Revert "kernel: Only expose su when daemon is running"lineage-19.1

This patch is no longer necessary because we no longer ship
su add-ons, which is this patch initially designed for. Now
it causes another issue which breaks custom root solution
such as Magisk, as Magisk switches worker tmpfs dir to RO
instead of RW for safety reasons and happens to satisfy
MS_RDONLY check for su file, resulting in su file totally
inaccessible.

This reverts commit 08ff8a2e58eb226015fa68d577121137a7e0953f.

Change-Id: If25a9ef7e64c79412948f4619e08faaedb18aa13

10 files changed, 0 insertions, 85 deletions

diff --git a/fs/exec.c b/fs/exec.c
index ebf8c18f6d56..341b872d758f 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1640,11 +1640,6 @@ static int do_execveat_common(int fd, struct filename *filename,
 	if (retval < 0)
 		goto out;
 
-	if (d_is_su(file->f_path.dentry) && capable(CAP_SYS_ADMIN)) {
-		current->flags |= PF_SU;
-		su_exec();
-	}
-
 	/* execve succeeded */
 	current->fs->in_exec = 0;
 	current->in_execve = 0;
diff --git a/fs/namei.c b/fs/namei.c
index e1d54d342ad5..8f350e39be96 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2292,16 +2292,6 @@ static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path
 			err = -ENOTDIR;
 
 	if (!err) {
-		struct super_block *sb = nd->inode->i_sb;
-		if (sb->s_flags & MS_RDONLY) {
-			if (d_is_su(nd->path.dentry) && !su_visible()) {
-				path_put(&nd->path);
-				err = -ENOENT;
-			}
-		}
-	}
-
-	if (!err) {
 		*path = nd->path;
 		nd->path.mnt = NULL;
 		nd->path.dentry = NULL;
diff --git a/fs/readdir.c b/fs/readdir.c
index 27807505fc4a..3494d7a8ff65 100644
--- a/fs/readdir.c
+++ b/fs/readdir.c
@@ -39,7 +39,6 @@ int iterate_dir(struct file *file, struct dir_context *ctx)
 	res = -ENOENT;
 	if (!IS_DEADDIR(inode)) {
 		ctx->pos = file->f_pos;
-		ctx->romnt = (inode->i_sb->s_flags & MS_RDONLY);
 		res = file->f_op->iterate(file, ctx);
 		file->f_pos = ctx->pos;
 		fsnotify_access(file);
@@ -51,14 +50,6 @@ out:
 }
 EXPORT_SYMBOL(iterate_dir);
 
-static bool hide_name(const char *name, int namlen)
-{
-	if (namlen == 2 && !memcmp(name, "su", 2))
-		if (!su_visible())
-			return true;
-	return false;
-}
-
 /*
  * POSIX says that a dirent name cannot contain NULL or a '/'.
  *
@@ -132,8 +123,6 @@ static int fillonedir(struct dir_context *ctx, const char *name, int namlen,
 		buf->result = -EOVERFLOW;
 		return -EOVERFLOW;
 	}
-	if (hide_name(name, namlen) && buf->ctx.romnt)
-		return 0;
 	buf->result++;
 	dirent = buf->dirent;
 	if (!access_ok(VERIFY_WRITE, dirent,
@@ -215,8 +204,6 @@ static int filldir(struct dir_context *ctx, const char *name, int namlen,
 		buf->error = -EOVERFLOW;
 		return -EOVERFLOW;
 	}
-	if (hide_name(name, namlen) && buf->ctx.romnt)
-		return 0;
 	dirent = buf->previous;
 	if (dirent) {
 		if (__put_user(offset, &dirent->d_off))
@@ -299,8 +286,6 @@ static int filldir64(struct dir_context *ctx, const char *name, int namlen,
 	buf->error = -EINVAL;	/* only used if we fail.. */
 	if (reclen > buf->count)
 		return -EINVAL;
-	if (hide_name(name, namlen) && buf->ctx.romnt)
-		return 0;
 	dirent = buf->previous;
 	if (dirent) {
 		if (__put_user(offset, &dirent->d_off))
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index d57e8a6c2f2c..c066f6b56e58 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -522,12 +522,6 @@ static inline bool d_is_fallthru(const struct dentry *dentry)
 	return dentry->d_flags & DCACHE_FALLTHRU;
 }
 
-static inline bool d_is_su(const struct dentry *dentry)
-{
-	return dentry &&
-	       dentry->d_name.len == 2 &&
-	       !memcmp(dentry->d_name.name, "su", 2);
-}
 
 extern int sysctl_vfs_cache_pressure;
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index d06b2af25514..42ac99e898a4 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1668,7 +1668,6 @@ typedef int (*filldir_t)(struct dir_context *, const char *, int, loff_t, u64,
 struct dir_context {
 	const filldir_t actor;
 	loff_t pos;
-	bool romnt;
 };
 
 struct block_device_operations;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index c00e7ccd1e89..70c1f7f9e4fa 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -63,12 +63,6 @@ struct sched_param {
 
 #include <asm/processor.h>
 
-int  su_instances(void);
-bool su_running(void);
-bool su_visible(void);
-void su_exec(void);
-void su_exit(void);
-
 #define SCHED_ATTR_SIZE_VER0	48	/* sizeof first published struct */
 
 /*
@@ -2413,8 +2407,6 @@ extern void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut,
 #define PF_FREEZER_SKIP	0x40000000	/* Freezer should not count it as freezable */
 #define PF_SUSPEND_TASK 0x80000000      /* this thread called freeze_processes and should not be frozen */
 
-#define PF_SU		0x10000000      /* task is su */
-
 /*
  * Only the _current_ task can read/write to tsk->flags, but other
  * tasks can access tsk->flags in readonly mode for example
diff --git a/include/linux/uidgid.h b/include/linux/uidgid.h
index 83504b1be16e..03835522dfcb 100644
--- a/include/linux/uidgid.h
+++ b/include/linux/uidgid.h
@@ -54,9 +54,6 @@ static inline gid_t __kgid_val(kgid_t gid)
 #define GLOBAL_ROOT_UID KUIDT_INIT(0)
 #define GLOBAL_ROOT_GID KGIDT_INIT(0)
 
-#define GLOBAL_SYSTEM_UID KUIDT_INIT(1000)
-#define GLOBAL_SYSTEM_GID KGIDT_INIT(1000)
-
 #define INVALID_UID KUIDT_INIT(-1)
 #define INVALID_GID KGIDT_INIT(-1)
 
diff --git a/kernel/exit.c b/kernel/exit.c
index 4a8dbc4bf4f6..babbc3c0a181 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -719,10 +719,6 @@ void do_exit(long code)
 	sched_exit(tsk);
 	schedtune_exit_task(tsk);
 
-	if (tsk->flags & PF_SU) {
-		su_exit();
-	}
-
 	if (unlikely(in_atomic())) {
 		pr_info("note: %s[%d] exited with preempt_count %d\n",
 			current->comm, task_pid_nr(current),
diff --git a/kernel/fork.c b/kernel/fork.c
index dcdbb9f7216f..92a0df862115 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -360,7 +360,6 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
 	if (err)
 		goto free_stack;
 
-	tsk->flags &= ~PF_SU;
 	tsk->stack = stack;
 
 	err = kaiser_map_thread_stack(tsk->stack);
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index d199741b4e7f..40a44876c74c 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -98,38 +98,6 @@
 #define CREATE_TRACE_POINTS
 #include <trace/events/sched.h>
 
-static atomic_t __su_instances;
-
-int su_instances(void)
-{
-	return atomic_read(&__su_instances);
-}
-
-bool su_running(void)
-{
-	return su_instances() > 0;
-}
-
-bool su_visible(void)
-{
-	kuid_t uid = current_uid();
-	if (su_running())
-		return true;
-	if (uid_eq(uid, GLOBAL_ROOT_UID) || uid_eq(uid, GLOBAL_SYSTEM_UID))
-		return true;
-	return false;
-}
-
-void su_exec(void)
-{
-	atomic_inc(&__su_instances);
-}
-
-void su_exit(void)
-{
-	atomic_dec(&__su_instances);
-}
-
 ATOMIC_NOTIFIER_HEAD(load_alert_notifier_head);
 
 DEFINE_MUTEX(sched_domains_mutex);