MAP_FIXED has been widely used for a very long time, yet the man
page still claims that "the use of this option is discouraged".
The documentation assumes that "less portable" == "must be discouraged".
Instead of discouraging something that is so useful and widely used,
change the documentation to explain its limitations better.
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Note explicitly that SECBIT_NO_SETUID_FIXUP is relevant for
the permitted, effective, and ambient capability sets.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
It makes no sense to describe this flag in two different
manual pages, so consolidate the description to one page.
Furthermore, the following statement that was in the prctl(2)
page is not correct:
A thread's effective capability set is always cleared
when such a credential change is made, regardless of
the setting of the "keep capabilities" flag.
The effective set is not cleared if, for example, the
credential sets were [ruid != 0, euid != 0, suid == 0]
and suid is switched to zero while the "keep capabilities"
flag is set.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
See cap_emulate_setxuid():
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);
}
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Compile warning with glibc 2.25:
warning: In the GNU C Library, "makedev" is defined by
<sys/sysmacros.h>. For historical compatibility, it is
currently defined by <sys/types.h> as well, but we plan to
remove this soon. To use "makedev", include <sys/sysmacros.h>
directly. If you did not intend to use a system-defined macro
"makedev", you should undefine it after including
<sys/types.h>.
Background: glibc commit dbab6577c6684c62bd2521c1c29dc25c3cac966f
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
As hinted in the kernel source, MAX_HANDLE_SZ is a hint
rather than a promise:
/* limit the handle size to NFSv4 handle size now */
#define MAX_HANDLE_SZ 128
Note the "now" (probably should be "for now").
So change the description to make this clear.
Reported-by: Lennart Poettering <lennart@poettering.net>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
QingFeng Hao