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cdff2642 JJ |
1 | /* |
2 | * AppArmor security module | |
3 | * | |
4 | * This file contains AppArmor function for pathnames | |
5 | * | |
6 | * Copyright (C) 1998-2008 Novell/SUSE | |
7 | * Copyright 2009-2010 Canonical Ltd. | |
8 | * | |
9 | * This program is free software; you can redistribute it and/or | |
10 | * modify it under the terms of the GNU General Public License as | |
11 | * published by the Free Software Foundation, version 2 of the | |
12 | * License. | |
13 | */ | |
14 | ||
15 | #include <linux/magic.h> | |
cdff2642 JJ |
16 | #include <linux/mount.h> |
17 | #include <linux/namei.h> | |
18 | #include <linux/nsproxy.h> | |
19 | #include <linux/path.h> | |
20 | #include <linux/sched.h> | |
21 | #include <linux/slab.h> | |
22 | #include <linux/fs_struct.h> | |
23 | ||
24 | #include "include/apparmor.h" | |
25 | #include "include/path.h" | |
26 | #include "include/policy.h" | |
27 | ||
cdff2642 JJ |
28 | /* modified from dcache.c */ |
29 | static int prepend(char **buffer, int buflen, const char *str, int namelen) | |
30 | { | |
31 | buflen -= namelen; | |
32 | if (buflen < 0) | |
33 | return -ENAMETOOLONG; | |
34 | *buffer -= namelen; | |
35 | memcpy(*buffer, str, namelen); | |
36 | return 0; | |
37 | } | |
38 | ||
39 | #define CHROOT_NSCONNECT (PATH_CHROOT_REL | PATH_CHROOT_NSCONNECT) | |
40 | ||
a3c6147c JJ |
41 | /* If the path is not connected to the expected root, |
42 | * check if it is a sysctl and handle specially else remove any | |
43 | * leading / that __d_path may have returned. | |
44 | * Unless | |
45 | * specifically directed to connect the path, | |
46 | * OR | |
47 | * if in a chroot and doing chroot relative paths and the path | |
48 | * resolves to the namespace root (would be connected outside | |
49 | * of chroot) and specifically directed to connect paths to | |
50 | * namespace root. | |
51 | */ | |
52 | static int disconnect(struct path *path, char *buf, char **name, int flags, | |
53 | const char *disconnected) | |
54 | { | |
55 | int error = 0; | |
56 | ||
57 | if (!(flags & PATH_CONNECT_PATH) && | |
58 | !(((flags & CHROOT_NSCONNECT) == CHROOT_NSCONNECT) && | |
59 | our_mnt(path->mnt))) { | |
60 | /* disconnected path, don't return pathname starting | |
61 | * with '/' | |
62 | */ | |
63 | error = -EACCES; | |
64 | if (**name == '/') | |
65 | *name = *name + 1; | |
66 | } else { | |
67 | if (**name != '/') | |
68 | /* CONNECT_PATH with missing root */ | |
69 | error = prepend(name, *name - buf, "/", 1); | |
70 | if (!error && disconnected) | |
71 | error = prepend(name, *name - buf, disconnected, | |
72 | strlen(disconnected)); | |
73 | } | |
74 | ||
75 | return error; | |
76 | } | |
77 | ||
cdff2642 JJ |
78 | /** |
79 | * d_namespace_path - lookup a name associated with a given path | |
80 | * @path: path to lookup (NOT NULL) | |
81 | * @buf: buffer to store path to (NOT NULL) | |
cdff2642 JJ |
82 | * @name: Returns - pointer for start of path name with in @buf (NOT NULL) |
83 | * @flags: flags controlling path lookup | |
a3c6147c | 84 | * @disconnected: string to prefix to disconnected paths |
cdff2642 JJ |
85 | * |
86 | * Handle path name lookup. | |
87 | * | |
88 | * Returns: %0 else error code if path lookup fails | |
89 | * When no error the path name is returned in @name which points to | |
90 | * to a position in @buf | |
91 | */ | |
a3c6147c JJ |
92 | static int d_namespace_path(struct path *path, char *buf, char **name, |
93 | int flags, const char *disconnected) | |
cdff2642 | 94 | { |
cdff2642 | 95 | char *res; |
02125a82 AV |
96 | int error = 0; |
97 | int connected = 1; | |
a3c6147c JJ |
98 | int isdir = (flags & PATH_IS_DIR) ? 1 : 0; |
99 | int buflen = aa_g_path_max - isdir; | |
cdff2642 | 100 | |
02125a82 AV |
101 | if (path->mnt->mnt_flags & MNT_INTERNAL) { |
102 | /* it's not mounted anywhere */ | |
103 | res = dentry_path(path->dentry, buf, buflen); | |
104 | *name = res; | |
105 | if (IS_ERR(res)) { | |
106 | *name = buf; | |
107 | return PTR_ERR(res); | |
108 | } | |
109 | if (path->dentry->d_sb->s_magic == PROC_SUPER_MAGIC && | |
110 | strncmp(*name, "/sys/", 5) == 0) { | |
111 | /* TODO: convert over to using a per namespace | |
112 | * control instead of hard coded /proc | |
113 | */ | |
a3c6147c JJ |
114 | error = prepend(name, *name - buf, "/proc", 5); |
115 | goto out; | |
116 | } else | |
117 | error = disconnect(path, buf, name, flags, | |
118 | disconnected); | |
119 | goto out; | |
02125a82 AV |
120 | } |
121 | ||
122 | /* resolve paths relative to chroot?*/ | |
cdff2642 | 123 | if (flags & PATH_CHROOT_REL) { |
02125a82 | 124 | struct path root; |
44672e4f | 125 | get_fs_root(current->fs, &root); |
02125a82 | 126 | res = __d_path(path, &root, buf, buflen); |
02125a82 | 127 | path_put(&root); |
3372b68a | 128 | } else { |
28042fab | 129 | res = d_absolute_path(path, buf, buflen); |
3372b68a JJ |
130 | if (!our_mnt(path->mnt)) |
131 | connected = 0; | |
132 | } | |
cdff2642 | 133 | |
cdff2642 JJ |
134 | /* handle error conditions - and still allow a partial path to |
135 | * be returned. | |
136 | */ | |
3372b68a | 137 | if (!res || IS_ERR(res)) { |
a3c6147c JJ |
138 | if (PTR_ERR(res) == -ENAMETOOLONG) { |
139 | error = -ENAMETOOLONG; | |
140 | *name = buf; | |
141 | goto out; | |
142 | } | |
3372b68a | 143 | connected = 0; |
fbba8d89 JJ |
144 | res = dentry_path_raw(path->dentry, buf, buflen); |
145 | if (IS_ERR(res)) { | |
146 | error = PTR_ERR(res); | |
147 | *name = buf; | |
148 | goto out; | |
149 | }; | |
150 | } else if (!our_mnt(path->mnt)) | |
02125a82 | 151 | connected = 0; |
cdff2642 | 152 | |
fbba8d89 JJ |
153 | *name = res; |
154 | ||
e819ff51 JJ |
155 | /* Handle two cases: |
156 | * 1. A deleted dentry && profile is not allowing mediation of deleted | |
157 | * 2. On some filesystems, newly allocated dentries appear to the | |
158 | * security_path hooks as a deleted dentry except without an inode | |
159 | * allocated. | |
160 | */ | |
729b8a3d | 161 | if (d_unlinked(path->dentry) && d_is_positive(path->dentry) && |
e819ff51 | 162 | !(flags & PATH_MEDIATE_DELETED)) { |
cdff2642 JJ |
163 | error = -ENOENT; |
164 | goto out; | |
cdff2642 JJ |
165 | } |
166 | ||
a3c6147c JJ |
167 | if (!connected) |
168 | error = disconnect(path, buf, name, flags, disconnected); | |
cdff2642 JJ |
169 | |
170 | out: | |
a3c6147c JJ |
171 | /* |
172 | * Append "/" to the pathname. The root directory is a special | |
173 | * case; it already ends in slash. | |
174 | */ | |
175 | if (!error && isdir && ((*name)[1] != '\0' || (*name)[0] != '/')) | |
176 | strcpy(&buf[aa_g_path_max - 2], "/"); | |
57fa1e18 | 177 | |
cdff2642 JJ |
178 | return error; |
179 | } | |
180 | ||
181 | /** | |
a3c6147c | 182 | * aa_path_name - get the pathname to a buffer ensure dir / is appended |
cdff2642 JJ |
183 | * @path: path the file (NOT NULL) |
184 | * @flags: flags controlling path name generation | |
a3c6147c | 185 | * @buffer: buffer to put name in (NOT NULL) |
cdff2642 | 186 | * @name: Returns - the generated path name if !error (NOT NULL) |
57fa1e18 | 187 | * @info: Returns - information on why the path lookup failed (MAYBE NULL) |
a3c6147c | 188 | * @disconnected: string to prepend to disconnected paths |
cdff2642 JJ |
189 | * |
190 | * @name is a pointer to the beginning of the pathname (which usually differs | |
191 | * from the beginning of the buffer), or NULL. If there is an error @name | |
192 | * may contain a partial or invalid name that can be used for audit purposes, | |
193 | * but it can not be used for mediation. | |
194 | * | |
195 | * We need PATH_IS_DIR to indicate whether the file is a directory or not | |
196 | * because the file may not yet exist, and so we cannot check the inode's | |
197 | * file type. | |
198 | * | |
199 | * Returns: %0 else error code if could retrieve name | |
200 | */ | |
a3c6147c JJ |
201 | int aa_path_name(struct path *path, int flags, char *buffer, const char **name, |
202 | const char **info, const char *disconnected) | |
cdff2642 | 203 | { |
a3c6147c JJ |
204 | char *str = NULL; |
205 | int error = d_namespace_path(path, buffer, &str, flags, disconnected); | |
206 | ||
207 | ||
208 | if (info && error) { | |
209 | if (error == -ENOENT) | |
210 | *info = "Failed name lookup - deleted entry"; | |
211 | else if (error == -EACCES) | |
212 | *info = "Failed name lookup - disconnected path"; | |
213 | else if (error == -ENAMETOOLONG) | |
214 | *info = "Failed name lookup - name too long"; | |
215 | else | |
216 | *info = "Failed name lookup"; | |
cdff2642 | 217 | } |
94733bd5 | 218 | |
a3c6147c | 219 | *name = str; |
cdff2642 JJ |
220 | return error; |
221 | } |