[v7,08/16] LSM: Infrastructure security blobs for mount options

Message ID	20190807224245.10798-10-casey@schaufler-ca.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <linux-security-module-owner@kernel.org> From: Casey Schaufler <casey@schaufler-ca.com> To: casey.schaufler@intel.com, jmorris@namei.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org Cc: casey@schaufler-ca.com, keescook@chromium.org, john.johansen@canonical.com, penguin-kernel@i-love.sakura.ne.jp, paul@paul-moore.com, sds@tycho.nsa.gov Subject: [PATCH v7 08/16] LSM: Infrastructure security blobs for mount options Date: Wed, 7 Aug 2019 15:42:37 -0700 Message-Id: <20190807224245.10798-10-casey@schaufler-ca.com> In-Reply-To: <20190807224245.10798-1-casey@schaufler-ca.com> References: <20190807224245.10798-1-casey@schaufler-ca.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk
Series	LSM: Full module stacking \| expand [v7,00/16] LSM: Full module stacking [v7,01/16] LSM: Single hook called in secmark refcounting [v7,02/16] Smack: Detect if secmarks can be safely used [v7,03/16] LSM: Support multiple LSMs using inode_init_security [v7,04/16] LSM: List multiple security attributes in security_inode_listsecurity [v7,05/16] LSM: Multiple modules using security_ismaclabel [v7,06/16] LSM: Make multiple MAC modules safe in nfs and kernfs [v7,07/16] LSM: Correct handling of ENOSYS in inode_setxattr [v7,08/16] LSM: Infrastructure security blobs for mount options [v7,09/16] LSM: Fix for security_init_inode_security [v7,10/16] LSM: Change error detection for UDP peer security [v7,11/16] Netlabel: Add a secattr comparison API function [v7,12/16] Netlabel: Provide labeling type to security modules [v7,13/16] LSM: Remember the NLTYPE of netlabel sockets [v7,14/16] LSM: Hook for netlabel reconciliation [v7,15/16] LSM: Avoid network conflicts in SELinux and Smack [v7,16/16] Smack: Remove the exclusive flag

diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index b0f788bf82b6..a54a2f4788af 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -2060,6 +2060,7 @@ struct lsm_blob_sizes { int lbs_key; int lbs_msg_msg; int lbs_task; + int lbs_mnt_opts; }; /* @@ -2148,4 +2149,8 @@ static inline int lsm_task_display(struct task_struct *task) return LSMBLOB_INVALID; } +#ifdef CONFIG_SECURITY +void *lsm_mnt_opts_alloc(void); +#endif + #endif /* ! __LINUX_LSM_HOOKS_H */ diff --git a/security/security.c b/security/security.c index e3ea48c87dba..6dbc7ed2a00d 100644 --- a/security/security.c +++ b/security/security.c @@ -183,6 +183,7 @@ static void __init lsm_set_blob_sizes(struct lsm_blob_sizes *needed) #ifdef CONFIG_KEYS lsm_set_blob_size(&needed->lbs_key, &blob_sizes.lbs_key); #endif + lsm_set_blob_size(&needed->lbs_mnt_opts, &blob_sizes.lbs_mnt_opts); lsm_set_blob_size(&needed->lbs_msg_msg, &blob_sizes.lbs_msg_msg); lsm_set_blob_size(&needed->lbs_sock, &blob_sizes.lbs_sock); lsm_set_blob_size(&needed->lbs_superblock, &blob_sizes.lbs_superblock); @@ -321,6 +322,7 @@ static void __init ordered_lsm_init(void) #ifdef CONFIG_KEYS init_debug("key blob size = %d\n", blob_sizes.lbs_key); #endif /* CONFIG_KEYS */ + init_debug("mnt_opts blob size = %d\n", blob_sizes.lbs_mnt_opts); init_debug("msg_msg blob size = %d\n", blob_sizes.lbs_msg_msg); init_debug("sock blob size = %d\n", blob_sizes.lbs_sock); init_debug("superblock blob size = %d\n", blob_sizes.lbs_superblock); @@ -779,6 +781,21 @@ static int append_ctx(char **ctx, int *ctxlen, const char *lsm, char *new, return 0; } +/** + * lsm_mnt_opts_alloc - allocate a composite mnt_opts blob + * + * Allocate the mount options blob + * + * Returns the blob, or NULL if memory can't be allocated. + */ +void *lsm_mnt_opts_alloc(void) +{ + if (blob_sizes.lbs_mnt_opts == 0) + return NULL; + + return kzalloc(blob_sizes.lbs_mnt_opts, GFP_KERNEL); +} + /* * Hook list operation macros. * @@ -974,6 +991,7 @@ void security_free_mnt_opts(void **mnt_opts) if (!*mnt_opts) return; call_void_hook(sb_free_mnt_opts, *mnt_opts); + kfree(*mnt_opts); *mnt_opts = NULL; } EXPORT_SYMBOL(security_free_mnt_opts); diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 021694b4aca7..65bd62dca9e9 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -383,14 +383,20 @@ struct selinux_mnt_opts { const char *fscontext, *context, *rootcontext, *defcontext; }; +static void *selinux_mnt_opts(void *mnt_opts) +{ + if (mnt_opts) + return mnt_opts + selinux_blob_sizes.lbs_mnt_opts; + return NULL; +} + static void selinux_free_mnt_opts(void *mnt_opts) { - struct selinux_mnt_opts *opts = mnt_opts; + struct selinux_mnt_opts *opts = selinux_mnt_opts(mnt_opts); kfree(opts->fscontext); kfree(opts->context); kfree(opts->rootcontext); kfree(opts->defcontext); - kfree(opts); } static inline int inode_doinit(struct inode *inode) @@ -638,7 +644,7 @@ static int selinux_set_mnt_opts(struct super_block *sb, const struct cred *cred = current_cred(); struct superblock_security_struct *sbsec = selinux_superblock(sb); struct dentry *root = sbsec->sb->s_root; - struct selinux_mnt_opts *opts = mnt_opts; + struct selinux_mnt_opts *opts = selinux_mnt_opts(mnt_opts); struct inode_security_struct *root_isec; u32 fscontext_sid = 0, context_sid = 0, rootcontext_sid = 0; u32 defcontext_sid = 0; @@ -653,7 +659,8 @@ static int selinux_set_mnt_opts(struct super_block *sb, server is ready to handle calls. */ goto out; } - rc = -EINVAL; + /* Don't set any SELinux options. Allow any other LSM + that's on the stack to do so. */ pr_warn("SELinux: Unable to set superblock options " "before the security server is initialized\n"); goto out; @@ -980,16 +987,17 @@ static int selinux_sb_clone_mnt_opts(const struct super_block *oldsb, static int selinux_add_opt(int token, const char *s, void **mnt_opts) { - struct selinux_mnt_opts *opts = *mnt_opts; + struct selinux_mnt_opts *opts = selinux_mnt_opts(*mnt_opts); if (token == Opt_seclabel) /* eaten and completely ignored */ return 0; if (!opts) { - opts = kzalloc(sizeof(struct selinux_mnt_opts), GFP_KERNEL); + opts = lsm_mnt_opts_alloc(); if (!opts) return -ENOMEM; *mnt_opts = opts; + opts = selinux_mnt_opts(opts); } if (!s) return -ENOMEM; @@ -1042,10 +1050,8 @@ static int selinux_add_mnt_opt(const char *option, const char *val, int len, rc = selinux_add_opt(token, val, mnt_opts); if (unlikely(rc)) { kfree(val); - if (*mnt_opts) { + if (*mnt_opts) selinux_free_mnt_opts(*mnt_opts); - *mnt_opts = NULL; - } } return rc; } @@ -2645,10 +2651,8 @@ static int selinux_sb_eat_lsm_opts(char *options, void **mnt_opts) rc = selinux_add_opt(token, arg, mnt_opts); if (unlikely(rc)) { kfree(arg); - if (*mnt_opts) { + if (*mnt_opts) selinux_free_mnt_opts(*mnt_opts); - *mnt_opts = NULL; - } return rc; } } else { @@ -2671,7 +2675,7 @@ static int selinux_sb_eat_lsm_opts(char *options, void **mnt_opts) static int selinux_sb_remount(struct super_block *sb, void *mnt_opts) { - struct selinux_mnt_opts *opts = mnt_opts; + struct selinux_mnt_opts *opts = selinux_mnt_opts(mnt_opts); struct superblock_security_struct *sbsec = selinux_superblock(sb); u32 sid; int rc; @@ -6640,6 +6644,7 @@ struct lsm_blob_sizes selinux_blob_sizes __lsm_ro_after_init = { #ifdef CONFIG_KEYS .lbs_key = sizeof(struct key_security_struct), #endif /* CONFIG_KEYS */ + .lbs_mnt_opts = sizeof(struct selinux_mnt_opts), .lbs_msg_msg = sizeof(struct msg_security_struct), .lbs_sock = sizeof(struct sk_security_struct), .lbs_superblock = sizeof(struct superblock_security_struct), diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index f253d569dee6..a9fb5f53a248 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -557,26 +557,33 @@ struct smack_mnt_opts { const char *fsdefault, *fsfloor, *fshat, *fsroot, *fstransmute; }; +static void *smack_mnt_opts(void *opts) +{ + if (opts) + return opts + smack_blob_sizes.lbs_mnt_opts; + return NULL; +} + static void smack_free_mnt_opts(void *mnt_opts) { - struct smack_mnt_opts *opts = mnt_opts; + struct smack_mnt_opts *opts = smack_mnt_opts(mnt_opts); kfree(opts->fsdefault); kfree(opts->fsfloor); kfree(opts->fshat); kfree(opts->fsroot); kfree(opts->fstransmute); - kfree(opts); } static int smack_add_opt(int token, const char *s, void **mnt_opts) { - struct smack_mnt_opts *opts = *mnt_opts; + struct smack_mnt_opts *opts = smack_mnt_opts(*mnt_opts); if (!opts) { - opts = kzalloc(sizeof(struct smack_mnt_opts), GFP_KERNEL); + opts = lsm_mnt_opts_alloc(); if (!opts) return -ENOMEM; *mnt_opts = opts; + opts = smack_mnt_opts(opts); } if (!s) return -ENOMEM; @@ -724,7 +731,6 @@ static int smack_sb_eat_lsm_opts(char *options, void **mnt_opts) kfree(arg); if (*mnt_opts) smack_free_mnt_opts(*mnt_opts); - *mnt_opts = NULL; return rc; } } else { @@ -767,7 +773,7 @@ static int smack_set_mnt_opts(struct super_block *sb, struct superblock_smack *sp = smack_superblock(sb); struct inode_smack *isp; struct smack_known *skp; - struct smack_mnt_opts *opts = mnt_opts; + struct smack_mnt_opts *opts = smack_mnt_opts(mnt_opts); bool transmute = false; if (sp->smk_flags & SMK_SB_INITIALIZED) @@ -4561,6 +4567,7 @@ struct lsm_blob_sizes smack_blob_sizes __lsm_ro_after_init = { #ifdef CONFIG_KEYS .lbs_key = sizeof(struct smack_known *), #endif /* CONFIG_KEYS */ + .lbs_mnt_opts = sizeof(struct smack_mnt_opts), .lbs_msg_msg = sizeof(struct smack_known *), .lbs_sock = sizeof(struct socket_smack), .lbs_superblock = sizeof(struct superblock_smack),

[v7,08/16] LSM: Infrastructure security blobs for mount options

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