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Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH 13/32] proc: Add fs_context support to procfs [ver #8] From: David Howells To: viro@zeniv.linux.org.uk Cc: dhowells@redhat.com, linux-fsdevel@vger.kernel.org, linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org Date: Fri, 25 May 2018 01:06:48 +0100 Message-ID: <152720680880.9073.13644233876944936872.stgit@warthog.procyon.org.uk> In-Reply-To: <152720672288.9073.9868393448836301272.stgit@warthog.procyon.org.uk> References: <152720672288.9073.9868393448836301272.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Fri, 25 May 2018 00:06:50 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Fri, 25 May 2018 00:06:50 +0000 (UTC) for IP:'10.11.54.5' DOMAIN:'int-mx05.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'dhowells@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add fs_context support to procfs. Signed-off-by: David Howells --- 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 #include #include +#include #include #include #include #include #include +#include #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);