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| author | Alejandro Colomar <alx.manpages@gmail.com> | 2022-09-09 14:15:08 +0200 |
|---|---|---|
| committer | Alejandro Colomar <alx.manpages@gmail.com> | 2022-09-09 14:15:08 +0200 |
| commit | 96e72ec1fbadd13cbcbc2b263540e4f5e9e09d7c (patch) | |
| tree | 70686b943e33a6e939ad265acb7ddfef70b91f32 /man/man3/fexecve.3 | |
| parent | 8f4ed6463206e8ede815c72085c7305dafc2e4fc (diff) | |
| download | man-pages-96e72ec1fbadd13cbcbc2b263540e4f5e9e09d7c.tar.gz | |
Revert "src.mk, All pages: Move man* to man/"
This reverts commit 70ac1c4785fc1e158ab2349a962dba2526bf4fbc.
Link: <https://lore.kernel.org/linux-man/YxcV4h+Xn7cd6+q2@pevik/T/>
Reported-by: Petr Vorel <pvorel@suse.cz>
Reported-by: Jakub Wilk <jwilk@jwilk.net>
Cc: Stefan Puiu <stefan.puiu@gmail.com>
Signed-off-by: Alex Colomar <alx.manpages@gmail.com>
Diffstat (limited to 'man/man3/fexecve.3')
| -rw-r--r-- | man/man3/fexecve.3 | 178 |
1 files changed, 0 insertions, 178 deletions
diff --git a/man/man3/fexecve.3 b/man/man3/fexecve.3 deleted file mode 100644 index 1498f8cc5b..0000000000 --- a/man/man3/fexecve.3 +++ /dev/null @@ -1,178 +0,0 @@ -.\" Copyright (c) 2006, 2014, Michael Kerrisk -.\" -.\" SPDX-License-Identifier: Linux-man-pages-copyleft -.\" -.TH FEXECVE 3 2021-03-22 "Linux man-pages (unreleased)" -.SH NAME -fexecve \- execute program specified via file descriptor -.SH LIBRARY -Standard C library -.RI ( libc ", " \-lc ) -.SH SYNOPSIS -.nf -.B #include <unistd.h> -.PP -.BI "int fexecve(int " fd ", char *const " argv "[], char *const " envp []); -.fi -.PP -.RS -4 -Feature Test Macro Requirements for glibc (see -.BR feature_test_macros (7)): -.RE -.PP -.BR fexecve (): -.nf - Since glibc 2.10: - _POSIX_C_SOURCE >= 200809L - Before glibc 2.10: - _GNU_SOURCE -.fi -.SH DESCRIPTION -.BR fexecve () -performs the same task as -.BR execve (2), -with the difference that the file to be executed -is specified via a file descriptor, -.IR fd , -rather than via a pathname. -The file descriptor -.I fd -must be opened read-only -.RB ( O_RDONLY ) -or with the -.B O_PATH -flag -and the caller must have permission to execute the file that it refers to. -.SH RETURN VALUE -A successful call to -.BR fexecve () -never returns. -On error, the function does return, with a result value of \-1, and -.I errno -is set to indicate the error. -.SH ERRORS -Errors are as for -.BR execve (2), -with the following additions: -.TP -.B EINVAL -.I fd -is not a valid file descriptor, or -.I argv -is NULL, or -.I envp -is NULL. -.TP -.B ENOENT -The close-on-exec flag is set on -.IR fd , -and -.I fd -refers to a script. -See BUGS. -.TP -.B ENOSYS -The kernel does not provide the -.BR execveat (2) -system call, and the -.I /proc -filesystem could not be accessed. -.SH VERSIONS -.BR fexecve () -is implemented since glibc 2.3.2. -.SH ATTRIBUTES -For an explanation of the terms used in this section, see -.BR attributes (7). -.ad l -.nh -.TS -allbox; -lbx lb lb -l l l. -Interface Attribute Value -T{ -.BR fexecve () -T} Thread safety MT-Safe -.TE -.hy -.ad -.sp 1 -.SH STANDARDS -POSIX.1-2008. -This function is not specified in POSIX.1-2001, -and is not widely available on other systems. -It is specified in POSIX.1-2008. -.SH NOTES -On Linux with glibc versions 2.26 and earlier, -.BR fexecve () -is implemented using the -.BR proc (5) -filesystem, so -.I /proc -needs to be mounted and available at the time of the call. -Since glibc 2.27, -.\" glibc commit 43ffc53a352a67672210c9dd4959f6c6b7407e60 -if the underlying kernel supports the -.BR execveat (2) -system call, then -.BR fexecve () -is implemented using that system call, with the benefit that -.I /proc -does not need to be mounted. -.PP -The idea behind -.BR fexecve () -is to allow the caller to verify (checksum) the contents of -an executable before executing it. -Simply opening the file, checksumming the contents, and then doing an -.BR execve (2) -would not suffice, since, between the two steps, the filename, -or a directory prefix of the pathname, could have been exchanged -(by, for example, modifying the target of a symbolic link). -.BR fexecve () -does not mitigate the problem that the -.I contents -of a file could be changed between the checksumming and the call to -.BR fexecve (); -for that, the solution is to ensure that the permissions on the file -prevent it from being modified by malicious users. -.PP -The natural idiom when using -.BR fexecve () -is to set the close-on-exec flag on -.IR fd , -so that the file descriptor does not leak through to the program -that is executed. -This approach is natural for two reasons. -First, it prevents file descriptors being consumed unnecessarily. -(The executed program normally has no need of a file descriptor -that refers to the program itself.) -Second, if -.BR fexecve () -is used recursively, -employing the close-on-exec flag prevents the file descriptor exhaustion -that would result from the fact that each step in the recursion would -cause one more file descriptor to be passed to the new program. -(But see BUGS.) -.SH BUGS -If -.I fd -refers to a script (i.e., it is an executable text file that names -a script interpreter with a first line that begins with the characters -.IR #! ) -and the close-on-exec flag has been set for -.IR fd , -then -.BR fexecve () -fails with the error -.BR ENOENT . -This error occurs because, -by the time the script interpreter is executed, -.I fd -has already been closed because of the close-on-exec flag. -Thus, the close-on-exec flag can't be set on -.I fd -if it refers to a script, leading to the problems described in NOTES. -.SH SEE ALSO -.BR execve (2), -.BR execveat (2) |