[OE-core] [PATCH v3] pseudo: Fix openat() with a symlink pointing to a directory

[Jason Wessel]

While working with ostree disk generation in conjunction with wic, I
found a problem with pseudo where it tried to resolve a symlink when
it shouldn't, based on openat() flags. A C program has been
constructed to test pseudo to show that it is working properly with
the correct behavior around openat().

 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <dirent.h>
 #include <unistd.h>
 #include <fcntl.h>

int main()
{
    /*
     * Tested with: gcc -Wall -o app app.c ; echo "no pseudo" ;
     * ./app ; echo "pseudo"; pseudo ./app
     */
    system("rm -rf tdir tlink");
    system("mkdir tdir");
    system("ln -s tdir tlink");
    DIR *dir = opendir(".");
    int dfd = dirfd(dir);

    int target_dfd = openat (dfd, "tlink", O_RDONLY | O_NONBLOCK |
                             O_DIRECTORY | O_CLOEXEC | O_NOFOLLOW);
    if (target_dfd == -1) {
        printf("Test 1 good\n");
    } else {
        printf("Test 1 failed\n");
        close(target_dfd);
    }
    target_dfd = openat (dfd, "tlink", O_RDONLY | O_NONBLOCK |
                         O_DIRECTORY | O_CLOEXEC);
    if (target_dfd == -1) {
        printf("Test 2 failed\n");
    } else {
        printf("Test 2 good\n");
        close(target_dfd);
    }
    /* Test 3 make sure the owner of the link is root  */
    struct stat sbuf;
    if (!lstat("tlink", &sbuf) && sbuf.st_uid == 0) {
        printf("Test 3 good\n");
    } else {
        printf("Test 3 failed\n");
    }
    /* Test 4 tests open with the "rb" flag, owner should not change */
    int ofd = openat(dfd,"./tlink", O_RDONLY|O_CLOEXEC);
    if (ofd >= 0) {
        if (fstat(ofd, &sbuf) != 0)
            printf("ERROR in fstat test 4\n");
        else if (sbuf.st_uid == 0)
            printf("Test 4 good\n");
        close(ofd);
    } else {
        printf("Test 4 failed with openat()\n");
    }
    /* Test pseudo db to see the fstat() above did not delete the DB entry */
    if (!lstat("tlink", &sbuf) && sbuf.st_uid == 0)
        printf("Test 5 good\n");
    else
        printf("Test 5 failed... tlink is owned by %i and not 0\n", sbuf.st_uid);
    return 0;
}

int main()
{
    /* Tested with: gcc -Wall -o app app.c ; echo "no pseudo" ; ./app ; echo "pseudo"; pseudo ./app */
    system("rm -rf tdir tlink");
    system("mkdir tdir");
    system("ln -s tdir tlink");
    DIR *dir = opendir(".");
    int dfd = dirfd(dir);

    int target_dfd = openat (dfd, "tlink", O_RDONLY | O_NONBLOCK | O_DIRECTORY | O_CLOEXEC | O_NOFOLLOW);
    if (target_dfd == -1) {
        printf("This is right\n");
    } else {
        printf("This is broken\n");
    }
    return 0;
}

Many thanks to Peter Seebach for fixing the problem in the pseudo code
to use the same logic which was already there for the
AT_SYMLINK_NOFOLLOW.

Also updated is the license MD5 checksum since the master branch of
pseudo has had the SPDX data updated.

Signed-off-by: Jason Wessel <jason.wessel at windriver.com>
---
 meta/recipes-devtools/pseudo/pseudo.inc    | 2 +-
 meta/recipes-devtools/pseudo/pseudo_git.bb | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/meta/recipes-devtools/pseudo/pseudo.inc b/meta/recipes-devtools/pseudo/pseudo.inc
index 8b05735bb1..8b34909726 100644
--- a/meta/recipes-devtools/pseudo/pseudo.inc
+++ b/meta/recipes-devtools/pseudo/pseudo.inc
@@ -4,7 +4,7 @@
 
 SUMMARY = "Pseudo gives fake root capabilities to a normal user"
 HOMEPAGE = "http://git.yoctoproject.org/cgit/cgit.cgi/pseudo"
-LIC_FILES_CHKSUM = "file://COPYING;md5=243b725d71bb5df4a1e5920b344b86ad"
+LIC_FILES_CHKSUM = "file://COPYING;md5=a1d8023a6f953ac6ea4af765ff62d574"
 SECTION = "base"
 LICENSE = "LGPL2.1"
 DEPENDS = "sqlite3 attr"
diff --git a/meta/recipes-devtools/pseudo/pseudo_git.bb b/meta/recipes-devtools/pseudo/pseudo_git.bb
index 51db84c4d4..6cf711e4c2 100644
--- a/meta/recipes-devtools/pseudo/pseudo_git.bb
+++ b/meta/recipes-devtools/pseudo/pseudo_git.bb
@@ -8,7 +8,7 @@ SRC_URI = "git://git.yoctoproject.org/pseudo \
            file://toomanyfiles.patch \
            "
 
-SRCREV = "3fa7c853e0bcd6fe23f7524c2a3c9e3af90901c3"
+SRCREV = "060058bb29f70b244e685b3c704eb0641b736f73"
 S = "${WORKDIR}/git"
 PV = "1.9.0+git${SRCPV}"
 
-- 
2.21.0