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Author SHA1 Message Date
Carlos O'Donell dbb01cbbdb pthread_setcancelstate.3, pthreads.7, signal-safety.7: Describe issues with cancellation points in signal handlers 
In a recent conversation with Mathieu Desnoyers I was reminded
that we haven't written up anything about how deferred
cancellation and asynchronous signal handlers interact. Mathieu
ran into some of this behaviour and I promised to improve the
documentation in this area to point out the potential pitfall.

Thoughts?

8< --- 8< --- 8<
In pthread_setcancelstate.3, pthreads.7, and signal-safety.7 we
describe that if you have an asynchronous signal nesting over a
deferred cancellation region that any cancellation point in the
signal handler may trigger a cancellation that will behave
as-if it was an asynchronous cancellation. This asynchronous
cancellation may have unexpected effects on the consistency of
the application. Therefore care should be taken with asynchronous
signals and deferred cancellation.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-10-05 14:54:02 +03:00
Michael Kerrisk 27f942adbc sched_setparam.2, pthread_mutexattr_init.3, pthread_mutexattr_setrobust.3, pthread_mutex_consistent.3, strtol.3, sched.7, uts_namespaces.7: SEE ALSO: correct list order 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-09-27 14:18:46 +02:00
Michael Kerrisk c148832982 veth.4, persistent-keyring.7, process-keyring.7, session-keyring.7, thread-keyring.7, user-keyring.7, user-session-keyring.7: srcfix 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-09-27 14:18:46 +02:00
Michael Kerrisk 43d438e29b mount_namespaces.7: SEE ALSO: refer to example in pivot_root(2) 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-09-23 13:11:19 +02:00
Michael Kerrisk cc245e5bf8 operator.7: Prefix and postfix ++/-- have different precedences 
Harbison and Steele also agree on this.

Reported-by: Rick Stanley <rstanley@rsiny.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-09-22 22:58:45 +02:00
Michael Kerrisk 4dfeb670df man-pages.7: Relocate and enhance the text on semantic newlines 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-09-13 15:39:04 +02:00
Michael Kerrisk 724ca69c82 man-pages.7: Paragraphs should not be separated by blank lines 
Reported-by: Paul Wise <pabs3@bonedaddy.net>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-09-13 15:26:13 +02:00
Jakub Wilk 8f397fb4a1 fanotify.7: tfix 
Signed-off-by: Jakub Wilk <jwilk@jwilk.net>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-09-10 12:45:14 +02:00
Michael Kerrisk 96f49e54da signal.7: tfix 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-08-28 11:58:00 +02:00
Eric Biggers 15f2303db3 cgroups.7: tfix 
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-08-26 23:14:49 +02:00
Marko Myllynen d6094c8a3b capabilities.7: tfix 
Hi Michael, it's been a while but few simple patches today..

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-08-26 23:14:49 +02:00
Marko Myllynen 8a6c2ad5a8 user_namespaces.7: tfix 
This and the previous were the only ones grep found.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-08-26 23:14:49 +02:00
Michael Kerrisk 252bba449e uts_namespaces.7: SEE ALSO: add gethostname(2), getdomainname(2), uname(2) 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-08-26 23:14:49 +02:00
Michael Kerrisk 30e022e516 namespaces.7: Remove content migrated to uts_namespaces(7) 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-08-26 23:14:49 +02:00
Michael Kerrisk 57829a0e87 uts_namespaces.7: New page with content migrated from namespaces(7) 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-08-26 23:14:49 +02:00
Michael Kerrisk ab1dc74922 mq_overview.7: wfix 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-08-26 23:14:49 +02:00
Michael Kerrisk c4279d2660 mq_overview.7, sysvipc.7: Adjust references to namespaces(7) to ipc_namespaces(7) 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-08-26 23:14:49 +02:00
Michael Kerrisk 25e96f04bc namespaces.7: Remove content migrated to new ipc_namespaces(7) page 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-08-26 23:14:49 +02:00
Michael Kerrisk 1d36b4e17b ipc_namespaces.7: New page with content migrated from namespaces(7) 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-08-26 23:14:49 +02:00
Michael Kerrisk 3b9d44099f signal.7: Enhance the text on process-directed and thread-directed signals 
clone(2) has a good description of these concepts; borrow
from it liberally.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-08-26 23:14:42 +02:00
Michael Kerrisk 96e472175c signal.7: tfix 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-08-26 21:45:13 +02:00
Michael Kerrisk 18b028be2d user_namespaces.7: Improve explanation of meaning of ownership of nonuser namespaces 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-08-20 09:56:33 +02:00
Michael Kerrisk 7e7e8de32e capabilities.7: CAP_SYS_ADMIN allows modifying autogroup nice values 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-08-02 13:57:10 +02:00
Michael Kerrisk 63121bd499 pldd.1, bpf.2, chdir.2, clone.2, fanotify_init.2, fanotify_mark.2, intro.2, ipc.2, mount.2, mprotect.2, msgctl.2, msgget.2, msgop.2, pivot_root.2, pkey_alloc.2, poll.2, prctl.2, semctl.2, semget.2, semop.2, setxattr.2, shmctl.2, shmget.2, shmop.2, tkill.2, dlopen.3, exec.3, ftok.3, getutent.3, on_exit.3, strcat.3, cpuid.4, proc.5, capabilities.7, cgroup_namespaces.7, credentials.7, fanotify.7, mount_namespaces.7, namespaces.7, sched.7, signal.7, socket.7, unix.7, user_namespaces.7, vdso.7, xattr.7, ld.so.8: tstamp 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-08-02 08:34:32 +02:00
Michael Kerrisk fd6307c47f mount_namespaces.7: ffix 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-07-30 08:25:37 +02:00
Michael Kerrisk 2f368cc328 sched.7: SEE ALSO: add pthread_getschedparam(3) 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-07-30 08:25:37 +02:00
Michael Kerrisk 40ca38806d capabilities.7: Add pivot_root(2) to CAP_SYS_ADMIN list 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-07-28 13:34:28 +02:00
Michael Kerrisk dc95a3a39f mount_namespaces.7: Clarify implications for other NS if mount point is removed in one NS 
If a mount point is deleted or renamed or removed in one mount
namespace, this will cause an object that is mounted at that
location in another mount namespace to be unmounted (as verified
by experiment). This was implied by the existing text, but it is
better to make this detail explicit.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-07-24 07:11:35 +02:00
Michael Kerrisk 930e2ffac4 namespaces.7: srcfix 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-07-23 21:42:58 +02:00
Michael Kerrisk e70abf48ff mount_namespaces.7: SEE ALSO: add pivot_root(2), pivot_root(8) 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-07-22 20:59:38 +02:00
Michael Kerrisk ae4452ab98 namespaces.7: Note initial values of hostname and domainname in a new UTS namespace 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-07-20 23:50:50 +02:00
Michael Kerrisk 3b13efed75 capabilities.7: Add a note about using strace on binaries that have capabilities 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-07-17 04:19:01 +02:00
Michael Kerrisk 705ac54d0f signal.7: Minor text rework 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-07-13 12:18:08 -06:00
Michael Kerrisk 9b6aa9d133 signal.7: Some reworking of Michal Sekletar's text 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-07-13 12:15:32 -06:00
Michael Kerrisk cd9b34fc58 signal.7: Relocate Michal Sekletar's text 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-07-13 11:49:04 -06:00
Michal Sekletar e447e5bad3 signal.7: Clarify that siginfo_t isn't changed on coalescing 
Confirmed by experiment by mtk:

$ cat siginfo_nonqueuing.c

                        } while (0)

static void
grimReaper(int sig, siginfo_t *si, void *ucontext)
{
    printf("caught signal %d\n", sig);

    printf("    si_pid=%ld, si_uid=%ld, si_status=%d\n",
            (long) si->si_pid, (long) si->si_uid, si->si_status);
}

static void
child(int sleepTime, uid_t uid, int status)
{
    switch (fork()) {
    case -1:
        errExit("fork");
    case 0:
        sleep(sleepTime);
        if (geteuid() == 0)
            setuid(uid);

        printf("Child %ld with UID %ld exiting with status %d\n",
                (long) getpid(),(long) getuid(), status);
        exit(status);
    default:
        return;
    }
}

int
main(int argc, char *argv[])
{
    struct sigaction sa;
    sigset_t blocking;

    sa.sa_sigaction = grimReaper;
    sa.sa_flags = SA_SIGINFO;
    sigemptyset(&sa.sa_mask);

    if (sigaction(SIGCHLD, &sa, NULL) == -1)
        errExit("sigaction");

    sigemptyset(&blocking);
    sigaddset(&blocking, SIGCHLD);
    if (sigprocmask(SIG_BLOCK, &blocking, NULL) == -1)
        errExit("sigprocmask");

    child(2, 20000, 20);
    child(3, 30000, 30);
    child(1, 10000, 10);

    sleep(5);

    if (sigprocmask(SIG_UNBLOCK, &blocking, NULL) == -1)
        errExit("sigprocmask");

    exit(EXIT_SUCCESS);
}
$ ./siginfo_nonqueuing
Child 4042 with UID 1000 exiting with status 10
Child 4040 with UID 1000 exiting with status 20
Child 4041 with UID 1000 exiting with status 30
caught signal 17
    si_pid=4042, si_uid=1000, si_status=10

Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Lennart Poettering <lennart@poettering.net>

Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Michal Sekletar <msekleta@redhat.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-07-13 11:44:12 -06:00
Michael Kerrisk c7871135df signal.7: Add subsection on queuing and delivery semantics for standard signals 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-07-13 11:44:12 -06:00
Michael Kerrisk ed33c6886c credentials.7: Note that /proc/PID/status shows a process's credentials 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-07-10 15:44:47 +02:00
Michael Kerrisk aa16684c95 signal.7: Various fields in /proc/PID/status show signal-related information 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-07-10 15:19:31 +02:00
Michael Kerrisk b8cf6c2435 user_namespaces.7: Minor rewordings of recently added text 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-07-02 10:09:24 +02:00
Michael Kerrisk 89a0bd8283 user_namespaces.7: Minor wording fix to recently added text 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-07-02 06:20:44 +02:00
Michael Kerrisk 43f4bec190 user_namespaces.7: Describe the effect of file-related capabilities inside use namespaces 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-07-01 12:18:44 +02:00
Michael Kerrisk ea8ec5785c user_namespaces.7: Describe how kernel treats UIDs/GIDs when a process access to files 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-07-01 11:11:19 +02:00
Michael Kerrisk c99eb2b204 capabilities.7: CAP_FOWNER also allows modifying user xattrs on sticky directories 
See fs/xattr.c::xattr_permission()"

        /*
         * In the user.* namespace, only regular files and directories can have
         * extended attributes. For sticky directories, only the owner and
         * privileged users can write attributes.
         */
        if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) {
                if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
                        return (mask & MAY_WRITE) ? -EPERM : -ENODATA;
                if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&
                    (mask & MAY_WRITE) && !inode_owner_or_capable(inode))
                        return -EPERM;
        }

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-07-01 09:59:37 +02:00
Michael Kerrisk fc8d1db1b4 xattr.7: s/extended system attributes/system extended attributes/ 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-07-01 09:59:06 +02:00
Michael Kerrisk b25d3e704c xattr.7: wfix: s/extended user attributes/user extended attributes/ 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-07-01 09:59:06 +02:00
Michael Kerrisk e2340cf748 unix.7: Note SCM_RIGHTS interaction with RLIMIT_NOFILE 
If the file descriptors received in SCM_RIGHTS would cause
the process to its exceed RLIMIT_NOFILE limit, the excess
FDs are discarded.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-06-29 22:13:25 +02:00
Michael Kerrisk 015f61c72a svipc.7: Add old name of sysvipc(7) page as a link 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-06-25 06:39:05 +02:00
Michael Kerrisk 343cdc5ac9 clone.2, intro.2, ipc.2, msgctl.2, msgget.2, msgop.2, semctl.2, semget.2, semop.2, shmctl.2, shmget.2, shmop.2, ftok.3, proc.5, namespaces.7: Change reference to svipc(7) to sysvipc(7) 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-06-25 06:38:01 +02:00
Michael Kerrisk 880c105e22 sysvipc.7: Minor fixes for page renaming 
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
 2019-06-25 06:33:16 +02:00