iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c
This lets the compiler inline it into import_iovec() generating much better code. Signed-off-by: David Laight <david.laight@aculab.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
David Laight
Al Viro
parent
576d0703a8
commit
fb041b5989
179
fs/read_write.c
179
fs/read_write.c
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@ -752,185 +752,6 @@ static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter,
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return ret;
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}
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/**
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* rw_copy_check_uvector() - Copy an array of &struct iovec from userspace
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* into the kernel and check that it is valid.
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*
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* @type: One of %CHECK_IOVEC_ONLY, %READ, or %WRITE.
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* @uvector: Pointer to the userspace array.
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* @nr_segs: Number of elements in userspace array.
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* @fast_segs: Number of elements in @fast_pointer.
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* @fast_pointer: Pointer to (usually small on-stack) kernel array.
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* @ret_pointer: (output parameter) Pointer to a variable that will point to
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* either @fast_pointer, a newly allocated kernel array, or NULL,
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* depending on which array was used.
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*
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* This function copies an array of &struct iovec of @nr_segs from
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* userspace into the kernel and checks that each element is valid (e.g.
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* it does not point to a kernel address or cause overflow by being too
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* large, etc.).
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*
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* As an optimization, the caller may provide a pointer to a small
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* on-stack array in @fast_pointer, typically %UIO_FASTIOV elements long
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* (the size of this array, or 0 if unused, should be given in @fast_segs).
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*
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* @ret_pointer will always point to the array that was used, so the
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* caller must take care not to call kfree() on it e.g. in case the
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* @fast_pointer array was used and it was allocated on the stack.
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*
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* Return: The total number of bytes covered by the iovec array on success
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* or a negative error code on error.
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*/
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ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
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unsigned long nr_segs, unsigned long fast_segs,
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struct iovec *fast_pointer,
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struct iovec **ret_pointer)
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{
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unsigned long seg;
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ssize_t ret;
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struct iovec *iov = fast_pointer;
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/*
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* SuS says "The readv() function *may* fail if the iovcnt argument
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* was less than or equal to 0, or greater than {IOV_MAX}. Linux has
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* traditionally returned zero for zero segments, so...
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*/
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if (nr_segs == 0) {
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ret = 0;
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goto out;
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}
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/*
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* First get the "struct iovec" from user memory and
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* verify all the pointers
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*/
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if (nr_segs > UIO_MAXIOV) {
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ret = -EINVAL;
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goto out;
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}
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if (nr_segs > fast_segs) {
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iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL);
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if (iov == NULL) {
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ret = -ENOMEM;
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goto out;
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}
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}
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if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector))) {
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ret = -EFAULT;
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goto out;
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}
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/*
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* According to the Single Unix Specification we should return EINVAL
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* if an element length is < 0 when cast to ssize_t or if the
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* total length would overflow the ssize_t return value of the
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* system call.
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*
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* Linux caps all read/write calls to MAX_RW_COUNT, and avoids the
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* overflow case.
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*/
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ret = 0;
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for (seg = 0; seg < nr_segs; seg++) {
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void __user *buf = iov[seg].iov_base;
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ssize_t len = (ssize_t)iov[seg].iov_len;
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/* see if we we're about to use an invalid len or if
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* it's about to overflow ssize_t */
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if (len < 0) {
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ret = -EINVAL;
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goto out;
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}
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if (type >= 0
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&& unlikely(!access_ok(buf, len))) {
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ret = -EFAULT;
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goto out;
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}
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if (len > MAX_RW_COUNT - ret) {
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len = MAX_RW_COUNT - ret;
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iov[seg].iov_len = len;
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}
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ret += len;
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}
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out:
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*ret_pointer = iov;
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return ret;
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}
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#ifdef CONFIG_COMPAT
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ssize_t compat_rw_copy_check_uvector(int type,
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const struct compat_iovec __user *uvector, unsigned long nr_segs,
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unsigned long fast_segs, struct iovec *fast_pointer,
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struct iovec **ret_pointer)
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{
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compat_ssize_t tot_len;
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struct iovec *iov = *ret_pointer = fast_pointer;
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ssize_t ret = 0;
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int seg;
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/*
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* SuS says "The readv() function *may* fail if the iovcnt argument
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* was less than or equal to 0, or greater than {IOV_MAX}. Linux has
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* traditionally returned zero for zero segments, so...
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*/
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if (nr_segs == 0)
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goto out;
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ret = -EINVAL;
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if (nr_segs > UIO_MAXIOV)
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goto out;
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if (nr_segs > fast_segs) {
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ret = -ENOMEM;
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iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL);
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if (iov == NULL)
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goto out;
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}
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*ret_pointer = iov;
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ret = -EFAULT;
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if (!access_ok(uvector, nr_segs*sizeof(*uvector)))
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goto out;
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/*
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* Single unix specification:
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* We should -EINVAL if an element length is not >= 0 and fitting an
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* ssize_t.
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*
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* In Linux, the total length is limited to MAX_RW_COUNT, there is
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* no overflow possibility.
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*/
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tot_len = 0;
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ret = -EINVAL;
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for (seg = 0; seg < nr_segs; seg++) {
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compat_uptr_t buf;
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compat_ssize_t len;
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if (__get_user(len, &uvector->iov_len) ||
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__get_user(buf, &uvector->iov_base)) {
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ret = -EFAULT;
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goto out;
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}
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if (len < 0) /* size_t not fitting in compat_ssize_t .. */
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goto out;
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if (type >= 0 &&
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!access_ok(compat_ptr(buf), len)) {
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ret = -EFAULT;
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goto out;
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}
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if (len > MAX_RW_COUNT - tot_len)
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len = MAX_RW_COUNT - tot_len;
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tot_len += len;
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iov->iov_base = compat_ptr(buf);
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iov->iov_len = (compat_size_t) len;
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uvector++;
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iov++;
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}
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ret = tot_len;
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out:
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return ret;
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}
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#endif
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static ssize_t do_iter_read(struct file *file, struct iov_iter *iter,
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loff_t *pos, rwf_t flags)
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{
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176
lib/iov_iter.c
176
lib/iov_iter.c
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@ -1650,6 +1650,109 @@ const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
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}
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EXPORT_SYMBOL(dup_iter);
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/**
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* rw_copy_check_uvector() - Copy an array of &struct iovec from userspace
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* into the kernel and check that it is valid.
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*
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* @type: One of %CHECK_IOVEC_ONLY, %READ, or %WRITE.
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* @uvector: Pointer to the userspace array.
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* @nr_segs: Number of elements in userspace array.
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* @fast_segs: Number of elements in @fast_pointer.
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* @fast_pointer: Pointer to (usually small on-stack) kernel array.
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* @ret_pointer: (output parameter) Pointer to a variable that will point to
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* either @fast_pointer, a newly allocated kernel array, or NULL,
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* depending on which array was used.
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*
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* This function copies an array of &struct iovec of @nr_segs from
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* userspace into the kernel and checks that each element is valid (e.g.
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* it does not point to a kernel address or cause overflow by being too
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* large, etc.).
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*
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* As an optimization, the caller may provide a pointer to a small
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* on-stack array in @fast_pointer, typically %UIO_FASTIOV elements long
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* (the size of this array, or 0 if unused, should be given in @fast_segs).
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*
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* @ret_pointer will always point to the array that was used, so the
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* caller must take care not to call kfree() on it e.g. in case the
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* @fast_pointer array was used and it was allocated on the stack.
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*
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* Return: The total number of bytes covered by the iovec array on success
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* or a negative error code on error.
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*/
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ssize_t rw_copy_check_uvector(int type, const struct iovec __user *uvector,
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unsigned long nr_segs, unsigned long fast_segs,
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struct iovec *fast_pointer, struct iovec **ret_pointer)
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{
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unsigned long seg;
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ssize_t ret;
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struct iovec *iov = fast_pointer;
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/*
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* SuS says "The readv() function *may* fail if the iovcnt argument
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* was less than or equal to 0, or greater than {IOV_MAX}. Linux has
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* traditionally returned zero for zero segments, so...
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*/
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if (nr_segs == 0) {
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ret = 0;
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goto out;
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}
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/*
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* First get the "struct iovec" from user memory and
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* verify all the pointers
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*/
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if (nr_segs > UIO_MAXIOV) {
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ret = -EINVAL;
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goto out;
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}
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if (nr_segs > fast_segs) {
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iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL);
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if (iov == NULL) {
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ret = -ENOMEM;
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goto out;
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}
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}
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if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector))) {
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ret = -EFAULT;
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goto out;
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}
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/*
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* According to the Single Unix Specification we should return EINVAL
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* if an element length is < 0 when cast to ssize_t or if the
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* total length would overflow the ssize_t return value of the
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* system call.
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*
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* Linux caps all read/write calls to MAX_RW_COUNT, and avoids the
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* overflow case.
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*/
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ret = 0;
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for (seg = 0; seg < nr_segs; seg++) {
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void __user *buf = iov[seg].iov_base;
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ssize_t len = (ssize_t)iov[seg].iov_len;
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/* see if we we're about to use an invalid len or if
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* it's about to overflow ssize_t */
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if (len < 0) {
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ret = -EINVAL;
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goto out;
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}
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if (type >= 0
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&& unlikely(!access_ok(buf, len))) {
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ret = -EFAULT;
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goto out;
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}
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if (len > MAX_RW_COUNT - ret) {
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len = MAX_RW_COUNT - ret;
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iov[seg].iov_len = len;
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}
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ret += len;
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}
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out:
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*ret_pointer = iov;
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return ret;
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}
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/**
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* import_iovec() - Copy an array of &struct iovec from userspace
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* into the kernel, check that it is valid, and initialize a new
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@ -1695,6 +1798,79 @@ EXPORT_SYMBOL(import_iovec);
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#ifdef CONFIG_COMPAT
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#include <linux/compat.h>
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ssize_t compat_rw_copy_check_uvector(int type,
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const struct compat_iovec __user *uvector,
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unsigned long nr_segs, unsigned long fast_segs,
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struct iovec *fast_pointer, struct iovec **ret_pointer)
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{
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compat_ssize_t tot_len;
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struct iovec *iov = *ret_pointer = fast_pointer;
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ssize_t ret = 0;
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int seg;
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/*
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* SuS says "The readv() function *may* fail if the iovcnt argument
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* was less than or equal to 0, or greater than {IOV_MAX}. Linux has
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* traditionally returned zero for zero segments, so...
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*/
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if (nr_segs == 0)
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goto out;
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ret = -EINVAL;
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if (nr_segs > UIO_MAXIOV)
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goto out;
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if (nr_segs > fast_segs) {
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ret = -ENOMEM;
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iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL);
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if (iov == NULL)
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goto out;
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}
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*ret_pointer = iov;
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ret = -EFAULT;
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if (!access_ok(uvector, nr_segs*sizeof(*uvector)))
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goto out;
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/*
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* Single unix specification:
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* We should -EINVAL if an element length is not >= 0 and fitting an
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* ssize_t.
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*
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* In Linux, the total length is limited to MAX_RW_COUNT, there is
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* no overflow possibility.
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*/
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tot_len = 0;
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ret = -EINVAL;
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for (seg = 0; seg < nr_segs; seg++) {
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compat_uptr_t buf;
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compat_ssize_t len;
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if (__get_user(len, &uvector->iov_len) ||
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__get_user(buf, &uvector->iov_base)) {
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ret = -EFAULT;
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goto out;
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}
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if (len < 0) /* size_t not fitting in compat_ssize_t .. */
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goto out;
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if (type >= 0 &&
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!access_ok(compat_ptr(buf), len)) {
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ret = -EFAULT;
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goto out;
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}
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if (len > MAX_RW_COUNT - tot_len)
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len = MAX_RW_COUNT - tot_len;
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tot_len += len;
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iov->iov_base = compat_ptr(buf);
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iov->iov_len = (compat_size_t) len;
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uvector++;
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iov++;
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}
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ret = tot_len;
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out:
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return ret;
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}
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ssize_t compat_import_iovec(int type,
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const struct compat_iovec __user * uvector,
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unsigned nr_segs, unsigned fast_segs,
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