The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x f1bb47a31dff6d4b34fb14e99850860ee74bb003 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable@xxxxxxxxxxxxxxx>' --in-reply-to '2024012636-appear-afford-1d24@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^.. Possible dependencies: f1bb47a31dff ("lsm: new security_file_ioctl_compat() hook") 98e828a0650f ("security: Refactor declaration of LSM hooks") 33c84e89abe4 ("Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From f1bb47a31dff6d4b34fb14e99850860ee74bb003 Mon Sep 17 00:00:00 2001 From: Alfred Piccioni <alpic@xxxxxxxxxx> Date: Tue, 19 Dec 2023 10:09:09 +0100 Subject: [PATCH] lsm: new security_file_ioctl_compat() hook Some ioctl commands do not require ioctl permission, but are routed to other permissions such as FILE_GETATTR or FILE_SETATTR. This routing is done by comparing the ioctl cmd to a set of 64-bit flags (FS_IOC_*). However, if a 32-bit process is running on a 64-bit kernel, it emits 32-bit flags (FS_IOC32_*) for certain ioctl operations. These flags are being checked erroneously, which leads to these ioctl operations being routed to the ioctl permission, rather than the correct file permissions. This was also noted in a RED-PEN finding from a while back - "/* RED-PEN how should LSM module know it's handling 32bit? */". This patch introduces a new hook, security_file_ioctl_compat(), that is called from the compat ioctl syscall. All current LSMs have been changed to support this hook. Reviewing the three places where we are currently using security_file_ioctl(), it appears that only SELinux needs a dedicated compat change; TOMOYO and SMACK appear to be functional without any change. Cc: stable@xxxxxxxxxxxxxxx Fixes: 0b24dcb7f2f7 ("Revert "selinux: simplify ioctl checking"") Signed-off-by: Alfred Piccioni <alpic@xxxxxxxxxx> Reviewed-by: Stephen Smalley <stephen.smalley.work@xxxxxxxxx> [PM: subject tweak, line length fixes, and alignment corrections] Signed-off-by: Paul Moore <paul@xxxxxxxxxxxxxx> diff --git a/fs/ioctl.c b/fs/ioctl.c index f5fd99d6b0d4..76cf22ac97d7 100644 --- a/fs/ioctl.c +++ b/fs/ioctl.c @@ -920,8 +920,7 @@ COMPAT_SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd, if (!f.file) return -EBADF; - /* RED-PEN how should LSM module know it's handling 32bit? */ - error = security_file_ioctl(f.file, cmd, arg); + error = security_file_ioctl_compat(f.file, cmd, arg); if (error) goto out; diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index c925a0d26edf..185924c56378 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -171,6 +171,8 @@ LSM_HOOK(int, 0, file_alloc_security, struct file *file) LSM_HOOK(void, LSM_RET_VOID, file_free_security, struct file *file) LSM_HOOK(int, 0, file_ioctl, struct file *file, unsigned int cmd, unsigned long arg) +LSM_HOOK(int, 0, file_ioctl_compat, struct file *file, unsigned int cmd, + unsigned long arg) LSM_HOOK(int, 0, mmap_addr, unsigned long addr) LSM_HOOK(int, 0, mmap_file, struct file *file, unsigned long reqprot, unsigned long prot, unsigned long flags) diff --git a/include/linux/security.h b/include/linux/security.h index 750130a7b9dd..d0eb20f90b26 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -394,6 +394,8 @@ int security_file_permission(struct file *file, int mask); int security_file_alloc(struct file *file); void security_file_free(struct file *file); int security_file_ioctl(struct file *file, unsigned int cmd, unsigned long arg); +int security_file_ioctl_compat(struct file *file, unsigned int cmd, + unsigned long arg); int security_mmap_file(struct file *file, unsigned long prot, unsigned long flags); int security_mmap_addr(unsigned long addr); @@ -1002,6 +1004,13 @@ static inline int security_file_ioctl(struct file *file, unsigned int cmd, return 0; } +static inline int security_file_ioctl_compat(struct file *file, + unsigned int cmd, + unsigned long arg) +{ + return 0; +} + static inline int security_mmap_file(struct file *file, unsigned long prot, unsigned long flags) { diff --git a/security/security.c b/security/security.c index d7b15ea67c3f..69148dfc90cd 100644 --- a/security/security.c +++ b/security/security.c @@ -2732,6 +2732,24 @@ int security_file_ioctl(struct file *file, unsigned int cmd, unsigned long arg) } EXPORT_SYMBOL_GPL(security_file_ioctl); +/** + * security_file_ioctl_compat() - Check if an ioctl is allowed in compat mode + * @file: associated file + * @cmd: ioctl cmd + * @arg: ioctl arguments + * + * Compat version of security_file_ioctl() that correctly handles 32-bit + * processes running on 64-bit kernels. + * + * Return: Returns 0 if permission is granted. + */ +int security_file_ioctl_compat(struct file *file, unsigned int cmd, + unsigned long arg) +{ + return call_int_hook(file_ioctl_compat, 0, file, cmd, arg); +} +EXPORT_SYMBOL_GPL(security_file_ioctl_compat); + static inline unsigned long mmap_prot(struct file *file, unsigned long prot) { /* diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index b340425ccfae..179540441115 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -3732,6 +3732,33 @@ static int selinux_file_ioctl(struct file *file, unsigned int cmd, return error; } +static int selinux_file_ioctl_compat(struct file *file, unsigned int cmd, + unsigned long arg) +{ + /* + * If we are in a 64-bit kernel running 32-bit userspace, we need to + * make sure we don't compare 32-bit flags to 64-bit flags. + */ + switch (cmd) { + case FS_IOC32_GETFLAGS: + cmd = FS_IOC_GETFLAGS; + break; + case FS_IOC32_SETFLAGS: + cmd = FS_IOC_SETFLAGS; + break; + case FS_IOC32_GETVERSION: + cmd = FS_IOC_GETVERSION; + break; + case FS_IOC32_SETVERSION: + cmd = FS_IOC_SETVERSION; + break; + default: + break; + } + + return selinux_file_ioctl(file, cmd, arg); +} + static int default_noexec __ro_after_init; static int file_map_prot_check(struct file *file, unsigned long prot, int shared) @@ -7122,6 +7149,7 @@ static struct security_hook_list selinux_hooks[] __ro_after_init = { LSM_HOOK_INIT(file_permission, selinux_file_permission), LSM_HOOK_INIT(file_alloc_security, selinux_file_alloc_security), LSM_HOOK_INIT(file_ioctl, selinux_file_ioctl), + LSM_HOOK_INIT(file_ioctl_compat, selinux_file_ioctl_compat), LSM_HOOK_INIT(mmap_file, selinux_mmap_file), LSM_HOOK_INIT(mmap_addr, selinux_mmap_addr), LSM_HOOK_INIT(file_mprotect, selinux_file_mprotect), diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 53336d7daa93..c126f6a16de4 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -5051,6 +5051,7 @@ static struct security_hook_list smack_hooks[] __ro_after_init = { LSM_HOOK_INIT(file_alloc_security, smack_file_alloc_security), LSM_HOOK_INIT(file_ioctl, smack_file_ioctl), + LSM_HOOK_INIT(file_ioctl_compat, smack_file_ioctl), LSM_HOOK_INIT(file_lock, smack_file_lock), LSM_HOOK_INIT(file_fcntl, smack_file_fcntl), LSM_HOOK_INIT(mmap_file, smack_mmap_file), diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c index e10491f155a5..3c3af149bf1c 100644 --- a/security/tomoyo/tomoyo.c +++ b/security/tomoyo/tomoyo.c @@ -574,6 +574,7 @@ static struct security_hook_list tomoyo_hooks[] __ro_after_init = { LSM_HOOK_INIT(path_rename, tomoyo_path_rename), LSM_HOOK_INIT(inode_getattr, tomoyo_inode_getattr), LSM_HOOK_INIT(file_ioctl, tomoyo_file_ioctl), + LSM_HOOK_INIT(file_ioctl_compat, tomoyo_file_ioctl), LSM_HOOK_INIT(path_chmod, tomoyo_path_chmod), LSM_HOOK_INIT(path_chown, tomoyo_path_chown), LSM_HOOK_INIT(path_chroot, tomoyo_path_chroot),
