src/shared/smack-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2 /***
   3   Copyright © 2013 Intel Corporation
   4
   5   Author: Auke Kok <auke-jan.h.kok@intel.com>
   6 ***/
   7
   8 #include <errno.h>
   9 #include <fcntl.h>
  10 #include <sys/stat.h>
  11 #include <sys/xattr.h>
  12 #include <unistd.h>
  13
  14 #include "alloc-util.h"
  15 #include "errno-util.h"
  16 #include "fd-util.h"
  17 #include "fileio.h"
  18 #include "log.h"
  19 #include "macro.h"
  20 #include "path-util.h"
  21 #include "process-util.h"
  22 #include "smack-util.h"
  23 #include "stdio-util.h"
  24 #include "string-table.h"
  25 #include "xattr-util.h"
  26
  27 #if ENABLE_SMACK
  28 bool mac_smack_use(void) {
  29         static int cached_use = -1;
  30
  31         if (cached_use < 0)
  32                 cached_use = access("/sys/fs/smackfs/", F_OK) >= 0;
  33
  34         return cached_use;
  35 }
  36
  37 static const char* const smack_attr_table[_SMACK_ATTR_MAX] = {
  38         [SMACK_ATTR_ACCESS]     = "security.SMACK64",
  39         [SMACK_ATTR_EXEC]       = "security.SMACK64EXEC",
  40         [SMACK_ATTR_MMAP]       = "security.SMACK64MMAP",
  41         [SMACK_ATTR_TRANSMUTE]  = "security.SMACK64TRANSMUTE",
  42         [SMACK_ATTR_IPIN]       = "security.SMACK64IPIN",
  43         [SMACK_ATTR_IPOUT]      = "security.SMACK64IPOUT",
  44 };
  45
  46 DEFINE_STRING_TABLE_LOOKUP(smack_attr, SmackAttr);
  47
  48 int mac_smack_read(const char *path, SmackAttr attr, char **label) {
  49         assert(path);
  50         assert(attr >= 0 && attr < _SMACK_ATTR_MAX);
  51         assert(label);
  52
  53         if (!mac_smack_use())
  54                 return 0;
  55
  56         return getxattr_malloc(path, smack_attr_to_string(attr), label);
  57 }
  58
  59 int mac_smack_read_fd(int fd, SmackAttr attr, char **label) {
  60         assert(fd >= 0);
  61         assert(attr >= 0 && attr < _SMACK_ATTR_MAX);
  62         assert(label);
  63
  64         if (!mac_smack_use())
  65                 return 0;
  66
  67         return fgetxattr_malloc(fd, smack_attr_to_string(attr), label);
  68 }
  69
  70 int mac_smack_apply(const char *path, SmackAttr attr, const char *label) {
  71         int r;
  72
  73         assert(path);
  74         assert(attr >= 0 && attr < _SMACK_ATTR_MAX);
  75
  76         if (!mac_smack_use())
  77                 return 0;
  78
  79         if (label)
  80                 r = lsetxattr(path, smack_attr_to_string(attr), label, strlen(label), 0);
  81         else
  82                 r = lremovexattr(path, smack_attr_to_string(attr));
  83         if (r < 0)
  84                 return -errno;
  85
  86         return 0;
  87 }
  88
  89 int mac_smack_apply_fd(int fd, SmackAttr attr, const char *label) {
  90         int r;
  91
  92         assert(fd >= 0);
  93         assert(attr >= 0 && attr < _SMACK_ATTR_MAX);
  94
  95         if (!mac_smack_use())
  96                 return 0;
  97
  98         if (label)
  99                 r = setxattr(FORMAT_PROC_FD_PATH(fd), smack_attr_to_string(attr), label, strlen(label), 0);
 100         else
 101                 r = removexattr(FORMAT_PROC_FD_PATH(fd), smack_attr_to_string(attr));
 102         if (r < 0)
 103                 return -errno;
 104
 105         return 0;
 106 }
 107
 108 int mac_smack_apply_pid(pid_t pid, const char *label) {
 109         const char *p;
 110         int r;
 111
 112         assert(label);
 113
 114         if (!mac_smack_use())
 115                 return 0;
 116
 117         p = procfs_file_alloca(pid, "attr/current");
 118         r = write_string_file(p, label, WRITE_STRING_FILE_DISABLE_BUFFER);
 119         if (r < 0)
 120                 return r;
 121
 122         return r;
 123 }
 124
 125 static int smack_fix_fd(
 126                 int fd,
 127                 const char *label_path,
 128                 LabelFixFlags flags) {
 129
 130         const char *label;
 131         struct stat st;
 132         int r;
 133
 134         /* The caller should have done the sanity checks. */
 135         assert(fd >= 0);
 136         assert(label_path);
 137         assert(path_is_absolute(label_path));
 138
 139         /* Path must be in /dev. */
 140         if (!path_startswith(label_path, "/dev"))
 141                 return 0;
 142
 143         if (fstat(fd, &st) < 0)
 144                 return -errno;
 145
 146         /*
 147          * Label directories and character devices "*".
 148          * Label symlinks "_".
 149          * Don't change anything else.
 150          */
 151
 152         if (S_ISDIR(st.st_mode))
 153                 label = SMACK_STAR_LABEL;
 154         else if (S_ISLNK(st.st_mode))
 155                 label = SMACK_FLOOR_LABEL;
 156         else if (S_ISCHR(st.st_mode))
 157                 label = SMACK_STAR_LABEL;
 158         else
 159                 return 0;
 160
 161         if (setxattr(FORMAT_PROC_FD_PATH(fd), "security.SMACK64", label, strlen(label), 0) < 0) {
 162                 _cleanup_free_ char *old_label = NULL;
 163
 164                 r = -errno;
 165
 166                 /* If the FS doesn't support labels, then exit without warning */
 167                 if (ERRNO_IS_NOT_SUPPORTED(r))
 168                         return 0;
 169
 170                 /* It the FS is read-only and we were told to ignore failures caused by that, suppress error */
 171                 if (r == -EROFS && (flags & LABEL_IGNORE_EROFS))
 172                         return 0;
 173
 174                 /* If the old label is identical to the new one, suppress any kind of error */
 175                 if (lgetxattr_malloc(FORMAT_PROC_FD_PATH(fd), "security.SMACK64", &old_label) >= 0 &&
 176                     streq(old_label, label))
 177                         return 0;
 178
 179                 return log_debug_errno(r, "Unable to fix SMACK label of %s: %m", label_path);
 180         }
 181
 182         return 0;
 183 }
 184
 185 int mac_smack_fix_full(
 186                 int atfd,
 187                 const char *inode_path,
 188                 const char *label_path,
 189                 LabelFixFlags flags) {
 190
 191         _cleanup_close_ int opened_fd = -1;
 192         _cleanup_free_ char *p = NULL;
 193         int r, inode_fd;
 194
 195         assert(atfd >= 0 || atfd == AT_FDCWD);
 196         assert(atfd >= 0 || inode_path);
 197
 198         if (!mac_smack_use())
 199                 return 0;
 200
 201         if (inode_path) {
 202                 opened_fd = openat(atfd, inode_path, O_NOFOLLOW|O_CLOEXEC|O_PATH);
 203                 if (opened_fd < 0) {
 204                         if ((flags & LABEL_IGNORE_ENOENT) && errno == ENOENT)
 205                                 return 0;
 206
 207                         return -errno;
 208                 }
 209                 inode_fd = opened_fd;
 210         } else
 211                 inode_fd = atfd;
 212
 213         if (!label_path) {
 214                 if (path_is_absolute(inode_path))
 215                         label_path = inode_path;
 216                 else {
 217                         r = fd_get_path(inode_fd, &p);
 218                         if (r < 0)
 219                                 return r;
 220
 221                         label_path = p;
 222                 }
 223         }
 224
 225         return smack_fix_fd(inode_fd, label_path, flags);
 226 }
 227
 228 int mac_smack_copy(const char *dest, const char *src) {
 229         int r;
 230         _cleanup_free_ char *label = NULL;
 231
 232         assert(dest);
 233         assert(src);
 234
 235         r = mac_smack_read(src, SMACK_ATTR_ACCESS, &label);
 236         if (r < 0)
 237                 return r;
 238
 239         r = mac_smack_apply(dest, SMACK_ATTR_ACCESS, label);
 240         if (r < 0)
 241                 return r;
 242
 243         return r;
 244 }
 245
 246 #else
 247 bool mac_smack_use(void) {
 248         return false;
 249 }
 250
 251 int mac_smack_read(const char *path, SmackAttr attr, char **label) {
 252         return -EOPNOTSUPP;
 253 }
 254
 255 int mac_smack_read_fd(int fd, SmackAttr attr, char **label) {
 256         return -EOPNOTSUPP;
 257 }
 258
 259 int mac_smack_apply(const char *path, SmackAttr attr, const char *label) {
 260         return 0;
 261 }
 262
 263 int mac_smack_apply_fd(int fd, SmackAttr attr, const char *label) {
 264         return 0;
 265 }
 266
 267 int mac_smack_apply_pid(pid_t pid, const char *label) {
 268         return 0;
 269 }
 270
 271 int mac_smack_fix_full(int atfd, const char *inode_path, const char *label_path, LabelFixFlags flags) {
 272         return 0;
 273 }
 274
 275 int mac_smack_copy(const char *dest, const char *src) {
 276         return 0;
 277 }
 278 #endif
 279
 280 int rename_and_apply_smack_floor_label(const char *from, const char *to) {
 281
 282         if (rename(from, to) < 0)
 283                 return -errno;
 284
 285 #if HAVE_SMACK_RUN_LABEL
 286         return mac_smack_apply(to, SMACK_ATTR_ACCESS, SMACK_FLOOR_LABEL);
 287 #else
 288         return 0;
 289 #endif
 290 }