--- /dev/null
+/*
+ * /proc/uid support
+ */
+
+#include <linux/fs.h>
+#include <linux/hashtable.h>
+#include <linux/init.h>
+#include <linux/proc_fs.h>
+#include <linux/rtmutex.h>
+#include <linux/sched.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+#include "internal.h"
+
+static struct proc_dir_entry *proc_uid;
+
+#define UID_HASH_BITS 10
+
+static DECLARE_HASHTABLE(proc_uid_hash_table, UID_HASH_BITS);
+
+/*
+ * use rt_mutex here to avoid priority inversion between high-priority readers
+ * of these files and tasks calling proc_register_uid().
+ */
+static DEFINE_RT_MUTEX(proc_uid_lock); /* proc_uid_hash_table */
+
+struct uid_hash_entry {
+ uid_t uid;
+ struct hlist_node hash;
+};
+
+/* Caller must hold proc_uid_lock */
+static bool uid_hash_entry_exists_locked(uid_t uid)
+{
+ struct uid_hash_entry *entry;
+
+ hash_for_each_possible(proc_uid_hash_table, entry, hash, uid) {
+ if (entry->uid == uid)
+ return true;
+ }
+ return false;
+}
+
+void proc_register_uid(kuid_t kuid)
+{
+ struct uid_hash_entry *entry;
+ bool exists;
+ uid_t uid = from_kuid_munged(current_user_ns(), kuid);
+
+ rt_mutex_lock(&proc_uid_lock);
+ exists = uid_hash_entry_exists_locked(uid);
+ rt_mutex_unlock(&proc_uid_lock);
+ if (exists)
+ return;
+
+ entry = kzalloc(sizeof(struct uid_hash_entry), GFP_KERNEL);
+ if (!entry)
+ return;
+ entry->uid = uid;
+
+ rt_mutex_lock(&proc_uid_lock);
+ if (uid_hash_entry_exists_locked(uid))
+ kfree(entry);
+ else
+ hash_add(proc_uid_hash_table, &entry->hash, uid);
+ rt_mutex_unlock(&proc_uid_lock);
+}
+
+struct uid_entry {
+ const char *name;
+ int len;
+ umode_t mode;
+ const struct inode_operations *iop;
+ const struct file_operations *fop;
+};
+
+#define NOD(NAME, MODE, IOP, FOP) { \
+ .name = (NAME), \
+ .len = sizeof(NAME) - 1, \
+ .mode = MODE, \
+ .iop = IOP, \
+ .fop = FOP, \
+}
+
+static const struct uid_entry uid_base_stuff[] = {};
+
+static const struct inode_operations proc_uid_def_inode_operations = {
+ .setattr = proc_setattr,
+};
+
+static struct inode *proc_uid_make_inode(struct super_block *sb, kuid_t kuid)
+{
+ struct inode *inode;
+
+ inode = new_inode(sb);
+ if (!inode)
+ return NULL;
+
+ inode->i_ino = get_next_ino();
+ inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
+ inode->i_op = &proc_uid_def_inode_operations;
+ inode->i_uid = kuid;
+
+ return inode;
+}
+
+static int proc_uident_instantiate(struct inode *dir, struct dentry *dentry,
+ struct task_struct *unused, const void *ptr)
+{
+ const struct uid_entry *u = ptr;
+ struct inode *inode;
+
+ inode = proc_uid_make_inode(dir->i_sb, dir->i_uid);
+ if (!inode)
+ return -ENOENT;
+
+ inode->i_mode = u->mode;
+ if (S_ISDIR(inode->i_mode))
+ set_nlink(inode, 2);
+ if (u->iop)
+ inode->i_op = u->iop;
+ if (u->fop)
+ inode->i_fop = u->fop;
+ d_add(dentry, inode);
+ return 0;
+}
+
+static struct dentry *proc_uid_base_lookup(struct inode *dir,
+ struct dentry *dentry,
+ unsigned int flags)
+{
+ const struct uid_entry *u, *last;
+ unsigned int nents = ARRAY_SIZE(uid_base_stuff);
+
+ if (nents == 0)
+ return ERR_PTR(-ENOENT);
+
+ last = &uid_base_stuff[nents - 1];
+ for (u = uid_base_stuff; u <= last; u++) {
+ if (u->len != dentry->d_name.len)
+ continue;
+ if (!memcmp(dentry->d_name.name, u->name, u->len))
+ break;
+ }
+ if (u > last)
+ return ERR_PTR(-ENOENT);
+
+ return ERR_PTR(proc_uident_instantiate(dir, dentry, NULL, u));
+}
+
+static int proc_uid_base_readdir(struct file *file, struct dir_context *ctx)
+{
+ unsigned int nents = ARRAY_SIZE(uid_base_stuff);
+ const struct uid_entry *u;
+
+ if (!dir_emit_dots(file, ctx))
+ return 0;
+
+ if (ctx->pos >= nents + 2)
+ return 0;
+
+ for (u = uid_base_stuff + (ctx->pos - 2);
+ u <= uid_base_stuff + nents - 1; u++) {
+ if (!proc_fill_cache(file, ctx, u->name, u->len,
+ proc_uident_instantiate, NULL, u))
+ break;
+ ctx->pos++;
+ }
+
+ return 0;
+}
+
+static const struct inode_operations proc_uid_base_inode_operations = {
+ .lookup = proc_uid_base_lookup,
+ .setattr = proc_setattr,
+};
+
+static const struct file_operations proc_uid_base_operations = {
+ .read = generic_read_dir,
+ .iterate = proc_uid_base_readdir,
+ .llseek = default_llseek,
+};
+
+static int proc_uid_instantiate(struct inode *dir, struct dentry *dentry,
+ struct task_struct *unused, const void *ptr)
+{
+ unsigned int i, len;
+ nlink_t nlinks;
+ kuid_t *kuid = (kuid_t *)ptr;
+ struct inode *inode = proc_uid_make_inode(dir->i_sb, *kuid);
+
+ if (!inode)
+ return -ENOENT;
+
+ inode->i_mode = S_IFDIR | 0555;
+ inode->i_op = &proc_uid_base_inode_operations;
+ inode->i_fop = &proc_uid_base_operations;
+ inode->i_flags |= S_IMMUTABLE;
+
+ nlinks = 2;
+ len = ARRAY_SIZE(uid_base_stuff);
+ for (i = 0; i < len; ++i) {
+ if (S_ISDIR(uid_base_stuff[i].mode))
+ ++nlinks;
+ }
+ set_nlink(inode, nlinks);
+
+ d_add(dentry, inode);
+
+ return 0;
+}
+
+static int proc_uid_readdir(struct file *file, struct dir_context *ctx)
+{
+ int last_shown, i;
+ unsigned long bkt;
+ struct uid_hash_entry *entry;
+
+ if (!dir_emit_dots(file, ctx))
+ return 0;
+
+ i = 0;
+ last_shown = ctx->pos - 2;
+ rt_mutex_lock(&proc_uid_lock);
+ hash_for_each(proc_uid_hash_table, bkt, entry, hash) {
+ int len;
+ char buf[PROC_NUMBUF];
+
+ if (i < last_shown)
+ continue;
+ len = snprintf(buf, sizeof(buf), "%u", entry->uid);
+ if (!proc_fill_cache(file, ctx, buf, len,
+ proc_uid_instantiate, NULL, &entry->uid))
+ break;
+ i++;
+ ctx->pos++;
+ }
+ rt_mutex_unlock(&proc_uid_lock);
+ return 0;
+}
+
+static struct dentry *proc_uid_lookup(struct inode *dir, struct dentry *dentry,
+ unsigned int flags)
+{
+ int result = -ENOENT;
+
+ uid_t uid = name_to_int(&dentry->d_name);
+ bool uid_exists;
+
+ rt_mutex_lock(&proc_uid_lock);
+ uid_exists = uid_hash_entry_exists_locked(uid);
+ rt_mutex_unlock(&proc_uid_lock);
+ if (uid_exists) {
+ kuid_t kuid = make_kuid(current_user_ns(), uid);
+
+ result = proc_uid_instantiate(dir, dentry, NULL, &kuid);
+ }
+ return ERR_PTR(result);
+}
+
+static const struct file_operations proc_uid_operations = {
+ .read = generic_read_dir,
+ .iterate = proc_uid_readdir,
+ .llseek = default_llseek,
+};
+
+static const struct inode_operations proc_uid_inode_operations = {
+ .lookup = proc_uid_lookup,
+ .setattr = proc_setattr,
+};
+
+int __init proc_uid_init(void)
+{
+ proc_uid = proc_mkdir("uid", NULL);
+ if (!proc_uid)
+ return -ENOMEM;
+ proc_uid->proc_iops = &proc_uid_inode_operations;
+ proc_uid->proc_fops = &proc_uid_operations;
+
+ return 0;
+}
projects / GitHub / moto-9609 / android_kernel_motorola_exynos9610.git / commitdiff