From 3486740a4f32a6a466f5ac931654d154790ba648 Mon Sep 17 00:00:00 2001 From: "Serge E. Hallyn" Date: Wed, 23 Mar 2011 16:43:17 -0700 Subject: userns: security: make capabilities relative to the user namespace - Introduce ns_capable to test for a capability in a non-default user namespace. - Teach cap_capable to handle capabilities in a non-default user namespace. The motivation is to get to the unprivileged creation of new namespaces. It looks like this gets us 90% of the way there, with only potential uid confusion issues left. I still need to handle getting all caps after creation but otherwise I think I have a good starter patch that achieves all of your goals. Changelog: 11/05/2010: [serge] add apparmor 12/14/2010: [serge] fix capabilities to created user namespaces Without this, if user serge creates a user_ns, he won't have capabilities to the user_ns he created. THis is because we were first checking whether his effective caps had the caps he needed and returning -EPERM if not, and THEN checking whether he was the creator. Reverse those checks. 12/16/2010: [serge] security_real_capable needs ns argument in !security case 01/11/2011: [serge] add task_ns_capable helper 01/11/2011: [serge] add nsown_capable() helper per Bastian Blank suggestion 02/16/2011: [serge] fix a logic bug: the root user is always creator of init_user_ns, but should not always have capabilities to it! Fix the check in cap_capable(). 02/21/2011: Add the required user_ns parameter to security_capable, fixing a compile failure. 02/23/2011: Convert some macros to functions as per akpm comments. Some couldn't be converted because we can't easily forward-declare them (they are inline if !SECURITY, extern if SECURITY). Add a current_user_ns function so we can use it in capability.h without #including cred.h. Move all forward declarations together to the top of the #ifdef __KERNEL__ section, and use kernel-doc format. 02/23/2011: Per dhowells, clean up comment in cap_capable(). 02/23/2011: Per akpm, remove unreachable 'return -EPERM' in cap_capable. (Original written and signed off by Eric; latest, modified version acked by him) [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: export current_user_ns() for ecryptfs] [serge.hallyn@canonical.com: remove unneeded extra argument in selinux's task_has_capability] Signed-off-by: Eric W. Biederman Signed-off-by: Serge E. Hallyn Acked-by: "Eric W. Biederman" Acked-by: Daniel Lezcano Acked-by: David Howells Cc: James Morris Signed-off-by: Serge E. Hallyn Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- security/apparmor/lsm.c | 5 +++-- security/commoncap.c | 38 +++++++++++++++++++++++++++++++------- security/security.c | 16 ++++++++++------ security/selinux/hooks.c | 13 ++++++++----- 4 files changed, 52 insertions(+), 20 deletions(-) (limited to 'security') diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c index d21a427..ae3a698 100644 --- a/security/apparmor/lsm.c +++ b/security/apparmor/lsm.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include "include/apparmor.h" @@ -136,11 +137,11 @@ static int apparmor_capget(struct task_struct *target, kernel_cap_t *effective, } static int apparmor_capable(struct task_struct *task, const struct cred *cred, - int cap, int audit) + struct user_namespace *ns, int cap, int audit) { struct aa_profile *profile; /* cap_capable returns 0 on success, else -EPERM */ - int error = cap_capable(task, cred, cap, audit); + int error = cap_capable(task, cred, ns, cap, audit); if (!error) { profile = aa_cred_profile(cred); if (!unconfined(profile)) diff --git a/security/commoncap.c b/security/commoncap.c index 49c57fd..43a205b 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -27,6 +27,7 @@ #include #include #include +#include /* * If a non-root user executes a setuid-root binary in @@ -67,6 +68,7 @@ EXPORT_SYMBOL(cap_netlink_recv); * cap_capable - Determine whether a task has a particular effective capability * @tsk: The task to query * @cred: The credentials to use + * @ns: The user namespace in which we need the capability * @cap: The capability to check for * @audit: Whether to write an audit message or not * @@ -78,10 +80,30 @@ EXPORT_SYMBOL(cap_netlink_recv); * cap_has_capability() returns 0 when a task has a capability, but the * kernel's capable() and has_capability() returns 1 for this case. */ -int cap_capable(struct task_struct *tsk, const struct cred *cred, int cap, - int audit) +int cap_capable(struct task_struct *tsk, const struct cred *cred, + struct user_namespace *targ_ns, int cap, int audit) { - return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM; + for (;;) { + /* The creator of the user namespace has all caps. */ + if (targ_ns != &init_user_ns && targ_ns->creator == cred->user) + return 0; + + /* Do we have the necessary capabilities? */ + if (targ_ns == cred->user->user_ns) + return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM; + + /* Have we tried all of the parent namespaces? */ + if (targ_ns == &init_user_ns) + return -EPERM; + + /* + *If you have a capability in a parent user ns, then you have + * it over all children user namespaces as well. + */ + targ_ns = targ_ns->creator->user_ns; + } + + /* We never get here */ } /** @@ -176,7 +198,8 @@ static inline int cap_inh_is_capped(void) /* they are so limited unless the current task has the CAP_SETPCAP * capability */ - if (cap_capable(current, current_cred(), CAP_SETPCAP, + if (cap_capable(current, current_cred(), + current_cred()->user->user_ns, CAP_SETPCAP, SECURITY_CAP_AUDIT) == 0) return 0; return 1; @@ -828,7 +851,8 @@ int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3, & (new->securebits ^ arg2)) /*[1]*/ || ((new->securebits & SECURE_ALL_LOCKS & ~arg2)) /*[2]*/ || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/ - || (cap_capable(current, current_cred(), CAP_SETPCAP, + || (cap_capable(current, current_cred(), + current_cred()->user->user_ns, CAP_SETPCAP, SECURITY_CAP_AUDIT) != 0) /*[4]*/ /* * [1] no changing of bits that are locked @@ -893,7 +917,7 @@ int cap_vm_enough_memory(struct mm_struct *mm, long pages) { int cap_sys_admin = 0; - if (cap_capable(current, current_cred(), CAP_SYS_ADMIN, + if (cap_capable(current, current_cred(), &init_user_ns, CAP_SYS_ADMIN, SECURITY_CAP_NOAUDIT) == 0) cap_sys_admin = 1; return __vm_enough_memory(mm, pages, cap_sys_admin); @@ -920,7 +944,7 @@ int cap_file_mmap(struct file *file, unsigned long reqprot, int ret = 0; if (addr < dac_mmap_min_addr) { - ret = cap_capable(current, current_cred(), CAP_SYS_RAWIO, + ret = cap_capable(current, current_cred(), &init_user_ns, CAP_SYS_RAWIO, SECURITY_CAP_AUDIT); /* set PF_SUPERPRIV if it turns out we allow the low mmap */ if (ret == 0) diff --git a/security/security.c b/security/security.c index 9187665..1011423 100644 --- a/security/security.c +++ b/security/security.c @@ -154,29 +154,33 @@ int security_capset(struct cred *new, const struct cred *old, effective, inheritable, permitted); } -int security_capable(const struct cred *cred, int cap) +int security_capable(struct user_namespace *ns, const struct cred *cred, + int cap) { - return security_ops->capable(current, cred, cap, SECURITY_CAP_AUDIT); + return security_ops->capable(current, cred, ns, cap, + SECURITY_CAP_AUDIT); } -int security_real_capable(struct task_struct *tsk, int cap) +int security_real_capable(struct task_struct *tsk, struct user_namespace *ns, + int cap) { const struct cred *cred; int ret; cred = get_task_cred(tsk); - ret = security_ops->capable(tsk, cred, cap, SECURITY_CAP_AUDIT); + ret = security_ops->capable(tsk, cred, ns, cap, SECURITY_CAP_AUDIT); put_cred(cred); return ret; } -int security_real_capable_noaudit(struct task_struct *tsk, int cap) +int security_real_capable_noaudit(struct task_struct *tsk, + struct user_namespace *ns, int cap) { const struct cred *cred; int ret; cred = get_task_cred(tsk); - ret = security_ops->capable(tsk, cred, cap, SECURITY_CAP_NOAUDIT); + ret = security_ops->capable(tsk, cred, ns, cap, SECURITY_CAP_NOAUDIT); put_cred(cred); return ret; } diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 6475e1f..c67f863 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -79,6 +79,7 @@ #include #include #include +#include #include "avc.h" #include "objsec.h" @@ -1846,11 +1847,11 @@ static int selinux_capset(struct cred *new, const struct cred *old, */ static int selinux_capable(struct task_struct *tsk, const struct cred *cred, - int cap, int audit) + struct user_namespace *ns, int cap, int audit) { int rc; - rc = cap_capable(tsk, cred, cap, audit); + rc = cap_capable(tsk, cred, ns, cap, audit); if (rc) return rc; @@ -1931,7 +1932,8 @@ static int selinux_vm_enough_memory(struct mm_struct *mm, long pages) { int rc, cap_sys_admin = 0; - rc = selinux_capable(current, current_cred(), CAP_SYS_ADMIN, + rc = selinux_capable(current, current_cred(), + &init_user_ns, CAP_SYS_ADMIN, SECURITY_CAP_NOAUDIT); if (rc == 0) cap_sys_admin = 1; @@ -2834,7 +2836,8 @@ static int selinux_inode_getsecurity(const struct inode *inode, const char *name * and lack of permission just means that we fall back to the * in-core context value, not a denial. */ - error = selinux_capable(current, current_cred(), CAP_MAC_ADMIN, + error = selinux_capable(current, current_cred(), + &init_user_ns, CAP_MAC_ADMIN, SECURITY_CAP_NOAUDIT); if (!error) error = security_sid_to_context_force(isec->sid, &context, @@ -2968,7 +2971,7 @@ static int selinux_file_ioctl(struct file *file, unsigned int cmd, case KDSKBENT: case KDSKBSENT: error = task_has_capability(current, cred, CAP_SYS_TTY_CONFIG, - SECURITY_CAP_AUDIT); + SECURITY_CAP_AUDIT); break; /* default case assumes that the command will go -- cgit v1.1 From 8409cca7056113bee3236cb6a8e4d8d4d1eef102 Mon Sep 17 00:00:00 2001 From: "Serge E. Hallyn" Date: Wed, 23 Mar 2011 16:43:20 -0700 Subject: userns: allow ptrace from non-init user namespaces ptrace is allowed to tasks in the same user namespace according to the usual rules (i.e. the same rules as for two tasks in the init user namespace). ptrace is also allowed to a user namespace to which the current task the has CAP_SYS_PTRACE capability. Changelog: Dec 31: Address feedback by Eric: . Correct ptrace uid check . Rename may_ptrace_ns to ptrace_capable . Also fix the cap_ptrace checks. Jan 1: Use const cred struct Jan 11: use task_ns_capable() in place of ptrace_capable(). Feb 23: same_or_ancestore_user_ns() was not an appropriate check to constrain cap_issubset. Rather, cap_issubset() only is meaningful when both capsets are in the same user_ns. Signed-off-by: Serge E. Hallyn Cc: "Eric W. Biederman" Acked-by: Daniel Lezcano Acked-by: David Howells Cc: James Morris Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- security/commoncap.c | 40 ++++++++++++++++++++++++++++++++-------- 1 file changed, 32 insertions(+), 8 deletions(-) (limited to 'security') diff --git a/security/commoncap.c b/security/commoncap.c index 43a205b..f20e984 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -127,18 +127,30 @@ int cap_settime(const struct timespec *ts, const struct timezone *tz) * @child: The process to be accessed * @mode: The mode of attachment. * + * If we are in the same or an ancestor user_ns and have all the target + * task's capabilities, then ptrace access is allowed. + * If we have the ptrace capability to the target user_ns, then ptrace + * access is allowed. + * Else denied. + * * Determine whether a process may access another, returning 0 if permission * granted, -ve if denied. */ int cap_ptrace_access_check(struct task_struct *child, unsigned int mode) { int ret = 0; + const struct cred *cred, *child_cred; rcu_read_lock(); - if (!cap_issubset(__task_cred(child)->cap_permitted, - current_cred()->cap_permitted) && - !capable(CAP_SYS_PTRACE)) - ret = -EPERM; + cred = current_cred(); + child_cred = __task_cred(child); + if (cred->user->user_ns == child_cred->user->user_ns && + cap_issubset(child_cred->cap_permitted, cred->cap_permitted)) + goto out; + if (ns_capable(child_cred->user->user_ns, CAP_SYS_PTRACE)) + goto out; + ret = -EPERM; +out: rcu_read_unlock(); return ret; } @@ -147,18 +159,30 @@ int cap_ptrace_access_check(struct task_struct *child, unsigned int mode) * cap_ptrace_traceme - Determine whether another process may trace the current * @parent: The task proposed to be the tracer * + * If parent is in the same or an ancestor user_ns and has all current's + * capabilities, then ptrace access is allowed. + * If parent has the ptrace capability to current's user_ns, then ptrace + * access is allowed. + * Else denied. + * * Determine whether the nominated task is permitted to trace the current * process, returning 0 if permission is granted, -ve if denied. */ int cap_ptrace_traceme(struct task_struct *parent) { int ret = 0; + const struct cred *cred, *child_cred; rcu_read_lock(); - if (!cap_issubset(current_cred()->cap_permitted, - __task_cred(parent)->cap_permitted) && - !has_capability(parent, CAP_SYS_PTRACE)) - ret = -EPERM; + cred = __task_cred(parent); + child_cred = current_cred(); + if (cred->user->user_ns == child_cred->user->user_ns && + cap_issubset(child_cred->cap_permitted, cred->cap_permitted)) + goto out; + if (has_ns_capability(parent, child_cred->user->user_ns, CAP_SYS_PTRACE)) + goto out; + ret = -EPERM; +out: rcu_read_unlock(); return ret; } -- cgit v1.1 From 2e1496707560ecf98e9b0604622c0990f94861d3 Mon Sep 17 00:00:00 2001 From: "Serge E. Hallyn" Date: Wed, 23 Mar 2011 16:43:26 -0700 Subject: userns: rename is_owner_or_cap to inode_owner_or_capable And give it a kernel-doc comment. [akpm@linux-foundation.org: btrfs changed in linux-next] Signed-off-by: Serge E. Hallyn Cc: "Eric W. Biederman" Cc: Daniel Lezcano Acked-by: David Howells Cc: James Morris Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- security/selinux/hooks.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'security') diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index c67f863..f9c3764 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2725,7 +2725,7 @@ static int selinux_inode_setxattr(struct dentry *dentry, const char *name, if (!(sbsec->flags & SE_SBLABELSUPP)) return -EOPNOTSUPP; - if (!is_owner_or_cap(inode)) + if (!inode_owner_or_capable(inode)) return -EPERM; COMMON_AUDIT_DATA_INIT(&ad, FS); -- cgit v1.1 From 85cd6da53a8073d3f4503f56e4ea6cddccbb1c7f Mon Sep 17 00:00:00 2001 From: Stephen Smalley Date: Fri, 25 Mar 2011 10:13:43 -0400 Subject: selinux: Fix regression for Xorg Commit 6f5317e730505d5cbc851c435a2dfe3d5a21d343 introduced a bug in the handling of userspace object classes that is causing breakage for Xorg when XSELinux is enabled. Fix the bug by changing map_class() to return SECCLASS_NULL when the class cannot be mapped to a kernel object class. Reported-by: "Justin P. Mattock" Signed-off-by: Stephen Smalley Signed-off-by: James Morris --- security/selinux/ss/services.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'security') diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c index 3e7544d..ea7c01f 100644 --- a/security/selinux/ss/services.c +++ b/security/selinux/ss/services.c @@ -213,7 +213,7 @@ static u16 map_class(u16 pol_value) return i; } - return pol_value; + return SECCLASS_NULL; } static void map_decision(u16 tclass, struct av_decision *avd, -- cgit v1.1 From 25985edcedea6396277003854657b5f3cb31a628 Mon Sep 17 00:00:00 2001 From: Lucas De Marchi Date: Wed, 30 Mar 2011 22:57:33 -0300 Subject: Fix common misspellings Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi --- security/apparmor/match.c | 2 +- security/apparmor/policy_unpack.c | 2 +- security/selinux/netlabel.c | 2 +- security/selinux/ss/services.c | 4 ++-- security/smack/smack_access.c | 2 +- security/smack/smack_lsm.c | 6 +++--- security/smack/smackfs.c | 6 +++--- security/tomoyo/load_policy.c | 2 +- 8 files changed, 13 insertions(+), 13 deletions(-) (limited to 'security') diff --git a/security/apparmor/match.c b/security/apparmor/match.c index 5cb4dc1..06d764c 100644 --- a/security/apparmor/match.c +++ b/security/apparmor/match.c @@ -195,7 +195,7 @@ void aa_dfa_free_kref(struct kref *kref) * * Unpack a dfa that has been serialized. To find information on the dfa * format look in Documentation/apparmor.txt - * Assumes the dfa @blob stream has been aligned on a 8 byte boundry + * Assumes the dfa @blob stream has been aligned on a 8 byte boundary * * Returns: an unpacked dfa ready for matching or ERR_PTR on failure */ diff --git a/security/apparmor/policy_unpack.c b/security/apparmor/policy_unpack.c index eb3700e..e33aaf7 100644 --- a/security/apparmor/policy_unpack.c +++ b/security/apparmor/policy_unpack.c @@ -359,7 +359,7 @@ fail: * @e: serialized data extent information (NOT NULL) * @profile: profile to add the accept table to (NOT NULL) * - * Returns: 1 if table succesfully unpacked + * Returns: 1 if table successfully unpacked */ static bool unpack_trans_table(struct aa_ext *e, struct aa_profile *profile) { diff --git a/security/selinux/netlabel.c b/security/selinux/netlabel.c index 1c2fc46..c3bf3ed 100644 --- a/security/selinux/netlabel.c +++ b/security/selinux/netlabel.c @@ -151,7 +151,7 @@ void selinux_netlbl_sk_security_free(struct sk_security_struct *sksec) * * Description: * Called when the NetLabel state of a sk_security_struct needs to be reset. - * The caller is responsibile for all the NetLabel sk_security_struct locking. + * The caller is responsible for all the NetLabel sk_security_struct locking. * */ void selinux_netlbl_sk_security_reset(struct sk_security_struct *sksec) diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c index ea7c01f..6ef4af4 100644 --- a/security/selinux/ss/services.c +++ b/security/selinux/ss/services.c @@ -2806,7 +2806,7 @@ int selinux_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule) case AUDIT_SUBJ_CLR: case AUDIT_OBJ_LEV_LOW: case AUDIT_OBJ_LEV_HIGH: - /* we do not allow a range, indicated by the presense of '-' */ + /* we do not allow a range, indicated by the presence of '-' */ if (strchr(rulestr, '-')) return -EINVAL; break; @@ -3075,7 +3075,7 @@ static void security_netlbl_cache_add(struct netlbl_lsm_secattr *secattr, * Description: * Convert the given NetLabel security attributes in @secattr into a * SELinux SID. If the @secattr field does not contain a full SELinux - * SID/context then use SECINITSID_NETMSG as the foundation. If possibile the + * SID/context then use SECINITSID_NETMSG as the foundation. If possible the * 'cache' field of @secattr is set and the CACHE flag is set; this is to * allow the @secattr to be used by NetLabel to cache the secattr to SID * conversion for future lookups. Returns zero on success, negative values on diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c index 86453db..9637e10 100644 --- a/security/smack/smack_access.c +++ b/security/smack/smack_access.c @@ -431,7 +431,7 @@ char *smk_import(const char *string, int len) * smack_from_secid - find the Smack label associated with a secid * @secid: an integer that might be associated with a Smack label * - * Returns a pointer to the appropraite Smack label if there is one, + * Returns a pointer to the appropriate Smack label if there is one, * otherwise a pointer to the invalid Smack label. */ char *smack_from_secid(const u32 secid) diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 23c7a6d..c6f8fca 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -1794,7 +1794,7 @@ static void smack_set_catset(char *catset, struct netlbl_lsm_secattr *sap) * Casey says that CIPSO is good enough for now. * It can be used to effect. * It can also be abused to effect when necessary. - * Appologies to the TSIG group in general and GW in particular. + * Apologies to the TSIG group in general and GW in particular. */ static void smack_to_secattr(char *smack, struct netlbl_lsm_secattr *nlsp) { @@ -2530,7 +2530,7 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode) switch (sbp->s_magic) { case SMACK_MAGIC: /* - * Casey says that it's a little embarassing + * Casey says that it's a little embarrassing * that the smack file system doesn't do * extended attributes. */ @@ -3084,7 +3084,7 @@ static int smack_inet_conn_request(struct sock *sk, struct sk_buff *skb, /* * We need to decide if we want to label the incoming connection here * if we do we only need to label the request_sock and the stack will - * propogate the wire-label to the sock when it is created. + * propagate the wire-label to the sock when it is created. */ hdr = ip_hdr(skb); addr.sin_addr.s_addr = hdr->saddr; diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c index 90d1bba..f934601 100644 --- a/security/smack/smackfs.c +++ b/security/smack/smackfs.c @@ -208,7 +208,7 @@ static ssize_t smk_write_load_list(struct file *file, const char __user *buf, if (*ppos != 0) return -EINVAL; /* - * Minor hack for backward compatability + * Minor hack for backward compatibility */ if (count < (SMK_OLOADLEN) || count > SMK_LOADLEN) return -EINVAL; @@ -223,7 +223,7 @@ static ssize_t smk_write_load_list(struct file *file, const char __user *buf, } /* - * More on the minor hack for backward compatability + * More on the minor hack for backward compatibility */ if (count == (SMK_OLOADLEN)) data[SMK_OLOADLEN] = '-'; @@ -927,7 +927,7 @@ static ssize_t smk_write_netlbladdr(struct file *file, const char __user *buf, } } else { /* we delete the unlabeled entry, only if the previous label - * wasnt the special CIPSO option */ + * wasn't the special CIPSO option */ if (skp->smk_label != smack_cipso_option) rc = netlbl_cfg_unlbl_static_del(&init_net, NULL, &skp->smk_host.sin_addr, &skp->smk_mask, diff --git a/security/tomoyo/load_policy.c b/security/tomoyo/load_policy.c index bbada7c..3312e56 100644 --- a/security/tomoyo/load_policy.c +++ b/security/tomoyo/load_policy.c @@ -23,7 +23,7 @@ static bool tomoyo_policy_loader_exists(void) * If the initrd includes /sbin/init but real-root-dev has not * mounted on / yet, activating MAC will block the system since * policies are not loaded yet. - * Thus, let do_execve() call this function everytime. + * Thus, let do_execve() call this function every time. */ struct path path; -- cgit v1.1 From 8c9e80ed276fc4b9c9fadf29d8bf6b3576112f1a Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Thu, 21 Apr 2011 17:23:19 -0700 Subject: SECURITY: Move exec_permission RCU checks into security modules Right now all RCU walks fall back to reference walk when CONFIG_SECURITY is enabled, even though just the standard capability module is active. This is because security_inode_exec_permission unconditionally fails RCU walks. Move this decision to the low level security module. This requires passing the RCU flags down the security hook. This way at least the capability module and a few easy cases in selinux/smack work with RCU walks with CONFIG_SECURITY=y Signed-off-by: Andi Kleen Acked-by: Eric Paris Signed-off-by: Linus Torvalds --- security/capability.c | 2 +- security/security.c | 6 ++---- security/selinux/hooks.c | 6 +++++- security/smack/smack_lsm.c | 6 +++++- 4 files changed, 13 insertions(+), 7 deletions(-) (limited to 'security') diff --git a/security/capability.c b/security/capability.c index 2984ea4..bbb5115 100644 --- a/security/capability.c +++ b/security/capability.c @@ -181,7 +181,7 @@ static int cap_inode_follow_link(struct dentry *dentry, return 0; } -static int cap_inode_permission(struct inode *inode, int mask) +static int cap_inode_permission(struct inode *inode, int mask, unsigned flags) { return 0; } diff --git a/security/security.c b/security/security.c index 1011423..4ba6d4c 100644 --- a/security/security.c +++ b/security/security.c @@ -518,16 +518,14 @@ int security_inode_permission(struct inode *inode, int mask) { if (unlikely(IS_PRIVATE(inode))) return 0; - return security_ops->inode_permission(inode, mask); + return security_ops->inode_permission(inode, mask, 0); } int security_inode_exec_permission(struct inode *inode, unsigned int flags) { if (unlikely(IS_PRIVATE(inode))) return 0; - if (flags) - return -ECHILD; - return security_ops->inode_permission(inode, MAY_EXEC); + return security_ops->inode_permission(inode, MAY_EXEC, flags); } int security_inode_setattr(struct dentry *dentry, struct iattr *attr) diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index f9c3764..a73f4e4 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2635,7 +2635,7 @@ static int selinux_inode_follow_link(struct dentry *dentry, struct nameidata *na return dentry_has_perm(cred, NULL, dentry, FILE__READ); } -static int selinux_inode_permission(struct inode *inode, int mask) +static int selinux_inode_permission(struct inode *inode, int mask, unsigned flags) { const struct cred *cred = current_cred(); struct common_audit_data ad; @@ -2649,6 +2649,10 @@ static int selinux_inode_permission(struct inode *inode, int mask) if (!mask) return 0; + /* May be droppable after audit */ + if (flags & IPERM_FLAG_RCU) + return -ECHILD; + COMMON_AUDIT_DATA_INIT(&ad, FS); ad.u.fs.inode = inode; diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index c6f8fca..400a5d5 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -686,7 +686,7 @@ static int smack_inode_rename(struct inode *old_inode, * * Returns 0 if access is permitted, -EACCES otherwise */ -static int smack_inode_permission(struct inode *inode, int mask) +static int smack_inode_permission(struct inode *inode, int mask, unsigned flags) { struct smk_audit_info ad; @@ -696,6 +696,10 @@ static int smack_inode_permission(struct inode *inode, int mask) */ if (mask == 0) return 0; + + /* May be droppable after audit */ + if (flags & IPERM_FLAG_RCU) + return -ECHILD; smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_FS); smk_ad_setfield_u_fs_inode(&ad, inode); return smk_curacc(smk_of_inode(inode), mask, &ad); -- cgit v1.1 From 9ade0cf440a1e5800dc68eef2e77b8d9d83a6dff Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Mon, 25 Apr 2011 16:26:29 -0400 Subject: SELINUX: Make selinux cache VFS RCU walks safe Now that the security modules can decide whether they support the dcache RCU walk or not it's possible to make selinux a bit more RCU friendly. The SELinux AVC and security server access decision code is RCU safe. A specific piece of the LSM audit code may not be RCU safe. This patch makes the VFS RCU walk retry if it would hit the non RCU safe chunk of code. It will normally just work under RCU. This is done simply by passing the VFS RCU state as a flag down into the avc_audit() code and returning ECHILD there if it would have an issue. Based-on-patch-by: Andi Kleen Signed-off-by: Eric Paris Signed-off-by: Linus Torvalds --- security/selinux/avc.c | 36 +++++++++++++++++++++++++++++------- security/selinux/hooks.c | 26 +++++++++++++------------- security/selinux/include/avc.h | 18 +++++++++++++----- 3 files changed, 55 insertions(+), 25 deletions(-) (limited to 'security') diff --git a/security/selinux/avc.c b/security/selinux/avc.c index 9da6420..1d027e2 100644 --- a/security/selinux/avc.c +++ b/security/selinux/avc.c @@ -471,6 +471,7 @@ static void avc_audit_post_callback(struct audit_buffer *ab, void *a) * @avd: access vector decisions * @result: result from avc_has_perm_noaudit * @a: auxiliary audit data + * @flags: VFS walk flags * * Audit the granting or denial of permissions in accordance * with the policy. This function is typically called by @@ -481,9 +482,10 @@ static void avc_audit_post_callback(struct audit_buffer *ab, void *a) * be performed under a lock, to allow the lock to be released * before calling the auditing code. */ -void avc_audit(u32 ssid, u32 tsid, +int avc_audit(u32 ssid, u32 tsid, u16 tclass, u32 requested, - struct av_decision *avd, int result, struct common_audit_data *a) + struct av_decision *avd, int result, struct common_audit_data *a, + unsigned flags) { struct common_audit_data stack_data; u32 denied, audited; @@ -515,11 +517,24 @@ void avc_audit(u32 ssid, u32 tsid, else audited = requested & avd->auditallow; if (!audited) - return; + return 0; + if (!a) { a = &stack_data; COMMON_AUDIT_DATA_INIT(a, NONE); } + + /* + * When in a RCU walk do the audit on the RCU retry. This is because + * the collection of the dname in an inode audit message is not RCU + * safe. Note this may drop some audits when the situation changes + * during retry. However this is logically just as if the operation + * happened a little later. + */ + if ((a->type == LSM_AUDIT_DATA_FS) && + (flags & IPERM_FLAG_RCU)) + return -ECHILD; + a->selinux_audit_data.tclass = tclass; a->selinux_audit_data.requested = requested; a->selinux_audit_data.ssid = ssid; @@ -529,6 +544,7 @@ void avc_audit(u32 ssid, u32 tsid, a->lsm_pre_audit = avc_audit_pre_callback; a->lsm_post_audit = avc_audit_post_callback; common_lsm_audit(a); + return 0; } /** @@ -793,6 +809,7 @@ int avc_has_perm_noaudit(u32 ssid, u32 tsid, * @tclass: target security class * @requested: requested permissions, interpreted based on @tclass * @auditdata: auxiliary audit data + * @flags: VFS walk flags * * Check the AVC to determine whether the @requested permissions are granted * for the SID pair (@ssid, @tsid), interpreting the permissions @@ -802,14 +819,19 @@ int avc_has_perm_noaudit(u32 ssid, u32 tsid, * permissions are granted, -%EACCES if any permissions are denied, or * another -errno upon other errors. */ -int avc_has_perm(u32 ssid, u32 tsid, u16 tclass, - u32 requested, struct common_audit_data *auditdata) +int avc_has_perm_flags(u32 ssid, u32 tsid, u16 tclass, + u32 requested, struct common_audit_data *auditdata, + unsigned flags) { struct av_decision avd; - int rc; + int rc, rc2; rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd); - avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata); + + rc2 = avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata, + flags); + if (rc2) + return rc2; return rc; } diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index a73f4e4..f7cf0ea 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -1446,8 +1446,11 @@ static int task_has_capability(struct task_struct *tsk, } rc = avc_has_perm_noaudit(sid, sid, sclass, av, 0, &avd); - if (audit == SECURITY_CAP_AUDIT) - avc_audit(sid, sid, sclass, av, &avd, rc, &ad); + if (audit == SECURITY_CAP_AUDIT) { + int rc2 = avc_audit(sid, sid, sclass, av, &avd, rc, &ad, 0); + if (rc2) + return rc2; + } return rc; } @@ -1467,7 +1470,8 @@ static int task_has_system(struct task_struct *tsk, static int inode_has_perm(const struct cred *cred, struct inode *inode, u32 perms, - struct common_audit_data *adp) + struct common_audit_data *adp, + unsigned flags) { struct inode_security_struct *isec; struct common_audit_data ad; @@ -1487,7 +1491,7 @@ static int inode_has_perm(const struct cred *cred, ad.u.fs.inode = inode; } - return avc_has_perm(sid, isec->sid, isec->sclass, perms, adp); + return avc_has_perm_flags(sid, isec->sid, isec->sclass, perms, adp, flags); } /* Same as inode_has_perm, but pass explicit audit data containing @@ -1504,7 +1508,7 @@ static inline int dentry_has_perm(const struct cred *cred, COMMON_AUDIT_DATA_INIT(&ad, FS); ad.u.fs.path.mnt = mnt; ad.u.fs.path.dentry = dentry; - return inode_has_perm(cred, inode, av, &ad); + return inode_has_perm(cred, inode, av, &ad, 0); } /* Check whether a task can use an open file descriptor to @@ -1540,7 +1544,7 @@ static int file_has_perm(const struct cred *cred, /* av is zero if only checking access to the descriptor. */ rc = 0; if (av) - rc = inode_has_perm(cred, inode, av, &ad); + rc = inode_has_perm(cred, inode, av, &ad, 0); out: return rc; @@ -2103,7 +2107,7 @@ static inline void flush_unauthorized_files(const struct cred *cred, file = file_priv->file; inode = file->f_path.dentry->d_inode; if (inode_has_perm(cred, inode, - FILE__READ | FILE__WRITE, NULL)) { + FILE__READ | FILE__WRITE, NULL, 0)) { drop_tty = 1; } } @@ -2649,10 +2653,6 @@ static int selinux_inode_permission(struct inode *inode, int mask, unsigned flag if (!mask) return 0; - /* May be droppable after audit */ - if (flags & IPERM_FLAG_RCU) - return -ECHILD; - COMMON_AUDIT_DATA_INIT(&ad, FS); ad.u.fs.inode = inode; @@ -2661,7 +2661,7 @@ static int selinux_inode_permission(struct inode *inode, int mask, unsigned flag perms = file_mask_to_av(inode->i_mode, mask); - return inode_has_perm(cred, inode, perms, &ad); + return inode_has_perm(cred, inode, perms, &ad, flags); } static int selinux_inode_setattr(struct dentry *dentry, struct iattr *iattr) @@ -3209,7 +3209,7 @@ static int selinux_dentry_open(struct file *file, const struct cred *cred) * new inode label or new policy. * This check is not redundant - do not remove. */ - return inode_has_perm(cred, inode, open_file_to_av(file), NULL); + return inode_has_perm(cred, inode, open_file_to_av(file), NULL, 0); } /* task security operations */ diff --git a/security/selinux/include/avc.h b/security/selinux/include/avc.h index 5615081..e77b2ac 100644 --- a/security/selinux/include/avc.h +++ b/security/selinux/include/avc.h @@ -54,11 +54,11 @@ struct avc_cache_stats { void __init avc_init(void); -void avc_audit(u32 ssid, u32 tsid, +int avc_audit(u32 ssid, u32 tsid, u16 tclass, u32 requested, struct av_decision *avd, int result, - struct common_audit_data *a); + struct common_audit_data *a, unsigned flags); #define AVC_STRICT 1 /* Ignore permissive mode. */ int avc_has_perm_noaudit(u32 ssid, u32 tsid, @@ -66,9 +66,17 @@ int avc_has_perm_noaudit(u32 ssid, u32 tsid, unsigned flags, struct av_decision *avd); -int avc_has_perm(u32 ssid, u32 tsid, - u16 tclass, u32 requested, - struct common_audit_data *auditdata); +int avc_has_perm_flags(u32 ssid, u32 tsid, + u16 tclass, u32 requested, + struct common_audit_data *auditdata, + unsigned); + +static inline int avc_has_perm(u32 ssid, u32 tsid, + u16 tclass, u32 requested, + struct common_audit_data *auditdata) +{ + return avc_has_perm_flags(ssid, tsid, tclass, requested, auditdata, 0); +} u32 avc_policy_seqno(void); -- cgit v1.1