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Thu, 19 Jul 2018 20:13:44 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:47795 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731462AbeGTANn (ORCPT ); Thu, 19 Jul 2018 20:13:43 -0400 Received: from static-50-53-48-205.bvtn.or.frontiernet.net ([50.53.48.205] helo=[192.168.192.153]) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1fgILJ-0004mr-Dv; Thu, 19 Jul 2018 23:28:17 +0000 Subject: Re: [PATCH 1/2] apparmor: Check buffer bounds when mapping permissions mask To: Tyler Hicks Cc: James Morris , Serge Hallyn , Seth Arnold , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org References: <1530854701-7348-1-git-send-email-tyhicks@canonical.com> <1530854701-7348-2-git-send-email-tyhicks@canonical.com> From: John Johansen Openpgp: preference=signencrypt Autocrypt: addr=john.johansen@canonical.com; prefer-encrypt=mutual; keydata= xsFNBE5mrPoBEADAk19PsgVgBKkImmR2isPQ6o7KJhTTKjJdwVbkWSnNn+o6Up5knKP1f49E BQlceWg1yp/NwbR8ad+eSEO/uma/K+PqWvBptKC9SWD97FG4uB4/caomLEU97sLQMtnvGWdx rxVRGM4anzWYMgzz5TZmIiVTZ43Ou5VpaS1Vz1ZSxP3h/xKNZr/TcW5WQai8u3PWVnbkjhSZ PHv1BghN69qxEPomrJBm1gmtx3ZiVmFXluwTmTgJOkpFol7nbJ0ilnYHrA7SX3CtR1upeUpM a/WIanVO96WdTjHHIa43fbhmQube4txS3FcQLOJVqQsx6lE9B7qAppm9hQ10qPWwdfPy/+0W 6AWtNu5ASiGVCInWzl2HBqYd/Zll93zUq+NIoCn8sDAM9iH+wtaGDcJywIGIn+edKNtK72AM gChTg/j1ZoWH6ZeWPjuUfubVzZto1FMoGJ/SF4MmdQG1iQNtf4sFZbEgXuy9cGi2bomF0zvy BJSANpxlKNBDYKzN6Kz09HUAkjlFMNgomL/cjqgABtAx59L+dVIZfaF281pIcUZzwvh5+JoG eOW5uBSMbE7L38nszooykIJ5XrAchkJxNfz7k+FnQeKEkNzEd2LWc3QF4BQZYRT6PHHga3Rg ykW5+1wTMqJILdmtaPbXrF3FvnV0LRPcv4xKx7B3fGm7ygdoowARAQABzR1Kb2huIEpvaGFu c2VuIDxqb2huQGpqbXgubmV0PsLBegQTAQoAJAIbAwULCQgHAwUVCgkICwUWAgMBAAIeAQIX gAUCTo0YVwIZAQAKCRAFLzZwGNXD2LxJD/9TJZCpwlncTgYeraEMeDfkWv8c1IsM1j0AmE4V tL+fE780ZVP9gkjgkdYSxt7ecETPTKMaZSisrl1RwqU0oogXdXQSpxrGH01icu/2n0jcYSqY KggPxy78BGs2LZq4XPfJTZmHZGnXGq/eDr/mSnj0aavBJmMZ6jbiPz6yHtBYPZ9fdo8btczw P41YeWoIu26/8II6f0Xm3VC5oAa8v7Rd+RWZa8TMwlhzHExxel3jtI7IzzOsnmE9/8Dm0ARD 5iTLCXwR1cwI/J9BF/S1Xv8PN1huT3ItCNdatgp8zqoJkgPVjmvyL64Q3fEkYbfHOWsaba9/ kAVtBNz9RTFh7IHDfECVaToujBd7BtPqr+qIjWFadJD3I5eLCVJvVrrolrCATlFtN3YkQs6J n1AiIVIU3bHR8Gjevgz5Ll6SCGHgRrkyRpnSYaU/uLgn37N6AYxi/QAL+by3CyEFLjzWAEvy Q8bq3Iucn7JEbhS/J//dUqLoeUf8tsGi00zmrITZYeFYARhQMtsfizIrVDtz1iPf/ZMp5gRB niyjpXn131cm3M3gv6HrQsAGnn8AJru8GDi5XJYIco/1+x/qEiN2nClaAOpbhzN2eUvPDY5W 0q3bA/Zp2mfG52vbRI+tQ0Br1Hd/vsntUHO903mMZep2NzN3BZ5qEvPvG4rW5Zq2DpybWc7B TQROZqz6ARAAoqw6kkBhWyM1fvgamAVjeZ6nKEfnRWbkC94L1EsJLup3Wb2X0ABNOHSkbSD4 pAuC2tKF/EGBt5CP7QdVKRGcQzAd6b2c1Idy9RLw6w4gi+nn/d1Pm1kkYhkSi5zWaIg0m5RQ Uk+El8zkf5tcE/1N0Z5OK2JhjwFu5bX0a0l4cFGWVQEciVMDKRtxMjEtk3SxFalm6ZdQ2pp2 822clnq4zZ9mWu1d2waxiz+b5Ia4weDYa7n41URcBEUbJAgnicJkJtCTwyIxIW2KnVyOrjvk QzIBvaP0FdP2vvZoPMdlCIzOlIkPLgxE0IWueTXeBJhNs01pb8bLqmTIMlu4LvBELA/veiaj j5s8y542H/aHsfBf4MQUhHxO/BZV7h06KSUfIaY7OgAgKuGNB3UiaIUS5+a9gnEOQLDxKRy/ a7Q1v9S+Nvx+7j8iH3jkQJhxT6ZBhZGRx0gkH3T+F0nNDm5NaJUsaswgJrqFZkUGd2Mrm1qn KwXiAt8SIcENdq33R0KKKRC80Xgwj8Jn30vXLSG+NO1GH0UMcAxMwy/pvk6LU5JGjZR73J5U LVhH4MLbDggD3mPaiG8+fotTrJUPqqhg9hyUEPpYG7sqt74Xn79+CEZcjLHzyl6vAFE2W0kx lLtQtUZUHO36afFv8qGpO3ZqPvjBUuatXF6tvUQCwf3H6XMAEQEAAcLBXwQYAQoACQUCTmas +gIbDAAKCRAFLzZwGNXD2D/XD/0ddM/4ai1b+Tl1jznKajX3kG+MeEYeI4f40vco3rOLrnRG FOcbyyfVF69MKepie4OwoI1jcTU0ADecnbWnDNHpr0SczxBMro3bnrLhsmvjunTYIvssBZtB 4aVJjuLILPUlnhFqa7fbVq0ZQjbiV/rt2jBENdm9pbJZ6GjnpYIcAbPCCa/ffL4/SQRSYHXo hGiiS4y5jBTmK5ltfewLOw02fkexH+IJFrrGBXDSg6n2Sgxnn++NF34fXcm9piaw3mKsICm+ 0hdNh4afGZ6IWV8PG2teooVDp4dYih++xX/XS8zBCc1O9w4nzlP2gKzlqSWbhiWpifRJBFa4 WtAeJTdXYd37j/BI4RWWhnyw7aAPNGj33ytGHNUf6Ro2/jtj4tF1y/QFXqjJG/wGjpdtRfbt UjqLHIsvfPNNJq/958p74ndACidlWSHzj+Op26KpbFnmwNO0psiUsnhvHFwPO/vAbl3RsR5+ 0Ro+hvs2cEmQuv9r/bDlCfpzp2t3cK+rhxUqisOx8DZfz1BnkaoCRFbvvvk+7L/fomPntGPk qJciYE8TGHkZw1hOku+4OoM2GB5nEDlj+2TF/jLQ+EipX9PkPJYvxfRlC6dK8PKKfX9KdfmA IcgHfnV1jSn+8yH2djBPtKiqW0J69aIsyx7iV/03paPCjJh7Xq9vAzydN5U/UA== Organization: Canonical Message-ID: Date: Thu, 19 Jul 2018 16:28:14 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <1530854701-7348-2-git-send-email-tyhicks@canonical.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/05/2018 10:25 PM, Tyler Hicks wrote: > Don't read past the end of the buffer containing permissions > characters or write past the end of the destination string. > > Detected by CoverityScan CID#1415361, 1415376 ("Out-of-bounds access") > > Fixes: e53cfe6c7caa ("apparmor: rework perm mapping to a slightly broader set") > Signed-off-by: Tyler Hicks I've pulled this into apparmor-next with a minor modification noted below > security/apparmor/file.c | 3 ++- > security/apparmor/include/perms.h | 3 ++- > security/apparmor/lib.c | 17 +++++++++++++---- > 3 files changed, 17 insertions(+), 6 deletions(-) > > diff --git a/security/apparmor/file.c b/security/apparmor/file.c > index 224b2fef93ca..4285943f7260 100644 > --- a/security/apparmor/file.c > +++ b/security/apparmor/file.c > @@ -47,7 +47,8 @@ static void audit_file_mask(struct audit_buffer *ab, u32 mask) > { > char str[10]; > > - aa_perm_mask_to_str(str, aa_file_perm_chrs, map_mask_to_chr_mask(mask)); > + aa_perm_mask_to_str(str, sizeof(str), aa_file_perm_chrs, > + map_mask_to_chr_mask(mask)); > audit_log_string(ab, str); > } > > diff --git a/security/apparmor/include/perms.h b/security/apparmor/include/perms.h > index 38aa6247d00f..b94ec114d1a4 100644 > --- a/security/apparmor/include/perms.h > +++ b/security/apparmor/include/perms.h > @@ -137,7 +137,8 @@ extern struct aa_perms allperms; > xcheck(fn_for_each((L1), (P), (FN1)), fn_for_each((L2), (P), (FN2))) > > > -void aa_perm_mask_to_str(char *str, const char *chrs, u32 mask); > +void aa_perm_mask_to_str(char *str, size_t str_size, const char *chrs, > + u32 mask); > void aa_audit_perm_names(struct audit_buffer *ab, const char * const *names, > u32 mask); > void aa_audit_perm_mask(struct audit_buffer *ab, u32 mask, const char *chrs, > diff --git a/security/apparmor/lib.c b/security/apparmor/lib.c > index a7b3f681b80e..7ab368c3789b 100644 > --- a/security/apparmor/lib.c > +++ b/security/apparmor/lib.c > @@ -198,15 +198,24 @@ const char *aa_file_perm_names[] = { > /** > * aa_perm_mask_to_str - convert a perm mask to its short string > * @str: character buffer to store string in (at least 10 characters) > + * @str_size: size of the @str buffer > + * @chrs: NUL-terminated character buffer of permission characters > * @mask: permission mask to convert > */ > -void aa_perm_mask_to_str(char *str, const char *chrs, u32 mask) > +void aa_perm_mask_to_str(char *str, size_t str_size, const char *chrs, u32 mask) > { > unsigned int i, perm = 1; > + size_t num_chrs = strlen(chrs); > + > + for (i = 0; i < num_chrs; perm <<= 1, i++> + if (mask & perm) { > + /* Ensure that one byte is left for NUL-termination */ > + if (WARN_ON_ONCE(str_size <= 1)) > + continue; might as well break here > > - for (i = 0; i < 32; perm <<= 1, i++) { > - if (mask & perm) > *str++ = chrs[i]; > + str_size--; > + } > } > *str = '\0'; > } > @@ -236,7 +245,7 @@ void aa_audit_perm_mask(struct audit_buffer *ab, u32 mask, const char *chrs, > > audit_log_format(ab, "\""); > if ((mask & chrsmask) && chrs) { > - aa_perm_mask_to_str(str, chrs, mask & chrsmask); > + aa_perm_mask_to_str(str, sizeof(str), chrs, mask & chrsmask); > mask &= ~chrsmask; > audit_log_format(ab, "%s", str); > if (mask & namesmask) >