From dd6595e90768ea30a0a41d96ceb5da3cc1916bd2 Mon Sep 17 00:00:00 2001
From: Alexey Makhalov <amakhalov@vmware.com>
Date: Wed, 16 Aug 2017 21:14:17 +0000
Subject: [PATCH] Implement the f*xattrat family of functions
Inspired by https://lkml.org/lkml/2014/1/21/266
---
arch/x86/entry/syscalls/syscall_64.tbl | 4 ++
fs/xattr.c | 123 +++++++++++++++++++++++++++++++++
include/linux/syscalls.h | 11 ++-
4 files changed, 141 insertions(+), 1 deletion(-)
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index 314a90b..3c2dfa1 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -339,6 +339,14 @@
330 common pkey_alloc sys_pkey_alloc
331 common pkey_free sys_pkey_free
+
+#
+# Photon OS specific syscalls.
+#
+508 common fsetxattrat sys_fsetxattrat
+509 common fgetxattrat sys_fgetxattrat
+510 common flistxattrat sys_flistxattrat
+511 common fremovexattrat sys_fremovexattrat
#
# x32-specific system call numbers start at 512 to avoid cache impact
# for native 64-bit operation.
diff --git a/fs/xattr.c b/fs/xattr.c
index f0da9d2..d5e4944 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -419,6 +419,41 @@ SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
return error;
}
+SYSCALL_DEFINE6(fsetxattrat, int, fd, const char __user *, pathname,
+ const char __user *, name, const void __user *, value,
+ size_t, size, int, flags)
+{
+ struct path path;
+ int error;
+ unsigned int lookup_flags = 0;
+
+ if (flags & ~(XATTR_CREATE | XATTR_REPLACE |
+ AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
+ return -EINVAL;
+
+ if (!(flags & AT_SYMLINK_NOFOLLOW))
+ lookup_flags |= LOOKUP_FOLLOW;
+ if (flags & AT_EMPTY_PATH)
+ lookup_flags |= LOOKUP_EMPTY;
+
+retry:
+ error = user_path_at(fd, pathname, lookup_flags, &path);
+ if (error)
+ return error;
+ error = mnt_want_write(path.mnt);
+ if (!error) {
+ error = setxattr(path.dentry, name, value, size,
+ flags & (XATTR_CREATE | XATTR_REPLACE));
+ mnt_drop_write(path.mnt);
+ }
+ path_put(&path);
+ if (retry_estale(error, lookup_flags)) {
+ lookup_flags |= LOOKUP_REVAL;
+ goto retry;
+ }
+ return error;
+}
+
/*
* Extended attribute GET operations
*/
@@ -513,6 +548,35 @@ SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
return error;
}
+SYSCALL_DEFINE6(fgetxattrat, int, fd, const char __user *, pathname,
+ const char __user *, name, void __user *, value, size_t, size,
+ int, flags)
+{
+ struct path path;
+ ssize_t error;
+ unsigned int lookup_flags = 0;
+
+ if (flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
+ return -EINVAL;
+
+ if (!(flags & AT_SYMLINK_NOFOLLOW))
+ lookup_flags |= LOOKUP_FOLLOW;
+ if (flags & AT_EMPTY_PATH)
+ lookup_flags |= LOOKUP_EMPTY;
+
+retry:
+ error = user_path_at(fd, pathname, lookup_flags, &path);
+ if (error)
+ return error;
+ error = getxattr(path.dentry, name, value, size);
+ path_put(&path);
+ if (retry_estale(error, lookup_flags)) {
+ lookup_flags |= LOOKUP_REVAL;
+ goto retry;
+ }
+ return error;
+}
+
/*
* Extended attribute LIST operations
*/
@@ -594,6 +658,34 @@ SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)
return error;
}
+SYSCALL_DEFINE5(flistxattrat, int, fd, const char __user *, pathname,
+ char __user *, list, size_t, size, int, flags)
+{
+ struct path path;
+ ssize_t error;
+ unsigned int lookup_flags = 0;
+
+ if (flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
+ return -EINVAL;
+
+ if (!(flags & AT_SYMLINK_NOFOLLOW))
+ lookup_flags |= LOOKUP_FOLLOW;
+ if (flags & AT_EMPTY_PATH)
+ lookup_flags |= LOOKUP_EMPTY;
+
+retry:
+ error = user_path_at(fd, pathname, lookup_flags, &path);
+ if (error)
+ return error;
+ error = listxattr(path.dentry, list, size);
+ path_put(&path);
+ if (retry_estale(error, lookup_flags)) {
+ lookup_flags |= LOOKUP_REVAL;
+ goto retry;
+ }
+ return error;
+}
+
/*
* Extended attribute REMOVE operations
*/
@@ -663,6 +755,38 @@ SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
return error;
}
+SYSCALL_DEFINE4(fremovexattrat, int, fd, const char __user *, pathname,
+ const char __user *, name, int, flags)
+{
+ struct path path;
+ int error;
+ unsigned int lookup_flags = 0;
+
+ if (flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
+ return -EINVAL;
+
+ if (!(flags & AT_SYMLINK_NOFOLLOW))
+ lookup_flags |= LOOKUP_FOLLOW;
+ if (flags & AT_EMPTY_PATH)
+ lookup_flags |= LOOKUP_EMPTY;
+
+retry:
+ error = user_path_at(fd, pathname, lookup_flags, &path);
+ if (error)
+ return error;
+ error = mnt_want_write(path.mnt);
+ if (!error) {
+ error = removexattr(path.dentry, name);
+ mnt_drop_write(path.mnt);
+ }
+ path_put(&path);
+ if (retry_estale(error, lookup_flags)) {
+ lookup_flags |= LOOKUP_REVAL;
+ goto retry;
+ }
+ return error;
+}
+
/*
* Combine the results of the list() operation from every xattr_handler in the
* list.
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index c2b66a2..daf1856 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -430,23 +430,32 @@ asmlinkage long sys_lsetxattr(const char __user *path, const char __user *name,
const void __user *value, size_t size, int flags);
asmlinkage long sys_fsetxattr(int fd, const char __user *name,
const void __user *value, size_t size, int flags);
+asmlinkage long sys_fsetxattrat(int fd, const char __user *pathname,
+ const char __user *name,
+ const void __user *value, size_t size, int flags);
asmlinkage long sys_getxattr(const char __user *path, const char __user *name,
void __user *value, size_t size);
asmlinkage long sys_lgetxattr(const char __user *path, const char __user *name,
void __user *value, size_t size);
asmlinkage long sys_fgetxattr(int fd, const char __user *name,
void __user *value, size_t size);
+asmlinkage long sys_fgetxattrat(int fd, const char __user *pathname,
+ const char __user *name,
+ void __user *value, size_t size, int flags);
asmlinkage long sys_listxattr(const char __user *path, char __user *list,
size_t size);
asmlinkage long sys_llistxattr(const char __user *path, char __user *list,
size_t size);
asmlinkage long sys_flistxattr(int fd, char __user *list, size_t size);
+asmlinkage long sys_flistxattrat(int fd, const char __user *pathname,
+ char __user *list, size_t size, int flags);
asmlinkage long sys_removexattr(const char __user *path,
const char __user *name);
asmlinkage long sys_lremovexattr(const char __user *path,
const char __user *name);
asmlinkage long sys_fremovexattr(int fd, const char __user *name);
-
+asmlinkage long sys_fremovexattrat(int fd, const char __user *pathname,
+ const char __user *name, int flags);
asmlinkage long sys_brk(unsigned long brk);
asmlinkage long sys_mprotect(unsigned long start, size_t len,
unsigned long prot);
--
2.8.1