proc_namespace.c

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    1 /*
    2  * fs/proc_namespace.c - handling of /proc/<pid>/{mounts,mountinfo,mountstats}
    3  *
    4  * In fact, that's a piece of procfs; it's *almost* isolated from
    5  * the rest of fs/proc, but has rather close relationships with
    6  * fs/namespace.c, thus here instead of fs/proc
    7  *
    8  */
    9 #include <linux/mnt_namespace.h>
   10 #include <linux/nsproxy.h>
   11 #include <linux/security.h>
   12 #include <linux/fs_struct.h>
   13 #include "proc/internal.h" /* only for get_proc_task() in ->open() */
   14 
   15 #include "pnode.h"
   16 #include "internal.h"
   17 
   18 static unsigned mounts_poll(struct file *file, poll_table *wait)
   19 {
   20         struct proc_mounts *p = proc_mounts(file->private_data);
   21         struct mnt_namespace *ns = p->ns;
   22         unsigned res = POLLIN | POLLRDNORM;
   23 
   24         poll_wait(file, &p->ns->poll, wait);
   25 
   26         br_read_lock(&vfsmount_lock);
   27         if (p->m.poll_event != ns->event) {
   28                 p->m.poll_event = ns->event;
   29                 res |= POLLERR | POLLPRI;
   30         }
   31         br_read_unlock(&vfsmount_lock);
   32 
   33         return res;
   34 }
   35 
   36 struct proc_fs_info {
   37         int flag;
   38         const char *str;
   39 };
   40 
   41 static int show_sb_opts(struct seq_file *m, struct super_block *sb)
   42 {
   43         static const struct proc_fs_info fs_info[] = {
   44                 { MS_SYNCHRONOUS, ",sync" },
   45                 { MS_DIRSYNC, ",dirsync" },
   46                 { MS_MANDLOCK, ",mand" },
   47                 { 0, NULL }
   48         };
   49         const struct proc_fs_info *fs_infop;
   50 
   51         for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
   52                 if (sb->s_flags & fs_infop->flag)
   53                         seq_puts(m, fs_infop->str);
   54         }
   55 
   56         return security_sb_show_options(m, sb);
   57 }
   58 
   59 static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt)
   60 {
   61         static const struct proc_fs_info mnt_info[] = {
   62                 { MNT_NOSUID, ",nosuid" },
   63                 { MNT_NODEV, ",nodev" },
   64                 { MNT_NOEXEC, ",noexec" },
   65                 { MNT_NOATIME, ",noatime" },
   66                 { MNT_NODIRATIME, ",nodiratime" },
   67                 { MNT_RELATIME, ",relatime" },
   68                 { 0, NULL }
   69         };
   70         const struct proc_fs_info *fs_infop;
   71 
   72         for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) {
   73                 if (mnt->mnt_flags & fs_infop->flag)
   74                         seq_puts(m, fs_infop->str);
   75         }
   76 }
   77 
   78 static inline void mangle(struct seq_file *m, const char *s)
   79 {
   80         seq_escape(m, s, " \t\n\\");
   81 }
   82 
   83 static void show_type(struct seq_file *m, struct super_block *sb)
   84 {
   85         mangle(m, sb->s_type->name);
   86         if (sb->s_subtype && sb->s_subtype[0]) {
   87                 seq_putc(m, '.');
   88                 mangle(m, sb->s_subtype);
   89         }
   90 }
   91 
   92 static int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt)
   93 {
   94         struct mount *r = real_mount(mnt);
   95         int err = 0;
   96         struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
   97         struct super_block *sb = mnt_path.dentry->d_sb;
   98 
   99         if (sb->s_op->show_devname) {
  100                 err = sb->s_op->show_devname(m, mnt_path.dentry);
  101                 if (err)
  102                         goto out;
  103         } else {
  104                 mangle(m, r->mnt_devname ? r->mnt_devname : "none");
  105         }
  106         seq_putc(m, ' ');
  107         seq_path(m, &mnt_path, " \t\n\\");
  108         seq_putc(m, ' ');
  109         show_type(m, sb);
  110         seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
  111         err = show_sb_opts(m, sb);
  112         if (err)
  113                 goto out;
  114         show_mnt_opts(m, mnt);
  115         if (sb->s_op->show_options)
  116                 err = sb->s_op->show_options(m, mnt_path.dentry);
  117         seq_puts(m, " 0 0\n");
  118 out:
  119         return err;
  120 }
  121 
  122 static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt)
  123 {
  124         struct proc_mounts *p = proc_mounts(m);
  125         struct mount *r = real_mount(mnt);
  126         struct super_block *sb = mnt->mnt_sb;
  127         struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
  128         struct path root = p->root;
  129         int err = 0;
  130 
  131         seq_printf(m, "%i %i %u:%u ", r->mnt_id, r->mnt_parent->mnt_id,
  132                    MAJOR(sb->s_dev), MINOR(sb->s_dev));
  133         if (sb->s_op->show_path)
  134                 err = sb->s_op->show_path(m, mnt->mnt_root);
  135         else
  136                 seq_dentry(m, mnt->mnt_root, " \t\n\\");
  137         if (err)
  138                 goto out;
  139         seq_putc(m, ' ');
  140 
  141         /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
  142         err = seq_path_root(m, &mnt_path, &root, " \t\n\\");
  143         if (err)
  144                 goto out;
  145 
  146         seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
  147         show_mnt_opts(m, mnt);
  148 
  149         /* Tagged fields ("foo:X" or "bar") */
  150         if (IS_MNT_SHARED(r))
  151                 seq_printf(m, " shared:%i", r->mnt_group_id);
  152         if (IS_MNT_SLAVE(r)) {
  153                 int master = r->mnt_master->mnt_group_id;
  154                 int dom = get_dominating_id(r, &p->root);
  155                 seq_printf(m, " master:%i", master);
  156                 if (dom && dom != master)
  157                         seq_printf(m, " propagate_from:%i", dom);
  158         }
  159         if (IS_MNT_UNBINDABLE(r))
  160                 seq_puts(m, " unbindable");
  161 
  162         /* Filesystem specific data */
  163         seq_puts(m, " - ");
  164         show_type(m, sb);
  165         seq_putc(m, ' ');
  166         if (sb->s_op->show_devname)
  167                 err = sb->s_op->show_devname(m, mnt->mnt_root);
  168         else
  169                 mangle(m, r->mnt_devname ? r->mnt_devname : "none");
  170         if (err)
  171                 goto out;
  172         seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw");
  173         err = show_sb_opts(m, sb);
  174         if (err)
  175                 goto out;
  176         if (sb->s_op->show_options)
  177                 err = sb->s_op->show_options(m, mnt->mnt_root);
  178         seq_putc(m, '\n');
  179 out:
  180         return err;
  181 }
  182 
  183 static int show_vfsstat(struct seq_file *m, struct vfsmount *mnt)
  184 {
  185         struct mount *r = real_mount(mnt);
  186         struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
  187         struct super_block *sb = mnt_path.dentry->d_sb;
  188         int err = 0;
  189 
  190         /* device */
  191         if (sb->s_op->show_devname) {
  192                 seq_puts(m, "device ");
  193                 err = sb->s_op->show_devname(m, mnt_path.dentry);
  194         } else {
  195                 if (r->mnt_devname) {
  196                         seq_puts(m, "device ");
  197                         mangle(m, r->mnt_devname);
  198                 } else
  199                         seq_puts(m, "no device");
  200         }
  201 
  202         /* mount point */
  203         seq_puts(m, " mounted on ");
  204         seq_path(m, &mnt_path, " \t\n\\");
  205         seq_putc(m, ' ');
  206 
  207         /* file system type */
  208         seq_puts(m, "with fstype ");
  209         show_type(m, sb);
  210 
  211         /* optional statistics */
  212         if (sb->s_op->show_stats) {
  213                 seq_putc(m, ' ');
  214                 if (!err)
  215                         err = sb->s_op->show_stats(m, mnt_path.dentry);
  216         }
  217 
  218         seq_putc(m, '\n');
  219         return err;
  220 }
  221 
  222 static int mounts_open_common(struct inode *inode, struct file *file,
  223                               int (*show)(struct seq_file *, struct vfsmount *))
  224 {
  225         struct task_struct *task = get_proc_task(inode);
  226         struct nsproxy *nsp;
  227         struct mnt_namespace *ns = NULL;
  228         struct path root;
  229         struct proc_mounts *p;
  230         int ret = -EINVAL;
  231 
  232         if (!task)
  233                 goto err;
  234 
  235         rcu_read_lock();
  236         nsp = task_nsproxy(task);
  237         if (!nsp) {
  238                 rcu_read_unlock();
  239                 put_task_struct(task);
  240                 goto err;
  241         }
  242         ns = nsp->mnt_ns;
  243         if (!ns) {
  244                 rcu_read_unlock();
  245                 put_task_struct(task);
  246                 goto err;
  247         }
  248         get_mnt_ns(ns);
  249         rcu_read_unlock();
  250         task_lock(task);
  251         if (!task->fs) {
  252                 task_unlock(task);
  253                 put_task_struct(task);
  254                 ret = -ENOENT;
  255                 goto err_put_ns;
  256         }
  257         get_fs_root(task->fs, &root);
  258         task_unlock(task);
  259         put_task_struct(task);
  260 
  261         ret = -ENOMEM;
  262         p = kmalloc(sizeof(struct proc_mounts), GFP_KERNEL);
  263         if (!p)
  264                 goto err_put_path;
  265 
  266         file->private_data = &p->m;
  267         ret = seq_open(file, &mounts_op);
  268         if (ret)
  269                 goto err_free;
  270 
  271         p->ns = ns;
  272         p->root = root;
  273         p->m.poll_event = ns->event;
  274         p->show = show;
  275 
  276         return 0;
  277 
  278  err_free:
  279         kfree(p);
  280  err_put_path:
  281         path_put(&root);
  282  err_put_ns:
  283         put_mnt_ns(ns);
  284  err:
  285         return ret;
  286 }
  287 
  288 static int mounts_release(struct inode *inode, struct file *file)
  289 {
  290         struct proc_mounts *p = proc_mounts(file->private_data);
  291         path_put(&p->root);
  292         put_mnt_ns(p->ns);
  293         return seq_release(inode, file);
  294 }
  295 
  296 static int mounts_open(struct inode *inode, struct file *file)
  297 {
  298         return mounts_open_common(inode, file, show_vfsmnt);
  299 }
  300 
  301 static int mountinfo_open(struct inode *inode, struct file *file)
  302 {
  303         return mounts_open_common(inode, file, show_mountinfo);
  304 }
  305 
  306 static int mountstats_open(struct inode *inode, struct file *file)
  307 {
  308         return mounts_open_common(inode, file, show_vfsstat);
  309 }
  310 
  311 const struct file_operations proc_mounts_operations = {
  312         .open           = mounts_open,
  313         .read           = seq_read,
  314         .llseek         = seq_lseek,
  315         .release        = mounts_release,
  316         .poll           = mounts_poll,
  317 };
  318 
  319 const struct file_operations proc_mountinfo_operations = {
  320         .open           = mountinfo_open,
  321         .read           = seq_read,
  322         .llseek         = seq_lseek,
  323         .release        = mounts_release,
  324         .poll           = mounts_poll,
  325 };
  326 
  327 const struct file_operations proc_mountstats_operations = {
  328         .open           = mountstats_open,
  329         .read           = seq_read,
  330         .llseek         = seq_lseek,
  331         .release        = mounts_release,
  332 };
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FreeBSD/Linux Kernel Cross Reference sys/fs/proc_namespace.c

FreeBSD/Linux Kernel Cross Reference
sys/fs/proc_namespace.c
