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shadow/btrfs-subvolumes.patch

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commit 52ea836ffbfa4d6797cf89d6ada58f76bee9cf6b
Author: Adam Majer <amajer@suse.de>
Date: Wed Jan 23 16:17:05 2019 +0100
Add autotools support for BtrFS option
Feature is enabled by default, if headers are available. It can be
turned off explictly.
commit 81ead2042afcdb8d423da855cf1528618a4e0c01
Author: Adam Majer <amajer@suse.de>
Date: Mon Jan 21 09:32:36 2019 +0100
Add support for btrfs subvolumes for user homes
new switch added to useradd command, --btrfs-subvolume-home. When
specified *and* the filesystem is detected as btrfs, it will create a
subvolume for user's home instead of a plain directory. This is done via
`btrfs subvolume` command. Specifying the new switch while trying to
create home on non-btrfs will result in an error.
userdel -r will handle and remove this subvolume transparently via
`btrfs subvolume` command. Previosuly this failed as you can't rmdir a
subvolume.
usermod, when moving user's home across devices, will detect if the home
is a subvolume and issue an error messages instead of copying it. Moving
user's home (as subvolume) on same btrfs works transparently.
--- a/configure.ac
+++ b/configure.ac
@@ -256,6 +256,9 @@ AC_ARG_WITH(audit,
AC_ARG_WITH(libpam,
[AC_HELP_STRING([--with-libpam], [use libpam for PAM support @<:@default=yes if found@:>@])],
[with_libpam=$withval], [with_libpam=maybe])
+AC_ARG_WITH(btrfs,
+ [AC_HELP_STRING([--with-btrfs], [add BtrFS support @<:@default=yes if found@:>@])],
+ [with_selinux=$withval], [with_selinux=maybe])
AC_ARG_WITH(selinux,
[AC_HELP_STRING([--with-selinux], [use SELinux support @<:@default=yes if found@:>@])],
[with_selinux=$withval], [with_selinux=maybe])
@@ -453,6 +456,20 @@ if test "$with_libcrack" = "yes"; then
AC_DEFINE(HAVE_LIBCRACK_PW, 1, [Defined if it includes *Pw functions.]))
fi
+if test "$with_btrfs" != "no"; then
+ AC_CHECK_HEADERS([sys/statfs.h linux/magic.h linux/btrfs_tree.h], \
+ [btrfs_headers="yes"], [btrfs_headers="no"])
+ if test "$btrfs_headers$with_btrfs" = "noyes" ; then
+ AC_MSG_ERROR([One of sys/statfs.h linux/magic.h linux/btrfs_tree.h is missing])
+ fi
+
+ if test "$btrfs_headers" = "yes" ; then
+ AC_DEFINE(WITH_BTRFS, 1, [Build shadow with BtrFS support])
+ with_btrfs="yes"
+ fi
+fi
+AM_CONDITIONAL(WITH_BTRFS, test x$with_btrfs = xyes)
+
AC_SUBST(LIBSELINUX)
AC_SUBST(LIBSEMANAGE)
if test "$with_selinux" != "no"; then
@@ -672,6 +689,7 @@ if test "$with_libpam" = "yes"; then
echo " suid account management tools: $enable_acct_tools_setuid"
fi
echo " SELinux support: $with_selinux"
+echo " BtrFS support: $with_btrfs"
echo " ACL support: $with_acl"
echo " Extended Attributes support: $with_attr"
echo " tcb support (incomplete): $with_tcb"
--- a/lib/prototypes.h
+++ b/lib/prototypes.h
@@ -72,6 +72,14 @@ extern int expire (const struct passwd *
/* isexpired.c */
extern int isexpired (const struct passwd *, /*@null@*/const struct spwd *);
+/* btrfs.c */
+#ifdef WITH_BTRFS
+extern int btrfs_create_subvolume(const char *path);
+extern int btrfs_remove_subvolume(const char *path);
+extern int btrfs_is_subvolume(const char *path);
+extern int is_btrfs(const char *path);
+#endif
+
/* basename() renamed to Basename() to avoid libc name space confusion */
/* basename.c */
extern /*@observer@*/const char *Basename (const char *str);
--- a/libmisc/Makefile.am
+++ b/libmisc/Makefile.am
@@ -72,3 +72,8 @@ libmisc_a_SOURCES = \
xgetspnam.c \
xmalloc.c \
yesno.c
+
+if WITH_BTRFS
+libmisc_a_SOURCES += btrfs.c
+endif
+
--- /dev/null
+++ b/libmisc/btrfs.c
@@ -0,0 +1,94 @@
+#include <linux/btrfs_tree.h>
+#include <linux/magic.h>
+#include <sys/statfs.h>
+
+#include "prototypes.h"
+
+
+static int run_btrfs_subvolume_cmd(const char *subcmd, const char *arg1, const char *arg2)
+{
+ int status = 0;
+ const char *cmd = "/sbin/btrfs";
+ const char *argv[] = {
+ strrchr(cmd, '/'),
+ "subvolume",
+ subcmd,
+ arg1,
+ arg2,
+ NULL
+ };
+
+ if (argv[0] == NULL)
+ argv[0] = cmd;
+ else
+ argv[0] = argv[0] + 1;
+
+ if (access(cmd, X_OK)) {
+ return 1;
+ }
+
+ if (run_command(cmd, argv, NULL, &status))
+ return -1;
+ return status;
+}
+
+
+int btrfs_create_subvolume(const char *path)
+{
+ return run_btrfs_subvolume_cmd("create", path, NULL);
+}
+
+
+int btrfs_remove_subvolume(const char *path)
+{
+ return run_btrfs_subvolume_cmd("delete", "-C", path);
+}
+
+
+/* Adapted from btrfsprogs */
+/*
+ * This intentionally duplicates btrfs_util_is_subvolume_fd() instead of opening
+ * a file descriptor and calling it, because fstat() and fstatfs() don't accept
+ * file descriptors opened with O_PATH on old kernels (before v3.6 and before
+ * v3.12, respectively), but stat() and statfs() can be called on a path that
+ * the user doesn't have read or write permissions to.
+ *
+ * returns:
+ * 1 - btrfs subvolume
+ * 0 - not btrfs subvolume
+ * -1 - error
+ */
+int btrfs_is_subvolume(const char *path)
+{
+ struct stat st;
+ int ret;
+
+ ret = is_btrfs(path);
+ if (ret <= 0)
+ return ret;
+
+ ret = stat(path, &st);
+ if (ret == -1)
+ return -1;
+
+ if (st.st_ino != BTRFS_FIRST_FREE_OBJECTID || !S_ISDIR(st.st_mode)) {
+ return 0;
+ }
+
+ return 1;
+}
+
+
+/* Adapted from btrfsprogs */
+int is_btrfs(const char *path)
+{
+ struct statfs sfs;
+ int ret;
+
+ ret = statfs(path, &sfs);
+ if (ret == -1)
+ return -1;
+
+ return sfs.f_type == BTRFS_SUPER_MAGIC;
+}
+
--- a/src/useradd.c
+++ b/src/useradd.c
@@ -164,6 +164,7 @@ static bool
oflg = false, /* permit non-unique user ID to be specified with -u */
rflg = false, /* create a system account */
sflg = false, /* shell program for new account */
+ subvolflg = false, /* create subvolume home on BTRFS */
uflg = false, /* specify user ID for new account */
Uflg = false; /* create a group having the same name as the user */
@@ -805,6 +806,9 @@ static void usage (int status)
Prog, Prog, Prog);
(void) fputs (_(" -b, --base-dir BASE_DIR base directory for the home directory of the\n"
" new account\n"), usageout);
+#ifdef WITH_BTRFS
+ (void) fputs (_(" --btrfs-subvolume-home use BTRFS subvolume for home directory\n"), usageout);
+#endif
(void) fputs (_(" -c, --comment COMMENT GECOS field of the new account\n"), usageout);
(void) fputs (_(" -d, --home-dir HOME_DIR home directory of the new account\n"), usageout);
(void) fputs (_(" -D, --defaults print or change default useradd configuration\n"), usageout);
@@ -1085,6 +1089,9 @@ static void process_flags (int argc, cha
int c;
static struct option long_options[] = {
{"base-dir", required_argument, NULL, 'b'},
+#ifdef WITH_BTRFS
+ {"btrfs-subvolume-home", no_argument, NULL, 200},
+#endif
{"comment", required_argument, NULL, 'c'},
{"home-dir", required_argument, NULL, 'd'},
{"defaults", no_argument, NULL, 'D'},
@@ -1131,6 +1138,9 @@ static void process_flags (int argc, cha
def_home = optarg;
bflg = true;
break;
+ case 200:
+ subvolflg = true;
+ break;
case 'c':
if (!VALID (optarg)) {
fprintf (stderr,
@@ -2049,6 +2059,37 @@ static void create_home (void)
strcat (path, "/");
strcat (path, cp);
if (access (path, F_OK) != 0) {
+ /* Check if parent directory is BTRFS, fail if requesting
+ subvolume but no BTRFS. The paths cound be different by the
+ trailing slash
+ */
+#if WITH_BTRFS
+ if (subvolflg && (strlen(prefix_user_home) - (int)strlen(path)) <= 1) {
+ char *btrfs_check = strdup(path);
+
+ if (!btrfs_check) {
+ fprintf (stderr,
+ _("%s: error while duplicating string in BTRFS check %s\n"),
+ Prog, path);
+ fail_exit (E_HOMEDIR);
+ }
+ btrfs_check[strlen(path) - strlen(cp) - 1] = '\0';
+ if (is_btrfs(btrfs_check) <= 0) {
+ fprintf (stderr,
+ _("%s: home directory \"%s\" must be mounted on BTRFS\n"),
+ Prog, path);
+ fail_exit (E_HOMEDIR);
+ }
+ // make subvolume to mount for user instead of directory
+ if (btrfs_create_subvolume(path)) {
+ fprintf (stderr,
+ _("%s: failed to create BTRFS subvolume: %s\n"),
+ Prog, path);
+ fail_exit (E_HOMEDIR);
+ }
+ }
+ else
+#endif
if (mkdir (path, 0) != 0) {
fprintf (stderr,
_("%s: cannot create directory %s\n"),
--- a/src/userdel.c
+++ b/src/userdel.c
@@ -1273,6 +1273,23 @@ int main (int argc, char **argv)
#endif /* EXTRA_CHECK_HOME_DIR */
if (rflg) {
+#ifdef WITH_BTRFS
+ int is_subvolume = btrfs_is_subvolume (user_home);
+ if (is_subvolume < 0) {
+ errors++;
+ /* continue */
+ }
+ else if (is_subvolume > 0) {
+ if (btrfs_remove_subvolume (user_home)) {
+ fprintf (stderr,
+ _("%s: error removing subvolume %s\n"),
+ Prog, user_home);
+ errors++;
+ /* continue */
+ }
+ }
+ else
+#endif
if (remove_tree (user_home, true) != 0) {
fprintf (stderr,
_("%s: error removing directory %s\n"),
--- a/src/usermod.c
+++ b/src/usermod.c
@@ -1818,6 +1818,15 @@ static void move_home (void)
return;
} else {
if (EXDEV == errno) {
+#ifdef WITH_BTRFS
+ if (btrfs_is_subvolume (prefix_user_home) > 0) {
+ fprintf (stderr,
+ _("%s: error: cannot move subvolume from %s to %s - different device\n"),
+ Prog, prefix_user_home, prefix_user_newhome);
+ fail_exit (E_HOMEDIR);
+ }
+#endif
+
if (copy_tree (prefix_user_home, prefix_user_newhome, true,
true,
user_id,
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