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Commit 1d045980 authored by David Howells's avatar David Howells Committed by James Morris
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CRED: Prettify commoncap.c 

Prettify commoncap.c.
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Acked-by: default avatarSerge Hallyn <serue@us.ibm.com>
Reviewed-by: default avatarJames Morris <jmorris@namei.org>
Signed-off-by: default avatarJames Morris <jmorris@namei.org>
parent a6f76f23
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Showing with 248 additions and 52 deletions
security/commoncap.c
View file @ 1d045980
......@@ -40,14 +40,21 @@ 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 audit)
{
......@@ -60,6 +67,14 @@ int cap_capable(struct task_struct *tsk, int cap, int audit)
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))
......@@ -67,6 +82,15 @@ 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)
{
int ret = 0;
......@@ -80,6 +104,13 @@ int cap_ptrace_may_access(struct task_struct *child, unsigned int mode)
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)
{
int ret = 0;
......@@ -93,7 +124,17 @@ int cap_ptrace_traceme(struct task_struct *parent)
return ret;
}
int cap_capget (struct task_struct *target, kernel_cap_t *effective,
/**
* 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;
......@@ -108,30 +149,35 @@ int cap_capget (struct task_struct *target, kernel_cap_t *effective,
return 0;
}
#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
/*
* 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, SECURITY_CAP_AUDIT) != 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_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 */
/**
* 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,
......@@ -165,6 +211,9 @@ int cap_capset(struct cred *new,
return 0;
}
/*
* Clear proposed capability sets for execve().
*/
static inline void bprm_clear_caps(struct linux_binprm *bprm)
{
cap_clear(bprm->cred->cap_permitted);
......@@ -173,6 +222,17 @@ static inline void bprm_clear_caps(struct linux_binprm *bprm)
#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;
......@@ -187,6 +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;
......@@ -197,6 +265,10 @@ int cap_inode_killpriv(struct dentry *dentry)
return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS);
}
/*
* 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)
......@@ -232,6 +304,9 @@ static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps,
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;
......@@ -283,7 +358,11 @@ int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data
return 0;
}
/* Locate any VFS capabilities: */
/*
* 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;
......@@ -342,7 +421,31 @@ static inline int get_file_caps(struct linux_binprm *bprm, bool *effective)
#endif
/*
* set up the new credentials for an exec'd task
* 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)
{
......@@ -430,10 +533,15 @@ int cap_bprm_set_creds(struct linux_binprm *bprm)
return 0;
}
/*
* determine whether a secure execution is required
* - the creds have been committed at this point, and are no longer available
* through 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)
{
......@@ -450,6 +558,20 @@ int cap_bprm_secureexec(struct linux_binprm *bprm)
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)
{
......@@ -457,27 +579,41 @@ 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.
......@@ -521,35 +657,46 @@ static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old)
new->cap_effective = new->cap_permitted;
}
/**
* 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. */
/* 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:
/* Copied from kernel/sys.c:setfsuid. */
/*
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) {
if (old->fsuid == 0 && new->fsuid != 0)
new->cap_effective =
cap_drop_fs_set(new->cap_effective);
}
if (old->fsuid != 0 && new->fsuid == 0) {
if (old->fsuid != 0 && new->fsuid == 0)
new->cap_effective =
cap_raise_fs_set(new->cap_effective,
new->cap_permitted);
}
}
break;
default:
return -EINVAL;
}
......@@ -582,28 +729,50 @@ static int cap_safe_nice(struct task_struct *p)
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(struct cred *new, unsigned long cap)
{
......@@ -632,6 +801,18 @@ 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)
{
......@@ -737,13 +918,28 @@ int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
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;
......
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