From patchwork Thu Nov 16 19:21:23 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 13458198 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="Obwa6NhB" Received: from mail-pl1-x632.google.com (mail-pl1-x632.google.com [IPv6:2607:f8b0:4864:20::632]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4A68ED5B for ; Thu, 16 Nov 2023 11:21:30 -0800 (PST) Received: by mail-pl1-x632.google.com with SMTP id d9443c01a7336-1cc3216b2a1so10798045ad.2 for ; Thu, 16 Nov 2023 11:21:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1700162489; x=1700767289; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=JcOGCvfEagiw1YdvVb5+RIJk8AKqAaDYL4V7FygIVew=; b=Obwa6NhB3UvqEPYIY/eSPoywDnIy6qI94KyzaKOwFxO0bvBS8qUe28NohbTj6++iDz kChhiWkx+A683O/yoCYMHL6z8K8RrRJIaBQfNOJOwI/njVXcAODwOCKfdy10liYXLQCN bQQPOxHFJ/Kzudt9tTrE6JIeD4Jlz/yny339c= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1700162489; x=1700767289; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=JcOGCvfEagiw1YdvVb5+RIJk8AKqAaDYL4V7FygIVew=; b=norjNjN0YAv5ACIuOMB9TKGkNaVz5mV6iK6oPPad7r8m+beBkNdo0mDRFZj4ytG3SS e/ffmCKWJK5FsatUrh2Cp+/uwh1aeRmYYfQ7Zf/a/jZ0oqetT+Uqzb/jfgajtRot/j7V jld5IPEL1Kdafw2nnJcIDbE59jdullwOouv5RMYaZ54VKuUU9az4tipn3UnC66Q/5YEx EaMNTBW738c7OW3yMHCus2EO3aeLi8nwHQeKzY+S7AJVSjHdlybZwxYaAHcJGknOLHpH OpdfgXRjIQiy0QOkOKF+GciLiNQRztAZP48glwemUQiHg0KidIJaBlXtiF7OGe0lT9ID ElXA== X-Gm-Message-State: AOJu0YzWm0wpEroxgYpJBZsKQIhTgKwcE23RFOzCeXxDKYfYmzvR5VMT RJyOhsdCfNkoxtGYDOvlmu0/ag== X-Google-Smtp-Source: AGHT+IGaGl07eSgYy3o8f6edP1SkNwCS66RrUaUOhWuRJ+oeJxlMHbJLhbzYWUfIGXmL8cR8NFc1fQ== X-Received: by 2002:a17:902:eccb:b0:1cc:3c2f:9c41 with SMTP id a11-20020a170902eccb00b001cc3c2f9c41mr11600739plh.23.1700162489608; Thu, 16 Nov 2023 11:21:29 -0800 (PST) Received: from www.outflux.net (198-0-35-241-static.hfc.comcastbusiness.net. [198.0.35.241]) by smtp.gmail.com with ESMTPSA id c5-20020a170902c1c500b001c32fd9e412sm28083plc.58.2023.11.16.11.21.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Nov 2023 11:21:28 -0800 (PST) From: Kees Cook To: Greg Kroah-Hartman Cc: Kees Cook , Tejun Heo , Azeem Shaikh , Zefan Li , Johannes Weiner , Waiman Long , Steven Rostedt , Masami Hiramatsu , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH 1/3] kernfs: Convert kernfs_walk_ns() from strlcpy() to strscpy() Date: Thu, 16 Nov 2023 11:21:23 -0800 Message-Id: <20231116192127.1558276-1-keescook@chromium.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231116191718.work.246-kees@kernel.org> References: <20231116191718.work.246-kees@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1547; i=keescook@chromium.org; h=from:subject; bh=RC/7LXkyyLguxbbh56shJCtsntlpj0v42+8lbCHyU+Q=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBlVmu1a6YGdzhkpS/cBY9OTj5JYo8XAMY6N0Jto saH/INeq++JAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCZVZrtQAKCRCJcvTf3G3A JmvvD/4hr2r1X4hdNRSGjLQ0H9OzAANSFcbnzJfaOanKtWw5cPHnrunF87wYSMyErB4/oiEJRLs 0HkPFaj2BH5MXTVv4dNNPgNWv5sV7AbzxG+f3fdi3csPn3hTlnA4J8ugnwhU3piG8gYUOWP6vaT pf2p3JEknP9h4DK51GSgbULEBrBYo1PRWXKa2joQA3vkfWjunJoR0FEiNFlzm5LCYqb3YhBtws2 qofYsgxWF2wfkKO5nKlGyFyarUQfJ2RVLsIi+UMDpBVzO42U3VZyQlhkTcg7EkmOtudofwdBXK4 0+Zm3jPk2zNGJfle1nY4jU9/mDukzZNJUhKagSnXYbf5JjntQ7n4HGFwaX9TsjyVmzhTrQ7gdqH krL0I5ky99HtHXMTUGWqyOUxwp1/VVdvp1umcCodYwkiptU0kKhbx96z/sFfT293wXWmcJHrilQ QVO4JiJSrQalFRzNYTvKQA+liozKhtf+rCDc7PfrRykroARPwmlXWBN8MXyEHTG8usj0LM/5lqE TLTHGNwFkf2LPoPdSdt1FYYpM+d8aCyWbqWuAryypw63HLRYP6tMyXNhMc36X9s3wo4404dXooj /EGJXy98yYJx8ykG85Ru2S1uYthlhKQQ2MpUBixq+dLxTB6qtI9vJoywzOpi3tqIINg3BntSh2t jIEaboOkD87aMGQ== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 strlcpy() reads the entire source buffer first. This read may exceed the destination size limit. This is both inefficient and can lead to linear read overflows if a source string is not NUL-terminated[1]. Additionally, it returns the size of the source string, not the resulting size of the destination string. In an effort to remove strlcpy() completely[2], replace strlcpy() here with strscpy(). Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy [1] Link: https://github.com/KSPP/linux/issues/89 [2] Cc: Greg Kroah-Hartman Cc: Tejun Heo Cc: Azeem Shaikh Signed-off-by: Kees Cook --- fs/kernfs/dir.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 8b2bd65d70e7..37353901ede1 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -850,16 +850,16 @@ static struct kernfs_node *kernfs_walk_ns(struct kernfs_node *parent, const unsigned char *path, const void *ns) { - size_t len; + ssize_t len; char *p, *name; lockdep_assert_held_read(&kernfs_root(parent)->kernfs_rwsem); spin_lock_irq(&kernfs_pr_cont_lock); - len = strlcpy(kernfs_pr_cont_buf, path, sizeof(kernfs_pr_cont_buf)); + len = strscpy(kernfs_pr_cont_buf, path, sizeof(kernfs_pr_cont_buf)); - if (len >= sizeof(kernfs_pr_cont_buf)) { + if (len < 0) { spin_unlock_irq(&kernfs_pr_cont_lock); return NULL; } From patchwork Thu Nov 16 19:21:24 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 13458196 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="gksdvUXO" Received: from mail-pf1-x436.google.com (mail-pf1-x436.google.com [IPv6:2607:f8b0:4864:20::436]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CF85AD4D for ; Thu, 16 Nov 2023 11:21:28 -0800 (PST) Received: by mail-pf1-x436.google.com with SMTP id d2e1a72fcca58-6b5cac99cfdso1110867b3a.2 for ; Thu, 16 Nov 2023 11:21:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1700162488; x=1700767288; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=uIo7yB6lg0mEMstu2RR7JQJ7c10/IQwKA8lnXu5L+VQ=; b=gksdvUXOqQfywnZfE/U/dRvbFNoqk2OdL1XDO2JtjQ5v8cHKjYv+3HHvN3Xc2t4pxx jYl0X/SE/yNf57xIwCVKy9YYoToydy5pimU0FbJ9e5ILq8XV65nWX5Ry0h5f/xv0Ux/8 tmHpMPZUHqFGvTd83KfjtCu13x5CmwEB9NQs4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1700162488; x=1700767288; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=uIo7yB6lg0mEMstu2RR7JQJ7c10/IQwKA8lnXu5L+VQ=; b=cf0o7072WC+UCyrNBj9LKj0jM6LtNK/YmGrpsT9j+ibrHXpnRju6YksSn0vG1Va/oe e6ihDHWsgJOMGCUem2HVDteL1NnT1oSWnYml7OT4je38LTJ9Dig9oi6Ghmp1YndjAU/E m+0m99aBAR7FNC1cFpz6CVF+djf8TSDJTTFj9u8nLStRaWqy9Nb6+FcQ5Rbd9b6MQZY+ Yu5SWwHk6YR7+OqNOgAF+Q2c0oP/nnBYLAQjrSMYBSyxMkMhGx5ykoLWVEQHvMl3neIW NdL+FEdqXP3fklWbKmLO2eTHWoKXf+fdt0pZA8/YhQVc5ILiq6BJS1jZ40d7612TmRB0 /plg== X-Gm-Message-State: AOJu0YxXJIcKmZ9QHnsDZrThBlb/zX48qXKFllzf3jCzgCL53OipeNc8 SSwp+IWwg0cAr/VY4w2qHkOmvw== X-Google-Smtp-Source: AGHT+IEwPnM9Dx2nNDBuGD4lru9jT+pK5qmTq2kW6VUI6EBCZ4wKKaLw5OQNeQMU1nuyaJhO1qo8DA== X-Received: by 2002:a05:6a20:daa8:b0:186:6cb3:477 with SMTP id iy40-20020a056a20daa800b001866cb30477mr16580809pzb.28.1700162488340; Thu, 16 Nov 2023 11:21:28 -0800 (PST) Received: from www.outflux.net (198-0-35-241-static.hfc.comcastbusiness.net. [198.0.35.241]) by smtp.gmail.com with ESMTPSA id c9-20020a056a00008900b0066a31111cc5sm83004pfj.152.2023.11.16.11.21.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Nov 2023 11:21:27 -0800 (PST) From: Kees Cook To: Greg Kroah-Hartman Cc: Kees Cook , Tejun Heo , Azeem Shaikh , Zefan Li , Johannes Weiner , Waiman Long , Steven Rostedt , Masami Hiramatsu , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH 2/3] kernfs: Convert kernfs_name_locked() from strlcpy() to strscpy() Date: Thu, 16 Nov 2023 11:21:24 -0800 Message-Id: <20231116192127.1558276-2-keescook@chromium.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231116191718.work.246-kees@kernel.org> References: <20231116191718.work.246-kees@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2557; i=keescook@chromium.org; h=from:subject; bh=LRsHUfYO0eDcNqxdqH4Irr7bDjuYf6fIiWZiwxT3W+g=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBlVmu1weRodlm3lOcUmdMyw49wlyXCXGK9aCKK5 leBJkEo/2GJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCZVZrtQAKCRCJcvTf3G3A Jg/BD/wIwwRk/W4vfmpcw3JeNwWAhbL25AwyJuBta59Of8OWThCkAoKsImJQHA/3k2NBUNS2Fwi S8ZiHqT8qaygVtCmErykGZeBzNtYaTjfHOBTZfiKjDX1YrdFjtjbW9VOeHR3vkDfDErswrhlklf 22E55Z+V/rJHaf7jmrXD1k6ABqlVNQYs9jxxCJSSy/GwygBrxwJ1KcH4qp66EV0dcN04q/BhCOT ZUqjqaD1nN4eGnS8nEUvxSuwhxKt7qAX9zWWe6r1rdjN3iNxhyXDMooCa6tKQXlSwpdVlkqdT69 gGSs7tLucDzx3R6aVpQsR4+s9RhM3sgsArYgpKaJEsSNmYqCAeG4/7VNNombjfWw0Bjz697xIDY lN3nUchv53ibE3bW5hNhK32eWaq7fXoyhr++bVF4iWgVb1YhvxMhD4iCDFNmg7oqEMUTpWzBzdn 3U631WffbyCMCgSZZdr589/vR4ATcXf61J+X20n4pRN62zGTVvn742alOwMwzeu4BbeOuux1hfr lH8vjyDbNIatVWrktpNj5NZdHdoeQttsZgKMNrNjZ+y5kEKZ19+iLv1eGJl5INgxQ8Hjd/UP25K eOJ34S69uiPxy6L/8n3mz4Tql8Ib5tSlG2VloXBwZBuu22BVA0p+0KJ5VufGbgJqqa3OCnwYFml 1S7SeuZU1GbAWjQ== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 strlcpy() reads the entire source buffer first. This read may exceed the destination size limit. This is both inefficient and can lead to linear read overflows if a source string is not NUL-terminated[1]. Additionally, it returns the size of the source string, not the resulting size of the destination string. In an effort to remove strlcpy() completely[2], replace strlcpy() here with strscpy(). Nothing actually checks the return value coming from kernfs_name_locked(), so this has no impact on error paths. The caller hierarchy is: kernfs_name_locked() kernfs_name() pr_cont_kernfs_name() return value ignored cgroup_name() current_css_set_cg_links_read() return value ignored print_page_owner_memcg() return value ignored Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy [1] Link: https://github.com/KSPP/linux/issues/89 [2] Cc: Greg Kroah-Hartman Cc: Tejun Heo Cc: Azeem Shaikh Signed-off-by: Kees Cook --- fs/kernfs/dir.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 37353901ede1..8c0e5442597e 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -54,9 +54,9 @@ static bool kernfs_lockdep(struct kernfs_node *kn) static int kernfs_name_locked(struct kernfs_node *kn, char *buf, size_t buflen) { if (!kn) - return strlcpy(buf, "(null)", buflen); + return strscpy(buf, "(null)", buflen); - return strlcpy(buf, kn->parent ? kn->name : "/", buflen); + return strscpy(buf, kn->parent ? kn->name : "/", buflen); } /* kernfs_node_depth - compute depth from @from to @to */ @@ -182,12 +182,12 @@ static int kernfs_path_from_node_locked(struct kernfs_node *kn_to, * @buflen: size of @buf * * Copies the name of @kn into @buf of @buflen bytes. The behavior is - * similar to strlcpy(). + * similar to strscpy(). * * Fills buffer with "(null)" if @kn is %NULL. * - * Return: the length of @kn's name and if @buf isn't long enough, - * it's filled up to @buflen-1 and nul terminated. + * Return: the resulting length of @buf. If @buf isn't long enough, + * it's filled up to @buflen-1 and nul terminated, and returns -E2BIG. * * This function can be called from any context. */ From patchwork Thu Nov 16 19:21:25 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 13458197 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="RpEODg+X" Received: from mail-pl1-x62c.google.com (mail-pl1-x62c.google.com [IPv6:2607:f8b0:4864:20::62c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 323D4D53 for ; Thu, 16 Nov 2023 11:21:29 -0800 (PST) Received: by mail-pl1-x62c.google.com with SMTP id d9443c01a7336-1cc5b705769so10680705ad.0 for ; Thu, 16 Nov 2023 11:21:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1700162488; x=1700767288; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=3lQXUPDHwSb3W7AzEHeGiPOMrGqRC++G0/30oWFYpys=; b=RpEODg+XwhY1Acp+PJDOELMbmRUAu+D/Xoo/xYstpBTnWmMA8vGKzxqZiGQWUkc90K 0lqw7UTGl1A4RJrJOIx7tbByfWwplwdStr18BLcAl7oZvcT51JQEfcCWKRKf2BwzlQEe Ab3h0t1Gqb5zCp26IZefLYGUCK02m7kkihq8k= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1700162488; x=1700767288; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=3lQXUPDHwSb3W7AzEHeGiPOMrGqRC++G0/30oWFYpys=; b=eh+TrYML5CSq9QN1OODN8gY/g5Ly+9clR7i30R4Lbj5Qo1+asa4Q5H5Yjn+kjDSh2o jAESjrWR+GPc1VyVyk3cXnCmgH4C2sH7ICbZV4O7avjclwebov3H8uvZGdhW7/TjF8St Y8tKstDF50YBpXSeOihLJvziwZATJyb5L8AZ3CODe0s5ojak/ExuhOb3GWcriH+cVw51 ai5cS3TpNxzcms3zfxC7pDEnRSr9+V7li5+pxMGlgT3cGBkpYUJiEAKc9mwTjWnJZDYy QU15/ZCA/JILZIJMut2E+PQJCQ+Fr8FqmGlrOSjit3idAgiDhPtSIEdxgpo2K6lzg8si XQrQ== X-Gm-Message-State: AOJu0Yx5e5APKpXLRrEOWt44TpB7ktG+wc/rXtUi90LIG0tal+i6DvOn VaVlR4njiVZB14e0OIUHCchcdQ== X-Google-Smtp-Source: AGHT+IFm4YG/oaCFmEfgYf5uoVxckTreZ/Bctw5PNDreTVWHEYt0BKCZHpmtNgXlkwhnO8LZx1T2bQ== X-Received: by 2002:a17:903:18e:b0:1ce:1674:fd15 with SMTP id z14-20020a170903018e00b001ce1674fd15mr11527634plg.65.1700162488598; Thu, 16 Nov 2023 11:21:28 -0800 (PST) Received: from www.outflux.net (198-0-35-241-static.hfc.comcastbusiness.net. [198.0.35.241]) by smtp.gmail.com with ESMTPSA id b4-20020a170902d50400b001c72c07c9d9sm5592plg.308.2023.11.16.11.21.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Nov 2023 11:21:28 -0800 (PST) From: Kees Cook To: Greg Kroah-Hartman Cc: Kees Cook , Tejun Heo , Zefan Li , Johannes Weiner , Waiman Long , Steven Rostedt , Masami Hiramatsu , cgroups@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Azeem Shaikh , linux-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH 3/3] kernfs: Convert kernfs_path_from_node_locked() from strlcpy() to strscpy() Date: Thu, 16 Nov 2023 11:21:25 -0800 Message-Id: <20231116192127.1558276-3-keescook@chromium.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231116191718.work.246-kees@kernel.org> References: <20231116191718.work.246-kees@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=8689; i=keescook@chromium.org; h=from:subject; bh=sje9v6D9QIFWWAiLZIxMhxCeRGV4qg03i4fKPc7SIN8=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBlVmu1NoUIjydK+VgXZJN4O+Ab2Ex2hdoHKlPJH FjXVvdTYYGJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCZVZrtQAKCRCJcvTf3G3A Jp/ZD/9/pX2tZ6bCcNKw/mYnC600HioBD2eNF1Vpf+wZoqJfvliJ824E7lu7kXMWB6xkrFuSDRQ HO7NELU2wWMz7ebzzgo2cM4inj0pnKRoqVGy0KKwvqZraO+yEElTI8tP5Upv4sSFPswbAE0hbw8 SH2AAbx1+7DuvTJYHheHSkZQvxl9Vts+ZEt8v/VljlGtf9vgcHJLc6Ps0pBzsvLWwJibBuW0ixs l7UjIy3+Rqe1HUYOlIqJU2pfDyiA8qyI2oUPvKERjwyBEhG1lyoSCfomFFXHbRyip1lGJbQzVuG lxIBcKENShb9BFVjDZ75DeZUmCpzZ3hTH2tCmbkLow+30wZb0rkTzqDUU+cS9TFK/JwySY6FEOU QGHoMFWSmhHbOf3WfIS1Xl4tsI2FuvqZy3L3L+HiVK9Ig4DOLEqCc8rbLn6oyVhb2GIAENUZt/r 2UD1BGAVkUAgu5Q9qcOR8q5PPNP1wJeE9rY+l8DY1Os2TijocUPtYzM36KaqEg8LWqqMoZ7iF5u 3Q4XeYxLv1dk1bCOX9pBnd7zuUTekZx+/RUQ/i/WhlQrpCYLnzMtI1m43jfoeTbOWPB3yVmxy33 4JWoKITXKwIpGGLlwlig9otmxMoQ9xG3Nz8oZRw6CWvBxnGPEIMXCDVim7aIKnMs2jZZTETIToD APj6swjaf4Y7M5A== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 One of the last remaining users of strlcpy() in the kernel is kernfs_path_from_node_locked(), which passes back the problematic "length we _would_ have copied" return value to indicate truncation. Convert the chain of all callers to use the negative return value (some of which already doing this explicitly). All callers were already also checking for negative return values, so the risk to missed checks looks very low. In this analysis, it was found that cgroup1_release_agent() actually didn't handle the "too large" condition, so this is technically also a bug fix. :) Here's the chain of callers, and resolution identifying each one as now handling the correct return value: kernfs_path_from_node_locked() kernfs_path_from_node() pr_cont_kernfs_path() returns void kernfs_path() sysfs_warn_dup() return value ignored cgroup_path() blkg_path() bfq_bic_update_cgroup() return value ignored TRACE_IOCG_PATH() return value ignored TRACE_CGROUP_PATH() return value ignored perf_event_cgroup() return value ignored task_group_path() return value ignored damon_sysfs_memcg_path_eq() return value ignored get_mm_memcg_path() return value ignored lru_gen_seq_show() return value ignored cgroup_path_from_kernfs_id() return value ignored cgroup_show_path() already converted "too large" error to negative value cgroup_path_ns_locked() cgroup_path_ns() bpf_iter_cgroup_show_fdinfo() return value ignored cgroup1_release_agent() wasn't checking "too large" error proc_cgroup_show() already converted "too large" to negative value Cc: Greg Kroah-Hartman Cc: Tejun Heo Cc: Zefan Li Cc: Johannes Weiner Cc: Waiman Long Cc: Steven Rostedt Cc: Masami Hiramatsu Cc: cgroups@vger.kernel.org Cc: linux-trace-kernel@vger.kernel.org Co-developed-by: Azeem Shaikh Signed-off-by: Azeem Shaikh Signed-off-by: Kees Cook --- fs/kernfs/dir.c | 37 ++++++++++++++++++++----------------- kernel/cgroup/cgroup-v1.c | 2 +- kernel/cgroup/cgroup.c | 4 ++-- kernel/cgroup/cpuset.c | 2 +- kernel/trace/trace_uprobe.c | 2 +- 5 files changed, 25 insertions(+), 22 deletions(-) diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 8c0e5442597e..183f353b3852 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -127,7 +127,7 @@ static struct kernfs_node *kernfs_common_ancestor(struct kernfs_node *a, * * [3] when @kn_to is %NULL result will be "(null)" * - * Return: the length of the full path. If the full length is equal to or + * Return: the length of the constructed path. If the path would have been * greater than @buflen, @buf contains the truncated path with the trailing * '\0'. On error, -errno is returned. */ @@ -138,16 +138,17 @@ static int kernfs_path_from_node_locked(struct kernfs_node *kn_to, struct kernfs_node *kn, *common; const char parent_str[] = "/.."; size_t depth_from, depth_to, len = 0; + ssize_t copied; int i, j; if (!kn_to) - return strlcpy(buf, "(null)", buflen); + return strscpy(buf, "(null)", buflen); if (!kn_from) kn_from = kernfs_root(kn_to)->kn; if (kn_from == kn_to) - return strlcpy(buf, "/", buflen); + return strscpy(buf, "/", buflen); common = kernfs_common_ancestor(kn_from, kn_to); if (WARN_ON(!common)) @@ -158,18 +159,22 @@ static int kernfs_path_from_node_locked(struct kernfs_node *kn_to, buf[0] = '\0'; - for (i = 0; i < depth_from; i++) - len += strlcpy(buf + len, parent_str, - len < buflen ? buflen - len : 0); + for (i = 0; i < depth_from; i++) { + copied = strscpy(buf + len, parent_str, buflen - len); + if (copied < 0) + return copied; + len += copied; + } /* Calculate how many bytes we need for the rest */ for (i = depth_to - 1; i >= 0; i--) { for (kn = kn_to, j = 0; j < i; j++) kn = kn->parent; - len += strlcpy(buf + len, "/", - len < buflen ? buflen - len : 0); - len += strlcpy(buf + len, kn->name, - len < buflen ? buflen - len : 0); + + copied = scnprintf(buf + len, buflen - len, "/%s", kn->name); + if (copied < 0) + return copied; + len += copied; } return len; @@ -214,7 +219,7 @@ int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen) * path (which includes '..'s) as needed to reach from @from to @to is * returned. * - * Return: the length of the full path. If the full length is equal to or + * Return: the length of the constructed path. If the path would have been * greater than @buflen, @buf contains the truncated path with the trailing * '\0'. On error, -errno is returned. */ @@ -265,12 +270,10 @@ void pr_cont_kernfs_path(struct kernfs_node *kn) sz = kernfs_path_from_node(kn, NULL, kernfs_pr_cont_buf, sizeof(kernfs_pr_cont_buf)); if (sz < 0) { - pr_cont("(error)"); - goto out; - } - - if (sz >= sizeof(kernfs_pr_cont_buf)) { - pr_cont("(name too long)"); + if (sz == -E2BIG) + pr_cont("(name too long)"); + else + pr_cont("(error)"); goto out; } diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c index 76db6c67e39a..9cb00ebe9ac6 100644 --- a/kernel/cgroup/cgroup-v1.c +++ b/kernel/cgroup/cgroup-v1.c @@ -802,7 +802,7 @@ void cgroup1_release_agent(struct work_struct *work) goto out_free; ret = cgroup_path_ns(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns); - if (ret < 0 || ret >= PATH_MAX) + if (ret < 0) goto out_free; argv[0] = agentbuf; diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 1d5b9de3b1b9..3a04db0d1fe6 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -1893,7 +1893,7 @@ int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node, len = kernfs_path_from_node(kf_node, ns_cgroup->kn, buf, PATH_MAX); spin_unlock_irq(&css_set_lock); - if (len >= PATH_MAX) + if (len == -E2BIG) len = -ERANGE; else if (len > 0) { seq_escape(sf, buf, " \t\n\\"); @@ -6313,7 +6313,7 @@ int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns, if (cgroup_on_dfl(cgrp) || !(tsk->flags & PF_EXITING)) { retval = cgroup_path_ns_locked(cgrp, buf, PATH_MAX, current->nsproxy->cgroup_ns); - if (retval >= PATH_MAX) + if (retval == -E2BIG) retval = -ENAMETOOLONG; if (retval < 0) goto out_unlock; diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 615daaf87f1f..fb29158ae825 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -4941,7 +4941,7 @@ int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns, retval = cgroup_path_ns(css->cgroup, buf, PATH_MAX, current->nsproxy->cgroup_ns); css_put(css); - if (retval >= PATH_MAX) + if (retval == -E2BIG) retval = -ENAMETOOLONG; if (retval < 0) goto out_free; diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c index 99c051de412a..a84b85d8aac1 100644 --- a/kernel/trace/trace_uprobe.c +++ b/kernel/trace/trace_uprobe.c @@ -151,7 +151,7 @@ fetch_store_string(unsigned long addr, void *dest, void *base) return -ENOMEM; if (addr == FETCH_TOKEN_COMM) - ret = strlcpy(dst, current->comm, maxlen); + ret = strscpy(dst, current->comm, maxlen); else ret = strncpy_from_user(dst, src, maxlen); if (ret >= 0) {