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autofs4: translate pids to the right namespace for the daemon
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The PID and the TGID of the process triggering the mount are sent to the
daemon.  Currently the global pid values are sent (ones valid in the
initial pid namespace) but this is wrong if the autofs daemon itself is
not running in the initial pid namespace.

So send the pid values that are valid in the namespace of the autofs
daemon.

The namespace to use is taken from the oz_pgrp pid pointer, which was
set at mount time to the mounting process' pid namespace.

If the pid translation fails (the triggering process is in an unrelated
pid namespace) then the automount fails with ENOENT.

Signed-off-by: Miklos Szeredi <[email protected]>
Acked-by: Serge Hallyn <[email protected]>
Cc: Eric Biederman <[email protected]>
Acked-by: Ian Kent <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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szmi authored and torvalds committed Jan 24, 2014
1 parent 6eaba35 commit fbff087
Showing 1 changed file with 14 additions and 2 deletions.
16 changes: 14 additions & 2 deletions fs/autofs4/waitq.c
Original file line number Diff line number Diff line change
Expand Up @@ -347,11 +347,23 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
struct qstr qstr;
char *name;
int status, ret, type;
pid_t pid;
pid_t tgid;

/* In catatonic mode, we don't wait for nobody */
if (sbi->catatonic)
return -ENOENT;

/*
* Try translating pids to the namespace of the daemon.
*
* Zero means failure: we are in an unrelated pid namespace.
*/
pid = task_pid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
tgid = task_tgid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
if (pid == 0 || tgid == 0)
return -ENOENT;

if (!dentry->d_inode) {
/*
* A wait for a negative dentry is invalid for certain
Expand Down Expand Up @@ -417,8 +429,8 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
wq->ino = autofs4_get_ino(sbi);
wq->uid = current_uid();
wq->gid = current_gid();
wq->pid = current->pid;
wq->tgid = current->tgid;
wq->pid = pid;
wq->tgid = tgid;
wq->status = -EINTR; /* Status return if interrupted */
wq->wait_ctr = 2;

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