Merge branch 'upstream' of git://git.infradead.org/users/pcmoore/selinux into for...
[firefly-linux-kernel-4.4.55.git] / fs / proc / namespaces.c
1 #include <linux/proc_fs.h>
2 #include <linux/nsproxy.h>
3 #include <linux/ptrace.h>
4 #include <linux/namei.h>
5 #include <linux/file.h>
6 #include <linux/utsname.h>
7 #include <net/net_namespace.h>
8 #include <linux/ipc_namespace.h>
9 #include <linux/pid_namespace.h>
10 #include <linux/user_namespace.h>
11 #include "internal.h"
12
13
14 static const struct proc_ns_operations *ns_entries[] = {
15 #ifdef CONFIG_NET_NS
16         &netns_operations,
17 #endif
18 #ifdef CONFIG_UTS_NS
19         &utsns_operations,
20 #endif
21 #ifdef CONFIG_IPC_NS
22         &ipcns_operations,
23 #endif
24 #ifdef CONFIG_PID_NS
25         &pidns_operations,
26 #endif
27 #ifdef CONFIG_USER_NS
28         &userns_operations,
29 #endif
30         &mntns_operations,
31 };
32
33 static const char *proc_ns_follow_link(struct dentry *dentry, void **cookie)
34 {
35         struct inode *inode = d_inode(dentry);
36         const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns_ops;
37         struct task_struct *task;
38         struct path ns_path;
39         void *error = ERR_PTR(-EACCES);
40
41         task = get_proc_task(inode);
42         if (!task)
43                 return error;
44
45         if (ptrace_may_access(task, PTRACE_MODE_READ)) {
46                 error = ns_get_path(&ns_path, task, ns_ops);
47                 if (!error)
48                         nd_jump_link(&ns_path);
49         }
50         put_task_struct(task);
51         return error;
52 }
53
54 static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int buflen)
55 {
56         struct inode *inode = d_inode(dentry);
57         const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns_ops;
58         struct task_struct *task;
59         char name[50];
60         int res = -EACCES;
61
62         task = get_proc_task(inode);
63         if (!task)
64                 return res;
65
66         if (ptrace_may_access(task, PTRACE_MODE_READ)) {
67                 res = ns_get_name(name, sizeof(name), task, ns_ops);
68                 if (res >= 0)
69                         res = readlink_copy(buffer, buflen, name);
70         }
71         put_task_struct(task);
72         return res;
73 }
74
75 static const struct inode_operations proc_ns_link_inode_operations = {
76         .readlink       = proc_ns_readlink,
77         .follow_link    = proc_ns_follow_link,
78         .setattr        = proc_setattr,
79 };
80
81 static int proc_ns_instantiate(struct inode *dir,
82         struct dentry *dentry, struct task_struct *task, const void *ptr)
83 {
84         const struct proc_ns_operations *ns_ops = ptr;
85         struct inode *inode;
86         struct proc_inode *ei;
87
88         inode = proc_pid_make_inode(dir->i_sb, task);
89         if (!inode)
90                 goto out;
91
92         ei = PROC_I(inode);
93         inode->i_mode = S_IFLNK|S_IRWXUGO;
94         inode->i_op = &proc_ns_link_inode_operations;
95         ei->ns_ops = ns_ops;
96
97         d_set_d_op(dentry, &pid_dentry_operations);
98         d_add(dentry, inode);
99         /* Close the race of the process dying before we return the dentry */
100         if (pid_revalidate(dentry, 0))
101                 return 0;
102 out:
103         return -ENOENT;
104 }
105
106 static int proc_ns_dir_readdir(struct file *file, struct dir_context *ctx)
107 {
108         struct task_struct *task = get_proc_task(file_inode(file));
109         const struct proc_ns_operations **entry, **last;
110
111         if (!task)
112                 return -ENOENT;
113
114         if (!dir_emit_dots(file, ctx))
115                 goto out;
116         if (ctx->pos >= 2 + ARRAY_SIZE(ns_entries))
117                 goto out;
118         entry = ns_entries + (ctx->pos - 2);
119         last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
120         while (entry <= last) {
121                 const struct proc_ns_operations *ops = *entry;
122                 if (!proc_fill_cache(file, ctx, ops->name, strlen(ops->name),
123                                      proc_ns_instantiate, task, ops))
124                         break;
125                 ctx->pos++;
126                 entry++;
127         }
128 out:
129         put_task_struct(task);
130         return 0;
131 }
132
133 const struct file_operations proc_ns_dir_operations = {
134         .read           = generic_read_dir,
135         .iterate        = proc_ns_dir_readdir,
136 };
137
138 static struct dentry *proc_ns_dir_lookup(struct inode *dir,
139                                 struct dentry *dentry, unsigned int flags)
140 {
141         int error;
142         struct task_struct *task = get_proc_task(dir);
143         const struct proc_ns_operations **entry, **last;
144         unsigned int len = dentry->d_name.len;
145
146         error = -ENOENT;
147
148         if (!task)
149                 goto out_no_task;
150
151         last = &ns_entries[ARRAY_SIZE(ns_entries)];
152         for (entry = ns_entries; entry < last; entry++) {
153                 if (strlen((*entry)->name) != len)
154                         continue;
155                 if (!memcmp(dentry->d_name.name, (*entry)->name, len))
156                         break;
157         }
158         if (entry == last)
159                 goto out;
160
161         error = proc_ns_instantiate(dir, dentry, task, *entry);
162 out:
163         put_task_struct(task);
164 out_no_task:
165         return ERR_PTR(error);
166 }
167
168 const struct inode_operations proc_ns_dir_inode_operations = {
169         .lookup         = proc_ns_dir_lookup,
170         .getattr        = pid_getattr,
171         .setattr        = proc_setattr,
172 };