From: Karel Zak <kzak@redhat.com>
Date: Mon, 26 Sep 2022 07:45:04 +0000 (+0200)
Subject: libmount: (mount) support propagation by new kernel API
X-Git-Tag: v2.39-rc1~252
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=6753e6f6912658e836966a6316df956e1af5fcae;p=thirdparty%2Futil-linux.git

libmount: (mount) support propagation by new kernel API

Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/libmount/src/context.c b/libmount/src/context.c
index 1cf8321c07..e602ce54bc 100644
--- a/libmount/src/context.c
+++ b/libmount/src/context.c
@@ -2456,12 +2456,11 @@ int mnt_context_propagation_only(struct libmnt_context *cxt)
 
 	if (cxt->action != MNT_ACT_MOUNT)
 		return 0;
-
 	if (cxt->mountdata || cxt->fs == NULL)
 		return 0;
-
-	if ((cxt->fs->fstype && strcmp(cxt->fs->fstype, "none") != 0) ||
-	    (cxt->fs->source && strcmp(cxt->fs->source, "none") == 0))
+	if (cxt->fs->fstype && strcmp(cxt->fs->fstype, "none") != 0)
+		return 0;
+	if (cxt->fs->source && strcmp(cxt->fs->source, "none") != 0)
 		return 0;
 
 	ls = mnt_context_get_optlist(cxt);
diff --git a/libmount/src/hook_mount.c b/libmount/src/hook_mount.c
index abfd00ebf7..4cc44b8c19 100644
--- a/libmount/src/hook_mount.c
+++ b/libmount/src/hook_mount.c
@@ -140,6 +140,8 @@ static int hook_set_vfsflags(struct libmnt_context *cxt,
 	uint64_t set = 0, clr = 0;
 	int rc;
 
+	DBG(HOOK, ul_debugobj(hs, "setting VFS flags"));
+
 	api = get_sysapi(cxt, hs);
 	assert(api);
 	assert(api->fd_tree >= 0);
@@ -166,10 +168,55 @@ static int hook_set_vfsflags(struct libmnt_context *cxt,
 	return rc == 0 ? 0 : -errno;
 }
 
-static int hook_set_propagation(struct libmnt_context *cxt __attribute__((__unused__)),
-			const struct libmnt_hookset *hs __attribute__((__unused__)),
+static int hook_set_propagation(struct libmnt_context *cxt,
+			const struct libmnt_hookset *hs,
 			void *data __attribute__((__unused__)))
 {
+	struct libmnt_sysapi *api;
+	struct libmnt_optlist *ol;
+	struct libmnt_iter itr;
+	struct libmnt_opt *opt;
+	int rc = 0;
+
+	DBG(HOOK, ul_debugobj(hs, "setting propagation"));
+
+	ol = mnt_context_get_optlist(cxt);
+	if (!ol)
+		return -ENOMEM;
+
+	api = get_sysapi(cxt, hs);
+	assert(api);
+	assert(api->fd_tree >= 0);
+
+	mnt_reset_iter(&itr, MNT_ITER_FORWARD);
+
+	while (mnt_optlist_next_opt(ol, &itr, &opt) == 0) {
+		const struct libmnt_optmap *map = mnt_opt_get_map(opt);
+		const struct libmnt_optmap *ent = mnt_opt_get_mapent(opt);
+		struct mount_attr attr = { .attr_clr = 0 };
+		unsigned int flgs = AT_EMPTY_PATH;
+
+		if (cxt->map_linux != map)
+			continue;
+		if (mnt_opt_is_external(opt))
+			continue;
+		if (!ent || !ent->id || !(ent->id & MS_PROPAGATION))
+			continue;
+
+		attr.propagation = ent->id & MS_PROPAGATION;
+		if (ent->id & MS_REC)
+			flgs |= AT_RECURSIVE;
+
+		DBG(HOOK, ul_debugobj(hs,
+			"mount_setattr(propagation=0x%08" PRIx64")",
+			(uint64_t) attr.propagation));
+
+		rc = mount_setattr(api->fd_tree, "", flgs, &attr, sizeof(attr));
+		set_syscall_status(cxt, "move_setattr", rc == 0);
+		if (rc != 0)
+			return rc;
+	}
+
 	return 0;
 }
 
@@ -210,9 +257,12 @@ static int init_sysapi(struct libmnt_context *cxt,
 	assert(cxt);
 	assert(hs);
 
+	DBG(HOOK, ul_debugobj(hs, "initialize API fds"));
+
 	/* A) tree based operation -- the tree is mount source */
 	if ((flags & MS_BIND)
 	    || (flags & MS_MOVE)) {
+		DBG(HOOK, ul_debugobj(hs, " BIND/MOVE"));
 		path = mnt_fs_get_srcpath(cxt->fs);
 		if (!path)
 			return -EINVAL;
@@ -220,6 +270,7 @@ static int init_sysapi(struct libmnt_context *cxt,
 	/* B) tree based operation -- the tree is mount point */
 	} else if ((flags & MS_REMOUNT)
 	    || mnt_context_propagation_only(cxt)) {
+		DBG(HOOK, ul_debugobj(hs, " REMOUNT/propagation"));
 		path = mnt_fs_get_target(cxt->fs);
 		if (!path)
 			return -EINVAL;
@@ -238,7 +289,7 @@ static int init_sysapi(struct libmnt_context *cxt,
 		if (flags & MS_BIND)
 			oflg |= OPEN_TREE_CLONE;
 
-		DBG(HOOK, ul_debugobj(hs, "open_tree(%s)", path));
+		DBG(HOOK, ul_debugobj(hs, "open_tree(path=%s, flgs=0x%08lx)", path, oflg));
 		if (mnt_context_is_fake(cxt))
 			goto fake;
 
@@ -249,6 +300,7 @@ static int init_sysapi(struct libmnt_context *cxt,
 
 	/* C) FS based operation */
 	} else {
+		DBG(HOOK, ul_debugobj(hs, " new FS"));
 		const char *type = mnt_fs_get_fstype(cxt->fs);
 
 		if (!type)
@@ -345,7 +397,7 @@ static int hook_prepare(struct libmnt_context *cxt,
 					hook_attach_target);
 
 	/* set propagation (has to be attached to VFS) */
-	if (!rc && mnt_optlist_get_propagation(ol) != 0)
+	if (!rc && mnt_optlist_get_propagation(ol))
 		rc = mnt_context_append_hook(cxt, hs, MNT_STAGE_MOUNT_POST, NULL,
 					hook_set_propagation);
 
diff --git a/libmount/src/mountP.h b/libmount/src/mountP.h
index 8304d3af0e..3345a14dec 100644
--- a/libmount/src/mountP.h
+++ b/libmount/src/mountP.h
@@ -557,7 +557,7 @@ extern int mnt_opt_set_external(struct libmnt_opt *opt, int enable);
 extern int mnt_opt_set_value(struct libmnt_opt *opt, const char *str);
 extern int mnt_opt_set_u64value(struct libmnt_opt *opt, uint64_t num);
 extern int mnt_opt_set_quoted_value(struct libmnt_opt *opt, const char *str);
-
+extern int mnt_opt_is_external(struct libmnt_opt *opt);
 
 /* fs.c */
 extern int mnt_fs_follow_optlist(struct libmnt_fs *fs, struct libmnt_optlist *ol);
diff --git a/libmount/src/optlist.c b/libmount/src/optlist.c
index 939473dc56..dfef48fd08 100644
--- a/libmount/src/optlist.c
+++ b/libmount/src/optlist.c
@@ -747,28 +747,27 @@ int mnt_optlist_get_flags(struct libmnt_optlist *ls, unsigned long *flags,
 }
 
 #ifdef UL_HAVE_MOUNT_API
-static inline uint64_t flags_to_attrs(unsigned long flags)
+static inline uint64_t flag_to_attr(unsigned long flag)
 {
-	uint64_t attrs = 0;
-
-	if (flags & MS_RDONLY)
-		attrs |= MOUNT_ATTR_RDONLY;
-	if (flags & MS_NOSUID)
-		attrs |= MOUNT_ATTR_NOSUID;
-	if (flags & MS_NOEXEC)
-		attrs |= MOUNT_ATTR_NOEXEC;
-	if (flags & MS_NODIRATIME)
-		attrs |= MOUNT_ATTR_NODIRATIME;
-	if (flags & MS_RELATIME)
-		attrs |= MOUNT_ATTR_RELATIME;
-	if (flags & MS_NOATIME)
-		attrs |= MOUNT_ATTR_NOATIME;
-	if (flags & MS_STRICTATIME)
-		attrs |= MOUNT_ATTR_STRICTATIME;
-	if (flags & MS_NOSYMFOLLOW)
-		attrs |= MOUNT_ATTR_NOSYMFOLLOW;
-
-	return attrs;
+	switch (flag) {
+	case MS_RDONLY:
+		return MOUNT_ATTR_RDONLY;
+	case MS_NOSUID:
+		return MOUNT_ATTR_NOSUID;
+	case MS_NOEXEC:
+		return MOUNT_ATTR_NOEXEC;
+	case MS_NODIRATIME:
+		return MOUNT_ATTR_NODIRATIME;
+	case MS_RELATIME:
+		return MOUNT_ATTR_RELATIME;
+	case MS_NOATIME:
+		return MOUNT_ATTR_NOATIME;
+	case MS_STRICTATIME:
+		return MOUNT_ATTR_STRICTATIME;
+	case MS_NOSYMFOLLOW:
+		return MOUNT_ATTR_NOSYMFOLLOW;
+	}
+	return 0;
 }
 #endif
 
@@ -785,24 +784,30 @@ int mnt_optlist_get_attrs(struct libmnt_optlist *ls, uint64_t *set, uint64_t *cl
 	if (!ls || !ls->linux_map || !set || !clr)
 		return -EINVAL;
 
+	*set = 0, *clr = 0;
 	mnt_reset_iter(&itr, MNT_ITER_FORWARD);
 
 	while (mnt_optlist_next_opt(ls, &itr, &opt) == 0) {
+		uint64_t x;
+
 		if (ls->linux_map != opt->map)
 			continue;
 		if (!opt->ent || !opt->ent->id)
 			continue;
 		if (!is_wanted_opt(opt, ls->linux_map, MNT_OL_FLTR_DFLT))
 			continue;
+		x = flag_to_attr( opt->ent->id );
+		if (!x)
+			continue;
 
 		if (opt->ent->mask & MNT_INVERT)
-			*clr |= flags_to_attrs( opt->ent->id );
+			*clr |= x;
 		else
-			*set |= flags_to_attrs( opt->ent->id );
+			*set |= x;
 	}
 
 	DBG(OPTLIST, ul_debugobj(ls, "return attrs set=0x%08" PRIx64
-				      ", clr=0x08%" PRIx64, *set, *clr));
+				      ", clr=0x%08" PRIx64, *set, *clr));
 	return 0;
 
 #endif
@@ -922,7 +927,7 @@ int mnt_optlist_is_propagation_only(struct libmnt_optlist *ls)
 		return 0;
 
 	rest = flags & ~MS_PROPAGATION;
-	return (rest == 0 || rest == MS_SILENT);
+	return (rest == 0 || (rest & (MS_SILENT | MS_REC)));
 }
 
 int mnt_optlist_is_remount(struct libmnt_optlist *ls)
@@ -1032,6 +1037,10 @@ int mnt_opt_set_external(struct libmnt_opt *opt, int enable)
 	return 0;
 }
 
+int mnt_opt_is_external(struct libmnt_opt *opt)
+{
+	return opt && opt->external ? 1 : 0;
+}
 
 
 #ifdef TEST_PROGRAM