From 3a8bec33ef8c141bbed385909913b110c674f0e5 Mon Sep 17 00:00:00 2001 From: Hans Petter Selasky Date: Thu, 12 May 2016 11:38:28 +0000 Subject: [PATCH] Fix handling of IOCTLs in the LinuxKPI. Linux requires that all IOCTL data resides in userspace. FreeBSD always moves the main IOCTL structure into a kernel buffer before invoking the IOCTL handler and then copies it back into userspace, before returning. Hide this difference in the "linux_copyin()" and "linux_copyout()" functions by remapping userspace addresses in the range from 0x10000 to 0x20000, to the kernel IOCTL data buffer. It is assumed that the userspace code, data and stack segments starts no lower than memory address 0x400000, which is also stated by "man 1 ld", which means any valid userspace pointer can be passed to regular LinuxKPI handled IOCTLs. Bump the FreeBSD version to force recompilation of all kernel modules. Discussed with: kmacy @ MFC after: 1 week Sponsored by: Mellanox Technologies --- .../linuxkpi/common/include/asm/uaccess.h | 4 +- .../linuxkpi/common/include/linux/sched.h | 2 + .../linuxkpi/common/include/linux/uaccess.h | 26 +++--- sys/compat/linuxkpi/common/src/linux_compat.c | 85 +++++++++++++++++-- sys/sys/param.h | 2 +- 5 files changed, 98 insertions(+), 21 deletions(-) diff --git a/sys/compat/linuxkpi/common/include/asm/uaccess.h b/sys/compat/linuxkpi/common/include/asm/uaccess.h index ce90355220f..f3e743f1b39 100644 --- a/sys/compat/linuxkpi/common/include/asm/uaccess.h +++ b/sys/compat/linuxkpi/common/include/asm/uaccess.h @@ -36,7 +36,7 @@ static inline long copy_to_user(void *to, const void *from, unsigned long n) { - if (copyout(from, to, n) != 0) + if (linux_copyout(from, to, n) != 0) return n; return 0; } @@ -44,7 +44,7 @@ copy_to_user(void *to, const void *from, unsigned long n) static inline long copy_from_user(void *to, const void *from, unsigned long n) { - if (copyin(from, to, n) != 0) + if (linux_copyin(from, to, n) != 0) return n; return 0; } diff --git a/sys/compat/linuxkpi/common/include/linux/sched.h b/sys/compat/linuxkpi/common/include/linux/sched.h index ca1effe8860..bdaf7ae070f 100644 --- a/sys/compat/linuxkpi/common/include/linux/sched.h +++ b/sys/compat/linuxkpi/common/include/linux/sched.h @@ -66,6 +66,8 @@ struct task_struct { int should_stop; pid_t pid; const char *comm; + void *bsd_ioctl_data; + unsigned bsd_ioctl_len; }; #define current task_struct_get(curthread) diff --git a/sys/compat/linuxkpi/common/include/linux/uaccess.h b/sys/compat/linuxkpi/common/include/linux/uaccess.h index e44024ec56d..2cfd950ab4d 100644 --- a/sys/compat/linuxkpi/common/include/linux/uaccess.h +++ b/sys/compat/linuxkpi/common/include/linux/uaccess.h @@ -34,19 +34,23 @@ #include -#define __get_user(_x, _p) ({ \ - int __err; \ - __typeof(*(_p)) __x; \ - __err = -copyin((_p), &(__x), sizeof(*(_p))); \ - (_x) = __x; \ - __err; \ +#define __get_user(_x, _p) ({ \ + int __err; \ + __typeof(*(_p)) __x; \ + __err = linux_copyin((_p), &(__x), sizeof(*(_p))); \ + (_x) = __x; \ + __err; \ }) -#define __put_user(_x, _p) ({ \ - __typeof(*(_p)) __x = (_x); \ - -copyout(&(__x), (_p), sizeof(*(_p))); \ + +#define __put_user(_x, _p) ({ \ + __typeof(*(_p)) __x = (_x); \ + linux_copyout(&(__x), (_p), sizeof(*(_p))); \ }) -#define get_user(_x, _p) -copyin((_p), &(_x), sizeof(*(_p))) -#define put_user(_x, _p) -copyout(&(_x), (_p), sizeof(*(_p))) +#define get_user(_x, _p) linux_copyin((_p), &(_x), sizeof(*(_p))) +#define put_user(_x, _p) linux_copyout(&(_x), (_p), sizeof(*(_p))) + +extern int linux_copyin(const void *uaddr, void *kaddr, size_t len); +extern int linux_copyout(const void *kaddr, void *uaddr, size_t len); /* * NOTE: The returned value from pagefault_disable() must be stored diff --git a/sys/compat/linuxkpi/common/src/linux_compat.c b/sys/compat/linuxkpi/common/src/linux_compat.c index a03063bc9f6..0584f23ee9e 100644 --- a/sys/compat/linuxkpi/common/src/linux_compat.c +++ b/sys/compat/linuxkpi/common/src/linux_compat.c @@ -66,6 +66,7 @@ __FBSDID("$FreeBSD$"); #include #include #include +#include #include @@ -461,6 +462,66 @@ linux_dev_close(struct cdev *dev, int fflag, int devtype, struct thread *td) return (0); } +#define LINUX_IOCTL_MIN_PTR 0x10000UL +#define LINUX_IOCTL_MAX_PTR (LINUX_IOCTL_MIN_PTR + IOCPARM_MAX) + +static inline int +linux_remap_address(void **uaddr, size_t len) +{ + uintptr_t uaddr_val = (uintptr_t)(*uaddr); + + if (unlikely(uaddr_val >= LINUX_IOCTL_MIN_PTR && + uaddr_val < LINUX_IOCTL_MAX_PTR)) { + struct task_struct *pts = current; + if (pts == NULL) { + *uaddr = NULL; + return (1); + } + + /* compute data offset */ + uaddr_val -= LINUX_IOCTL_MIN_PTR; + + /* check that length is within bounds */ + if ((len > IOCPARM_MAX) || + (uaddr_val + len) > pts->bsd_ioctl_len) { + *uaddr = NULL; + return (1); + } + + /* re-add kernel buffer address */ + uaddr_val += (uintptr_t)pts->bsd_ioctl_data; + + /* update address location */ + *uaddr = (void *)uaddr_val; + return (1); + } + return (0); +} + +int +linux_copyin(const void *uaddr, void *kaddr, size_t len) +{ + if (linux_remap_address(__DECONST(void **, &uaddr), len)) { + if (uaddr == NULL) + return (-EFAULT); + memcpy(kaddr, uaddr, len); + return (0); + } + return (-copyin(uaddr, kaddr, len)); +} + +int +linux_copyout(const void *kaddr, void *uaddr, size_t len) +{ + if (linux_remap_address(&uaddr, len)) { + if (uaddr == NULL) + return (-EFAULT); + memcpy(uaddr, kaddr, len); + return (0); + } + return (-copyout(kaddr, uaddr, len)); +} + static int linux_dev_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int fflag, struct thread *td) @@ -469,6 +530,7 @@ linux_dev_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int fflag, struct linux_file *filp; struct task_struct t; struct file *file; + unsigned size; int error; file = td->td_fpop; @@ -479,13 +541,22 @@ linux_dev_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int fflag, return (error); filp->f_flags = file->f_flag; linux_set_current(td, &t); - /* - * Linux does not have a generic ioctl copyin/copyout layer. All - * linux ioctls must be converted to void ioctls which pass a - * pointer to the address of the data. We want the actual user - * address so we dereference here. - */ - data = *(void **)data; + size = IOCPARM_LEN(cmd); + /* refer to logic in sys_ioctl() */ + if (size > 0) { + /* + * Setup hint for linux_copyin() and linux_copyout(). + * + * Background: Linux code expects a user-space address + * while FreeBSD supplies a kernel-space address. + */ + t.bsd_ioctl_data = data; + t.bsd_ioctl_len = size; + data = (void *)LINUX_IOCTL_MIN_PTR; + } else { + /* fetch user-space pointer */ + data = *(void **)data; + } if (filp->f_op->unlocked_ioctl) error = -filp->f_op->unlocked_ioctl(filp, cmd, (u_long)data); else diff --git a/sys/sys/param.h b/sys/sys/param.h index 6c64074d41d..5074c5ad537 100644 --- a/sys/sys/param.h +++ b/sys/sys/param.h @@ -58,7 +58,7 @@ * in the range 5 to 9. */ #undef __FreeBSD_version -#define __FreeBSD_version 1100107 /* Master, propagated to newvers */ +#define __FreeBSD_version 1100108 /* Master, propagated to newvers */ /* * __FreeBSD_kernel__ indicates that this system uses the kernel of FreeBSD,