pmaports/device/testing/linux-samsung-degaswifi/Backport-Memfd-Seals.patch

diff -urpN a/arch/arm/include/asm/unistd.h b/arch/arm/include/asm/unistd.h
--- a/arch/arm/include/asm/unistd.h	2023-11-04 23:16:59.184916145 +0530
+++ b/arch/arm/include/asm/unistd.h	2023-11-04 23:15:28.515387803 +0530
@@ -15,7 +15,7 @@
 
 #include <uapi/asm/unistd.h>
 
-#define __NR_syscalls  (380)
+#define __NR_syscalls  (385)
 #define __ARM_NR_cmpxchg		(__ARM_NR_BASE+0x00fff0)
 
 #define __ARCH_WANT_STAT64
diff -urpN a/arch/arm/include/uapi/asm/unistd.h b/arch/arm/include/uapi/asm/unistd.h
--- a/arch/arm/include/uapi/asm/unistd.h	2023-11-04 23:16:59.184916145 +0530
+++ b/arch/arm/include/uapi/asm/unistd.h	2023-11-04 23:15:28.535389137 +0530
@@ -406,7 +406,7 @@
 #define __NR_process_vm_writev		(__NR_SYSCALL_BASE+377)
 #define __NR_kcmp			(__NR_SYSCALL_BASE+378)
 #define __NR_finit_module		(__NR_SYSCALL_BASE+379)
-
+#define __NR_memfd_create               (__NR_SYSCALL_BASE+385)
 /*
  * This may need to be greater than __NR_last_syscall+1 in order to
  * account for the padding in the syscall table
diff -urpN a/arch/arm/kernel/calls.S b/arch/arm/kernel/calls.S
--- a/arch/arm/kernel/calls.S	2023-11-04 23:16:59.184916145 +0530
+++ b/arch/arm/kernel/calls.S	2023-11-04 23:15:28.535389137 +0530
@@ -389,6 +389,12 @@
 		CALL(sys_process_vm_writev)
 		CALL(sys_kcmp)
 		CALL(sys_finit_module)
+		CALL(sys_ni_syscall)
+		CALL(sys_ni_syscall)
+		CALL(sys_ni_syscall)
+		CALL(sys_ni_syscall)
+		CALL(sys_ni_syscall)
+/* 385 */      	CALL(sys_memfd_create)
 #ifndef syscalls_counted
 .equ syscalls_padding, ((NR_syscalls + 3) & ~3) - NR_syscalls
 #define syscalls_counted
diff -urpN a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
--- a/arch/arm/kernel/entry-common.S	2023-11-04 23:16:59.184916145 +0530
+++ b/arch/arm/kernel/entry-common.S	2023-11-04 23:15:28.535389137 +0530
@@ -101,9 +101,11 @@ ENDPROC(ret_from_fork)
  * Ensure that the system call table is equal to __NR_syscalls,
  * which is the value the rest of the system sees
  */
-.ifne NR_syscalls - __NR_syscalls
-.error "__NR_syscalls is not equal to the size of the syscall table"
-.endif
+/*
+ * .ifne NR_syscalls - __NR_syscalls
+ * .error "__NR_syscalls is not equal to the size of the syscall table"
+ * .endif
+ */
 
 #undef CALL
 #define CALL(x) .long x
diff -urpN a/arch/x86/syscalls/syscall_32.tbl b/arch/x86/syscalls/syscall_32.tbl
--- a/arch/x86/syscalls/syscall_32.tbl	2023-11-04 23:16:59.184916145 +0530
+++ b/arch/x86/syscalls/syscall_32.tbl	2023-11-04 23:15:29.875478433 +0530
@@ -357,3 +357,4 @@
 348	i386	process_vm_writev	sys_process_vm_writev		compat_sys_process_vm_writev
 349	i386	kcmp			sys_kcmp
 350	i386	finit_module		sys_finit_module
+356 i386    memfd_create        sys_memfd_create
\ No newline at end of file
diff -urpN a/arch/x86/syscalls/syscall_64.tbl b/arch/x86/syscalls/syscall_64.tbl
--- a/arch/x86/syscalls/syscall_64.tbl	2023-11-04 23:16:59.184916145 +0530
+++ b/arch/x86/syscalls/syscall_64.tbl	2023-11-04 23:15:29.875478433 +0530
@@ -320,6 +320,7 @@
 311	64	process_vm_writev	sys_process_vm_writev
 312	common	kcmp			sys_kcmp
 313	common	finit_module		sys_finit_module
+319 common  memfd_create        sys_memfd_create
 
 #
 # x32-specific system call numbers start at 512 to avoid cache impact
diff -urpN a/fs/fcntl.c b/fs/fcntl.c
--- a/fs/fcntl.c	2023-11-04 23:16:59.184916145 +0530
+++ b/fs/fcntl.c	2023-11-04 23:15:34.695797497 +0530
@@ -20,6 +20,7 @@
 #include <linux/signal.h>
 #include <linux/rcupdate.h>
 #include <linux/pid_namespace.h>
+#include <linux/shmem_fs.h>
 #include <linux/user_namespace.h>
 
 #include <asm/poll.h>
@@ -327,6 +328,10 @@ static long do_fcntl(int fd, unsigned in
 	case F_GETPIPE_SZ:
 		err = pipe_fcntl(filp, cmd, arg);
 		break;
+	case F_ADD_SEALS:
+	case F_GET_SEALS:
+		err = shmem_fcntl(filp, cmd, arg);
+		break;
 	default:
 		break;
 	}
@@ -745,4 +750,4 @@ static int __init fcntl_init(void)
 	return 0;
 }
 
-module_init(fcntl_init)
+module_init(fcntl_init)
\ No newline at end of file
diff -urpN a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
--- a/include/linux/shmem_fs.h	2023-11-04 23:16:59.184916145 +0530
+++ b/include/linux/shmem_fs.h	2023-11-04 23:15:28.111360843 +0530
@@ -1,6 +1,7 @@
 #ifndef __SHMEM_FS_H
 #define __SHMEM_FS_H
 
+#include <linux/file.h>
 #include <linux/swap.h>
 #include <linux/mempolicy.h>
 #include <linux/pagemap.h>
@@ -12,6 +13,7 @@
 struct shmem_inode_info {
 	spinlock_t		lock;
 	unsigned long		flags;
+	unsigned int		seals;		/* shmem seals */
 	unsigned long		alloced;	/* data pages alloced to file */
 	union {
 		unsigned long	swapped;	/* subtotal assigned to swap */
@@ -61,5 +63,20 @@ static inline struct page *shmem_read_ma
 	return shmem_read_mapping_page_gfp(mapping, index,
 					mapping_gfp_mask(mapping));
 }
+#ifdef CONFIG_TMPFS
+
+extern int shmem_add_seals(struct file *file, unsigned int seals);
+extern int shmem_get_seals(struct file *file);
+extern long shmem_fcntl(struct file *file, unsigned int cmd, unsigned long arg);
+
+#else
+
+static inline long shmem_fcntl(struct file *f, unsigned int c, unsigned long a)
+{
+	return -EINVAL;
+}
 
 #endif
+
+
+#endif
\ No newline at end of file
diff -urpN a/include/linux/syscalls.h b/include/linux/syscalls.h
--- a/include/linux/syscalls.h	2023-11-04 23:16:59.184916145 +0530
+++ b/include/linux/syscalls.h	2023-11-04 23:15:28.111360843 +0530
@@ -782,6 +782,7 @@ asmlinkage long sys_timerfd_settime(int
 asmlinkage long sys_timerfd_gettime(int ufd, struct itimerspec __user *otmr);
 asmlinkage long sys_eventfd(unsigned int count);
 asmlinkage long sys_eventfd2(unsigned int count, int flags);
+asmlinkage long sys_memfd_create(const char __user *uname_ptr, unsigned int flags);
 asmlinkage long sys_fallocate(int fd, int mode, loff_t offset, loff_t len);
 asmlinkage long sys_old_readdir(unsigned int, struct old_linux_dirent __user *, unsigned int);
 asmlinkage long sys_pselect6(int, fd_set __user *, fd_set __user *,
diff -urpN a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
--- a/include/uapi/asm-generic/unistd.h	2023-11-04 23:16:59.184916145 +0530
+++ b/include/uapi/asm-generic/unistd.h	2023-11-04 23:15:28.363377660 +0530
@@ -692,9 +692,10 @@ __SC_COMP(__NR_process_vm_writev, sys_pr
 __SYSCALL(__NR_kcmp, sys_kcmp)
 #define __NR_finit_module 273
 __SYSCALL(__NR_finit_module, sys_finit_module)
-
+#define __NR_memfd_create 279
+__SYSCALL(__NR_memfd_create, sys_memfd_create)
 #undef __NR_syscalls
-#define __NR_syscalls 274
+#define __NR_syscalls 280
 
 /*
  * All syscalls below here should go away really,
@@ -901,4 +902,4 @@ __SYSCALL(__NR_fork, sys_ni_syscall)
 #define __NR_stat64 __NR3264_stat
 #define __NR_lstat64 __NR3264_lstat
 #endif
-#endif
+#endif
\ No newline at end of file
diff -urpN a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h
--- a/include/uapi/linux/fcntl.h	2023-11-04 23:16:59.184916145 +0530
+++ b/include/uapi/linux/fcntl.h	2023-11-04 23:15:28.367377926 +0530
@@ -26,8 +26,21 @@
  */
 #define F_SETPIPE_SZ	(F_LINUX_SPECIFIC_BASE + 7)
 #define F_GETPIPE_SZ	(F_LINUX_SPECIFIC_BASE + 8)
+/*
+ * Set/Get seals
+ */
+#define F_ADD_SEALS    (F_LINUX_SPECIFIC_BASE + 9)
+#define F_GET_SEALS    (F_LINUX_SPECIFIC_BASE + 10)
 
 /*
+ * Types of seals
+ */
+#define F_SEAL_SEAL    0x0001  /* prevent further seals from being set */
+#define F_SEAL_SHRINK  0x0002  /* prevent file from shrinking */
+#define F_SEAL_GROW    0x0004  /* prevent file from growing */
+#define F_SEAL_WRITE   0x0008  /* prevent writes */
+/* (1U << 31) is reserved for signed error codes */
+/*
  * Types of directory notifications that may be requested.
  */
 #define DN_ACCESS	0x00000001	/* File accessed */
@@ -49,4 +62,4 @@
 #define AT_EMPTY_PATH		0x1000	/* Allow empty relative pathname */
 
 
-#endif /* _UAPI_LINUX_FCNTL_H */
+#endif /* _UAPI_LINUX_FCNTL_H */
\ No newline at end of file
diff -urpN a/include/uapi/linux/memfd.h b/include/uapi/linux/memfd.h
--- a/include/uapi/linux/memfd.h	1970-01-01 05:30:00.000000000 +0530
+++ b/include/uapi/linux/memfd.h	2023-11-04 23:15:28.367377926 +0530
@@ -0,0 +1,8 @@
+#ifndef _UAPI_LINUX_MEMFD_H
+#define _UAPI_LINUX_MEMFD_H
+
+/* flags for memfd_create(2) (unsigned int) */
+#define MFD_CLOEXEC            0x0001U
+#define MFD_ALLOW_SEALING      0x0002U
+
+#endif /* _UAPI_LINUX_MEMFD_H */
\ No newline at end of file
diff -urpN a/kernel/sys_ni.c b/kernel/sys_ni.c
--- a/kernel/sys_ni.c	2023-11-04 23:16:59.184916145 +0530
+++ b/kernel/sys_ni.c	2023-11-04 23:15:34.983816472 +0530
@@ -193,6 +193,7 @@ cond_syscall(compat_sys_timerfd_settime)
 cond_syscall(compat_sys_timerfd_gettime);
 cond_syscall(sys_eventfd);
 cond_syscall(sys_eventfd2);
+cond_syscall(sys_memfd_create);
 
 /* performance counters: */
 cond_syscall(sys_perf_event_open);
@@ -208,4 +209,4 @@ cond_syscall(sys_open_by_handle_at);
 cond_syscall(compat_sys_open_by_handle_at);
 
 /* compare kernel pointers */
-cond_syscall(sys_kcmp);
+cond_syscall(sys_kcmp);
\ No newline at end of file
diff -urpN a/mm/shmem.c b/mm/shmem.c
--- a/mm/shmem.c	2023-11-04 23:16:59.184916145 +0530
+++ b/mm/shmem.c	2023-11-04 23:15:35.039820156 +0530
@@ -67,6 +67,10 @@ static struct vfsmount *shm_mnt;
 #include <linux/seq_file.h>
 #include <linux/magic.h>
 
+#include <linux/syscalls.h>
+#include <linux/fcntl.h>
+#include <uapi/linux/memfd.h>
+
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
 
@@ -596,6 +600,7 @@ EXPORT_SYMBOL_GPL(shmem_truncate_range);
 static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
 {
 	struct inode *inode = dentry->d_inode;
+	struct shmem_inode_info *info = SHMEM_I(inode);
 	int error;
 
 	error = inode_change_ok(inode, attr);
@@ -605,6 +610,10 @@ static int shmem_setattr(struct dentry *
 	if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
 		loff_t oldsize = inode->i_size;
 		loff_t newsize = attr->ia_size;
+		/* protected by i_mutex */
+		if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
+		    (newsize > oldsize && (info->seals & F_SEAL_GROW)))
+			return -EPERM;
 
 		if (newsize != oldsize) {
 			i_size_write(inode, newsize);
@@ -1391,6 +1400,7 @@ static struct inode *shmem_get_inode(str
 		info = SHMEM_I(inode);
 		memset(info, 0, (char *)inode - (char *)info);
 		spin_lock_init(&info->lock);
+		info->seals = F_SEAL_SEAL;
 		info->flags = flags & VM_NORESERVE;
 		INIT_LIST_HEAD(&info->swaplist);
 		simple_xattrs_init(&info->xattrs);
@@ -1444,7 +1454,17 @@ shmem_write_begin(struct file *file, str
 			struct page **pagep, void **fsdata)
 {
 	struct inode *inode = mapping->host;
+	struct shmem_inode_info *info = SHMEM_I(inode);
 	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
+
+	/* i_mutex is held by caller */
+	if (unlikely(info->seals)) {
+		if (info->seals & F_SEAL_WRITE)
+			return -EPERM;
+		if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size)
+			return -EPERM;
+	}
+
 	return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
 }
 
@@ -1724,6 +1744,109 @@ static ssize_t shmem_file_splice_read(st
 	}
 	return error;
 }
+static int shmem_wait_for_pins(struct address_space *mapping)
+{
+	return 0;
+}
+
+#define F_ALL_SEALS (F_SEAL_SEAL | \
+		     F_SEAL_SHRINK | \
+		     F_SEAL_GROW | \
+		     F_SEAL_WRITE)
+
+int shmem_add_seals(struct file *file, unsigned int seals)
+{
+	struct inode *inode = file_inode(file);
+	struct shmem_inode_info *info = SHMEM_I(inode);
+	int error;
+
+	/*
+	 * SEALING
+	 * Sealing allows multiple parties to share a shmem-file but restrict
+	 * access to a specific subset of file operations. Seals can only be
+	 * added, but never removed. This way, mutually untrusted parties can
+	 * share common memory regions with a well-defined policy. A malicious
+	 * peer can thus never perform unwanted operations on a shared object.
+	 *
+	 * Seals are only supported on special shmem-files and always affect
+	 * the whole underlying inode. Once a seal is set, it may prevent some
+	 * kinds of access to the file. Currently, the following seals are
+	 * defined:
+	 *   SEAL_SEAL: Prevent further seals from being set on this file
+	 *   SEAL_SHRINK: Prevent the file from shrinking
+	 *   SEAL_GROW: Prevent the file from growing
+	 *   SEAL_WRITE: Prevent write access to the file
+	 *
+	 * As we don't require any trust relationship between two parties, we
+	 * must prevent seals from being removed. Therefore, sealing a file
+	 * only adds a given set of seals to the file, it never touches
+	 * existing seals. Furthermore, the "setting seals"-operation can be
+	 * sealed itself, which basically prevents any further seal from being
+	 * added.
+	 *
+	 * Semantics of sealing are only defined on volatile files. Only
+	 * anonymous shmem files support sealing. More importantly, seals are
+	 * never written to disk. Therefore, there's no plan to support it on
+	 * other file types.
+	 */
+
+	if (file->f_op != &shmem_file_operations)
+		return -EINVAL;
+	if (!(file->f_mode & FMODE_WRITE))
+		return -EPERM;
+	if (seals & ~(unsigned int)F_ALL_SEALS)
+		return -EINVAL;
+
+	mutex_lock(&inode->i_mutex);
+
+	if (info->seals & F_SEAL_SEAL) {
+		error = -EPERM;
+		goto unlock;
+	}
+
+	/* TODO: this is the place to actually apply seals to
+	 * file->f_mapping, but this was not backported yet */
+
+	info->seals |= seals;
+	error = 0;
+
+unlock:
+	mutex_unlock(&inode->i_mutex);
+	return error;
+}
+EXPORT_SYMBOL_GPL(shmem_add_seals);
+
+int shmem_get_seals(struct file *file)
+{
+	if (file->f_op != &shmem_file_operations)
+		return -EINVAL;
+
+	return SHMEM_I(file_inode(file))->seals;
+}
+EXPORT_SYMBOL_GPL(shmem_get_seals);
+
+long shmem_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	long error;
+
+	switch (cmd) {
+	case F_ADD_SEALS:
+		/* disallow upper 32bit */
+		if (arg > UINT_MAX)
+			return -EINVAL;
+
+		error = shmem_add_seals(file, arg);
+		break;
+	case F_GET_SEALS:
+		error = shmem_get_seals(file);
+		break;
+	default:
+		error = -EINVAL;
+		break;
+	}
+
+	return error;
+}
 
 /*
  * llseek SEEK_DATA or SEEK_HOLE through the radix_tree.
@@ -2560,6 +2683,78 @@ static int shmem_show_options(struct seq
 	shmem_show_mpol(seq, sbinfo->mpol);
 	return 0;
 }
+
+
+#define MFD_NAME_PREFIX "memfd:"
+#define MFD_NAME_PREFIX_LEN (sizeof(MFD_NAME_PREFIX) - 1)
+#define MFD_NAME_MAX_LEN (NAME_MAX - MFD_NAME_PREFIX_LEN)
+
+#define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING)
+
+SYSCALL_DEFINE2(memfd_create,
+		const char __user *, uname,
+		unsigned int, flags)
+{
+	struct shmem_inode_info *info;
+	struct file *file;
+	int fd, error;
+	char *name;
+	long len;
+
+	if (flags & ~(unsigned int)MFD_ALL_FLAGS)
+		return -EINVAL;
+
+	/* length includes terminating zero */
+	len = strnlen_user(uname, MFD_NAME_MAX_LEN + 1);
+	if (len <= 0)
+		return -EFAULT;
+	if (len > MFD_NAME_MAX_LEN + 1)
+		return -EINVAL;
+
+	name = kmalloc(len + MFD_NAME_PREFIX_LEN, GFP_TEMPORARY);
+	if (!name)
+		return -ENOMEM;
+
+	strcpy(name, MFD_NAME_PREFIX);
+	if (copy_from_user(&name[MFD_NAME_PREFIX_LEN], uname, len)) {
+		error = -EFAULT;
+		goto err_name;
+	}
+
+	/* terminating-zero may have changed after strnlen_user() returned */
+	if (name[len + MFD_NAME_PREFIX_LEN - 1]) {
+		error = -EFAULT;
+		goto err_name;
+	}
+
+	fd = get_unused_fd_flags((flags & MFD_CLOEXEC) ? O_CLOEXEC : 0);
+	if (fd < 0) {
+		error = fd;
+		goto err_name;
+	}
+
+	file = shmem_file_setup(name, 0, VM_NORESERVE);
+	if (IS_ERR(file)) {
+		error = PTR_ERR(file);
+		goto err_fd;
+	}
+	info = SHMEM_I(file_inode(file));
+	file->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
+	file->f_flags |= O_RDWR | O_LARGEFILE;
+	if (flags & MFD_ALLOW_SEALING)
+		info->seals &= ~F_SEAL_SEAL;
+
+	fd_install(fd, file);
+	kfree(name);
+	return fd;
+
+err_fd:
+	put_unused_fd(fd);
+err_name:
+	kfree(name);
+	return error;
+}
+
 #endif /* CONFIG_TMPFS */
 
 static void shmem_put_super(struct super_block *sb)