From: Roberto Sassu <roberto.sassu@huawei.com> To: <zohar@linux.ibm.com>, <jmorris@namei.org>, <paul@paul-moore.com>, <casey@schaufler-ca.com> Cc: <linux-integrity@vger.kernel.org>, <linux-security-module@vger.kernel.org>, <linux-kernel@vger.kernel.org>, <selinux@vger.kernel.org>, <reiserfs-devel@vger.kernel.org>, Roberto Sassu <roberto.sassu@huawei.com> Subject: [PATCH v2 4/6] security: Support multiple LSMs implementing the inode_init_security hook Date: Wed, 21 Apr 2021 18:19:23 +0200 [thread overview] Message-ID: <20210421161925.968825-5-roberto.sassu@huawei.com> (raw) In-Reply-To: <20210421161925.968825-1-roberto.sassu@huawei.com> The current implementation of security_inode_init_security() is capable of handling only one LSM providing an xattr to be set at inode creation. That xattr is then passed to EVM to calculate the HMAC. To support multiple LSMs, each providing an xattr, this patch makes the following modifications: security_inode_init_security(): - dynamically allocates new_xattrs, based on the number of inode_init_security hooks registered by LSMs; - replaces the call_int_hook() macro with its definition, to correctly handle the case of an LSM returning -EOPNOTSUPP (the loop should not be stopped). security_old_inode_init_security(): - replaces the call_int_hook() macro with its definition, to stop the loop at the first LSM providing an xattr, to avoid a memory leak (due to overwriting the *value pointer). The modifications necessary for EVM to calculate the HMAC on all xattrs will be done in a separate patch. Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> --- security/security.c | 93 +++++++++++++++++++++++++++++++++++++++------ 1 file changed, 82 insertions(+), 11 deletions(-) diff --git a/security/security.c b/security/security.c index 2c1fe1496069..2ab67fa4422e 100644 --- a/security/security.c +++ b/security/security.c @@ -30,8 +30,6 @@ #include <linux/msg.h> #include <net/flow.h> -#define MAX_LSM_EVM_XATTR 2 - /* How many LSMs were built into the kernel? */ #define LSM_COUNT (__end_lsm_info - __start_lsm_info) @@ -1028,9 +1026,10 @@ int security_inode_init_security(struct inode *inode, struct inode *dir, const struct qstr *qstr, const initxattrs initxattrs, void *fs_data) { - struct xattr new_xattrs[MAX_LSM_EVM_XATTR + 1]; + struct xattr *new_xattrs; struct xattr *lsm_xattr, *evm_xattr, *xattr; - int ret; + struct security_hook_list *P; + int ret, max_new_xattrs = 0; if (unlikely(IS_PRIVATE(inode))) return 0; @@ -1038,14 +1037,52 @@ int security_inode_init_security(struct inode *inode, struct inode *dir, if (!initxattrs) return call_int_hook(inode_init_security, -EOPNOTSUPP, inode, dir, qstr, NULL, fs_data); - memset(new_xattrs, 0, sizeof(new_xattrs)); + + /* Determine at run-time the max number of xattr structs to allocate. */ + hlist_for_each_entry(P, &security_hook_heads.inode_init_security, list) + max_new_xattrs++; + + if (!max_new_xattrs) + return 0; + + /* Allocate +1 for EVM and +1 as terminator. */ + new_xattrs = kcalloc(max_new_xattrs + 2, sizeof(*new_xattrs), GFP_NOFS); + if (!new_xattrs) + return -ENOMEM; + lsm_xattr = new_xattrs; - ret = call_int_hook(inode_init_security, -EOPNOTSUPP, inode, dir, qstr, - lsm_xattr, fs_data); - if (ret) + hlist_for_each_entry(P, &security_hook_heads.inode_init_security, + list) { + ret = P->hook.inode_init_security(inode, dir, qstr, new_xattrs, + fs_data); + if (ret) { + if (ret != -EOPNOTSUPP) + goto out; + + continue; + } + + /* LSM implementation error. */ + if (lsm_xattr->name == NULL || lsm_xattr->value == NULL) { + WARN_ONCE( + "LSM %s: ret = 0 but xattr name/value = NULL\n", + P->lsm); + ret = -ENOENT; + goto out; + } + + lsm_xattr++; + + if (!--max_new_xattrs) + break; + } + + if (!new_xattrs->name) { + ret = -EOPNOTSUPP; goto out; + } - evm_xattr = lsm_xattr + 1; + evm_xattr = lsm_xattr; ret = evm_inode_init_security(inode, new_xattrs, evm_xattr); if (ret) goto out; @@ -1053,6 +1090,7 @@ int security_inode_init_security(struct inode *inode, struct inode *dir, out: for (xattr = new_xattrs; xattr->value != NULL; xattr++) kfree(xattr->value); + kfree(new_xattrs); return (ret == -EOPNOTSUPP) ? 0 : ret; } EXPORT_SYMBOL(security_inode_init_security); @@ -1071,11 +1109,44 @@ int security_old_inode_init_security(struct inode *inode, struct inode *dir, { struct xattr xattr = { .name = NULL, .value = NULL, .value_len = 0 }; struct xattr *lsm_xattr = (name && value && len) ? &xattr : NULL; + struct security_hook_list *P; + int ret; if (unlikely(IS_PRIVATE(inode))) return -EOPNOTSUPP; - return call_int_hook(inode_init_security, -EOPNOTSUPP, inode, dir, - qstr, lsm_xattr, NULL); + + hlist_for_each_entry(P, &security_hook_heads.inode_init_security, + list) { + ret = P->hook.inode_init_security(inode, dir, qstr, lsm_xattr, + NULL); + if (ret) { + if (ret != -EOPNOTSUPP) + return ret; + + continue; + } + + if (!lsm_xattr) + continue; + + /* LSM implementation error. */ + if (lsm_xattr->name == NULL || lsm_xattr->value == NULL) { + WARN_ONCE( + "LSM %s: ret = 0 but xattr name/value = NULL\n", + P->lsm); + + /* Callers should do the cleanup. */ + return -ENOENT; + } + + *name = lsm_xattr->name; + *value = lsm_xattr->value; + *len = lsm_xattr->value_len; + + return ret; + } + + return -EOPNOTSUPP; } EXPORT_SYMBOL(security_old_inode_init_security); -- 2.25.1
WARNING: multiple messages have this Message-ID (diff)
From: Roberto Sassu <roberto.sassu@huawei.com> To: zohar@linux.ibm.com, jmorris@namei.org, paul@paul-moore.com, casey@schaufler-ca.com Cc: linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, selinux@vger.kernel.org, reiserfs-devel@vger.kernel.org, Roberto Sassu <roberto.sassu@huawei.com> Subject: [PATCH v2 4/6] security: Support multiple LSMs implementing the inode_init_security hook Date: Wed, 21 Apr 2021 18:19:23 +0200 [thread overview] Message-ID: <20210421161925.968825-5-roberto.sassu@huawei.com> (raw) In-Reply-To: <20210421161925.968825-1-roberto.sassu@huawei.com> The current implementation of security_inode_init_security() is capable of handling only one LSM providing an xattr to be set at inode creation. That xattr is then passed to EVM to calculate the HMAC. To support multiple LSMs, each providing an xattr, this patch makes the following modifications: security_inode_init_security(): - dynamically allocates new_xattrs, based on the number of inode_init_security hooks registered by LSMs; - replaces the call_int_hook() macro with its definition, to correctly handle the case of an LSM returning -EOPNOTSUPP (the loop should not be stopped). security_old_inode_init_security(): - replaces the call_int_hook() macro with its definition, to stop the loop at the first LSM providing an xattr, to avoid a memory leak (due to overwriting the *value pointer). The modifications necessary for EVM to calculate the HMAC on all xattrs will be done in a separate patch. Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> --- security/security.c | 93 +++++++++++++++++++++++++++++++++++++++------ 1 file changed, 82 insertions(+), 11 deletions(-) diff --git a/security/security.c b/security/security.c index 2c1fe1496069..2ab67fa4422e 100644 --- a/security/security.c +++ b/security/security.c @@ -30,8 +30,6 @@ #include <linux/msg.h> #include <net/flow.h> -#define MAX_LSM_EVM_XATTR 2 - /* How many LSMs were built into the kernel? */ #define LSM_COUNT (__end_lsm_info - __start_lsm_info) @@ -1028,9 +1026,10 @@ int security_inode_init_security(struct inode *inode, struct inode *dir, const struct qstr *qstr, const initxattrs initxattrs, void *fs_data) { - struct xattr new_xattrs[MAX_LSM_EVM_XATTR + 1]; + struct xattr *new_xattrs; struct xattr *lsm_xattr, *evm_xattr, *xattr; - int ret; + struct security_hook_list *P; + int ret, max_new_xattrs = 0; if (unlikely(IS_PRIVATE(inode))) return 0; @@ -1038,14 +1037,52 @@ int security_inode_init_security(struct inode *inode, struct inode *dir, if (!initxattrs) return call_int_hook(inode_init_security, -EOPNOTSUPP, inode, dir, qstr, NULL, fs_data); - memset(new_xattrs, 0, sizeof(new_xattrs)); + + /* Determine at run-time the max number of xattr structs to allocate. */ + hlist_for_each_entry(P, &security_hook_heads.inode_init_security, list) + max_new_xattrs++; + + if (!max_new_xattrs) + return 0; + + /* Allocate +1 for EVM and +1 as terminator. */ + new_xattrs = kcalloc(max_new_xattrs + 2, sizeof(*new_xattrs), GFP_NOFS); + if (!new_xattrs) + return -ENOMEM; + lsm_xattr = new_xattrs; - ret = call_int_hook(inode_init_security, -EOPNOTSUPP, inode, dir, qstr, - lsm_xattr, fs_data); - if (ret) + hlist_for_each_entry(P, &security_hook_heads.inode_init_security, + list) { + ret = P->hook.inode_init_security(inode, dir, qstr, new_xattrs, + fs_data); + if (ret) { + if (ret != -EOPNOTSUPP) + goto out; + + continue; + } + + /* LSM implementation error. */ + if (lsm_xattr->name == NULL || lsm_xattr->value == NULL) { + WARN_ONCE( + "LSM %s: ret = 0 but xattr name/value = NULL\n", + P->lsm); + ret = -ENOENT; + goto out; + } + + lsm_xattr++; + + if (!--max_new_xattrs) + break; + } + + if (!new_xattrs->name) { + ret = -EOPNOTSUPP; goto out; + } - evm_xattr = lsm_xattr + 1; + evm_xattr = lsm_xattr; ret = evm_inode_init_security(inode, new_xattrs, evm_xattr); if (ret) goto out; @@ -1053,6 +1090,7 @@ int security_inode_init_security(struct inode *inode, struct inode *dir, out: for (xattr = new_xattrs; xattr->value != NULL; xattr++) kfree(xattr->value); + kfree(new_xattrs); return (ret == -EOPNOTSUPP) ? 0 : ret; } EXPORT_SYMBOL(security_inode_init_security); @@ -1071,11 +1109,44 @@ int security_old_inode_init_security(struct inode *inode, struct inode *dir, { struct xattr xattr = { .name = NULL, .value = NULL, .value_len = 0 }; struct xattr *lsm_xattr = (name && value && len) ? &xattr : NULL; + struct security_hook_list *P; + int ret; if (unlikely(IS_PRIVATE(inode))) return -EOPNOTSUPP; - return call_int_hook(inode_init_security, -EOPNOTSUPP, inode, dir, - qstr, lsm_xattr, NULL); + + hlist_for_each_entry(P, &security_hook_heads.inode_init_security, + list) { + ret = P->hook.inode_init_security(inode, dir, qstr, lsm_xattr, + NULL); + if (ret) { + if (ret != -EOPNOTSUPP) + return ret; + + continue; + } + + if (!lsm_xattr) + continue; + + /* LSM implementation error. */ + if (lsm_xattr->name == NULL || lsm_xattr->value == NULL) { + WARN_ONCE( + "LSM %s: ret = 0 but xattr name/value = NULL\n", + P->lsm); + + /* Callers should do the cleanup. */ + return -ENOENT; + } + + *name = lsm_xattr->name; + *value = lsm_xattr->value; + *len = lsm_xattr->value_len; + + return ret; + } + + return -EOPNOTSUPP; } EXPORT_SYMBOL(security_old_inode_init_security); -- 2.25.1
next prev parent reply other threads:[~2021-04-21 16:20 UTC|newest] Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-04-21 16:19 [PATCH v2 0/6] evm: Prepare for moving to the LSM infrastructure Roberto Sassu 2021-04-21 16:19 ` Roberto Sassu 2021-04-21 16:19 ` [PATCH v2 1/6] xattr: Complete constify ->name member of "struct xattr" Roberto Sassu 2021-04-21 16:19 ` Roberto Sassu 2021-04-21 16:19 ` [PATCH v2 2/6] reiserfs: Add missing calls to reiserfs_security_free() Roberto Sassu 2021-04-21 16:19 ` Roberto Sassu 2021-04-21 16:19 ` [PATCH v2 3/6] security: Pass xattrs allocated by LSMs to the inode_init_security hook Roberto Sassu 2021-04-21 16:19 ` Roberto Sassu 2021-04-21 22:43 ` Casey Schaufler 2021-04-22 13:46 ` Roberto Sassu 2021-04-22 15:46 ` Casey Schaufler 2021-04-22 16:12 ` Roberto Sassu 2021-04-22 21:39 ` Casey Schaufler 2021-04-21 16:19 ` Roberto Sassu [this message] 2021-04-21 16:19 ` [PATCH v2 4/6] security: Support multiple LSMs implementing " Roberto Sassu 2021-04-21 23:09 ` Casey Schaufler 2021-04-21 16:19 ` [PATCH v2 5/6] evm: Align evm_inode_init_security() definition with LSM infrastructure Roberto Sassu 2021-04-21 16:19 ` Roberto Sassu 2021-04-21 16:19 ` [PATCH v2 6/6] evm: Support multiple LSMs providing an xattr Roberto Sassu 2021-04-21 16:19 ` Roberto Sassu
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