From ea08eeccae9297f7aabd2ef7f0c2517ac4549acc Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:18:26 +0000
Subject: [PATCH] write in 30M
---
kernel/fs/inode.c | 124 +++++++++++++++++++++++++++++-----------
1 files changed, 89 insertions(+), 35 deletions(-)
diff --git a/kernel/fs/inode.c b/kernel/fs/inode.c
index 996bd56..4102cfe 100644
--- a/kernel/fs/inode.c
+++ b/kernel/fs/inode.c
@@ -158,7 +158,7 @@
inode->i_bdev = NULL;
inode->i_cdev = NULL;
inode->i_link = NULL;
- inode->__i_dir_seq = 0;
+ inode->i_dir_seq = 0;
inode->i_rdev = 0;
inode->dirtied_when = 0;
@@ -1016,6 +1016,48 @@
EXPORT_SYMBOL(discard_new_inode);
/**
+ * lock_two_inodes - lock two inodes (may be regular files but also dirs)
+ *
+ * Lock any non-NULL argument. The caller must make sure that if he is passing
+ * in two directories, one is not ancestor of the other. Zero, one or two
+ * objects may be locked by this function.
+ *
+ * @inode1: first inode to lock
+ * @inode2: second inode to lock
+ * @subclass1: inode lock subclass for the first lock obtained
+ * @subclass2: inode lock subclass for the second lock obtained
+ */
+void lock_two_inodes(struct inode *inode1, struct inode *inode2,
+ unsigned subclass1, unsigned subclass2)
+{
+ if (!inode1 || !inode2) {
+ /*
+ * Make sure @subclass1 will be used for the acquired lock.
+ * This is not strictly necessary (no current caller cares) but
+ * let's keep things consistent.
+ */
+ if (!inode1)
+ swap(inode1, inode2);
+ goto lock;
+ }
+
+ /*
+ * If one object is directory and the other is not, we must make sure
+ * to lock directory first as the other object may be its child.
+ */
+ if (S_ISDIR(inode2->i_mode) == S_ISDIR(inode1->i_mode)) {
+ if (inode1 > inode2)
+ swap(inode1, inode2);
+ } else if (!S_ISDIR(inode1->i_mode))
+ swap(inode1, inode2);
+lock:
+ if (inode1)
+ inode_lock_nested(inode1, subclass1);
+ if (inode2 && inode2 != inode1)
+ inode_lock_nested(inode2, subclass2);
+}
+
+/**
* lock_two_nondirectories - take two i_mutexes on non-directory objects
*
* Lock any non-NULL argument that is not a directory.
@@ -1855,35 +1897,6 @@
EXPORT_SYMBOL_NS(touch_atime, ANDROID_GKI_VFS_EXPORT_ONLY);
/*
- * The logic we want is
- *
- * if suid or (sgid and xgrp)
- * remove privs
- */
-int should_remove_suid(struct dentry *dentry)
-{
- umode_t mode = d_inode(dentry)->i_mode;
- int kill = 0;
-
- /* suid always must be killed */
- if (unlikely(mode & S_ISUID))
- kill = ATTR_KILL_SUID;
-
- /*
- * sgid without any exec bits is just a mandatory locking mark; leave
- * it alone. If some exec bits are set, it's a real sgid; kill it.
- */
- if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
- kill |= ATTR_KILL_SGID;
-
- if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode)))
- return kill;
-
- return 0;
-}
-EXPORT_SYMBOL(should_remove_suid);
-
-/*
* Return mask of changes for notify_change() that need to be done as a
* response to write or truncate. Return 0 if nothing has to be changed.
* Negative value on error (change should be denied).
@@ -1897,7 +1910,7 @@
if (IS_NOSEC(inode))
return 0;
- mask = should_remove_suid(dentry);
+ mask = setattr_should_drop_suidgid(inode);
ret = security_inode_need_killpriv(dentry);
if (ret < 0)
return ret;
@@ -2147,10 +2160,6 @@
/* Directories are special, and always inherit S_ISGID */
if (S_ISDIR(mode))
mode |= S_ISGID;
- else if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP) &&
- !in_group_p(inode->i_gid) &&
- !capable_wrt_inode_uidgid(dir, CAP_FSETID))
- mode &= ~S_ISGID;
} else
inode->i_gid = current_fsgid();
inode->i_mode = mode;
@@ -2382,3 +2391,48 @@
return 0;
}
EXPORT_SYMBOL(vfs_ioc_fssetxattr_check);
+
+/**
+ * in_group_or_capable - check whether caller is CAP_FSETID privileged
+ * @inode: inode to check
+ * @gid: the new/current gid of @inode
+ *
+ * Check wether @gid is in the caller's group list or if the caller is
+ * privileged with CAP_FSETID over @inode. This can be used to determine
+ * whether the setgid bit can be kept or must be dropped.
+ *
+ * Return: true if the caller is sufficiently privileged, false if not.
+ */
+bool in_group_or_capable(const struct inode *inode, kgid_t gid)
+{
+ if (in_group_p(gid))
+ return true;
+ if (capable_wrt_inode_uidgid(inode, CAP_FSETID))
+ return true;
+ return false;
+}
+
+/**
+ * mode_strip_sgid - handle the sgid bit for non-directories
+ * @dir: parent directory inode
+ * @mode: mode of the file to be created in @dir
+ *
+ * If the @mode of the new file has both the S_ISGID and S_IXGRP bit
+ * raised and @dir has the S_ISGID bit raised ensure that the caller is
+ * either in the group of the parent directory or they have CAP_FSETID
+ * in their user namespace and are privileged over the parent directory.
+ * In all other cases, strip the S_ISGID bit from @mode.
+ *
+ * Return: the new mode to use for the file
+ */
+umode_t mode_strip_sgid(const struct inode *dir, umode_t mode)
+{
+ if ((mode & (S_ISGID | S_IXGRP)) != (S_ISGID | S_IXGRP))
+ return mode;
+ if (S_ISDIR(mode) || !dir || !(dir->i_mode & S_ISGID))
+ return mode;
+ if (in_group_or_capable(dir, dir->i_gid))
+ return mode;
+ return mode & ~S_ISGID;
+}
+EXPORT_SYMBOL(mode_strip_sgid);
--
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