lkml.org 
[lkml]   [2018]   [Nov]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] Security: Handle hidepid option correctly
Date
From: Cheng Yang <chengyang@xiaomi.com>

The proc_parse_options() call from proc_mount() runs only once at boot
time. So on any later mount attempt, any mount options are ignored
because ->s_root is already initialized.
As a consequence, "mount -o <options>" will ignore the options. The
only way to change mount options is "mount -o remount,<options>".
To fix this, parse the mount options unconditionally.

Signed-off-by: Cheng Yang <chengyang@xiaomi.com>
---
fs/proc/inode.c | 4 ----
fs/proc/root.c | 3 +++
2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 5792f9e..ec509d1 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -493,13 +493,9 @@ struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)

int proc_fill_super(struct super_block *s, void *data, int silent)
{
- struct pid_namespace *ns = get_pid_ns(s->s_fs_info);
struct inode *root_inode;
int ret;

- if (!proc_parse_options(data, ns))
- return -EINVAL;
-
/* User space would break if executables or devices appear on proc */
s->s_iflags |= SB_I_USERNS_VISIBLE | SB_I_NOEXEC | SB_I_NODEV;
s->s_flags |= SB_NODIRATIME | SB_NOSUID | SB_NOEXEC;
diff --git a/fs/proc/root.c b/fs/proc/root.c
index f4b1a9d..f5f3bf3 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -98,6 +98,9 @@ static struct dentry *proc_mount(struct file_system_type *fs_type,
ns = task_active_pid_ns(current);
}

+ if (!proc_parse_options(data, ns))
+ return ERR_PTR(-EINVAL);
+
return mount_ns(fs_type, flags, data, ns, ns->user_ns, proc_fill_super);
}

--
1.9.1
\
 
 \ /
  Last update: 2018-11-29 12:09    [W:0.156 / U:0.864 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site