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    Subject[PATCH 8/9] proc: Support the mount context in procfs
    From
    Date

    ---

    fs/proc/inode.c | 2 -
    fs/proc/internal.h | 2 -
    fs/proc/root.c | 158 ++++++++++++++++++++++++++++++++--------------------
    3 files changed, 100 insertions(+), 62 deletions(-)

    diff --git a/fs/proc/inode.c b/fs/proc/inode.c
    index 194fa2d13b7e..9ddaf60c6f93 100644
    --- a/fs/proc/inode.c
    +++ b/fs/proc/inode.c
    @@ -118,7 +118,7 @@ const struct super_operations proc_sops = {
    .drop_inode = generic_delete_inode,
    .evict_inode = proc_evict_inode,
    .statfs = simple_statfs,
    - .remount_fs = proc_remount,
    + .remount_fs_mc = proc_remount,
    .show_options = proc_show_options,
    };

    diff --git a/fs/proc/internal.h b/fs/proc/internal.h
    index b681533f59dd..68b693478e7e 100644
    --- a/fs/proc/internal.h
    +++ b/fs/proc/internal.h
    @@ -262,7 +262,7 @@ 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 *);
    +extern int proc_remount(struct super_block *, struct mount_context *);

    /*
    * task_[no]mmu.c
    diff --git a/fs/proc/root.c b/fs/proc/root.c
    index ff2e810e9e64..132529a5e896 100644
    --- a/fs/proc/root.c
    +++ b/fs/proc/root.c
    @@ -23,9 +23,17 @@
    #include <linux/parser.h>
    #include <linux/cred.h>
    #include <linux/magic.h>
    +#include <linux/slab.h>

    #include "internal.h"

    +struct proc_mount_context {
    + struct mount_context mc;
    + unsigned long mask;
    + int hidepid;
    + int gid;
    +};
    +
    enum {
    Opt_gid, Opt_hidepid, Opt_err,
    };
    @@ -36,56 +44,68 @@ static const match_table_t tokens = {
    {Opt_err, NULL},
    };

    -static int proc_parse_options(char *options, struct pid_namespace *pid)
    +static int proc_mount_option(struct mount_context *mc, char *p)
    {
    - char *p;
    + struct proc_mount_context *ctx =
    + container_of(mc, struct proc_mount_context, mc);
    substring_t args[MAX_OPT_ARGS];
    - int option;
    -
    - if (!options)
    - return 1;
    -
    - while ((p = strsep(&options, ",")) != NULL) {
    - int token;
    - if (!*p)
    - continue;
    -
    - 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;
    + int token;
    +
    + args[0].to = args[0].from = NULL;
    + token = match_token(p, tokens, args);
    + switch (token) {
    + case Opt_gid:
    + if (match_int(&args[0], &ctx->gid)) {
    + mc->error = "procfs: Unparseable gid= argument";
    + return -EINVAL;
    + }
    + break;
    +
    + case Opt_hidepid:
    + if (match_int(&args[0], &ctx->hidepid)) {
    + mc->error = "procfs: Unparseable hidepid= argument";
    + return -EINVAL;
    }
    + if (ctx->hidepid < HIDEPID_OFF ||
    + ctx->hidepid > HIDEPID_INVISIBLE) {
    + mc->error = "procfs: Invalid hidepid= argument";
    + pr_err("proc: hidepid value must be between 0 and 2.\n");
    + return -EINVAL;
    + }
    + break;
    +
    + default:
    + pr_err("proc: unrecognized mount option \"%s\" "
    + "or missing value\n", p);
    + mc->error = "procfs: Invalid mount option or missing value";
    + return -EINVAL;
    }

    - return 1;
    + ctx->mask |= 1 << token;
    + return 0;
    }

    -static int proc_fill_super(struct super_block *s, void *data, int silent)
    +static void proc_set_options(struct super_block *s,
    + struct mount_context *mc,
    + struct pid_namespace *pid_ns,
    + struct user_namespace *user_ns)
    {
    - struct pid_namespace *ns = get_pid_ns(s->s_fs_info);
    + struct proc_mount_context *ctx =
    + container_of(mc, struct proc_mount_context, mc);
    +
    + 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 mount_context *mc)
    +{
    + 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_set_options(s, mc, 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;
    @@ -102,7 +122,7 @@ static int proc_fill_super(struct super_block *s, void *data, int silent)
    * top of it
    */
    s->s_stack_depth = FILESYSTEM_MAX_STACK_DEPTH;
    -
    +
    pde_get(&proc_root);
    root_inode = proc_get_inode(s, &proc_root);
    if (!root_inode) {
    @@ -123,27 +143,32 @@ 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)
    +int proc_remount(struct super_block *sb, struct mount_context *mc)
    {
    struct pid_namespace *pid = sb->s_fs_info;

    sync_filesystem(sb);
    - return !proc_parse_options(data, pid);
    +
    + if (mc)
    + proc_set_options(sb, mc, 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 struct dentry *proc_mount(struct mount_context *mc)
    {
    - struct pid_namespace *ns;
    + return mount_ns_mc(mc, mc->pid_ns);
    +}

    - if (flags & MS_KERNMOUNT) {
    - ns = data;
    - data = NULL;
    - } else {
    - ns = task_active_pid_ns(current);
    - }
    +static const struct mount_context_operations proc_mount_ctx_ops = {
    + .option = proc_mount_option,
    + .mount = proc_mount,
    + .fill_super = proc_fill_super,
    +};

    - return mount_ns(fs_type, flags, data, ns, ns->user_ns, proc_fill_super);
    +static int proc_fsopen(struct mount_context *mc, struct super_block *src_sb)
    +{
    + mc->ops = &proc_mount_ctx_ops;
    + return 0;
    }

    static void proc_kill_sb(struct super_block *sb)
    @@ -161,7 +186,8 @@ static void proc_kill_sb(struct super_block *sb)

    static struct file_system_type proc_fs_type = {
    .name = "proc",
    - .mount = proc_mount,
    + .fsopen = proc_fsopen,
    + .mc_size = sizeof(struct proc_mount_context),
    .kill_sb = proc_kill_sb,
    .fs_flags = FS_USERNS_MOUNT,
    };
    @@ -209,7 +235,7 @@ 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);
    }

    @@ -248,12 +274,12 @@ static const struct inode_operations proc_root_inode_operations = {
    * This is the root "inode" in the /proc tree..
    */
    struct proc_dir_entry proc_root = {
    - .low_ino = PROC_ROOT_INO,
    - .namelen = 5,
    - .mode = S_IFDIR | S_IRUGO | S_IXUGO,
    - .nlink = 2,
    + .low_ino = PROC_ROOT_INO,
    + .namelen = 5,
    + .mode = S_IFDIR | S_IRUGO | S_IXUGO,
    + .nlink = 2,
    .count = ATOMIC_INIT(1),
    - .proc_iops = &proc_root_inode_operations,
    + .proc_iops = &proc_root_inode_operations,
    .proc_fops = &proc_root_operations,
    .parent = &proc_root,
    .subdir = RB_ROOT,
    @@ -262,9 +288,21 @@ struct proc_dir_entry proc_root = {

    int pid_ns_prepare_proc(struct pid_namespace *ns)
    {
    + struct mount_context *mc;
    struct vfsmount *mnt;

    - mnt = kern_mount_data(&proc_fs_type, ns);
    + mc = __vfs_fsopen(&proc_fs_type, NULL, 0, 0, MOUNT_TYPE_NEW);
    + if (IS_ERR(mc))
    + return PTR_ERR(mc);
    +
    + if (mc->pid_ns != ns) {
    + put_pid_ns(mc->pid_ns);
    + get_pid_ns(ns);
    + mc->pid_ns = ns;
    + }
    +
    + mnt = kern_mount_data_mc(mc);
    + put_mount_context(mc);
    if (IS_ERR(mnt))
    return PTR_ERR(mnt);

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      Last update: 2017-05-03 18:07    [W:4.263 / U:0.144 seconds]
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