LXR linux/fs/squashfs/xattr.c

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * Squashfs - a compressed read only filesystem for Linux
   4 *
   5 * Copyright (c) 2010
   6 * Phillip Lougher <phillip@squashfs.org.uk>
   7 *
   8 * xattr.c
   9 */
  10
  11#include <linux/init.h>
  12#include <linux/module.h>
  13#include <linux/string.h>
  14#include <linux/fs.h>
  15#include <linux/vfs.h>
  16#include <linux/xattr.h>
  17#include <linux/slab.h>
  18
  19#include "squashfs_fs.h"
  20#include "squashfs_fs_sb.h"
  21#include "squashfs_fs_i.h"
  22#include "squashfs.h"
  23
  24static const struct xattr_handler *squashfs_xattr_handler(int);
  25
  26ssize_t squashfs_listxattr(struct dentry *d, char *buffer,
  27        size_t buffer_size)
  28{
  29        struct inode *inode = d_inode(d);
  30        struct super_block *sb = inode->i_sb;
  31        struct squashfs_sb_info *msblk = sb->s_fs_info;
  32        u64 start = SQUASHFS_XATTR_BLK(squashfs_i(inode)->xattr)
  33                                                 + msblk->xattr_table;
  34        int offset = SQUASHFS_XATTR_OFFSET(squashfs_i(inode)->xattr);
  35        int count = squashfs_i(inode)->xattr_count;
  36        size_t rest = buffer_size;
  37        int err;
  38
  39        /* check that the file system has xattrs */
  40        if (msblk->xattr_id_table == NULL)
  41                return -EOPNOTSUPP;
  42
  43        /* loop reading each xattr name */
  44        while (count--) {
  45                struct squashfs_xattr_entry entry;
  46                struct squashfs_xattr_val val;
  47                const struct xattr_handler *handler;
  48                int name_size;
  49
  50                err = squashfs_read_metadata(sb, &entry, &start, &offset,
  51                                                        sizeof(entry));
  52                if (err < 0)
  53                        goto failed;
  54
  55                name_size = le16_to_cpu(entry.size);
  56                handler = squashfs_xattr_handler(le16_to_cpu(entry.type));
  57                if (handler && (!handler->list || handler->list(d))) {
  58                        const char *prefix = handler->prefix ?: handler->name;
  59                        size_t prefix_size = strlen(prefix);
  60
  61                        if (buffer) {
  62                                if (prefix_size + name_size + 1 > rest) {
  63                                        err = -ERANGE;
  64                                        goto failed;
  65                                }
  66                                memcpy(buffer, prefix, prefix_size);
  67                                buffer += prefix_size;
  68                        }
  69                        err = squashfs_read_metadata(sb, buffer, &start,
  70                                &offset, name_size);
  71                        if (err < 0)
  72                                goto failed;
  73                        if (buffer) {
  74                                buffer[name_size] = '\0';
  75                                buffer += name_size + 1;
  76                        }
  77                        rest -= prefix_size + name_size + 1;
  78                } else  {
  79                        /* no handler or insuffficient privileges, so skip */
  80                        err = squashfs_read_metadata(sb, NULL, &start,
  81                                &offset, name_size);
  82                        if (err < 0)
  83                                goto failed;
  84                }
  85
  86
  87                /* skip remaining xattr entry */
  88                err = squashfs_read_metadata(sb, &val, &start, &offset,
  89                                                sizeof(val));
  90                if (err < 0)
  91                        goto failed;
  92
  93                err = squashfs_read_metadata(sb, NULL, &start, &offset,
  94                                                le32_to_cpu(val.vsize));
  95                if (err < 0)
  96                        goto failed;
  97        }
  98        err = buffer_size - rest;
  99
 100failed:
 101        return err;
 102}
 103
 104
 105static int squashfs_xattr_get(struct inode *inode, int name_index,
 106        const char *name, void *buffer, size_t buffer_size)
 107{
 108        struct super_block *sb = inode->i_sb;
 109        struct squashfs_sb_info *msblk = sb->s_fs_info;
 110        u64 start = SQUASHFS_XATTR_BLK(squashfs_i(inode)->xattr)
 111                                                 + msblk->xattr_table;
 112        int offset = SQUASHFS_XATTR_OFFSET(squashfs_i(inode)->xattr);
 113        int count = squashfs_i(inode)->xattr_count;
 114        int name_len = strlen(name);
 115        int err, vsize;
 116        char *target = kmalloc(name_len, GFP_KERNEL);
 117
 118        if (target == NULL)
 119                return  -ENOMEM;
 120
 121        /* loop reading each xattr name */
 122        for (; count; count--) {
 123                struct squashfs_xattr_entry entry;
 124                struct squashfs_xattr_val val;
 125                int type, prefix, name_size;
 126
 127                err = squashfs_read_metadata(sb, &entry, &start, &offset,
 128                                                        sizeof(entry));
 129                if (err < 0)
 130                        goto failed;
 131
 132                name_size = le16_to_cpu(entry.size);
 133                type = le16_to_cpu(entry.type);
 134                prefix = type & SQUASHFS_XATTR_PREFIX_MASK;
 135
 136                if (prefix == name_index && name_size == name_len)
 137                        err = squashfs_read_metadata(sb, target, &start,
 138                                                &offset, name_size);
 139                else
 140                        err = squashfs_read_metadata(sb, NULL, &start,
 141                                                &offset, name_size);
 142                if (err < 0)
 143                        goto failed;
 144
 145                if (prefix == name_index && name_size == name_len &&
 146                                        strncmp(target, name, name_size) == 0) {
 147                        /* found xattr */
 148                        if (type & SQUASHFS_XATTR_VALUE_OOL) {
 149                                __le64 xattr_val;
 150                                u64 xattr;
 151                                /* val is a reference to the real location */
 152                                err = squashfs_read_metadata(sb, &val, &start,
 153                                                &offset, sizeof(val));
 154                                if (err < 0)
 155                                        goto failed;
 156                                err = squashfs_read_metadata(sb, &xattr_val,
 157                                        &start, &offset, sizeof(xattr_val));
 158                                if (err < 0)
 159                                        goto failed;
 160                                xattr = le64_to_cpu(xattr_val);
 161                                start = SQUASHFS_XATTR_BLK(xattr) +
 162                                                        msblk->xattr_table;
 163                                offset = SQUASHFS_XATTR_OFFSET(xattr);
 164                        }
 165                        /* read xattr value */
 166                        err = squashfs_read_metadata(sb, &val, &start, &offset,
 167                                                        sizeof(val));
 168                        if (err < 0)
 169                                goto failed;
 170
 171                        vsize = le32_to_cpu(val.vsize);
 172                        if (buffer) {
 173                                if (vsize > buffer_size) {
 174                                        err = -ERANGE;
 175                                        goto failed;
 176                                }
 177                                err = squashfs_read_metadata(sb, buffer, &start,
 178                                         &offset, vsize);
 179                                if (err < 0)
 180                                        goto failed;
 181                        }
 182                        break;
 183                }
 184
 185                /* no match, skip remaining xattr entry */
 186                err = squashfs_read_metadata(sb, &val, &start, &offset,
 187                                                        sizeof(val));
 188                if (err < 0)
 189                        goto failed;
 190                err = squashfs_read_metadata(sb, NULL, &start, &offset,
 191                                                le32_to_cpu(val.vsize));
 192                if (err < 0)
 193                        goto failed;
 194        }
 195        err = count ? vsize : -ENODATA;
 196
 197failed:
 198        kfree(target);
 199        return err;
 200}
 201
 202
 203static int squashfs_xattr_handler_get(const struct xattr_handler *handler,
 204                                      struct dentry *unused,
 205                                      struct inode *inode,
 206                                      const char *name,
 207                                      void *buffer, size_t size)
 208{
 209        return squashfs_xattr_get(inode, handler->flags, name,
 210                buffer, size);
 211}
 212
 213/*
 214 * User namespace support
 215 */
 216static const struct xattr_handler squashfs_xattr_user_handler = {
 217        .prefix = XATTR_USER_PREFIX,
 218        .flags  = SQUASHFS_XATTR_USER,
 219        .get    = squashfs_xattr_handler_get
 220};
 221
 222/*
 223 * Trusted namespace support
 224 */
 225static bool squashfs_trusted_xattr_handler_list(struct dentry *d)
 226{
 227        return capable(CAP_SYS_ADMIN);
 228}
 229
 230static const struct xattr_handler squashfs_xattr_trusted_handler = {
 231        .prefix = XATTR_TRUSTED_PREFIX,
 232        .flags  = SQUASHFS_XATTR_TRUSTED,
 233        .list   = squashfs_trusted_xattr_handler_list,
 234        .get    = squashfs_xattr_handler_get
 235};
 236
 237/*
 238 * Security namespace support
 239 */
 240static const struct xattr_handler squashfs_xattr_security_handler = {
 241        .prefix = XATTR_SECURITY_PREFIX,
 242        .flags  = SQUASHFS_XATTR_SECURITY,
 243        .get    = squashfs_xattr_handler_get
 244};
 245
 246static const struct xattr_handler *squashfs_xattr_handler(int type)
 247{
 248        if (type & ~(SQUASHFS_XATTR_PREFIX_MASK | SQUASHFS_XATTR_VALUE_OOL))
 249                /* ignore unrecognised type */
 250                return NULL;
 251
 252        switch (type & SQUASHFS_XATTR_PREFIX_MASK) {
 253        case SQUASHFS_XATTR_USER:
 254                return &squashfs_xattr_user_handler;
 255        case SQUASHFS_XATTR_TRUSTED:
 256                return &squashfs_xattr_trusted_handler;
 257        case SQUASHFS_XATTR_SECURITY:
 258                return &squashfs_xattr_security_handler;
 259        default:
 260                /* ignore unrecognised type */
 261                return NULL;
 262        }
 263}
 264
 265const struct xattr_handler *squashfs_xattr_handlers[] = {
 266        &squashfs_xattr_user_handler,
 267        &squashfs_xattr_trusted_handler,
 268        &squashfs_xattr_security_handler,
 269        NULL
 270};
 271
 272