(
+ struct file *parfilp,
+ void __user *uhandle,
+ u32 hlen)
+{
+ xfs_handle_t handle;
+
+ if (hlen != sizeof(xfs_handle_t))
+ return ERR_PTR(-EINVAL);
+ if (copy_from_user(&handle, uhandle, hlen))
+ return ERR_PTR(-EFAULT);
+
+ return xfs_khandle_to_dentry(parfilp, &handle);
+}
+
+STATIC struct dentry *
+xfs_handlereq_to_dentry(
+ struct file *parfilp,
+ xfs_fsop_handlereq_t *hreq)
+{
+ return xfs_handle_to_dentry(parfilp, hreq->ihandle, hreq->ihandlen);
+}
+
+int
+xfs_open_by_handle(
+ struct file *parfilp,
+ xfs_fsop_handlereq_t *hreq)
+{
+ const struct cred *cred = current_cred();
+ int error;
+ int fd;
+ int permflag;
+ struct file *filp;
+ struct inode *inode;
+ struct dentry *dentry;
+ fmode_t fmode;
+ struct path path;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ dentry = xfs_handlereq_to_dentry(parfilp, hreq);
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+ inode = d_inode(dentry);
+
+ /* Restrict xfs_open_by_handle to directories & regular files. */
+ if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))) {
+ error = -EPERM;
+ goto out_dput;
+ }
+
+#if BITS_PER_LONG != 32
+ hreq->oflags |= O_LARGEFILE;
+#endif
+
+ permflag = hreq->oflags;
+ fmode = OPEN_FMODE(permflag);
+ if ((!(permflag & O_APPEND) || (permflag & O_TRUNC)) &&
+ (fmode & FMODE_WRITE) && IS_APPEND(inode)) {
+ error = -EPERM;
+ goto out_dput;
+ }
+
+ if ((fmode & FMODE_WRITE) && IS_IMMUTABLE(inode)) {
+ error = -EPERM;
+ goto out_dput;
+ }
+
+ /* Can't write directories. */
+ if (S_ISDIR(inode->i_mode) && (fmode & FMODE_WRITE)) {
+ error = -EISDIR;
+ goto out_dput;
+ }
+
+ fd = get_unused_fd_flags(0);
+ if (fd < 0) {
+ error = fd;
+ goto out_dput;
+ }
+
+ path.mnt = parfilp->f_path.mnt;
+ path.dentry = dentry;
+ filp = dentry_open(&path, hreq->oflags, cred);
+ dput(dentry);
+ if (IS_ERR(filp)) {
+ put_unused_fd(fd);
+ return PTR_ERR(filp);
+ }
+
+ if (S_ISREG(inode->i_mode)) {
+ filp->f_flags |= O_NOATIME;
+ filp->f_mode |= FMODE_NOCMTIME;
+ }
+
+ fd_install(fd, filp);
+ return fd;
+
+ out_dput:
+ dput(dentry);
+ return error;
+}
+
+int
+xfs_readlink_by_handle(
+ struct file *parfilp,
+ xfs_fsop_handlereq_t *hreq)
+{
+ struct dentry *dentry;
+ __u32 olen;
+ int error;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ dentry = xfs_handlereq_to_dentry(parfilp, hreq);
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+
+ /* Restrict this handle operation to symlinks only. */
+ if (!d_is_symlink(dentry)) {
+ error = -EINVAL;
+ goto out_dput;
+ }
+
+ if (copy_from_user(&olen, hreq->ohandlen, sizeof(__u32))) {
+ error = -EFAULT;
+ goto out_dput;
+ }
+
+ error = vfs_readlink(dentry, hreq->ohandle, olen);
+
+ out_dput:
+ dput(dentry);
+ return error;
+}
+
+/*
+ * Format an attribute and copy it out to the user's buffer.
+ * Take care to check values and protect against them changing later,
+ * we may be reading them directly out of a user buffer.
+ */
+static void
+xfs_ioc_attr_put_listent(
+ struct xfs_attr_list_context *context,
+ int flags,
+ unsigned char *name,
+ int namelen,
+ void *value,
+ int valuelen)
+{
+ struct xfs_attrlist *alist = context->buffer;
+ struct xfs_attrlist_ent *aep;
+ int arraytop;
+
+ ASSERT(!context->seen_enough);
+ ASSERT(context->count >= 0);
+ ASSERT(context->count < (ATTR_MAX_VALUELEN/8));
+ ASSERT(context->firstu >= sizeof(*alist));
+ ASSERT(context->firstu <= context->bufsize);
+
+ /*
+ * Only list entries in the right namespace.
+ */
+ if (context->attr_filter != (flags & XFS_ATTR_NSP_ONDISK_MASK))
+ return;
+
+ arraytop = sizeof(*alist) +
+ context->count * sizeof(alist->al_offset[0]);
+
+ /* decrement by the actual bytes used by the attr */
+ context->firstu -= round_up(offsetof(struct xfs_attrlist_ent, a_name) +
+ namelen + 1, sizeof(uint32_t));
+ if (context->firstu < arraytop) {
+ trace_xfs_attr_list_full(context);
+ alist->al_more = 1;
+ context->seen_enough = 1;
+ return;
+ }
+
+ aep = context->buffer + context->firstu;
+ aep->a_valuelen = valuelen;
+ memcpy(aep->a_name, name, namelen);
+ aep->a_name[namelen] = 0;
+ alist->al_offset[context->count++] = context->firstu;
+ alist->al_count = context->count;
+ trace_xfs_attr_list_add(context);
+}
+
+static unsigned int
+xfs_attr_filter(
+ u32 ioc_flags)
+{
+ if (ioc_flags & XFS_IOC_ATTR_ROOT)
+ return XFS_ATTR_ROOT;
+ if (ioc_flags & XFS_IOC_ATTR_SECURE)
+ return XFS_ATTR_SECURE;
+ return 0;
+}
+
+static inline enum xfs_attr_update
+xfs_xattr_flags(
+ u32 ioc_flags,
+ void *value)
+{
+ if (!value)
+ return XFS_ATTRUPDATE_REMOVE;
+ if (ioc_flags & XFS_IOC_ATTR_CREATE)
+ return XFS_ATTRUPDATE_CREATE;
+ if (ioc_flags & XFS_IOC_ATTR_REPLACE)
+ return XFS_ATTRUPDATE_REPLACE;
+ return XFS_ATTRUPDATE_UPSERT;
+}
+
+int
+xfs_ioc_attr_list(
+ struct xfs_inode *dp,
+ void __user *ubuf,
+ size_t bufsize,
+ int flags,
+ struct xfs_attrlist_cursor __user *ucursor)
+{
+ struct xfs_attr_list_context context = { };
+ struct xfs_attrlist *alist;
+ void *buffer;
+ int error;
+
+ if (bufsize < sizeof(struct xfs_attrlist) ||
+ bufsize > XFS_XATTR_LIST_MAX)
+ return -EINVAL;
+
+ /*
+ * Reject flags, only allow namespaces.
+ */
+ if (flags & ~(XFS_IOC_ATTR_ROOT | XFS_IOC_ATTR_SECURE))
+ return -EINVAL;
+ if (flags == (XFS_IOC_ATTR_ROOT | XFS_IOC_ATTR_SECURE))
+ return -EINVAL;
+
+ /*
+ * Validate the cursor.
+ */
+ if (copy_from_user(&context.cursor, ucursor, sizeof(context.cursor)))
+ return -EFAULT;
+ if (context.cursor.pad1 || context.cursor.pad2)
+ return -EINVAL;
+ if (!context.cursor.initted &&
+ (context.cursor.hashval || context.cursor.blkno ||
+ context.cursor.offset))
+ return -EINVAL;
+
+ buffer = kvzalloc(bufsize, GFP_KERNEL);
+ if (!buffer)
+ return -ENOMEM;
+
+ /*
+ * Initialize the output buffer.
+ */
+ context.dp = dp;
+ context.resynch = 1;
+ context.attr_filter = xfs_attr_filter(flags);
+ context.buffer = buffer;
+ context.bufsize = round_down(bufsize, sizeof(uint32_t));
+ context.firstu = context.bufsize;
+ context.put_listent = xfs_ioc_attr_put_listent;
+
+ alist = context.buffer;
+ alist->al_count = 0;
+ alist->al_more = 0;
+ alist->al_offset[0] = context.bufsize;
+
+ error = xfs_attr_list(&context);
+ if (error)
+ goto out_free;
+
+ if (copy_to_user(ubuf, buffer, bufsize) ||
+ copy_to_user(ucursor, &context.cursor, sizeof(context.cursor)))
+ error = -EFAULT;
+out_free:
+ kvfree(buffer);
+ return error;
+}
+
+int
+xfs_attrlist_by_handle(
+ struct file *parfilp,
+ struct xfs_fsop_attrlist_handlereq __user *p)
+{
+ struct xfs_fsop_attrlist_handlereq al_hreq;
+ struct dentry *dentry;
+ int error = -ENOMEM;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ if (copy_from_user(&al_hreq, p, sizeof(al_hreq)))
+ return -EFAULT;
+
+ dentry = xfs_handlereq_to_dentry(parfilp, &al_hreq.hreq);
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+
+ error = xfs_ioc_attr_list(XFS_I(d_inode(dentry)), al_hreq.buffer,
+ al_hreq.buflen, al_hreq.flags, &p->pos);
+ dput(dentry);
+ return error;
+}
+
+static int
+xfs_attrmulti_attr_get(
+ struct inode *inode,
+ unsigned char *name,
+ unsigned char __user *ubuf,
+ uint32_t *len,
+ uint32_t flags)
+{
+ struct xfs_da_args args = {
+ .dp = XFS_I(inode),
+ .attr_filter = xfs_attr_filter(flags),
+ .name = name,
+ .namelen = strlen(name),
+ .valuelen = *len,
+ };
+ int error;
+
+ if (*len > XFS_XATTR_SIZE_MAX)
+ return -EINVAL;
+
+ error = xfs_attr_get(&args);
+ if (error)
+ goto out_kfree;
+
+ *len = args.valuelen;
+ if (copy_to_user(ubuf, args.value, args.valuelen))
+ error = -EFAULT;
+
+out_kfree:
+ kvfree(args.value);
+ return error;
+}
+
+static int
+xfs_attrmulti_attr_set(
+ struct inode *inode,
+ unsigned char *name,
+ const unsigned char __user *ubuf,
+ uint32_t len,
+ uint32_t flags)
+{
+ struct xfs_da_args args = {
+ .dp = XFS_I(inode),
+ .attr_filter = xfs_attr_filter(flags),
+ .name = name,
+ .namelen = strlen(name),
+ };
+ int error;
+
+ if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
+ return -EPERM;
+
+ if (ubuf) {
+ if (len > XFS_XATTR_SIZE_MAX)
+ return -EINVAL;
+ args.value = memdup_user(ubuf, len);
+ if (IS_ERR(args.value))
+ return PTR_ERR(args.value);
+ args.valuelen = len;
+ }
+
+ error = xfs_attr_change(&args, xfs_xattr_flags(flags, args.value));
+ if (!error && (flags & XFS_IOC_ATTR_ROOT))
+ xfs_forget_acl(inode, name);
+ kfree(args.value);
+ return error;
+}
+
+int
+xfs_ioc_attrmulti_one(
+ struct file *parfilp,
+ struct inode *inode,
+ uint32_t opcode,
+ void __user *uname,
+ void __user *value,
+ uint32_t *len,
+ uint32_t flags)
+{
+ unsigned char *name;
+ int error;
+
+ if ((flags & XFS_IOC_ATTR_ROOT) && (flags & XFS_IOC_ATTR_SECURE))
+ return -EINVAL;
+
+ name = strndup_user(uname, MAXNAMELEN);
+ if (IS_ERR(name))
+ return PTR_ERR(name);
+
+ switch (opcode) {
+ case ATTR_OP_GET:
+ error = xfs_attrmulti_attr_get(inode, name, value, len, flags);
+ break;
+ case ATTR_OP_REMOVE:
+ value = NULL;
+ *len = 0;
+ fallthrough;
+ case ATTR_OP_SET:
+ error = mnt_want_write_file(parfilp);
+ if (error)
+ break;
+ error = xfs_attrmulti_attr_set(inode, name, value, *len, flags);
+ mnt_drop_write_file(parfilp);
+ break;
+ default:
+ error = -EINVAL;
+ break;
+ }
+
+ kfree(name);
+ return error;
+}
+
+int
+xfs_attrmulti_by_handle(
+ struct file *parfilp,
+ void __user *arg)
+{
+ int error;
+ xfs_attr_multiop_t *ops;
+ xfs_fsop_attrmulti_handlereq_t am_hreq;
+ struct dentry *dentry;
+ unsigned int i, size;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ if (copy_from_user(&am_hreq, arg, sizeof(xfs_fsop_attrmulti_handlereq_t)))
+ return -EFAULT;
+
+ /* overflow check */
+ if (am_hreq.opcount >= INT_MAX / sizeof(xfs_attr_multiop_t))
+ return -E2BIG;
+
+ dentry = xfs_handlereq_to_dentry(parfilp, &am_hreq.hreq);
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+
+ error = -E2BIG;
+ size = am_hreq.opcount * sizeof(xfs_attr_multiop_t);
+ if (!size || size > 16 * PAGE_SIZE)
+ goto out_dput;
+
+ ops = memdup_user(am_hreq.ops, size);
+ if (IS_ERR(ops)) {
+ error = PTR_ERR(ops);
+ goto out_dput;
+ }
+
+ error = 0;
+ for (i = 0; i < am_hreq.opcount; i++) {
+ ops[i].am_error = xfs_ioc_attrmulti_one(parfilp,
+ d_inode(dentry), ops[i].am_opcode,
+ ops[i].am_attrname, ops[i].am_attrvalue,
+ &ops[i].am_length, ops[i].am_flags);
+ }
+
+ if (copy_to_user(am_hreq.ops, ops, size))
+ error = -EFAULT;
+
+ kfree(ops);
+ out_dput:
+ dput(dentry);
+ return error;
+}
+
+struct xfs_getparents_ctx {
+ struct xfs_attr_list_context context;
+ struct xfs_getparents_by_handle gph;
+
+ /* File to target */
+ struct xfs_inode *ip;
+
+ /* Internal buffer where we format records */
+ void *krecords;
+
+ /* Last record filled out */
+ struct xfs_getparents_rec *lastrec;
+
+ unsigned int count;
+};
+
+static inline unsigned int
+xfs_getparents_rec_sizeof(
+ unsigned int namelen)
+{
+ return round_up(sizeof(struct xfs_getparents_rec) + namelen + 1,
+ sizeof(uint64_t));
+}
+
+static void
+xfs_getparents_put_listent(
+ struct xfs_attr_list_context *context,
+ int flags,
+ unsigned char *name,
+ int namelen,
+ void *value,
+ int valuelen)
+{
+ struct xfs_getparents_ctx *gpx =
+ container_of(context, struct xfs_getparents_ctx, context);
+ struct xfs_inode *ip = context->dp;
+ struct xfs_mount *mp = ip->i_mount;
+ struct xfs_getparents *gp = &gpx->gph.gph_request;
+ struct xfs_getparents_rec *gpr = gpx->krecords + context->firstu;
+ unsigned short reclen =
+ xfs_getparents_rec_sizeof(namelen);
+ xfs_ino_t ino;
+ uint32_t gen;
+ int error;
+
+ if (!(flags & XFS_ATTR_PARENT))
+ return;
+
+ error = xfs_parent_from_attr(mp, flags, name, namelen, value, valuelen,
+ &ino, &gen);
+ if (error) {
+ xfs_inode_mark_sick(ip, XFS_SICK_INO_PARENT);
+ context->seen_enough = -EFSCORRUPTED;
+ return;
+ }
+
+ /*
+ * We found a parent pointer, but we've filled up the buffer. Signal
+ * to the caller that we did /not/ reach the end of the parent pointer
+ * recordset.
+ */
+ if (context->firstu > context->bufsize - reclen) {
+ context->seen_enough = 1;
+ return;
+ }
+
+ /* Format the parent pointer directly into the caller buffer. */
+ gpr->gpr_reclen = reclen;
+ xfs_filehandle_init(mp, ino, gen, &gpr->gpr_parent);
+ memcpy(gpr->gpr_name, name, namelen);
+ gpr->gpr_name[namelen] = 0;
+
+ trace_xfs_getparents_put_listent(ip, gp, context, gpr);
+
+ context->firstu += reclen;
+ gpx->count++;
+ gpx->lastrec = gpr;
+}
+
+/* Expand the last record to fill the rest of the caller's buffer. */
+static inline void
+xfs_getparents_expand_lastrec(
+ struct xfs_getparents_ctx *gpx)
+{
+ struct xfs_getparents *gp = &gpx->gph.gph_request;
+ struct xfs_getparents_rec *gpr = gpx->lastrec;
+
+ if (!gpx->lastrec)
+ gpr = gpx->krecords;
+
+ gpr->gpr_reclen = gp->gp_bufsize - ((void *)gpr - gpx->krecords);
+
+ trace_xfs_getparents_expand_lastrec(gpx->ip, gp, &gpx->context, gpr);
+}
+
+/* Retrieve the parent pointers for a given inode. */
+STATIC int
+xfs_getparents(
+ struct xfs_getparents_ctx *gpx)
+{
+ struct xfs_getparents *gp = &gpx->gph.gph_request;
+ struct xfs_inode *ip = gpx->ip;
+ struct xfs_mount *mp = ip->i_mount;
+ size_t bufsize;
+ int error;
+
+ /* Check size of buffer requested by user */
+ if (gp->gp_bufsize > XFS_XATTR_LIST_MAX)
+ return -ENOMEM;
+ if (gp->gp_bufsize < xfs_getparents_rec_sizeof(1))
+ return -EINVAL;
+
+ if (gp->gp_iflags & ~XFS_GETPARENTS_IFLAGS_ALL)
+ return -EINVAL;
+ if (gp->gp_reserved)
+ return -EINVAL;
+
+ bufsize = round_down(gp->gp_bufsize, sizeof(uint64_t));
+ gpx->krecords = kvzalloc(bufsize, GFP_KERNEL);
+ if (!gpx->krecords) {
+ bufsize = min(bufsize, PAGE_SIZE);
+ gpx->krecords = kvzalloc(bufsize, GFP_KERNEL);
+ if (!gpx->krecords)
+ return -ENOMEM;
+ }
+
+ gpx->context.dp = ip;
+ gpx->context.resynch = 1;
+ gpx->context.put_listent = xfs_getparents_put_listent;
+ gpx->context.bufsize = bufsize;
+ /* firstu is used to track the bytes filled in the buffer */
+ gpx->context.firstu = 0;
+
+ /* Copy the cursor provided by caller */
+ memcpy(&gpx->context.cursor, &gp->gp_cursor,
+ sizeof(struct xfs_attrlist_cursor));
+ gpx->count = 0;
+ gp->gp_oflags = 0;
+
+ trace_xfs_getparents_begin(ip, gp, &gpx->context.cursor);
+
+ error = xfs_attr_list(&gpx->context);
+ if (error)
+ goto out_free_buf;
+ if (gpx->context.seen_enough < 0) {
+ error = gpx->context.seen_enough;
+ goto out_free_buf;
+ }
+ xfs_getparents_expand_lastrec(gpx);
+
+ /* Update the caller with the current cursor position */
+ memcpy(&gp->gp_cursor, &gpx->context.cursor,
+ sizeof(struct xfs_attrlist_cursor));
+
+ /* Is this the root directory? */
+ if (ip->i_ino == mp->m_sb.sb_rootino)
+ gp->gp_oflags |= XFS_GETPARENTS_OFLAG_ROOT;
+
+ if (gpx->context.seen_enough == 0) {
+ /*
+ * If we did not run out of buffer space, then we reached the
+ * end of the pptr recordset, so set the DONE flag.
+ */
+ gp->gp_oflags |= XFS_GETPARENTS_OFLAG_DONE;
+ } else if (gpx->count == 0) {
+ /*
+ * If we ran out of buffer space before copying any parent
+ * pointers at all, the caller's buffer was too short. Tell
+ * userspace that, erm, the message is too long.
+ */
+ error = -EMSGSIZE;
+ goto out_free_buf;
+ }
+
+ trace_xfs_getparents_end(ip, gp, &gpx->context.cursor);
+
+ ASSERT(gpx->context.firstu <= gpx->gph.gph_request.gp_bufsize);
+
+ /* Copy the records to userspace. */
+ if (copy_to_user(u64_to_user_ptr(gpx->gph.gph_request.gp_buffer),
+ gpx->krecords, gpx->context.firstu))
+ error = -EFAULT;
+
+out_free_buf:
+ kvfree(gpx->krecords);
+ gpx->krecords = NULL;
+ return error;
+}
+
+/* Retrieve the parents of this file and pass them back to userspace. */
+int
+xfs_ioc_getparents(
+ struct file *file,
+ struct xfs_getparents __user *ureq)
+{
+ struct xfs_getparents_ctx gpx = {
+ .ip = XFS_I(file_inode(file)),
+ };
+ struct xfs_getparents *kreq = &gpx.gph.gph_request;
+ struct xfs_mount *mp = gpx.ip->i_mount;
+ int error;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ if (!xfs_has_parent(mp))
+ return -EOPNOTSUPP;
+ if (copy_from_user(kreq, ureq, sizeof(*kreq)))
+ return -EFAULT;
+
+ error = xfs_getparents(&gpx);
+ if (error)
+ return error;
+
+ if (copy_to_user(ureq, kreq, sizeof(*kreq)))
+ return -EFAULT;
+
+ return 0;
+}
+
+/* Retrieve the parents of this file handle and pass them back to userspace. */
+int
+xfs_ioc_getparents_by_handle(
+ struct file *file,
+ struct xfs_getparents_by_handle __user *ureq)
+{
+ struct xfs_getparents_ctx gpx = { };
+ struct xfs_inode *ip = XFS_I(file_inode(file));
+ struct xfs_mount *mp = ip->i_mount;
+ struct xfs_getparents_by_handle *kreq = &gpx.gph;
+ struct xfs_handle *handle = &kreq->gph_handle;
+ int error;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ if (!xfs_has_parent(mp))
+ return -EOPNOTSUPP;
+ if (copy_from_user(kreq, ureq, sizeof(*kreq)))
+ return -EFAULT;
+
+ /*
+ * We don't use exportfs_decode_fh because it does too much work here.
+ * If the handle refers to a directory, the exportfs code will walk
+ * upwards through the directory tree to connect the dentries to the
+ * root directory dentry. For GETPARENTS we don't care about that
+ * because we're not actually going to open a file descriptor; we only
+ * want to open an inode and read its parent pointers.
+ *
+ * Note that xfs_scrub uses GETPARENTS to log that it will try to fix a
+ * corrupted file's metadata. For this usecase we would really rather
+ * userspace single-step the path reconstruction to avoid loops or
+ * other strange things if the directory tree is corrupt.
+ */
+ gpx.ip = xfs_khandle_to_inode(file, handle);
+ if (IS_ERR(gpx.ip))
+ return PTR_ERR(gpx.ip);
+
+ error = xfs_getparents(&gpx);
+ if (error)
+ goto out_rele;
+
+ if (copy_to_user(ureq, kreq, sizeof(*kreq)))
+ error = -EFAULT;
+
+out_rele:
+ xfs_irele(gpx.ip);
+ return error;
+}