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![Eric W. Biederman](/assets/img/avatar_default.png)
Don't call iput with the inode half setup to be a namespace filedescriptor. Instead rearrange the code so that we don't initialize ei->ns_ops until after I ns_ops->get succeeds, preventing us from invoking ns_ops->put when ns_ops->get failed. Reported-by: Ingo Saitz <Ingo.Saitz@stud.uni-hannover.de> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
201 lines
4.1 KiB
C
201 lines
4.1 KiB
C
#include <linux/proc_fs.h>
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#include <linux/nsproxy.h>
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#include <linux/sched.h>
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#include <linux/ptrace.h>
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#include <linux/fs_struct.h>
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#include <linux/mount.h>
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#include <linux/path.h>
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#include <linux/namei.h>
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#include <linux/file.h>
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#include <linux/utsname.h>
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#include <net/net_namespace.h>
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#include <linux/mnt_namespace.h>
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#include <linux/ipc_namespace.h>
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#include <linux/pid_namespace.h>
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#include "internal.h"
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static const struct proc_ns_operations *ns_entries[] = {
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#ifdef CONFIG_NET_NS
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&netns_operations,
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#endif
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#ifdef CONFIG_UTS_NS
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&utsns_operations,
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#endif
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#ifdef CONFIG_IPC_NS
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&ipcns_operations,
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#endif
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};
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static const struct file_operations ns_file_operations = {
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.llseek = no_llseek,
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};
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static struct dentry *proc_ns_instantiate(struct inode *dir,
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struct dentry *dentry, struct task_struct *task, const void *ptr)
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{
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const struct proc_ns_operations *ns_ops = ptr;
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struct inode *inode;
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struct proc_inode *ei;
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struct dentry *error = ERR_PTR(-ENOENT);
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void *ns;
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inode = proc_pid_make_inode(dir->i_sb, task);
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if (!inode)
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goto out;
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ns = ns_ops->get(task);
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if (!ns)
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goto out_iput;
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ei = PROC_I(inode);
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inode->i_mode = S_IFREG|S_IRUSR;
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inode->i_fop = &ns_file_operations;
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ei->ns_ops = ns_ops;
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ei->ns = ns;
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dentry->d_op = &pid_dentry_operations;
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d_add(dentry, inode);
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/* Close the race of the process dying before we return the dentry */
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if (pid_revalidate(dentry, NULL))
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error = NULL;
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out:
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return error;
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out_iput:
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iput(inode);
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goto out;
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}
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static int proc_ns_fill_cache(struct file *filp, void *dirent,
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filldir_t filldir, struct task_struct *task,
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const struct proc_ns_operations *ops)
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{
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return proc_fill_cache(filp, dirent, filldir,
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ops->name, strlen(ops->name),
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proc_ns_instantiate, task, ops);
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}
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static int proc_ns_dir_readdir(struct file *filp, void *dirent,
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filldir_t filldir)
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{
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int i;
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struct dentry *dentry = filp->f_path.dentry;
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struct inode *inode = dentry->d_inode;
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struct task_struct *task = get_proc_task(inode);
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const struct proc_ns_operations **entry, **last;
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ino_t ino;
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int ret;
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ret = -ENOENT;
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if (!task)
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goto out_no_task;
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ret = -EPERM;
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if (!ptrace_may_access(task, PTRACE_MODE_READ))
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goto out;
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ret = 0;
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i = filp->f_pos;
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switch (i) {
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case 0:
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ino = inode->i_ino;
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if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
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goto out;
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i++;
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filp->f_pos++;
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/* fall through */
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case 1:
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ino = parent_ino(dentry);
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if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
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goto out;
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i++;
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filp->f_pos++;
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/* fall through */
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default:
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i -= 2;
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if (i >= ARRAY_SIZE(ns_entries)) {
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ret = 1;
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goto out;
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}
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entry = ns_entries + i;
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last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
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while (entry <= last) {
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if (proc_ns_fill_cache(filp, dirent, filldir,
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task, *entry) < 0)
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goto out;
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filp->f_pos++;
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entry++;
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}
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}
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ret = 1;
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out:
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put_task_struct(task);
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out_no_task:
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return ret;
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}
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const struct file_operations proc_ns_dir_operations = {
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.read = generic_read_dir,
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.readdir = proc_ns_dir_readdir,
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};
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static struct dentry *proc_ns_dir_lookup(struct inode *dir,
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struct dentry *dentry, struct nameidata *nd)
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{
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struct dentry *error;
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struct task_struct *task = get_proc_task(dir);
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const struct proc_ns_operations **entry, **last;
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unsigned int len = dentry->d_name.len;
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error = ERR_PTR(-ENOENT);
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if (!task)
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goto out_no_task;
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error = ERR_PTR(-EPERM);
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if (!ptrace_may_access(task, PTRACE_MODE_READ))
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goto out;
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last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
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for (entry = ns_entries; entry <= last; entry++) {
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if (strlen((*entry)->name) != len)
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continue;
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if (!memcmp(dentry->d_name.name, (*entry)->name, len))
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break;
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}
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error = ERR_PTR(-ENOENT);
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if (entry > last)
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goto out;
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error = proc_ns_instantiate(dir, dentry, task, *entry);
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out:
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put_task_struct(task);
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out_no_task:
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return error;
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}
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const struct inode_operations proc_ns_dir_inode_operations = {
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.lookup = proc_ns_dir_lookup,
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.getattr = pid_getattr,
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.setattr = proc_setattr,
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};
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struct file *proc_ns_fget(int fd)
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{
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struct file *file;
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file = fget(fd);
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if (!file)
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return ERR_PTR(-EBADF);
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if (file->f_op != &ns_file_operations)
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goto out_invalid;
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return file;
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out_invalid:
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fput(file);
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return ERR_PTR(-EINVAL);
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}
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