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Commit | Line | Data |
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90996ada GKH |
1 | From 23adbe12ef7d3d4195e80800ab36b37bee28cd03 Mon Sep 17 00:00:00 2001 |
2 | From: Andy Lutomirski <luto@amacapital.net> | |
3 | Date: Tue, 10 Jun 2014 12:45:42 -0700 | |
4 | Subject: fs,userns: Change inode_capable to capable_wrt_inode_uidgid | |
5 | ||
6 | From: Andy Lutomirski <luto@amacapital.net> | |
7 | ||
8 | commit 23adbe12ef7d3d4195e80800ab36b37bee28cd03 upstream. | |
9 | ||
10 | The kernel has no concept of capabilities with respect to inodes; inodes | |
11 | exist independently of namespaces. For example, inode_capable(inode, | |
12 | CAP_LINUX_IMMUTABLE) would be nonsense. | |
13 | ||
14 | This patch changes inode_capable to check for uid and gid mappings and | |
15 | renames it to capable_wrt_inode_uidgid, which should make it more | |
16 | obvious what it does. | |
17 | ||
18 | Fixes CVE-2014-4014. | |
19 | ||
20 | Cc: Theodore Ts'o <tytso@mit.edu> | |
21 | Cc: Serge Hallyn <serge.hallyn@ubuntu.com> | |
22 | Cc: "Eric W. Biederman" <ebiederm@xmission.com> | |
23 | Cc: Dave Chinner <david@fromorbit.com> | |
24 | Signed-off-by: Andy Lutomirski <luto@amacapital.net> | |
25 | Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> | |
26 | Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> | |
27 | ||
28 | --- | |
29 | fs/attr.c | 8 ++++---- | |
30 | fs/inode.c | 10 +++++++--- | |
31 | fs/namei.c | 11 ++++++----- | |
32 | fs/xfs/xfs_ioctl.c | 2 +- | |
33 | include/linux/capability.h | 2 +- | |
34 | kernel/capability.c | 20 ++++++++------------ | |
35 | 6 files changed, 27 insertions(+), 26 deletions(-) | |
36 | ||
37 | --- a/fs/attr.c | |
38 | +++ b/fs/attr.c | |
39 | @@ -50,14 +50,14 @@ int inode_change_ok(const struct inode * | |
40 | if ((ia_valid & ATTR_UID) && | |
41 | (!uid_eq(current_fsuid(), inode->i_uid) || | |
42 | !uid_eq(attr->ia_uid, inode->i_uid)) && | |
43 | - !inode_capable(inode, CAP_CHOWN)) | |
44 | + !capable_wrt_inode_uidgid(inode, CAP_CHOWN)) | |
45 | return -EPERM; | |
46 | ||
47 | /* Make sure caller can chgrp. */ | |
48 | if ((ia_valid & ATTR_GID) && | |
49 | (!uid_eq(current_fsuid(), inode->i_uid) || | |
50 | (!in_group_p(attr->ia_gid) && !gid_eq(attr->ia_gid, inode->i_gid))) && | |
51 | - !inode_capable(inode, CAP_CHOWN)) | |
52 | + !capable_wrt_inode_uidgid(inode, CAP_CHOWN)) | |
53 | return -EPERM; | |
54 | ||
55 | /* Make sure a caller can chmod. */ | |
56 | @@ -67,7 +67,7 @@ int inode_change_ok(const struct inode * | |
57 | /* Also check the setgid bit! */ | |
58 | if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid : | |
59 | inode->i_gid) && | |
60 | - !inode_capable(inode, CAP_FSETID)) | |
61 | + !capable_wrt_inode_uidgid(inode, CAP_FSETID)) | |
62 | attr->ia_mode &= ~S_ISGID; | |
63 | } | |
64 | ||
65 | @@ -160,7 +160,7 @@ void setattr_copy(struct inode *inode, c | |
66 | umode_t mode = attr->ia_mode; | |
67 | ||
68 | if (!in_group_p(inode->i_gid) && | |
69 | - !inode_capable(inode, CAP_FSETID)) | |
70 | + !capable_wrt_inode_uidgid(inode, CAP_FSETID)) | |
71 | mode &= ~S_ISGID; | |
72 | inode->i_mode = mode; | |
73 | } | |
74 | --- a/fs/inode.c | |
75 | +++ b/fs/inode.c | |
76 | @@ -1840,14 +1840,18 @@ EXPORT_SYMBOL(inode_init_owner); | |
77 | * inode_owner_or_capable - check current task permissions to inode | |
78 | * @inode: inode being checked | |
79 | * | |
80 | - * Return true if current either has CAP_FOWNER to the inode, or | |
81 | - * owns the file. | |
82 | + * Return true if current either has CAP_FOWNER in a namespace with the | |
83 | + * inode owner uid mapped, or owns the file. | |
84 | */ | |
85 | bool inode_owner_or_capable(const struct inode *inode) | |
86 | { | |
87 | + struct user_namespace *ns; | |
88 | + | |
89 | if (uid_eq(current_fsuid(), inode->i_uid)) | |
90 | return true; | |
91 | - if (inode_capable(inode, CAP_FOWNER)) | |
92 | + | |
93 | + ns = current_user_ns(); | |
94 | + if (ns_capable(ns, CAP_FOWNER) && kuid_has_mapping(ns, inode->i_uid)) | |
95 | return true; | |
96 | return false; | |
97 | } | |
98 | --- a/fs/namei.c | |
99 | +++ b/fs/namei.c | |
100 | @@ -332,10 +332,11 @@ int generic_permission(struct inode *ino | |
101 | ||
102 | if (S_ISDIR(inode->i_mode)) { | |
103 | /* DACs are overridable for directories */ | |
104 | - if (inode_capable(inode, CAP_DAC_OVERRIDE)) | |
105 | + if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) | |
106 | return 0; | |
107 | if (!(mask & MAY_WRITE)) | |
108 | - if (inode_capable(inode, CAP_DAC_READ_SEARCH)) | |
109 | + if (capable_wrt_inode_uidgid(inode, | |
110 | + CAP_DAC_READ_SEARCH)) | |
111 | return 0; | |
112 | return -EACCES; | |
113 | } | |
114 | @@ -345,7 +346,7 @@ int generic_permission(struct inode *ino | |
115 | * at least one exec bit set. | |
116 | */ | |
117 | if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) | |
118 | - if (inode_capable(inode, CAP_DAC_OVERRIDE)) | |
119 | + if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) | |
120 | return 0; | |
121 | ||
122 | /* | |
123 | @@ -353,7 +354,7 @@ int generic_permission(struct inode *ino | |
124 | */ | |
125 | mask &= MAY_READ | MAY_WRITE | MAY_EXEC; | |
126 | if (mask == MAY_READ) | |
127 | - if (inode_capable(inode, CAP_DAC_READ_SEARCH)) | |
128 | + if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) | |
129 | return 0; | |
130 | ||
131 | return -EACCES; | |
132 | @@ -2370,7 +2371,7 @@ static inline int check_sticky(struct in | |
133 | return 0; | |
134 | if (uid_eq(dir->i_uid, fsuid)) | |
135 | return 0; | |
136 | - return !inode_capable(inode, CAP_FOWNER); | |
137 | + return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); | |
138 | } | |
139 | ||
140 | /* | |
141 | --- a/fs/xfs/xfs_ioctl.c | |
142 | +++ b/fs/xfs/xfs_ioctl.c | |
143 | @@ -1241,7 +1241,7 @@ xfs_ioctl_setattr( | |
144 | * cleared upon successful return from chown() | |
145 | */ | |
146 | if ((ip->i_d.di_mode & (S_ISUID|S_ISGID)) && | |
147 | - !inode_capable(VFS_I(ip), CAP_FSETID)) | |
148 | + !capable_wrt_inode_uidgid(VFS_I(ip), CAP_FSETID)) | |
149 | ip->i_d.di_mode &= ~(S_ISUID|S_ISGID); | |
150 | ||
151 | /* | |
152 | --- a/include/linux/capability.h | |
153 | +++ b/include/linux/capability.h | |
154 | @@ -210,7 +210,7 @@ extern bool has_ns_capability_noaudit(st | |
155 | struct user_namespace *ns, int cap); | |
156 | extern bool capable(int cap); | |
157 | extern bool ns_capable(struct user_namespace *ns, int cap); | |
158 | -extern bool inode_capable(const struct inode *inode, int cap); | |
159 | +extern bool capable_wrt_inode_uidgid(const struct inode *inode, int cap); | |
160 | extern bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap); | |
161 | ||
162 | /* audit system wants to get cap info from files as well */ | |
163 | --- a/kernel/capability.c | |
164 | +++ b/kernel/capability.c | |
165 | @@ -433,23 +433,19 @@ bool capable(int cap) | |
166 | EXPORT_SYMBOL(capable); | |
167 | ||
168 | /** | |
169 | - * inode_capable - Check superior capability over inode | |
170 | + * capable_wrt_inode_uidgid - Check nsown_capable and uid and gid mapped | |
171 | * @inode: The inode in question | |
172 | * @cap: The capability in question | |
173 | * | |
174 | - * Return true if the current task has the given superior capability | |
175 | - * targeted at it's own user namespace and that the given inode is owned | |
176 | - * by the current user namespace or a child namespace. | |
177 | - * | |
178 | - * Currently we check to see if an inode is owned by the current | |
179 | - * user namespace by seeing if the inode's owner maps into the | |
180 | - * current user namespace. | |
181 | - * | |
182 | + * Return true if the current task has the given capability targeted at | |
183 | + * its own user namespace and that the given inode's uid and gid are | |
184 | + * mapped into the current user namespace. | |
185 | */ | |
186 | -bool inode_capable(const struct inode *inode, int cap) | |
187 | +bool capable_wrt_inode_uidgid(const struct inode *inode, int cap) | |
188 | { | |
189 | struct user_namespace *ns = current_user_ns(); | |
190 | ||
191 | - return ns_capable(ns, cap) && kuid_has_mapping(ns, inode->i_uid); | |
192 | + return ns_capable(ns, cap) && kuid_has_mapping(ns, inode->i_uid) && | |
193 | + kgid_has_mapping(ns, inode->i_gid); | |
194 | } | |
195 | -EXPORT_SYMBOL(inode_capable); | |
196 | +EXPORT_SYMBOL(capable_wrt_inode_uidgid); |