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Resolve /proc/self/exe when re-exec ourselves

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Use resolved path of /proc/self/exe to workaround Samsung kernel
blocking executables running as UID=0 in paths such as /proc.
This commit is contained in:
topjohnwu 2020-06-25 03:54:53 -07:00
parent c7e6de2748
commit 4e6f42c344
1 changed files with 10 additions and 3 deletions
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13
shell/ash.c
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@ -8252,6 +8252,7 @@ static struct tblentry **cmdtable;
static int builtinloc = -1; /* index in path of %builtin, or -1 */
static char bb_exec_path[4096];
static void
tryexec(IF_FEATURE_SH_STANDALONE(int applet_no,) const char *cmd, char **argv, char **envp)
@ -8266,7 +8267,7 @@ tryexec(IF_FEATURE_SH_STANDALONE(int applet_no,) const char *cmd, char **argv, c
run_noexec_applet_and_exit(applet_no, cmd, argv);
}
/* re-exec ourselves with the new arguments */
execve(bb_busybox_exec_path, argv, envp);
execve(bb_exec_path, argv, envp);
/* If they called chroot or otherwise made the binary no longer
* executable, fall through */
}
@ -8281,7 +8282,7 @@ tryexec(IF_FEATURE_SH_STANDALONE(int applet_no,) const char *cmd, char **argv, c
execve(cmd, argv, envp);
#endif
if (cmd != bb_busybox_exec_path && errno == ENOEXEC) {
if (cmd != bb_exec_path && errno == ENOEXEC) {
/* Run "cmd" as a shell script:
* http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html
* "If the execve() function fails with ENOEXEC, the shell
@ -8299,7 +8300,7 @@ tryexec(IF_FEATURE_SH_STANDALONE(int applet_no,) const char *cmd, char **argv, c
* to interpret foreign ELF binaries as shell scripts.
*/
argv[0] = (char*) cmd;
cmd = bb_busybox_exec_path;
cmd = bb_exec_path;
/* NB: this is only possible because all callers of shellexec()
* ensure that the argv[-1] slot exists!
*/
@ -14699,6 +14700,12 @@ int ash_main(int argc UNUSED_PARAM, char **argv)
init();
setstackmark(&smark);
/*
* Hack: use resolved path of /proc/self/exe to workaround Samsung kernel blocking
* executables running as UID=0 in paths such as /proc
*/
readlink("/proc/self/exe", bb_exec_path, sizeof(bb_exec_path));
#if NUM_SCRIPTS > 0
if (argc < 0)
/* Non-NULL minusc tells procargs that an embedded script is being run */