| 1 | /* $Id: lnkops.c 98103 2023-01-17 14:15:46Z vboxsync $ */
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| 2 | /** @file
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| 3 | * vboxsf - VBox Linux Shared Folders VFS, operations for symbolic links.
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| 4 | */
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| 5 |
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| 6 | /*
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| 7 | * Copyright (C) 2010-2023 Oracle and/or its affiliates.
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| 8 | *
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| 9 | * Permission is hereby granted, free of charge, to any person
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| 10 | * obtaining a copy of this software and associated documentation
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| 11 | * files (the "Software"), to deal in the Software without
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| 12 | * restriction, including without limitation the rights to use,
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| 13 | * copy, modify, merge, publish, distribute, sublicense, and/or sell
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| 14 | * copies of the Software, and to permit persons to whom the
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| 15 | * Software is furnished to do so, subject to the following
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| 16 | * conditions:
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| 17 | *
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| 18 | * The above copyright notice and this permission notice shall be
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| 19 | * included in all copies or substantial portions of the Software.
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| 20 | *
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| 21 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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| 22 | * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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| 23 | * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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| 24 | * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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| 25 | * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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| 26 | * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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| 27 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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| 28 | * OTHER DEALINGS IN THE SOFTWARE.
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| 29 | */
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| 30 |
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| 31 |
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| 32 | /*********************************************************************************************************************************
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| 33 | * Header Files *
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| 34 | *********************************************************************************************************************************/
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| 35 | #include "vfsmod.h"
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| 36 |
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| 37 |
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| 38 | /**
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| 39 | * Converts error codes as best we can.
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| 40 | */
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| 41 | DECLINLINE(int) vbsf_convert_symlink_error(int vrc)
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| 42 | {
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| 43 | if ( vrc == VERR_IS_A_DIRECTORY
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| 44 | || vrc == VERR_IS_A_FIFO
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| 45 | || vrc == VERR_IS_A_FILE
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| 46 | || vrc == VERR_IS_A_BLOCK_DEVICE
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| 47 | || vrc == VERR_IS_A_CHAR_DEVICE
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| 48 | || vrc == VERR_IS_A_SOCKET
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| 49 | || vrc == VERR_NOT_SYMLINK)
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| 50 | return -EINVAL;
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| 51 | if (vrc == VERR_PATH_NOT_FOUND)
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| 52 | return -ENOTDIR;
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| 53 | if (vrc == VERR_FILE_NOT_FOUND)
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| 54 | return -ENOENT;
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| 55 | return -EPROTO;
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| 56 | }
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| 57 |
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| 58 |
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| 59 | /**
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| 60 | * Does the NLS conversion of the symlink target.
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| 61 | */
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| 62 | static int vbsf_symlink_nls_convert_slow(struct vbsf_super_info *pSuperInfo, char *pszTarget, size_t cbTargetBuf)
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| 63 | {
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| 64 | int rc;
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| 65 | size_t const cchUtf8 = RTStrNLen(pszTarget, cbTargetBuf);
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| 66 | if (cchUtf8 < cbTargetBuf) {
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| 67 | /*
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| 68 | * If the target is short and there is a lot of space left in the target
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| 69 | * buffer (typically PAGE_SIZE in size), we move the input to the end
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| 70 | * instead of allocating a temporary buffer for it. This works because
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| 71 | * there shouldn't be anything that is more than 8x worse than UTF-8
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| 72 | * when it comes to efficiency.
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| 73 | */
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| 74 | char *pszFree = NULL;
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| 75 | char *pszUtf8;
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| 76 | if (cchUtf8 - 1 <= cbTargetBuf / 8) {
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| 77 | pszUtf8 = &pszTarget[cbTargetBuf - cchUtf8 - 1];
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| 78 | cbTargetBuf -= cchUtf8 - 1;
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| 79 | } else {
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| 80 | pszFree = pszUtf8 = kmalloc(cchUtf8 + 1, GFP_KERNEL);
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| 81 | if (RT_UNLIKELY(!pszUtf8)) {
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| 82 | LogRelMax(50, ("vbsf_symlink_nls_convert_slow: failed to allocate %u bytes\n", cchUtf8 + 1));
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| 83 | return -ENOMEM;
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| 84 | }
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| 85 | }
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| 86 | memcpy(pszUtf8, pszTarget, cchUtf8);
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| 87 | pszUtf8[cchUtf8] = '\0';
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| 88 |
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| 89 | rc = vbsf_nlscpy(pSuperInfo, pszTarget, cbTargetBuf, pszUtf8, cchUtf8);
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| 90 | if (pszFree)
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| 91 | kfree(pszFree);
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| 92 | } else {
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| 93 | SFLOGFLOW(("vbsf_symlink_nls_convert_slow: Impossible! Unterminated target!\n"));
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| 94 | rc = -ENAMETOOLONG;
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| 95 | }
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| 96 | return rc;
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| 97 | }
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| 98 |
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| 99 |
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| 100 | /**
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| 101 | * Does NLS conversion if needed.
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| 102 | */
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| 103 | DECLINLINE(int) vbsf_symlink_nls_convert(struct vbsf_super_info *pSuperInfo, char *pszTarget, size_t cbTargetBuf)
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| 104 | {
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| 105 | if (pSuperInfo->fNlsIsUtf8)
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| 106 | return 0;
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| 107 | return vbsf_symlink_nls_convert_slow(pSuperInfo, pszTarget, cbTargetBuf);
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| 108 | }
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| 109 |
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| 110 | #if RTLNX_VER_MIN(4,5,0)
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| 111 |
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| 112 | /**
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| 113 | * Get symbolic link.
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| 114 | */
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| 115 | static const char *vbsf_get_link(struct dentry *dentry, struct inode *inode, struct delayed_call *done)
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| 116 | {
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| 117 | char *pszTarget;
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| 118 | if (dentry) {
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| 119 | pszTarget = (char *)kzalloc(PAGE_SIZE, GFP_KERNEL);
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| 120 | if (pszTarget) {
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| 121 | struct vbsf_super_info *pSuperInfo = VBSF_GET_SUPER_INFO(inode->i_sb);
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| 122 | struct vbsf_inode_info *sf_i = VBSF_GET_INODE_INFO(inode);
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| 123 | int rc = VbglR0SfHostReqReadLinkContigSimple(pSuperInfo->map.root, sf_i->path->String.ach, sf_i->path->u16Length,
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| 124 | pszTarget, virt_to_phys(pszTarget), RT_MIN(PATH_MAX, PAGE_SIZE - 1));
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| 125 | if (RT_SUCCESS(rc)) {
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| 126 | pszTarget[PAGE_SIZE - 1] = '\0';
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| 127 | SFLOGFLOW(("vbsf_get_link: %s -> %s\n", sf_i->path->String.ach, pszTarget));
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| 128 | rc = vbsf_symlink_nls_convert(pSuperInfo, pszTarget, PAGE_SIZE);
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| 129 | if (rc == 0) {
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| 130 | vbsf_dentry_chain_increase_ttl(dentry);
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| 131 | set_delayed_call(done, kfree_link, pszTarget);
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| 132 | return pszTarget;
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| 133 | }
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| 134 | } else {
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| 135 | SFLOGFLOW(("vbsf_get_link: VbglR0SfHostReqReadLinkContigSimple failed on '%s': %Rrc\n",
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| 136 | sf_i->path->String.ach, rc));
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| 137 | }
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| 138 | kfree(pszTarget);
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| 139 | pszTarget = ERR_PTR(vbsf_convert_symlink_error(rc));
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| 140 | } else
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| 141 | pszTarget = ERR_PTR(-ENOMEM);
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| 142 | } else
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| 143 | pszTarget = ERR_PTR(-ECHILD);
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| 144 | return pszTarget;
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| 145 | }
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| 146 |
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| 147 | #else /* < 4.5 */
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| 148 |
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| 149 | # if RTLNX_VER_MAX(2,6,8)
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| 150 | /**
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| 151 | * Reads the link into the given buffer.
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| 152 | */
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| 153 | static int vbsf_readlink(struct dentry *dentry, char *buffer, int len)
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| 154 | {
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| 155 | int rc;
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| 156 | char *pszTarget = (char *)get_zeroed_page(GFP_KERNEL);
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| 157 | if (pszTarget) {
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| 158 | struct inode *inode = dentry->d_inode;
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| 159 | struct vbsf_super_info *pSuperInfo = VBSF_GET_SUPER_INFO(inode->i_sb);
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| 160 | struct vbsf_inode_info *sf_i = VBSF_GET_INODE_INFO(inode);
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| 161 | rc = VbglR0SfHostReqReadLinkContigSimple(pSuperInfo->map.root, sf_i->path->String.ach, sf_i->path->u16Length,
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| 162 | pszTarget, virt_to_phys(pszTarget), RT_MIN(PATH_MAX, PAGE_SIZE - 1));
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| 163 | if (RT_SUCCESS(rc)) {
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| 164 | pszTarget[PAGE_SIZE - 1] = '\0';
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| 165 | SFLOGFLOW(("vbsf_readlink: %s -> %*s\n", sf_i->path->String.ach, pszTarget));
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| 166 | rc = vbsf_symlink_nls_convert(pSuperInfo, pszTarget, PAGE_SIZE);
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| 167 | if (rc == 0) {
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| 168 | vbsf_dentry_chain_increase_ttl(dentry);
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| 169 | rc = vfs_readlink(dentry, buffer, len, pszTarget);
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| 170 | }
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| 171 | } else {
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| 172 | SFLOGFLOW(("vbsf_readlink: VbglR0SfHostReqReadLinkContigSimple failed on '%s': %Rrc\n", sf_i->path->String.ach, rc));
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| 173 | rc = vbsf_convert_symlink_error(rc);
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| 174 | }
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| 175 | free_page((unsigned long)pszTarget);
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| 176 | } else
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| 177 | rc = -ENOMEM;
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| 178 | return rc;
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| 179 | }
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| 180 | # endif /* < 2.6.8 */
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| 181 |
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| 182 | /**
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| 183 | * Follow link in dentry.
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| 184 | */
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| 185 | # if RTLNX_VER_MIN(4,2,0)
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| 186 | static const char *vbsf_follow_link(struct dentry *dentry, void **cookie)
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| 187 | # elif RTLNX_VER_MIN(2,6,13)
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| 188 | static void *vbsf_follow_link(struct dentry *dentry, struct nameidata *nd)
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| 189 | # else
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| 190 | static int vbsf_follow_link(struct dentry *dentry, struct nameidata *nd)
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| 191 | # endif
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| 192 | {
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| 193 | int rc;
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| 194 | char *pszTarget = (char *)get_zeroed_page(GFP_KERNEL);
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| 195 | if (pszTarget) {
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| 196 | struct inode *inode = dentry->d_inode;
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| 197 | struct vbsf_super_info *pSuperInfo = VBSF_GET_SUPER_INFO(inode->i_sb);
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| 198 | struct vbsf_inode_info *sf_i = VBSF_GET_INODE_INFO(inode);
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| 199 |
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| 200 | rc = VbglR0SfHostReqReadLinkContigSimple(pSuperInfo->map.root, sf_i->path->String.ach, sf_i->path->u16Length,
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| 201 | pszTarget, virt_to_phys(pszTarget), RT_MIN(PATH_MAX, PAGE_SIZE - 1));
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| 202 | if (RT_SUCCESS(rc)) {
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| 203 | pszTarget[PAGE_SIZE - 1] = '\0';
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| 204 | SFLOGFLOW(("vbsf_follow_link: %s -> %s\n", sf_i->path->String.ach, pszTarget));
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| 205 | rc = vbsf_symlink_nls_convert(pSuperInfo, pszTarget, PAGE_SIZE);
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| 206 | if (rc == 0) {
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| 207 | /*
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| 208 | * Succeeded. For 2.6.8 and later the page gets associated
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| 209 | * with the caller-cookie or nameidata structure and freed
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| 210 | * later by vbsf_put_link(). On earlier kernels we have to
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| 211 | * call vfs_follow_link() which will try continue the walking
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| 212 | * using the buffer we pass it here.
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| 213 | */
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| 214 | vbsf_dentry_chain_increase_ttl(dentry);
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| 215 | # if RTLNX_VER_MIN(4,2,0)
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| 216 | *cookie = pszTarget;
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| 217 | return pszTarget;
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| 218 | # elif RTLNX_VER_MIN(2,6,8)
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| 219 | nd_set_link(nd, pszTarget);
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| 220 | # if RTLNX_VER_MIN(2,6,13)
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| 221 | return NULL;
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| 222 | # else
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| 223 | return 0;
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| 224 | # endif
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| 225 | # else /* < 2.6.8 */
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| 226 | rc = vfs_follow_link(nd, pszTarget);
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| 227 | free_page((unsigned long)pszTarget);
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| 228 | return rc;
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| 229 | # endif
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| 230 | }
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| 231 |
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| 232 | /*
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| 233 | * Failed.
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| 234 | */
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| 235 | } else {
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| 236 | LogFunc(("VbglR0SfReadLink failed, caller=%s, rc=%Rrc\n", __func__, rc));
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| 237 | rc = vbsf_convert_symlink_error(rc);
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| 238 | }
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| 239 | free_page((unsigned long)pszTarget);
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| 240 | } else {
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| 241 | rc = -ENOMEM;
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| 242 | }
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| 243 | # if RTLNX_VER_MIN(4,2,0)
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| 244 | *cookie = ERR_PTR(rc);
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| 245 | return (const char *)ERR_PTR(rc);
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| 246 | # elif RTLNX_VER_MIN(2,6,8)
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| 247 | nd_set_link(nd, (char *)ERR_PTR(rc));
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| 248 | # if RTLNX_VER_MIN(2,6,13)
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| 249 | return NULL;
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| 250 | # else
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| 251 | return 0;
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| 252 | # endif
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| 253 | # else /* < 2.6.8 */
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| 254 | return rc;
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| 255 | # endif /* < 2.6.8 */
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| 256 | }
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| 257 |
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| 258 | # if RTLNX_VER_MIN(2,6,8)
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| 259 | /**
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| 260 | * For freeing target link buffer allocated by vbsf_follow_link.
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| 261 | *
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| 262 | * For kernels before 2.6.8 memory isn't being kept around.
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| 263 | */
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| 264 | # if RTLNX_VER_MIN(4,2,0)
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| 265 | static void vbsf_put_link(struct inode *inode, void *cookie)
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| 266 | # elif RTLNX_VER_MIN(2,6,13)
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| 267 | static void vbsf_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
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| 268 | # else
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| 269 | static void vbsf_put_link(struct dentry *dentry, struct nameidata *nd)
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| 270 | # endif
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| 271 | {
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| 272 | # if RTLNX_VER_MIN(2,6,13)
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| 273 | char *page = cookie;
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| 274 | # else
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| 275 | char *page = nd_get_link(nd);
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| 276 | # endif
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| 277 | SFLOGFLOW(("vbsf_put_link: page=%p\n", page));
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| 278 | if (!IS_ERR(page))
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| 279 | free_page((unsigned long)page);
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| 280 | }
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| 281 | # endif /* >= 2.6.8 */
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| 282 |
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| 283 | #endif /* < 4.5.0 */
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| 284 |
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| 285 | /**
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| 286 | * Symlink inode operations.
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| 287 | */
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| 288 | struct inode_operations vbsf_lnk_iops = {
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| 289 | #if RTLNX_VER_MAX(4,10,0)
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| 290 | # if RTLNX_VER_MIN(2,6,8)
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| 291 | .readlink = generic_readlink,
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| 292 | # else
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| 293 | .readlink = vbsf_readlink,
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| 294 | # endif
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| 295 | #endif
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| 296 | #if RTLNX_VER_MIN(4,5,0)
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| 297 | .get_link = vbsf_get_link
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| 298 | #else
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| 299 | .follow_link = vbsf_follow_link,
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| 300 | # if RTLNX_VER_MIN(2,6,8)
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| 301 | .put_link = vbsf_put_link,
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| 302 | # endif
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| 303 | #endif
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| 304 | };
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| 305 |
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