Hi, after updating from AlmaLinux 9.4 to 9.5 (https://repo.almalinux.org/vault/9.4/BaseOS/Source/Packages/kernel-5.14.0-427.40.1.el9_4.src.rpm vs. https://repo.almalinux.org/vault/9.5/BaseOS/Source/Packages/kernel-5.14.0-503.15.1.el9_5.src.rpm), chmod gets ignored by the CIFS filesystem when executed against a Windows file server unless chmod happens in another process. Mount options as reported by mount: rw,relatime,context=system_u:object_r:tmp_t:s0,vers=3.1.1,cache=strict,username=<username> uid=0,noforceuid,gid=0,noforcegid,addr=<addr>,file_mode=0755,dir_mode=0755,soft nounix,serverino,mapposix,reparse=nfs,rsize=4194304,wsize=4194304,bsize=1048576 retrans=1,echo_interval=60,actimeo=1,closetimeo=1 Reproduction (see source below): ./test <path/to/mountpoint>/<non-existent-filename> all Unexpected mode 100555 strace: openat(AT_FDCWD, "/mnt/test", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 3 close(3) = 0 chmod("/mnt/test", 0400) = 0 openat(AT_FDCWD, "/mnt/test", O_RDONLY) = 3 close(3) = 0 newfstatat(AT_FDCWD, "/mnt/test", {st_dev=makedev(0, 0x2b), st_ino=1407374884039565, st_mode=S_IFREG|0555, st_nlink=1, st_uid=0, st_gid=0, st_blksize=1048576, st_blocks=0, st_size=0, st_atime=17 37759300 /* 2025-01-24T23:55:00.242552200+0100 */, st_atime_nsec=242552200, st_mtime=1737759300 /* 2025-01-24T23:55:00.242552200+0100 */, st_mtime_nsec=242552200, st_ctime=1737759300 /* 2025-01- 24T23:55:00.243552200+0100 */, st_ctime_nsec=243552200}, 0) = 0 chmod("/mnt/test", 0600) = 0 newfstatat(AT_FDCWD, "/mnt/test", {st_dev=makedev(0, 0x2b), st_ino=1407374884039565, st_mode=S_IFREG|0555, st_nlink=1, st_uid=0, st_gid=0, st_blksize=1048576, st_blocks=0, st_size=0, st_atime=17 37759300 /* 2025-01-24T23:55:00.242552200+0100 */, st_atime_nsec=242552200, st_mtime=1737759300 /* 2025-01-24T23:55:00.242552200+0100 */, st_mtime_nsec=242552200, st_ctime=1737759300 /* 2025-01- 24T23:55:00.245552200+0100 */, st_ctime_nsec=245552200}, 0) = 0 write(2, "Unexpected mode 100555\n", 23Unexpected mode 100555 ) = 23 exit_group(1) = ? +++ exited with 1 +++ Workaround (executing the test in two processes): ./test <path/to/mountpoint>/<non-existent-filename> first ./test <path/to/mountpoint>/<non-existent-filename> last strace: openat(AT_FDCWD, "/mnt/test", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 3 close(3) = 0 chmod("/mnt/test", 0400) = 0 openat(AT_FDCWD, "/mnt/test", O_RDONLY) = 3 close(3) = 0 exit_group(0) = ? +++ exited with 0 +++ newfstatat(AT_FDCWD, "/mnt/test", {st_dev=makedev(0, 0x2b), st_ino=1407374884039566, st_mode=S_IFREG|0555, st_nlink=1, st_uid=0, st_gid=0, st_blksize=1048576, st_blocks=0, st_size=0, st_atime=17 37759424 /* 2025-01-24T23:57:04.152930200+0100 */, st_atime_nsec=152930200, st_mtime=1737759424 /* 2025-01-24T23:57:04.152930200+0100 */, st_mtime_nsec=152930200, st_ctime=1737759424 /* 2025-01- 24T23:57:04.152930200+0100 */, st_ctime_nsec=152930200}, 0) = 0 chmod("/mnt/test", 0600) = 0 newfstatat(AT_FDCWD, "/mnt/test", {st_dev=makedev(0, 0x2b), st_ino=1407374884039566, st_mode=S_IFREG|0755, st_nlink=1, st_uid=0, st_gid=0, st_blksize=1048576, st_blocks=0, st_size=0, st_atime=17 37759424 /* 2025-01-24T23:57:04.152930200+0100 */, st_atime_nsec=152930200, st_mtime=1737759424 /* 2025-01-24T23:57:04.152930200+0100 */, st_mtime_nsec=152930200, st_ctime=1737759449 /* 2025-01- 24T23:57:29.621213500+0100 */, st_ctime_nsec=621213500}, 0) = 0 openat(AT_FDCWD, "/mnt/test", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 3 close(3) = 0 exit_group(0) = ? +++ exited with 0 +++ Please let me know if your can reproduce the issue using the sample. Cheers, Horst Reiterer test.c: #include <fcntl.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/stat.h> #include <sys/types.h> #include <unistd.h> int main(int argc, char *argv[]) { if (argc != 3) { fprintf(stderr, "test <path> <all|first|last>\n"); return 2; } char *path = argv[1]; char *mode = argv[2]; int fd; if (strcmp(mode, "all") == 0 || strcmp(mode, "first") == 0) { if ((fd = open(path, O_WRONLY|O_CREAT|O_TRUNC, 0666)) == -1) { perror("open"); return 1; } close(fd); if (chmod(path, 0400) == -1) { perror("chmod"); return 1; } if ((fd = open(path, O_RDONLY)) == -1) { perror("open"); return 1; } close(fd); } if (strcmp(mode, "all") == 0 || strcmp(mode, "last") == 0) { struct stat statbuf; if (stat(path, &statbuf) == -1) { perror("stat"); return 1; } mode_t modebefore = statbuf.st_mode; if (chmod(path, 0600) == -1) { perror("chmod"); return 1; } if (stat(path, &statbuf) == -1) { perror("stat"); return 1; } if (statbuf.st_mode == modebefore) { fprintf(stderr, "Unexpected mode %o\n", statbuf.st_mode); return 1; } if ((fd = open(path, O_WRONLY|O_CREAT|O_TRUNC, 0666)) == -1) { perror("open"); return 1; } close(fd); } return 0; }
