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proc: Add fs_context support to procfs 

Add fs_context support to procfs.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
David Howells 2018-11-01 23:07:25 +00:00 committed by Al Viro
parent 60a3c3a58e
commit 66f592e2ec
3 changed files with 126 additions and 65 deletions
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1
fs/proc/inode.c
View File

@ -127,7 +127,6 @@ const struct super_operations proc_sops = {
.drop_inode = generic_delete_inode,
.evict_inode = proc_evict_inode,
.statfs = simple_statfs,
.remount_fs = proc_remount,
.show_options = proc_show_options,
};

1
fs/proc/internal.h
View File

@ -270,7 +270,6 @@ static inline void proc_tty_init(void) {}
extern struct proc_dir_entry proc_root;
extern void proc_self_init(void);
extern int proc_remount(struct super_block *, int *, char *);
/*
* task_[no]mmu.c

189
fs/proc/root.c
View File

@ -19,74 +19,89 @@
#include <linux/module.h>
#include <linux/bitops.h>
#include <linux/user_namespace.h>
#include <linux/fs_context.h>
#include <linux/mount.h>
#include <linux/pid_namespace.h>
#include <linux/parser.h>
#include <linux/fs_parser.h>
#include <linux/cred.h>
#include <linux/magic.h>
#include <linux/slab.h>
#include "internal.h"
enum {
Opt_gid, Opt_hidepid, Opt_err,
struct proc_fs_context {
struct pid_namespace *pid_ns;
unsigned int mask;
int hidepid;
int gid;
};
static const match_table_t tokens = {
{Opt_hidepid, "hidepid=%u"},
{Opt_gid, "gid=%u"},
{Opt_err, NULL},
enum proc_param {
Opt_gid,
Opt_hidepid,
};
static int proc_parse_options(char *options, struct pid_namespace *pid)
static const struct fs_parameter_spec proc_param_specs[] = {
fsparam_u32("gid", Opt_gid),
fsparam_u32("hidepid", Opt_hidepid),
{}
};
static const struct fs_parameter_description proc_fs_parameters = {
.name = "proc",
.specs = proc_param_specs,
};
static int proc_parse_param(struct fs_context *fc, struct fs_parameter *param)
{
char *p;
substring_t args[MAX_OPT_ARGS];
int option;
struct proc_fs_context *ctx = fc->fs_private;
struct fs_parse_result result;
int opt;
if (!options)
return 1;
opt = fs_parse(fc, &proc_fs_parameters, param, &result);
if (opt < 0)
return opt;
while ((p = strsep(&options, ",")) != NULL) {
int token;
if (!*p)
continue;
switch (opt) {
case Opt_gid:
ctx->gid = result.uint_32;
break;
args[0].to = args[0].from = NULL;
token = match_token(p, tokens, args);
switch (token) {
case Opt_gid:
if (match_int(&args[0], &option))
return 0;
pid->pid_gid = make_kgid(current_user_ns(), option);
break;
case Opt_hidepid:
if (match_int(&args[0], &option))
return 0;
if (option < HIDEPID_OFF ||
option > HIDEPID_INVISIBLE) {
pr_err("proc: hidepid value must be between 0 and 2.\n");
return 0;
}
pid->hide_pid = option;
break;
default:
pr_err("proc: unrecognized mount option \"%s\" "
"or missing value\n", p);
return 0;
}
case Opt_hidepid:
ctx->hidepid = result.uint_32;
if (ctx->hidepid < HIDEPID_OFF ||
ctx->hidepid > HIDEPID_INVISIBLE)
return invalf(fc, "proc: hidepid value must be between 0 and 2.\n");
break;
default:
return -EINVAL;
}
return 1;
ctx->mask |= 1 << opt;
return 0;
}
static int proc_fill_super(struct super_block *s, void *data, int silent)
static void proc_apply_options(struct super_block *s,
struct fs_context *fc,
struct pid_namespace *pid_ns,
struct user_namespace *user_ns)
{
struct pid_namespace *ns = get_pid_ns(s->s_fs_info);
struct proc_fs_context *ctx = fc->fs_private;
if (ctx->mask & (1 << Opt_gid))
pid_ns->pid_gid = make_kgid(user_ns, ctx->gid);
if (ctx->mask & (1 << Opt_hidepid))
pid_ns->hide_pid = ctx->hidepid;
}
static int proc_fill_super(struct super_block *s, struct fs_context *fc)
{
struct pid_namespace *pid_ns = get_pid_ns(s->s_fs_info);
struct inode *root_inode;
int ret;
if (!proc_parse_options(data, ns))
return -EINVAL;
proc_apply_options(s, fc, pid_ns, current_user_ns());
/* User space would break if executables or devices appear on proc */
s->s_iflags |= SB_I_USERNS_VISIBLE | SB_I_NOEXEC | SB_I_NODEV;
@ -127,27 +142,55 @@ static int proc_fill_super(struct super_block *s, void *data, int silent)
return proc_setup_thread_self(s);
}
int proc_remount(struct super_block *sb, int *flags, char *data)
static int proc_reconfigure(struct fs_context *fc)
{
struct super_block *sb = fc->root->d_sb;
struct pid_namespace *pid = sb->s_fs_info;
sync_filesystem(sb);
return !proc_parse_options(data, pid);
proc_apply_options(sb, fc, pid, current_user_ns());
return 0;
}
static struct dentry *proc_mount(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data)
static int proc_get_tree(struct fs_context *fc)
{
struct pid_namespace *ns;
struct proc_fs_context *ctx = fc->fs_private;
if (flags & SB_KERNMOUNT) {
ns = data;
data = NULL;
} else {
ns = task_active_pid_ns(current);
}
put_user_ns(fc->user_ns);
fc->user_ns = get_user_ns(ctx->pid_ns->user_ns);
fc->s_fs_info = ctx->pid_ns;
return vfs_get_super(fc, vfs_get_keyed_super, proc_fill_super);
}
return mount_ns(fs_type, flags, data, ns, ns->user_ns, proc_fill_super);
static void proc_fs_context_free(struct fs_context *fc)
{
struct proc_fs_context *ctx = fc->fs_private;
if (ctx->pid_ns)
put_pid_ns(ctx->pid_ns);
kfree(ctx);
}
static const struct fs_context_operations proc_fs_context_ops = {
.free = proc_fs_context_free,
.parse_param = proc_parse_param,
.get_tree = proc_get_tree,
.reconfigure = proc_reconfigure,
};
static int proc_init_fs_context(struct fs_context *fc)
{
struct proc_fs_context *ctx;
ctx = kzalloc(sizeof(struct proc_fs_context), GFP_KERNEL);
if (!ctx)
return -ENOMEM;
ctx->pid_ns = get_pid_ns(task_active_pid_ns(current));
fc->fs_private = ctx;
fc->ops = &proc_fs_context_ops;
return 0;
}
static void proc_kill_sb(struct super_block *sb)
@ -164,10 +207,11 @@ static void proc_kill_sb(struct super_block *sb)
}
static struct file_system_type proc_fs_type = {
.name = "proc",
.mount = proc_mount,
.kill_sb = proc_kill_sb,
.fs_flags = FS_USERNS_MOUNT,
.name = "proc",
.init_fs_context = proc_init_fs_context,
.parameters = &proc_fs_parameters,
.kill_sb = proc_kill_sb,
.fs_flags = FS_USERNS_MOUNT,
};
void __init proc_root_init(void)
@ -205,7 +249,7 @@ static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentr
{
if (!proc_pid_lookup(dir, dentry, flags))
return NULL;
return proc_lookup(dir, dentry, flags);
}
@ -258,9 +302,28 @@ struct proc_dir_entry proc_root = {
int pid_ns_prepare_proc(struct pid_namespace *ns)
{
struct proc_fs_context *ctx;
struct fs_context *fc;
struct vfsmount *mnt;
mnt = kern_mount_data(&proc_fs_type, ns);
fc = fs_context_for_mount(&proc_fs_type, SB_KERNMOUNT);
if (IS_ERR(fc))
return PTR_ERR(fc);
if (fc->user_ns != ns->user_ns) {
put_user_ns(fc->user_ns);
fc->user_ns = get_user_ns(ns->user_ns);
}
ctx = fc->fs_private;
if (ctx->pid_ns != ns) {
put_pid_ns(ctx->pid_ns);
get_pid_ns(ns);
ctx->pid_ns = ns;
}
mnt = fc_mount(fc);
put_fs_context(fc);
if (IS_ERR(mnt))
return PTR_ERR(mnt);