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authorLachlan McIlroy <lachlan@redback.melbourne.sgi.com>2008-12-29 16:47:18 +1100
committerLachlan McIlroy <lachlan@redback.melbourne.sgi.com>2008-12-29 16:47:18 +1100
commit0a8c5395f90f06d128247844b2515c8bf3f2826b (patch)
treed95382dcdfa303b99d480c01763d6cb6767fdaca /security/commoncap.c
parent[XFS] Fix race in xfs_write() between direct and buffered I/O with DMAPI (diff)
parentMerge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc (diff)
downloadlinux-dev-0a8c5395f90f06d128247844b2515c8bf3f2826b.tar.xz
linux-dev-0a8c5395f90f06d128247844b2515c8bf3f2826b.zip
[XFS] Fix merge failures
Merge git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6 Conflicts: fs/xfs/linux-2.6/xfs_cred.h fs/xfs/linux-2.6/xfs_globals.h fs/xfs/linux-2.6/xfs_ioctl.c fs/xfs/xfs_vnodeops.h Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Diffstat (limited to 'security/commoncap.c')
-rw-r--r--security/commoncap.c830
1 files changed, 537 insertions, 293 deletions
diff --git a/security/commoncap.c b/security/commoncap.c
index 3976613db829..79713545cd63 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -8,6 +8,7 @@
*/
#include <linux/capability.h>
+#include <linux/audit.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
@@ -29,7 +30,7 @@
int cap_netlink_send(struct sock *sk, struct sk_buff *skb)
{
- NETLINK_CB(skb).eff_cap = current->cap_effective;
+ NETLINK_CB(skb).eff_cap = current_cap();
return 0;
}
@@ -39,23 +40,41 @@ int cap_netlink_recv(struct sk_buff *skb, int cap)
return -EPERM;
return 0;
}
-
EXPORT_SYMBOL(cap_netlink_recv);
-/*
+/**
+ * cap_capable - Determine whether a task has a particular effective capability
+ * @tsk: The task to query
+ * @cap: The capability to check for
+ * @audit: Whether to write an audit message or not
+ *
+ * Determine whether the nominated task has the specified capability amongst
+ * its effective set, returning 0 if it does, -ve if it does not.
+ *
* NOTE WELL: cap_capable() cannot be used like the kernel's capable()
- * function. That is, it has the reverse semantics: cap_capable()
- * returns 0 when a task has a capability, but the kernel's capable()
- * returns 1 for this case.
+ * function. That is, it has the reverse semantics: cap_capable() returns 0
+ * when a task has a capability, but the kernel's capable() returns 1 for this
+ * case.
*/
-int cap_capable (struct task_struct *tsk, int cap)
+int cap_capable(struct task_struct *tsk, int cap, int audit)
{
+ __u32 cap_raised;
+
/* Derived from include/linux/sched.h:capable. */
- if (cap_raised(tsk->cap_effective, cap))
- return 0;
- return -EPERM;
+ rcu_read_lock();
+ cap_raised = cap_raised(__task_cred(tsk)->cap_effective, cap);
+ rcu_read_unlock();
+ return cap_raised ? 0 : -EPERM;
}
+/**
+ * cap_settime - Determine whether the current process may set the system clock
+ * @ts: The time to set
+ * @tz: The timezone to set
+ *
+ * Determine whether the current process may set the system clock and timezone
+ * information, returning 0 if permission granted, -ve if denied.
+ */
int cap_settime(struct timespec *ts, struct timezone *tz)
{
if (!capable(CAP_SYS_TIME))
@@ -63,121 +82,157 @@ int cap_settime(struct timespec *ts, struct timezone *tz)
return 0;
}
+/**
+ * cap_ptrace_may_access - Determine whether the current process may access
+ * another
+ * @child: The process to be accessed
+ * @mode: The mode of attachment.
+ *
+ * Determine whether a process may access another, returning 0 if permission
+ * granted, -ve if denied.
+ */
int cap_ptrace_may_access(struct task_struct *child, unsigned int mode)
{
- /* Derived from arch/i386/kernel/ptrace.c:sys_ptrace. */
- if (cap_issubset(child->cap_permitted, current->cap_permitted))
- return 0;
- if (capable(CAP_SYS_PTRACE))
- return 0;
- return -EPERM;
+ int ret = 0;
+
+ rcu_read_lock();
+ if (!cap_issubset(__task_cred(child)->cap_permitted,
+ current_cred()->cap_permitted) &&
+ !capable(CAP_SYS_PTRACE))
+ ret = -EPERM;
+ rcu_read_unlock();
+ return ret;
}
+/**
+ * cap_ptrace_traceme - Determine whether another process may trace the current
+ * @parent: The task proposed to be the tracer
+ *
+ * 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)
{
- /* Derived from arch/i386/kernel/ptrace.c:sys_ptrace. */
- if (cap_issubset(current->cap_permitted, parent->cap_permitted))
- return 0;
- if (has_capability(parent, CAP_SYS_PTRACE))
- return 0;
- return -EPERM;
+ int ret = 0;
+
+ rcu_read_lock();
+ if (!cap_issubset(current_cred()->cap_permitted,
+ __task_cred(parent)->cap_permitted) &&
+ !has_capability(parent, CAP_SYS_PTRACE))
+ ret = -EPERM;
+ rcu_read_unlock();
+ return ret;
}
-int cap_capget (struct task_struct *target, kernel_cap_t *effective,
- kernel_cap_t *inheritable, kernel_cap_t *permitted)
+/**
+ * cap_capget - Retrieve a task's capability sets
+ * @target: The task from which to retrieve the capability sets
+ * @effective: The place to record the effective set
+ * @inheritable: The place to record the inheritable set
+ * @permitted: The place to record the permitted set
+ *
+ * This function retrieves the capabilities of the nominated task and returns
+ * them to the caller.
+ */
+int cap_capget(struct task_struct *target, kernel_cap_t *effective,
+ kernel_cap_t *inheritable, kernel_cap_t *permitted)
{
+ const struct cred *cred;
+
/* Derived from kernel/capability.c:sys_capget. */
- *effective = target->cap_effective;
- *inheritable = target->cap_inheritable;
- *permitted = target->cap_permitted;
+ rcu_read_lock();
+ cred = __task_cred(target);
+ *effective = cred->cap_effective;
+ *inheritable = cred->cap_inheritable;
+ *permitted = cred->cap_permitted;
+ rcu_read_unlock();
return 0;
}
-#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
-
-static inline int cap_block_setpcap(struct task_struct *target)
-{
- /*
- * No support for remote process capability manipulation with
- * filesystem capability support.
- */
- return (target != current);
-}
-
+/*
+ * Determine whether the inheritable capabilities are limited to the old
+ * permitted set. Returns 1 if they are limited, 0 if they are not.
+ */
static inline int cap_inh_is_capped(void)
{
- /*
- * Return 1 if changes to the inheritable set are limited
- * to the old permitted set. That is, if the current task
- * does *not* possess the CAP_SETPCAP capability.
- */
- return (cap_capable(current, CAP_SETPCAP) != 0);
-}
-
-static inline int cap_limit_ptraced_target(void) { return 1; }
-
-#else /* ie., ndef CONFIG_SECURITY_FILE_CAPABILITIES */
+#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
-static inline int cap_block_setpcap(struct task_struct *t) { return 0; }
-static inline int cap_inh_is_capped(void) { return 1; }
-static inline int cap_limit_ptraced_target(void)
-{
- return !capable(CAP_SETPCAP);
+ /* they are so limited unless the current task has the CAP_SETPCAP
+ * capability
+ */
+ if (cap_capable(current, CAP_SETPCAP, SECURITY_CAP_AUDIT) == 0)
+ return 0;
+#endif
+ return 1;
}
-#endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */
-
-int cap_capset_check (struct task_struct *target, kernel_cap_t *effective,
- kernel_cap_t *inheritable, kernel_cap_t *permitted)
-{
- if (cap_block_setpcap(target)) {
- return -EPERM;
- }
- if (cap_inh_is_capped()
- && !cap_issubset(*inheritable,
- cap_combine(target->cap_inheritable,
- current->cap_permitted))) {
+/**
+ * cap_capset - Validate and apply proposed changes to current's capabilities
+ * @new: The proposed new credentials; alterations should be made here
+ * @old: The current task's current credentials
+ * @effective: A pointer to the proposed new effective capabilities set
+ * @inheritable: A pointer to the proposed new inheritable capabilities set
+ * @permitted: A pointer to the proposed new permitted capabilities set
+ *
+ * This function validates and applies a proposed mass change to the current
+ * process's capability sets. The changes are made to the proposed new
+ * credentials, and assuming no error, will be committed by the caller of LSM.
+ */
+int cap_capset(struct cred *new,
+ const struct cred *old,
+ const kernel_cap_t *effective,
+ const kernel_cap_t *inheritable,
+ const kernel_cap_t *permitted)
+{
+ if (cap_inh_is_capped() &&
+ !cap_issubset(*inheritable,
+ cap_combine(old->cap_inheritable,
+ old->cap_permitted)))
/* incapable of using this inheritable set */
return -EPERM;
- }
+
if (!cap_issubset(*inheritable,
- cap_combine(target->cap_inheritable,
- current->cap_bset))) {
+ cap_combine(old->cap_inheritable,
+ old->cap_bset)))
/* no new pI capabilities outside bounding set */
return -EPERM;
- }
/* verify restrictions on target's new Permitted set */
- if (!cap_issubset (*permitted,
- cap_combine (target->cap_permitted,
- current->cap_permitted))) {
+ if (!cap_issubset(*permitted, old->cap_permitted))
return -EPERM;
- }
/* verify the _new_Effective_ is a subset of the _new_Permitted_ */
- if (!cap_issubset (*effective, *permitted)) {
+ if (!cap_issubset(*effective, *permitted))
return -EPERM;
- }
+ new->cap_effective = *effective;
+ new->cap_inheritable = *inheritable;
+ new->cap_permitted = *permitted;
return 0;
}
-void cap_capset_set (struct task_struct *target, kernel_cap_t *effective,
- kernel_cap_t *inheritable, kernel_cap_t *permitted)
-{
- target->cap_effective = *effective;
- target->cap_inheritable = *inheritable;
- target->cap_permitted = *permitted;
-}
-
+/*
+ * Clear proposed capability sets for execve().
+ */
static inline void bprm_clear_caps(struct linux_binprm *bprm)
{
- cap_clear(bprm->cap_post_exec_permitted);
+ cap_clear(bprm->cred->cap_permitted);
bprm->cap_effective = false;
}
#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
+/**
+ * cap_inode_need_killpriv - Determine if inode change affects privileges
+ * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV
+ *
+ * Determine if an inode having a change applied that's marked ATTR_KILL_PRIV
+ * affects the security markings on that inode, and if it is, should
+ * inode_killpriv() be invoked or the change rejected?
+ *
+ * Returns 0 if granted; +ve if granted, but inode_killpriv() is required; and
+ * -ve to deny the change.
+ */
int cap_inode_need_killpriv(struct dentry *dentry)
{
struct inode *inode = dentry->d_inode;
@@ -192,6 +247,14 @@ int cap_inode_need_killpriv(struct dentry *dentry)
return 1;
}
+/**
+ * cap_inode_killpriv - Erase the security markings on an inode
+ * @dentry: The inode/dentry to alter
+ *
+ * Erase the privilege-enhancing security markings on an inode.
+ *
+ * Returns 0 if successful, -ve on error.
+ */
int cap_inode_killpriv(struct dentry *dentry)
{
struct inode *inode = dentry->d_inode;
@@ -202,19 +265,75 @@ int cap_inode_killpriv(struct dentry *dentry)
return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS);
}
-static inline int cap_from_disk(struct vfs_cap_data *caps,
- struct linux_binprm *bprm, unsigned size)
+/*
+ * Calculate the new process capability sets from the capability sets attached
+ * to a file.
+ */
+static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps,
+ struct linux_binprm *bprm,
+ bool *effective)
+{
+ struct cred *new = bprm->cred;
+ unsigned i;
+ int ret = 0;
+
+ if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE)
+ *effective = true;
+
+ CAP_FOR_EACH_U32(i) {
+ __u32 permitted = caps->permitted.cap[i];
+ __u32 inheritable = caps->inheritable.cap[i];
+
+ /*
+ * pP' = (X & fP) | (pI & fI)
+ */
+ new->cap_permitted.cap[i] =
+ (new->cap_bset.cap[i] & permitted) |
+ (new->cap_inheritable.cap[i] & inheritable);
+
+ if (permitted & ~new->cap_permitted.cap[i])
+ /* insufficient to execute correctly */
+ ret = -EPERM;
+ }
+
+ /*
+ * For legacy apps, with no internal support for recognizing they
+ * do not have enough capabilities, we return an error if they are
+ * missing some "forced" (aka file-permitted) capabilities.
+ */
+ return *effective ? ret : 0;
+}
+
+/*
+ * Extract the on-exec-apply capability sets for an executable file.
+ */
+int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps)
{
+ struct inode *inode = dentry->d_inode;
__u32 magic_etc;
unsigned tocopy, i;
- int ret;
+ int size;
+ struct vfs_cap_data caps;
+
+ memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data));
+
+ if (!inode || !inode->i_op || !inode->i_op->getxattr)
+ return -ENODATA;
+
+ size = inode->i_op->getxattr((struct dentry *)dentry, XATTR_NAME_CAPS, &caps,
+ XATTR_CAPS_SZ);
+ if (size == -ENODATA || size == -EOPNOTSUPP)
+ /* no data, that's ok */
+ return -ENODATA;
+ if (size < 0)
+ return size;
if (size < sizeof(magic_etc))
return -EINVAL;
- magic_etc = le32_to_cpu(caps->magic_etc);
+ cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps.magic_etc);
- switch ((magic_etc & VFS_CAP_REVISION_MASK)) {
+ switch (magic_etc & VFS_CAP_REVISION_MASK) {
case VFS_CAP_REVISION_1:
if (size != XATTR_CAPS_SZ_1)
return -EINVAL;
@@ -229,77 +348,48 @@ static inline int cap_from_disk(struct vfs_cap_data *caps,
return -EINVAL;
}
- if (magic_etc & VFS_CAP_FLAGS_EFFECTIVE) {
- bprm->cap_effective = true;
- } else {
- bprm->cap_effective = false;
- }
-
- ret = 0;
-
CAP_FOR_EACH_U32(i) {
- __u32 value_cpu;
-
- if (i >= tocopy) {
- /*
- * Legacy capability sets have no upper bits
- */
- bprm->cap_post_exec_permitted.cap[i] = 0;
- continue;
- }
- /*
- * pP' = (X & fP) | (pI & fI)
- */
- value_cpu = le32_to_cpu(caps->data[i].permitted);
- bprm->cap_post_exec_permitted.cap[i] =
- (current->cap_bset.cap[i] & value_cpu) |
- (current->cap_inheritable.cap[i] &
- le32_to_cpu(caps->data[i].inheritable));
- if (value_cpu & ~bprm->cap_post_exec_permitted.cap[i]) {
- /*
- * insufficient to execute correctly
- */
- ret = -EPERM;
- }
+ if (i >= tocopy)
+ break;
+ cpu_caps->permitted.cap[i] = le32_to_cpu(caps.data[i].permitted);
+ cpu_caps->inheritable.cap[i] = le32_to_cpu(caps.data[i].inheritable);
}
- /*
- * For legacy apps, with no internal support for recognizing they
- * do not have enough capabilities, we return an error if they are
- * missing some "forced" (aka file-permitted) capabilities.
- */
- return bprm->cap_effective ? ret : 0;
+ return 0;
}
-/* Locate any VFS capabilities: */
-static int get_file_caps(struct linux_binprm *bprm)
+/*
+ * Attempt to get the on-exec apply capability sets for an executable file from
+ * its xattrs and, if present, apply them to the proposed credentials being
+ * constructed by execve().
+ */
+static int get_file_caps(struct linux_binprm *bprm, bool *effective)
{
struct dentry *dentry;
int rc = 0;
- struct vfs_cap_data vcaps;
- struct inode *inode;
+ struct cpu_vfs_cap_data vcaps;
bprm_clear_caps(bprm);
+ if (!file_caps_enabled)
+ return 0;
+
if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)
return 0;
dentry = dget(bprm->file->f_dentry);
- inode = dentry->d_inode;
- if (!inode->i_op || !inode->i_op->getxattr)
- goto out;
- rc = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, &vcaps,
- XATTR_CAPS_SZ);
- if (rc == -ENODATA || rc == -EOPNOTSUPP) {
- /* no data, that's ok */
- rc = 0;
+ rc = get_vfs_caps_from_disk(dentry, &vcaps);
+ if (rc < 0) {
+ if (rc == -EINVAL)
+ printk(KERN_NOTICE "%s: get_vfs_caps_from_disk returned %d for %s\n",
+ __func__, rc, bprm->filename);
+ else if (rc == -ENODATA)
+ rc = 0;
goto out;
}
- if (rc < 0)
- goto out;
- rc = cap_from_disk(&vcaps, bprm, rc);
+ rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective);
if (rc == -EINVAL)
printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n",
__func__, rc, bprm->filename);
@@ -323,18 +413,57 @@ int cap_inode_killpriv(struct dentry *dentry)
return 0;
}
-static inline int get_file_caps(struct linux_binprm *bprm)
+int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps)
+{
+ memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data));
+ return -ENODATA;
+}
+
+static inline int get_file_caps(struct linux_binprm *bprm, bool *effective)
{
bprm_clear_caps(bprm);
return 0;
}
#endif
-int cap_bprm_set_security (struct linux_binprm *bprm)
+/*
+ * Determine whether a exec'ing process's new permitted capabilities should be
+ * limited to just what it already has.
+ *
+ * This prevents processes that are being ptraced from gaining access to
+ * CAP_SETPCAP, unless the process they're tracing already has it, and the
+ * binary they're executing has filecaps that elevate it.
+ *
+ * Returns 1 if they should be limited, 0 if they are not.
+ */
+static inline int cap_limit_ptraced_target(void)
+{
+#ifndef CONFIG_SECURITY_FILE_CAPABILITIES
+ if (capable(CAP_SETPCAP))
+ return 0;
+#endif
+ return 1;
+}
+
+/**
+ * cap_bprm_set_creds - Set up the proposed credentials for execve().
+ * @bprm: The execution parameters, including the proposed creds
+ *
+ * Set up the proposed credentials for a new execution context being
+ * constructed by execve(). The proposed creds in @bprm->cred is altered,
+ * which won't take effect immediately. Returns 0 if successful, -ve on error.
+ */
+int cap_bprm_set_creds(struct linux_binprm *bprm)
{
+ const struct cred *old = current_cred();
+ struct cred *new = bprm->cred;
+ bool effective;
int ret;
- ret = get_file_caps(bprm);
+ effective = false;
+ ret = get_file_caps(bprm, &effective);
+ if (ret < 0)
+ return ret;
if (!issecure(SECURE_NOROOT)) {
/*
@@ -342,75 +471,113 @@ int cap_bprm_set_security (struct linux_binprm *bprm)
* executables under compatibility mode, we override the
* capability sets for the file.
*
- * If only the real uid is 0, we do not set the effective
- * bit.
+ * If only the real uid is 0, we do not set the effective bit.
*/
- if (bprm->e_uid == 0 || current->uid == 0) {
+ if (new->euid == 0 || new->uid == 0) {
/* pP' = (cap_bset & ~0) | (pI & ~0) */
- bprm->cap_post_exec_permitted = cap_combine(
- current->cap_bset, current->cap_inheritable
- );
- bprm->cap_effective = (bprm->e_uid == 0);
- ret = 0;
+ new->cap_permitted = cap_combine(old->cap_bset,
+ old->cap_inheritable);
}
+ if (new->euid == 0)
+ effective = true;
}
- return ret;
-}
-
-void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe)
-{
- if (bprm->e_uid != current->uid || bprm->e_gid != current->gid ||
- !cap_issubset(bprm->cap_post_exec_permitted,
- current->cap_permitted)) {
- set_dumpable(current->mm, suid_dumpable);
- current->pdeath_signal = 0;
-
- if (unsafe & ~LSM_UNSAFE_PTRACE_CAP) {
- if (!capable(CAP_SETUID)) {
- bprm->e_uid = current->uid;
- bprm->e_gid = current->gid;
- }
- if (cap_limit_ptraced_target()) {
- bprm->cap_post_exec_permitted = cap_intersect(
- bprm->cap_post_exec_permitted,
- current->cap_permitted);
- }
+ /* Don't let someone trace a set[ug]id/setpcap binary with the revised
+ * credentials unless they have the appropriate permit
+ */
+ if ((new->euid != old->uid ||
+ new->egid != old->gid ||
+ !cap_issubset(new->cap_permitted, old->cap_permitted)) &&
+ bprm->unsafe & ~LSM_UNSAFE_PTRACE_CAP) {
+ /* downgrade; they get no more than they had, and maybe less */
+ if (!capable(CAP_SETUID)) {
+ new->euid = new->uid;
+ new->egid = new->gid;
}
+ if (cap_limit_ptraced_target())
+ new->cap_permitted = cap_intersect(new->cap_permitted,
+ old->cap_permitted);
}
- current->suid = current->euid = current->fsuid = bprm->e_uid;
- current->sgid = current->egid = current->fsgid = bprm->e_gid;
+ new->suid = new->fsuid = new->euid;
+ new->sgid = new->fsgid = new->egid;
- /* For init, we want to retain the capabilities set
- * in the init_task struct. Thus we skip the usual
- * capability rules */
+ /* For init, we want to retain the capabilities set in the initial
+ * task. Thus we skip the usual capability rules
+ */
if (!is_global_init(current)) {
- current->cap_permitted = bprm->cap_post_exec_permitted;
- if (bprm->cap_effective)
- current->cap_effective = bprm->cap_post_exec_permitted;
+ if (effective)
+ new->cap_effective = new->cap_permitted;
else
- cap_clear(current->cap_effective);
+ cap_clear(new->cap_effective);
}
+ bprm->cap_effective = effective;
- /* AUD: Audit candidate if current->cap_effective is set */
+ /*
+ * Audit candidate if current->cap_effective is set
+ *
+ * We do not bother to audit if 3 things are true:
+ * 1) cap_effective has all caps
+ * 2) we are root
+ * 3) root is supposed to have all caps (SECURE_NOROOT)
+ * Since this is just a normal root execing a process.
+ *
+ * Number 1 above might fail if you don't have a full bset, but I think
+ * that is interesting information to audit.
+ */
+ if (!cap_isclear(new->cap_effective)) {
+ if (!cap_issubset(CAP_FULL_SET, new->cap_effective) ||
+ new->euid != 0 || new->uid != 0 ||
+ issecure(SECURE_NOROOT)) {
+ ret = audit_log_bprm_fcaps(bprm, new, old);
+ if (ret < 0)
+ return ret;
+ }
+ }
- current->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
+ new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
+ return 0;
}
-int cap_bprm_secureexec (struct linux_binprm *bprm)
+/**
+ * cap_bprm_secureexec - Determine whether a secure execution is required
+ * @bprm: The execution parameters
+ *
+ * Determine whether a secure execution is required, return 1 if it is, and 0
+ * if it is not.
+ *
+ * The credentials have been committed by this point, and so are no longer
+ * available through @bprm->cred.
+ */
+int cap_bprm_secureexec(struct linux_binprm *bprm)
{
- if (current->uid != 0) {
+ const struct cred *cred = current_cred();
+
+ if (cred->uid != 0) {
if (bprm->cap_effective)
return 1;
- if (!cap_isclear(bprm->cap_post_exec_permitted))
+ if (!cap_isclear(cred->cap_permitted))
return 1;
}
- return (current->euid != current->uid ||
- current->egid != current->gid);
+ return (cred->euid != cred->uid ||
+ cred->egid != cred->gid);
}
+/**
+ * cap_inode_setxattr - Determine whether an xattr may be altered
+ * @dentry: The inode/dentry being altered
+ * @name: The name of the xattr to be changed
+ * @value: The value that the xattr will be changed to
+ * @size: The size of value
+ * @flags: The replacement flag
+ *
+ * Determine whether an xattr may be altered or set on an inode, returning 0 if
+ * permission is granted, -ve if denied.
+ *
+ * This is used to make sure security xattrs don't get updated or set by those
+ * who aren't privileged to do so.
+ */
int cap_inode_setxattr(struct dentry *dentry, const char *name,
const void *value, size_t size, int flags)
{
@@ -418,28 +585,42 @@ int cap_inode_setxattr(struct dentry *dentry, const char *name,
if (!capable(CAP_SETFCAP))
return -EPERM;
return 0;
- } else if (!strncmp(name, XATTR_SECURITY_PREFIX,
+ }
+
+ if (!strncmp(name, XATTR_SECURITY_PREFIX,
sizeof(XATTR_SECURITY_PREFIX) - 1) &&
!capable(CAP_SYS_ADMIN))
return -EPERM;
return 0;
}
+/**
+ * cap_inode_removexattr - Determine whether an xattr may be removed
+ * @dentry: The inode/dentry being altered
+ * @name: The name of the xattr to be changed
+ *
+ * Determine whether an xattr may be removed from an inode, returning 0 if
+ * permission is granted, -ve if denied.
+ *
+ * This is used to make sure security xattrs don't get removed by those who
+ * aren't privileged to remove them.
+ */
int cap_inode_removexattr(struct dentry *dentry, const char *name)
{
if (!strcmp(name, XATTR_NAME_CAPS)) {
if (!capable(CAP_SETFCAP))
return -EPERM;
return 0;
- } else if (!strncmp(name, XATTR_SECURITY_PREFIX,
+ }
+
+ if (!strncmp(name, XATTR_SECURITY_PREFIX,
sizeof(XATTR_SECURITY_PREFIX) - 1) &&
!capable(CAP_SYS_ADMIN))
return -EPERM;
return 0;
}
-/* moved from kernel/sys.c. */
-/*
+/*
* cap_emulate_setxuid() fixes the effective / permitted capabilities of
* a process after a call to setuid, setreuid, or setresuid.
*
@@ -453,10 +634,10 @@ int cap_inode_removexattr(struct dentry *dentry, const char *name)
* 3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective
* capabilities are set to the permitted capabilities.
*
- * fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should
+ * fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should
* never happen.
*
- * -astor
+ * -astor
*
* cevans - New behaviour, Oct '99
* A process may, via prctl(), elect to keep its capabilities when it
@@ -468,61 +649,60 @@ int cap_inode_removexattr(struct dentry *dentry, const char *name)
* files..
* Thanks to Olaf Kirch and Peter Benie for spotting this.
*/
-static inline void cap_emulate_setxuid (int old_ruid, int old_euid,
- int old_suid)
+static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old)
{
- if ((old_ruid == 0 || old_euid == 0 || old_suid == 0) &&
- (current->uid != 0 && current->euid != 0 && current->suid != 0) &&
+ if ((old->uid == 0 || old->euid == 0 || old->suid == 0) &&
+ (new->uid != 0 && new->euid != 0 && new->suid != 0) &&
!issecure(SECURE_KEEP_CAPS)) {
- cap_clear (current->cap_permitted);
- cap_clear (current->cap_effective);
- }
- if (old_euid == 0 && current->euid != 0) {
- cap_clear (current->cap_effective);
- }
- if (old_euid != 0 && current->euid == 0) {
- current->cap_effective = current->cap_permitted;
+ cap_clear(new->cap_permitted);
+ cap_clear(new->cap_effective);
}
+ if (old->euid == 0 && new->euid != 0)
+ cap_clear(new->cap_effective);
+ if (old->euid != 0 && new->euid == 0)
+ new->cap_effective = new->cap_permitted;
}
-int cap_task_post_setuid (uid_t old_ruid, uid_t old_euid, uid_t old_suid,
- int flags)
+/**
+ * cap_task_fix_setuid - Fix up the results of setuid() call
+ * @new: The proposed credentials
+ * @old: The current task's current credentials
+ * @flags: Indications of what has changed
+ *
+ * Fix up the results of setuid() call before the credential changes are
+ * actually applied, returning 0 to grant the changes, -ve to deny them.
+ */
+int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags)
{
switch (flags) {
case LSM_SETID_RE:
case LSM_SETID_ID:
case LSM_SETID_RES:
- /* Copied from kernel/sys.c:setreuid/setuid/setresuid. */
- if (!issecure (SECURE_NO_SETUID_FIXUP)) {
- cap_emulate_setxuid (old_ruid, old_euid, old_suid);
- }
+ /* juggle the capabilities to follow [RES]UID changes unless
+ * otherwise suppressed */
+ if (!issecure(SECURE_NO_SETUID_FIXUP))
+ cap_emulate_setxuid(new, old);
break;
- case LSM_SETID_FS:
- {
- uid_t old_fsuid = old_ruid;
- /* Copied from kernel/sys.c:setfsuid. */
-
- /*
- * FIXME - is fsuser used for all CAP_FS_MASK capabilities?
- * if not, we might be a bit too harsh here.
- */
-
- if (!issecure (SECURE_NO_SETUID_FIXUP)) {
- if (old_fsuid == 0 && current->fsuid != 0) {
- current->cap_effective =
- cap_drop_fs_set(
- current->cap_effective);
- }
- if (old_fsuid != 0 && current->fsuid == 0) {
- current->cap_effective =
- cap_raise_fs_set(
- current->cap_effective,
- current->cap_permitted);
- }
- }
- break;
+ case LSM_SETID_FS:
+ /* juggle the capabilties to follow FSUID changes, unless
+ * otherwise suppressed
+ *
+ * FIXME - is fsuser used for all CAP_FS_MASK capabilities?
+ * if not, we might be a bit too harsh here.
+ */
+ if (!issecure(SECURE_NO_SETUID_FIXUP)) {
+ if (old->fsuid == 0 && new->fsuid != 0)
+ new->cap_effective =
+ cap_drop_fs_set(new->cap_effective);
+
+ if (old->fsuid != 0 && new->fsuid == 0)
+ new->cap_effective =
+ cap_raise_fs_set(new->cap_effective,
+ new->cap_permitted);
}
+ break;
+
default:
return -EINVAL;
}
@@ -543,42 +723,71 @@ int cap_task_post_setuid (uid_t old_ruid, uid_t old_euid, uid_t old_suid,
*/
static int cap_safe_nice(struct task_struct *p)
{
- if (!cap_issubset(p->cap_permitted, current->cap_permitted) &&
- !capable(CAP_SYS_NICE))
+ int is_subset;
+
+ rcu_read_lock();
+ is_subset = cap_issubset(__task_cred(p)->cap_permitted,
+ current_cred()->cap_permitted);
+ rcu_read_unlock();
+
+ if (!is_subset && !capable(CAP_SYS_NICE))
return -EPERM;
return 0;
}
-int cap_task_setscheduler (struct task_struct *p, int policy,
+/**
+ * cap_task_setscheduler - Detemine if scheduler policy change is permitted
+ * @p: The task to affect
+ * @policy: The policy to effect
+ * @lp: The parameters to the scheduling policy
+ *
+ * Detemine if the requested scheduler policy change is permitted for the
+ * specified task, returning 0 if permission is granted, -ve if denied.
+ */
+int cap_task_setscheduler(struct task_struct *p, int policy,
struct sched_param *lp)
{
return cap_safe_nice(p);
}
-int cap_task_setioprio (struct task_struct *p, int ioprio)
+/**
+ * cap_task_ioprio - Detemine if I/O priority change is permitted
+ * @p: The task to affect
+ * @ioprio: The I/O priority to set
+ *
+ * Detemine if the requested I/O priority change is permitted for the specified
+ * task, returning 0 if permission is granted, -ve if denied.
+ */
+int cap_task_setioprio(struct task_struct *p, int ioprio)
{
return cap_safe_nice(p);
}
-int cap_task_setnice (struct task_struct *p, int nice)
+/**
+ * cap_task_ioprio - Detemine if task priority change is permitted
+ * @p: The task to affect
+ * @nice: The nice value to set
+ *
+ * Detemine if the requested task priority change is permitted for the
+ * specified task, returning 0 if permission is granted, -ve if denied.
+ */
+int cap_task_setnice(struct task_struct *p, int nice)
{
return cap_safe_nice(p);
}
/*
- * called from kernel/sys.c for prctl(PR_CABSET_DROP)
- * done without task_capability_lock() because it introduces
- * no new races - i.e. only another task doing capget() on
- * this task could get inconsistent info. There can be no
- * racing writer bc a task can only change its own caps.
+ * Implement PR_CAPBSET_DROP. Attempt to remove the specified capability from
+ * the current task's bounding set. Returns 0 on success, -ve on error.
*/
-static long cap_prctl_drop(unsigned long cap)
+static long cap_prctl_drop(struct cred *new, unsigned long cap)
{
if (!capable(CAP_SETPCAP))
return -EPERM;
if (!cap_valid(cap))
return -EINVAL;
- cap_lower(current->cap_bset, cap);
+
+ cap_lower(new->cap_bset, cap);
return 0;
}
@@ -598,22 +807,42 @@ int cap_task_setnice (struct task_struct *p, int nice)
}
#endif
+/**
+ * cap_task_prctl - Implement process control functions for this security module
+ * @option: The process control function requested
+ * @arg2, @arg3, @arg4, @arg5: The argument data for this function
+ *
+ * Allow process control functions (sys_prctl()) to alter capabilities; may
+ * also deny access to other functions not otherwise implemented here.
+ *
+ * Returns 0 or +ve on success, -ENOSYS if this function is not implemented
+ * here, other -ve on error. If -ENOSYS is returned, sys_prctl() and other LSM
+ * modules will consider performing the function.
+ */
int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
- unsigned long arg4, unsigned long arg5, long *rc_p)
+ unsigned long arg4, unsigned long arg5)
{
+ struct cred *new;
long error = 0;
+ new = prepare_creds();
+ if (!new)
+ return -ENOMEM;
+
switch (option) {
case PR_CAPBSET_READ:
+ error = -EINVAL;
if (!cap_valid(arg2))
- error = -EINVAL;
- else
- error = !!cap_raised(current->cap_bset, arg2);
- break;
+ goto error;
+ error = !!cap_raised(new->cap_bset, arg2);
+ goto no_change;
+
#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
case PR_CAPBSET_DROP:
- error = cap_prctl_drop(arg2);
- break;
+ error = cap_prctl_drop(new, arg2);
+ if (error < 0)
+ goto error;
+ goto changed;
/*
* The next four prctl's remain to assist with transitioning a
@@ -635,12 +864,12 @@ int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
* capability-based-privilege environment.
*/
case PR_SET_SECUREBITS:
- if ((((current->securebits & SECURE_ALL_LOCKS) >> 1)
- & (current->securebits ^ arg2)) /*[1]*/
- || ((current->securebits & SECURE_ALL_LOCKS
- & ~arg2)) /*[2]*/
- || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/
- || (cap_capable(current, CAP_SETPCAP) != 0)) { /*[4]*/
+ error = -EPERM;
+ if ((((new->securebits & SECURE_ALL_LOCKS) >> 1)
+ & (new->securebits ^ arg2)) /*[1]*/
+ || ((new->securebits & SECURE_ALL_LOCKS & ~arg2)) /*[2]*/
+ || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/
+ || (cap_capable(current, CAP_SETPCAP, SECURITY_CAP_AUDIT) != 0) /*[4]*/
/*
* [1] no changing of bits that are locked
* [2] no unlocking of locks
@@ -648,65 +877,80 @@ int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
* [4] doing anything requires privilege (go read about
* the "sendmail capabilities bug")
*/
- error = -EPERM; /* cannot change a locked bit */
- } else {
- current->securebits = arg2;
- }
- break;
+ )
+ /* cannot change a locked bit */
+ goto error;
+ new->securebits = arg2;
+ goto changed;
+
case PR_GET_SECUREBITS:
- error = current->securebits;
- break;
+ error = new->securebits;
+ goto no_change;
#endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */
case PR_GET_KEEPCAPS:
if (issecure(SECURE_KEEP_CAPS))
error = 1;
- break;
+ goto no_change;
+
case PR_SET_KEEPCAPS:
+ error = -EINVAL;
if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */
- error = -EINVAL;
- else if (issecure(SECURE_KEEP_CAPS_LOCKED))
- error = -EPERM;
- else if (arg2)
- current->securebits |= issecure_mask(SECURE_KEEP_CAPS);
+ goto error;
+ error = -EPERM;
+ if (issecure(SECURE_KEEP_CAPS_LOCKED))
+ goto error;
+ if (arg2)
+ new->securebits |= issecure_mask(SECURE_KEEP_CAPS);
else
- current->securebits &=
- ~issecure_mask(SECURE_KEEP_CAPS);
- break;
+ new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
+ goto changed;
default:
/* No functionality available - continue with default */
- return 0;
+ error = -ENOSYS;
+ goto error;
}
/* Functionality provided */
- *rc_p = error;
- return 1;
-}
+changed:
+ return commit_creds(new);
-void cap_task_reparent_to_init (struct task_struct *p)
-{
- cap_set_init_eff(p->cap_effective);
- cap_clear(p->cap_inheritable);
- cap_set_full(p->cap_permitted);
- p->securebits = SECUREBITS_DEFAULT;
- return;
+no_change:
+ error = 0;
+error:
+ abort_creds(new);
+ return error;
}
-int cap_syslog (int type)
+/**
+ * cap_syslog - Determine whether syslog function is permitted
+ * @type: Function requested
+ *
+ * Determine whether the current process is permitted to use a particular
+ * syslog function, returning 0 if permission is granted, -ve if not.
+ */
+int cap_syslog(int type)
{
if ((type != 3 && type != 10) && !capable(CAP_SYS_ADMIN))
return -EPERM;
return 0;
}
+/**
+ * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted
+ * @mm: The VM space in which the new mapping is to be made
+ * @pages: The size of the mapping
+ *
+ * Determine whether the allocation of a new virtual mapping by the current
+ * task is permitted, returning 0 if permission is granted, -ve if not.
+ */
int cap_vm_enough_memory(struct mm_struct *mm, long pages)
{
int cap_sys_admin = 0;
- if (cap_capable(current, CAP_SYS_ADMIN) == 0)
+ if (cap_capable(current, CAP_SYS_ADMIN, SECURITY_CAP_NOAUDIT) == 0)
cap_sys_admin = 1;
return __vm_enough_memory(mm, pages, cap_sys_admin);
}
-