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Tue, 24 Sep 2019 13:01:34 -0400 Received: from static-50-53-33-191.bvtn.or.frontiernet.net ([50.53.33.191] helo=[192.168.192.153]) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1iCoBw-0000q2-7w; Tue, 24 Sep 2019 17:01:32 +0000 Subject: Re: [WTF?] aafs_create_symlink() weirdness To: Al Viro Cc: linux-kernel@vger.kernel.org References: <20190924020348.GD26530@ZenIV.linux.org.uk> 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: Tue, 24 Sep 2019 10:01:30 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190924020348.GD26530@ZenIV.linux.org.uk> 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 9/23/19 7:03 PM, Al Viro wrote: WTF indeed > > static struct dentry *aafs_create_symlink(const char *name, > struct dentry *parent, > const char *target, > void *private, > const struct inode_operations *iops) > { > struct dentry *dent; > char *link = NULL; > > if (target) { > if (!link) > return ERR_PTR(-ENOMEM); > } > > Er... That's an odd way to spell > if (target) > return ERR_PTR(-ENOMEM); > (and an odd error value to use). Especially since all callers are passing > NULL as target. > > Why is that code even there, why does that argument still exist and > how many people have actually read that function? > It looks like 1180b4c757aa failed to drop it as part of the patch, but it certainly should have. I can't say why it happened but regardless its an ugly mistake. Thank you very much for catching this Al. A patch to drop it is below or feel free to cons up an alternate version. --- commit 5dbc63d4a0aa819be8ecf21a67a352dd377b0221 Author: John Johansen Date: Tue Sep 24 09:46:33 2019 -0700 apparmor: remove useless aafs_create_symlink 1180b4c757aa ("apparmor: fix dangling symlinks to policy rawdata after replacement") reworked how the rawdata symlink is handled but failed to remove aafs_create_symlink which was reduced to a useless stub . Fixes: 1180b4c757aa ("apparmor: fix dangling symlinks to policy rawdata after replacement") Reported-by: Al Viro Signed-off-by: John Johansen diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c index 9c0e593e30aa..308c99ea3cf8 100644 --- a/security/apparmor/apparmorfs.c +++ b/security/apparmor/apparmorfs.c @@ -335,38 +335,6 @@ static struct dentry *aafs_create_dir(const char *name, struct dentry *parent) NULL); } -/** - * aafs_create_symlink - create a symlink in the apparmorfs filesystem - * @name: name of dentry to create - * @parent: parent directory for this dentry - * @target: if symlink, symlink target string - * @private: private data - * @iops: struct of inode_operations that should be used - * - * If @target parameter is %NULL, then the @iops parameter needs to be - * setup to handle .readlink and .get_link inode_operations. - */ -static struct dentry *aafs_create_symlink(const char *name, - struct dentry *parent, - const char *target, - void *private, - const struct inode_operations *iops) -{ - struct dentry *dent; - char *link = NULL; - - if (target) { - if (!link) - return ERR_PTR(-ENOMEM); - } - dent = aafs_create(name, S_IFLNK | 0444, parent, private, link, NULL, - iops); - if (IS_ERR(dent)) - kfree(link); - - return dent; -} - /** * aafs_remove - removes a file or directory from the apparmorfs filesystem * @@ -1757,25 +1725,25 @@ int __aafs_profile_mkdir(struct aa_profile *profile, struct dentry *parent) } if (profile->rawdata) { - dent = aafs_create_symlink("raw_sha1", dir, NULL, - profile->label.proxy, - &rawdata_link_sha1_iops); + dent = aafs_create("raw_sha1", S_IFLNK | 0444, dir, + profile->label.proxy, NULL, NULL, + &rawdata_link_sha1_iops); if (IS_ERR(dent)) goto fail; aa_get_proxy(profile->label.proxy); profile->dents[AAFS_PROF_RAW_HASH] = dent; - dent = aafs_create_symlink("raw_abi", dir, NULL, - profile->label.proxy, - &rawdata_link_abi_iops); + dent = aafs_create("raw_abi", S_IFLNK | 0444, dir, + profile->label.proxy, NULL, NULL, + &rawdata_link_abi_iops); if (IS_ERR(dent)) goto fail; aa_get_proxy(profile->label.proxy); profile->dents[AAFS_PROF_RAW_ABI] = dent; - dent = aafs_create_symlink("raw_data", dir, NULL, - profile->label.proxy, - &rawdata_link_data_iops); + dent = aafs_create("raw_data", S_IFLNK | 0444, dir, + profile->label.proxy, NULL, NULL, + &rawdata_link_data_iops); if (IS_ERR(dent)) goto fail; aa_get_proxy(profile->label.proxy);