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authorLinus Torvalds <torvalds@linux-foundation.org>2020-10-12 16:35:51 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-10-12 16:35:51 -0700
commit85ed13e78dbedf9433115a62c85429922bc5035c (patch)
tree159866fd4d89b3c125a8627bd5153b739d4059c1 /lib
parentc90578360c92c71189308ebc71087197080e94c3 (diff)
parent5d47b394794d3086c1c338cc014011a9ee34005c (diff)
Merge branch 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull compat iovec cleanups from Al Viro: "Christoph's series around import_iovec() and compat variant thereof" * 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: security/keys: remove compat_keyctl_instantiate_key_iov mm: remove compat_process_vm_{readv,writev} fs: remove compat_sys_vmsplice fs: remove the compat readv/writev syscalls fs: remove various compat readv/writev helpers iov_iter: transparently handle compat iovecs in import_iovec iov_iter: refactor rw_copy_check_uvector and import_iovec iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c compat.h: fix a spelling error in <linux/compat.h>
Diffstat (limited to 'lib')
-rw-r--r--lib/iov_iter.c178
1 files changed, 136 insertions, 42 deletions
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 6351b211c92d..14cae2584db4 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -7,6 +7,7 @@
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/splice.h>
+#include <linux/compat.h>
#include <net/checksum.h>
#include <linux/scatterlist.h>
#include <linux/instrumented.h>
@@ -1645,16 +1646,145 @@ const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
}
EXPORT_SYMBOL(dup_iter);
+static int copy_compat_iovec_from_user(struct iovec *iov,
+ const struct iovec __user *uvec, unsigned long nr_segs)
+{
+ const struct compat_iovec __user *uiov =
+ (const struct compat_iovec __user *)uvec;
+ int ret = -EFAULT, i;
+
+ if (!user_access_begin(uvec, nr_segs * sizeof(*uvec)))
+ return -EFAULT;
+
+ for (i = 0; i < nr_segs; i++) {
+ compat_uptr_t buf;
+ compat_ssize_t len;
+
+ unsafe_get_user(len, &uiov[i].iov_len, uaccess_end);
+ unsafe_get_user(buf, &uiov[i].iov_base, uaccess_end);
+
+ /* check for compat_size_t not fitting in compat_ssize_t .. */
+ if (len < 0) {
+ ret = -EINVAL;
+ goto uaccess_end;
+ }
+ iov[i].iov_base = compat_ptr(buf);
+ iov[i].iov_len = len;
+ }
+
+ ret = 0;
+uaccess_end:
+ user_access_end();
+ return ret;
+}
+
+static int copy_iovec_from_user(struct iovec *iov,
+ const struct iovec __user *uvec, unsigned long nr_segs)
+{
+ unsigned long seg;
+
+ if (copy_from_user(iov, uvec, nr_segs * sizeof(*uvec)))
+ return -EFAULT;
+ for (seg = 0; seg < nr_segs; seg++) {
+ if ((ssize_t)iov[seg].iov_len < 0)
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+struct iovec *iovec_from_user(const struct iovec __user *uvec,
+ unsigned long nr_segs, unsigned long fast_segs,
+ struct iovec *fast_iov, bool compat)
+{
+ struct iovec *iov = fast_iov;
+ int ret;
+
+ /*
+ * 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)
+ return iov;
+ if (nr_segs > UIO_MAXIOV)
+ return ERR_PTR(-EINVAL);
+ if (nr_segs > fast_segs) {
+ iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL);
+ if (!iov)
+ return ERR_PTR(-ENOMEM);
+ }
+
+ if (compat)
+ ret = copy_compat_iovec_from_user(iov, uvec, nr_segs);
+ else
+ ret = copy_iovec_from_user(iov, uvec, nr_segs);
+ if (ret) {
+ if (iov != fast_iov)
+ kfree(iov);
+ return ERR_PTR(ret);
+ }
+
+ return iov;
+}
+
+ssize_t __import_iovec(int type, const struct iovec __user *uvec,
+ unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
+ struct iov_iter *i, bool compat)
+{
+ ssize_t total_len = 0;
+ unsigned long seg;
+ struct iovec *iov;
+
+ iov = iovec_from_user(uvec, nr_segs, fast_segs, *iovp, compat);
+ if (IS_ERR(iov)) {
+ *iovp = NULL;
+ return PTR_ERR(iov);
+ }
+
+ /*
+ * 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.
+ */
+ for (seg = 0; seg < nr_segs; seg++) {
+ ssize_t len = (ssize_t)iov[seg].iov_len;
+
+ if (!access_ok(iov[seg].iov_base, len)) {
+ if (iov != *iovp)
+ kfree(iov);
+ *iovp = NULL;
+ return -EFAULT;
+ }
+
+ if (len > MAX_RW_COUNT - total_len) {
+ len = MAX_RW_COUNT - total_len;
+ iov[seg].iov_len = len;
+ }
+ total_len += len;
+ }
+
+ iov_iter_init(i, type, iov, nr_segs, total_len);
+ if (iov == *iovp)
+ *iovp = NULL;
+ else
+ *iovp = iov;
+ return total_len;
+}
+
/**
* import_iovec() - Copy an array of &struct iovec from userspace
* into the kernel, check that it is valid, and initialize a new
* &struct iov_iter iterator to access it.
*
* @type: One of %READ or %WRITE.
- * @uvector: Pointer to the userspace array.
+ * @uvec: Pointer to the userspace array.
* @nr_segs: Number of elements in userspace array.
* @fast_segs: Number of elements in @iov.
- * @iov: (input and output parameter) Pointer to pointer to (usually small
+ * @iovp: (input and output parameter) Pointer to pointer to (usually small
* on-stack) kernel array.
* @i: Pointer to iterator that will be initialized on success.
*
@@ -1667,51 +1797,15 @@ EXPORT_SYMBOL(dup_iter);
*
* Return: Negative error code on error, bytes imported on success
*/
-ssize_t import_iovec(int type, const struct iovec __user * uvector,
+ssize_t import_iovec(int type, const struct iovec __user *uvec,
unsigned nr_segs, unsigned fast_segs,
- struct iovec **iov, struct iov_iter *i)
+ struct iovec **iovp, struct iov_iter *i)
{
- ssize_t n;
- struct iovec *p;
- n = rw_copy_check_uvector(type, uvector, nr_segs, fast_segs,
- *iov, &p);
- if (n < 0) {
- if (p != *iov)
- kfree(p);
- *iov = NULL;
- return n;
- }
- iov_iter_init(i, type, p, nr_segs, n);
- *iov = p == *iov ? NULL : p;
- return n;
+ return __import_iovec(type, uvec, nr_segs, fast_segs, iovp, i,
+ in_compat_syscall());
}
EXPORT_SYMBOL(import_iovec);
-#ifdef CONFIG_COMPAT
-#include <linux/compat.h>
-
-ssize_t compat_import_iovec(int type,
- const struct compat_iovec __user * uvector,
- unsigned nr_segs, unsigned fast_segs,
- struct iovec **iov, struct iov_iter *i)
-{
- ssize_t n;
- struct iovec *p;
- n = compat_rw_copy_check_uvector(type, uvector, nr_segs, fast_segs,
- *iov, &p);
- if (n < 0) {
- if (p != *iov)
- kfree(p);
- *iov = NULL;
- return n;
- }
- iov_iter_init(i, type, p, nr_segs, n);
- *iov = p == *iov ? NULL : p;
- return n;
-}
-EXPORT_SYMBOL(compat_import_iovec);
-#endif
-
int import_single_range(int rw, void __user *buf, size_t len,
struct iovec *iov, struct iov_iter *i)
{