[2/9] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c

Message ID	20200925045146.1283714-3-hch@lst.de (mailing list archive)
State	New, archived
Headers	show Return-Path: <SRS0=6XiI=DC=vger.kernel.org=linux-security-module-owner@kernel.org> From: Christoph Hellwig <hch@lst.de> To: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org>, Jens Axboe <axboe@kernel.dk>, Arnd Bergmann <arnd@arndb.de>, David Howells <dhowells@redhat.com>, David Laight <David.Laight@aculab.com>, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, io-uring@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, keyrings@vger.kernel.org, linux-security-module@vger.kernel.org, David Laight <David.Laight@ACULAB.COM>, David Laight <david.laight@aculab.com> Subject: [PATCH 2/9] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c Date: Fri, 25 Sep 2020 06:51:39 +0200 Message-Id: <20200925045146.1283714-3-hch@lst.de> In-Reply-To: <20200925045146.1283714-1-hch@lst.de> References: <20200925045146.1283714-1-hch@lst.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	[1/9] compat.h: fix a spelling error in <linux/compat.h> \| expand [1/9] compat.h: fix a spelling error in <linux/compat.h> [2/9] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c [3/9] iov_iter: refactor rw_copy_check_uvector and import_iovec [4/9] iov_iter: transparently handle compat iovecs in import_iovec [5/9] fs: remove various compat readv/writev helpers [6/9] fs: remove the compat readv/writev syscalls [7/9] fs: remove compat_sys_vmsplice [8/9] mm: remove compat_process_vm_{readv,writev} [9/9] security/keys: remove compat_keyctl_instantiate_key_iov

diff --git a/fs/read_write.c b/fs/read_write.c index 5db58b8c78d0dd..e5e891a88442ef 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -752,185 +752,6 @@ static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter, return ret; } -/** - * rw_copy_check_uvector() - Copy an array of &struct iovec from userspace - * into the kernel and check that it is valid. - * - * @type: One of %CHECK_IOVEC_ONLY, %READ, or %WRITE. - * @uvector: Pointer to the userspace array. - * @nr_segs: Number of elements in userspace array. - * @fast_segs: Number of elements in @fast_pointer. - * @fast_pointer: Pointer to (usually small on-stack) kernel array. - * @ret_pointer: (output parameter) Pointer to a variable that will point to - * either @fast_pointer, a newly allocated kernel array, or NULL, - * depending on which array was used. - * - * This function copies an array of &struct iovec of @nr_segs from - * userspace into the kernel and checks that each element is valid (e.g. - * it does not point to a kernel address or cause overflow by being too - * large, etc.). - * - * As an optimization, the caller may provide a pointer to a small - * on-stack array in @fast_pointer, typically %UIO_FASTIOV elements long - * (the size of this array, or 0 if unused, should be given in @fast_segs). - * - * @ret_pointer will always point to the array that was used, so the - * caller must take care not to call kfree() on it e.g. in case the - * @fast_pointer array was used and it was allocated on the stack. - * - * Return: The total number of bytes covered by the iovec array on success - * or a negative error code on error. - */ -ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector, - unsigned long nr_segs, unsigned long fast_segs, - struct iovec *fast_pointer, - struct iovec **ret_pointer) -{ - unsigned long seg; - ssize_t ret; - struct iovec *iov = fast_pointer; - - /* - * SuS says "The readv() function *may* fail if the iovcnt argument - * was less than or equal to 0, or greater than {IOV_MAX}. Linux has - * traditionally returned zero for zero segments, so... - */ - if (nr_segs == 0) { - ret = 0; - goto out; - } - - /* - * First get the "struct iovec" from user memory and - * verify all the pointers - */ - if (nr_segs > UIO_MAXIOV) { - ret = -EINVAL; - goto out; - } - if (nr_segs > fast_segs) { - iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL); - if (iov == NULL) { - ret = -ENOMEM; - goto out; - } - } - if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector))) { - ret = -EFAULT; - goto out; - } - - /* - * According to the Single Unix Specification we should return EINVAL - * if an element length is < 0 when cast to ssize_t or if the - * total length would overflow the ssize_t return value of the - * system call. - * - * Linux caps all read/write calls to MAX_RW_COUNT, and avoids the - * overflow case. - */ - ret = 0; - for (seg = 0; seg < nr_segs; seg++) { - void __user *buf = iov[seg].iov_base; - ssize_t len = (ssize_t)iov[seg].iov_len; - - /* see if we we're about to use an invalid len or if - * it's about to overflow ssize_t */ - if (len < 0) { - ret = -EINVAL; - goto out; - } - if (type >= 0 - && unlikely(!access_ok(buf, len))) { - ret = -EFAULT; - goto out; - } - if (len > MAX_RW_COUNT - ret) { - len = MAX_RW_COUNT - ret; - iov[seg].iov_len = len; - } - ret += len; - } -out: - *ret_pointer = iov; - return ret; -} - -#ifdef CONFIG_COMPAT -ssize_t compat_rw_copy_check_uvector(int type, - const struct compat_iovec __user *uvector, unsigned long nr_segs, - unsigned long fast_segs, struct iovec *fast_pointer, - struct iovec **ret_pointer) -{ - compat_ssize_t tot_len; - struct iovec *iov = *ret_pointer = fast_pointer; - ssize_t ret = 0; - int seg; - - /* - * SuS says "The readv() function *may* fail if the iovcnt argument - * was less than or equal to 0, or greater than {IOV_MAX}. Linux has - * traditionally returned zero for zero segments, so... - */ - if (nr_segs == 0) - goto out; - - ret = -EINVAL; - if (nr_segs > UIO_MAXIOV) - goto out; - if (nr_segs > fast_segs) { - ret = -ENOMEM; - iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL); - if (iov == NULL) - goto out; - } - *ret_pointer = iov; - - ret = -EFAULT; - if (!access_ok(uvector, nr_segs*sizeof(*uvector))) - goto out; - - /* - * Single unix specification: - * We should -EINVAL if an element length is not >= 0 and fitting an - * ssize_t. - * - * In Linux, the total length is limited to MAX_RW_COUNT, there is - * no overflow possibility. - */ - tot_len = 0; - ret = -EINVAL; - for (seg = 0; seg < nr_segs; seg++) { - compat_uptr_t buf; - compat_ssize_t len; - - if (__get_user(len, &uvector->iov_len) || - __get_user(buf, &uvector->iov_base)) { - ret = -EFAULT; - goto out; - } - if (len < 0) /* size_t not fitting in compat_ssize_t .. */ - goto out; - if (type >= 0 && - !access_ok(compat_ptr(buf), len)) { - ret = -EFAULT; - goto out; - } - if (len > MAX_RW_COUNT - tot_len) - len = MAX_RW_COUNT - tot_len; - tot_len += len; - iov->iov_base = compat_ptr(buf); - iov->iov_len = (compat_size_t) len; - uvector++; - iov++; - } - ret = tot_len; - -out: - return ret; -} -#endif - static ssize_t do_iter_read(struct file *file, struct iov_iter *iter, loff_t *pos, rwf_t flags) { diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 5e40786c8f1232..ccea9db3f72be8 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -1650,6 +1650,109 @@ const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags) } EXPORT_SYMBOL(dup_iter); +/** + * rw_copy_check_uvector() - Copy an array of &struct iovec from userspace + * into the kernel and check that it is valid. + * + * @type: One of %CHECK_IOVEC_ONLY, %READ, or %WRITE. + * @uvector: Pointer to the userspace array. + * @nr_segs: Number of elements in userspace array. + * @fast_segs: Number of elements in @fast_pointer. + * @fast_pointer: Pointer to (usually small on-stack) kernel array. + * @ret_pointer: (output parameter) Pointer to a variable that will point to + * either @fast_pointer, a newly allocated kernel array, or NULL, + * depending on which array was used. + * + * This function copies an array of &struct iovec of @nr_segs from + * userspace into the kernel and checks that each element is valid (e.g. + * it does not point to a kernel address or cause overflow by being too + * large, etc.). + * + * As an optimization, the caller may provide a pointer to a small + * on-stack array in @fast_pointer, typically %UIO_FASTIOV elements long + * (the size of this array, or 0 if unused, should be given in @fast_segs). + * + * @ret_pointer will always point to the array that was used, so the + * caller must take care not to call kfree() on it e.g. in case the + * @fast_pointer array was used and it was allocated on the stack. + * + * Return: The total number of bytes covered by the iovec array on success + * or a negative error code on error. + */ +ssize_t rw_copy_check_uvector(int type, const struct iovec __user *uvector, + unsigned long nr_segs, unsigned long fast_segs, + struct iovec *fast_pointer, struct iovec **ret_pointer) +{ + unsigned long seg; + ssize_t ret; + struct iovec *iov = fast_pointer; + + /* + * SuS says "The readv() function *may* fail if the iovcnt argument + * was less than or equal to 0, or greater than {IOV_MAX}. Linux has + * traditionally returned zero for zero segments, so... + */ + if (nr_segs == 0) { + ret = 0; + goto out; + } + + /* + * First get the "struct iovec" from user memory and + * verify all the pointers + */ + if (nr_segs > UIO_MAXIOV) { + ret = -EINVAL; + goto out; + } + if (nr_segs > fast_segs) { + iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL); + if (iov == NULL) { + ret = -ENOMEM; + goto out; + } + } + if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector))) { + ret = -EFAULT; + goto out; + } + + /* + * According to the Single Unix Specification we should return EINVAL + * if an element length is < 0 when cast to ssize_t or if the + * total length would overflow the ssize_t return value of the + * system call. + * + * Linux caps all read/write calls to MAX_RW_COUNT, and avoids the + * overflow case. + */ + ret = 0; + for (seg = 0; seg < nr_segs; seg++) { + void __user *buf = iov[seg].iov_base; + ssize_t len = (ssize_t)iov[seg].iov_len; + + /* see if we we're about to use an invalid len or if + * it's about to overflow ssize_t */ + if (len < 0) { + ret = -EINVAL; + goto out; + } + if (type >= 0 + && unlikely(!access_ok(buf, len))) { + ret = -EFAULT; + goto out; + } + if (len > MAX_RW_COUNT - ret) { + len = MAX_RW_COUNT - ret; + iov[seg].iov_len = len; + } + ret += len; + } +out: + *ret_pointer = iov; + return ret; +} + /** * import_iovec() - Copy an array of &struct iovec from userspace * into the kernel, check that it is valid, and initialize a new @@ -1695,6 +1798,79 @@ EXPORT_SYMBOL(import_iovec); #ifdef CONFIG_COMPAT #include <linux/compat.h> +ssize_t compat_rw_copy_check_uvector(int type, + const struct compat_iovec __user *uvector, + unsigned long nr_segs, unsigned long fast_segs, + struct iovec *fast_pointer, struct iovec **ret_pointer) +{ + compat_ssize_t tot_len; + struct iovec *iov = *ret_pointer = fast_pointer; + ssize_t ret = 0; + int seg; + + /* + * SuS says "The readv() function *may* fail if the iovcnt argument + * was less than or equal to 0, or greater than {IOV_MAX}. Linux has + * traditionally returned zero for zero segments, so... + */ + if (nr_segs == 0) + goto out; + + ret = -EINVAL; + if (nr_segs > UIO_MAXIOV) + goto out; + if (nr_segs > fast_segs) { + ret = -ENOMEM; + iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL); + if (iov == NULL) + goto out; + } + *ret_pointer = iov; + + ret = -EFAULT; + if (!access_ok(uvector, nr_segs*sizeof(*uvector))) + goto out; + + /* + * Single unix specification: + * We should -EINVAL if an element length is not >= 0 and fitting an + * ssize_t. + * + * In Linux, the total length is limited to MAX_RW_COUNT, there is + * no overflow possibility. + */ + tot_len = 0; + ret = -EINVAL; + for (seg = 0; seg < nr_segs; seg++) { + compat_uptr_t buf; + compat_ssize_t len; + + if (__get_user(len, &uvector->iov_len) || + __get_user(buf, &uvector->iov_base)) { + ret = -EFAULT; + goto out; + } + if (len < 0) /* size_t not fitting in compat_ssize_t .. */ + goto out; + if (type >= 0 && + !access_ok(compat_ptr(buf), len)) { + ret = -EFAULT; + goto out; + } + if (len > MAX_RW_COUNT - tot_len) + len = MAX_RW_COUNT - tot_len; + tot_len += len; + iov->iov_base = compat_ptr(buf); + iov->iov_len = (compat_size_t) len; + uvector++; + iov++; + } + ret = tot_len; + +out: + return ret; +} + ssize_t compat_import_iovec(int type, const struct compat_iovec __user * uvector, unsigned nr_segs, unsigned fast_segs,

[2/9] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c

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