proc: add and remove /proc entry create checks

* remove proc_create(NULL, ...) check, let it oops

* warn about proc_create("", ...) and proc_create("very very long name", ...)
  proc code keeps length as u8, no 256+ name length possible

* warn about proc_create("123", ...)
  /proc/$PID and /proc/misc namespaces are separate things,
  but dumb module might create funky a-la $PID entry.

* remove post mortem strchr('/') check
  Triggering it implies either strchr() is buggy or memory corruption.
  It should be VFS check anyway.

In reality, none of these checks will ever trigger,
it is preparation for the next patch.

Based on patch from Al Viro.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 79df9ff71afdfec224e86c925a5dab65aa025229..11375216b493b7ac69f3d994c8b9990e0e138c8a 100644 (file)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2785,7 +2785,7 @@ struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, unsign
        unsigned tgid;
        struct pid_namespace *ns;
 
-       tgid = name_to_int(dentry);
+       tgid = name_to_int(&dentry->d_name);
        if (tgid == ~0U)
                goto out;
 
@@ -3033,7 +3033,7 @@ static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry
        if (!leader)
                goto out_no_task;
 
-       tid = name_to_int(dentry);
+       tid = name_to_int(&dentry->d_name);
        if (tid == ~0U)
                goto out;
 

diff --git a/fs/proc/fd.c b/fs/proc/fd.c
index 0788d093f5d86ace99ad80f68f4d7bd924eff294..955bb55fab8cad3fbdfbd8e69f5536e6c2e53593 100644 (file)
--- a/fs/proc/fd.c
+++ b/fs/proc/fd.c
@@ -206,7 +206,7 @@ static struct dentry *proc_lookupfd_common(struct inode *dir,
 {
        struct task_struct *task = get_proc_task(dir);
        int result = -ENOENT;
-       unsigned fd = name_to_int(dentry);
+       unsigned fd = name_to_int(&dentry->d_name);
 
        if (!task)
                goto out_no_task;

diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index b7f268eb5f45251ae1977c643540e081c6612546..190862e8988059bc53c4fce415dd3b113703c623 100644 (file)
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -330,28 +330,28 @@ static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent,
                                          nlink_t nlink)
 {
        struct proc_dir_entry *ent = NULL;
-       const char *fn = name;
-       unsigned int len;
-
-       /* make sure name is valid */
-       if (!name || !strlen(name))
-               goto out;
+       const char *fn;
+       struct qstr qstr;
 
        if (xlate_proc_name(name, parent, &fn) != 0)
                goto out;
+       qstr.name = fn;
+       qstr.len = strlen(fn);
+       if (qstr.len == 0 || qstr.len >= 256) {
+               WARN(1, "name len %u\n", qstr.len);
+               return NULL;
+       }
+       if (*parent == &proc_root && name_to_int(&qstr) != ~0U) {
+               WARN(1, "create '/proc/%s' by hand\n", qstr.name);
+               return NULL;
+       }
 
-       /* At this point there must not be any '/' characters beyond *fn */
-       if (strchr(fn, '/'))
-               goto out;
-
-       len = strlen(fn);
-
-       ent = kzalloc(sizeof(struct proc_dir_entry) + len + 1, GFP_KERNEL);
+       ent = kzalloc(sizeof(struct proc_dir_entry) + qstr.len + 1, GFP_KERNEL);
        if (!ent)
                goto out;
 
-       memcpy(ent->name, fn, len + 1);
-       ent->namelen = len;
+       memcpy(ent->name, fn, qstr.len + 1);
+       ent->namelen = qstr.len;
        ent->mode = mode;
        ent->nlink = nlink;
        atomic_set(&ent->count, 1);

diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index 3ab6d14e71c544753e0558fd78022a63200ea644..a38408a1dd84b577bbf6ddafeb6ae49d78a2a235 100644 (file)
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -112,10 +112,10 @@ static inline int task_dumpable(struct task_struct *task)
        return 0;
 }
 
-static inline unsigned name_to_int(struct dentry *dentry)
+static inline unsigned name_to_int(const struct qstr *qstr)
 {
-       const char *name = dentry->d_name.name;
-       int len = dentry->d_name.len;
+       const char *name = qstr->name;
+       int len = qstr->len;
        unsigned n = 0;
 
        if (len > 1 && *name == '0')