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authorLinus Torvalds <torvalds@linux-foundation.org>2020-06-04 14:07:08 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-04 14:07:08 -0700
commit15a2bc4dbb9cfed1c661a657fcb10798150b7598 (patch)
treef9ca834dbdd2e6cf1d5a2cef5008f82c72b00261
parent9ff7258575d5fee011649d20cc56de720a395191 (diff)
parent3977e285ee89a94699255dbbf6eeea13889a1083 (diff)
downloadlinux-stericsson-15a2bc4dbb9cfed1c661a657fcb10798150b7598.tar.gz
Merge branch 'exec-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull execve updates from Eric Biederman: "Last cycle for the Nth time I ran into bugs and quality of implementation issues related to exec that could not be easily be fixed because of the way exec is implemented. So I have been digging into exec and cleanup up what I can. I don't think I have exec sorted out enough to fix the issues I started with but I have made some headway this cycle with 4 sets of changes. - promised cleanups after introducing exec_update_mutex - trivial cleanups for exec - control flow simplifications - remove the recomputation of bprm->cred The net result is code that is a bit easier to understand and work with and a decrease in the number of lines of code (if you don't count the added tests)" * 'exec-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (24 commits) exec: Compute file based creds only once exec: Add a per bprm->file version of per_clear binfmt_elf_fdpic: fix execfd build regression selftests/exec: Add binfmt_script regression test exec: Remove recursion from search_binary_handler exec: Generic execfd support exec/binfmt_script: Don't modify bprm->buf and then return -ENOEXEC exec: Move the call of prepare_binprm into search_binary_handler exec: Allow load_misc_binary to call prepare_binprm unconditionally exec: Convert security_bprm_set_creds into security_bprm_repopulate_creds exec: Factor security_bprm_creds_for_exec out of security_bprm_set_creds exec: Teach prepare_exec_creds how exec treats uids & gids exec: Set the point of no return sooner exec: Move handling of the point of no return to the top level exec: Run sync_mm_rss before taking exec_update_mutex exec: Fix spelling of search_binary_handler in a comment exec: Move the comment from above de_thread to above unshare_sighand exec: Rename flush_old_exec begin_new_exec exec: Move most of setup_new_exec into flush_old_exec exec: In setup_new_exec cache current in the local variable me ...
-rw-r--r--Documentation/trace/ftrace.rst2
-rw-r--r--arch/alpha/kernel/binfmt_loader.c11
-rw-r--r--arch/x86/ia32/ia32_aout.c4
-rw-r--r--fs/binfmt_aout.c3
-rw-r--r--fs/binfmt_elf.c7
-rw-r--r--fs/binfmt_elf_fdpic.c9
-rw-r--r--fs/binfmt_em86.c13
-rw-r--r--fs/binfmt_flat.c4
-rw-r--r--fs/binfmt_misc.c69
-rw-r--r--fs/binfmt_script.c82
-rw-r--r--fs/exec.c316
-rw-r--r--include/linux/binfmts.h45
-rw-r--r--include/linux/lsm_hook_defs.h3
-rw-r--r--include/linux/lsm_hooks.h56
-rw-r--r--include/linux/security.h15
-rw-r--r--kernel/cred.c3
-rw-r--r--kernel/events/core.c2
-rw-r--r--security/apparmor/domain.c7
-rw-r--r--security/apparmor/include/domain.h2
-rw-r--r--security/apparmor/lsm.c2
-rw-r--r--security/commoncap.c23
-rw-r--r--security/security.c9
-rw-r--r--security/selinux/hooks.c8
-rw-r--r--security/smack/smack_lsm.c9
-rw-r--r--security/tomoyo/tomoyo.c12
-rw-r--r--tools/testing/selftests/exec/Makefile1
-rwxr-xr-xtools/testing/selftests/exec/binfmt_script171
27 files changed, 501 insertions, 387 deletions
diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst
index 3b5614b1d1a5..430a16283103 100644
--- a/Documentation/trace/ftrace.rst
+++ b/Documentation/trace/ftrace.rst
@@ -1524,7 +1524,7 @@ display-graph option::
=> remove_vma
=> exit_mmap
=> mmput
- => flush_old_exec
+ => begin_new_exec
=> load_elf_binary
=> search_binary_handler
=> __do_execve_file.isra.32
diff --git a/arch/alpha/kernel/binfmt_loader.c b/arch/alpha/kernel/binfmt_loader.c
index a8d0d6e06526..e4be7a543ecf 100644
--- a/arch/alpha/kernel/binfmt_loader.c
+++ b/arch/alpha/kernel/binfmt_loader.c
@@ -19,10 +19,6 @@ static int load_binary(struct linux_binprm *bprm)
if (bprm->loader)
return -ENOEXEC;
- allow_write_access(bprm->file);
- fput(bprm->file);
- bprm->file = NULL;
-
loader = bprm->vma->vm_end - sizeof(void *);
file = open_exec("/sbin/loader");
@@ -33,12 +29,9 @@ static int load_binary(struct linux_binprm *bprm)
/* Remember if the application is TASO. */
bprm->taso = eh->ah.entry < 0x100000000UL;
- bprm->file = file;
+ bprm->interpreter = file;
bprm->loader = loader;
- retval = prepare_binprm(bprm);
- if (retval < 0)
- return retval;
- return search_binary_handler(bprm);
+ return 0;
}
static struct linux_binfmt loader_format = {
diff --git a/arch/x86/ia32/ia32_aout.c b/arch/x86/ia32/ia32_aout.c
index 9bb71abd66bd..385d3d172ee1 100644
--- a/arch/x86/ia32/ia32_aout.c
+++ b/arch/x86/ia32/ia32_aout.c
@@ -131,7 +131,7 @@ static int load_aout_binary(struct linux_binprm *bprm)
return -ENOMEM;
/* Flush all traces of the currently running executable */
- retval = flush_old_exec(bprm);
+ retval = begin_new_exec(bprm);
if (retval)
return retval;
@@ -156,8 +156,6 @@ static int load_aout_binary(struct linux_binprm *bprm)
if (retval < 0)
return retval;
- install_exec_creds(bprm);
-
if (N_MAGIC(ex) == OMAGIC) {
unsigned long text_addr, map_size;
diff --git a/fs/binfmt_aout.c b/fs/binfmt_aout.c
index 8e8346a81723..3e84e9bb9084 100644
--- a/fs/binfmt_aout.c
+++ b/fs/binfmt_aout.c
@@ -151,7 +151,7 @@ static int load_aout_binary(struct linux_binprm * bprm)
return -ENOMEM;
/* Flush all traces of the currently running executable */
- retval = flush_old_exec(bprm);
+ retval = begin_new_exec(bprm);
if (retval)
return retval;
@@ -174,7 +174,6 @@ static int load_aout_binary(struct linux_binprm * bprm)
if (retval < 0)
return retval;
- install_exec_creds(bprm);
if (N_MAGIC(ex) == OMAGIC) {
unsigned long text_addr, map_size;
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 8945671fe0e5..44813ceecc47 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -279,8 +279,8 @@ create_elf_tables(struct linux_binprm *bprm, const struct elfhdr *exec,
NEW_AUX_ENT(AT_BASE_PLATFORM,
(elf_addr_t)(unsigned long)u_base_platform);
}
- if (bprm->interp_flags & BINPRM_FLAGS_EXECFD) {
- NEW_AUX_ENT(AT_EXECFD, bprm->interp_data);
+ if (bprm->have_execfd) {
+ NEW_AUX_ENT(AT_EXECFD, bprm->execfd);
}
#undef NEW_AUX_ENT
/* AT_NULL is zero; clear the rest too */
@@ -975,7 +975,7 @@ out_free_interp:
goto out_free_dentry;
/* Flush all traces of the currently running executable */
- retval = flush_old_exec(bprm);
+ retval = begin_new_exec(bprm);
if (retval)
goto out_free_dentry;
@@ -989,7 +989,6 @@ out_free_interp:
current->flags |= PF_RANDOMIZE;
setup_new_exec(bprm);
- install_exec_creds(bprm);
/* Do this so that we can load the interpreter, if need be. We will
change some of these later */
diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index d9501a86cec9..aaf332d32326 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -338,7 +338,7 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm)
interp_params.flags |= ELF_FDPIC_FLAG_CONSTDISP;
/* flush all traces of the currently running executable */
- retval = flush_old_exec(bprm);
+ retval = begin_new_exec(bprm);
if (retval)
goto error;
@@ -434,7 +434,6 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm)
current->mm->start_stack = current->mm->start_brk + stack_size;
#endif
- install_exec_creds(bprm);
if (create_elf_fdpic_tables(bprm, current->mm,
&exec_params, &interp_params) < 0)
goto error;
@@ -589,7 +588,7 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm,
nitems = 1 + DLINFO_ITEMS + (k_platform ? 1 : 0) +
(k_base_platform ? 1 : 0) + AT_VECTOR_SIZE_ARCH;
- if (bprm->interp_flags & BINPRM_FLAGS_EXECFD)
+ if (bprm->have_execfd)
nitems++;
csp = sp;
@@ -629,10 +628,10 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm,
(elf_addr_t) (unsigned long) u_base_platform);
}
- if (bprm->interp_flags & BINPRM_FLAGS_EXECFD) {
+ if (bprm->have_execfd) {
nr = 0;
csp -= 2 * sizeof(unsigned long);
- NEW_AUX_ENT(AT_EXECFD, bprm->interp_data);
+ NEW_AUX_ENT(AT_EXECFD, bprm->execfd);
}
nr = 0;
diff --git a/fs/binfmt_em86.c b/fs/binfmt_em86.c
index 466497860c62..995883693cb2 100644
--- a/fs/binfmt_em86.c
+++ b/fs/binfmt_em86.c
@@ -48,10 +48,6 @@ static int load_em86(struct linux_binprm *bprm)
if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE)
return -ENOENT;
- allow_write_access(bprm->file);
- fput(bprm->file);
- bprm->file = NULL;
-
/* Unlike in the script case, we don't have to do any hairy
* parsing to find our interpreter... it's hardcoded!
*/
@@ -89,13 +85,8 @@ static int load_em86(struct linux_binprm *bprm)
if (IS_ERR(file))
return PTR_ERR(file);
- bprm->file = file;
-
- retval = prepare_binprm(bprm);
- if (retval < 0)
- return retval;
-
- return search_binary_handler(bprm);
+ bprm->interpreter = file;
+ return 0;
}
static struct linux_binfmt em86_format = {
diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 831a2b25ba79..9b82bc111d0a 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -534,7 +534,7 @@ static int load_flat_file(struct linux_binprm *bprm,
/* Flush all traces of the currently running executable */
if (id == 0) {
- ret = flush_old_exec(bprm);
+ ret = begin_new_exec(bprm);
if (ret)
goto err;
@@ -963,8 +963,6 @@ static int load_flat_binary(struct linux_binprm *bprm)
}
}
- install_exec_creds(bprm);
-
set_binfmt(&flat_format);
#ifdef CONFIG_MMU
diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
index cdb45829354d..bc5506619b7e 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -134,7 +134,6 @@ static int load_misc_binary(struct linux_binprm *bprm)
Node *fmt;
struct file *interp_file = NULL;
int retval;
- int fd_binary = -1;
retval = -ENOEXEC;
if (!enabled)
@@ -160,51 +159,25 @@ static int load_misc_binary(struct linux_binprm *bprm)
goto ret;
}
- if (fmt->flags & MISC_FMT_OPEN_BINARY) {
+ if (fmt->flags & MISC_FMT_OPEN_BINARY)
+ bprm->have_execfd = 1;
- /* if the binary should be opened on behalf of the
- * interpreter than keep it open and assign descriptor
- * to it
- */
- fd_binary = get_unused_fd_flags(0);
- if (fd_binary < 0) {
- retval = fd_binary;
- goto ret;
- }
- fd_install(fd_binary, bprm->file);
-
- /* if the binary is not readable than enforce mm->dumpable=0
- regardless of the interpreter's permissions */
- would_dump(bprm, bprm->file);
-
- allow_write_access(bprm->file);
- bprm->file = NULL;
-
- /* mark the bprm that fd should be passed to interp */
- bprm->interp_flags |= BINPRM_FLAGS_EXECFD;
- bprm->interp_data = fd_binary;
-
- } else {
- allow_write_access(bprm->file);
- fput(bprm->file);
- bprm->file = NULL;
- }
/* make argv[1] be the path to the binary */
retval = copy_strings_kernel(1, &bprm->interp, bprm);
if (retval < 0)
- goto error;
+ goto ret;
bprm->argc++;
/* add the interp as argv[0] */
retval = copy_strings_kernel(1, &fmt->interpreter, bprm);
if (retval < 0)
- goto error;
+ goto ret;
bprm->argc++;
/* Update interp in case binfmt_script needs it. */
retval = bprm_change_interp(fmt->interpreter, bprm);
if (retval < 0)
- goto error;
+ goto ret;
if (fmt->flags & MISC_FMT_OPEN_FILE) {
interp_file = file_clone_open(fmt->interp_file);
@@ -215,38 +188,16 @@ static int load_misc_binary(struct linux_binprm *bprm)
}
retval = PTR_ERR(interp_file);
if (IS_ERR(interp_file))
- goto error;
-
- bprm->file = interp_file;
- if (fmt->flags & MISC_FMT_CREDENTIALS) {
- loff_t pos = 0;
-
- /*
- * No need to call prepare_binprm(), it's already been
- * done. bprm->buf is stale, update from interp_file.
- */
- memset(bprm->buf, 0, BINPRM_BUF_SIZE);
- retval = kernel_read(bprm->file, bprm->buf, BINPRM_BUF_SIZE,
- &pos);
- } else
- retval = prepare_binprm(bprm);
-
- if (retval < 0)
- goto error;
+ goto ret;
- retval = search_binary_handler(bprm);
- if (retval < 0)
- goto error;
+ bprm->interpreter = interp_file;
+ if (fmt->flags & MISC_FMT_CREDENTIALS)
+ bprm->execfd_creds = 1;
+ retval = 0;
ret:
dput(fmt->dentry);
return retval;
-error:
- if (fd_binary > 0)
- ksys_close(fd_binary);
- bprm->interp_flags = 0;
- bprm->interp_data = 0;
- goto ret;
}
/* Command parsers */
diff --git a/fs/binfmt_script.c b/fs/binfmt_script.c
index e9e6a6f4a35f..0e8b953d12cf 100644
--- a/fs/binfmt_script.c
+++ b/fs/binfmt_script.c
@@ -16,14 +16,14 @@
#include <linux/fs.h>
static inline bool spacetab(char c) { return c == ' ' || c == '\t'; }
-static inline char *next_non_spacetab(char *first, const char *last)
+static inline const char *next_non_spacetab(const char *first, const char *last)
{
for (; first <= last; first++)
if (!spacetab(*first))
return first;
return NULL;
}
-static inline char *next_terminator(char *first, const char *last)
+static inline const char *next_terminator(const char *first, const char *last)
{
for (; first <= last; first++)
if (spacetab(*first) || !*first)
@@ -33,8 +33,7 @@ static inline char *next_terminator(char *first, const char *last)
static int load_script(struct linux_binprm *bprm)
{
- const char *i_arg, *i_name;
- char *cp, *buf_end;
+ const char *i_name, *i_sep, *i_arg, *i_end, *buf_end;
struct file *file;
int retval;
@@ -43,20 +42,6 @@ static int load_script(struct linux_binprm *bprm)
return -ENOEXEC;
/*
- * If the script filename will be inaccessible after exec, typically
- * because it is a "/dev/fd/<fd>/.." path against an O_CLOEXEC fd, give
- * up now (on the assumption that the interpreter will want to load
- * this file).
- */
- if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE)
- return -ENOENT;
-
- /* Release since we are not mapping a binary into memory. */
- allow_write_access(bprm->file);
- fput(bprm->file);
- bprm->file = NULL;
-
- /*
* This section handles parsing the #! line into separate
* interpreter path and argument strings. We must be careful
* because bprm->buf is not yet guaranteed to be NUL-terminated
@@ -71,39 +56,43 @@ static int load_script(struct linux_binprm *bprm)
* parse them on its own.
*/
buf_end = bprm->buf + sizeof(bprm->buf) - 1;
- cp = strnchr(bprm->buf, sizeof(bprm->buf), '\n');
- if (!cp) {
- cp = next_non_spacetab(bprm->buf + 2, buf_end);
- if (!cp)
+ i_end = strnchr(bprm->buf, sizeof(bprm->buf), '\n');
+ if (!i_end) {
+ i_end = next_non_spacetab(bprm->buf + 2, buf_end);
+ if (!i_end)
return -ENOEXEC; /* Entire buf is spaces/tabs */
/*
* If there is no later space/tab/NUL we must assume the
* interpreter path is truncated.
*/
- if (!next_terminator(cp, buf_end))
+ if (!next_terminator(i_end, buf_end))
return -ENOEXEC;
- cp = buf_end;
+ i_end = buf_end;
}
- /* NUL-terminate the buffer and any trailing spaces/tabs. */
- *cp = '\0';
- while (cp > bprm->buf) {
- cp--;
- if ((*cp == ' ') || (*cp == '\t'))
- *cp = '\0';
- else
- break;
- }
- for (cp = bprm->buf+2; (*cp == ' ') || (*cp == '\t'); cp++);
- if (*cp == '\0')
+ /* Trim any trailing spaces/tabs from i_end */
+ while (spacetab(i_end[-1]))
+ i_end--;
+
+ /* Skip over leading spaces/tabs */
+ i_name = next_non_spacetab(bprm->buf+2, i_end);
+ if (!i_name || (i_name == i_end))
return -ENOEXEC; /* No interpreter name found */
- i_name = cp;
+
+ /* Is there an optional argument? */
i_arg = NULL;
- for ( ; *cp && (*cp != ' ') && (*cp != '\t'); cp++)
- /* nothing */ ;
- while ((*cp == ' ') || (*cp == '\t'))
- *cp++ = '\0';
- if (*cp)
- i_arg = cp;
+ i_sep = next_terminator(i_name, i_end);
+ if (i_sep && (*i_sep != '\0'))
+ i_arg = next_non_spacetab(i_sep, i_end);
+
+ /*
+ * If the script filename will be inaccessible after exec, typically
+ * because it is a "/dev/fd/<fd>/.." path against an O_CLOEXEC fd, give
+ * up now (on the assumption that the interpreter will want to load
+ * this file).
+ */
+ if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE)
+ return -ENOENT;
+
/*
* OK, we've parsed out the interpreter name and
* (optional) argument.
@@ -121,7 +110,9 @@ static int load_script(struct linux_binprm *bprm)
if (retval < 0)
return retval;
bprm->argc++;
+ *((char *)i_end) = '\0';
if (i_arg) {
+ *((char *)i_sep) = '\0';
retval = copy_strings_kernel(1, &i_arg, bprm);
if (retval < 0)
return retval;
@@ -142,11 +133,8 @@ static int load_script(struct linux_binprm *bprm)
if (IS_ERR(file))
return PTR_ERR(file);
- bprm->file = file;
- retval = prepare_binprm(bprm);
- if (retval < 0)
- return retval;
- return search_binary_handler(bprm);
+ bprm->interpreter = file;
+ return 0;
}
static struct linux_binfmt script_format = {
diff --git a/fs/exec.c b/fs/exec.c
index 2f0a74582ac9..e850ee7dd636 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -72,6 +72,8 @@
#include <trace/events/sched.h>
+static int bprm_creds_from_file(struct linux_binprm *bprm);
+
int suid_dumpable = 0;
static LIST_HEAD(formats);
@@ -1051,13 +1053,14 @@ static int exec_mmap(struct mm_struct *mm)
tsk = current;
old_mm = current->mm;
exec_mm_release(tsk, old_mm);
+ if (old_mm)
+ sync_mm_rss(old_mm);
ret = mutex_lock_killable(&tsk->signal->exec_update_mutex);
if (ret)
return ret;
if (old_mm) {
- sync_mm_rss(old_mm);
/*
* Make sure that if there is a core dump in progress
* for the old mm, we get out and die instead of going
@@ -1093,12 +1096,6 @@ static int exec_mmap(struct mm_struct *mm)
return 0;
}
-/*
- * This function makes sure the current process has its own signal table,
- * so that flush_signal_handlers can later reset the handlers without
- * disturbing other processes. (Other processes might share the signal
- * table via the CLONE_SIGHAND option to clone().)
- */
static int de_thread(struct task_struct *tsk)
{
struct signal_struct *sig = tsk->signal;
@@ -1236,6 +1233,12 @@ killed:
}
+/*
+ * This function makes sure the current process has its own signal table,
+ * so that flush_signal_handlers can later reset the handlers without
+ * disturbing other processes. (Other processes might share the signal
+ * table via the CLONE_SIGHAND option to clone().)
+ */
static int unshare_sighand(struct task_struct *me)
{
struct sighand_struct *oldsighand = me->sighand;
@@ -1292,13 +1295,23 @@ void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
* Calling this is the point of no return. None of the failures will be
* seen by userspace since either the process is already taking a fatal
* signal (via de_thread() or coredump), or will have SEGV raised
- * (after exec_mmap()) by search_binary_handlers (see below).
+ * (after exec_mmap()) by search_binary_handler (see below).
*/
-int flush_old_exec(struct linux_binprm * bprm)
+int begin_new_exec(struct linux_binprm * bprm)
{
struct task_struct *me = current;
int retval;
+ /* Once we are committed compute the creds */
+ retval = bprm_creds_from_file(bprm);
+ if (retval)
+ return retval;
+
+ /*
+ * Ensure all future errors are fatal.
+ */
+ bprm->point_of_no_return = true;
+
/*
* Make this the only thread in the thread group.
*/
@@ -1313,7 +1326,10 @@ int flush_old_exec(struct linux_binprm * bprm)
*/
set_mm_exe_file(bprm->mm, bprm->file);
+ /* If the binary is not readable then enforce mm->dumpable=0 */
would_dump(bprm, bprm->file);
+ if (bprm->have_execfd)
+ would_dump(bprm, bprm->executable);
/*
* Release all of the old mmap stuff
@@ -1323,13 +1339,6 @@ int flush_old_exec(struct linux_binprm * bprm)
if (retval)
goto out;
- /*
- * After setting bprm->called_exec_mmap (to mark that current is
- * using the prepared mm now), we have nothing left of the original
- * process. If anything from here on returns an error, the check
- * in search_binary_handler() will SEGV current.
- */
- bprm->called_exec_mmap = 1;
bprm->mm = NULL;
#ifdef CONFIG_POSIX_TIMERS
@@ -1342,7 +1351,7 @@ int flush_old_exec(struct linux_binprm * bprm)
*/
retval = unshare_sighand(me);
if (retval)
- goto out;
+ goto out_unlock;
set_fs(USER_DS);
me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD |
@@ -1357,12 +1366,84 @@ int flush_old_exec(struct linux_binprm * bprm)
* undergoing exec(2).
*/
do_close_on_exec(me->files);
+
+ if (bprm->secureexec) {
+ /* Make sure parent cannot signal privileged process. */
+ me->pdeath_signal = 0;
+
+ /*
+ * For secureexec, reset the stack limit to sane default to
+ * avoid bad behavior from the prior rlimits. This has to
+ * happen before arch_pick_mmap_layout(), which examines
+ * RLIMIT_STACK, but after the point of no return to avoid
+ * needing to clean up the change on failure.
+ */
+ if (bprm->rlim_stack.rlim_cur > _STK_LIM)
+ bprm->rlim_stack.rlim_cur = _STK_LIM;
+ }
+
+ me->sas_ss_sp = me->sas_ss_size = 0;
+
+ /*
+ * Figure out dumpability. Note that this checking only of current
+ * is wrong, but userspace depends on it. This should be testing
+ * bprm->secureexec instead.
+ */
+ if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP ||
+ !(uid_eq(current_euid(), current_uid()) &&
+ gid_eq(current_egid(), current_gid())))
+ set_dumpable(current->mm, suid_dumpable);
+ else
+ set_dumpable(current->mm, SUID_DUMP_USER);
+
+ perf_event_exec();
+ __set_task_comm(me, kbasename(bprm->filename), true);
+
+ /* An exec changes our domain. We are no longer part of the thread
+ group */
+ WRITE_ONCE(me->self_exec_id, me->self_exec_id + 1);
+ flush_signal_handlers(me, 0);
+
+ /*
+ * install the new credentials for this executable
+ */
+ security_bprm_committing_creds(bprm);
+
+ commit_creds(bprm->cred);
+ bprm->cred = NULL;
+
+ /*
+ * Disable monitoring for regular users
+ * when executing setuid binaries. Must
+ * wait until new credentials are committed
+ * by commit_creds() above
+ */
+ if (get_dumpable(me->mm) != SUID_DUMP_USER)
+ perf_event_exit_task(me);
+ /*
+ * cred_guard_mutex must be held at least to this point to prevent
+ * ptrace_attach() from altering our determination of the task's
+ * credentials; any time after this it may be unlocked.
+ */
+ security_bprm_committed_creds(bprm);
+
+ /* Pass the opened binary to the interpreter. */
+ if (bprm->have_execfd) {
+ retval = get_unused_fd_flags(0);
+ if (retval < 0)
+ goto out_unlock;
+ fd_install(retval, bprm->executable);
+ bprm->executable = NULL;
+ bprm->execfd = retval;
+ }
return 0;
+out_unlock:
+ mutex_unlock(&me->signal->exec_update_mutex);
out:
return retval;
}
-EXPORT_SYMBOL(flush_old_exec);
+EXPORT_SYMBOL(begin_new_exec);
void would_dump(struct linux_binprm *bprm, struct file *file)
{
@@ -1387,58 +1468,20 @@ EXPORT_SYMBOL(would_dump);
void setup_new_exec(struct linux_binprm * bprm)
{
- /*
- * Once here, prepare_binrpm() will not be called any more, so
- * the final state of setuid/setgid/fscaps can be merged into the
- * secureexec flag.
- */
- bprm->secureexec |= bprm->cap_elevated;
-
- if (bprm->secureexec) {
- /* Make sure parent cannot signal privileged process. */
- current->pdeath_signal = 0;
-
- /*
- * For secureexec, reset the stack limit to sane default to
- * avoid bad behavior from the prior rlimits. This has to
- * happen before arch_pick_mmap_layout(), which examines
- * RLIMIT_STACK, but after the point of no return to avoid
- * needing to clean up the change on failure.
- */
- if (bprm->rlim_stack.rlim_cur > _STK_LIM)
- bprm->rlim_stack.rlim_cur = _STK_LIM;
- }
-
- arch_pick_mmap_layout(current->mm, &bprm->rlim_stack);
-
- current->sas_ss_sp = current->sas_ss_size = 0;
+ /* Setup things that can depend upon the personality */
+ struct task_struct *me = current;
- /*
- * Figure out dumpability. Note that this checking only of current
- * is wrong, but userspace depends on it. This should be testing
- * bprm->secureexec instead.
- */
- if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP ||
- !(uid_eq(current_euid(), current_uid()) &&
- gid_eq(current_egid(), current_gid())))
- set_dumpable(current->mm, suid_dumpable);
- else
- set_dumpable(current->mm, SUID_DUMP_USER);
+ arch_pick_mmap_layout(me->mm, &bprm->rlim_stack);
arch_setup_new_exec();
- perf_event_exec();
- __set_task_comm(current, kbasename(bprm->filename), true);
/* Set the new mm task size. We have to do that late because it may
* depend on TIF_32BIT which is only updated in flush_thread() on
* some architectures like powerpc
*/
- current->mm->task_size = TASK_SIZE;
-
- /* An exec changes our domain. We are no longer part of the thread
- group */
- WRITE_ONCE(current->self_exec_id, current->self_exec_id + 1);
- flush_signal_handlers(current, 0);
+ me->mm->task_size = TASK_SIZE;
+ mutex_unlock(&me->signal->exec_update_mutex);
+ mutex_unlock(&me->signal->cred_guard_mutex);
}
EXPORT_SYMBOL(setup_new_exec);
@@ -1454,7 +1497,7 @@ EXPORT_SYMBOL(finalize_exec);
/*
* Prepare credentials and lock ->cred_guard_mutex.
- * install_exec_creds() commits the new creds and drops the lock.
+ * setup_new_exec() commits the new creds and drops the lock.
* Or, if exec fails before, free_bprm() should release ->cred and
* and unlock.
*/
@@ -1475,8 +1518,6 @@ static void free_bprm(struct linux_binprm *bprm)
{
free_arg_pages(bprm);
if (bprm->cred) {
- if (bprm->called_exec_mmap)
- mutex_unlock(&current->signal->exec_update_mutex);
mutex_unlock(&current->signal->cred_guard_mutex);
abort_creds(bprm->cred);
}
@@ -1484,6 +1525,8 @@ static void free_bprm(struct linux_binprm *bprm)
allow_write_access(bprm->file);
fput(bprm->file);
}
+ if (bprm->executable)
+ fput(bprm->executable);
/* If a binfmt changed the interp, free it. */
if (bprm->interp != bprm->filename)
kfree(bprm->interp);
@@ -1503,35 +1546,6 @@ int bprm_change_interp(const char *interp, struct linux_binprm *bprm)
EXPORT_SYMBOL(bprm_change_interp);
/*
- * install the new credentials for this executable
- */
-void install_exec_creds(struct linux_binprm *bprm)
-{
- security_bprm_committing_creds(bprm);
-
- commit_creds(bprm->cred);
- bprm->cred = NULL;
-
- /*
- * Disable monitoring for regular users
- * when executing setuid binaries. Must
- * wait until new credentials are committed
- * by commit_creds() above
- */
- if (get_dumpable(current->mm) != SUID_DUMP_USER)
- perf_event_exit_task(current);
- /*
- * cred_guard_mutex must be held at least to this point to prevent
- * ptrace_attach() from altering our determination of the task's
- * credentials; any time after this it may be unlocked.
- */
- security_bprm_committed_creds(bprm);
- mutex_unlock(&current->signal->exec_update_mutex);
- mutex_unlock(&current->signal->cred_guard_mutex);
-}
-EXPORT_SYMBOL(install_exec_creds);
-
-/*
* determine how safe it is to execute the proposed program
* - the caller must hold ->cred_guard_mutex to protect against
* PTRACE_ATTACH or seccomp thread-sync
@@ -1568,29 +1582,21 @@ static void check_unsafe_exec(struct linux_binprm *bprm)
spin_unlock(&p->fs->lock);
}
-static void bprm_fill_uid(struct linux_binprm *bprm)
+static void bprm_fill_uid(struct linux_binprm *bprm, struct file *file)
{
+ /* Handle suid and sgid on files */
struct inode *inode;
unsigned int mode;
kuid_t uid;
kgid_t gid;
- /*
- * Since this can be called multiple times (via prepare_binprm),
- * we must clear any previous work done when setting set[ug]id
- * bits from any earlier bprm->file uses (for example when run
- * first for a setuid script then again for its interpreter).
- */
- bprm->cred->euid = current_euid();
- bprm->cred->egid = current_egid();
-
- if (!mnt_may_suid(bprm->file->f_path.mnt))
+ if (!mnt_may_suid(file->f_path.mnt))
return;
if (task_no_new_privs(current))
return;
- inode = bprm->file->f_path.dentry->d_inode;
+ inode = file->f_path.dentry->d_inode;
mode = READ_ONCE(inode->i_mode);
if (!(mode & (S_ISUID|S_ISGID)))
return;
@@ -1621,30 +1627,31 @@ static void bprm_fill_uid(struct linux_binprm *bprm)
}
/*
+ * Compute brpm->cred based upon the final binary.
+ */
+static int bprm_creds_from_file(struct linux_binprm *bprm)
+{
+ /* Compute creds based on which file? */
+ struct file *file = bprm->execfd_creds ? bprm->executable : bprm->file;
+
+ bprm_fill_uid(bprm, file);
+ return security_bprm_creds_from_file(bprm, file);
+}
+
+/*
* Fill the binprm structure from the inode.
- * Check permissions, then read the first BINPRM_BUF_SIZE bytes
+ * Read the first BINPRM_BUF_SIZE bytes
*
* This may be called multiple times for binary chains (scripts for example).
*/
-int prepare_binprm(struct linux_binprm *bprm)
+static int prepare_binprm(struct linux_binprm *bprm)
{
- int retval;
loff_t pos = 0;
- bprm_fill_uid(bprm);
-
- /* fill in binprm security blob */
- retval = security_bprm_set_creds(bprm);
- if (retval)
- return retval;
- bprm->called_set_creds = 1;
-
memset(bprm->buf, 0, BINPRM_BUF_SIZE);
return kernel_read(bprm->file, bprm->buf, BINPRM_BUF_SIZE, &pos);
}
-EXPORT_SYMBOL(prepare_binprm);
-
/*
* Arguments are '\0' separated strings found at the location bprm->p
* points to; chop off the first by relocating brpm->p to right after
@@ -1690,15 +1697,15 @@ EXPORT_SYMBOL(remove_arg_zero);
/*
* cycle the list of binary formats handler, until one recognizes the image
*/
-int search_binary_handler(struct linux_binprm *bprm)
+static int search_binary_handler(struct linux_binprm *bprm)
{
bool need_retry = IS_ENABLED(CONFIG_MODULES);
struct linux_binfmt *fmt;
int retval;
- /* This allows 4 levels of binfmt rewrites before failing hard. */
- if (bprm->recursion_depth > 5)
- return -ELOOP;
+ retval = prepare_binprm(bprm);
+ if (retval < 0)
+ return retval;
retval = security_bprm_check(bprm);
if (retval)
@@ -1712,19 +1719,11 @@ int search_binary_handler(struct linux_binprm *bprm)
continue;
read_unlock(&binfmt_lock);
- bprm->recursion_depth++;
retval = fmt->load_binary(bprm);
- bprm->recursion_depth--;
read_lock(&binfmt_lock);
put_binfmt(fmt);
- if (retval < 0 && bprm->called_exec_mmap) {
- /* we got to flush_old_exec() and failed after it */
- read_unlock(&binfmt_lock);
- force_sigsegv(SIGSEGV);
- return retval;
- }
- if (retval != -ENOEXEC || !bprm->file) {
+ if (bprm->point_of_no_return || (retval != -ENOEXEC)) {
read_unlock(&binfmt_lock);
return retval;
}
@@ -1743,12 +1742,11 @@ int search_binary_handler(struct linux_binprm *bprm)
return retval;
}
-EXPORT_SYMBOL(search_binary_handler);
static int exec_binprm(struct linux_binprm *bprm)
{
pid_t old_pid, old_vpid;
- int ret;
+ int ret, depth;
/* Need to fetch pid before load_binary changes it */
old_pid = current->pid;
@@ -1756,15 +1754,38 @@ static int exec_binprm(struct linux_binprm *bprm)
old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
rcu_read_unlock();
- ret = search_binary_handler(bprm);
- if (ret >= 0) {
- audit_bprm(bprm);
- trace_sched_process_exec(current, old_pid, bprm);
- ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
- proc_exec_connector(current);
+ /* This allows 4 levels of binfmt rewrites before failing hard. */
+ for (depth = 0;; depth++) {
+ struct file *exec;
+ if (depth > 5)
+ return -ELOOP;
+
+ ret = search_binary_handler(bprm);
+ if (ret < 0)
+ return ret;
+ if (!bprm->interpreter)
+ break;
+
+ exec = bprm->file;
+ bprm->file = bprm->interpreter;
+ bprm->interpreter = NULL;
+
+ allow_write_access(exec);
+ if (unlikely(bprm->have_execfd)) {
+ if (bprm->executable) {
+ fput(exec);
+ return -ENOEXEC;
+ }
+ bprm->executable = exec;
+ } else
+ fput(exec);
}
- return ret;
+ audit_bprm(bprm);
+ trace_sched_process_exec(current, old_pid, bprm);
+ ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
+ proc_exec_connector(current);
+ return 0;
}
/*
@@ -1857,8 +1878,9 @@ static int __do_execve_file(int fd, struct filename *filename,
if (retval < 0)
goto out;
- retval = prepare_binprm(bprm);
- if (retval < 0)
+ /* Set the unchanging part of bprm->cred */
+ retval = security_bprm_creds_for_exec(bprm);
+ if (retval)
goto out;
retval = copy_strings_kernel(1, &bprm->filename, bprm);
@@ -1893,6 +1915,14 @@ static int __do_execve_file(int fd, struct filename *filename,
return retval;
out:
+ /*
+ * If past the point of no return ensure the the code never
+ * returns to the userspace process. Use an existing fatal
+ * signal if present otherwise terminate the process with
+ * SIGSEGV.
+ */
+ if (bprm->point_of_no_return && !fatal_signal_pending(current))
+ force_sigsegv(SIGSEGV);
if (bprm->mm) {
acct_arg_size(bprm, 0);
mmput(bprm->mm);
diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h
index a345d9fed3d8..aece1b340e7d 100644
--- a/include/linux/binfmts.h
+++ b/include/linux/binfmts.h
@@ -26,35 +26,27 @@ struct linux_binprm {
unsigned long p; /* current top of mem */
unsigned long argmin; /* rlimit marker for copy_strings() */
unsigned int
+ /* Should an execfd be passed to userspace? */
+ have_execfd:1,
+
+ /* Use the creds of a script (see binfmt_misc) */
+ execfd_creds:1,
/*
- * True after the bprm_set_creds hook has been called once
- * (multiple calls can be made via prepare_binprm() for
- * binfmt_script/misc).
- */
- called_set_creds:1,
- /*
- * True if most recent call to the commoncaps bprm_set_creds
- * hook (due to multiple prepare_binprm() calls from the
- * binfmt_script/misc handlers) resulted in elevated
- * privileges.
- */
- cap_elevated:1,
- /*
- * Set by bprm_set_creds hook to indicate a privilege-gaining
- * exec has happened. Used to sanitize execution environment
- * and to set AT_SECURE auxv for glibc.
+ * Set by bprm_creds_for_exec hook to indicate a
+ * privilege-gaining exec has happened. Used to set
+ * AT_SECURE auxv for glibc.
*/
secureexec:1,
/*
- * Set by flush_old_exec, when exec_mmap has been called.
- * This is past the point of no return, when the
- * exec_update_mutex has been taken.
+ * Set when errors can no longer be returned to the
+ * original userspace.
*/
- called_exec_mmap:1;
+ point_of_no_return:1;
#ifdef __alpha__
unsigned int taso:1;
#endif
- unsigned int recursion_depth; /* only for search_binary_handler() */
+ struct file * executable; /* Executable to pass to the interpreter */
+ struct file * interpreter;
struct file * file;
struct cred *cred; /* new credentials */
int unsafe; /* how unsafe this exec is (mask of LSM_UNSAFE_*) */
@@ -65,7 +57,7 @@ struct linux_binprm {
of the time same as filename, but could be
different for binfmt_{misc,script} */
unsigned interp_flags;
- unsigned interp_data;
+ int execfd; /* File descriptor of the executable */
unsigned long loader, exec;
struct rlimit rlim_stack; /* Saved RLIMIT_STACK used during exec. */
@@ -76,10 +68,6 @@ struct linux_binprm {
#define BINPRM_FLAGS_ENFORCE_NONDUMP_BIT 0
#define BINPRM_FLAGS_ENFORCE_NONDUMP (1 << BINPRM_FLAGS_ENFORCE_NONDUMP_BIT)
-/* fd of the binary should be passed to the interpreter */
-#define BINPRM_FLAGS_EXECFD_BIT 1
-#define BINPRM_FLAGS_EXECFD (1 << BINPRM_FLAGS_EXECFD_BIT)
-
/* filename of the binary will be inaccessible after exec */
#define BINPRM_FLAGS_PATH_INACCESSIBLE_BIT 2
#define BINPRM_FLAGS_PATH_INACCESSIBLE (1 << BINPRM_FLAGS_PATH_INACCESSIBLE_BIT)
@@ -123,10 +111,8 @@ static inline void insert_binfmt(struct linux_binfmt *fmt)
extern void unregister_binfmt(struct linux_binfmt *);
-extern int prepare_binprm(struct linux_binprm *);
extern int __must_check remove_arg_zero(struct linux_binprm *);
-extern int search_binary_handler(struct linux_binprm *);
-extern int flush_old_exec(struct linux_binprm * bprm);
+extern int begin_new_exec(struct linux_binprm * bprm);
extern void setup_new_exec(struct linux_binprm * bprm);
extern void finalize_exec(struct linux_binprm *bprm);
extern void would_dump(struct linux_binprm *, struct file *);
@@ -146,7 +132,6 @@ extern int transfer_args_to_stack(struct linux_binprm *bprm,
extern int bprm_change_interp(const char *interp, struct linux_binprm *bprm);
extern int copy_strings_kernel(int argc, const char *const *argv,
struct linux_binprm *bprm);
-extern void install_exec_creds(struct linux_binprm *bprm);
extern void set_binfmt(struct linux_binfmt *new);
extern ssize_t read_code(struct file *, unsigned long, loff_t, size_t);
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 5616b2567aa7..fb3ce6cec997 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -49,7 +49,8 @@ LSM_HOOK(int, 0, syslog, int type)
LSM_HOOK(int, 0, settime, const struct timespec64 *ts,
const struct timezone *tz)
LSM_HOOK(int, 0, vm_enough_memory, struct mm_struct *mm, long pages)
-LSM_HOOK(int, 0, bprm_set_creds, struct linux_binprm *bprm)
+LSM_HOOK(int, 0, bprm_creds_for_exec, struct linux_binprm *bprm)
+LSM_HOOK(int, 0, bprm_creds_from_file, struct linux_binprm *bprm, struct file *file)
LSM_HOOK(int, 0, bprm_check_security, struct linux_binprm *bprm)
LSM_HOOK(void, LSM_RET_VOID, bprm_committing_creds, struct linux_binprm *bprm)
LSM_HOOK(void, LSM_RET_VOID, bprm_committed_creds, struct linux_binprm *bprm)
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 44d5422c18e4..3e62dab77699 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -34,40 +34,48 @@
*
* Security hooks for program execution operations.
*
- * @bprm_set_creds:
- * Save security information in the bprm->security field, typically based
- * on information about the bprm->file, for later use by the apply_creds
- * hook. This hook may also optionally check permissions (e.g. for
- * transitions between security domains).
- * This hook may be called multiple times during a single execve, e.g. for
- * interpreters. The hook can tell whether it has already been called by
- * checking to see if @bprm->security is non-NULL. If so, then the hook
- * may decide either to retain the security information saved earlier or
- * to replace it. The hook must set @bprm->secureexec to 1 if a "secure
- * exec" has happened as a result of this hook call. The flag is used to
- * indicate the need for a sanitized execution environment, and is also
- * passed in the ELF auxiliary table on the initial stack to indicate
- * whether libc should enable secure mode.
+ * @bprm_creds_for_exec:
+ * If the setup in prepare_exec_creds did not setup @bprm->cred->security
+ * properly for executing @bprm->file, update the LSM's portion of
+ * @bprm->cred->security to be what commit_creds needs to install for the
+ * new program. This hook may also optionally check permissions
+ * (e.g. for transitions between security domains).
+ * The hook must set @bprm->secureexec to 1 if AT_SECURE should be set to
+ * request libc enable secure mode.
+ * @bprm contains the linux_binprm structure.
+ * Return 0 if the hook is successful and permission is granted.
+ * @bprm_creds_from_file:
+ * If @file is setpcap, suid, sgid or otherwise marked to change
+ * privilege upon exec, update @bprm->cred to reflect that change.
+ * This is called after finding the binary that will be executed.
+ * without an interpreter. This ensures that the credentials will not
+ * be derived from a script that the binary will need to reopen, which
+ * when reopend may end up being a completely different file. This
+ * hook may also optionally check permissions (e.g. for transitions
+ * between security domains).
+ * The hook must set @bprm->secureexec to 1 if AT_SECURE should be set to
+ * request libc enable secure mode.
+ * The hook must add to @bprm->per_clear any personality flags that
+ * should be cleared from current->personality.
* @bprm contains the linux_binprm structure.
* Return 0 if the hook is successful and permission is granted.
* @bprm_check_security:
* This hook mediates the point when a search for a binary handler will
- * begin. It allows a check the @bprm->security value which is set in the
- * preceding set_creds call. The primary difference from set_creds is
- * that the argv list and envp list are reliably available in @bprm. This
- * hook may be called multiple times during a single execve; and in each
- * pass set_creds is called first.
+ * begin. It allows a check against the @bprm->cred->security value
+ * which was set in the preceding creds_for_exec call. The argv list and
+ * envp list are reliably available in @bprm. This hook may be called
+ * multiple times during a single execve.
* @bprm contains the linux_binprm structure.
* Return 0 if the hook is successful and permission is granted.
* @bprm_committing_creds:
* Prepare to install the new security attributes of a process being
* transformed by an execve operation, based on the old credentials
* pointed to by @current->cred and the information set in @bprm->cred by
- * the bprm_set_creds hook. @bprm points to the linux_binprm structure.
- * This hook is a good place to perform state changes on the process such
- * as closing open file descriptors to which access will no longer be
- * granted when the attributes are changed. This is called immediately
- * before commit_creds().
+ * the bprm_creds_for_exec hook. @bprm points to the linux_binprm
+ * structure. This hook is a good place to perform state changes on the
+ * process such as closing open file descriptors to which access will no
+ * longer be granted when the attributes are changed. This is called
+ * immediately before commit_creds().
* @bprm_committed_creds:
* Tidy up after the installation of the new security attributes of a
* process being transformed by an execve operation. The new credentials
diff --git a/include/linux/security.h b/include/linux/security.h
index 6aa229b252ce..b3f2cb21b4f2 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -140,7 +140,7 @@ extern int cap_capset(struct cred *new, const struct cred *old,
const kernel_cap_t *effective,
const kernel_cap_t *inheritable,
const kernel_cap_t *permitted);
-extern int cap_bprm_set_creds(struct linux_binprm *bprm);
+extern int cap_bprm_creds_from_file(struct linux_binprm *bprm, struct file *file);
extern int cap_inode_setxattr(struct dentry *dentry, const char *name,
const void *value, size_t size, int flags);
extern int cap_inode_removexattr(struct dentry *dentry, const char *name);
@@ -276,7 +276,8 @@ int security_quota_on(struct dentry *dentry);
int security_syslog(int type);
int security_settime64(const struct timespec64 *ts, const struct timezone *tz);
int security_vm_enough_memory_mm(struct mm_struct *mm, long pages);
-int security_bprm_set_creds(struct linux_binprm *bprm);
+int security_bprm_creds_for_exec(struct linux_binprm *bprm);
+int security_bprm_creds_from_file(struct linux_binprm *bprm, struct file *file);
int security_bprm_check(struct linux_binprm *bprm);
void security_bprm_committing_creds(struct linux_binprm *bprm);
void security_bprm_committed_creds(struct linux_binprm *bprm);
@@ -569,9 +570,15 @@ static inline int security_vm_enough_memory_mm(struct mm_struct *mm, long pages)
return __vm_enough_memory(mm, pages, cap_vm_enough_memory(mm, pages));
}
-static inline int security_bprm_set_creds(struct linux_binprm *bprm)
+static inline int security_bprm_creds_for_exec(struct linux_binprm *bprm)
{
- return cap_bprm_set_creds(bprm);
+ return 0;
+}
+
+static inline int security_bprm_creds_from_file(struct linux_binprm *bprm,
+ struct file *file)
+{
+ return cap_bprm_creds_from_file(bprm, file);
}
static inline int security_bprm_check(struct linux_binprm *bprm)
diff --git a/kernel/cred.c b/kernel/cred.c
index 71a792616917..421b1149c651 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -315,6 +315,9 @@ struct cred *prepare_exec_creds(void)
new->process_keyring = NULL;
#endif
+ new->suid = new->fsuid = new->euid;
+ new->sgid = new->fsgid = new->egid;
+
return new;
}
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 2e330f330303..fcfadecd3a08 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -12220,7 +12220,7 @@ static void perf_event_exit_task_context(struct task_struct *child, int ctxn)
* When a child task exits, feed back event values to parent events.
*
* Can be called with exec_update_mutex held when called from
- * install_exec_creds().
+ * setup_new_exec().
*/
void perf_event_exit_task(struct task_struct *child)
{
diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c
index a84ef030fbd7..745a1cf49003 100644
--- a/security/apparmor/domain.c
+++ b/security/apparmor/domain.c
@@ -854,14 +854,14 @@ static struct aa_label *handle_onexec(struct aa_label *label,
}
/**
- * apparmor_bprm_set_creds - set the new creds on the bprm struct
+ * apparmor_bprm_creds_for_exec - Update the new creds on the bprm struct
* @bprm: binprm for the exec (NOT NULL)
*
* Returns: %0 or error on failure
*
* TODO: once the other paths are done see if we can't refactor into a fn
*/
-int apparmor_bprm_set_creds(struct linux_binprm *bprm)
+int apparmor_bprm_creds_for_exec(struct linux_binprm *bprm)
{
struct aa_task_ctx *ctx;
struct aa_label *label, *new = NULL;
@@ -875,9 +875,6 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
file_inode(bprm->file)->i_mode
};
- if (bprm->called_set_creds)
- return 0;
-
ctx = task_ctx(current);
AA_BUG(!cred_label(bprm->cred));
AA_BUG(!ctx);
diff --git a/security/apparmor/include/domain.h b/security/apparmor/include/domain.h
index 21b875fe2d37..d14928fe1c6f 100644
--- a/security/apparmor/include/domain.h
+++ b/security/apparmor/include/domain.h
@@ -30,7 +30,7 @@ struct aa_domain {
struct aa_label *x_table_lookup(struct aa_profile *profile, u32 xindex,
const char **name);
-int apparmor_bprm_set_creds(struct linux_binprm *bprm);
+int apparmor_bprm_creds_for_exec(struct linux_binprm *bprm);
void aa_free_domain_entries(struct aa_domain *domain);
int aa_change_hat(const char *hats[], int count, u64 token, int flags);
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 27e371b44dad..ef6f7002af28 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -1232,7 +1232,7 @@ static struct security_hook_list apparmor_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(cred_prepare, apparmor_cred_prepare),
LSM_HOOK_INIT(cred_transfer, apparmor_cred_transfer),
- LSM_HOOK_INIT(bprm_set_creds, apparmor_bprm_set_creds),
+ LSM_HOOK_INIT(bprm_creds_for_exec, apparmor_bprm_creds_for_exec),
LSM_HOOK_INIT(bprm_committing_creds, apparmor_bprm_committing_creds),
LSM_HOOK_INIT(bprm_committed_creds, apparmor_bprm_committed_creds),
diff --git a/security/commoncap.c b/security/commoncap.c
index 0ca31c8bc0b1..59bf3c1674c8 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -647,7 +647,8 @@ int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data
* its xattrs and, if present, apply them to the proposed credentials being
* constructed by execve().
*/
-static int get_file_caps(struct linux_binprm *bprm, bool *effective, bool *has_fcap)
+static int get_file_caps(struct linux_binprm *bprm, struct file *file,
+ bool *effective, bool *has_fcap)
{
int rc = 0;
struct cpu_vfs_cap_data vcaps;
@@ -657,7 +658,7 @@ static int get_file_caps(struct linux_binprm *bprm, bool *effective, bool *has_f
if (!file_caps_enabled)
return 0;
- if (!mnt_may_suid(bprm->file->f_path.mnt))
+ if (!mnt_may_suid(file->f_path.mnt))
return 0;
/*
@@ -665,10 +666,10 @@ static int get_file_caps(struct linux_binprm *bprm, bool *effective, bool *has_f
* explicit that capability bits are limited to s_user_ns and its
* descendants.
*/
- if (!current_in_userns(bprm->file->f_path.mnt->mnt_sb->s_user_ns))
+ if (!current_in_userns(file->f_path.mnt->mnt_sb->s_user_ns))
return 0;
- rc = get_vfs_caps_from_disk(bprm->file->f_path.dentry, &vcaps);
+ rc = get_vfs_caps_from_disk(file->f_path.dentry, &vcaps);
if (rc < 0) {
if (rc == -EINVAL)
printk(KERN_NOTICE "Invalid argument reading file caps for %s\n",
@@ -797,26 +798,27 @@ static inline bool nonroot_raised_pE(struct cred *new, const struct cred *old,
}
/**
- * cap_bprm_set_creds - Set up the proposed credentials for execve().
+ * cap_bprm_creds_from_file - Set up the proposed credentials for execve().
* @bprm: The execution parameters, including the proposed creds
+ * @file: The file to pull the credentials from
*
* Set up the proposed credentials for a new execution context being
* constructed by execve(). The proposed creds in @bprm->cred is altered,
* which won't take effect immediately. Returns 0 if successful, -ve on error.
*/
-int cap_bprm_set_creds(struct linux_binprm *bprm)
+int cap_bprm_creds_from_file(struct linux_binprm *bprm, struct file *file)
{
+ /* Process setpcap binaries and capabilities for uid 0 */
const struct cred *old = current_cred();
struct cred *new = bprm->cred;
bool effective = false, has_fcap = false, is_setid;
int ret;
kuid_t root_uid;
- new->cap_ambient = old->cap_ambient;
if (WARN_ON(!cap_ambient_invariant_ok(old)))
return -EPERM;
- ret = get_file_caps(bprm, &effective, &has_fcap);
+ ret = get_file_caps(bprm, file, &effective, &has_fcap);
if (ret < 0)
return ret;
@@ -885,12 +887,11 @@ int cap_bprm_set_creds(struct linux_binprm *bprm)
return -EPERM;
/* Check for privilege-elevated exec. */
- bprm->cap_elevated = 0;
if (is_setid ||
(!__is_real(root_uid, new) &&
(effective ||
__cap_grew(permitted, ambient, new))))
- bprm->cap_elevated = 1;
+ bprm->secureexec = 1;
return 0;
}
@@ -1347,7 +1348,7 @@ static struct security_hook_list capability_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(ptrace_traceme, cap_ptrace_traceme),
LSM_HOOK_INIT(capget, cap_capget),
LSM_HOOK_INIT(capset, cap_capset),
- LSM_HOOK_INIT(bprm_set_creds, cap_bprm_set_creds),
+ LSM_HOOK_INIT(bprm_creds_from_file, cap_bprm_creds_from_file),
LSM_HOOK_INIT(inode_need_killpriv, cap_inode_need_killpriv),
LSM_HOOK_INIT(inode_killpriv, cap_inode_killpriv),
LSM_HOOK_INIT(inode_getsecurity, cap_inode_getsecurity),
diff --git a/security/security.c b/security/security.c
index 51de970fbb1e..11c1a7da4fd1 100644
--- a/security/security.c
+++ b/security/security.c
@@ -823,9 +823,14 @@ int security_vm_enough_memory_mm(struct mm_struct *mm, long pages)
return __vm_enough_memory(mm, pages, cap_sys_admin);
}
-int security_bprm_set_creds(struct linux_binprm *bprm)
+int security_bprm_creds_for_exec(struct linux_binprm *bprm)
{
- return call_int_hook(bprm_set_creds, 0, bprm);
+ return call_int_hook(bprm_creds_for_exec, 0, bprm);
+}
+
+int security_bprm_creds_from_file(struct linux_binprm *bprm, struct file *file)
+{
+ return call_int_hook(bprm_creds_from_file, 0, bprm, file);
}
int security_bprm_check(struct linux_binprm *bprm)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 4c037c2545c1..7e954b555be6 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2286,7 +2286,7 @@ static int check_nnp_nosuid(const struct linux_binprm *bprm,
return -EACCES;
}
-static int selinux_bprm_set_creds(struct linux_binprm *bprm)
+static int selinux_bprm_creds_for_exec(struct linux_binprm *bprm)
{
const struct task_security_struct *old_tsec;
struct task_security_struct *new_tsec;
@@ -2297,8 +2297,6 @@ static int selinux_bprm_set_creds(struct linux_binprm *bprm)
/* SELinux context only depends on initial program or script and not
* the script interpreter */
- if (bprm->called_set_creds)
- return 0;
old_tsec = selinux_cred(current_cred());
new_tsec = selinux_cred(bprm->cred);
@@ -6405,7 +6403,7 @@ static int selinux_setprocattr(const char *name, void *value, size_t size)
/* Permission checking based on the specified context is
performed during the actual operation (execve,
open/mkdir/...), when we know the full context of the
- operation. See selinux_bprm_set_creds for the execve
+ operation. See selinux_bprm_creds_for_exec for the execve
checks and may_create for the file creation checks. The
operation will then fail if the context is not permitted. */
tsec = selinux_cred(new);
@@ -6934,7 +6932,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(netlink_send, selinux_netlink_send),
- LSM_HOOK_INIT(bprm_set_creds, selinux_bprm_set_creds),
+ LSM_HOOK_INIT(bprm_creds_for_exec, selinux_bprm_creds_for_exec),
LSM_HOOK_INIT(bprm_committing_creds, selinux_bprm_committing_creds),
LSM_HOOK_INIT(bprm_committed_creds, selinux_bprm_committed_creds),
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 6d4883a43fff..cd44b79bf1f5 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -887,12 +887,12 @@ static int smack_sb_statfs(struct dentry *dentry)
*/
/**
- * smack_bprm_set_creds - set creds for exec
+ * smack_bprm_creds_for_exec - Update bprm->cred if needed for exec
* @bprm: the exec information
*
* Returns 0 if it gets a blob, -EPERM if exec forbidden and -ENOMEM otherwise
*/
-static int smack_bprm_set_creds(struct linux_binprm *bprm)
+static int smack_bprm_creds_for_exec(struct linux_binprm *bprm)
{
struct inode *inode = file_inode(bprm->file);
struct task_smack *bsp = smack_cred(bprm->cred);
@@ -900,9 +900,6 @@ static int smack_bprm_set_creds(struct linux_binprm *bprm)
struct superblock_smack *sbsp;
int rc;
- if (bprm->called_set_creds)
- return 0;
-
isp = smack_inode(inode);
if (isp->smk_task == NULL || isp->smk_task == bsp->smk_task)
return 0;
@@ -4584,7 +4581,7 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(sb_statfs, smack_sb_statfs),
LSM_HOOK_INIT(sb_set_mnt_opts, smack_set_mnt_opts),
- LSM_HOOK_INIT(bprm_set_creds, smack_bprm_set_creds),
+ LSM_HOOK_INIT(bprm_creds_for_exec, smack_bprm_creds_for_exec),
LSM_HOOK_INIT(inode_alloc_security, smack_inode_alloc_security),
LSM_HOOK_INIT(inode_init_security, smack_inode_init_security),
diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c
index 716c92ec941a..f9adddc42ac8 100644
--- a/security/tomoyo/tomoyo.c
+++ b/security/tomoyo/tomoyo.c
@@ -63,21 +63,15 @@ static void tomoyo_bprm_committed_creds(struct linux_binprm *bprm)
#ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
/**
- * tomoyo_bprm_set_creds - Target for security_bprm_set_creds().
+ * tomoyo_bprm_for_exec - Target for security_bprm_creds_for_exec().
*
* @bprm: Pointer to "struct linux_binprm".
*
* Returns 0.
*/
-static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
+static int tomoyo_bprm_creds_for_exec(struct linux_binprm *bprm)
{
/*
- * Do only if this function is called for the first time of an execve
- * operation.
- */
- if (bprm->called_set_creds)
- return 0;
- /*
* Load policy if /sbin/tomoyo-init exists and /sbin/init is requested
* for the first time.
*/
@@ -539,7 +533,7 @@ static struct security_hook_list tomoyo_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(task_alloc, tomoyo_task_alloc),
LSM_HOOK_INIT(task_free, tomoyo_task_free),
#ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
- LSM_HOOK_INIT(bprm_set_creds, tomoyo_bprm_set_creds),
+ LSM_HOOK_INIT(bprm_creds_for_exec, tomoyo_bprm_creds_for_exec),
#endif
LSM_HOOK_INIT(bprm_check_security, tomoyo_bprm_check_security),
LSM_HOOK_INIT(file_fcntl, tomoyo_file_fcntl),
diff --git a/tools/testing/selftests/exec/Makefile b/tools/testing/selftests/exec/Makefile
index 33339e31e365..7f4527f897c4 100644
--- a/tools/testing/selftests/exec/Makefile
+++ b/tools/testing/selftests/exec/Makefile
@@ -3,6 +3,7 @@ CFLAGS = -Wall
CFLAGS += -Wno-nonnull
CFLAGS += -D_GNU_SOURCE
+TEST_PROGS := binfmt_script
TEST_GEN_PROGS := execveat
TEST_GEN_FILES := execveat.symlink execveat.denatured script subdir
# Makefile is a run-time dependency, since it's accessed by the execveat test
diff --git a/tools/testing/selftests/exec/binfmt_script b/tools/testing/selftests/exec/binfmt_script
new file mode 100755
index 000000000000..05f94a741c7a
--- /dev/null
+++ b/tools/testing/selftests/exec/binfmt_script
@@ -0,0 +1,171 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+#
+# Test that truncation of bprm->buf doesn't cause unexpected execs paths, along
+# with various other pathological cases.
+import os, subprocess
+
+# Relevant commits
+#
+# b5372fe5dc84 ("exec: load_script: Do not exec truncated interpreter path")
+# 6eb3c3d0a52d ("exec: increase BINPRM_BUF_SIZE to 256")
+
+# BINPRM_BUF_SIZE
+SIZE=256
+
+NAME_MAX=int(subprocess.check_output(["getconf", "NAME_MAX", "."]))
+
+test_num=0
+
+code='''#!/usr/bin/perl
+print "Executed interpreter! Args:\n";
+print "0 : '$0'\n";
+$counter = 1;
+foreach my $a (@ARGV) {
+ print "$counter : '$a'\n";
+ $counter++;
+}
+'''
+
+##
+# test - produce a binfmt_script hashbang line for testing
+#
+# @size: bytes for bprm->buf line, including hashbang but not newline
+# @good: whether this script is expected to execute correctly
+# @hashbang: the special 2 bytes for running binfmt_script
+# @leading: any leading whitespace before the executable path
+# @root: start of executable pathname
+# @target: end of executable pathname
+# @arg: bytes following the executable pathname
+# @fill: character to fill between @root and @target to reach @size bytes
+# @newline: character to use as newline, not counted towards @size
+# ...
+def test(name, size, good=True, leading="", root="./", target="/perl",
+ fill="A", arg="", newline="\n", hashbang="#!"):
+ global test_num, tests, NAME_MAX
+ test_num += 1
+ if test_num > tests:
+ raise ValueError("more binfmt_script tests than expected! (want %d, expected %d)"
+ % (test_num, tests))
+
+ middle = ""
+ remaining = size - len(hashbang) - len(leading) - len(root) - len(target) - len(arg)
+ # The middle of the pathname must not exceed NAME_MAX
+ while remaining >= NAME_MAX:
+ middle += fill * (NAME_MAX - 1)
+ middle += '/'
+ remaining -= NAME_MAX
+ middle += fill * remaining
+
+ dirpath = root + middle
+ binary = dirpath + target
+ if len(target):
+ os.makedirs(dirpath, mode=0o755, exist_ok=True)
+ open(binary, "w").write(code)
+ os.chmod(binary, 0o755)
+
+ buf=hashbang + leading + root + middle + target + arg + newline
+ if len(newline) > 0:
+ buf += 'echo this is not really perl\n'
+
+ script = "binfmt_script-%s" % (name)
+ open(script, "w").write(buf)
+ os.chmod(script, 0o755)
+
+ proc = subprocess.Popen(["./%s" % (script)], shell=True,
+ stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
+ stdout = proc.communicate()[0]
+
+ if proc.returncode == 0 and b'Executed interpreter' in stdout:
+ if good:
+ print("ok %d - binfmt_script %s (successful good exec)"
+ % (test_num, name))
+ else:
+ print("not ok %d - binfmt_script %s succeeded when it should have failed"
+ % (test_num, name))
+ else:
+ if good:
+ print("not ok %d - binfmt_script %s failed when it should have succeeded (rc:%d)"
+ % (test_num, name, proc.returncode))
+ else:
+ print("ok %d - binfmt_script %s (correctly failed bad exec)"
+ % (test_num, name))
+
+ # Clean up crazy binaries
+ os.unlink(script)
+ if len(target):
+ elements = binary.split('/')
+ os.unlink(binary)
+ elements.pop()
+ while len(elements) > 1:
+ os.rmdir("/".join(elements))
+ elements.pop()
+
+tests=27
+print("TAP version 1.3")
+print("1..%d" % (tests))
+
+### FAIL (8 tests)
+
+# Entire path is well past the BINFMT_BUF_SIZE.
+test(name="too-big", size=SIZE+80, good=False)
+# Path is right at max size, making it impossible to tell if it was truncated.
+test(name="exact", size=SIZE, good=False)
+# Same as above, but with leading whitespace.
+test(name="exact-space", size=SIZE, good=False, leading=" ")
+# Huge buffer of only whitespace.
+test(name="whitespace-too-big", size=SIZE+71, good=False, root="",
+ fill=" ", target="")
+# A good path, but it gets truncated due to leading whitespace.
+test(name="truncated", size=SIZE+17, good=False, leading=" " * 19)
+# Entirely empty except for #!
+test(name="empty", size=2, good=False, root="",
+ fill="", target="", newline="")
+# Within size, but entirely spaces
+test(name="spaces", size=SIZE-1, good=False, root="", fill=" ",
+ target="", newline="")
+# Newline before binary.
+test(name="newline-prefix", size=SIZE-1, good=False, leading="\n",
+ root="", fill=" ", target="")
+
+### ok (19 tests)
+
+# The original test case that was broken by commit:
+# 8099b047ecc4 ("exec: load_script: don't blindly truncate shebang string")
+test(name="test.pl", size=439, leading=" ",
+ root="./nix/store/bwav8kz8b3y471wjsybgzw84mrh4js9-perl-5.28.1/bin",
+ arg=" -I/nix/store/x6yyav38jgr924nkna62q3pkp0dgmzlx-perl5.28.1-File-Slurp-9999.25/lib/perl5/site_perl -I/nix/store/ha8v67sl8dac92r9z07vzr4gv1y9nwqz-perl5.28.1-Net-DBus-1.1.0/lib/perl5/site_perl -I/nix/store/dcrkvnjmwh69ljsvpbdjjdnqgwx90a9d-perl5.28.1-XML-Parser-2.44/lib/perl5/site_perl -I/nix/store/rmji88k2zz7h4zg97385bygcydrf2q8h-perl5.28.1-XML-Twig-3.52/lib/perl5/site_perl")
+# One byte under size, leaving newline visible.
+test(name="one-under", size=SIZE-1)
+# Two bytes under size, leaving newline visible.
+test(name="two-under", size=SIZE-2)
+# Exact size, but trailing whitespace visible instead of newline
+test(name="exact-trunc-whitespace", size=SIZE, arg=" ")
+# Exact size, but trailing space and first arg char visible instead of newline.
+test(name="exact-trunc-arg", size=SIZE, arg=" f")
+# One bute under, with confirmed non-truncated arg since newline now visible.
+test(name="one-under-full-arg", size=SIZE-1, arg=" f")
+# Short read buffer by one byte.
+test(name="one-under-no-nl", size=SIZE-1, newline="")
+# Short read buffer by half buffer size.
+test(name="half-under-no-nl", size=int(SIZE/2), newline="")
+# One byte under with whitespace arg. leaving wenline visible.
+test(name="one-under-trunc-arg", size=SIZE-1, arg=" ")
+# One byte under with whitespace leading. leaving wenline visible.
+test(name="one-under-leading", size=SIZE-1, leading=" ")
+# One byte under with whitespace leading and as arg. leaving newline visible.
+test(name="one-under-leading-trunc-arg", size=SIZE-1, leading=" ", arg=" ")
+# Same as above, but with 2 bytes under
+test(name="two-under-no-nl", size=SIZE-2, newline="")
+test(name="two-under-trunc-arg", size=SIZE-2, arg=" ")
+test(name="two-under-leading", size=SIZE-2, leading=" ")
+test(name="two-under-leading-trunc-arg", size=SIZE-2, leading=" ", arg=" ")
+# Same as above, but with buffer half filled
+test(name="two-under-no-nl", size=int(SIZE/2), newline="")
+test(name="two-under-trunc-arg", size=int(SIZE/2), arg=" ")
+test(name="two-under-leading", size=int(SIZE/2), leading=" ")
+test(name="two-under-lead-trunc-arg", size=int(SIZE/2), leading=" ", arg=" ")
+
+if test_num != tests:
+ raise ValueError("fewer binfmt_script tests than expected! (ran %d, expected %d"
+ % (test_num, tests))