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mount-util: beef up bind_remount_recursive() to be able to toggle more than MS_RDONLY

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The function is otherwise generic enough to toggle other bind mount
flags beyond MS_RDONLY (for example: MS_NOSUID or MS_NODEV), hence let's
beef it up slightly to support that too.
This commit is contained in:
Lennart Poettering
2019-03-25 19:33:55 +01:00
parent f0a95a2c6d
commit 64e82c1976
6 changed files with 21 additions and 16 deletions
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src/shared/mount-util.c
+13 -8
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@@ -107,10 +107,15 @@ static int get_mount_flags(const char *path, unsigned long *flags) {
return 0;
}
/* Use this function only if do you have direct access to /proc/self/mountinfo
* and need the caller to open it for you. This is the case when /proc is
* masked or not mounted. Otherwise, use bind_remount_recursive. */
int bind_remount_recursive_with_mountinfo(const char *prefix, bool ro, char **blacklist, FILE *proc_self_mountinfo) {
/* Use this function only if do you have direct access to /proc/self/mountinfo and need the caller to open it
* for you. This is the case when /proc is masked or not mounted. Otherwise, use bind_remount_recursive. */
int bind_remount_recursive_with_mountinfo(
const char *prefix,
unsigned long new_flags,
unsigned long flags_mask,
char **blacklist,
FILE *proc_self_mountinfo) {
_cleanup_set_free_free_ Set *done = NULL;
_cleanup_free_ char *cleaned = NULL;
int r;
@@ -245,7 +250,7 @@ int bind_remount_recursive_with_mountinfo(const char *prefix, bool ro, char **bl
(void) get_mount_flags(cleaned, &orig_flags);
orig_flags &= ~MS_RDONLY;
if (mount(NULL, cleaned, NULL, orig_flags|MS_BIND|MS_REMOUNT|(ro ? MS_RDONLY : 0), NULL) < 0)
if (mount(NULL, cleaned, NULL, (orig_flags & ~flags_mask)|MS_BIND|MS_REMOUNT|new_flags, NULL) < 0)
return -errno;
log_debug("Made top-level directory %s a mount point.", prefix);
@@ -287,7 +292,7 @@ int bind_remount_recursive_with_mountinfo(const char *prefix, bool ro, char **bl
(void) get_mount_flags(x, &orig_flags);
orig_flags &= ~MS_RDONLY;
if (mount(NULL, x, NULL, orig_flags|MS_BIND|MS_REMOUNT|(ro ? MS_RDONLY : 0), NULL) < 0)
if (mount(NULL, x, NULL, (orig_flags & ~flags_mask)|MS_BIND|MS_REMOUNT|new_flags, NULL) < 0)
return -errno;
log_debug("Remounted %s read-only.", x);
@@ -295,7 +300,7 @@ int bind_remount_recursive_with_mountinfo(const char *prefix, bool ro, char **bl
}
}
int bind_remount_recursive(const char *prefix, bool ro, char **blacklist) {
int bind_remount_recursive(const char *prefix, unsigned long new_flags, unsigned long flags_mask, char **blacklist) {
_cleanup_fclose_ FILE *proc_self_mountinfo = NULL;
proc_self_mountinfo = fopen("/proc/self/mountinfo", "re");
@@ -304,7 +309,7 @@ int bind_remount_recursive(const char *prefix, bool ro, char **blacklist) {
(void) __fsetlocking(proc_self_mountinfo, FSETLOCKING_BYCALLER);
return bind_remount_recursive_with_mountinfo(prefix, ro, blacklist, proc_self_mountinfo);
return bind_remount_recursive_with_mountinfo(prefix, new_flags, flags_mask, blacklist, proc_self_mountinfo);
}
int mount_move_root(const char *path) {