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authorKees Cook <keescook@chromium.org>2020-08-11 18:36:30 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-08-12 10:58:01 -0700
commit0fd338b2d2cdf827091ae819ae90ad760b94ad0c (patch)
tree1676646361377dc5f10c7dfb56044dc44d991293 /fs/exec.c
parent633fb6ac39801514613fbe050db6abdc3fe744d5 (diff)
exec: move path_noexec() check earlier
The path_noexec() check, like the regular file check, was happening too late, letting LSMs see impossible execve()s. Check it earlier as well in may_open() and collect the redundant fs/exec.c path_noexec() test under the same robustness comment as the S_ISREG() check. My notes on the call path, and related arguments, checks, etc: do_open_execat() struct open_flags open_exec_flags = { .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, .acc_mode = MAY_EXEC, ... do_filp_open(dfd, filename, open_flags) path_openat(nameidata, open_flags, flags) file = alloc_empty_file(open_flags, current_cred()); do_open(nameidata, file, open_flags) may_open(path, acc_mode, open_flag) /* new location of MAY_EXEC vs path_noexec() test */ inode_permission(inode, MAY_OPEN | acc_mode) security_inode_permission(inode, acc_mode) vfs_open(path, file) do_dentry_open(file, path->dentry->d_inode, open) security_file_open(f) open() /* old location of path_noexec() test */ Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Aleksa Sarai <cyphar@cyphar.com> Cc: Christian Brauner <christian.brauner@ubuntu.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Eric Biggers <ebiggers3@gmail.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Link: http://lkml.kernel.org/r/20200605160013.3954297-4-keescook@chromium.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/exec.c')
-rw-r--r--fs/exec.c12
1 files changed, 4 insertions, 8 deletions
diff --git a/fs/exec.c b/fs/exec.c
index cc7ec7b9000b..a57d9785832b 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -147,10 +147,8 @@ SYSCALL_DEFINE1(uselib, const char __user *, library)
* and check again at the very end too.
*/
error = -EACCES;
- if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode)))
- goto exit;
-
- if (path_noexec(&file->f_path))
+ if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) ||
+ path_noexec(&file->f_path)))
goto exit;
fsnotify_open(file);
@@ -919,10 +917,8 @@ static struct file *do_open_execat(int fd, struct filename *name, int flags)
* and check again at the very end too.
*/
err = -EACCES;
- if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode)))
- goto exit;
-
- if (path_noexec(&file->f_path))
+ if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) ||
+ path_noexec(&file->f_path)))
goto exit;
err = deny_write_access(file);