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/* $Id: lnkops.c $ */
/** @file
* vboxsf - VBox Linux Shared Folders VFS, operations for symbolic links.
*/
/*
* Copyright (C) 2010-2022 Oracle and/or its affiliates.
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
/*********************************************************************************************************************************
* Header Files *
*********************************************************************************************************************************/
#include "vfsmod.h"
/**
* Converts error codes as best we can.
*/
DECLINLINE(int) vbsf_convert_symlink_error(int vrc)
{
if ( vrc == VERR_IS_A_DIRECTORY
|| vrc == VERR_IS_A_FIFO
|| vrc == VERR_IS_A_FILE
|| vrc == VERR_IS_A_BLOCK_DEVICE
|| vrc == VERR_IS_A_CHAR_DEVICE
|| vrc == VERR_IS_A_SOCKET
|| vrc == VERR_NOT_SYMLINK)
return -EINVAL;
if (vrc == VERR_PATH_NOT_FOUND)
return -ENOTDIR;
if (vrc == VERR_FILE_NOT_FOUND)
return -ENOENT;
return -EPROTO;
}
/**
* Does the NLS conversion of the symlink target.
*/
static int vbsf_symlink_nls_convert_slow(struct vbsf_super_info *pSuperInfo, char *pszTarget, size_t cbTargetBuf)
{
int rc;
size_t const cchUtf8 = RTStrNLen(pszTarget, cbTargetBuf);
if (cchUtf8 < cbTargetBuf) {
/*
* If the target is short and there is a lot of space left in the target
* buffer (typically PAGE_SIZE in size), we move the input to the end
* instead of allocating a temporary buffer for it. This works because
* there shouldn't be anything that is more than 8x worse than UTF-8
* when it comes to efficiency.
*/
char *pszFree = NULL;
char *pszUtf8;
if (cchUtf8 - 1 <= cbTargetBuf / 8) {
pszUtf8 = &pszTarget[cbTargetBuf - cchUtf8 - 1];
cbTargetBuf -= cchUtf8 - 1;
} else {
pszFree = pszUtf8 = kmalloc(cchUtf8 + 1, GFP_KERNEL);
if (RT_UNLIKELY(!pszUtf8)) {
LogRelMax(50, ("vbsf_symlink_nls_convert_slow: failed to allocate %u bytes\n", cchUtf8 + 1));
return -ENOMEM;
}
}
memcpy(pszUtf8, pszTarget, cchUtf8);
pszUtf8[cchUtf8] = '\0';
rc = vbsf_nlscpy(pSuperInfo, pszTarget, cbTargetBuf, pszUtf8, cchUtf8);
if (pszFree)
kfree(pszFree);
} else {
SFLOGFLOW(("vbsf_symlink_nls_convert_slow: Impossible! Unterminated target!\n"));
rc = -ENAMETOOLONG;
}
return rc;
}
/**
* Does NLS conversion if needed.
*/
DECLINLINE(int) vbsf_symlink_nls_convert(struct vbsf_super_info *pSuperInfo, char *pszTarget, size_t cbTargetBuf)
{
if (pSuperInfo->fNlsIsUtf8)
return 0;
return vbsf_symlink_nls_convert_slow(pSuperInfo, pszTarget, cbTargetBuf);
}
#if RTLNX_VER_MIN(4,5,0)
/**
* Get symbolic link.
*/
static const char *vbsf_get_link(struct dentry *dentry, struct inode *inode, struct delayed_call *done)
{
char *pszTarget;
if (dentry) {
pszTarget = (char *)kzalloc(PAGE_SIZE, GFP_KERNEL);
if (pszTarget) {
struct vbsf_super_info *pSuperInfo = VBSF_GET_SUPER_INFO(inode->i_sb);
struct vbsf_inode_info *sf_i = VBSF_GET_INODE_INFO(inode);
int rc = VbglR0SfHostReqReadLinkContigSimple(pSuperInfo->map.root, sf_i->path->String.ach, sf_i->path->u16Length,
pszTarget, virt_to_phys(pszTarget), RT_MIN(PATH_MAX, PAGE_SIZE - 1));
if (RT_SUCCESS(rc)) {
pszTarget[PAGE_SIZE - 1] = '\0';
SFLOGFLOW(("vbsf_get_link: %s -> %s\n", sf_i->path->String.ach, pszTarget));
rc = vbsf_symlink_nls_convert(pSuperInfo, pszTarget, PAGE_SIZE);
if (rc == 0) {
vbsf_dentry_chain_increase_ttl(dentry);
set_delayed_call(done, kfree_link, pszTarget);
return pszTarget;
}
} else {
SFLOGFLOW(("vbsf_get_link: VbglR0SfHostReqReadLinkContigSimple failed on '%s': %Rrc\n",
sf_i->path->String.ach, rc));
}
kfree(pszTarget);
pszTarget = ERR_PTR(vbsf_convert_symlink_error(rc));
} else
pszTarget = ERR_PTR(-ENOMEM);
} else
pszTarget = ERR_PTR(-ECHILD);
return pszTarget;
}
#else /* < 4.5 */
# if RTLNX_VER_MAX(2,6,8)
/**
* Reads the link into the given buffer.
*/
static int vbsf_readlink(struct dentry *dentry, char *buffer, int len)
{
int rc;
char *pszTarget = (char *)get_zeroed_page(GFP_KERNEL);
if (pszTarget) {
struct inode *inode = dentry->d_inode;
struct vbsf_super_info *pSuperInfo = VBSF_GET_SUPER_INFO(inode->i_sb);
struct vbsf_inode_info *sf_i = VBSF_GET_INODE_INFO(inode);
rc = VbglR0SfHostReqReadLinkContigSimple(pSuperInfo->map.root, sf_i->path->String.ach, sf_i->path->u16Length,
pszTarget, virt_to_phys(pszTarget), RT_MIN(PATH_MAX, PAGE_SIZE - 1));
if (RT_SUCCESS(rc)) {
pszTarget[PAGE_SIZE - 1] = '\0';
SFLOGFLOW(("vbsf_readlink: %s -> %*s\n", sf_i->path->String.ach, pszTarget));
rc = vbsf_symlink_nls_convert(pSuperInfo, pszTarget, PAGE_SIZE);
if (rc == 0) {
vbsf_dentry_chain_increase_ttl(dentry);
rc = vfs_readlink(dentry, buffer, len, pszTarget);
}
} else {
SFLOGFLOW(("vbsf_readlink: VbglR0SfHostReqReadLinkContigSimple failed on '%s': %Rrc\n", sf_i->path->String.ach, rc));
rc = vbsf_convert_symlink_error(rc);
}
free_page((unsigned long)pszTarget);
} else
rc = -ENOMEM;
return rc;
}
# endif /* < 2.6.8 */
/**
* Follow link in dentry.
*/
# if RTLNX_VER_MIN(4,2,0)
static const char *vbsf_follow_link(struct dentry *dentry, void **cookie)
# elif RTLNX_VER_MIN(2,6,13)
static void *vbsf_follow_link(struct dentry *dentry, struct nameidata *nd)
# else
static int vbsf_follow_link(struct dentry *dentry, struct nameidata *nd)
# endif
{
int rc;
char *pszTarget = (char *)get_zeroed_page(GFP_KERNEL);
if (pszTarget) {
struct inode *inode = dentry->d_inode;
struct vbsf_super_info *pSuperInfo = VBSF_GET_SUPER_INFO(inode->i_sb);
struct vbsf_inode_info *sf_i = VBSF_GET_INODE_INFO(inode);
rc = VbglR0SfHostReqReadLinkContigSimple(pSuperInfo->map.root, sf_i->path->String.ach, sf_i->path->u16Length,
pszTarget, virt_to_phys(pszTarget), RT_MIN(PATH_MAX, PAGE_SIZE - 1));
if (RT_SUCCESS(rc)) {
pszTarget[PAGE_SIZE - 1] = '\0';
SFLOGFLOW(("vbsf_follow_link: %s -> %s\n", sf_i->path->String.ach, pszTarget));
rc = vbsf_symlink_nls_convert(pSuperInfo, pszTarget, PAGE_SIZE);
if (rc == 0) {
/*
* Succeeded. For 2.6.8 and later the page gets associated
* with the caller-cookie or nameidata structure and freed
* later by vbsf_put_link(). On earlier kernels we have to
* call vfs_follow_link() which will try continue the walking
* using the buffer we pass it here.
*/
vbsf_dentry_chain_increase_ttl(dentry);
# if RTLNX_VER_MIN(4,2,0)
*cookie = pszTarget;
return pszTarget;
# elif RTLNX_VER_MIN(2,6,8)
nd_set_link(nd, pszTarget);
# if RTLNX_VER_MIN(2,6,13)
return NULL;
# else
return 0;
# endif
# else /* < 2.6.8 */
rc = vfs_follow_link(nd, pszTarget);
free_page((unsigned long)pszTarget);
return rc;
# endif
}
/*
* Failed.
*/
} else {
LogFunc(("VbglR0SfReadLink failed, caller=%s, rc=%Rrc\n", __func__, rc));
rc = vbsf_convert_symlink_error(rc);
}
free_page((unsigned long)pszTarget);
} else {
rc = -ENOMEM;
}
# if RTLNX_VER_MIN(4,2,0)
*cookie = ERR_PTR(rc);
return (const char *)ERR_PTR(rc);
# elif RTLNX_VER_MIN(2,6,8)
nd_set_link(nd, (char *)ERR_PTR(rc));
# if RTLNX_VER_MIN(2,6,13)
return NULL;
# else
return 0;
# endif
# else /* < 2.6.8 */
return rc;
# endif /* < 2.6.8 */
}
# if RTLNX_VER_MIN(2,6,8)
/**
* For freeing target link buffer allocated by vbsf_follow_link.
*
* For kernels before 2.6.8 memory isn't being kept around.
*/
# if RTLNX_VER_MIN(4,2,0)
static void vbsf_put_link(struct inode *inode, void *cookie)
# elif RTLNX_VER_MIN(2,6,13)
static void vbsf_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
# else
static void vbsf_put_link(struct dentry *dentry, struct nameidata *nd)
# endif
{
# if RTLNX_VER_MIN(2,6,13)
char *page = cookie;
# else
char *page = nd_get_link(nd);
# endif
SFLOGFLOW(("vbsf_put_link: page=%p\n", page));
if (!IS_ERR(page))
free_page((unsigned long)page);
}
# endif /* >= 2.6.8 */
#endif /* < 4.5.0 */
/**
* Symlink inode operations.
*/
struct inode_operations vbsf_lnk_iops = {
#if RTLNX_VER_MAX(4,10,0)
# if RTLNX_VER_MIN(2,6,8)
.readlink = generic_readlink,
# else
.readlink = vbsf_readlink,
# endif
#endif
#if RTLNX_VER_MIN(4,5,0)
.get_link = vbsf_get_link
#else
.follow_link = vbsf_follow_link,
# if RTLNX_VER_MIN(2,6,8)
.put_link = vbsf_put_link,
# endif
#endif
};
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