Turns out execve looks at it to store binary name, but in order to
trigger the problem one has to be trying to exec '/'. As is the value
would be left uninitialized (or rather set to -1 on debug kernels).
Fixes: 56244d35741a62e7 ("vfs: hoist degenerate path lookups out of the
loop")
This avoids spurious drop offs as EMPTY is passed regardless of the
actual path name.
Pushign the work inside the lookup instead of just ignorign the flag
allows avoid checking for empty pathname for all other lookups.
On kernels compiled with 'options TSLOG', record for each process ID:
* The timestamp of the fork() which creates it and the parent
process ID,
* The first path passed to execve(), if any,
* The first path resolved by namei, if any, and
* The timestamp of the exit() which terminates the process.
Expose this information via a new sysctl, debug.tslog_user.
On kernels lacking 'options TSLOG' (the default), no information is
recorded and the sysctl does not exist.
Note that recording namei is needed in order to obtain the names of
rc.d scripts being launched, as the rc system sources them in a
subshell rather than execing the scripts.
With this commit it is now possible to generate flamecharts of the
entire boot process from the start of the loader to the end of
/etc/rc. The code needed to perform this processing is currently
found in github: https://github.com/cperciva/freebsd-boot-profiling
Reviewed by: mhorne
Sponsored by: https://www.patreon.com/cperciva
Differential Revision: https://reviews.freebsd.org/D32493
Set NIRES_EMPTYPATH earlies, to have use of EMPTYPATH recorded even if
we are going to return error. When namei_setup() refused to accept dirfd,
which is not of the vnode type, and indicated by ENOTDIR error return,
fall back to kern_fstat(dirfd).
Reported by: dchagin
Reviewed by: markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D31530
by only keeping hold count on the vnode, instead of the use count.
Reviewed by: markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D29323
It is currently allowed to fchownat(2), fchmodat(2), fchflagsat(2),
utimensat(2), fstatat(2), and linkat(2).
For linkat(2), PRIV_VFS_FHOPEN privilege is required to exercise the flag.
It allows to link any open file.
Requested by: trasz
Tested by: pho, trasz
Reviewed by: markj
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D29111
Some filesystems assume that they can copy a name component, with length
bounded by NAME_MAX, into a dirent buffer of size MAXNAMLEN. These
constants have the same value; add a compile-time assertion to that
effect.
Reported by: Alexey Kulaev <alex.qart@gmail.com>
Reviewed by: kib
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D29431
Tracker should contain exactly the path from the starting directory to
the current lookup point. Otherwise we might not detect some cases of
dotdot escape. Consequently, if we are walking up the tree by dotdot
lookup, we must remove an entries below the walked directory.
Reviewed by: markj
Tested by: arichardson, pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D28907
with the reasoning that the flags did not worked properly, and were not
shipped in a release.
O_RESOLVE_BENEATH is kept as useful.
Reviewed by: markj
Tested by: arichardson, pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D28907
Both FreeBSD and Linux mkdir -p walk the tree up ignoring any EEXIST on
the way and both are used a lot when building respective kernels.
This poses a problem as spurious locking avoidably interferes with
concurrent operations like getdirentries on affected directories.
Work around the problem by adding FAILIFEXISTS flag. In case of lockless
lookup this manages to avoid any work to begin with, there is no speed
up for the locked case but perhaps this can be augmented later on.
For simplicity the only supported semantics are as used by mkdir.
Reviewed by: kib (previous version)
Differential Revision: https://reviews.freebsd.org/D27789
struct nameidata mixes caller arguments, internal state and output, which
can be quite error prone.
Recent addition of valdiating ni_resflags uncovered a caller which could
repeatedly call namei, effectively operating on partially populated state.
Add bare minimium validation this does not happen. The real fix would
decouple aforementioned state.
Reported by: pho
Tested by: pho (different variant)
Specifically, if lookup() returned any error and the topping directory
was not latched, which means that (non-existent) path did not returned
to the topping location, give ENOTCAPABLE a priority over the lookup()
error.
PR: 249960
Reviewed by: emaste, ngie
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D26695
It is like O_BENEATH, but disables to walk out of the subtree rooted
in the starting directory. O_BENEATH does not care if path walks out
if it returned.
Requested by: Dan Gohman <dev@sunfishcode.online>
PR: 248335
Reviewed by: markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D25886
Do not care if path walks out of the topping directory if it returns back.
Requested and reviewed by: markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D25886
not unconditionally on any dotdot component.
Reviewed by: markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D25886
