1 files changed, 164 insertions, 21 deletions

diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
index b178ed733c36..b7a47196c8c3 100644
--- a/fs/proc/namespaces.c
+++ b/fs/proc/namespaces.c
@@ -11,6 +11,7 @@
 #include <net/net_namespace.h>
 #include <linux/ipc_namespace.h>
 #include <linux/pid_namespace.h>
+#include <linux/user_namespace.h>
 #include "internal.h"
 
 
@@ -24,12 +25,168 @@ static const struct proc_ns_operations *ns_entries[] = {
 #ifdef CONFIG_IPC_NS
         &ipcns_operations,
 #endif
+#ifdef CONFIG_PID_NS
+        &pidns_operations,
+#endif
+#ifdef CONFIG_USER_NS
+        &userns_operations,
+#endif
+        &mntns_operations,
 };
 
 static const struct file_operations ns_file_operations = {
         .llseek         = no_llseek,
 };
 
+static const struct inode_operations ns_inode_operations = {
+        .setattr        = proc_setattr,
+};
+
+static int ns_delete_dentry(const struct dentry *dentry)
+{
+        /* Don't cache namespace inodes when not in use */
+        return 1;
+}
+
+static char *ns_dname(struct dentry *dentry, char *buffer, int buflen)
+{
+        struct inode *inode = dentry->d_inode;
+        const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns_ops;
+
+        return dynamic_dname(dentry, buffer, buflen, "%s:[%lu]",
+                ns_ops->name, inode->i_ino);
+}
+
+const struct dentry_operations ns_dentry_operations =
+{
+        .d_delete       = ns_delete_dentry,
+        .d_dname        = ns_dname,
+};
+
+static struct dentry *proc_ns_get_dentry(struct super_block *sb,
+        struct task_struct *task, const struct proc_ns_operations *ns_ops)
+{
+        struct dentry *dentry, *result;
+        struct inode *inode;
+        struct proc_inode *ei;
+        struct qstr qname = { .name = "", };
+        void *ns;
+
+        ns = ns_ops->get(task);
+        if (!ns)
+                return ERR_PTR(-ENOENT);
+
+        dentry = d_alloc_pseudo(sb, &qname);
+        if (!dentry) {
+                ns_ops->put(ns);
+                return ERR_PTR(-ENOMEM);
+        }
+
+        inode = iget_locked(sb, ns_ops->inum(ns));
+        if (!inode) {
+                dput(dentry);
+                ns_ops->put(ns);
+                return ERR_PTR(-ENOMEM);
+        }
+
+        ei = PROC_I(inode);
+        if (inode->i_state & I_NEW) {
+                inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
+                inode->i_op = &ns_inode_operations;
+                inode->i_mode = S_IFREG | S_IRUGO;
+                inode->i_fop = &ns_file_operations;
+                ei->ns_ops = ns_ops;
+                ei->ns = ns;
+                unlock_new_inode(inode);
+        } else {
+                ns_ops->put(ns);
+        }
+
+        d_set_d_op(dentry, &ns_dentry_operations);
+        result = d_instantiate_unique(dentry, inode);
+        if (result) {
+                dput(dentry);
+                dentry = result;
+        }
+
+        return dentry;
+}
+
+static void *proc_ns_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+        struct inode *inode = dentry->d_inode;
+        struct super_block *sb = inode->i_sb;
+        struct proc_inode *ei = PROC_I(inode);
+        struct task_struct *task;
+        struct dentry *ns_dentry;
+        void *error = ERR_PTR(-EACCES);
+
+        task = get_proc_task(inode);
+        if (!task)
+                goto out;
+
+        if (!ptrace_may_access(task, PTRACE_MODE_READ))
+                goto out_put_task;
+
+        ns_dentry = proc_ns_get_dentry(sb, task, ei->ns_ops);
+        if (IS_ERR(ns_dentry)) {
+                error = ERR_CAST(ns_dentry);
+                goto out_put_task;
+        }
+
+        dput(nd->path.dentry);
+        nd->path.dentry = ns_dentry;
+        error = NULL;
+
+out_put_task:
+        put_task_struct(task);
+out:
+        return error;
+}
+
+static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int buflen)
+{
+        struct inode *inode = dentry->d_inode;
+        struct proc_inode *ei = PROC_I(inode);
+        const struct proc_ns_operations *ns_ops = ei->ns_ops;
+        struct task_struct *task;
+        void *ns;
+        char name[50];
+        int len = -EACCES;
+
+        task = get_proc_task(inode);
+        if (!task)
+                goto out;
+
+        if (!ptrace_may_access(task, PTRACE_MODE_READ))
+                goto out_put_task;
+
+        len = -ENOENT;
+        ns = ns_ops->get(task);
+        if (!ns)
+                goto out_put_task;
+
+        snprintf(name, sizeof(name), "%s:[%u]", ns_ops->name, ns_ops->inum(ns));
+        len = strlen(name);
+
+        if (len > buflen)
+                len = buflen;
+        if (copy_to_user(buffer, name, len))
+                len = -EFAULT;
+
+        ns_ops->put(ns);
+out_put_task:
+        put_task_struct(task);
+out:
+        return len;
+}
+
+static const struct inode_operations proc_ns_link_inode_operations = {
+        .readlink       = proc_ns_readlink,
+        .follow_link    = proc_ns_follow_link,
+        .setattr        = proc_setattr,
+};
+
 static struct dentry *proc_ns_instantiate(struct inode *dir,
         struct dentry *dentry, struct task_struct *task, const void *ptr)
 {
@@ -37,21 +194,15 @@ static struct dentry *proc_ns_instantiate(struct inode *dir,
         struct inode *inode;
         struct proc_inode *ei;
         struct dentry *error = ERR_PTR(-ENOENT);
-        void *ns;
 
         inode = proc_pid_make_inode(dir->i_sb, task);
         if (!inode)
                 goto out;
 
-        ns = ns_ops->get(task);
-        if (!ns)
-                goto out_iput;
-
         ei = PROC_I(inode);
-        inode->i_mode = S_IFREG|S_IRUSR;
-        inode->i_fop  = &ns_file_operations;
-        ei->ns_ops    = ns_ops;
-        ei->ns        = ns;
+        inode->i_mode = S_IFLNK|S_IRWXUGO;
+        inode->i_op = &proc_ns_link_inode_operations;
+        ei->ns_ops = ns_ops;
 
         d_set_d_op(dentry, &pid_dentry_operations);
         d_add(dentry, inode);
@@ -60,9 +211,6 @@ static struct dentry *proc_ns_instantiate(struct inode *dir,
                 error = NULL;
 out:
         return error;
-out_iput:
-        iput(inode);
-        goto out;
 }
 
 static int proc_ns_fill_cache(struct file *filp, void *dirent,
@@ -89,10 +237,6 @@ static int proc_ns_dir_readdir(struct file *filp, void *dirent,
         if (!task)
                 goto out_no_task;
 
-        ret = -EPERM;
-        if (!ptrace_may_access(task, PTRACE_MODE_READ))
-                goto out;
-
         ret = 0;
         i = filp->f_pos;
         switch (i) {
@@ -152,10 +296,6 @@ static struct dentry *proc_ns_dir_lookup(struct inode *dir,
         if (!task)
                 goto out_no_task;
 
-        error = ERR_PTR(-EPERM);
-        if (!ptrace_may_access(task, PTRACE_MODE_READ))
-                goto out;
-
         last = &ns_entries[ARRAY_SIZE(ns_entries)];
         for (entry = ns_entries; entry < last; entry++) {
                 if (strlen((*entry)->name) != len)
@@ -163,7 +303,6 @@ static struct dentry *proc_ns_dir_lookup(struct inode *dir,
                 if (!memcmp(dentry->d_name.name, (*entry)->name, len))
                         break;
         }
-        error = ERR_PTR(-ENOENT);
         if (entry == last)
                 goto out;
 
@@ -198,3 +337,7 @@ out_invalid:
         return ERR_PTR(-EINVAL);
 }
 
+bool proc_ns_inode(struct inode *inode)
+{
+        return inode->i_fop == &ns_file_operations;
+}