From 986db2d14a6dca6456b63b4f5c410ae2aab4ec9d Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Thu, 4 Jun 2020 16:51:14 -0700 Subject: exec: simplify the copy_strings_kernel calling convention copy_strings_kernel is always used with a single argument, adjust the calling convention to that. Signed-off-by: Christoph Hellwig Signed-off-by: Andrew Morton Cc: Alexander Viro Link: http://lkml.kernel.org/r/20200501104105.2621149-2-hch@lst.de Signed-off-by: Linus Torvalds --- fs/exec.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) (limited to 'fs/exec.c') diff --git a/fs/exec.c b/fs/exec.c index 2c465119affc..4814b26a56fb 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -588,24 +588,23 @@ out: } /* - * Like copy_strings, but get argv and its values from kernel memory. + * Copy and argument/environment string from the kernel to the processes stack. */ -int copy_strings_kernel(int argc, const char *const *__argv, - struct linux_binprm *bprm) +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 *)__argv, + .ptr.native = (const char __user *const __user *)&arg, }; set_fs(KERNEL_DS); - r = copy_strings(argc, argv, bprm); + r = copy_strings(1, argv, bprm); set_fs(oldfs); return r; } -EXPORT_SYMBOL(copy_strings_kernel); +EXPORT_SYMBOL(copy_string_kernel); #ifdef CONFIG_MMU @@ -1865,7 +1864,7 @@ static int __do_execve_file(int fd, struct filename *filename, if (retval < 0) goto out; - retval = copy_strings_kernel(1, &bprm->filename, bprm); + retval = copy_string_kernel(bprm->filename, bprm); if (retval < 0) goto out; -- cgit v1.2.3 From 762a3af6faa0682e5b30b67b1db156c7df55f2c7 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Thu, 4 Jun 2020 16:51:18 -0700 Subject: 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 Signed-off-by: Andrew Morton Cc: Alexander Viro Link: http://lkml.kernel.org/r/20200501104105.2621149-3-hch@lst.de Signed-off-by: Linus Torvalds --- fs/exec.c | 43 ++++++++++++++++++++++++++++++++++--------- 1 file changed, 34 insertions(+), 9 deletions(-) (limited to 'fs/exec.c') 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); -- cgit v1.2.3