Author: jh
Date: Mon Aug 30 16:30:18 2010
New Revision: 212002
URL: http://svn.freebsd.org/changeset/base/212002
Log:
execve(2) has a special check for file permissions: a file must have at
least one execute bit set, otherwise execve(2) will return EACCES even
for an user with PRIV_VFS_EXEC privilege.
Add the check also to vaccess(9), vaccess_acl_nfs4(9) and
vaccess_acl_posix1e(9). This makes access(2) to better agree with
execve(2). Because ZFS doesn't use vaccess(9) for VEXEC, add the check
to zfs_freebsd_access() too. There may be other file systems which are
not using vaccess*() functions and need to be handled separately.
PR: kern/125009
Reviewed by: bde, trasz
Approved by: pjd (ZFS part)
Modified:
head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
head/sys/kern/kern_exec.c
head/sys/kern/subr_acl_nfs4.c
head/sys/kern/subr_acl_posix1e.c
head/sys/kern/vfs_subr.c
Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c Mon Aug
30 15:06:55 2010 (r212001)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c Mon Aug
30 16:30:18 2010 (r212002)
@@ -4247,6 +4247,9 @@ zfs_freebsd_access(ap)
struct thread *a_td;
} */ *ap;
{
+ vnode_t *vp = ap->a_vp;
+ znode_t *zp = VTOZ(vp);
+ znode_phys_t *zphys = zp->z_phys;
accmode_t accmode;
int error = 0;
@@ -4263,16 +4266,20 @@ zfs_freebsd_access(ap)
if (error == 0) {
accmode = ap->a_accmode & ~(VREAD|VWRITE|VEXEC|VAPPEND);
if (accmode != 0) {
- vnode_t *vp = ap->a_vp;
- znode_t *zp = VTOZ(vp);
- znode_phys_t *zphys = zp->z_phys;
-
error = vaccess(vp->v_type, zphys->zp_mode,
zphys->zp_uid, zphys->zp_gid, accmode, ap->a_cred,
NULL);
}
}
+ /*
+ * For VEXEC, ensure that at least one execute bit is set for
+ * non-directories.
+ */
+ if (error == 0 && (ap->a_accmode & VEXEC) != 0 && vp->v_type != VDIR &&
+ (zphys->zp_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0)
+ error = EACCES;
+
return (error);
}
Modified: head/sys/kern/kern_exec.c
==============================================================================
--- head/sys/kern/kern_exec.c Mon Aug 30 15:06:55 2010 (r212001)
+++ head/sys/kern/kern_exec.c Mon Aug 30 16:30:18 2010 (r212002)
@@ -1363,17 +1363,17 @@ exec_check_permissions(imgp)
if (error)
return (error);
#endif
-
+
/*
- * 1) Check if file execution is disabled for the filesystem that this
- * file resides on.
- * 2) Insure that at least one execute bit is on - otherwise root
- * will always succeed, and we don't want to happen unless the
- * file really is executable.
- * 3) Insure that the file is a regular file.
+ * 1) Check if file execution is disabled for the filesystem that
+ * this file resides on.
+ * 2) Ensure that at least one execute bit is on. Otherwise, a
+ * privileged user will always succeed, and we don't want this
+ * to happen unless the file really is executable.
+ * 3) Ensure that the file is a regular file.
*/
if ((vp->v_mount->mnt_flag & MNT_NOEXEC) ||
- ((attr->va_mode & 0111) == 0) ||
+ (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 ||
(attr->va_type != VREG))
return (EACCES);
Modified: head/sys/kern/subr_acl_nfs4.c
==============================================================================
--- head/sys/kern/subr_acl_nfs4.c Mon Aug 30 15:06:55 2010
(r212001)
+++ head/sys/kern/subr_acl_nfs4.c Mon Aug 30 16:30:18 2010
(r212002)
@@ -162,6 +162,7 @@ vaccess_acl_nfs4(enum vtype type, uid_t
accmode_t priv_granted = 0;
int denied, explicitly_denied, access_mask, is_directory,
must_be_owner = 0;
+ mode_t file_mode;
KASSERT((accmode & ~(VEXEC | VWRITE | VREAD | VADMIN | VAPPEND |
VEXPLICIT_DENY | VREAD_NAMED_ATTRS | VWRITE_NAMED_ATTRS |
@@ -216,6 +217,17 @@ vaccess_acl_nfs4(enum vtype type, uid_t
denied = EPERM;
}
+ /*
+ * For VEXEC, ensure that at least one execute bit is set for
+ * non-directories. We have to check the mode here to stay
+ * consistent with execve(2). See the test in
+ * exec_check_permissions().
+ */
+ acl_nfs4_sync_mode_from_acl(&file_mode, aclp);
+ if (!denied && !is_directory && (accmode & VEXEC) &&
+ (file_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0)
+ denied = EACCES;
+
if (!denied)
return (0);
@@ -236,8 +248,14 @@ vaccess_acl_nfs4(enum vtype type, uid_t
PRIV_VFS_LOOKUP, 0))
priv_granted |= VEXEC;
} else {
- if ((accmode & VEXEC) && !priv_check_cred(cred,
- PRIV_VFS_EXEC, 0))
+ /*
+ * Ensure that at least one execute bit is on. Otherwise,
+ * a privileged user will always succeed, and we don't want
+ * this to happen unless the file really is executable.
+ */
+ if ((accmode & VEXEC) && (file_mode &
+ (S_IXUSR | S_IXGRP | S_IXOTH)) != 0 &&
+ !priv_check_cred(cred, PRIV_VFS_EXEC, 0))
priv_granted |= VEXEC;
}
Modified: head/sys/kern/subr_acl_posix1e.c
==============================================================================
--- head/sys/kern/subr_acl_posix1e.c Mon Aug 30 15:06:55 2010
(r212001)
+++ head/sys/kern/subr_acl_posix1e.c Mon Aug 30 16:30:18 2010
(r212002)
@@ -90,8 +90,14 @@ vaccess_acl_posix1e(enum vtype type, uid
PRIV_VFS_LOOKUP, 0))
priv_granted |= VEXEC;
} else {
- if ((accmode & VEXEC) && !priv_check_cred(cred,
- PRIV_VFS_EXEC, 0))
+ /*
+ * Ensure that at least one execute bit is on. Otherwise,
+ * a privileged user will always succeed, and we don't want
+ * this to happen unless the file really is executable.
+ */
+ if ((accmode & VEXEC) && (acl_posix1e_acl_to_mode(acl) &
+ (S_IXUSR | S_IXGRP | S_IXOTH)) != 0 &&
+ !priv_check_cred(cred, PRIV_VFS_EXEC, 0))
priv_granted |= VEXEC;
}
Modified: head/sys/kern/vfs_subr.c
==============================================================================
--- head/sys/kern/vfs_subr.c Mon Aug 30 15:06:55 2010 (r212001)
+++ head/sys/kern/vfs_subr.c Mon Aug 30 16:30:18 2010 (r212002)
@@ -3619,7 +3619,13 @@ privcheck:
!priv_check_cred(cred, PRIV_VFS_LOOKUP, 0))
priv_granted |= VEXEC;
} else {
+ /*
+ * Ensure that at least one execute bit is on. Otherwise,
+ * a privileged user will always succeed, and we don't want
+ * this to happen unless the file really is executable.
+ */
if ((accmode & VEXEC) && ((dac_granted & VEXEC) == 0) &&
+ (file_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) != 0 &&
!priv_check_cred(cred, PRIV_VFS_EXEC, 0))
priv_granted |= VEXEC;
}
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