From 30d4b180e20c081f435143f8bc211c66a930608a Mon Sep 17 00:00:00 2001 From: Tamas Lengyel Date: Mon, 31 Dec 2012 15:44:30 -0500 Subject: xen/privcmd: Relax access control in privcmd_ioctl_mmap In the privcmd Linux driver two checks in the functions privcmd_ioctl_mmap and privcmd_ioctl_mmap_batch are not needed as they are trying to enforce hypervisor-level access control. They should be removed as they break secondary control domains when performing dom0 disaggregation. Xen itself provides adequate security controls around these hypercalls and these checks prevent those controls from functioning as intended. Signed-off-by: Tamas K Lengyel Cc: Daniel De Graaf [v1: Fixed up the patch and commit description] Signed-off-by: Konrad Rzeszutek Wilk --- drivers/xen/privcmd.c | 6 ------ 1 file changed, 6 deletions(-) (limited to 'drivers/xen/privcmd.c') diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c index b9d08987a5a5..f6316127f53f 100644 --- a/drivers/xen/privcmd.c +++ b/drivers/xen/privcmd.c @@ -199,9 +199,6 @@ static long privcmd_ioctl_mmap(void __user *udata) LIST_HEAD(pagelist); struct mmap_mfn_state state; - if (!xen_initial_domain()) - return -EPERM; - /* We only support privcmd_ioctl_mmap_batch for auto translated. */ if (xen_feature(XENFEAT_auto_translated_physmap)) return -ENOSYS; @@ -360,9 +357,6 @@ static long privcmd_ioctl_mmap_batch(void __user *udata, int version) int *err_array = NULL; struct mmap_batch_state state; - if (!xen_initial_domain()) - return -EPERM; - switch (version) { case 1: if (copy_from_user(&m, udata, sizeof(struct privcmd_mmapbatch))) -- cgit v1.2.2 From 99beae6cb8f4dd5dab81a370b79c3b1085848d89 Mon Sep 17 00:00:00 2001 From: Andres Lagar-Cavilla Date: Mon, 14 Jan 2013 22:35:40 -0500 Subject: xen/privcmd: Fix mmap batch ioctl. 1. If any individual mapping error happens, the V1 case will mark *all* operations as failed. Fixed. 2. The err_array was allocated with kcalloc, resulting in potentially O(n) page allocations. Refactor code to not use this array. Signed-off-by: Andres Lagar-Cavilla Signed-off-by: Konrad Rzeszutek Wilk --- drivers/xen/privcmd.c | 83 +++++++++++++++++++++++++++++---------------------- 1 file changed, 47 insertions(+), 36 deletions(-) (limited to 'drivers/xen/privcmd.c') diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c index 421375a9196a..ca2b00e9d558 100644 --- a/drivers/xen/privcmd.c +++ b/drivers/xen/privcmd.c @@ -258,11 +258,12 @@ struct mmap_batch_state { * -ENOENT if at least 1 -ENOENT has happened. */ int global_error; - /* An array for individual errors */ - int *err; + int version; /* User-space mfn array to store errors in the second pass for V1. */ xen_pfn_t __user *user_mfn; + /* User-space int array to store errors in the second pass for V2. */ + int __user *user_err; }; /* auto translated dom0 note: if domU being created is PV, then mfn is @@ -285,7 +286,19 @@ static int mmap_batch_fn(void *data, void *state) &cur_page); /* Store error code for second pass. */ - *(st->err++) = ret; + if (st->version == 1) { + if (ret < 0) { + /* + * V1 encodes the error codes in the 32bit top nibble of the + * mfn (with its known limitations vis-a-vis 64 bit callers). + */ + *mfnp |= (ret == -ENOENT) ? + PRIVCMD_MMAPBATCH_PAGED_ERROR : + PRIVCMD_MMAPBATCH_MFN_ERROR; + } + } else { /* st->version == 2 */ + *((int *) mfnp) = ret; + } /* And see if it affects the global_error. */ if (ret < 0) { @@ -302,20 +315,25 @@ static int mmap_batch_fn(void *data, void *state) return 0; } -static int mmap_return_errors_v1(void *data, void *state) +static int mmap_return_errors(void *data, void *state) { - xen_pfn_t *mfnp = data; struct mmap_batch_state *st = state; - int err = *(st->err++); - /* - * V1 encodes the error codes in the 32bit top nibble of the - * mfn (with its known limitations vis-a-vis 64 bit callers). - */ - *mfnp |= (err == -ENOENT) ? - PRIVCMD_MMAPBATCH_PAGED_ERROR : - PRIVCMD_MMAPBATCH_MFN_ERROR; - return __put_user(*mfnp, st->user_mfn++); + if (st->version == 1) { + xen_pfn_t mfnp = *((xen_pfn_t *) data); + if (mfnp & PRIVCMD_MMAPBATCH_MFN_ERROR) + return __put_user(mfnp, st->user_mfn++); + else + st->user_mfn++; + } else { /* st->version == 2 */ + int err = *((int *) data); + if (err) + return __put_user(err, st->user_err++); + else + st->user_err++; + } + + return 0; } /* Allocate pfns that are then mapped with gmfns from foreign domid. Update @@ -354,7 +372,6 @@ static long privcmd_ioctl_mmap_batch(void __user *udata, int version) struct vm_area_struct *vma; unsigned long nr_pages; LIST_HEAD(pagelist); - int *err_array = NULL; struct mmap_batch_state state; switch (version) { @@ -390,10 +407,12 @@ static long privcmd_ioctl_mmap_batch(void __user *udata, int version) goto out; } - err_array = kcalloc(m.num, sizeof(int), GFP_KERNEL); - if (err_array == NULL) { - ret = -ENOMEM; - goto out; + if (version == 2) { + /* Zero error array now to only copy back actual errors. */ + if (clear_user(m.err, sizeof(int) * m.num)) { + ret = -EFAULT; + goto out; + } } down_write(&mm->mmap_sem); @@ -421,7 +440,7 @@ static long privcmd_ioctl_mmap_batch(void __user *udata, int version) state.va = m.addr; state.index = 0; state.global_error = 0; - state.err = err_array; + state.version = version; /* mmap_batch_fn guarantees ret == 0 */ BUG_ON(traverse_pages(m.num, sizeof(xen_pfn_t), @@ -429,21 +448,14 @@ static long privcmd_ioctl_mmap_batch(void __user *udata, int version) up_write(&mm->mmap_sem); - if (version == 1) { - if (state.global_error) { - /* Write back errors in second pass. */ - state.user_mfn = (xen_pfn_t *)m.arr; - state.err = err_array; - ret = traverse_pages(m.num, sizeof(xen_pfn_t), - &pagelist, mmap_return_errors_v1, &state); - } else - ret = 0; - - } else if (version == 2) { - ret = __copy_to_user(m.err, err_array, m.num * sizeof(int)); - if (ret) - ret = -EFAULT; - } + if (state.global_error) { + /* Write back errors in second pass. */ + state.user_mfn = (xen_pfn_t *)m.arr; + state.user_err = m.err; + ret = traverse_pages(m.num, sizeof(xen_pfn_t), + &pagelist, mmap_return_errors, &state); + } else + ret = 0; /* If we have not had any EFAULT-like global errors then set the global * error to -ENOENT if necessary. */ @@ -451,7 +463,6 @@ static long privcmd_ioctl_mmap_batch(void __user *udata, int version) ret = -ENOENT; out: - kfree(err_array); free_page_list(&pagelist); return ret; -- cgit v1.2.2