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TOMOYO Linux Cross Reference
Linux/fs/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 <linux/sched/task.h>
 14 
 15 #include "<proc/internal.h" /* only for get_proc_task() in -?v=linux-4.11.12;a=mips">a href="source/fs/proc/internal.h?v=linux-4.11.12;a=mips">proc/internal.h" /* only for get_proc_task() in ->open() */
 16 
 17 #include "pnode.h"
 18 #include "internal.h"
 19 
 20 static unsigned mounts_poll(struct file *file, poll_table *wait)
 21 {
 22         struct seq_file *m = file->private_data;
 23         struct proc_mounts *p = m->private;
 24         struct mnt_namespace *ns = p->ns;
 25         unsigned res = POLLIN | POLLRDNORM;
 26         int event;
 27 
 28         poll_wait(file, &p->ns->poll, wait);
 29 
 30         event = ACCESS_ONCE(ns->event);
 31         if (m->poll_event != event) {
 32                 m->poll_event = event;
 33                 res |= POLLERR | POLLPRI;
 34         }
 35 
 36         return res;
 37 }
 38 
 39 struct proc_fs_info {
 40         int flag;
 41         const char *str;
 42 };
 43 
 44 static int show_sb_opts(struct seq_file *m, struct super_block *sb)
 45 {
 46         static const struct proc_fs_info fs_info[] = {
 47                 { MS_SYNCHRONOUS, ",sync" },
 48                 { MS_DIRSYNC, ",dirsync" },
 49                 { MS_MANDLOCK, ",mand" },
 50                 { MS_LAZYTIME, ",lazytime" },
 51                 { 0, NULL }
 52         };
 53         const struct proc_fs_info *fs_infop;
 54 
 55         for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
 56                 if (sb->s_flags & fs_infop->flag)
 57                         seq_puts(m, fs_infop->str);
 58         }
 59 
 60         return security_sb_show_options(m, sb);
 61 }
 62 
 63 static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt)
 64 {
 65         static const struct proc_fs_info mnt_info[] = {
 66                 { MNT_NOSUID, ",nosuid" },
 67                 { MNT_NODEV, ",nodev" },
 68                 { MNT_NOEXEC, ",noexec" },
 69                 { MNT_NOATIME, ",noatime" },
 70                 { MNT_NODIRATIME, ",nodiratime" },
 71                 { MNT_RELATIME, ",relatime" },
 72                 { 0, NULL }
 73         };
 74         const struct proc_fs_info *fs_infop;
 75 
 76         for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) {
 77                 if (mnt->mnt_flags & fs_infop->flag)
 78                         seq_puts(m, fs_infop->str);
 79         }
 80 }
 81 
 82 static inline void mangle(struct seq_file *m, const char *s)
 83 {
 84         seq_escape(m, s, " \t\n\\");
 85 }
 86 
 87 static void show_type(struct seq_file *m, struct super_block *sb)
 88 {
 89         mangle(m, sb->s_type->name);
 90         if (sb->s_subtype && sb->s_subtype[0]) {
 91                 seq_putc(m, '.');
 92                 mangle(m, sb->s_subtype);
 93         }
 94 }
 95 
 96 static int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt)
 97 {
 98         struct proc_mounts *p = m->private;
 99         struct mount *r = real_mount(mnt);
100         struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
101         struct super_block *sb = mnt_path.dentry->d_sb;
102         int err;
103 
104         if (sb->s_op->show_devname) {
105                 err = sb->s_op->show_devname(m, mnt_path.dentry);
106                 if (err)
107                         goto out;
108         } else {
109                 mangle(m, r->mnt_devname ? r->mnt_devname : "none");
110         }
111         seq_putc(m, ' ');
112         /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
113         err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
114         if (err)
115                 goto out;
116         seq_putc(m, ' ');
117         show_type(m, sb);
118         seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
119         err = show_sb_opts(m, sb);
120         if (err)
121                 goto out;
122         show_mnt_opts(m, mnt);
123         if (sb->s_op->show_options)
124                 err = sb->s_op->show_options(m, mnt_path.dentry);
125         seq_puts(m, " 0 0\n");
126 out:
127         return err;
128 }
129 
130 static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt)
131 {
132         struct proc_mounts *p = m->private;
133         struct mount *r = real_mount(mnt);
134         struct super_block *sb = mnt->mnt_sb;
135         struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
136         int err;
137 
138         seq_printf(m, "%i %i %u:%u ", r->mnt_id, r->mnt_parent->mnt_id,
139                    MAJOR(sb->s_dev), MINOR(sb->s_dev));
140         if (sb->s_op->show_path) {
141                 err = sb->s_op->show_path(m, mnt->mnt_root);
142                 if (err)
143                         goto out;
144         } else {
145                 seq_dentry(m, mnt->mnt_root, " \t\n\\");
146         }
147         seq_putc(m, ' ');
148 
149         /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
150         err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
151         if (err)
152                 goto out;
153 
154         seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
155         show_mnt_opts(m, mnt);
156 
157         /* Tagged fields ("foo:X" or "bar") */
158         if (IS_MNT_SHARED(r))
159                 seq_printf(m, " shared:%i", r->mnt_group_id);
160         if (IS_MNT_SLAVE(r)) {
161                 int master = r->mnt_master->mnt_group_id;
162                 int dom = get_dominating_id(r, &p->root);
163                 seq_printf(m, " master:%i", master);
164                 if (dom && dom != master)
165                         seq_printf(m, " propagate_from:%i", dom);
166         }
167         if (IS_MNT_UNBINDABLE(r))
168                 seq_puts(m, " unbindable");
169 
170         /* Filesystem specific data */
171         seq_puts(m, " - ");
172         show_type(m, sb);
173         seq_putc(m, ' ');
174         if (sb->s_op->show_devname) {
175                 err = sb->s_op->show_devname(m, mnt->mnt_root);
176                 if (err)
177                         goto out;
178         } else {
179                 mangle(m, r->mnt_devname ? r->mnt_devname : "none");
180         }
181         seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw");
182         err = show_sb_opts(m, sb);
183         if (err)
184                 goto out;
185         if (sb->s_op->show_options)
186                 err = sb->s_op->show_options(m, mnt->mnt_root);
187         seq_putc(m, '\n');
188 out:
189         return err;
190 }
191 
192 static int show_vfsstat(struct seq_file *m, struct vfsmount *mnt)
193 {
194         struct proc_mounts *p = m->private;
195         struct mount *r = real_mount(mnt);
196         struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
197         struct super_block *sb = mnt_path.dentry->d_sb;
198         int err;
199 
200         /* device */
201         if (sb->s_op->show_devname) {
202                 seq_puts(m, "device ");
203                 err = sb->s_op->show_devname(m, mnt_path.dentry);
204                 if (err)
205                         goto out;
206         } else {
207                 if (r->mnt_devname) {
208                         seq_puts(m, "device ");
209                         mangle(m, r->mnt_devname);
210                 } else
211                         seq_puts(m, "no device");
212         }
213 
214         /* mount point */
215         seq_puts(m, " mounted on ");
216         /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
217         err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
218         if (err)
219                 goto out;
220         seq_putc(m, ' ');
221 
222         /* file system type */
223         seq_puts(m, "with fstype ");
224         show_type(m, sb);
225 
226         /* optional statistics */
227         if (sb->s_op->show_stats) {
228                 seq_putc(m, ' ');
229                 err = sb->s_op->show_stats(m, mnt_path.dentry);
230         }
231 
232         seq_putc(m, '\n');
233 out:
234         return err;
235 }
236 
237 static int mounts_open_common(struct inode *inode, struct file *file,
238                               int (*show)(struct seq_file *, struct vfsmount *))
239 {
240         struct task_struct *task = get_proc_task(inode);
241         struct nsproxy *nsp;
242         struct mnt_namespace *ns = NULL;
243         struct path root;
244         struct proc_mounts *p;
245         struct seq_file *m;
246         int ret = -EINVAL;
247 
248         if (!task)
249                 goto err;
250 
251         task_lock(task);
252         nsp = task->nsproxy;
253         if (!nsp || !nsp->mnt_ns) {
254                 task_unlock(task);
255                 put_task_struct(task);
256                 goto err;
257         }
258         ns = nsp->mnt_ns;
259         get_mnt_ns(ns);
260         if (!task->fs) {
261                 task_unlock(task);
262                 put_task_struct(task);
263                 ret = -ENOENT;
264                 goto err_put_ns;
265         }
266         get_fs_root(task->fs, &root);
267         task_unlock(task);
268         put_task_struct(task);
269 
270         ret = seq_open_private(file, &mounts_op, sizeof(struct proc_mounts));
271         if (ret)
272                 goto err_put_path;
273 
274         m = file->private_data;
275         m->poll_event = ns->event;
276 
277         p = m->private;
278         p->ns = ns;
279         p->root = root;
280         p->show = show;
281         p->cached_event = ~0ULL;
282 
283         return 0;
284 
285  err_put_path:
286         path_put(&root);
287  err_put_ns:
288         put_mnt_ns(ns);
289  err:
290         return ret;
291 }
292 
293 static int mounts_release(struct inode *inode, struct file *file)
294 {
295         struct seq_file *m = file->private_data;
296         struct proc_mounts *p = m->private;
297         path_put(&p->root);
298         put_mnt_ns(p->ns);
299         return seq_release_private(inode, file);
300 }
301 
302 static int mounts_open(struct inode *inode, struct file *file)
303 {
304         return mounts_open_common(inode, file, show_vfsmnt);
305 }
306 
307 static int mountinfo_open(struct inode *inode, struct file *file)
308 {
309         return mounts_open_common(inode, file, show_mountinfo);
310 }
311 
312 static int mountstats_open(struct inode *inode, struct file *file)
313 {
314         return mounts_open_common(inode, file, show_vfsstat);
315 }
316 
317 const struct file_operations proc_mounts_operations = {
318         .open           = mounts_open,
319         .read           = seq_read,
320         .llseek         = seq_lseek,
321         .release        = mounts_release,
322         .poll           = mounts_poll,
323 };
324 
325 const struct file_operations proc_mountinfo_operations = {
326         .open           = mountinfo_open,
327         .read           = seq_read,
328         .llseek         = seq_lseek,
329         .release        = mounts_release,
330         .poll           = mounts_poll,
331 };
332 
333 const struct file_operations proc_mountstats_operations = {
334         .open           = mountstats_open,
335         .read           = seq_read,
336         .llseek         = seq_lseek,
337         .release        = mounts_release,
338 };
339 

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