From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E201F1D416E; Wed, 6 Nov 2024 12:12:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730895146; cv=none; b=Q1t5HpHq32Z3+8H7D8ZICTBNwWomKdiUwYzP+W15T3jCjK4J9YKVG23XZiN1XpNrtIEs6IttIBU2oyrXJvBtEjaGWfFsr5GNkhysa2kUmu1OUF1YsAyziqD8uZi1Hhh3VD4Au55wJBBPwXDn1Kusw08eYi37iK2O2SHkRwbPV/k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730895146; c=relaxed/simple; bh=5gitSoNZ/m/G2BD9GlUezmRUa5P2P7pWQMAq+x+MSCI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=aeyjLYOygKVOV+IS7UTCBy7JgRFQrn7kG9eMNLlve4z2cSAi40skobu40lIBiHlzPgtvE4TmjIGtfbLiCtWOJW+OcOMyIvGLtlF6emKm29TtvJdQNvJKsZ/jDWOyqy8MXbRsuA6UYM/4le52npGS7j72NyiTojy13E6B/nMvfZE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=cVXkFI5n; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="cVXkFI5n" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 35CAEC4CED2; Wed, 6 Nov 2024 12:12:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1730895145; bh=5gitSoNZ/m/G2BD9GlUezmRUa5P2P7pWQMAq+x+MSCI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cVXkFI5nH+WeUUMnQxfQYAUm+5OPGpJJxJnAgQUWL07iM95MWnNcLyMDpXe8Lklj5 vkBlFpOnLE3RhZEmpsHY/mobKw+2jjgcwCCFF59x5U85VJnsOySQMggEHbSeuuY7cn 2Q7HhgwSOHGSmhmsW3X5PNYd7Y8ERjtdTsAwbg4w= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Al Viro , Casey Schaufler , Christian Brauner , James Morris , Jann Horn , Ondrej Mosnacek , Paul Moore , "Serge E. Hallyn" , Stephen Smalley , =?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?= Subject: [PATCH 4.19 119/350] fs: Fix file_set_fowner LSM hook inconsistencies Date: Wed, 6 Nov 2024 13:00:47 +0100 Message-ID: <20241106120323.845811520@linuxfoundation.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241106120320.865793091@linuxfoundation.org> References: <20241106120320.865793091@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mickaël Salaün commit 26f204380a3c182e5adf1a798db0724d6111b597 upstream. The fcntl's F_SETOWN command sets the process that handle SIGIO/SIGURG for the related file descriptor. Before this change, the file_set_fowner LSM hook was always called, ignoring the VFS logic which may not actually change the process that handles SIGIO (e.g. TUN, TTY, dnotify), nor update the related UID/EUID. Moreover, because security_file_set_fowner() was called without lock (e.g. f_owner.lock), concurrent F_SETOWN commands could result to a race condition and inconsistent LSM states (e.g. SELinux's fown_sid) compared to struct fown_struct's UID/EUID. This change makes sure the LSM states are always in sync with the VFS state by moving the security_file_set_fowner() call close to the UID/EUID updates and using the same f_owner.lock . Rename f_modown() to __f_setown() to simplify code. Cc: stable@vger.kernel.org Cc: Al Viro Cc: Casey Schaufler Cc: Christian Brauner Cc: James Morris Cc: Jann Horn Cc: Ondrej Mosnacek Cc: Paul Moore Cc: Serge E. Hallyn Cc: Stephen Smalley Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Mickaël Salaün Signed-off-by: Paul Moore Signed-off-by: Greg Kroah-Hartman --- fs/fcntl.c | 14 ++++---------- 1 file changed, 4 insertions(+), 10 deletions(-) --- a/fs/fcntl.c +++ b/fs/fcntl.c @@ -84,8 +84,8 @@ static int setfl(int fd, struct file * f return error; } -static void f_modown(struct file *filp, struct pid *pid, enum pid_type type, - int force) +void __f_setown(struct file *filp, struct pid *pid, enum pid_type type, + int force) { write_lock_irq(&filp->f_owner.lock); if (force || !filp->f_owner.pid) { @@ -95,19 +95,13 @@ static void f_modown(struct file *filp, if (pid) { const struct cred *cred = current_cred(); + security_file_set_fowner(filp); filp->f_owner.uid = cred->uid; filp->f_owner.euid = cred->euid; } } write_unlock_irq(&filp->f_owner.lock); } - -void __f_setown(struct file *filp, struct pid *pid, enum pid_type type, - int force) -{ - security_file_set_fowner(filp); - f_modown(filp, pid, type, force); -} EXPORT_SYMBOL(__f_setown); int f_setown(struct file *filp, unsigned long arg, int force) @@ -143,7 +137,7 @@ EXPORT_SYMBOL(f_setown); void f_delown(struct file *filp) { - f_modown(filp, NULL, PIDTYPE_TGID, 1); + __f_setown(filp, NULL, PIDTYPE_TGID, 1); } pid_t f_getown(struct file *filp)