[PATCH 7/9] ARM: oabi-compat: rework fcntl64() emulation

Arnd Bergmann
2020-09-07T15:47:17Z

This is one of the last users of get_fs(), and this is fairly easy to
change, since the infrastructure for it is already there.

The replacement here is essentially a copy of the existing fcntl64()
syscall entry function.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
arch/arm/kernel/sys_oabi-compat.c | 93 ++++++++++++++++++++-----------
1 file changed, 60 insertions(+), 33 deletions(-)

diff --git a/arch/arm/kernel/sys_oabi-compat.c b/arch/arm/kernel/sys_oabi-compat.c
index d3c6460d13ca..13956d5e50d7 100644
--- a/arch/arm/kernel/sys_oabi-compat.c
+++ b/arch/arm/kernel/sys_oabi-compat.c
@@ -194,56 +194,83 @@ struct oabi_flock64 {
pid_t l_pid;
} __attribute__ ((packed,aligned(4)));

-static long do_locks(unsigned int fd, unsigned int cmd,
- unsigned long arg)
+static int get_oabi_flock(struct flock64 *kernel, struct oabi_flock64 __user *arg)
{
- struct flock64 kernel;
struct oabi_flock64 user;
- mm_segment_t fs;
- long ret;

if (copy_from_user(&user, (struct oabi_flock64 __user *)arg,
sizeof(user)))
return -EFAULT;
- kernel.l_type = user.l_type;
- kernel.l_whence = user.l_whence;
- kernel.l_start = user.l_start;
- kernel.l_len = user.l_len;
- kernel.l_pid = user.l_pid;
-
- fs = get_fs();
- set_fs(KERNEL_DS);
- ret = sys_fcntl64(fd, cmd, (unsigned long)&kernel);
- set_fs(fs);
-
- if (!ret && (cmd == F_GETLK64 || cmd == F_OFD_GETLK)) {
- user.l_type = kernel.l_type;
- user.l_whence = kernel.l_whence;
- user.l_start = kernel.l_start;
- user.l_len = kernel.l_len;
- user.l_pid = kernel.l_pid;
- if (copy_to_user((struct oabi_flock64 __user *)arg,
- &user, sizeof(user)))
- ret = -EFAULT;
- }
- return ret;
+
+ kernel->l_type = user.l_type;
+ kernel->l_whence = user.l_whence;
+ kernel->l_start = user.l_start;
+ kernel->l_len = user.l_len;
+ kernel->l_pid = user.l_pid;
+
+ return 0;
+}
+
+static int put_oabi_flock(struct flock64 *kernel, struct oabi_flock64 __user *arg)
+{
+ struct oabi_flock64 user;
+
+ user.l_type = kernel->l_type;
+ user.l_whence = kernel->l_whence;
+ user.l_start = kernel->l_start;
+ user.l_len = kernel->l_len;
+ user.l_pid = kernel->l_pid;
+
+ if (copy_to_user((struct oabi_flock64 __user *)arg,
+ &user, sizeof(user)))
+ return -EFAULT;
+
+ return 0;
}

asmlinkage long sys_oabi_fcntl64(unsigned int fd, unsigned int cmd,
unsigned long arg)
{
+ void __user *argp = (void __user *)arg;
+ struct fd f = fdget_raw(fd);
+ struct flock64 flock;
+ long err = -EBADF;
+
+ if (!f.file)
+ goto out;
+
switch (cmd) {
- case F_OFD_GETLK:
- case F_OFD_SETLK:
- case F_OFD_SETLKW:
case F_GETLK64:
+ case F_OFD_GETLK:
+ err = security_file_fcntl(f.file, cmd, arg);
+ if (err)
+ break;
+ err = get_oabi_flock(&flock, argp);
+ if (err)
+ break;
+ err = fcntl_getlk64(f.file, cmd, &flock);
+ if (!err)
+ err = put_oabi_flock(&flock, argp);
+ break;
case F_SETLK64:
case F_SETLKW64:
- return do_locks(fd, cmd, arg);
-
+ case F_OFD_SETLK:
+ case F_OFD_SETLKW:
+ err = security_file_fcntl(f.file, cmd, arg);
+ if (err)
+ break;
+ err = get_oabi_flock(&flock, argp);
+ if (err)
+ break;
+ err = fcntl_setlk64(fd, f.file, cmd, &flock);
+ break;
default:
- return sys_fcntl64(fd, cmd, arg);
+ err = sys_fcntl64(fd, cmd, arg);
+ break;
}
+ fdput(f);
+out:
+ return err;
}

struct oabi_epoll_event {
--
2.27.0