Cache the mounters credentials and make access to the net directories
contingent of the permissions of the mounter of proc.
Show /proc/self/net only if mounter has CAP_NET_ADMIN and if proc is
mounted with subset=pid option.
Signed-off-by: Alexey Gladkov <[email protected]>
---
fs/proc/proc_net.c | 8 ++++++++
fs/proc/root.c | 7 +++++++
include/linux/proc_fs.h | 1 +
3 files changed, 16 insertions(+)
diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c
index 18601042af99..a198f74cdb3b 100644
--- a/fs/proc/proc_net.c
+++ b/fs/proc/proc_net.c
@@ -26,6 +26,7 @@
#include <linux/uidgid.h>
#include <net/net_namespace.h>
#include <linux/seq_file.h>
+#include <linux/security.h>
#include "internal.h"
@@ -259,6 +260,7 @@ static struct net *get_proc_task_net(struct inode *dir)
struct task_struct *task;
struct nsproxy *ns;
struct net *net = NULL;
+ struct proc_fs_info *fs_info = proc_sb_info(dir->i_sb);
rcu_read_lock();
task = pid_task(proc_pid(dir), PIDTYPE_PID);
@@ -271,6 +273,12 @@ static struct net *get_proc_task_net(struct inode *dir)
}
rcu_read_unlock();
+ if (net && (fs_info->pidonly == PROC_PIDONLY_ON) &&
+ security_capable(fs_info->mounter_cred, net->user_ns, CAP_NET_ADMIN, CAP_OPT_NONE) < 0) {
+ put_net(net);
+ net = NULL;
+ }
+
return net;
}
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 051ffe5e67ce..0ab90e24d9ae 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -185,6 +185,8 @@ static int proc_fill_super(struct super_block *s, struct fs_context *fc)
s->s_fs_info = fs_info;
fs_info->pid_ns = get_pid_ns(ctx->pid_ns);
+ fs_info->mounter_cred = get_cred(fc->cred);
+
proc_apply_options(s, fc, current_user_ns());
/*
@@ -220,9 +222,13 @@ static int proc_fill_super(struct super_block *s, struct fs_context *fc)
static int proc_reconfigure(struct fs_context *fc)
{
struct super_block *sb = fc->root->d_sb;
+ struct proc_fs_info *fs_info = proc_sb_info(sb);
sync_filesystem(sb);
+ put_cred(fs_info->mounter_cred);
+ fs_info->mounter_cred = get_cred(fc->cred);
+
proc_apply_options(sb, fc, current_user_ns());
return 0;
}
@@ -277,6 +283,7 @@ static void proc_kill_sb(struct super_block *sb)
kill_anon_super(sb);
put_pid_ns(fs_info->pid_ns);
+ put_cred(fs_info->mounter_cred);
kfree(fs_info);
}
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index 000cc0533c33..ffa871941bd0 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -64,6 +64,7 @@ struct proc_fs_info {
kgid_t pid_gid;
enum proc_hidepid hide_pid;
enum proc_pidonly pidonly;
+ const struct cred *mounter_cred;
};
static inline struct proc_fs_info *proc_sb_info(struct super_block *sb)
--
2.29.2