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    Subject[PATCH 13/32] proc: Add fs_context support to procfs [ver #8]
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    Date
    Add fs_context support to procfs.

    Signed-off-by: David Howells <dhowells@redhat.com>
    ---

    fs/proc/inode.c | 2 -
    fs/proc/internal.h | 2 -
    fs/proc/root.c | 179 ++++++++++++++++++++++++++++++++++------------------
    3 files changed, 120 insertions(+), 63 deletions(-)

    diff --git a/fs/proc/inode.c b/fs/proc/inode.c
    index 0b13cf6eb6d7..7aa86dd65ba8 100644
    --- a/fs/proc/inode.c
    +++ b/fs/proc/inode.c
    @@ -128,7 +128,7 @@ const struct super_operations proc_sops = {
    .drop_inode = generic_delete_inode,
    .evict_inode = proc_evict_inode,
    .statfs = simple_statfs,
    - .remount_fs = proc_remount,
    + .reconfigure = proc_reconfigure,
    .show_options = proc_show_options,
    };

    diff --git a/fs/proc/internal.h b/fs/proc/internal.h
    index c918ec4cc0d9..77254851327c 100644
    --- a/fs/proc/internal.h
    +++ b/fs/proc/internal.h
    @@ -265,7 +265,7 @@ 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 *, size_t);
    +extern int proc_reconfigure(struct super_block *, struct fs_context *);

    /*
    * task_[no]mmu.c
    diff --git a/fs/proc/root.c b/fs/proc/root.c
    index 2fbc177f37a8..a379edccd880 100644
    --- a/fs/proc/root.c
    +++ b/fs/proc/root.c
    @@ -19,14 +19,23 @@
    #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/cred.h>
    #include <linux/magic.h>
    +#include <linux/slab.h>

    #include "internal.h"

    +struct proc_fs_context {
    + struct pid_namespace *pid_ns;
    + unsigned long mask;
    + int hidepid;
    + int gid;
    +};
    +
    enum {
    Opt_gid, Opt_hidepid, Opt_err,
    };
    @@ -37,56 +46,60 @@ static const match_table_t tokens = {
    {Opt_err, NULL},
    };

    -static int proc_parse_options(char *options, struct pid_namespace *pid)
    +static int proc_parse_option(struct fs_context *fc, char *opt, size_t len)
    {
    - char *p;
    + struct proc_fs_context *ctx = fc->fs_private;
    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(opt, tokens, args);
    + switch (token) {
    + case Opt_gid:
    + if (match_int(&args[0], &ctx->gid))
    + return -EINVAL;
    + break;
    +
    + case Opt_hidepid:
    + if (match_int(&args[0], &ctx->hidepid))
    + return -EINVAL;
    + if (ctx->hidepid < HIDEPID_OFF ||
    + ctx->hidepid > HIDEPID_INVISIBLE) {
    + 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",
    + opt);
    + return -EINVAL;
    }

    - return 1;
    + ctx->mask |= 1 << token;
    + return 0;
    +}
    +
    +static void proc_set_options(struct super_block *s,
    + struct fs_context *fc,
    + struct pid_namespace *pid_ns,
    + struct user_namespace *user_ns)
    +{
    + 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, void *data, size_t data_size, int silent)
    +static int proc_fill_super(struct super_block *s, struct fs_context *fc)
    {
    - struct pid_namespace *ns = get_pid_ns(s->s_fs_info);
    + 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, 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;
    @@ -103,7 +116,7 @@ static int proc_fill_super(struct super_block *s, void *data, size_t data_size,
    * 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) {
    @@ -124,30 +137,52 @@ static int proc_fill_super(struct super_block *s, void *data, size_t data_size,
    return proc_setup_thread_self(s);
    }

    -int proc_remount(struct super_block *sb, int *flags,
    - char *data, size_t data_size)
    +int proc_reconfigure(struct super_block *sb, struct fs_context *fc)
    {
    struct pid_namespace *pid = sb->s_fs_info;

    sync_filesystem(sb);
    - return !proc_parse_options(data, pid);
    +
    + if (fc)
    + proc_set_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, size_t data_size)
    +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);
    - }
    + fc->s_fs_info = ctx->pid_ns;
    + return vfs_get_super(fc, vfs_get_keyed_super, 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_option = proc_parse_option,
    + .get_tree = proc_get_tree,
    +};

    - return mount_ns(fs_type, flags, data, data_size, ns, ns->user_ns,
    - proc_fill_super);
    +static int proc_init_fs_context(struct fs_context *fc, struct dentry *reference)
    +{
    + 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 +199,10 @@ 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,
    + .kill_sb = proc_kill_sb,
    + .fs_flags = FS_USERNS_MOUNT,
    };

    void __init proc_root_init(void)
    @@ -205,7 +240,7 @@ 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);
    }

    @@ -259,9 +294,31 @@ 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;
    + int ret;
    +
    + fc = vfs_new_fs_context(&proc_fs_type, NULL, 0,
    + FS_CONTEXT_FOR_KERNEL_MOUNT);
    + if (IS_ERR(fc))
    + return PTR_ERR(fc);
    +
    + ctx = fc->fs_private;
    + if (ctx->pid_ns != ns) {
    + put_pid_ns(ctx->pid_ns);
    + get_pid_ns(ns);
    + ctx->pid_ns = ns;
    + }
    +
    + ret = vfs_get_tree(fc);
    + if (ret < 0) {
    + put_fs_context(fc);
    + return ret;
    + }

    - mnt = kern_mount_data(&proc_fs_type, ns, 0);
    + mnt = vfs_create_mount(fc, 0);
    + put_fs_context(fc);
    if (IS_ERR(mnt))
    return PTR_ERR(mnt);

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      Last update: 2018-05-25 02:13    [W:4.259 / U:0.060 seconds]
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