Increase the size of capability sets to 64 bits:
* bits 32-47 are "regular", i.e., present by default on non-root
processes;
* maintain compatibility with former kernel interface for capset()
and capget().
See <URL: http://www.madore.org/~david/linux/newcaps/ > for more
detailed explanations.
Signed-off-by: David A. Madore <[email protected]>
---
fs/open.c | 3 ++-
fs/proc/array.c | 6 +++---
include/linux/capability.h | 30 ++++++++++++++++++-----------
kernel/capability.c | 46 +++++++++++++++++++++++++++++++++++---------
security/commoncap.c | 16 +++++++++++----
security/dummy.c | 6 +++---
6 files changed, 75 insertions(+), 32 deletions(-)
diff --git a/fs/open.c b/fs/open.c
index 303f06d..e58a525 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -515,7 +515,8 @@ asmlinkage long sys_faccessat(int dfd, c
* but we cannot because user_path_walk can sleep.
*/
if (current->uid)
- cap_clear(current->cap_effective);
+ current->cap_effective = cap_intersect(current->cap_effective,
+ CAP_REGULAR_SET);
else
current->cap_effective = current->cap_permitted;
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 0b615d6..6724fc2 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -285,9 +285,9 @@ static inline char * task_sig(struct tas
static inline char *task_cap(struct task_struct *p, char *buffer)
{
- return buffer + sprintf(buffer, "CapInh:\t%016x\n"
- "CapPrm:\t%016x\n"
- "CapEff:\t%016x\n",
+ return buffer + sprintf(buffer, "CapInh:\t%016llx\n"
+ "CapPrm:\t%016llx\n"
+ "CapEff:\t%016llx\n",
cap_t(p->cap_inheritable),
cap_t(p->cap_permitted),
cap_t(p->cap_effective));
diff --git a/include/linux/capability.h b/include/linux/capability.h
index 6548b35..aa00b60 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -27,7 +27,8 @@ #include <linux/compiler.h>
library since the draft standard requires the use of malloc/free
etc.. */
-#define _LINUX_CAPABILITY_VERSION 0x19980330
+#define _LINUX_CAPABILITY_VERSION 0x20060903
+#define _LINUX_CAPABILITY_OLD_VERSION 0x19980330
typedef struct __user_cap_header_struct {
__u32 version;
@@ -35,10 +36,16 @@ typedef struct __user_cap_header_struct
} __user *cap_user_header_t;
typedef struct __user_cap_data_struct {
+ __u64 effective;
+ __u64 permitted;
+ __u64 inheritable;
+} __user *cap_user_data_t;
+
+typedef struct __user_cap_data_old_struct {
__u32 effective;
__u32 permitted;
__u32 inheritable;
-} __user *cap_user_data_t;
+} __user *cap_user_data_old_t;
#ifdef __KERNEL__
@@ -50,12 +57,12 @@ #include <asm/current.h>
#ifdef STRICT_CAP_T_TYPECHECKS
typedef struct kernel_cap_struct {
- __u32 cap;
+ __u64 cap;
} kernel_cap_t;
#else
-typedef __u32 kernel_cap_t;
+typedef __u64 kernel_cap_t;
#endif
@@ -310,12 +317,13 @@ #define cap_t(x) (x)
#endif
-#define CAP_EMPTY_SET to_cap_t(0)
-#define CAP_FULL_SET to_cap_t(~0)
-#define CAP_INIT_EFF_SET to_cap_t(~0 & ~CAP_TO_MASK(CAP_SETPCAP))
-#define CAP_INIT_INH_SET to_cap_t(0)
+#define CAP_EMPTY_SET to_cap_t(0ULL)
+#define CAP_FULL_SET to_cap_t(~0ULL)
+#define CAP_REGULAR_SET to_cap_t(0x0000ffff00000000ULL)
+#define CAP_INIT_EFF_SET to_cap_t(~0ULL)
+#define CAP_INIT_INH_SET to_cap_t(~0ULL)
-#define CAP_TO_MASK(x) (1 << (x))
+#define CAP_TO_MASK(x) (1ULL << (x))
#define cap_raise(c, flag) (cap_t(c) |= CAP_TO_MASK(flag))
#define cap_lower(c, flag) (cap_t(c) &= ~CAP_TO_MASK(flag))
#define cap_raised(c, flag) (cap_t(c) & CAP_TO_MASK(flag))
@@ -351,8 +359,8 @@ static inline kernel_cap_t cap_invert(ke
#define cap_isclear(c) (!cap_t(c))
#define cap_issubset(a,set) (!(cap_t(a) & ~cap_t(set)))
-#define cap_clear(c) do { cap_t(c) = 0; } while(0)
-#define cap_set_full(c) do { cap_t(c) = ~0; } while(0)
+#define cap_clear(c) do { cap_t(c) = 0ULL; } while(0)
+#define cap_set_full(c) do { cap_t(c) = ~0ULL; } while(0)
#define cap_mask(c,mask) do { cap_t(c) &= cap_t(mask); } while(0)
#define cap_is_fs_cap(c) (CAP_TO_MASK(c) & CAP_FS_MASK)
diff --git a/kernel/capability.c b/kernel/capability.c
index c7685ad..32b2521 100644
--- a/kernel/capability.c
+++ b/kernel/capability.c
@@ -52,7 +52,8 @@ asmlinkage long sys_capget(cap_user_head
if (get_user(version, &header->version))
return -EFAULT;
- if (version != _LINUX_CAPABILITY_VERSION) {
+ if (version != _LINUX_CAPABILITY_VERSION
+ && version != _LINUX_CAPABILITY_OLD_VERSION) {
if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
return -EFAULT;
return -EINVAL;
@@ -82,8 +83,18 @@ out:
read_unlock(&tasklist_lock);
spin_unlock(&task_capability_lock);
- if (!ret && copy_to_user(dataptr, &data, sizeof data))
- return -EFAULT;
+ if (!ret) {
+ if (version == _LINUX_CAPABILITY_OLD_VERSION) {
+ struct __user_cap_data_old_struct data_old;
+ data_old.effective = data_old.effective & 0xffffffffULL;
+ data_old.permitted = data_old.permitted & 0xffffffffULL;
+ data_old.inheritable = data_old.inheritable & 0xffffffffULL;
+ if (copy_to_user(dataptr, &data_old, sizeof data_old))
+ return -EFAULT;
+ } else
+ if (copy_to_user(dataptr, &data, sizeof data))
+ return -EFAULT;
+ }
return ret;
}
@@ -179,7 +190,8 @@ asmlinkage long sys_capset(cap_user_head
if (get_user(version, &header->version))
return -EFAULT;
- if (version != _LINUX_CAPABILITY_VERSION) {
+ if (version != _LINUX_CAPABILITY_VERSION
+ && version != _LINUX_CAPABILITY_OLD_VERSION) {
if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
return -EFAULT;
return -EINVAL;
@@ -191,10 +203,25 @@ asmlinkage long sys_capset(cap_user_head
if (pid && pid != current->pid && !capable(CAP_SETPCAP))
return -EPERM;
- if (copy_from_user(&effective, &data->effective, sizeof(effective)) ||
- copy_from_user(&inheritable, &data->inheritable, sizeof(inheritable)) ||
- copy_from_user(&permitted, &data->permitted, sizeof(permitted)))
- return -EFAULT;
+ if (version == _LINUX_CAPABILITY_OLD_VERSION) {
+ const cap_user_data_old_t data2 = (void *)data;
+ __u32 w;
+ /* Assume caller wants to keep all regular caps and clear
+ * all unknown additional caps. Is this right? */
+ if (copy_from_user(&w, &data2->effective, sizeof(w)))
+ return -EFAULT;
+ effective = (__u64)w | CAP_REGULAR_SET;
+ if (copy_from_user(&w, &data2->inheritable, sizeof(w)))
+ return -EFAULT;
+ inheritable = (__u64)w | CAP_REGULAR_SET;
+ if (copy_from_user(&w, &data2->permitted, sizeof(w)))
+ return -EFAULT;
+ permitted = (__u64)w | CAP_REGULAR_SET;
+ } else
+ if (copy_from_user(&effective, &data->effective, sizeof(effective)) ||
+ copy_from_user(&inheritable, &data->inheritable, sizeof(inheritable)) ||
+ copy_from_user(&permitted, &data->permitted, sizeof(permitted)))
+ return -EFAULT;
spin_lock(&task_capability_lock);
read_lock(&tasklist_lock);
@@ -237,7 +264,8 @@ out:
int __capable(struct task_struct *t, int cap)
{
if (security_capable(t, cap) == 0) {
- t->flags |= PF_SUPERPRIV;
+ if (!cap_raised(CAP_REGULAR_SET, cap))
+ t->flags |= PF_SUPERPRIV;
return 1;
}
return 0;
diff --git a/security/commoncap.c b/security/commoncap.c
index f50fc29..91dc53d 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -244,13 +244,19 @@ static inline void cap_emulate_setxuid (
int old_suid)
{
if ((old_ruid == 0 || old_euid == 0 || old_suid == 0) &&
- (current->uid != 0 && current->euid != 0 && current->suid != 0) &&
- !current->keep_capabilities) {
- cap_clear (current->cap_permitted);
- cap_clear (current->cap_effective);
+ (current->uid != 0 && current->euid != 0 && current->suid != 0)) {
+ if (!current->keep_capabilities) {
+ current->cap_permitted
+ = cap_intersect (current->cap_permitted,
+ CAP_REGULAR_SET);
+ current->cap_effective
+ = cap_intersect (current->cap_effective,
+ CAP_REGULAR_SET);
+ }
}
if (old_euid == 0 && current->euid != 0) {
- cap_clear (current->cap_effective);
+ current->cap_effective = cap_intersect (current->cap_effective,
+ CAP_REGULAR_SET);
}
if (old_euid != 0 && current->euid == 0) {
current->cap_effective = current->cap_permitted;
diff --git a/security/dummy.c b/security/dummy.c
index 58c6d39..572a15b 100644
--- a/security/dummy.c
+++ b/security/dummy.c
@@ -37,11 +37,11 @@ static int dummy_ptrace (struct task_str
static int dummy_capget (struct task_struct *target, kernel_cap_t * effective,
kernel_cap_t * inheritable, kernel_cap_t * permitted)
{
- *effective = *inheritable = *permitted = 0;
+ *effective = *inheritable = *permitted = CAP_REGULAR_SET;
if (!issecure(SECURE_NOROOT)) {
if (target->euid == 0) {
- *permitted |= (~0 & ~CAP_FS_MASK);
- *effective |= (~0 & ~CAP_TO_MASK(CAP_SETPCAP) & ~CAP_FS_MASK);
+ *permitted |= (CAP_FULL_SET & ~CAP_FS_MASK);
+ *effective |= (CAP_FULL_SET & ~CAP_TO_MASK(CAP_SETPCAP) & ~CAP_FS_MASK);
}
if (target->fsuid == 0) {
*permitted |= CAP_FS_MASK;
Make capabilities inheritable by default. The following remarks
apply:
* executables are assumed by default to have a full set of
"inheritable" (allowed) and "effective" capabilities,
* w.r.t. capabilities(7)-documented behavior, inheritance of the
effective bits is changed (use P(eff) rather than F(eff) in half
of the formula),
* also, inheritance of the inheritable set is based on the new
permitted set rather than on the old inheritable.
See <URL: http://www.madore.org/~david/linux/newcaps/ > for more
detailed explanations.
Signed-off-by: David A. Madore <[email protected]>
---
fs/exec.c | 4 +++
include/linux/binfmts.h | 1 +
kernel/capability.c | 2 +
security/commoncap.c | 69 ++++++++++++++++++++++++++++-------------------
4 files changed, 47 insertions(+), 29 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c
index 54135df..e4d0a2c 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -925,10 +925,13 @@ int prepare_binprm(struct linux_binprm *
bprm->e_uid = current->euid;
bprm->e_gid = current->egid;
+ bprm->is_suid = 0;
+ bprm->is_sgid = 0;
if(!(bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)) {
/* Set-uid? */
if (mode & S_ISUID) {
+ bprm->is_suid = 1;
current->personality &= ~PER_CLEAR_ON_SETID;
bprm->e_uid = inode->i_uid;
}
@@ -940,6 +943,7 @@ int prepare_binprm(struct linux_binprm *
* executable.
*/
if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
+ bprm->is_sgid = 1;
current->personality &= ~PER_CLEAR_ON_SETID;
bprm->e_gid = inode->i_gid;
}
diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h
index c1e82c5..c7fb183 100644
--- a/include/linux/binfmts.h
+++ b/include/linux/binfmts.h
@@ -29,6 +29,7 @@ struct linux_binprm{
struct file * file;
int e_uid, e_gid;
kernel_cap_t cap_inheritable, cap_permitted, cap_effective;
+ char is_suid, is_sgid;
void *security;
int argc, envc;
char * filename; /* Name of binary as seen by procps */
diff --git a/kernel/capability.c b/kernel/capability.c
index 32b2521..2bb802a 100644
--- a/kernel/capability.c
+++ b/kernel/capability.c
@@ -15,7 +15,7 @@ #include <linux/syscalls.h>
#include <asm/uaccess.h>
unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
-kernel_cap_t cap_bset = CAP_INIT_EFF_SET;
+kernel_cap_t cap_bset = CAP_INIT_INH_SET;
EXPORT_SYMBOL(securebits);
EXPORT_SYMBOL(cap_bset);
diff --git a/security/commoncap.c b/security/commoncap.c
index 91dc53d..3f90ae8 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -97,6 +97,8 @@ int cap_capset_check (struct task_struct
if (!cap_issubset (*effective, *permitted)) {
return -EPERM;
}
+ /* we allow Inheritable not to be a subset of Permitted:
+ * cap_capset_set will intersect them anyway */
return 0;
}
@@ -105,7 +107,7 @@ void cap_capset_set (struct task_struct
kernel_cap_t *inheritable, kernel_cap_t *permitted)
{
target->cap_effective = *effective;
- target->cap_inheritable = *inheritable;
+ target->cap_inheritable = cap_intersect (*permitted, *inheritable);
target->cap_permitted = *permitted;
}
@@ -114,25 +116,20 @@ int cap_bprm_set_security (struct linux_
/* Copied from fs/exec.c:prepare_binprm. */
/* We don't have VFS support for capabilities yet */
- cap_clear (bprm->cap_inheritable);
+ cap_set_full (bprm->cap_inheritable);
cap_clear (bprm->cap_permitted);
- cap_clear (bprm->cap_effective);
+ cap_set_full (bprm->cap_effective);
/* To support inheritance of root-permissions and suid-root
* executables under compatibility mode, we raise all three
* capability sets for the file.
- *
- * If only the real uid is 0, we only raise the inheritable
- * and permitted sets of the executable file.
*/
-
if (!issecure (SECURE_NOROOT)) {
- if (bprm->e_uid == 0 || current->uid == 0) {
+ if (bprm->is_suid && bprm->e_uid == 0) {
cap_set_full (bprm->cap_inheritable);
cap_set_full (bprm->cap_permitted);
- }
- if (bprm->e_uid == 0)
cap_set_full (bprm->cap_effective);
+ }
}
return 0;
}
@@ -140,13 +137,25 @@ int cap_bprm_set_security (struct linux_
void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe)
{
/* Derived from fs/exec.c:compute_creds. */
- kernel_cap_t new_permitted, working;
+ kernel_cap_t new_permitted, new_effective, working;
+ uid_t old_ruid, old_euid, old_suid;
+ /* P'(per) = (P(inh) & F(inh)) | (F(per) & bset) */
new_permitted = cap_intersect (bprm->cap_permitted, cap_bset);
working = cap_intersect (bprm->cap_inheritable,
current->cap_inheritable);
new_permitted = cap_combine (new_permitted, working);
+ /* P'(eff) = (P(inh) & P(eff) & F(inh)) | (F(per) & F(eff) & bset) */
+ new_effective = cap_intersect (bprm->cap_permitted, bprm->cap_effective);
+ new_effective = cap_intersect (new_effective, cap_bset);
+ working = cap_intersect (bprm->cap_inheritable,
+ current->cap_effective);
+ working = cap_intersect (working, current->cap_inheritable);
+ new_effective = cap_combine (new_effective, working);
+
+ /* P'(inh) = P'(per) */
+
if (bprm->e_uid != current->uid || bprm->e_gid != current->gid ||
!cap_issubset (new_permitted, current->cap_permitted)) {
current->mm->dumpable = suid_dumpable;
@@ -159,36 +168,37 @@ void cap_bprm_apply_creds (struct linux_
if (!capable (CAP_SETPCAP)) {
new_permitted = cap_intersect (new_permitted,
current->cap_permitted);
+ new_effective = cap_intersect (new_permitted,
+ new_effective);
}
}
}
+ old_ruid = current->uid;
+ old_euid = current->euid;
+ old_suid = current->suid;
current->suid = current->euid = current->fsuid = bprm->e_uid;
current->sgid = current->egid = current->fsgid = bprm->e_gid;
- /* For init, we want to retain the capabilities set
- * in the init_task struct. Thus we skip the usual
- * capability rules */
- if (current->pid != 1) {
- current->cap_permitted = new_permitted;
- current->cap_effective =
- cap_intersect (new_permitted, bprm->cap_effective);
- }
-
- /* AUD: Audit candidate if current->cap_effective is set */
+ current->cap_permitted = new_permitted;
+ current->cap_effective = new_effective;
+ current->cap_inheritable = new_permitted;
current->keep_capabilities = 0;
+ /* Make sure we drop capabilities if required by suid. */
+ cap_task_post_setuid (old_ruid, old_euid, old_suid, LSM_SETID_RES);
+
+ /* AUD: Audit candidate if current->cap_effective is set */
}
int cap_bprm_secureexec (struct linux_binprm *bprm)
{
/* If/when this module is enhanced to incorporate capability
bits on files, the test below should be extended to also perform a
- test between the old and new capability sets. For now,
- it simply preserves the legacy decision algorithm used by
- the old userland. */
- return (current->euid != current->uid ||
- current->egid != current->gid);
+ test between the old and new capability sets. */
+ return ((bprm->is_suid || bprm->is_sgid)
+ && !cap_issubset (bprm->cap_permitted,
+ current->cap_permitted));
}
int cap_inode_setxattr(struct dentry *dentry, char *name, void *value,
@@ -253,12 +263,15 @@ static inline void cap_emulate_setxuid (
= cap_intersect (current->cap_effective,
CAP_REGULAR_SET);
}
+ current->cap_inheritable
+ = cap_intersect (current->cap_inheritable,
+ CAP_REGULAR_SET);
}
- if (old_euid == 0 && current->euid != 0) {
+ if (old_euid == 0 && current->euid != 0 && !current->keep_capabilities) {
current->cap_effective = cap_intersect (current->cap_effective,
CAP_REGULAR_SET);
}
- if (old_euid != 0 && current->euid == 0) {
+ if (old_euid != 0 && current->euid == 0 && !current->keep_capabilities) {
current->cap_effective = current->cap_permitted;
}
}
Introduce six new "regular" (=on-by-default) capabilities:
* CAP_REG_FORK, CAP_REG_OPEN, CAP_REG_EXEC allow access to the
fork(), open() and exec() syscalls,
* CAP_REG_SXID allows privilege gain on suid/sgid exec,
* CAP_REG_WRITE controls any write-access to the filesystem,
* CAP_REG_PTRACE allows ptrace().
See <URL: http://www.madore.org/~david/linux/newcaps/ > for more
detailed explanations.
Signed-off-by: David A. Madore <[email protected]>
---
fs/exec.c | 7 +++++--
fs/namei.c | 2 +-
fs/open.c | 26 ++++++++++++++++++++------
fs/xattr.c | 3 ++-
include/linux/capability.h | 23 +++++++++++++++++++++++
kernel/fork.c | 2 ++
kernel/ptrace.c | 2 ++
7 files changed, 55 insertions(+), 10 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c
index e4d0a2c..1cb5e34 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -930,7 +930,7 @@ int prepare_binprm(struct linux_binprm *
if(!(bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)) {
/* Set-uid? */
- if (mode & S_ISUID) {
+ if (mode & S_ISUID && capable(CAP_REG_SXID)) {
bprm->is_suid = 1;
current->personality &= ~PER_CLEAR_ON_SETID;
bprm->e_uid = inode->i_uid;
@@ -942,7 +942,8 @@ int prepare_binprm(struct linux_binprm *
* is a candidate for mandatory locking, not a setgid
* executable.
*/
- if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
+ if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)
+ && capable(CAP_REG_SXID)) {
bprm->is_sgid = 1;
current->personality &= ~PER_CLEAR_ON_SETID;
bprm->e_gid = inode->i_gid;
@@ -1137,6 +1138,8 @@ int do_execve(char * filename,
int retval;
int i;
+ if (!capable(CAP_REG_EXEC))
+ return -EPERM;
retval = -ENOMEM;
bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
if (!bprm)
diff --git a/fs/namei.c b/fs/namei.c
index 432d6bc..69a3bae 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -242,7 +242,7 @@ int permission(struct inode *inode, int
/*
* Nobody gets write access to an immutable file.
*/
- if (IS_IMMUTABLE(inode))
+ if (IS_IMMUTABLE(inode) || !capable(CAP_REG_WRITE))
return -EACCES;
}
diff --git a/fs/open.c b/fs/open.c
index e58a525..77a12ba 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -253,7 +253,7 @@ static long do_sys_truncate(const char _
goto dput_and_out;
error = -EPERM;
- if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
+ if (IS_IMMUTABLE(inode) || IS_APPEND(inode) || !capable(CAP_REG_WRITE))
goto dput_and_out;
/*
@@ -382,6 +382,10 @@ asmlinkage long sys_utime(char __user *
if (IS_RDONLY(inode))
goto dput_and_out;
+ error = -EPERM;
+ if (!capable(CAP_REG_WRITE))
+ goto dput_and_out;
+
/* Don't worry, the checks are done in inode_change_ok() */
newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
if (times) {
@@ -439,6 +443,10 @@ long do_utimes(int dfd, char __user *fil
if (IS_RDONLY(inode))
goto dput_and_out;
+ error = -EPERM;
+ if (!capable(CAP_REG_WRITE))
+ goto dput_and_out;
+
/* Don't worry, the checks are done in inode_change_ok() */
newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
if (times) {
@@ -640,7 +648,7 @@ asmlinkage long sys_fchmod(unsigned int
if (IS_RDONLY(inode))
goto out_putf;
err = -EPERM;
- if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
+ if (IS_IMMUTABLE(inode) || IS_APPEND(inode) || !capable(CAP_REG_WRITE))
goto out_putf;
mutex_lock(&inode->i_mutex);
if (mode == (mode_t) -1)
@@ -674,7 +682,7 @@ asmlinkage long sys_fchmodat(int dfd, co
goto dput_and_out;
error = -EPERM;
- if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
+ if (IS_IMMUTABLE(inode) || IS_APPEND(inode) || !capable(CAP_REG_WRITE))
goto dput_and_out;
mutex_lock(&inode->i_mutex);
@@ -711,7 +719,7 @@ static int chown_common(struct dentry *
if (IS_RDONLY(inode))
goto out;
error = -EPERM;
- if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
+ if (IS_IMMUTABLE(inode) || IS_APPEND(inode) || !capable(CAP_REG_WRITE))
goto out;
newattrs.ia_valid = ATTR_CTIME;
if (user != (uid_t) -1) {
@@ -1105,7 +1113,10 @@ asmlinkage long sys_open(const char __us
if (force_o_largefile())
flags |= O_LARGEFILE;
- ret = do_sys_open(AT_FDCWD, filename, flags, mode);
+ if (capable(CAP_REG_OPEN))
+ ret = do_sys_open(AT_FDCWD, filename, flags, mode);
+ else
+ ret = -EPERM;
/* avoid REGPARM breakage on x86: */
prevent_tail_call(ret);
return ret;
@@ -1120,7 +1131,10 @@ asmlinkage long sys_openat(int dfd, cons
if (force_o_largefile())
flags |= O_LARGEFILE;
- ret = do_sys_open(dfd, filename, flags, mode);
+ if (capable(CAP_REG_OPEN))
+ ret = do_sys_open(dfd, filename, flags, mode);
+ else
+ ret = -EPERM;
/* avoid REGPARM breakage on x86: */
prevent_tail_call(ret);
return ret;
diff --git a/fs/xattr.c b/fs/xattr.c
index c32f15b..33b70ce 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -35,7 +35,8 @@ xattr_permission(struct inode *inode, co
if (mask & MAY_WRITE) {
if (IS_RDONLY(inode))
return -EROFS;
- if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
+ if (IS_IMMUTABLE(inode) || IS_APPEND(inode)
+ || !capable(CAP_REG_WRITE))
return -EPERM;
}
diff --git a/include/linux/capability.h b/include/linux/capability.h
index aa00b60..efc268e 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -295,6 +295,29 @@ #define CAP_AUDIT_WRITE 29
#define CAP_AUDIT_CONTROL 30
+
+/**
+ ** Regular capabilities (normally possessed by all processes).
+ **/
+
+/* Can fork() */
+#define CAP_REG_FORK 32
+
+/* Can open() */
+#define CAP_REG_OPEN 33
+
+/* Can exec() */
+#define CAP_REG_EXEC 34
+
+/* Might gain permissions on exec() */
+#define CAP_REG_SXID 35
+
+/* Perform write access to the filesystem */
+#define CAP_REG_WRITE 36
+
+/* Can use ptrace() */
+#define CAP_REG_PTRACE 37
+
#ifdef __KERNEL__
/*
* Bounding set
diff --git a/kernel/fork.c b/kernel/fork.c
index f9b014e..20f559f 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1347,6 +1347,8 @@ long do_fork(unsigned long clone_flags,
struct pid *pid = alloc_pid();
long nr;
+ if (!capable(CAP_REG_FORK))
+ return -EPERM;
if (!pid)
return -EAGAIN;
nr = pid->nr;
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 9a111f7..093307d 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -132,6 +132,8 @@ static int may_attach(struct task_struct
/* Don't let security modules deny introspection */
if (task == current)
return 0;
+ if (!capable(CAP_REG_PTRACE))
+ return -EPERM;
if (((current->uid != task->euid) ||
(current->uid != task->suid) ||
(current->uid != task->uid) ||
Add filesystem support for capabilities. This is controlled by the
security.capability extended attribute.
Originally a merge from <URL: http://lkml.org/lkml/2006/9/6/229 >.
Notes:
* mounting nosuid deactivates the permitted ("forced") set of
capabilities on executables, similarly if no CAP_REG_SXID.
See <URL: http://www.madore.org/~david/linux/newcaps/ > for more
detailed explanations.
Signed-off-by: David A. Madore <[email protected]>
---
include/linux/capability.h | 3 +
include/linux/security.h | 10 ++-
security/Kconfig | 10 +++
security/capability.c | 4 +
security/commoncap.c | 155 ++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 178 insertions(+), 4 deletions(-)
diff --git a/include/linux/capability.h b/include/linux/capability.h
index efc268e..428ccc5 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -295,6 +295,9 @@ #define CAP_AUDIT_WRITE 29
#define CAP_AUDIT_CONTROL 30
+/* Number of low (=system, =additional) caps */
+#define CAP_NUMCAPS_SYS 30
+
/**
** Regular capabilities (normally possessed by all processes).
diff --git a/include/linux/security.h b/include/linux/security.h
index 6bc2aad..265ab00 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -51,6 +51,10 @@ extern int cap_inode_setxattr(struct den
extern int cap_inode_removexattr(struct dentry *dentry, char *name);
extern int cap_task_post_setuid (uid_t old_ruid, uid_t old_euid, uid_t old_suid, int flags);
extern void cap_task_reparent_to_init (struct task_struct *p);
+extern int cap_task_kill(struct task_struct *p, struct siginfo *info, int sig, u32 secid);
+extern int cap_task_setscheduler (struct task_struct *p, int policy, struct sched_param *lp);
+extern int cap_task_setioprio (struct task_struct *p, int ioprio);
+extern int cap_task_setnice (struct task_struct *p, int nice);
extern int cap_syslog (int type);
extern int cap_vm_enough_memory (long pages);
@@ -2544,12 +2548,12 @@ static inline int security_task_setgroup
static inline int security_task_setnice (struct task_struct *p, int nice)
{
- return 0;
+ return cap_task_setnice(p, nice);
}
static inline int security_task_setioprio (struct task_struct *p, int ioprio)
{
- return 0;
+ return cap_task_setioprio(p, ioprio);
}
static inline int security_task_getioprio (struct task_struct *p)
@@ -2584,7 +2588,7 @@ static inline int security_task_kill (st
struct siginfo *info, int sig,
u32 secid)
{
- return 0;
+ return cap_task_kill(p, info, sig, secid);
}
static inline int security_task_wait (struct task_struct *p)
diff --git a/security/Kconfig b/security/Kconfig
index 67785df..ce2bac7 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -80,6 +80,16 @@ config SECURITY_CAPABILITIES
This enables the "default" Linux capabilities functionality.
If you are unsure how to answer this question, answer Y.
+config SECURITY_FS_CAPABILITIES
+ bool "Filesystem Capabilities"
+ depends on SECURITY_CAPABILITIES
+ default n
+ help
+ This enables filesystem capabilities, allowing you to give
+ binaries a subset of root's powers without using setuid 0.
+
+ If in doubt, answer N.
+
config SECURITY_ROOTPLUG
tristate "Root Plug Support"
depends on USB && SECURITY
diff --git a/security/capability.c b/security/capability.c
index b868e7e..14cb592 100644
--- a/security/capability.c
+++ b/security/capability.c
@@ -40,6 +40,10 @@ static struct security_operations capabi
.inode_setxattr = cap_inode_setxattr,
.inode_removexattr = cap_inode_removexattr,
+ .task_kill = cap_task_kill,
+ .task_setscheduler = cap_task_setscheduler,
+ .task_setioprio = cap_task_setioprio,
+ .task_setnice = cap_task_setnice,
.task_post_setuid = cap_task_post_setuid,
.task_reparent_to_init = cap_task_reparent_to_init,
diff --git a/security/commoncap.c b/security/commoncap.c
index 3f90ae8..2c51c8d 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -23,6 +23,7 @@ #include <linux/netlink.h>
#include <linux/ptrace.h>
#include <linux/xattr.h>
#include <linux/hugetlb.h>
+#include <linux/mount.h>
int cap_netlink_send(struct sock *sk, struct sk_buff *skb)
{
@@ -111,11 +112,55 @@ void cap_capset_set (struct task_struct
target->cap_permitted = *permitted;
}
+#define XATTR_CAPS_SUFFIX "capability"
+#define XATTR_NAME_CAPS XATTR_SECURITY_PREFIX XATTR_CAPS_SUFFIX
+struct vfs_cap_data_struct {
+ __u32 version;
+ __u32 effective;
+ __u32 permitted;
+ __u32 inheritable;
+};
+
+static inline void convert_to_le(struct vfs_cap_data_struct *cap)
+{
+ cap->version = le32_to_cpu(cap->version);
+ cap->effective = le32_to_cpu(cap->effective);
+ cap->permitted = le32_to_cpu(cap->permitted);
+ cap->inheritable = le32_to_cpu(cap->inheritable);
+}
+
+static int check_cap_sanity(struct vfs_cap_data_struct *cap)
+{
+ int i;
+
+ if (cap->version != _LINUX_CAPABILITY_OLD_VERSION)
+ return -EPERM;
+
+ for (i=CAP_NUMCAPS_SYS; i<sizeof(cap->effective); i++) {
+ if (cap->effective & CAP_TO_MASK(i))
+ return -EPERM;
+ }
+ for (i=CAP_NUMCAPS_SYS; i<sizeof(cap->permitted); i++) {
+ if (cap->permitted & CAP_TO_MASK(i))
+ return -EPERM;
+ }
+ for (i=CAP_NUMCAPS_SYS; i<sizeof(cap->inheritable); i++) {
+ if (cap->inheritable & CAP_TO_MASK(i))
+ return -EPERM;
+ }
+
+ return 0;
+}
+
int cap_bprm_set_security (struct linux_binprm *bprm)
{
+ struct dentry *dentry;
+ ssize_t rc;
+ struct vfs_cap_data_struct cap_struct;
+ struct inode *inode;
+
/* Copied from fs/exec.c:prepare_binprm. */
- /* We don't have VFS support for capabilities yet */
cap_set_full (bprm->cap_inheritable);
cap_clear (bprm->cap_permitted);
cap_set_full (bprm->cap_effective);
@@ -131,6 +176,54 @@ int cap_bprm_set_security (struct linux_
cap_set_full (bprm->cap_effective);
}
}
+
+#ifdef CONFIG_SECURITY_FS_CAPABILITIES
+ /* Locate any VFS capabilities: */
+
+ dentry = dget(bprm->file->f_dentry);
+ inode = dentry->d_inode;
+ if (!inode->i_op || !inode->i_op->getxattr) {
+ dput(dentry);
+ return 0;
+ }
+
+ rc = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, &cap_struct,
+ sizeof(cap_struct));
+ dput(dentry);
+
+ if (rc == -ENODATA)
+ return 0;
+
+ if (rc < 0) {
+ printk(KERN_NOTICE "%s: Error (%ld) getting xattr\n",
+ __FUNCTION__, (long int)rc);
+ return rc;
+ }
+
+ if (rc != sizeof(cap_struct)) {
+ printk(KERN_NOTICE "%s: got wrong size for getxattr (%ld)\n",
+ __FUNCTION__, (long int)rc);
+ return -EPERM;
+ }
+
+ convert_to_le(&cap_struct);
+ if (check_cap_sanity(&cap_struct))
+ return -EPERM;
+
+ bprm->cap_effective = cap_combine (cap_intersect (bprm->cap_effective,
+ CAP_REGULAR_SET),
+ to_cap_t(cap_struct.effective));
+ bprm->cap_permitted = cap_combine (cap_intersect (bprm->cap_permitted,
+ CAP_REGULAR_SET),
+ to_cap_t(cap_struct.permitted));
+ if (!(bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)
+ || !capable(CAP_REG_SXID)) /* Don't allow to gain privileges! */
+ cap_clear (bprm->cap_permitted);
+ bprm->cap_inheritable = cap_combine (cap_intersect (bprm->cap_inheritable,
+ CAP_REGULAR_SET),
+ to_cap_t(cap_struct.inheritable));
+
+#endif
return 0;
}
@@ -319,6 +412,62 @@ int cap_task_post_setuid (uid_t old_ruid
return 0;
}
+/*
+ * 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 inline int cap_safe_nice(struct task_struct *p)
+{
+ if (!cap_issubset(p->cap_permitted, current->cap_permitted) &&
+ !__capable(current, CAP_SYS_NICE))
+ return -EPERM;
+ return 0;
+}
+
+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)
+{
+ return cap_safe_nice(p);
+}
+
+int cap_task_setnice (struct task_struct *p, int nice)
+{
+ return cap_safe_nice(p);
+}
+
+int cap_task_kill(struct task_struct *p, struct siginfo *info,
+ int sig, u32 secid)
+{
+ if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info)))
+ return 0;
+
+ if (secid)
+ /*
+ * Signal sent as a particular user.
+ * Capabilities are ignored. May be wrong, but it's the
+ * only thing we can do at the moment.
+ * Used only by usb drivers?
+ */
+ return 0;
+ if (capable(CAP_KILL))
+ return 0;
+ if (cap_issubset(p->cap_permitted, current->cap_permitted))
+ return 0;
+
+ return -EPERM;
+}
+
void cap_task_reparent_to_init (struct task_struct *p)
{
p->cap_effective = CAP_INIT_EFF_SET;
@@ -356,6 +505,10 @@ EXPORT_SYMBOL(cap_bprm_secureexec);
EXPORT_SYMBOL(cap_inode_setxattr);
EXPORT_SYMBOL(cap_inode_removexattr);
EXPORT_SYMBOL(cap_task_post_setuid);
+EXPORT_SYMBOL(cap_task_kill);
+EXPORT_SYMBOL(cap_task_setscheduler);
+EXPORT_SYMBOL(cap_task_setioprio);
+EXPORT_SYMBOL(cap_task_setnice);
EXPORT_SYMBOL(cap_task_reparent_to_init);
EXPORT_SYMBOL(cap_syslog);
EXPORT_SYMBOL(cap_vm_enough_memory);