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 2984ea4f776..bbb51156261 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 101142369db..4ba6d4cc061 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 f9c3764e485..a73f4e46377 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 c6f8fcadae0..400a5d5cde6 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 v1.2.3 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 9da6420e205..1d027e29ce8 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 a73f4e46377..f7cf0ea6fae 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 5615081b73e..e77b2ac2908 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 v1.2.3 From cb1e922fa104bb0bb3aa5fc6ca7f7e070f3b55e9 Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Thu, 28 Apr 2011 15:11:21 -0400 Subject: SELinux: pass last path component in may_create New inodes are created in a two stage process. We first will compute the label on a new inode in security_inode_create() and check if the operation is allowed. We will then actually re-compute that same label and apply it in security_inode_init_security(). The change to do new label calculations based in part on the last component of the path name only passed the path component information all the way down the security_inode_init_security hook. Down the security_inode_create hook the path information did not make it past may_create. Thus the two calculations came up differently and the permissions check might not actually be against the label that is created. Pass and use the same information in both places to harmonize the calculations and checks. Reported-by: Dominick Grift Signed-off-by: Eric Paris --- security/selinux/hooks.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'security') diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index d52a9250741..9a93af81a0c 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -1573,7 +1573,8 @@ static int may_create(struct inode *dir, return rc; if (!newsid || !(sbsec->flags & SE_SBLABELSUPP)) { - rc = security_transition_sid(sid, dsec->sid, tclass, NULL, &newsid); + rc = security_transition_sid(sid, dsec->sid, tclass, + &dentry->d_name, &newsid); if (rc) return rc; } -- cgit v1.2.3 From 5d30b10bd68df007e7ae21e77d1e0ce184b53040 Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Thu, 28 Apr 2011 15:55:52 -0400 Subject: flex_array: flex_array_prealloc takes a number of elements, not an end Change flex_array_prealloc to take the number of elements for which space should be allocated instead of the last (inclusive) element. Users and documentation are updated accordingly. flex_arrays got introduced before they had users. When folks started using it, they ended up needing a different API than was coded up originally. This swaps over to the API that folks apparently need. Based-on-patch-by: Steffen Klassert Signed-off-by: Eric Paris Tested-by: Chris Richards Acked-by: Dave Hansen Cc: stable@kernel.org [2.6.38+] --- Documentation/flexible-arrays.txt | 4 ++-- include/linux/flex_array.h | 2 +- lib/flex_array.c | 13 ++++++++----- security/selinux/ss/policydb.c | 6 +++--- 4 files changed, 14 insertions(+), 11 deletions(-) (limited to 'security') diff --git a/Documentation/flexible-arrays.txt b/Documentation/flexible-arrays.txt index cb8a3a00cc9..df904aec990 100644 --- a/Documentation/flexible-arrays.txt +++ b/Documentation/flexible-arrays.txt @@ -66,10 +66,10 @@ trick is to ensure that any needed memory allocations are done before entering atomic context, using: int flex_array_prealloc(struct flex_array *array, unsigned int start, - unsigned int end, gfp_t flags); + unsigned int nr_elements, gfp_t flags); This function will ensure that memory for the elements indexed in the range -defined by start and end has been allocated. Thereafter, a +defined by start and nr_elements has been allocated. Thereafter, a flex_array_put() call on an element in that range is guaranteed not to block. diff --git a/include/linux/flex_array.h b/include/linux/flex_array.h index 70e4efabe0f..ebeb2f3ad06 100644 --- a/include/linux/flex_array.h +++ b/include/linux/flex_array.h @@ -61,7 +61,7 @@ struct flex_array { struct flex_array *flex_array_alloc(int element_size, unsigned int total, gfp_t flags); int flex_array_prealloc(struct flex_array *fa, unsigned int start, - unsigned int end, gfp_t flags); + unsigned int nr_elements, gfp_t flags); void flex_array_free(struct flex_array *fa); void flex_array_free_parts(struct flex_array *fa); int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src, diff --git a/lib/flex_array.c b/lib/flex_array.c index c0ea40ba208..0c33b24498b 100644 --- a/lib/flex_array.c +++ b/lib/flex_array.c @@ -232,10 +232,10 @@ EXPORT_SYMBOL(flex_array_clear); /** * flex_array_prealloc - guarantee that array space exists - * @fa: the flex array for which to preallocate parts - * @start: index of first array element for which space is allocated - * @end: index of last (inclusive) element for which space is allocated - * @flags: page allocation flags + * @fa: the flex array for which to preallocate parts + * @start: index of first array element for which space is allocated + * @nr_elements: number of elements for which space is allocated + * @flags: page allocation flags * * This will guarantee that no future calls to flex_array_put() * will allocate memory. It can be used if you are expecting to @@ -245,13 +245,16 @@ EXPORT_SYMBOL(flex_array_clear); * Locking must be provided by the caller. */ int flex_array_prealloc(struct flex_array *fa, unsigned int start, - unsigned int end, gfp_t flags) + unsigned int nr_elements, gfp_t flags) { int start_part; int end_part; int part_nr; + unsigned int end; struct flex_array_part *part; + end = start + nr_elements - 1; + if (start >= fa->total_nr_elements || end >= fa->total_nr_elements) return -ENOSPC; if (elements_fit_in_base(fa)) diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c index e7b850ad57e..e6e7ce0d3d5 100644 --- a/security/selinux/ss/policydb.c +++ b/security/selinux/ss/policydb.c @@ -502,7 +502,7 @@ static int policydb_index(struct policydb *p) goto out; rc = flex_array_prealloc(p->type_val_to_struct_array, 0, - p->p_types.nprim - 1, GFP_KERNEL | __GFP_ZERO); + p->p_types.nprim, GFP_KERNEL | __GFP_ZERO); if (rc) goto out; @@ -519,7 +519,7 @@ static int policydb_index(struct policydb *p) goto out; rc = flex_array_prealloc(p->sym_val_to_name[i], - 0, p->symtab[i].nprim - 1, + 0, p->symtab[i].nprim, GFP_KERNEL | __GFP_ZERO); if (rc) goto out; @@ -2375,7 +2375,7 @@ int policydb_read(struct policydb *p, void *fp) goto bad; /* preallocate so we don't have to worry about the put ever failing */ - rc = flex_array_prealloc(p->type_attr_map_array, 0, p->p_types.nprim - 1, + rc = flex_array_prealloc(p->type_attr_map_array, 0, p->p_types.nprim, GFP_KERNEL | __GFP_ZERO); if (rc) goto bad; -- cgit v1.2.3 From 93826c092c385549c04af184fbebd43f36995c69 Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Thu, 7 Apr 2011 14:46:59 -0400 Subject: SELinux: delete debugging printks from filename_trans rule processing The filename_trans rule processing has some printk(KERN_ERR ) messages which were intended as debug aids in creating the code but weren't removed before it was submitted. Remove them. Reported-by: Paul Bolle Signed-off-by: Eric Paris --- security/selinux/ss/policydb.c | 4 ---- 1 file changed, 4 deletions(-) (limited to 'security') diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c index e6e7ce0d3d5..7102457661d 100644 --- a/security/selinux/ss/policydb.c +++ b/security/selinux/ss/policydb.c @@ -1819,8 +1819,6 @@ static int filename_trans_read(struct policydb *p, void *fp) goto out; nel = le32_to_cpu(buf[0]); - printk(KERN_ERR "%s: nel=%d\n", __func__, nel); - last = p->filename_trans; while (last && last->next) last = last->next; @@ -1857,8 +1855,6 @@ static int filename_trans_read(struct policydb *p, void *fp) goto out; name[len] = 0; - printk(KERN_ERR "%s: ft=%p ft->name=%p ft->name=%s\n", __func__, ft, ft->name, ft->name); - rc = next_entry(buf, fp, sizeof(u32) * 4); if (rc) goto out; -- cgit v1.2.3