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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 "<proc/internal.h" /* only for get_proc_task() in -?v=linux-4.1.52">a href="source/fs/proc/internal.h?v=linux-4.1.52">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         int event;
 24 
 25         poll_wait(file, &p->ns->poll, wait);
 26 
 27         event = ACCESS_ONCE(ns->event);
 28         if (p->m.poll_event != event) {
 29                 p->m.poll_event = event;
 30                 res |= POLLERR | POLLPRI;
 31         }
 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                 { MS_LAZYTIME, ",lazytime" },
 48                 { 0, NULL }
 49         };
 50         const struct proc_fs_info *fs_infop;
 51 
 52         for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
 53                 if (sb->s_flags & fs_infop->flag)
 54                         seq_puts(m, fs_infop->str);
 55         }
 56 
 57         return security_sb_show_options(m, sb);
 58 }
 59 
 60 static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt)
 61 {
 62         static const struct proc_fs_info mnt_info[] = {
 63                 { MNT_NOSUID, ",nosuid" },
 64                 { MNT_NODEV, ",nodev" },
 65                 { MNT_NOEXEC, ",noexec" },
 66                 { MNT_NOATIME, ",noatime" },
 67                 { MNT_NODIRATIME, ",nodiratime" },
 68                 { MNT_RELATIME, ",relatime" },
 69                 { 0, NULL }
 70         };
 71         const struct proc_fs_info *fs_infop;
 72 
 73         for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) {
 74                 if (mnt->mnt_flags & fs_infop->flag)
 75                         seq_puts(m, fs_infop->str);
 76         }
 77 }
 78 
 79 static inline void mangle(struct seq_file *m, const char *s)
 80 {
 81         seq_escape(m, s, " \t\n\\");
 82 }
 83 
 84 static void show_type(struct seq_file *m, struct super_block *sb)
 85 {
 86         mangle(m, sb->s_type->name);
 87         if (sb->s_subtype && sb->s_subtype[0]) {
 88                 seq_putc(m, '.');
 89                 mangle(m, sb->s_subtype);
 90         }
 91 }
 92 
 93 static int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt)
 94 {
 95         struct proc_mounts *p = proc_mounts(m);
 96         struct mount *r = real_mount(mnt);
 97         int err = 0;
 98         struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
 99         struct super_block *sb = mnt_path.dentry->d_sb;
100 
101         if (sb->s_op->show_devname) {
102                 err = sb->s_op->show_devname(m, mnt_path.dentry);
103                 if (err)
104                         goto out;
105         } else {
106                 mangle(m, r->mnt_devname ? r->mnt_devname : "none");
107         }
108         seq_putc(m, ' ');
109         /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
110         err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
111         if (err)
112                 goto out;
113         seq_putc(m, ' ');
114         show_type(m, sb);
115         seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
116         err = show_sb_opts(m, sb);
117         if (err)
118                 goto out;
119         show_mnt_opts(m, mnt);
120         if (sb->s_op->show_options)
121                 err = sb->s_op->show_options(m, mnt_path.dentry);
122         seq_puts(m, " 0 0\n");
123 out:
124         return err;
125 }
126 
127 static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt)
128 {
129         struct proc_mounts *p = proc_mounts(m);
130         struct mount *r = real_mount(mnt);
131         struct super_block *sb = mnt->mnt_sb;
132         struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
133         int err = 0;
134 
135         seq_printf(m, "%i %i %u:%u ", r->mnt_id, r->mnt_parent->mnt_id,
136                    MAJOR(sb->s_dev), MINOR(sb->s_dev));
137         if (sb->s_op->show_path)
138                 err = sb->s_op->show_path(m, mnt->mnt_root);
139         else
140                 seq_dentry(m, mnt->mnt_root, " \t\n\\");
141         if (err)
142                 goto out;
143         seq_putc(m, ' ');
144 
145         /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
146         err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
147         if (err)
148                 goto out;
149 
150         seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw");
151         show_mnt_opts(m, mnt);
152 
153         /* Tagged fields ("foo:X" or "bar") */
154         if (IS_MNT_SHARED(r))
155                 seq_printf(m, " shared:%i", r->mnt_group_id);
156         if (IS_MNT_SLAVE(r)) {
157                 int master = r->mnt_master->mnt_group_id;
158                 int dom = get_dominating_id(r, &p->root);
159                 seq_printf(m, " master:%i", master);
160                 if (dom && dom != master)
161                         seq_printf(m, " propagate_from:%i", dom);
162         }
163         if (IS_MNT_UNBINDABLE(r))
164                 seq_puts(m, " unbindable");
165 
166         /* Filesystem specific data */
167         seq_puts(m, " - ");
168         show_type(m, sb);
169         seq_putc(m, ' ');
170         if (sb->s_op->show_devname)
171                 err = sb->s_op->show_devname(m, mnt->mnt_root);
172         else
173                 mangle(m, r->mnt_devname ? r->mnt_devname : "none");
174         if (err)
175                 goto out;
176         seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw");
177         err = show_sb_opts(m, sb);
178         if (err)
179                 goto out;
180         if (sb->s_op->show_options)
181                 err = sb->s_op->show_options(m, mnt->mnt_root);
182         seq_putc(m, '\n');
183 out:
184         return err;
185 }
186 
187 static int show_vfsstat(struct seq_file *m, struct vfsmount *mnt)
188 {
189         struct proc_mounts *p = proc_mounts(m);
190         struct mount *r = real_mount(mnt);
191         struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
192         struct super_block *sb = mnt_path.dentry->d_sb;
193         int err = 0;
194 
195         /* device */
196         if (sb->s_op->show_devname) {
197                 seq_puts(m, "device ");
198                 err = sb->s_op->show_devname(m, mnt_path.dentry);
199                 if (err)
200                         goto out;
201         } else {
202                 if (r->mnt_devname) {
203                         seq_puts(m, "device ");
204                         mangle(m, r->mnt_devname);
205                 } else
206                         seq_puts(m, "no device");
207         }
208 
209         /* mount point */
210         seq_puts(m, " mounted on ");
211         /* mountpoints outside of chroot jail will give SEQ_SKIP on this */
212         err = seq_path_root(m, &mnt_path, &p->root, " \t\n\\");
213         if (err)
214                 goto out;
215         seq_putc(m, ' ');
216 
217         /* file system type */
218         seq_puts(m, "with fstype ");
219         show_type(m, sb);
220 
221         /* optional statistics */
222         if (sb->s_op->show_stats) {
223                 seq_putc(m, ' ');
224                 if (!err)
225                         err = sb->s_op->show_stats(m, mnt_path.dentry);
226         }
227 
228         seq_putc(m, '\n');
229 out:
230         return err;
231 }
232 
233 static int mounts_open_common(struct inode *inode, struct file *file,
234                               int (*show)(struct seq_file *, struct vfsmount *))
235 {
236         struct task_struct *task = get_proc_task(inode);
237         struct nsproxy *nsp;
238         struct mnt_namespace *ns = NULL;
239         struct path root;
240         struct proc_mounts *p;
241         int ret = -EINVAL;
242 
243         if (!task)
244                 goto err;
245 
246         task_lock(task);
247         nsp = task->nsproxy;
248         if (!nsp || !nsp->mnt_ns) {
249                 task_unlock(task);
250                 put_task_struct(task);
251                 goto err;
252         }
253         ns = nsp->mnt_ns;
254         get_mnt_ns(ns);
255         if (!task->fs) {
256                 task_unlock(task);
257                 put_task_struct(task);
258                 ret = -ENOENT;
259                 goto err_put_ns;
260         }
261         get_fs_root(task->fs, &root);
262         task_unlock(task);
263         put_task_struct(task);
264 
265         ret = -ENOMEM;
266         p = kmalloc(sizeof(struct proc_mounts), GFP_KERNEL);
267         if (!p)
268                 goto err_put_path;
269 
270         file->private_data = &p->m;
271         ret = seq_open(file, &mounts_op);
272         if (ret)
273                 goto err_free;
274 
275         p->ns = ns;
276         p->root = root;
277         p->m.poll_event = ns->event;
278         p->show = show;
279         p->cached_event = ~0ULL;
280 
281         return 0;
282 
283  err_free:
284         kfree(p);
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 proc_mounts *p = proc_mounts(file->private_data);
296         path_put(&p->root);
297         put_mnt_ns(p->ns);
298         return seq_release(inode, file);
299 }
300 
301 static int mounts_open(struct inode *inode, struct file *file)
302 {
303         return mounts_open_common(inode, file, show_vfsmnt);
304 }
305 
306 static int mountinfo_open(struct inode *inode, struct file *file)
307 {
308         return mounts_open_common(inode, file, show_mountinfo);
309 }
310 
311 static int mountstats_open(struct inode *inode, struct file *file)
312 {
313         return mounts_open_common(inode, file, show_vfsstat);
314 }
315 
316 const struct file_operations proc_mounts_operations = {
317         .open           = mounts_open,
318         .read           = seq_read,
319         .llseek         = seq_lseek,
320         .release        = mounts_release,
321         .poll           = mounts_poll,
322 };
323 
324 const struct file_operations proc_mountinfo_operations = {
325         .open           = mountinfo_open,
326         .read           = seq_read,
327         .llseek         = seq_lseek,
328         .release        = mounts_release,
329         .poll           = mounts_poll,
330 };
331 
332 const struct file_operations proc_mountstats_operations = {
333         .open           = mountstats_open,
334         .read           = seq_read,
335         .llseek         = seq_lseek,
336         .release        = mounts_release,
337 };
338 

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