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Diffstat (limited to 'man2/execve.2')
| -rw-r--r-- | man2/execve.2 | 140 |
1 files changed, 67 insertions, 73 deletions
diff --git a/man2/execve.2 b/man2/execve.2 index 819cba3c13..20804ead73 100644 --- a/man2/execve.2 +++ b/man2/execve.2 @@ -552,44 +552,9 @@ See .TP .B ETXTBSY The specified executable was open for writing by one or more processes. -.SH STANDARDS -POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD. +.SH VERSIONS POSIX does not document the #! behavior, but it exists (with some variations) on other UNIX systems. -.\" SVr4 documents additional error -.\" conditions EAGAIN, EINTR, ELIBACC, ENOLINK, EMULTIHOP; POSIX does not -.\" document ETXTBSY, EPERM, EFAULT, ELOOP, EIO, ENFILE, EMFILE, EINVAL, -.\" EISDIR or ELIBBAD error conditions. -.SH NOTES -One sometimes sees -.BR execve () -(and the related functions described in -.BR exec (3)) -described as "executing a -.I new -process" (or similar). -This is a highly misleading description: -there is no new process; -many attributes of the calling process remain unchanged -(in particular, its PID). -All that -.BR execve () -does is arrange for an existing process (the calling process) -to execute a new program. -.PP -Set-user-ID and set-group-ID processes can not be -.BR ptrace (2)d. -.PP -The result of mounting a filesystem -.I nosuid -varies across Linux kernel versions: -some will refuse execution of set-user-ID and set-group-ID -executables when this would -give the user powers they did not have already (and return -.BR EPERM ), -some will just ignore the set-user-ID and set-group-ID bits and -.BR exec () -successfully. .PP On Linux, .I argv @@ -623,23 +588,6 @@ resource limit changes, then the value reported by will also change, to reflect the fact that the limit on space for holding command-line arguments and environment variables has changed. -.PP -In most cases where -.BR execve () -fails, control returns to the original executable image, -and the caller of -.BR execve () -can then handle the error. -However, in (rare) cases (typically caused by resource exhaustion), -failure may occur past the point of no return: -the original executable image has been torn down, -but the new image could not be completely built. -In such cases, the kernel kills the process with a -.\" commit 19d860a140beac48a1377f179e693abe86a9dac9 -.B SIGSEGV -.RB ( SIGKILL -until Linux 3.17) -signal. .\" .SS Interpreter scripts The kernel imposes a maximum length on the text that follows the @@ -671,15 +619,72 @@ are used to delimit the arguments. .PP Linux (like most other modern UNIX systems) ignores the set-user-ID and set-group-ID bits on scripts. -.\" -.\" .SH BUGS -.\" Some Linux versions have failed to check permissions on ELF -.\" interpreters. This is a security hole, because it allows users to -.\" open any file, such as a rewinding tape device, for reading. Some -.\" Linux versions have also had other security holes in -.\" .BR execve () -.\" that could be exploited for denial of service by a suitably crafted -.\" ELF binary. There are no known problems with Linux 2.0.34 or Linux 2.2.15. +.SH STANDARDS +POSIX.1-2008. +.SH HISTORY +POSIX.1-2001, SVr4, 4.3BSD. +.\" SVr4 documents additional error +.\" conditions EAGAIN, EINTR, ELIBACC, ENOLINK, EMULTIHOP; POSIX does not +.\" document ETXTBSY, EPERM, EFAULT, ELOOP, EIO, ENFILE, EMFILE, EINVAL, +.\" EISDIR or ELIBBAD error conditions. +.PP +With UNIX\ V6, the argument list of an +.BR exec () +call was ended by 0, +while the argument list of +.I main +was ended by \-1. +Thus, this argument list was not directly usable in a further +.BR exec () +call. +Since UNIX\ V7, both are NULL. +.SH NOTES +One sometimes sees +.BR execve () +(and the related functions described in +.BR exec (3)) +described as "executing a +.I new +process" (or similar). +This is a highly misleading description: +there is no new process; +many attributes of the calling process remain unchanged +(in particular, its PID). +All that +.BR execve () +does is arrange for an existing process (the calling process) +to execute a new program. +.PP +Set-user-ID and set-group-ID processes can not be +.BR ptrace (2)d. +.PP +The result of mounting a filesystem +.I nosuid +varies across Linux kernel versions: +some will refuse execution of set-user-ID and set-group-ID +executables when this would +give the user powers they did not have already (and return +.BR EPERM ), +some will just ignore the set-user-ID and set-group-ID bits and +.BR exec () +successfully. +.PP +In most cases where +.BR execve () +fails, control returns to the original executable image, +and the caller of +.BR execve () +can then handle the error. +However, in (rare) cases (typically caused by resource exhaustion), +failure may occur past the point of no return: +the original executable image has been torn down, +but the new image could not be completely built. +In such cases, the kernel kills the process with a +.\" commit 19d860a140beac48a1377f179e693abe86a9dac9 +.B SIGSEGV +.RB ( SIGKILL +until Linux 3.17) +signal. .SS execve() and EAGAIN A more detailed explanation of the .B EAGAIN @@ -755,17 +760,6 @@ process flag. The flag is also cleared if a subsequent call to .BR fork (2) by this process succeeds. -.SS Historical -With UNIX\ V6, the argument list of an -.BR exec () -call was ended by 0, -while the argument list of -.I main -was ended by \-1. -Thus, this argument list was not directly usable in a further -.BR exec () -call. -Since UNIX\ V7, both are NULL. .\" .\" .SH BUGS .\" Some Linux versions have failed to check permissions on ELF |