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Support v9.0.2 #192
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92 changes: 92 additions & 0 deletions
92
...ildkit-direct-execve-v9.0/0001-linux-user-have-execve-call-qemu-via-proc-self-exe-t.patch
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Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,92 @@ | ||
From eb0b405afc96509db07402d8dcfdf85228f38740 Mon Sep 17 00:00:00 2001 | ||
From: CrazyMax <crazy-max@users.noreply.github.com> | ||
Date: Fri, 8 Sep 2023 10:47:29 +0200 | ||
Subject: [PATCH 1/7] linux-user: have execve call qemu via /proc/self/exe to | ||
not rely on binfmt_misc | ||
|
||
It is assumed that when a guest program calls execve syscall it wants to | ||
execute a program on the same guest architecture and not the host architecture. | ||
|
||
Previously, such a guest program would have execve syscall error out with: | ||
"exec format error". | ||
|
||
A common solution is to register the qemu binary in binfmt_misc but that is not a | ||
userland-friendly solution, requiring to modify kernel state. | ||
|
||
This patch injects /proc/self/exe as the first parameter and the qemu program name | ||
as argv[0] to execve. | ||
|
||
Signed-off-by: Tibor Vass <tibor@docker.com> | ||
Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com> | ||
--- | ||
linux-user/syscall.c | 44 +++++++++++++++++++++++++++++++------------- | ||
1 file changed, 31 insertions(+), 13 deletions(-) | ||
|
||
diff --git a/linux-user/syscall.c b/linux-user/syscall.c | ||
index 2edbd1ef15..b9808851e0 100644 | ||
--- a/linux-user/syscall.c | ||
+++ b/linux-user/syscall.c | ||
@@ -8489,10 +8489,37 @@ static int do_execv(CPUArchState *cpu_env, int dirfd, | ||
envc++; | ||
} | ||
|
||
- argp = g_new0(char *, argc + 1); | ||
+ argp = g_new0(char *, argc + 4); | ||
envp = g_new0(char *, envc + 1); | ||
|
||
- for (gp = guest_argp, q = argp; gp; gp += sizeof(abi_ulong), q++) { | ||
+ if (!(p = lock_user_string(pathname))) | ||
+ goto execve_efault; | ||
+ | ||
+ /* if pathname is /proc/self/exe then retrieve the path passed to qemu via command line */ | ||
+ if (is_proc_myself(p, "exe")) { | ||
+ CPUState *cpu = env_cpu((CPUArchState *)cpu_env); | ||
+ TaskState *ts = cpu->opaque; | ||
+ p = ts->bprm->filename; | ||
+ } | ||
+ | ||
+ /* retrieve guest argv0 */ | ||
+ if (get_user_ual(addr, guest_argp)) | ||
+ goto execve_efault; | ||
+ | ||
+ /* | ||
+ * From the guest, the call | ||
+ * execve(pathname, [argv0, argv1], envp) | ||
+ * on the host, becomes: | ||
+ * execve("/proc/self/exe", [qemu_progname, "-0", argv0, pathname, argv1], envp) | ||
+ * where qemu_progname is the error message prefix for qemu | ||
+ */ | ||
+ argp[0] = (char*)error_get_progname(); | ||
+ argp[1] = (char*)"-0"; | ||
+ argp[2] = (char*)lock_user_string(addr); | ||
+ argp[3] = p; | ||
+ | ||
+ /* copy guest argv1 onwards to host argv4 onwards */ | ||
+ for (gp = guest_argp + 1*sizeof(abi_ulong), q = argp + 4; gp; gp += sizeof(abi_ulong), q++) { | ||
if (get_user_ual(addr, gp)) { | ||
goto execve_efault; | ||
} | ||
@@ -8531,18 +8558,9 @@ static int do_execv(CPUArchState *cpu_env, int dirfd, | ||
* before the execve completes and makes it the other | ||
* program's problem. | ||
*/ | ||
- p = lock_user_string(pathname); | ||
- if (!p) { | ||
- goto execve_efault; | ||
- } | ||
- | ||
- const char *exe = p; | ||
- if (is_proc_myself(p, "exe")) { | ||
- exe = exec_path; | ||
- } | ||
ret = is_execveat | ||
- ? safe_execveat(dirfd, exe, argp, envp, flags) | ||
- : safe_execve(exe, argp, envp); | ||
+ ? safe_execveat(dirfd, "/proc/self/exe", argp, envp, flags) | ||
+ : safe_execve("/proc/self/exe", argp, envp); | ||
ret = get_errno(ret); | ||
|
||
unlock_user(p, pathname, 0); | ||
-- | ||
2.45.2 | ||
|
76 changes: 76 additions & 0 deletions
76
patches/buildkit-direct-execve-v9.0/0002-linux-user-lookup-user-program-in-PATH.patch
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---|---|---|
@@ -0,0 +1,76 @@ | ||
From edb94403b6a47a010893f31d94c1b722c41597bb Mon Sep 17 00:00:00 2001 | ||
From: Tibor Vass <tibor@docker.com> | ||
Date: Tue, 2 Jun 2020 10:39:48 +0000 | ||
Subject: [PATCH 2/7] linux-user: lookup user program in PATH | ||
|
||
Signed-off-by: Tibor Vass <tibor@docker.com> | ||
--- | ||
linux-user/main.c | 45 ++++++++++++++++++++++++++++++++++++++++++++- | ||
1 file changed, 44 insertions(+), 1 deletion(-) | ||
|
||
diff --git a/linux-user/main.c b/linux-user/main.c | ||
index 149e35432e..dd70ee10f1 100644 | ||
--- a/linux-user/main.c | ||
+++ b/linux-user/main.c | ||
@@ -600,6 +600,45 @@ static void usage(int exitcode) | ||
exit(exitcode); | ||
} | ||
|
||
+/* | ||
+ * path_lookup searches for an executable filename in the directories named by the PATH environment variable. | ||
+ * Returns a copy of filename if it is an absolute path or could not find a match. | ||
+ * Caller is responsible to free returned string. | ||
+ * Adapted from musl's execvp implementation. | ||
+ */ | ||
+static char *path_lookup(char *filename) { | ||
+ const char *p, *z, *path = getenv("PATH"); | ||
+ size_t l, k; | ||
+ struct stat buf; | ||
+ | ||
+ /* if PATH is not set or filename is absolute path return filename */ | ||
+ if (!path || !filename || filename[0] == '/') | ||
+ return strndup(filename, NAME_MAX+1); | ||
+ | ||
+ k = strnlen(filename, NAME_MAX+1); | ||
+ if (k > NAME_MAX) { | ||
+ errno = ENAMETOOLONG; | ||
+ return NULL; | ||
+ } | ||
+ l = strnlen(path, PATH_MAX-1)+1; | ||
+ | ||
+ for (p = path; ; p = z) { | ||
+ char *b = calloc(l+k+1, sizeof(char)); | ||
+ z = strchrnul(p, ':'); | ||
+ if (z-p >= l) { | ||
+ if (!*z++) break; | ||
+ continue; | ||
+ } | ||
+ memcpy(b, p, z-p); | ||
+ b[z-p] = '/'; | ||
+ memcpy(b+(z-p)+(z>p), filename, k+1); | ||
+ if (!stat(b, &buf) && !(buf.st_mode & S_IFDIR) && (buf.st_mode & (S_IXUSR|S_IXGRP|S_IXOTH))) | ||
+ return b; | ||
+ if (!*z++) break; | ||
+ } | ||
+ return strndup(filename, NAME_MAX+1); | ||
+} | ||
+ | ||
static int parse_args(int argc, char **argv) | ||
{ | ||
const char *r; | ||
@@ -665,7 +704,11 @@ static int parse_args(int argc, char **argv) | ||
exit(EXIT_FAILURE); | ||
} | ||
|
||
- exec_path = argv[optind]; | ||
+ /* not freeing exec_path as it is needed for the lifetime of the process */ | ||
+ if (!(exec_path = path_lookup(argv[optind]))) { | ||
+ (void) fprintf(stderr, "qemu: could not find user program %s: %s\n", exec_path, strerror(errno)); | ||
+ exit(EXIT_FAILURE); | ||
+ } | ||
|
||
return optind; | ||
} | ||
-- | ||
2.45.2 | ||
|
104 changes: 104 additions & 0 deletions
104
...ildkit-direct-execve-v9.0/0003-linux-user-path-in-execve-should-be-relative-to-work.patch
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---|---|---|
@@ -0,0 +1,104 @@ | ||
From b455459dc2f3badfc6bc59e334545bcd9ff5d47e Mon Sep 17 00:00:00 2001 | ||
From: CrazyMax <crazy-max@users.noreply.github.com> | ||
Date: Wed, 3 May 2023 20:54:37 +0200 | ||
Subject: [PATCH 3/7] linux-user: path in execve should be relative to working | ||
dir | ||
|
||
Fixes regression introduced in parent commit where PATH handling was introduced. | ||
|
||
When guest calls execve(filename, argp, envp) filename can be relative in which | ||
case Linux makes it relative to the working directory. | ||
|
||
However, since execve is now handled by exec-ing qemu process again, filename | ||
would first get looked up in PATH in main() before calling host's execve. | ||
|
||
With this change, if filename is relative and exists in working directory as | ||
well as in PATH, working directory will get precedence over PATH if guest is | ||
doing an execve syscall, but not if relative filename comes from qemu's argv. | ||
|
||
Signed-off-by: Tibor Vass <tibor@docker.com> | ||
Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com> | ||
--- | ||
include/qemu/path.h | 1 + | ||
linux-user/syscall.c | 9 +++++++-- | ||
util/path.c | 32 ++++++++++++++++++++++++++++++++ | ||
3 files changed, 40 insertions(+), 2 deletions(-) | ||
|
||
diff --git a/include/qemu/path.h b/include/qemu/path.h | ||
index c6292a9709..a81fb51e1f 100644 | ||
--- a/include/qemu/path.h | ||
+++ b/include/qemu/path.h | ||
@@ -3,5 +3,6 @@ | ||
|
||
void init_paths(const char *prefix); | ||
const char *path(const char *pathname); | ||
+const char *prepend_workdir_if_relative(const char *path); | ||
|
||
#endif | ||
diff --git a/linux-user/syscall.c b/linux-user/syscall.c | ||
index b9808851e0..c6de1303ae 100644 | ||
--- a/linux-user/syscall.c | ||
+++ b/linux-user/syscall.c | ||
@@ -8511,12 +8511,17 @@ static int do_execv(CPUArchState *cpu_env, int dirfd, | ||
* execve(pathname, [argv0, argv1], envp) | ||
* on the host, becomes: | ||
* execve("/proc/self/exe", [qemu_progname, "-0", argv0, pathname, argv1], envp) | ||
- * where qemu_progname is the error message prefix for qemu | ||
+ * where qemu_progname is the error message prefix for qemu. | ||
+ * Note: if pathname is relative, it will be prepended with the current working directory. | ||
*/ | ||
argp[0] = (char*)error_get_progname(); | ||
argp[1] = (char*)"-0"; | ||
argp[2] = (char*)lock_user_string(addr); | ||
- argp[3] = p; | ||
+ argp[3] = (char*)prepend_workdir_if_relative(p); | ||
+ if (!argp[3]) { | ||
+ ret = -host_to_target_errno(errno); | ||
+ goto execve_end; | ||
+ } | ||
|
||
/* copy guest argv1 onwards to host argv4 onwards */ | ||
for (gp = guest_argp + 1*sizeof(abi_ulong), q = argp + 4; gp; gp += sizeof(abi_ulong), q++) { | ||
diff --git a/util/path.c b/util/path.c | ||
index 8e174eb436..06fe2663b8 100644 | ||
--- a/util/path.c | ||
+++ b/util/path.c | ||
@@ -68,3 +68,35 @@ const char *path(const char *name) | ||
qemu_mutex_unlock(&lock); | ||
return ret; | ||
} | ||
+ | ||
+/* Prepends working directory if path is relative. | ||
+ * If path is absolute, it is returned as-is without any allocation. | ||
+ * Otherwise, caller is responsible to free returned path. | ||
+ * Returns NULL and sets errno upon error. | ||
+ * Note: realpath is not called to let the kernel do the rest of the resolution. | ||
+ */ | ||
+const char *prepend_workdir_if_relative(const char *path) | ||
+{ | ||
+ char buf[PATH_MAX]; | ||
+ char *p; | ||
+ int i, j, k; | ||
+ | ||
+ if (!path || path[0] == '/') return path; | ||
+ | ||
+ if (!getcwd(buf, PATH_MAX)) return NULL; | ||
+ i = strlen(buf); | ||
+ j = strlen(path); | ||
+ k = i + 1 + j + 1; /* workdir + '/' + path + '\0' */ | ||
+ if (i + j > PATH_MAX) { | ||
+ errno = ERANGE; | ||
+ return NULL; | ||
+ } | ||
+ if (!(p = malloc(k * sizeof(char*)))) return NULL; | ||
+ | ||
+ p[0] = '\0'; | ||
+ | ||
+ if (!strncat(p, buf, i)) return NULL; | ||
+ if (!strncat(p, "/", 1)) return NULL; | ||
+ if (!strncat(p, path, j)) return NULL; | ||
+ return p; | ||
+} | ||
-- | ||
2.45.2 | ||
|
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subreaper-prctl
patch not necessary anymore? relates to #134 (comment)There was a problem hiding this comment.
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Yeah, it should be ok in v9