From: Aleksa Sarai Date: Wed, 6 Aug 2025 06:07:06 +0000 (+1000) Subject: vfs: output mount_too_revealing() errors to fscontext X-Git-Tag: v6.18-rc1~240^2~2^2 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=807602d8cfc8b63e2c645fbbc66c8e82479ee311;p=thirdparty%2Flinux.git vfs: output mount_too_revealing() errors to fscontext It makes little sense for fsmount() to output the warning message when mount_too_revealing() is violated to kmsg. Instead, the warning should be output (with a "VFS" prefix) to the fscontext log. In addition, include the same log message for mount_too_revealing() when doing a regular mount for consistency. With the newest fsopen()-based mount(8) from util-linux, the error messages now look like # mount -t proc proc /tmp mount: /tmp: fsmount() failed: VFS: Mount too revealing. dmesg(1) may have more information after failed mount system call. which could finally result in mount_too_revealing() errors being easier for users to detect and understand. Signed-off-by: Aleksa Sarai Link: https://lore.kernel.org/20250806-errorfc-mount-too-revealing-v2-2-534b9b4d45bb@cyphar.com Signed-off-by: Christian Brauner --- diff --git a/fs/namespace.c b/fs/namespace.c index ddfd4457d3383..86d12f88b6885 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -3724,8 +3724,10 @@ static int do_new_mount_fc(struct fs_context *fc, struct path *mountpoint, int error; error = security_sb_kern_mount(sb); - if (!error && mount_too_revealing(sb, &mnt_flags)) + if (!error && mount_too_revealing(sb, &mnt_flags)) { + errorfcp(fc, "VFS", "Mount too revealing"); error = -EPERM; + } if (unlikely(error)) { fc_drop_locked(fc); @@ -4441,7 +4443,7 @@ SYSCALL_DEFINE3(fsmount, int, fs_fd, unsigned int, flags, ret = -EPERM; if (mount_too_revealing(fc->root->d_sb, &mnt_flags)) { - pr_warn("VFS: Mount too revealing\n"); + errorfcp(fc, "VFS", "Mount too revealing"); goto err_unlock; }