From 70f1b0d34bdf03065fe869e93cc17cad1ea20c4a Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Thu, 7 Feb 2019 19:44:12 -0600 Subject: signal/usb: Replace kill_pid_info_as_cred with kill_pid_usb_asyncio The usb support for asyncio encoded one of it's values in the wrong field. It should have used si_value but instead used si_addr which is not present in the _rt union member of struct siginfo. The practical result of this is that on a 64bit big endian kernel when delivering a signal to a 32bit process the si_addr field is set to NULL, instead of the expected pointer value. This issue can not be fixed in copy_siginfo_to_user32 as the usb usage of the the _sigfault (aka si_addr) member of the siginfo union when SI_ASYNCIO is set is incompatible with the POSIX and glibc usage of the _rt member of the siginfo union. Therefore replace kill_pid_info_as_cred with kill_pid_usb_asyncio a dedicated function for this one specific case. There are no other users of kill_pid_info_as_cred so this specialization should have no impact on the amount of code in the kernel. Have kill_pid_usb_asyncio take instead of a siginfo_t which is difficult and error prone, 3 arguments, a signal number, an errno value, and an address enconded as a sigval_t. The encoding of the address as a sigval_t allows the code that reads the userspace request for a signal to handle this compat issue along with all of the other compat issues. Add BUILD_BUG_ONs in kernel/signal.c to ensure that we can now place the pointer value at the in si_pid (instead of si_addr). That is the code now verifies that si_pid and si_addr always occur at the same location. Further the code veries that for native structures a value placed in si_pid and spilling into si_uid will appear in userspace in si_addr (on a byte by byte copy of siginfo or a field by field copy of siginfo). The code also verifies that for a 64bit kernel and a 32bit userspace the 32bit pointer will fit in si_pid. I have used the usbsig.c program below written by Alan Stern and slightly tweaked by me to run on a big endian machine to verify the issue exists (on sparc64) and to confirm the patch below fixes the issue. /* usbsig.c -- test USB async signal delivery */ #define _GNU_SOURCE #include #include #include #include #include #include #include #include #include static struct usbdevfs_urb urb; static struct usbdevfs_disconnectsignal ds; static volatile sig_atomic_t done = 0; void urb_handler(int sig, siginfo_t *info , void *ucontext) { printf("Got signal %d, signo %d errno %d code %d addr: %p urb: %p\n", sig, info->si_signo, info->si_errno, info->si_code, info->si_addr, &urb); printf("%s\n", (info->si_addr == &urb) ? "Good" : "Bad"); } void ds_handler(int sig, siginfo_t *info , void *ucontext) { printf("Got signal %d, signo %d errno %d code %d addr: %p ds: %p\n", sig, info->si_signo, info->si_errno, info->si_code, info->si_addr, &ds); printf("%s\n", (info->si_addr == &ds) ? "Good" : "Bad"); done = 1; } int main(int argc, char **argv) { char *devfilename; int fd; int rc; struct sigaction act; struct usb_ctrlrequest *req; void *ptr; char buf[80]; if (argc != 2) { fprintf(stderr, "Usage: usbsig device-file-name\n"); return 1; } devfilename = argv[1]; fd = open(devfilename, O_RDWR); if (fd == -1) { perror("Error opening device file"); return 1; } act.sa_sigaction = urb_handler; sigemptyset(&act.sa_mask); act.sa_flags = SA_SIGINFO; rc = sigaction(SIGUSR1, &act, NULL); if (rc == -1) { perror("Error in sigaction"); return 1; } act.sa_sigaction = ds_handler; sigemptyset(&act.sa_mask); act.sa_flags = SA_SIGINFO; rc = sigaction(SIGUSR2, &act, NULL); if (rc == -1) { perror("Error in sigaction"); return 1; } memset(&urb, 0, sizeof(urb)); urb.type = USBDEVFS_URB_TYPE_CONTROL; urb.endpoint = USB_DIR_IN | 0; urb.buffer = buf; urb.buffer_length = sizeof(buf); urb.signr = SIGUSR1; req = (struct usb_ctrlrequest *) buf; req->bRequestType = USB_DIR_IN | USB_TYPE_STANDARD | USB_RECIP_DEVICE; req->bRequest = USB_REQ_GET_DESCRIPTOR; req->wValue = htole16(USB_DT_DEVICE << 8); req->wIndex = htole16(0); req->wLength = htole16(sizeof(buf) - sizeof(*req)); rc = ioctl(fd, USBDEVFS_SUBMITURB, &urb); if (rc == -1) { perror("Error in SUBMITURB ioctl"); return 1; } rc = ioctl(fd, USBDEVFS_REAPURB, &ptr); if (rc == -1) { perror("Error in REAPURB ioctl"); return 1; } memset(&ds, 0, sizeof(ds)); ds.signr = SIGUSR2; ds.context = &ds; rc = ioctl(fd, USBDEVFS_DISCSIGNAL, &ds); if (rc == -1) { perror("Error in DISCSIGNAL ioctl"); return 1; } printf("Waiting for usb disconnect\n"); while (!done) { sleep(1); } close(fd); return 0; } Cc: Greg Kroah-Hartman Cc: linux-usb@vger.kernel.org Cc: Alan Stern Cc: Oliver Neukum Fixes: v2.3.39 Cc: stable@vger.kernel.org Acked-by: Alan Stern Signed-off-by: "Eric W. Biederman" --- drivers/usb/core/devio.c | 48 ++++++++++++++++++++++++------------------------ 1 file changed, 24 insertions(+), 24 deletions(-) (limited to 'drivers/usb') diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index fa783531ee88..a02448105527 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -63,7 +63,7 @@ struct usb_dev_state { unsigned int discsignr; struct pid *disc_pid; const struct cred *cred; - void __user *disccontext; + sigval_t disccontext; unsigned long ifclaimed; u32 disabled_bulk_eps; bool privileges_dropped; @@ -90,6 +90,7 @@ struct async { unsigned int ifnum; void __user *userbuffer; void __user *userurb; + sigval_t userurb_sigval; struct urb *urb; struct usb_memory *usbm; unsigned int mem_usage; @@ -582,22 +583,19 @@ static void async_completed(struct urb *urb) { struct async *as = urb->context; struct usb_dev_state *ps = as->ps; - struct kernel_siginfo sinfo; struct pid *pid = NULL; const struct cred *cred = NULL; unsigned long flags; - int signr; + sigval_t addr; + int signr, errno; spin_lock_irqsave(&ps->lock, flags); list_move_tail(&as->asynclist, &ps->async_completed); as->status = urb->status; signr = as->signr; if (signr) { - clear_siginfo(&sinfo); - sinfo.si_signo = as->signr; - sinfo.si_errno = as->status; - sinfo.si_code = SI_ASYNCIO; - sinfo.si_addr = as->userurb; + errno = as->status; + addr = as->userurb_sigval; pid = get_pid(as->pid); cred = get_cred(as->cred); } @@ -615,7 +613,7 @@ static void async_completed(struct urb *urb) spin_unlock_irqrestore(&ps->lock, flags); if (signr) { - kill_pid_info_as_cred(sinfo.si_signo, &sinfo, pid, cred); + kill_pid_usb_asyncio(signr, errno, addr, pid, cred); put_pid(pid); put_cred(cred); } @@ -1427,7 +1425,7 @@ find_memory_area(struct usb_dev_state *ps, const struct usbdevfs_urb *uurb) static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb, struct usbdevfs_iso_packet_desc __user *iso_frame_desc, - void __user *arg) + void __user *arg, sigval_t userurb_sigval) { struct usbdevfs_iso_packet_desc *isopkt = NULL; struct usb_host_endpoint *ep; @@ -1727,6 +1725,7 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb isopkt = NULL; as->ps = ps; as->userurb = arg; + as->userurb_sigval = userurb_sigval; if (as->usbm) { unsigned long uurb_start = (unsigned long)uurb->buffer; @@ -1801,13 +1800,17 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb static int proc_submiturb(struct usb_dev_state *ps, void __user *arg) { struct usbdevfs_urb uurb; + sigval_t userurb_sigval; if (copy_from_user(&uurb, arg, sizeof(uurb))) return -EFAULT; + memset(&userurb_sigval, 0, sizeof(userurb_sigval)); + userurb_sigval.sival_ptr = arg; + return proc_do_submiturb(ps, &uurb, (((struct usbdevfs_urb __user *)arg)->iso_frame_desc), - arg); + arg, userurb_sigval); } static int proc_unlinkurb(struct usb_dev_state *ps, void __user *arg) @@ -1977,7 +1980,7 @@ static int proc_disconnectsignal_compat(struct usb_dev_state *ps, void __user *a if (copy_from_user(&ds, arg, sizeof(ds))) return -EFAULT; ps->discsignr = ds.signr; - ps->disccontext = compat_ptr(ds.context); + ps->disccontext.sival_int = ds.context; return 0; } @@ -2005,13 +2008,17 @@ static int get_urb32(struct usbdevfs_urb *kurb, static int proc_submiturb_compat(struct usb_dev_state *ps, void __user *arg) { struct usbdevfs_urb uurb; + sigval_t userurb_sigval; if (get_urb32(&uurb, (struct usbdevfs_urb32 __user *)arg)) return -EFAULT; + memset(&userurb_sigval, 0, sizeof(userurb_sigval)); + userurb_sigval.sival_int = ptr_to_compat(arg); + return proc_do_submiturb(ps, &uurb, ((struct usbdevfs_urb32 __user *)arg)->iso_frame_desc, - arg); + arg, userurb_sigval); } static int processcompl_compat(struct async *as, void __user * __user *arg) @@ -2092,7 +2099,7 @@ static int proc_disconnectsignal(struct usb_dev_state *ps, void __user *arg) if (copy_from_user(&ds, arg, sizeof(ds))) return -EFAULT; ps->discsignr = ds.signr; - ps->disccontext = ds.context; + ps->disccontext.sival_ptr = ds.context; return 0; } @@ -2614,22 +2621,15 @@ const struct file_operations usbdev_file_operations = { static void usbdev_remove(struct usb_device *udev) { struct usb_dev_state *ps; - struct kernel_siginfo sinfo; while (!list_empty(&udev->filelist)) { ps = list_entry(udev->filelist.next, struct usb_dev_state, list); destroy_all_async(ps); wake_up_all(&ps->wait); list_del_init(&ps->list); - if (ps->discsignr) { - clear_siginfo(&sinfo); - sinfo.si_signo = ps->discsignr; - sinfo.si_errno = EPIPE; - sinfo.si_code = SI_ASYNCIO; - sinfo.si_addr = ps->disccontext; - kill_pid_info_as_cred(ps->discsignr, &sinfo, - ps->disc_pid, ps->cred); - } + if (ps->discsignr) + kill_pid_usb_asyncio(ps->discsignr, EPIPE, ps->disccontext, + ps->disc_pid, ps->cred); } } -- cgit v1.2.3