From c450f371d48557e3e0fa510a4af27b92f0d8c4cc Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Tue, 14 Aug 2012 21:25:13 -0700 Subject: userns: For /proc/self/{uid,gid}_map derive the lower userns from the struct file To keep things sane in the context of file descriptor passing derive the user namespace that uids are mapped into from the opener of the file instead of from current. When writing to the maps file the lower user namespace must always be the parent user namespace, or setting the mapping simply does not make sense. Enforce that the opener of the file was in the parent user namespace or the user namespace whose mapping is being set. Acked-by: Serge E. Hallyn Signed-off-by: "Eric W. Biederman" --- kernel/user_namespace.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index ce92f7e6290a..89f6eaed067a 100644 --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -391,7 +391,7 @@ static int uid_m_show(struct seq_file *seq, void *v) struct user_namespace *lower_ns; uid_t lower; - lower_ns = current_user_ns(); + lower_ns = seq_user_ns(seq); if ((lower_ns == ns) && lower_ns->parent) lower_ns = lower_ns->parent; @@ -412,7 +412,7 @@ static int gid_m_show(struct seq_file *seq, void *v) struct user_namespace *lower_ns; gid_t lower; - lower_ns = current_user_ns(); + lower_ns = seq_user_ns(seq); if ((lower_ns == ns) && lower_ns->parent) lower_ns = lower_ns->parent; @@ -688,10 +688,14 @@ ssize_t proc_uid_map_write(struct file *file, const char __user *buf, size_t siz { struct seq_file *seq = file->private_data; struct user_namespace *ns = seq->private; + struct user_namespace *seq_ns = seq_user_ns(seq); if (!ns->parent) return -EPERM; + if ((seq_ns != ns) && (seq_ns != ns->parent)) + return -EPERM; + return map_write(file, buf, size, ppos, CAP_SETUID, &ns->uid_map, &ns->parent->uid_map); } @@ -700,10 +704,14 @@ ssize_t proc_gid_map_write(struct file *file, const char __user *buf, size_t siz { struct seq_file *seq = file->private_data; struct user_namespace *ns = seq->private; + struct user_namespace *seq_ns = seq_user_ns(seq); if (!ns->parent) return -EPERM; + if ((seq_ns != ns) && (seq_ns != ns->parent)) + return -EPERM; + return map_write(file, buf, size, ppos, CAP_SETGID, &ns->gid_map, &ns->parent->gid_map); } -- cgit v1.2.1