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authorChristoph Hellwig <hch@lst.de>2020-06-04 16:51:18 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-04 19:06:26 -0700
commit762a3af6faa0682e5b30b67b1db156c7df55f2c7 (patch)
tree0839d8bacabd03afe329facc4b119814840a82bb /fs/exec.c
parent986db2d14a6dca6456b63b4f5c410ae2aab4ec9d (diff)
downloadlinux-762a3af6faa0682e5b30b67b1db156c7df55f2c7.tar.bz2
exec: open code copy_string_kernel
Currently copy_string_kernel is just a wrapper around copy_strings that simplifies the calling conventions and uses set_fs to allow passing a kernel pointer. But due to the fact the we only need to handle a single kernel argument pointer, the logic can be sigificantly simplified while getting rid of the set_fs. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Link: http://lkml.kernel.org/r/20200501104105.2621149-3-hch@lst.de Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/exec.c')
-rw-r--r--fs/exec.c43
1 files changed, 34 insertions, 9 deletions
diff --git a/fs/exec.c b/fs/exec.c
index 4814b26a56fb..03a85e3c49bb 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -592,17 +592,42 @@ out:
*/
int copy_string_kernel(const char *arg, struct linux_binprm *bprm)
{
- int r;
- mm_segment_t oldfs = get_fs();
- struct user_arg_ptr argv = {
- .ptr.native = (const char __user *const __user *)&arg,
- };
+ int len = strnlen(arg, MAX_ARG_STRLEN) + 1 /* terminating NUL */;
+ unsigned long pos = bprm->p;
+
+ if (len == 0)
+ return -EFAULT;
+ if (!valid_arg_len(bprm, len))
+ return -E2BIG;
+
+ /* We're going to work our way backwards. */
+ arg += len;
+ bprm->p -= len;
+ if (IS_ENABLED(CONFIG_MMU) && bprm->p < bprm->argmin)
+ return -E2BIG;
+
+ while (len > 0) {
+ unsigned int bytes_to_copy = min_t(unsigned int, len,
+ min_not_zero(offset_in_page(pos), PAGE_SIZE));
+ struct page *page;
+ char *kaddr;
- set_fs(KERNEL_DS);
- r = copy_strings(1, argv, bprm);
- set_fs(oldfs);
+ pos -= bytes_to_copy;
+ arg -= bytes_to_copy;
+ len -= bytes_to_copy;
- return r;
+ page = get_arg_page(bprm, pos, 1);
+ if (!page)
+ return -E2BIG;
+ kaddr = kmap_atomic(page);
+ flush_arg_page(bprm, pos & PAGE_MASK, page);
+ memcpy(kaddr + offset_in_page(pos), arg, bytes_to_copy);
+ flush_kernel_dcache_page(page);
+ kunmap_atomic(kaddr);
+ put_arg_page(page);
+ }
+
+ return 0;
}
EXPORT_SYMBOL(copy_string_kernel);