diff options
authorDominik Brodowski <linux@dominikbrodowski.net>2018-03-11 11:34:49 +0100
committerDominik Brodowski <linux@dominikbrodowski.net>2018-04-02 20:15:55 +0200
commitb724e846b491ef8db943be8086226c9d8da31877 (patch)
parent0101db7a301981a008296d522d8c1f456b0fe837 (diff)
fs: add do_symlinkat() helper and ksys_symlink() wrapper; remove in-kernel calls to syscall
Using the fs-internal do_symlinkat() helper allows us to get rid of fs-internal calls to the sys_symlinkat() syscall. Introducing the ksys_symlink() wrapper allows us to avoid the in-kernel calls to the sys_symlink() syscall. The ksys_ prefix denotes that this function is meant as a drop-in replacement for the syscall. In particular, it uses the same calling convention as sys_symlink(). This patch is part of a series which removes in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. For details, see http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
4 files changed, 21 insertions, 4 deletions
diff --git a/fs/internal.h b/fs/internal.h
index 53846bd4d9d7..a3f04ca2a08b 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -58,6 +58,8 @@ extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
long do_mkdirat(int dfd, const char __user *pathname, umode_t mode);
long do_rmdir(int dfd, const char __user *pathname);
long do_unlinkat(int dfd, struct filename *name);
+long do_symlinkat(const char __user *oldname, int newdfd,
+ const char __user *newname);
* namespace.c
diff --git a/fs/namei.c b/fs/namei.c
index dcf506227509..e15da92209d5 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -4113,8 +4113,8 @@ int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
-SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
- int, newdfd, const char __user *, newname)
+long do_symlinkat(const char __user *oldname, int newdfd,
+ const char __user *newname)
int error;
struct filename *from;
@@ -4144,9 +4144,15 @@ out_putname:
return error;
+SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
+ int, newdfd, const char __user *, newname)
+ return do_symlinkat(oldname, newdfd, newname);
SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname)
- return sys_symlinkat(oldname, AT_FDCWD, newname);
+ return do_symlinkat(oldname, AT_FDCWD, newname);
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index c982cb5f4e50..39c5cef86a10 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -979,4 +979,13 @@ static inline long ksys_mkdir(const char __user *pathname, umode_t mode)
return do_mkdirat(AT_FDCWD, pathname, mode);
+extern long do_symlinkat(const char __user *oldname, int newdfd,
+ const char __user *newname);
+static inline long ksys_symlink(const char __user *oldname,
+ const char __user *newname)
+ return do_symlinkat(oldname, AT_FDCWD, newname);
diff --git a/init/initramfs.c b/init/initramfs.c
index ca538a5f9fa9..cd9571a113b6 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -392,7 +392,7 @@ static int __init do_symlink(void)
collected[N_ALIGN(name_len) + body_len] = '\0';
clean_path(collected, 0);
- sys_symlink(collected + N_ALIGN(name_len), collected);
+ ksys_symlink(collected + N_ALIGN(name_len), collected);
sys_lchown(collected, uid, gid);
do_utime(collected, mtime);
state = SkipIt;

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