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Subject[PATCH] proc: Proper pidns handling for /proc/self
Date

Currently if you access a /proc that is not mounted with your
processes current pid namespace /proc/self will point at a completely
different process. Ouch!.
This patch fixes /proc/self to point to the current process if
it is available in the particular mount of /proc or to return
-ENOENT if the current process is not visible.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
fs/proc/base.c | 12 ++++++++++--
1 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 7e8eca4..34a1821 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2049,15 +2049,23 @@ static const struct file_operations proc_coredump_filter_operations = {
static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
int buflen)
{
+ struct pid_namespace *ns = dentry->d_sb->s_fs_info;
+ pid_t tgid = task_tgid_nr_ns(current, ns);
char tmp[PROC_NUMBUF];
- sprintf(tmp, "%d", task_tgid_vnr(current));
+ if (!tgid)
+ return -ENOENT;
+ sprintf(tmp, "%d", tgid);
return vfs_readlink(dentry,buffer,buflen,tmp);
}

static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd)
{
+ struct pid_namespace *ns = dentry->d_sb->s_fs_info;
+ pid_t tgid = task_tgid_nr_ns(current, ns);
char tmp[PROC_NUMBUF];
- sprintf(tmp, "%d", task_tgid_vnr(current));
+ if (!tgid)
+ return ERR_PTR(-ENOENT);
+ sprintf(tmp, "%d", task_tgid_nr_ns(current, ns));
return ERR_PTR(vfs_follow_link(nd,tmp));
}

--
1.5.3.rc6.17.g1911
-
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