cregit-Linux how code gets into the kernel

Release 4.7 security/commoncap.c

Directory: security
/* Common capabilities, needed by capability.o.
 *
 *      This program is free software; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License as published by
 *      the Free Software Foundation; either version 2 of the License, or
 *      (at your option) any later version.
 *
 */

#include <linux/capability.h>
#include <linux/audit.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/lsm_hooks.h>
#include <linux/file.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
#include <linux/skbuff.h>
#include <linux/netlink.h>
#include <linux/ptrace.h>
#include <linux/xattr.h>
#include <linux/hugetlb.h>
#include <linux/mount.h>
#include <linux/sched.h>
#include <linux/prctl.h>
#include <linux/securebits.h>
#include <linux/user_namespace.h>
#include <linux/binfmts.h>
#include <linux/personality.h>

/*
 * If a non-root user executes a setuid-root binary in
 * !secure(SECURE_NOROOT) mode, then we raise capabilities.
 * However if fE is also set, then the intent is for only
 * the file capabilities to be applied, and the setuid-root
 * bit is left on either to change the uid (plausible) or
 * to get full privilege on a kernel without file capabilities
 * support.  So in that case we do not raise capabilities.
 *
 * Warn if that happens, once per boot.
 */

static void warn_setuid_and_fcaps_mixed(const char *fname) { static int warned; if (!warned) { printk(KERN_INFO "warning: `%s' has both setuid-root and" " effective capabilities. Therefore not raising all" " capabilities.\n", fname); warned = 1; } }

Contributors

PersonTokensPropCommitsCommitProp
serge hallynserge hallyn3597.22%150.00%
david howellsdavid howells12.78%150.00%
Total36100.00%2100.00%

/** * cap_capable - Determine whether a task has a particular effective capability * @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 * * 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_has_capability() cannot be used like the kernel's capable() * and has_capability() functions. That is, it has the reverse semantics: * 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(const struct cred *cred, struct user_namespace *targ_ns, int cap, int audit) { struct user_namespace *ns = targ_ns; /* See if cred has the capability in the target user namespace * by examining the target user namespace and all of the target * user namespace's parents. */ for (;;) { /* Do we have the necessary capabilities? */ if (ns == cred->user_ns) return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM; /* Have we tried all of the parent namespaces? */ if (ns == &init_user_ns) return -EPERM; /* * The owner of the user namespace in the parent of the * user namespace has all caps. */ if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid)) return 0; /* * If you have a capability in a parent user ns, then you have * it over all children user namespaces as well. */ ns = ns->parent; } /* We never get here */ }

Contributors

PersonTokensPropCommitsCommitProp
eric w. biedermaneric w. biederman4137.96%225.00%
serge hallynserge hallyn3532.41%112.50%
chris wrightchris wright1614.81%112.50%
david howellsdavid howells1312.04%337.50%
eric pariseric paris32.78%112.50%
Total108100.00%8100.00%

/** * 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(const struct timespec64 *ts, const struct timezone *tz) { if (!capable(CAP_SYS_TIME)) return -EPERM; return 0; }

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michael a. halcrowmichael a. halcrow2990.62%133.33%
richard cochranrichard cochran26.25%133.33%
baolin wangbaolin wang13.12%133.33%
Total32100.00%3100.00%

/** * cap_ptrace_access_check - Determine whether the current process may access * another * @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; const kernel_cap_t *caller_caps; rcu_read_lock(); cred = current_cred(); child_cred = __task_cred(child); if (mode & PTRACE_MODE_FSCREDS) caller_caps = &cred->cap_effective; else caller_caps = &cred->cap_permitted; if (cred->user_ns == child_cred->user_ns && cap_issubset(child_cred->cap_permitted, *caller_caps)) goto out; if (ns_capable(child_cred->user_ns, CAP_SYS_PTRACE)) goto out; ret = -EPERM; out: rcu_read_unlock(); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
serge hallynserge hallyn4638.66%111.11%
jann hornjann horn2823.53%111.11%
david howellsdavid howells2117.65%444.44%
chris wrightchris wright1915.97%111.11%
stephen d. smalleystephen d. smalley43.36%111.11%
ingo molnaringo molnar10.84%111.11%
Total119100.00%9100.00%

/** * 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(); cred = __task_cred(parent); child_cred = current_cred(); if (cred->user_ns == child_cred->user_ns && cap_issubset(child_cred->cap_permitted, cred->cap_permitted)) goto out; if (has_ns_capability(parent, child_cred->user_ns, CAP_SYS_PTRACE)) goto out; ret = -EPERM; out: rcu_read_unlock(); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
serge hallynserge hallyn4751.09%120.00%
david howellsdavid howells4447.83%360.00%
chris wrightchris wright11.09%120.00%
Total92100.00%5100.00%

/** * 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. */ rcu_read_lock(); cred = __task_cred(target); *effective = cred->cap_effective; *inheritable = cred->cap_inheritable; *permitted = cred->cap_permitted; rcu_read_unlock(); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
chris wrightchris wright4466.67%133.33%
david howellsdavid howells2233.33%266.67%
Total66100.00%3100.00%

/* * 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) { /* they are so limited unless the current task has the CAP_SETPCAP * capability */ if (cap_capable(current_cred(), current_cred()->user_ns, CAP_SETPCAP, SECURITY_CAP_AUDIT) == 0) return 0; return 1; }

Contributors

PersonTokensPropCommitsCommitProp
andrew g. morganandrew g. morgan1954.29%342.86%
david howellsdavid howells925.71%228.57%
serge hallynserge hallyn514.29%114.29%
eric pariseric paris25.71%114.29%
Total35100.00%7100.00%

/** * 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(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, old->cap_permitted)) return -EPERM; /* verify the _new_Effective_ is a subset of the _new_Permitted_ */ if (!cap_issubset(*effective, *permitted)) return -EPERM; new->cap_effective = *effective; new->cap_inheritable = *inheritable; new->cap_permitted = *permitted; /* * Mask off ambient bits that are no longer both permitted and * inheritable. */ new->cap_ambient = cap_intersect(new->cap_ambient, cap_intersect(*permitted, *inheritable)); if (WARN_ON(!cap_ambient_invariant_ok(new))) return -EINVAL; return 0; }

Contributors

PersonTokensPropCommitsCommitProp
chris wrightchris wright8949.72%114.29%
andy lutomirskiandy lutomirski3620.11%114.29%
david howellsdavid howells2715.08%342.86%
serge hallynserge hallyn2312.85%114.29%
andrew g. morganandrew g. morgan42.23%114.29%
Total179100.00%7100.00%

/* * Clear proposed capability sets for execve(). */
static inline void bprm_clear_caps(struct linux_binprm *bprm) { cap_clear(bprm->cred->cap_permitted); bprm->cap_effective = false; }

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PersonTokensPropCommitsCommitProp
chris wrightchris wright1762.96%133.33%
serge hallynserge hallyn725.93%133.33%
david howellsdavid howells311.11%133.33%
Total27100.00%3100.00%

/** * 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 = d_backing_inode(dentry); int error; if (!inode->i_op->getxattr) return 0; error = inode->i_op->getxattr(dentry, inode, XATTR_NAME_CAPS, NULL, 0); if (error <= 0) return 0; return 1; }

Contributors

PersonTokensPropCommitsCommitProp
serge hallynserge hallyn5583.33%125.00%
chris wrightchris wright69.09%125.00%
david howellsdavid howells34.55%125.00%
al viroal viro23.03%125.00%
Total66100.00%4100.00%

/** * 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 = d_backing_inode(dentry); if (!inode->i_op->removexattr) return 0; return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS); }

Contributors

PersonTokensPropCommitsCommitProp
serge hallynserge hallyn3681.82%133.33%
chris wrightchris wright511.36%133.33%
david howellsdavid howells36.82%133.33%
Total44100.00%3100.00%

/* * 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, bool *has_cap) { struct cred *new = bprm->cred; unsigned i; int ret = 0; if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE) *effective = true; if (caps->magic_etc & VFS_CAP_REVISION_MASK) *has_cap = true; CAP_FOR_EACH_U32(i) { __u32 permitted = caps->permitted.cap[i]; __u32 inheritable = caps->inheritable.cap[i]; /* * pP' = (X & fP) | (pI & fI) * The addition of pA' is handled later. */ 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; }

Contributors

PersonTokensPropCommitsCommitProp
eric pariseric paris10665.03%114.29%
david howellsdavid howells2615.95%228.57%
zhi lizhi li1710.43%114.29%
serge hallynserge hallyn116.75%114.29%
andrew g. morganandrew g. morgan21.23%114.29%
andy lutomirskiandy lutomirski10.61%114.29%
Total163100.00%7100.00%

/* * 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 = d_backing_inode(dentry); __u32 magic_etc; unsigned tocopy, i; int size; struct vfs_cap_data caps; memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data)); if (!inode || !inode->i_op->getxattr) return -ENODATA; size = inode->i_op->getxattr((struct dentry *)dentry, inode, 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; cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps.magic_etc); switch (magic_etc & VFS_CAP_REVISION_MASK) { case VFS_CAP_REVISION_1: if (size != XATTR_CAPS_SZ_1) return -EINVAL; tocopy = VFS_CAP_U32_1; break; case VFS_CAP_REVISION_2: if (size != XATTR_CAPS_SZ_2) return -EINVAL; tocopy = VFS_CAP_U32_2; break; default: return -EINVAL; } CAP_FOR_EACH_U32(i) { 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); } cpu_caps->permitted.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK; cpu_caps->inheritable.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK; return 0; }

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PersonTokensPropCommitsCommitProp
eric pariseric paris13749.64%222.22%
andrew g. morganandrew g. morgan8229.71%222.22%
serge hallynserge hallyn4215.22%111.11%
chris wrightchris wright62.17%111.11%
andrew mortonandrew morton41.45%111.11%
david howellsdavid howells31.09%111.11%
al viroal viro20.72%111.11%
Total276100.00%9100.00%

/* * 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, bool *has_cap) { int rc = 0; struct cpu_vfs_cap_data vcaps; bprm_clear_caps(bprm); if (!file_caps_enabled) return 0; if (bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID) return 0; rc = get_vfs_caps_from_disk(bprm->file->f_path.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; } rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective, has_cap); if (rc == -EINVAL) printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n", __func__, rc, bprm->filename); out: if (rc) bprm_clear_caps(bprm); return rc; }

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PersonTokensPropCommitsCommitProp
serge hallynserge hallyn8047.90%327.27%
david howellsdavid howells2716.17%19.09%
eric pariseric paris2514.97%19.09%
chris wrightchris wright1710.18%19.09%
al viroal viro84.79%327.27%
zhi lizhi li63.59%19.09%
andrew g. morganandrew g. morgan42.40%19.09%
Total167100.00%11100.00%

/** * 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, has_cap = false, is_setid; int ret; kuid_t root_uid; if (WARN_ON(!cap_ambient_invariant_ok(old))) return -EPERM; effective = false; ret = get_file_caps(bprm, &effective, &has_cap); if (ret < 0) return ret; root_uid = make_kuid(new->user_ns, 0); if (!issecure(SECURE_NOROOT)) { /* * If the legacy file capability is set, then don't set privs * for a setuid root binary run by a non-root user. Do set it * for a root user just to cause least surprise to an admin. */ if (has_cap && !uid_eq(new->uid, root_uid) && uid_eq(new->euid, root_uid)) { warn_setuid_and_fcaps_mixed(bprm->filename); goto skip; } /* * To support inheritance of root-permissions and suid-root * 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 (uid_eq(new->euid, root_uid) || uid_eq(new->uid, root_uid)) { /* pP' = (cap_bset & ~0) | (pI & ~0) */ new->cap_permitted = cap_combine(old->cap_bset, old->cap_inheritable); } if (uid_eq(new->euid, root_uid)) effective = true; } skip: /* if we have fs caps, clear dangerous personality flags */ if (!cap_issubset(new->cap_permitted, old->cap_permitted)) bprm->per_clear |= PER_CLEAR_ON_SETID; /* Don't let someone trace a set[ug]id/setpcap binary with the revised * credentials unless they have the appropriate permit. * * In addition, if NO_NEW_PRIVS, then ensure we get no new privs. */ is_setid = !uid_eq(new->euid, old->uid) || !gid_eq(new->egid, old->gid); if ((is_setid || !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) || (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)) { new->euid = new->uid; new->egid = new->gid; } new->cap_permitted = cap_intersect(new->cap_permitted, old->cap_permitted); } new->suid = new->fsuid = new->euid; new->sgid = new->fsgid = new->egid; /* File caps or setid cancels ambient. */ if (has_cap || is_setid) cap_clear(new->cap_ambient); /* * Now that we've computed pA', update pP' to give: * pP' = (X & fP) | (pI & fI) | pA' */ new->cap_permitted = cap_combine(new->cap_permitted, new->cap_ambient); /* * Set pE' = (fE ? pP' : pA'). Because pA' is zero if fE is set, * this is the same as pE' = (fE ? pP' : 0) | pA'. */ if (effective) new->cap_effective = new->cap_permitted; else new->cap_effective = new->cap_ambient; if (WARN_ON(!cap_ambient_invariant_ok(new))) return -EPERM; bprm->cap_effective = effective; /* * 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_issubset(new->cap_effective, new->cap_ambient)) { if (!cap_issubset(CAP_FULL_SET, new->cap_effective) || !uid_eq(new->euid, root_uid) || !uid_eq(new->uid, root_uid) || issecure(SECURE_NOROOT)) { ret = audit_log_bprm_fcaps(bprm, new, old); if (ret < 0) return ret; } } new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS); if (WARN_ON(!cap_ambient_invariant_ok(new))) return -EPERM; return 0; }

Contributors

PersonTokensPropCommitsCommitProp
david howellsdavid howells12924.67%316.67%
andy lutomirskiandy lutomirski10319.69%211.11%
serge hallynserge hallyn7313.96%316.67%
eric w. biedermaneric w. biederman6211.85%15.56%
eric pariseric paris6011.47%211.11%
andrew mortonandrew morton5510.52%211.11%
andrew g. morganandrew g. morgan224.21%316.67%
chris wrightchris wright132.49%15.56%
zhi lizhi li61.15%15.56%
Total523100.00%18100.00%

/** * 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) { const struct cred *cred = current_cred(); kuid_t root_uid = make_kuid(cred->user_ns, 0); if (!uid_eq(cred->uid, root_uid)) { if (bprm->cap_effective) return 1; if (!cap_issubset(cred->cap_permitted, cred->cap_ambient)) return 1; } return (!uid_eq(cred->euid, cred->uid) || !gid_eq(cred->egid, cred->gid)); }

Contributors

PersonTokensPropCommitsCommitProp
eric w. biedermaneric w. biederman2828.57%114.29%
david howellsdavid howells2626.53%342.86%
serge hallynserge hallyn2424.49%114.29%
chris wrightchris wright1515.31%114.29%
andy lutomirskiandy lutomirski55.10%114.29%
Total98100.00%7100.00%

/** * 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) { if (!strcmp(name, XATTR_NAME_CAPS)) { if (!capable(CAP_SETFCAP)) return -EPERM; return 0; } if (!strncmp(name, XATTR_SECURITY_PREFIX, sizeof(XATTR_SECURITY_PREFIX) - 1) && !capable(CAP_SYS_ADMIN)) return -EPERM; return 0; }

Contributors

PersonTokensPropCommitsCommitProp
andrew mortonandrew morton5465.06%133.33%
serge hallynserge hallyn2732.53%133.33%
david howellsdavid howells22.41%133.33%
Total83100.00%3100.00%

/** * 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; } if (!strncmp(name, XATTR_SECURITY_PREFIX, sizeof(XATTR_SECURITY_PREFIX) - 1) && !capable(CAP_SYS_ADMIN)) return -EPERM; return 0; }

Contributors

PersonTokensPropCommitsCommitProp
andrew mortonandrew morton4461.11%133.33%
serge hallynserge hallyn2737.50%133.33%
david howellsdavid howells11.39%133.33%
Total72100.00%3100.00%

/* * cap_emulate_setxuid() fixes the effective / permitted capabilities of * a process after a call to setuid, setreuid, or setresuid. * * 1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of * {r,e,s}uid != 0, the permitted and effective capabilities are * cleared. * * 2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective * capabilities of the process are cleared. * * 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 * never happen. * * -astor * * cevans - New behaviour, Oct '99 * A process may, via prctl(), elect to keep its capabilities when it * calls setuid() and switches away from uid==0. Both permitted and * effective sets will be retained. * Without this change, it was impossible for a daemon to drop only some * of its privilege. The call to setuid(!=0) would drop all privileges! * Keeping uid 0 is not an option because uid 0 owns too many vital * files.. * Thanks to Olaf Kirch and Peter Benie for spotting this. */
static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old) { kuid_t root_uid = make_kuid(old->user_ns, 0); if ((uid_eq(old->uid, root_uid) || uid_eq(old->euid, root_uid) || uid_eq(old->suid, root_uid)) && (!uid_eq(new->uid, root_uid) && !uid_eq(new->euid, root_uid) && !uid_eq(new->suid, root_uid))) { if (!issecure(SECURE_KEEP_CAPS)) { cap_clear(new->cap_permitted); cap_clear(new->cap_effective); } /* * Pre-ambient programs expect setresuid to nonroot followed * by exec to drop capabilities. We should make sure that * this remains the case. */ cap_clear(new->cap_ambient); } if (uid_eq(old->euid, root_uid) && !uid_eq(new->euid, root_uid)) cap_clear(new->cap_effective); if (!uid_eq(old->euid, root_uid) && uid_eq(new->euid, root_uid)) new->cap_effective = new->cap_permitted; }

Contributors

PersonTokensPropCommitsCommitProp
eric w. biedermaneric w. biederman6736.41%116.67%
chris wrightchris wright5630.43%116.67%
david howellsdavid howells4423.91%233.33%
andy lutomirskiandy lutomirski137.07%116.67%
andrew g. morganandrew g. morgan42.17%116.67%
Total184100.00%6100.00%

/** * 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: /* 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: /* 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)) { kuid_t root_uid = make_kuid(old->user_ns, 0); if (uid_eq(old->fsuid, root_uid) && !uid_eq(new->fsuid, root_uid)) new->cap_effective = cap_drop_fs_set(new->cap_effective); if (!uid_eq(old->fsuid, root_uid) && uid_eq(new->fsuid, root_uid)) new->cap_effective = cap_raise_fs_set(new->cap_effective, new->cap_permitted); } break; default: return -EINVAL; } return 0; }

Contributors

PersonTokensPropCommitsCommitProp
serge hallynserge hallyn8051.95%116.67%
eric w. biedermaneric w. biederman3422.08%116.67%
david howellsdavid howells3120.13%350.00%
andrew g. morganandrew g. morgan95.84%116.67%
Total154100.00%6100.00%

/* * Rationale: code calling task_setscheduler, task_setioprio, and * task_setnice, assumes that * . if capable(cap_sys_nice), then those actions should be allowed * . if not capable(cap_sys_nice), but acting on your own processes, * then those actions should be allowed * This is insufficient now since you can call code without suid, but * yet with increased caps. * So we check for increased caps on the target process. */
static int cap_safe_nice(struct task_struct *p) { int is_subset, ret = 0; rcu_read_lock(); is_subset = cap_issubset(__task_cred(p)->cap_permitted, current_cred()->cap_permitted); if (!is_subset && !ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) ret = -EPERM; rcu_read_unlock(); return ret; }

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serge hallynserge hallyn4770.15%250.00%
david howellsdavid howells2029.85%250.00%
Total67100.00%4100.00%

/** * cap_task_setscheduler - Detemine if scheduler policy change is permitted * @p: The task to affect * * 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) { return cap_safe_nice(p); }

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serge hallynserge hallyn16100.00%1100.00%
Total16100.00%1100.00%

/** * 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); }

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serge hallynserge hallyn19100.00%1100.00%
Total19100.00%1100.00%

/** * 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); }

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PersonTokensPropCommitsCommitProp
serge hallynserge hallyn1684.21%150.00%
chris wrightchris wright315.79%150.00%
Total19100.00%2100.00%

/* * 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 int cap_prctl_drop(unsigned long cap) { struct cred *new; if (!ns_capable(current_user_ns(), CAP_SETPCAP)) return -EPERM; if (!cap_valid(cap)) return -EINVAL; new = prepare_creds(); if (!new) return -ENOMEM; cap_lower(new->cap_bset, cap); return commit_creds(new); }

Contributors

PersonTokensPropCommitsCommitProp
serge hallynserge hallyn4056.34%116.67%
tetsuo handatetsuo handa2433.80%116.67%
eric w. biedermaneric w. biederman45.63%116.67%
david howellsdavid howells22.82%233.33%
andrew g. morganandrew g. morgan11.41%116.67%
Total71100.00%6100.00%

/** * 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