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Message-ID: <5547156.nUWVlrP4MO@pegasus>
Date: Sat, 25 May 2013 07:32:33 +0000
From: Stephen Mell <sub.atomic.fusion@...il.com>
To: linux-kernel@...r.kernel.org
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH] proc: move proc mount options out of pid_namespace
From: Stephen Mell <sub.atomic.fusion@...il.com>
hide_pid and pid_gid are proc mount options whose values are stored in the pid_namespace struct. As a result, if one mounts proc again for the same PID namespace with different mount options, all mounts for that PID namespace will be affected. This seems undesirable. This patch creates a proc_sb_info struct that points to the applicable PID namespace, and it moves hide_pid, pid_gid, and proc_self from pid_namespace to proc_sb_info. This patch removes a redundant null pointer check prior to calling dput which it would otherwise have to readd.
Signed-off-by: Stephen Mell <sub.atomic.fusion@...il.com>
---
fs/proc/base.c | 38 +++++++++++++++++----------
fs/proc/inode.c | 10 ++++----
fs/proc/internal.h | 8 ++++++
fs/proc/root.c | 60 +++++++++++++++++++++++++------------------
fs/proc/self.c | 10 +++++---
include/linux/pid_namespace.h | 3 ---
6 files changed, 78 insertions(+), 51 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index dd51e50..853eb68 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -584,13 +584,13 @@ int proc_setattr(struct dentry *dentry, struct iattr *attr)
* May current process learn task's sched/cmdline info (for hide_pid_min=1)
* or euid/egid (for hide_pid_min=2)?
*/
-static bool has_pid_permissions(struct pid_namespace *pid,
+static bool has_pid_permissions(struct proc_sb_info *fsi,
struct task_struct *task,
int hide_pid_min)
{
- if (pid->hide_pid < hide_pid_min)
+ if (fsi->hide_pid < hide_pid_min)
return true;
- if (in_group_p(pid->pid_gid))
+ if (in_group_p(fsi->pid_gid))
return true;
return ptrace_may_access(task, PTRACE_MODE_READ);
}
@@ -598,18 +598,18 @@ static bool has_pid_permissions(struct pid_namespace *pid,
static int proc_pid_permission(struct inode *inode, int mask)
{
- struct pid_namespace *pid = inode->i_sb->s_fs_info;
+ struct proc_sb_info *fsi = inode->i_sb->s_fs_info;
struct task_struct *task;
bool has_perms;
task = get_proc_task(inode);
if (!task)
return -ESRCH;
- has_perms = has_pid_permissions(pid, task, 1);
+ has_perms = has_pid_permissions(fsi, task, 1);
put_task_struct(task);
if (!has_perms) {
- if (pid->hide_pid == 2) {
+ if (fsi->hide_pid == 2) {
/*
* Let's make getdents(), stat(), and open()
* consistent with each other. If a process
@@ -670,12 +670,14 @@ static const struct file_operations proc_info_file_operations = {
static int proc_single_show(struct seq_file *m, void *v)
{
struct inode *inode = m->private;
+ struct proc_sb_info *fsi;
struct pid_namespace *ns;
struct pid *pid;
struct task_struct *task;
int ret;
- ns = inode->i_sb->s_fs_info;
+ fsi = inode->i_sb->s_fs_info;
+ ns = fsi->ns;
pid = proc_pid(inode);
task = get_pid_task(pid, PIDTYPE_PID);
if (!task)
@@ -1574,7 +1576,7 @@ int pid_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
struct inode *inode = dentry->d_inode;
struct task_struct *task;
const struct cred *cred;
- struct pid_namespace *pid = dentry->d_sb->s_fs_info;
+ struct proc_sb_info *fsi = dentry->d_sb->s_fs_info;
generic_fillattr(inode, stat);
@@ -1583,7 +1585,7 @@ int pid_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
stat->gid = GLOBAL_ROOT_GID;
task = pid_task(proc_pid(inode), PIDTYPE_PID);
if (task) {
- if (!has_pid_permissions(pid, task, 2)) {
+ if (!has_pid_permissions(fsi, task, 2)) {
rcu_read_unlock();
/*
* This doesn't prevent learning whether PID exists,
@@ -2869,13 +2871,15 @@ struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, unsign
struct dentry *result = NULL;
struct task_struct *task;
unsigned tgid;
+ struct proc_sb_info *fsi;
struct pid_namespace *ns;
tgid = name_to_int(dentry);
if (tgid == ~0U)
goto out;
- ns = dentry->d_sb->s_fs_info;
+ fsi = dentry->d_sb->s_fs_info;
+ ns = fsi->ns;
rcu_read_lock();
task = find_task_by_pid_ns(tgid, ns);
if (task)
@@ -2954,6 +2958,7 @@ static int fake_filldir(void *buf, const char *name, int namelen,
int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
struct tgid_iter iter;
+ struct proc_sb_info *fsi;
struct pid_namespace *ns;
filldir_t __filldir;
loff_t pos = filp->f_pos;
@@ -2970,11 +2975,12 @@ int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
iter.tgid = pos - TGID_OFFSET;
}
iter.task = NULL;
- ns = filp->f_dentry->d_sb->s_fs_info;
+ fsi = filp->f_dentry->d_sb->s_fs_info;
+ ns = fsi->ns;
for (iter = next_tgid(ns, iter);
iter.task;
iter.tgid += 1, iter = next_tgid(ns, iter)) {
- if (has_pid_permissions(ns, iter.task, 2))
+ if (has_pid_permissions(fsi, iter.task, 2))
__filldir = filldir;
else
__filldir = fake_filldir;
@@ -3132,6 +3138,7 @@ static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry
struct task_struct *task;
struct task_struct *leader = get_proc_task(dir);
unsigned tid;
+ struct proc_sb_info *fsi;
struct pid_namespace *ns;
if (!leader)
@@ -3141,7 +3148,8 @@ static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry
if (tid == ~0U)
goto out;
- ns = dentry->d_sb->s_fs_info;
+ fsi = dentry->d_sb->s_fs_info;
+ ns = fsi->ns;
rcu_read_lock();
task = find_task_by_pid_ns(tid, ns);
if (task)
@@ -3249,6 +3257,7 @@ static int proc_task_readdir(struct file * filp, void * dirent, filldir_t filldi
int retval = -ENOENT;
ino_t ino;
int tid;
+ struct proc_sb_info *fsi;
struct pid_namespace *ns;
task = get_proc_task(inode);
@@ -3283,7 +3292,8 @@ static int proc_task_readdir(struct file * filp, void * dirent, filldir_t filldi
/* f_version caches the tgid value that the last readdir call couldn't
* return. lseek aka telldir automagically resets f_version to 0.
*/
- ns = filp->f_dentry->d_sb->s_fs_info;
+ fsi = filp->f_dentry->d_sb->s_fs_info;
+ ns = fsi->ns;
tid = (int)filp->f_version;
filp->f_version = 0;
for (task = first_tid(leader, tid, filp->f_pos - 2, ns);
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 073aea6..148737d 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -110,12 +110,12 @@ void __init proc_init_inodecache(void)
static int proc_show_options(struct seq_file *seq, struct dentry *root)
{
struct super_block *sb = root->d_sb;
- struct pid_namespace *pid = sb->s_fs_info;
+ struct proc_sb_info *fsi = sb->s_fs_info;
- if (!gid_eq(pid->pid_gid, GLOBAL_ROOT_GID))
- seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, pid->pid_gid));
- if (pid->hide_pid != 0)
- seq_printf(seq, ",hidepid=%u", pid->hide_pid);
+ if (!gid_eq(fsi->pid_gid, GLOBAL_ROOT_GID))
+ seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, fsi->pid_gid));
+ if (fsi->hide_pid != 0)
+ seq_printf(seq, ",hidepid=%u", fsi->hide_pid);
return 0;
}
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index d600fb0..ff970e4 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -29,6 +29,14 @@ struct mempolicy;
* /proc file has a parent, but "subdir" is NULL for all
* non-directory entries).
*/
+
+struct proc_sb_info {
+ struct pid_namespace *ns;
+ struct dentry *proc_self;
+ kgid_t pid_gid;
+ int hide_pid;
+};
+
struct proc_dir_entry {
unsigned int low_ino;
umode_t mode;
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 41a6ea9..5a2b6ff 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -20,6 +20,7 @@
#include <linux/mount.h>
#include <linux/pid_namespace.h>
#include <linux/parser.h>
+#include <linux/slab.h>
#include "internal.h"
@@ -31,10 +32,9 @@ static int proc_test_super(struct super_block *sb, void *data)
static int proc_set_super(struct super_block *sb, void *data)
{
int err = set_anon_super(sb, NULL);
- if (!err) {
- struct pid_namespace *ns = (struct pid_namespace *)data;
- sb->s_fs_info = get_pid_ns(ns);
- }
+ if (!err)
+ sb->s_fs_info = (struct proc_sb_info *)data;
+
return err;
}
@@ -48,7 +48,7 @@ static const match_table_t tokens = {
{Opt_err, NULL},
};
-static int proc_parse_options(char *options, struct pid_namespace *pid)
+static int proc_parse_options(char *options, struct proc_sb_info *fsi)
{
char *p;
substring_t args[MAX_OPT_ARGS];
@@ -68,7 +68,7 @@ static int proc_parse_options(char *options, struct pid_namespace *pid)
case Opt_gid:
if (match_int(&args[0], &option))
return 0;
- pid->pid_gid = make_kgid(current_user_ns(), option);
+ fsi->pid_gid = make_kgid(current_user_ns(), option);
break;
case Opt_hidepid:
if (match_int(&args[0], &option))
@@ -77,7 +77,7 @@ static int proc_parse_options(char *options, struct pid_namespace *pid)
pr_err("proc: hidepid value must be between 0 and 2.\n");
return 0;
}
- pid->hide_pid = option;
+ fsi->hide_pid = option;
break;
default:
pr_err("proc: unrecognized mount option \"%s\" "
@@ -91,36 +91,44 @@ static int proc_parse_options(char *options, struct pid_namespace *pid)
int proc_remount(struct super_block *sb, int *flags, char *data)
{
- struct pid_namespace *pid = sb->s_fs_info;
- return !proc_parse_options(data, pid);
+ struct proc_sb_info *fsi = sb->s_fs_info;
+ return !proc_parse_options(data, fsi);
}
static struct dentry *proc_mount(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data)
{
int err;
+ struct proc_sb_info *fsi;
struct super_block *sb;
- struct pid_namespace *ns;
char *options;
+
+ fsi = kzalloc(sizeof(struct proc_sb_info), GFP_KERNEL);
+ if (!fsi)
+ return ERR_PTR(-ENOMEM);
+
+ sb = sget(fs_type, proc_test_super, proc_set_super, flags, fsi);
+ if (IS_ERR(sb))
+ return ERR_CAST(sb);
if (flags & MS_KERNMOUNT) {
- ns = (struct pid_namespace *)data;
+ fsi->ns = (struct pid_namespace *)data;
+ get_pid_ns(fsi->ns);
options = NULL;
} else {
- ns = task_active_pid_ns(current);
- options = data;
-
if (!current_user_ns()->may_mount_proc)
return ERR_PTR(-EPERM);
- }
-
- sb = sget(fs_type, proc_test_super, proc_set_super, flags, ns);
- if (IS_ERR(sb))
- return ERR_CAST(sb);
+
+ options = data;
+ if (!proc_parse_options(options, fsi)) {
+ deactivate_locked_super(sb);
+ return ERR_PTR(-EINVAL);
+ }
- if (!proc_parse_options(options, ns)) {
- deactivate_locked_super(sb);
- return ERR_PTR(-EINVAL);
+ if (!fsi->ns) {
+ fsi->ns = task_active_pid_ns(current);
+ get_pid_ns(fsi->ns);
+ }
}
if (!sb->s_root) {
@@ -138,13 +146,15 @@ static struct dentry *proc_mount(struct file_system_type *fs_type,
static void proc_kill_sb(struct super_block *sb)
{
+ struct proc_sb_info *fsi;
struct pid_namespace *ns;
- ns = (struct pid_namespace *)sb->s_fs_info;
- if (ns->proc_self)
- dput(ns->proc_self);
+ fsi = (struct proc_sb_info *)sb->s_fs_info;
+ ns = (struct pid_namespace *)fsi->ns;
+ dput(fsi->proc_self);
kill_anon_super(sb);
put_pid_ns(ns);
+ kfree(fsi);
}
static struct file_system_type proc_fs_type = {
diff --git a/fs/proc/self.c b/fs/proc/self.c
index 6b6a993..ff4a2e2 100644
--- a/fs/proc/self.c
+++ b/fs/proc/self.c
@@ -10,7 +10,8 @@
static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
int buflen)
{
- struct pid_namespace *ns = dentry->d_sb->s_fs_info;
+ struct proc_sb_info *fsi = dentry->d_sb->s_fs_info;
+ struct pid_namespace *ns = fsi->ns;
pid_t tgid = task_tgid_nr_ns(current, ns);
char tmp[PROC_NUMBUF];
if (!tgid)
@@ -21,7 +22,8 @@ static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd)
{
- struct pid_namespace *ns = dentry->d_sb->s_fs_info;
+ struct proc_sb_info *fsi = dentry->d_sb->s_fs_info;
+ struct pid_namespace *ns = fsi->ns;
pid_t tgid = task_tgid_nr_ns(current, ns);
char *name = ERR_PTR(-ENOENT);
if (tgid) {
@@ -55,7 +57,7 @@ static unsigned self_inum;
int proc_setup_self(struct super_block *s)
{
struct inode *root_inode = s->s_root->d_inode;
- struct pid_namespace *ns = s->s_fs_info;
+ struct proc_sb_info *fsi = s->s_fs_info;
struct dentry *self;
mutex_lock(&root_inode->i_mutex);
@@ -82,7 +84,7 @@ int proc_setup_self(struct super_block *s)
pr_err("proc_fill_super: can't allocate /proc/self\n");
return PTR_ERR(self);
}
- ns->proc_self = self;
+ fsi->proc_self = self;
return 0;
}
diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index e277266..6185386 100644
--- a/include/linux/pid_namespace.h
+++ b/include/linux/pid_namespace.h
@@ -31,15 +31,12 @@ struct pid_namespace {
struct pid_namespace *parent;
#ifdef CONFIG_PROC_FS
struct vfsmount *proc_mnt;
- struct dentry *proc_self;
#endif
#ifdef CONFIG_BSD_PROCESS_ACCT
struct bsd_acct_struct *bacct;
#endif
struct user_namespace *user_ns;
struct work_struct proc_work;
- kgid_t pid_gid;
- int hide_pid;
int reboot; /* group exit code if this pidns was rebooted */
unsigned int proc_inum;
};
--
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