From 9999e48639b3cecb08ffb37358bcba3b48161b29 Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Fri, 10 May 2024 08:50:17 +0000
Subject: [PATCH] add ax88772_rst
---
kernel/fs/attr.c | 90 ++++++++++++++++++++++++++++++++++++++++----
1 files changed, 81 insertions(+), 9 deletions(-)
diff --git a/kernel/fs/attr.c b/kernel/fs/attr.c
index 22aa50c..375692e 100644
--- a/kernel/fs/attr.c
+++ b/kernel/fs/attr.c
@@ -18,6 +18,65 @@
#include <linux/evm.h>
#include <linux/ima.h>
+#include "internal.h"
+
+/**
+ * setattr_should_drop_sgid - determine whether the setgid bit needs to be
+ * removed
+ * @inode: inode to check
+ *
+ * This function determines whether the setgid bit needs to be removed.
+ * We retain backwards compatibility and require setgid bit to be removed
+ * unconditionally if S_IXGRP is set. Otherwise we have the exact same
+ * requirements as setattr_prepare() and setattr_copy().
+ *
+ * Return: ATTR_KILL_SGID if setgid bit needs to be removed, 0 otherwise.
+ */
+int setattr_should_drop_sgid(const struct inode *inode)
+{
+ umode_t mode = inode->i_mode;
+
+ if (!(mode & S_ISGID))
+ return 0;
+ if (mode & S_IXGRP)
+ return ATTR_KILL_SGID;
+ if (!in_group_or_capable(inode, inode->i_gid))
+ return ATTR_KILL_SGID;
+ return 0;
+}
+
+/**
+ * setattr_should_drop_suidgid - determine whether the set{g,u}id bit needs to
+ * be dropped
+ * @inode: inode to check
+ *
+ * This function determines whether the set{g,u}id bits need to be removed.
+ * If the setuid bit needs to be removed ATTR_KILL_SUID is returned. If the
+ * setgid bit needs to be removed ATTR_KILL_SGID is returned. If both
+ * set{g,u}id bits need to be removed the corresponding mask of both flags is
+ * returned.
+ *
+ * Return: A mask of ATTR_KILL_S{G,U}ID indicating which - if any - setid bits
+ * to remove, 0 otherwise.
+ */
+int setattr_should_drop_suidgid(struct inode *inode)
+{
+ umode_t mode = inode->i_mode;
+ int kill = 0;
+
+ /* suid always must be killed */
+ if (unlikely(mode & S_ISUID))
+ kill = ATTR_KILL_SUID;
+
+ kill |= setattr_should_drop_sgid(inode);
+
+ if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode)))
+ return kill;
+
+ return 0;
+}
+EXPORT_SYMBOL(setattr_should_drop_suidgid);
+
static bool chown_ok(const struct inode *inode, kuid_t uid)
{
if (uid_eq(current_fsuid(), inode->i_uid) &&
@@ -90,9 +149,8 @@
if (!inode_owner_or_capable(inode))
return -EPERM;
/* Also check the setgid bit! */
- if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
- inode->i_gid) &&
- !capable_wrt_inode_uidgid(inode, CAP_FSETID))
+ if (!in_group_or_capable(inode, (ia_valid & ATTR_GID) ?
+ attr->ia_gid : inode->i_gid))
attr->ia_mode &= ~S_ISGID;
}
@@ -193,9 +251,7 @@
inode->i_ctime = attr->ia_ctime;
if (ia_valid & ATTR_MODE) {
umode_t mode = attr->ia_mode;
-
- if (!in_group_p(inode->i_gid) &&
- !capable_wrt_inode_uidgid(inode, CAP_FSETID))
+ if (!in_group_or_capable(inode, inode->i_gid))
mode &= ~S_ISGID;
inode->i_mode = mode;
}
@@ -253,9 +309,25 @@
}
if ((ia_valid & ATTR_MODE)) {
- umode_t amode = attr->ia_mode;
+ /*
+ * Don't allow changing the mode of symlinks:
+ *
+ * (1) The vfs doesn't take the mode of symlinks into account
+ * during permission checking.
+ * (2) This has never worked correctly. Most major filesystems
+ * did return EOPNOTSUPP due to interactions with POSIX ACLs
+ * but did still updated the mode of the symlink.
+ * This inconsistency led system call wrapper providers such
+ * as libc to block changing the mode of symlinks with
+ * EOPNOTSUPP already.
+ * (3) To even do this in the first place one would have to use
+ * specific file descriptors and quite some effort.
+ */
+ if (S_ISLNK(inode->i_mode))
+ return -EOPNOTSUPP;
+
/* Flag setting protected by i_mutex */
- if (is_sxid(amode))
+ if (is_sxid(attr->ia_mode))
inode->i_flags &= ~S_NOSEC;
}
@@ -297,7 +369,7 @@
}
}
if (ia_valid & ATTR_KILL_SGID) {
- if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
+ if (mode & S_ISGID) {
if (!(ia_valid & ATTR_MODE)) {
ia_valid = attr->ia_valid |= ATTR_MODE;
attr->ia_mode = inode->i_mode;
--
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