| 1 | /* $Id: lnkops.c 77529 2019-03-01 14:13:40Z 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) 2010-2019 Oracle Corporation
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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 | #include "vfsmod.h"
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| 32 |
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| 33 | #if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 8) /* no generic_readlink() before 2.6.8 */
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| 34 |
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| 35 | # if LINUX_VERSION_CODE < KERNEL_VERSION(4, 5, 0)
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| 36 |
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| 37 | # if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 2, 0)
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| 38 | static const char *vbsf_follow_link(struct dentry *dentry, void **cookie)
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| 39 | # elif LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 13)
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| 40 | static void *vbsf_follow_link(struct dentry *dentry, struct nameidata *nd)
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| 41 | # else
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| 42 | static int vbsf_follow_link(struct dentry *dentry, struct nameidata *nd)
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| 43 | # endif
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| 44 | {
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| 45 | struct inode *inode = dentry->d_inode;
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| 46 | struct vbsf_super_info *sf_g = VBSF_GET_SUPER_INFO(inode->i_sb);
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| 47 | struct sf_inode_info *sf_i = GET_INODE_INFO(inode);
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| 48 | int error = -ENOMEM;
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| 49 | char *path = (char *)get_zeroed_page(GFP_KERNEL);
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| 50 | int rc;
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| 51 |
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| 52 | if (path) {
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| 53 | error = 0;
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| 54 | rc = VbglR0SfReadLink(&g_SfClient, &sf_g->map, sf_i->path,
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| 55 | PATH_MAX, path);
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| 56 | if (RT_FAILURE(rc)) {
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| 57 | LogFunc(("VbglR0SfReadLink failed, caller=%s, rc=%Rrc\n", __func__, rc));
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| 58 | free_page((unsigned long)path);
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| 59 | error = -EPROTO;
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| 60 | }
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| 61 | }
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| 62 | # if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 2, 0)
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| 63 | return error ? ERR_PTR(error) : (*cookie = path);
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| 64 | # else
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| 65 | nd_set_link(nd, error ? ERR_PTR(error) : path);
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| 66 | # if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 13)
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| 67 | return NULL;
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| 68 | # else
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| 69 | return 0;
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| 70 | # endif
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| 71 | # endif
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| 72 | }
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| 73 |
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| 74 | # if LINUX_VERSION_CODE < KERNEL_VERSION(4, 2, 0)
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| 75 | # if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 13)
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| 76 | static void vbsf_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
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| 77 | # else
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| 78 | static void vbsf_put_link(struct dentry *dentry, struct nameidata *nd)
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| 79 | # endif
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| 80 | {
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| 81 | char *page = nd_get_link(nd);
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| 82 | if (!IS_ERR(page))
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| 83 | free_page((unsigned long)page);
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| 84 | }
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| 85 | # endif /* < 4.2.0 */
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| 86 |
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| 87 | # else /* >= 4.5.0 */
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| 88 |
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| 89 | static const char *vbsf_get_link(struct dentry *dentry, struct inode *inode, struct delayed_call *done)
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| 90 | {
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| 91 | struct vbsf_super_info *sf_g = VBSF_GET_SUPER_INFO(inode->i_sb);
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| 92 | struct sf_inode_info *sf_i = GET_INODE_INFO(inode);
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| 93 | char *path;
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| 94 | int rc;
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| 95 |
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| 96 | if (!dentry)
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| 97 | return ERR_PTR(-ECHILD);
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| 98 | path = kzalloc(PAGE_SIZE, GFP_KERNEL);
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| 99 | if (!path)
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| 100 | return ERR_PTR(-ENOMEM);
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| 101 | rc = VbglR0SfReadLink(&g_SfClient, &sf_g->map, sf_i->path, PATH_MAX, path);
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| 102 | if (RT_FAILURE(rc)) {
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| 103 | LogFunc(("VbglR0SfReadLink failed, rc=%Rrc\n", rc));
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| 104 | kfree(path);
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| 105 | return ERR_PTR(-EPROTO);
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| 106 | }
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| 107 | set_delayed_call(done, kfree_link, path);
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| 108 | return path;
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| 109 | }
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| 110 |
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| 111 | # endif /* >= 4.5.0 */
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| 112 |
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| 113 | struct inode_operations vbsf_lnk_iops = {
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| 114 | # if LINUX_VERSION_CODE < KERNEL_VERSION(4, 10, 0)
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| 115 | .readlink = generic_readlink,
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| 116 | # endif
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| 117 | # if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 5, 0)
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| 118 | .get_link = vbsf_get_link
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| 119 | # elif LINUX_VERSION_CODE >= KERNEL_VERSION(4, 2, 0)
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| 120 | .follow_link = vbsf_follow_link,
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| 121 | .put_link = free_page_put_link,
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| 122 | # else
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| 123 | .follow_link = vbsf_follow_link,
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| 124 | .put_link = vbsf_put_link
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| 125 | # endif
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| 126 | };
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| 127 |
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| 128 | #endif /* LINUX_VERSION_CODE >= 2.6.8 */
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